![Alexei Starovoitov](/assets/img/avatar_default.png)
allow programs read/write skb->mark, tc_index fields and ((struct qdisc_skb_cb *)cb)->data. mark and tc_index are generically useful in TC. cb[0]-cb[4] are primarily used to pass arguments from one program to another called via bpf_tail_call() which can be seen in sockex3_kern.c example. All fields of 'struct __sk_buff' are readable to socket and tc_cls_act progs. mark, tc_index are writeable from tc_cls_act only. cb[0]-cb[4] are writeable by both sockets and tc_cls_act. Add verifier tests and improve sample code. Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2183 lines
60 KiB
C
2183 lines
60 KiB
C
/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*/
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#include <linux/kernel.h>
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#include <linux/types.h>
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#include <linux/slab.h>
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#include <linux/bpf.h>
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#include <linux/filter.h>
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#include <net/netlink.h>
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#include <linux/file.h>
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#include <linux/vmalloc.h>
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/* bpf_check() is a static code analyzer that walks eBPF program
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* instruction by instruction and updates register/stack state.
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* All paths of conditional branches are analyzed until 'bpf_exit' insn.
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*
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* The first pass is depth-first-search to check that the program is a DAG.
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* It rejects the following programs:
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* - larger than BPF_MAXINSNS insns
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* - if loop is present (detected via back-edge)
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* - unreachable insns exist (shouldn't be a forest. program = one function)
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* - out of bounds or malformed jumps
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* The second pass is all possible path descent from the 1st insn.
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* Since it's analyzing all pathes through the program, the length of the
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* analysis is limited to 32k insn, which may be hit even if total number of
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* insn is less then 4K, but there are too many branches that change stack/regs.
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* Number of 'branches to be analyzed' is limited to 1k
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*
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* On entry to each instruction, each register has a type, and the instruction
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* changes the types of the registers depending on instruction semantics.
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* If instruction is BPF_MOV64_REG(BPF_REG_1, BPF_REG_5), then type of R5 is
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* copied to R1.
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*
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* All registers are 64-bit.
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* R0 - return register
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* R1-R5 argument passing registers
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* R6-R9 callee saved registers
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* R10 - frame pointer read-only
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*
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* At the start of BPF program the register R1 contains a pointer to bpf_context
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* and has type PTR_TO_CTX.
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*
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* Verifier tracks arithmetic operations on pointers in case:
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* BPF_MOV64_REG(BPF_REG_1, BPF_REG_10),
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* BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -20),
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* 1st insn copies R10 (which has FRAME_PTR) type into R1
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* and 2nd arithmetic instruction is pattern matched to recognize
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* that it wants to construct a pointer to some element within stack.
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* So after 2nd insn, the register R1 has type PTR_TO_STACK
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* (and -20 constant is saved for further stack bounds checking).
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* Meaning that this reg is a pointer to stack plus known immediate constant.
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*
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* Most of the time the registers have UNKNOWN_VALUE type, which
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* means the register has some value, but it's not a valid pointer.
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* (like pointer plus pointer becomes UNKNOWN_VALUE type)
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*
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* When verifier sees load or store instructions the type of base register
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* can be: PTR_TO_MAP_VALUE, PTR_TO_CTX, FRAME_PTR. These are three pointer
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* types recognized by check_mem_access() function.
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*
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* PTR_TO_MAP_VALUE means that this register is pointing to 'map element value'
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* and the range of [ptr, ptr + map's value_size) is accessible.
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*
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* registers used to pass values to function calls are checked against
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* function argument constraints.
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*
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* ARG_PTR_TO_MAP_KEY is one of such argument constraints.
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* It means that the register type passed to this function must be
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* PTR_TO_STACK and it will be used inside the function as
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* 'pointer to map element key'
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*
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* For example the argument constraints for bpf_map_lookup_elem():
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* .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
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* .arg1_type = ARG_CONST_MAP_PTR,
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* .arg2_type = ARG_PTR_TO_MAP_KEY,
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*
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* ret_type says that this function returns 'pointer to map elem value or null'
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* function expects 1st argument to be a const pointer to 'struct bpf_map' and
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* 2nd argument should be a pointer to stack, which will be used inside
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* the helper function as a pointer to map element key.
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*
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* On the kernel side the helper function looks like:
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* u64 bpf_map_lookup_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
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* {
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* struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
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* void *key = (void *) (unsigned long) r2;
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* void *value;
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*
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* here kernel can access 'key' and 'map' pointers safely, knowing that
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* [key, key + map->key_size) bytes are valid and were initialized on
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* the stack of eBPF program.
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* }
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*
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* Corresponding eBPF program may look like:
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* BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), // after this insn R2 type is FRAME_PTR
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* BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), // after this insn R2 type is PTR_TO_STACK
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* BPF_LD_MAP_FD(BPF_REG_1, map_fd), // after this insn R1 type is CONST_PTR_TO_MAP
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* BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
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* here verifier looks at prototype of map_lookup_elem() and sees:
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* .arg1_type == ARG_CONST_MAP_PTR and R1->type == CONST_PTR_TO_MAP, which is ok,
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* Now verifier knows that this map has key of R1->map_ptr->key_size bytes
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*
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* Then .arg2_type == ARG_PTR_TO_MAP_KEY and R2->type == PTR_TO_STACK, ok so far,
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* Now verifier checks that [R2, R2 + map's key_size) are within stack limits
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* and were initialized prior to this call.
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* If it's ok, then verifier allows this BPF_CALL insn and looks at
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* .ret_type which is RET_PTR_TO_MAP_VALUE_OR_NULL, so it sets
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* R0->type = PTR_TO_MAP_VALUE_OR_NULL which means bpf_map_lookup_elem() function
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* returns ether pointer to map value or NULL.
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*
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* When type PTR_TO_MAP_VALUE_OR_NULL passes through 'if (reg != 0) goto +off'
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* insn, the register holding that pointer in the true branch changes state to
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* PTR_TO_MAP_VALUE and the same register changes state to CONST_IMM in the false
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* branch. See check_cond_jmp_op().
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*
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* After the call R0 is set to return type of the function and registers R1-R5
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* are set to NOT_INIT to indicate that they are no longer readable.
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*/
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/* types of values stored in eBPF registers */
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enum bpf_reg_type {
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NOT_INIT = 0, /* nothing was written into register */
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UNKNOWN_VALUE, /* reg doesn't contain a valid pointer */
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PTR_TO_CTX, /* reg points to bpf_context */
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CONST_PTR_TO_MAP, /* reg points to struct bpf_map */
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PTR_TO_MAP_VALUE, /* reg points to map element value */
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PTR_TO_MAP_VALUE_OR_NULL,/* points to map elem value or NULL */
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FRAME_PTR, /* reg == frame_pointer */
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PTR_TO_STACK, /* reg == frame_pointer + imm */
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CONST_IMM, /* constant integer value */
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};
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struct reg_state {
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enum bpf_reg_type type;
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union {
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/* valid when type == CONST_IMM | PTR_TO_STACK */
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int imm;
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/* valid when type == CONST_PTR_TO_MAP | PTR_TO_MAP_VALUE |
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* PTR_TO_MAP_VALUE_OR_NULL
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*/
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struct bpf_map *map_ptr;
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};
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};
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enum bpf_stack_slot_type {
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STACK_INVALID, /* nothing was stored in this stack slot */
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STACK_SPILL, /* register spilled into stack */
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STACK_MISC /* BPF program wrote some data into this slot */
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};
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#define BPF_REG_SIZE 8 /* size of eBPF register in bytes */
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/* state of the program:
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* type of all registers and stack info
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*/
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struct verifier_state {
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struct reg_state regs[MAX_BPF_REG];
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u8 stack_slot_type[MAX_BPF_STACK];
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struct reg_state spilled_regs[MAX_BPF_STACK / BPF_REG_SIZE];
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};
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/* linked list of verifier states used to prune search */
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struct verifier_state_list {
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struct verifier_state state;
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struct verifier_state_list *next;
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};
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/* verifier_state + insn_idx are pushed to stack when branch is encountered */
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struct verifier_stack_elem {
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/* verifer state is 'st'
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* before processing instruction 'insn_idx'
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* and after processing instruction 'prev_insn_idx'
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*/
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struct verifier_state st;
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int insn_idx;
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int prev_insn_idx;
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struct verifier_stack_elem *next;
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};
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#define MAX_USED_MAPS 64 /* max number of maps accessed by one eBPF program */
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/* single container for all structs
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* one verifier_env per bpf_check() call
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*/
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struct verifier_env {
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struct bpf_prog *prog; /* eBPF program being verified */
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struct verifier_stack_elem *head; /* stack of verifier states to be processed */
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int stack_size; /* number of states to be processed */
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struct verifier_state cur_state; /* current verifier state */
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struct verifier_state_list **explored_states; /* search pruning optimization */
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struct bpf_map *used_maps[MAX_USED_MAPS]; /* array of map's used by eBPF program */
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u32 used_map_cnt; /* number of used maps */
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};
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/* verbose verifier prints what it's seeing
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* bpf_check() is called under lock, so no race to access these global vars
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*/
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static u32 log_level, log_size, log_len;
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static char *log_buf;
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static DEFINE_MUTEX(bpf_verifier_lock);
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/* log_level controls verbosity level of eBPF verifier.
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* verbose() is used to dump the verification trace to the log, so the user
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* can figure out what's wrong with the program
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*/
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static void verbose(const char *fmt, ...)
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{
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va_list args;
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if (log_level == 0 || log_len >= log_size - 1)
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return;
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va_start(args, fmt);
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log_len += vscnprintf(log_buf + log_len, log_size - log_len, fmt, args);
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va_end(args);
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}
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/* string representation of 'enum bpf_reg_type' */
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static const char * const reg_type_str[] = {
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[NOT_INIT] = "?",
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[UNKNOWN_VALUE] = "inv",
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[PTR_TO_CTX] = "ctx",
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[CONST_PTR_TO_MAP] = "map_ptr",
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[PTR_TO_MAP_VALUE] = "map_value",
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[PTR_TO_MAP_VALUE_OR_NULL] = "map_value_or_null",
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[FRAME_PTR] = "fp",
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[PTR_TO_STACK] = "fp",
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[CONST_IMM] = "imm",
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};
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static void print_verifier_state(struct verifier_env *env)
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{
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enum bpf_reg_type t;
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int i;
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for (i = 0; i < MAX_BPF_REG; i++) {
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t = env->cur_state.regs[i].type;
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if (t == NOT_INIT)
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continue;
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verbose(" R%d=%s", i, reg_type_str[t]);
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if (t == CONST_IMM || t == PTR_TO_STACK)
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verbose("%d", env->cur_state.regs[i].imm);
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else if (t == CONST_PTR_TO_MAP || t == PTR_TO_MAP_VALUE ||
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t == PTR_TO_MAP_VALUE_OR_NULL)
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verbose("(ks=%d,vs=%d)",
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env->cur_state.regs[i].map_ptr->key_size,
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env->cur_state.regs[i].map_ptr->value_size);
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}
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for (i = 0; i < MAX_BPF_STACK; i += BPF_REG_SIZE) {
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if (env->cur_state.stack_slot_type[i] == STACK_SPILL)
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verbose(" fp%d=%s", -MAX_BPF_STACK + i,
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reg_type_str[env->cur_state.spilled_regs[i / BPF_REG_SIZE].type]);
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}
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verbose("\n");
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}
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static const char *const bpf_class_string[] = {
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[BPF_LD] = "ld",
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[BPF_LDX] = "ldx",
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[BPF_ST] = "st",
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[BPF_STX] = "stx",
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[BPF_ALU] = "alu",
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[BPF_JMP] = "jmp",
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[BPF_RET] = "BUG",
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[BPF_ALU64] = "alu64",
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};
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static const char *const bpf_alu_string[] = {
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[BPF_ADD >> 4] = "+=",
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[BPF_SUB >> 4] = "-=",
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[BPF_MUL >> 4] = "*=",
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[BPF_DIV >> 4] = "/=",
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[BPF_OR >> 4] = "|=",
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[BPF_AND >> 4] = "&=",
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[BPF_LSH >> 4] = "<<=",
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[BPF_RSH >> 4] = ">>=",
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[BPF_NEG >> 4] = "neg",
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[BPF_MOD >> 4] = "%=",
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[BPF_XOR >> 4] = "^=",
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[BPF_MOV >> 4] = "=",
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[BPF_ARSH >> 4] = "s>>=",
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[BPF_END >> 4] = "endian",
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};
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static const char *const bpf_ldst_string[] = {
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[BPF_W >> 3] = "u32",
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[BPF_H >> 3] = "u16",
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[BPF_B >> 3] = "u8",
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[BPF_DW >> 3] = "u64",
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};
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static const char *const bpf_jmp_string[] = {
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[BPF_JA >> 4] = "jmp",
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[BPF_JEQ >> 4] = "==",
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[BPF_JGT >> 4] = ">",
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[BPF_JGE >> 4] = ">=",
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[BPF_JSET >> 4] = "&",
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[BPF_JNE >> 4] = "!=",
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[BPF_JSGT >> 4] = "s>",
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[BPF_JSGE >> 4] = "s>=",
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[BPF_CALL >> 4] = "call",
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[BPF_EXIT >> 4] = "exit",
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};
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static void print_bpf_insn(struct bpf_insn *insn)
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{
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u8 class = BPF_CLASS(insn->code);
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if (class == BPF_ALU || class == BPF_ALU64) {
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if (BPF_SRC(insn->code) == BPF_X)
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verbose("(%02x) %sr%d %s %sr%d\n",
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insn->code, class == BPF_ALU ? "(u32) " : "",
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insn->dst_reg,
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bpf_alu_string[BPF_OP(insn->code) >> 4],
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class == BPF_ALU ? "(u32) " : "",
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insn->src_reg);
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else
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verbose("(%02x) %sr%d %s %s%d\n",
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insn->code, class == BPF_ALU ? "(u32) " : "",
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insn->dst_reg,
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bpf_alu_string[BPF_OP(insn->code) >> 4],
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class == BPF_ALU ? "(u32) " : "",
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insn->imm);
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} else if (class == BPF_STX) {
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if (BPF_MODE(insn->code) == BPF_MEM)
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verbose("(%02x) *(%s *)(r%d %+d) = r%d\n",
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insn->code,
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bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
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insn->dst_reg,
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insn->off, insn->src_reg);
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else if (BPF_MODE(insn->code) == BPF_XADD)
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verbose("(%02x) lock *(%s *)(r%d %+d) += r%d\n",
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insn->code,
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bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
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insn->dst_reg, insn->off,
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insn->src_reg);
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else
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verbose("BUG_%02x\n", insn->code);
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} else if (class == BPF_ST) {
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if (BPF_MODE(insn->code) != BPF_MEM) {
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verbose("BUG_st_%02x\n", insn->code);
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return;
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}
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verbose("(%02x) *(%s *)(r%d %+d) = %d\n",
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insn->code,
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bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
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insn->dst_reg,
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insn->off, insn->imm);
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} else if (class == BPF_LDX) {
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if (BPF_MODE(insn->code) != BPF_MEM) {
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verbose("BUG_ldx_%02x\n", insn->code);
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return;
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}
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verbose("(%02x) r%d = *(%s *)(r%d %+d)\n",
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insn->code, insn->dst_reg,
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bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
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insn->src_reg, insn->off);
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} else if (class == BPF_LD) {
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if (BPF_MODE(insn->code) == BPF_ABS) {
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verbose("(%02x) r0 = *(%s *)skb[%d]\n",
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insn->code,
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bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
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insn->imm);
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} else if (BPF_MODE(insn->code) == BPF_IND) {
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verbose("(%02x) r0 = *(%s *)skb[r%d + %d]\n",
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insn->code,
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bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
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insn->src_reg, insn->imm);
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} else if (BPF_MODE(insn->code) == BPF_IMM) {
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verbose("(%02x) r%d = 0x%x\n",
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insn->code, insn->dst_reg, insn->imm);
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} else {
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verbose("BUG_ld_%02x\n", insn->code);
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return;
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}
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} else if (class == BPF_JMP) {
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u8 opcode = BPF_OP(insn->code);
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if (opcode == BPF_CALL) {
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verbose("(%02x) call %d\n", insn->code, insn->imm);
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} else if (insn->code == (BPF_JMP | BPF_JA)) {
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verbose("(%02x) goto pc%+d\n",
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insn->code, insn->off);
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} else if (insn->code == (BPF_JMP | BPF_EXIT)) {
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verbose("(%02x) exit\n", insn->code);
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} else if (BPF_SRC(insn->code) == BPF_X) {
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verbose("(%02x) if r%d %s r%d goto pc%+d\n",
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insn->code, insn->dst_reg,
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bpf_jmp_string[BPF_OP(insn->code) >> 4],
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insn->src_reg, insn->off);
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} else {
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verbose("(%02x) if r%d %s 0x%x goto pc%+d\n",
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insn->code, insn->dst_reg,
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bpf_jmp_string[BPF_OP(insn->code) >> 4],
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insn->imm, insn->off);
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}
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|
} else {
|
|
verbose("(%02x) %s\n", insn->code, bpf_class_string[class]);
|
|
}
|
|
}
|
|
|
|
static int pop_stack(struct verifier_env *env, int *prev_insn_idx)
|
|
{
|
|
struct verifier_stack_elem *elem;
|
|
int insn_idx;
|
|
|
|
if (env->head == NULL)
|
|
return -1;
|
|
|
|
memcpy(&env->cur_state, &env->head->st, sizeof(env->cur_state));
|
|
insn_idx = env->head->insn_idx;
|
|
if (prev_insn_idx)
|
|
*prev_insn_idx = env->head->prev_insn_idx;
|
|
elem = env->head->next;
|
|
kfree(env->head);
|
|
env->head = elem;
|
|
env->stack_size--;
|
|
return insn_idx;
|
|
}
|
|
|
|
static struct verifier_state *push_stack(struct verifier_env *env, int insn_idx,
|
|
int prev_insn_idx)
|
|
{
|
|
struct verifier_stack_elem *elem;
|
|
|
|
elem = kmalloc(sizeof(struct verifier_stack_elem), GFP_KERNEL);
|
|
if (!elem)
|
|
goto err;
|
|
|
|
memcpy(&elem->st, &env->cur_state, sizeof(env->cur_state));
|
|
elem->insn_idx = insn_idx;
|
|
elem->prev_insn_idx = prev_insn_idx;
|
|
elem->next = env->head;
|
|
env->head = elem;
|
|
env->stack_size++;
|
|
if (env->stack_size > 1024) {
|
|
verbose("BPF program is too complex\n");
|
|
goto err;
|
|
}
|
|
return &elem->st;
|
|
err:
|
|
/* pop all elements and return */
|
|
while (pop_stack(env, NULL) >= 0);
|
|
return NULL;
|
|
}
|
|
|
|
#define CALLER_SAVED_REGS 6
|
|
static const int caller_saved[CALLER_SAVED_REGS] = {
|
|
BPF_REG_0, BPF_REG_1, BPF_REG_2, BPF_REG_3, BPF_REG_4, BPF_REG_5
|
|
};
|
|
|
|
static void init_reg_state(struct reg_state *regs)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < MAX_BPF_REG; i++) {
|
|
regs[i].type = NOT_INIT;
|
|
regs[i].imm = 0;
|
|
regs[i].map_ptr = NULL;
|
|
}
|
|
|
|
/* frame pointer */
|
|
regs[BPF_REG_FP].type = FRAME_PTR;
|
|
|
|
/* 1st arg to a function */
|
|
regs[BPF_REG_1].type = PTR_TO_CTX;
|
|
}
|
|
|
|
static void mark_reg_unknown_value(struct reg_state *regs, u32 regno)
|
|
{
|
|
BUG_ON(regno >= MAX_BPF_REG);
|
|
regs[regno].type = UNKNOWN_VALUE;
|
|
regs[regno].imm = 0;
|
|
regs[regno].map_ptr = NULL;
|
|
}
|
|
|
|
enum reg_arg_type {
|
|
SRC_OP, /* register is used as source operand */
|
|
DST_OP, /* register is used as destination operand */
|
|
DST_OP_NO_MARK /* same as above, check only, don't mark */
|
|
};
|
|
|
|
static int check_reg_arg(struct reg_state *regs, u32 regno,
|
|
enum reg_arg_type t)
|
|
{
|
|
if (regno >= MAX_BPF_REG) {
|
|
verbose("R%d is invalid\n", regno);
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (t == SRC_OP) {
|
|
/* check whether register used as source operand can be read */
|
|
if (regs[regno].type == NOT_INIT) {
|
|
verbose("R%d !read_ok\n", regno);
|
|
return -EACCES;
|
|
}
|
|
} else {
|
|
/* check whether register used as dest operand can be written to */
|
|
if (regno == BPF_REG_FP) {
|
|
verbose("frame pointer is read only\n");
|
|
return -EACCES;
|
|
}
|
|
if (t == DST_OP)
|
|
mark_reg_unknown_value(regs, regno);
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static int bpf_size_to_bytes(int bpf_size)
|
|
{
|
|
if (bpf_size == BPF_W)
|
|
return 4;
|
|
else if (bpf_size == BPF_H)
|
|
return 2;
|
|
else if (bpf_size == BPF_B)
|
|
return 1;
|
|
else if (bpf_size == BPF_DW)
|
|
return 8;
|
|
else
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* check_stack_read/write functions track spill/fill of registers,
|
|
* stack boundary and alignment are checked in check_mem_access()
|
|
*/
|
|
static int check_stack_write(struct verifier_state *state, int off, int size,
|
|
int value_regno)
|
|
{
|
|
int i;
|
|
/* caller checked that off % size == 0 and -MAX_BPF_STACK <= off < 0,
|
|
* so it's aligned access and [off, off + size) are within stack limits
|
|
*/
|
|
|
|
if (value_regno >= 0 &&
|
|
(state->regs[value_regno].type == PTR_TO_MAP_VALUE ||
|
|
state->regs[value_regno].type == PTR_TO_STACK ||
|
|
state->regs[value_regno].type == PTR_TO_CTX)) {
|
|
|
|
/* register containing pointer is being spilled into stack */
|
|
if (size != BPF_REG_SIZE) {
|
|
verbose("invalid size of register spill\n");
|
|
return -EACCES;
|
|
}
|
|
|
|
/* save register state */
|
|
state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE] =
|
|
state->regs[value_regno];
|
|
|
|
for (i = 0; i < BPF_REG_SIZE; i++)
|
|
state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_SPILL;
|
|
} else {
|
|
/* regular write of data into stack */
|
|
state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE] =
|
|
(struct reg_state) {};
|
|
|
|
for (i = 0; i < size; i++)
|
|
state->stack_slot_type[MAX_BPF_STACK + off + i] = STACK_MISC;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static int check_stack_read(struct verifier_state *state, int off, int size,
|
|
int value_regno)
|
|
{
|
|
u8 *slot_type;
|
|
int i;
|
|
|
|
slot_type = &state->stack_slot_type[MAX_BPF_STACK + off];
|
|
|
|
if (slot_type[0] == STACK_SPILL) {
|
|
if (size != BPF_REG_SIZE) {
|
|
verbose("invalid size of register spill\n");
|
|
return -EACCES;
|
|
}
|
|
for (i = 1; i < BPF_REG_SIZE; i++) {
|
|
if (slot_type[i] != STACK_SPILL) {
|
|
verbose("corrupted spill memory\n");
|
|
return -EACCES;
|
|
}
|
|
}
|
|
|
|
if (value_regno >= 0)
|
|
/* restore register state from stack */
|
|
state->regs[value_regno] =
|
|
state->spilled_regs[(MAX_BPF_STACK + off) / BPF_REG_SIZE];
|
|
return 0;
|
|
} else {
|
|
for (i = 0; i < size; i++) {
|
|
if (slot_type[i] != STACK_MISC) {
|
|
verbose("invalid read from stack off %d+%d size %d\n",
|
|
off, i, size);
|
|
return -EACCES;
|
|
}
|
|
}
|
|
if (value_regno >= 0)
|
|
/* have read misc data from the stack */
|
|
mark_reg_unknown_value(state->regs, value_regno);
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
/* check read/write into map element returned by bpf_map_lookup_elem() */
|
|
static int check_map_access(struct verifier_env *env, u32 regno, int off,
|
|
int size)
|
|
{
|
|
struct bpf_map *map = env->cur_state.regs[regno].map_ptr;
|
|
|
|
if (off < 0 || off + size > map->value_size) {
|
|
verbose("invalid access to map value, value_size=%d off=%d size=%d\n",
|
|
map->value_size, off, size);
|
|
return -EACCES;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/* check access to 'struct bpf_context' fields */
|
|
static int check_ctx_access(struct verifier_env *env, int off, int size,
|
|
enum bpf_access_type t)
|
|
{
|
|
if (env->prog->aux->ops->is_valid_access &&
|
|
env->prog->aux->ops->is_valid_access(off, size, t))
|
|
return 0;
|
|
|
|
verbose("invalid bpf_context access off=%d size=%d\n", off, size);
|
|
return -EACCES;
|
|
}
|
|
|
|
/* check whether memory at (regno + off) is accessible for t = (read | write)
|
|
* if t==write, value_regno is a register which value is stored into memory
|
|
* if t==read, value_regno is a register which will receive the value from memory
|
|
* if t==write && value_regno==-1, some unknown value is stored into memory
|
|
* if t==read && value_regno==-1, don't care what we read from memory
|
|
*/
|
|
static int check_mem_access(struct verifier_env *env, u32 regno, int off,
|
|
int bpf_size, enum bpf_access_type t,
|
|
int value_regno)
|
|
{
|
|
struct verifier_state *state = &env->cur_state;
|
|
int size, err = 0;
|
|
|
|
size = bpf_size_to_bytes(bpf_size);
|
|
if (size < 0)
|
|
return size;
|
|
|
|
if (off % size != 0) {
|
|
verbose("misaligned access off %d size %d\n", off, size);
|
|
return -EACCES;
|
|
}
|
|
|
|
if (state->regs[regno].type == PTR_TO_MAP_VALUE) {
|
|
err = check_map_access(env, regno, off, size);
|
|
if (!err && t == BPF_READ && value_regno >= 0)
|
|
mark_reg_unknown_value(state->regs, value_regno);
|
|
|
|
} else if (state->regs[regno].type == PTR_TO_CTX) {
|
|
err = check_ctx_access(env, off, size, t);
|
|
if (!err && t == BPF_READ && value_regno >= 0)
|
|
mark_reg_unknown_value(state->regs, value_regno);
|
|
|
|
} else if (state->regs[regno].type == FRAME_PTR) {
|
|
if (off >= 0 || off < -MAX_BPF_STACK) {
|
|
verbose("invalid stack off=%d size=%d\n", off, size);
|
|
return -EACCES;
|
|
}
|
|
if (t == BPF_WRITE)
|
|
err = check_stack_write(state, off, size, value_regno);
|
|
else
|
|
err = check_stack_read(state, off, size, value_regno);
|
|
} else {
|
|
verbose("R%d invalid mem access '%s'\n",
|
|
regno, reg_type_str[state->regs[regno].type]);
|
|
return -EACCES;
|
|
}
|
|
return err;
|
|
}
|
|
|
|
static int check_xadd(struct verifier_env *env, struct bpf_insn *insn)
|
|
{
|
|
struct reg_state *regs = env->cur_state.regs;
|
|
int err;
|
|
|
|
if ((BPF_SIZE(insn->code) != BPF_W && BPF_SIZE(insn->code) != BPF_DW) ||
|
|
insn->imm != 0) {
|
|
verbose("BPF_XADD uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* check src1 operand */
|
|
err = check_reg_arg(regs, insn->src_reg, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
|
|
/* check src2 operand */
|
|
err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
|
|
/* check whether atomic_add can read the memory */
|
|
err = check_mem_access(env, insn->dst_reg, insn->off,
|
|
BPF_SIZE(insn->code), BPF_READ, -1);
|
|
if (err)
|
|
return err;
|
|
|
|
/* check whether atomic_add can write into the same memory */
|
|
return check_mem_access(env, insn->dst_reg, insn->off,
|
|
BPF_SIZE(insn->code), BPF_WRITE, -1);
|
|
}
|
|
|
|
/* when register 'regno' is passed into function that will read 'access_size'
|
|
* bytes from that pointer, make sure that it's within stack boundary
|
|
* and all elements of stack are initialized
|
|
*/
|
|
static int check_stack_boundary(struct verifier_env *env,
|
|
int regno, int access_size)
|
|
{
|
|
struct verifier_state *state = &env->cur_state;
|
|
struct reg_state *regs = state->regs;
|
|
int off, i;
|
|
|
|
if (regs[regno].type != PTR_TO_STACK)
|
|
return -EACCES;
|
|
|
|
off = regs[regno].imm;
|
|
if (off >= 0 || off < -MAX_BPF_STACK || off + access_size > 0 ||
|
|
access_size <= 0) {
|
|
verbose("invalid stack type R%d off=%d access_size=%d\n",
|
|
regno, off, access_size);
|
|
return -EACCES;
|
|
}
|
|
|
|
for (i = 0; i < access_size; i++) {
|
|
if (state->stack_slot_type[MAX_BPF_STACK + off + i] != STACK_MISC) {
|
|
verbose("invalid indirect read from stack off %d+%d size %d\n",
|
|
off, i, access_size);
|
|
return -EACCES;
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static int check_func_arg(struct verifier_env *env, u32 regno,
|
|
enum bpf_arg_type arg_type, struct bpf_map **mapp)
|
|
{
|
|
struct reg_state *reg = env->cur_state.regs + regno;
|
|
enum bpf_reg_type expected_type;
|
|
int err = 0;
|
|
|
|
if (arg_type == ARG_DONTCARE)
|
|
return 0;
|
|
|
|
if (reg->type == NOT_INIT) {
|
|
verbose("R%d !read_ok\n", regno);
|
|
return -EACCES;
|
|
}
|
|
|
|
if (arg_type == ARG_ANYTHING)
|
|
return 0;
|
|
|
|
if (arg_type == ARG_PTR_TO_STACK || arg_type == ARG_PTR_TO_MAP_KEY ||
|
|
arg_type == ARG_PTR_TO_MAP_VALUE) {
|
|
expected_type = PTR_TO_STACK;
|
|
} else if (arg_type == ARG_CONST_STACK_SIZE) {
|
|
expected_type = CONST_IMM;
|
|
} else if (arg_type == ARG_CONST_MAP_PTR) {
|
|
expected_type = CONST_PTR_TO_MAP;
|
|
} else if (arg_type == ARG_PTR_TO_CTX) {
|
|
expected_type = PTR_TO_CTX;
|
|
} else {
|
|
verbose("unsupported arg_type %d\n", arg_type);
|
|
return -EFAULT;
|
|
}
|
|
|
|
if (reg->type != expected_type) {
|
|
verbose("R%d type=%s expected=%s\n", regno,
|
|
reg_type_str[reg->type], reg_type_str[expected_type]);
|
|
return -EACCES;
|
|
}
|
|
|
|
if (arg_type == ARG_CONST_MAP_PTR) {
|
|
/* bpf_map_xxx(map_ptr) call: remember that map_ptr */
|
|
*mapp = reg->map_ptr;
|
|
|
|
} else if (arg_type == ARG_PTR_TO_MAP_KEY) {
|
|
/* bpf_map_xxx(..., map_ptr, ..., key) call:
|
|
* check that [key, key + map->key_size) are within
|
|
* stack limits and initialized
|
|
*/
|
|
if (!*mapp) {
|
|
/* in function declaration map_ptr must come before
|
|
* map_key, so that it's verified and known before
|
|
* we have to check map_key here. Otherwise it means
|
|
* that kernel subsystem misconfigured verifier
|
|
*/
|
|
verbose("invalid map_ptr to access map->key\n");
|
|
return -EACCES;
|
|
}
|
|
err = check_stack_boundary(env, regno, (*mapp)->key_size);
|
|
|
|
} else if (arg_type == ARG_PTR_TO_MAP_VALUE) {
|
|
/* bpf_map_xxx(..., map_ptr, ..., value) call:
|
|
* check [value, value + map->value_size) validity
|
|
*/
|
|
if (!*mapp) {
|
|
/* kernel subsystem misconfigured verifier */
|
|
verbose("invalid map_ptr to access map->value\n");
|
|
return -EACCES;
|
|
}
|
|
err = check_stack_boundary(env, regno, (*mapp)->value_size);
|
|
|
|
} else if (arg_type == ARG_CONST_STACK_SIZE) {
|
|
/* bpf_xxx(..., buf, len) call will access 'len' bytes
|
|
* from stack pointer 'buf'. Check it
|
|
* note: regno == len, regno - 1 == buf
|
|
*/
|
|
if (regno == 0) {
|
|
/* kernel subsystem misconfigured verifier */
|
|
verbose("ARG_CONST_STACK_SIZE cannot be first argument\n");
|
|
return -EACCES;
|
|
}
|
|
err = check_stack_boundary(env, regno - 1, reg->imm);
|
|
}
|
|
|
|
return err;
|
|
}
|
|
|
|
static int check_call(struct verifier_env *env, int func_id)
|
|
{
|
|
struct verifier_state *state = &env->cur_state;
|
|
const struct bpf_func_proto *fn = NULL;
|
|
struct reg_state *regs = state->regs;
|
|
struct bpf_map *map = NULL;
|
|
struct reg_state *reg;
|
|
int i, err;
|
|
|
|
/* find function prototype */
|
|
if (func_id < 0 || func_id >= __BPF_FUNC_MAX_ID) {
|
|
verbose("invalid func %d\n", func_id);
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (env->prog->aux->ops->get_func_proto)
|
|
fn = env->prog->aux->ops->get_func_proto(func_id);
|
|
|
|
if (!fn) {
|
|
verbose("unknown func %d\n", func_id);
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* eBPF programs must be GPL compatible to use GPL-ed functions */
|
|
if (!env->prog->gpl_compatible && fn->gpl_only) {
|
|
verbose("cannot call GPL only function from proprietary program\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* check args */
|
|
err = check_func_arg(env, BPF_REG_1, fn->arg1_type, &map);
|
|
if (err)
|
|
return err;
|
|
err = check_func_arg(env, BPF_REG_2, fn->arg2_type, &map);
|
|
if (err)
|
|
return err;
|
|
err = check_func_arg(env, BPF_REG_3, fn->arg3_type, &map);
|
|
if (err)
|
|
return err;
|
|
err = check_func_arg(env, BPF_REG_4, fn->arg4_type, &map);
|
|
if (err)
|
|
return err;
|
|
err = check_func_arg(env, BPF_REG_5, fn->arg5_type, &map);
|
|
if (err)
|
|
return err;
|
|
|
|
/* reset caller saved regs */
|
|
for (i = 0; i < CALLER_SAVED_REGS; i++) {
|
|
reg = regs + caller_saved[i];
|
|
reg->type = NOT_INIT;
|
|
reg->imm = 0;
|
|
}
|
|
|
|
/* update return register */
|
|
if (fn->ret_type == RET_INTEGER) {
|
|
regs[BPF_REG_0].type = UNKNOWN_VALUE;
|
|
} else if (fn->ret_type == RET_VOID) {
|
|
regs[BPF_REG_0].type = NOT_INIT;
|
|
} else if (fn->ret_type == RET_PTR_TO_MAP_VALUE_OR_NULL) {
|
|
regs[BPF_REG_0].type = PTR_TO_MAP_VALUE_OR_NULL;
|
|
/* remember map_ptr, so that check_map_access()
|
|
* can check 'value_size' boundary of memory access
|
|
* to map element returned from bpf_map_lookup_elem()
|
|
*/
|
|
if (map == NULL) {
|
|
verbose("kernel subsystem misconfigured verifier\n");
|
|
return -EINVAL;
|
|
}
|
|
regs[BPF_REG_0].map_ptr = map;
|
|
} else {
|
|
verbose("unknown return type %d of func %d\n",
|
|
fn->ret_type, func_id);
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (map && map->map_type == BPF_MAP_TYPE_PROG_ARRAY &&
|
|
func_id != BPF_FUNC_tail_call)
|
|
/* prog_array map type needs extra care:
|
|
* only allow to pass it into bpf_tail_call() for now.
|
|
* bpf_map_delete_elem() can be allowed in the future,
|
|
* while bpf_map_update_elem() must only be done via syscall
|
|
*/
|
|
return -EINVAL;
|
|
|
|
if (func_id == BPF_FUNC_tail_call &&
|
|
map->map_type != BPF_MAP_TYPE_PROG_ARRAY)
|
|
/* don't allow any other map type to be passed into
|
|
* bpf_tail_call()
|
|
*/
|
|
return -EINVAL;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/* check validity of 32-bit and 64-bit arithmetic operations */
|
|
static int check_alu_op(struct reg_state *regs, struct bpf_insn *insn)
|
|
{
|
|
u8 opcode = BPF_OP(insn->code);
|
|
int err;
|
|
|
|
if (opcode == BPF_END || opcode == BPF_NEG) {
|
|
if (opcode == BPF_NEG) {
|
|
if (BPF_SRC(insn->code) != 0 ||
|
|
insn->src_reg != BPF_REG_0 ||
|
|
insn->off != 0 || insn->imm != 0) {
|
|
verbose("BPF_NEG uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
} else {
|
|
if (insn->src_reg != BPF_REG_0 || insn->off != 0 ||
|
|
(insn->imm != 16 && insn->imm != 32 && insn->imm != 64)) {
|
|
verbose("BPF_END uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
}
|
|
|
|
/* check src operand */
|
|
err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
|
|
/* check dest operand */
|
|
err = check_reg_arg(regs, insn->dst_reg, DST_OP);
|
|
if (err)
|
|
return err;
|
|
|
|
} else if (opcode == BPF_MOV) {
|
|
|
|
if (BPF_SRC(insn->code) == BPF_X) {
|
|
if (insn->imm != 0 || insn->off != 0) {
|
|
verbose("BPF_MOV uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* check src operand */
|
|
err = check_reg_arg(regs, insn->src_reg, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
} else {
|
|
if (insn->src_reg != BPF_REG_0 || insn->off != 0) {
|
|
verbose("BPF_MOV uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
}
|
|
|
|
/* check dest operand */
|
|
err = check_reg_arg(regs, insn->dst_reg, DST_OP);
|
|
if (err)
|
|
return err;
|
|
|
|
if (BPF_SRC(insn->code) == BPF_X) {
|
|
if (BPF_CLASS(insn->code) == BPF_ALU64) {
|
|
/* case: R1 = R2
|
|
* copy register state to dest reg
|
|
*/
|
|
regs[insn->dst_reg] = regs[insn->src_reg];
|
|
} else {
|
|
regs[insn->dst_reg].type = UNKNOWN_VALUE;
|
|
regs[insn->dst_reg].map_ptr = NULL;
|
|
}
|
|
} else {
|
|
/* case: R = imm
|
|
* remember the value we stored into this reg
|
|
*/
|
|
regs[insn->dst_reg].type = CONST_IMM;
|
|
regs[insn->dst_reg].imm = insn->imm;
|
|
}
|
|
|
|
} else if (opcode > BPF_END) {
|
|
verbose("invalid BPF_ALU opcode %x\n", opcode);
|
|
return -EINVAL;
|
|
|
|
} else { /* all other ALU ops: and, sub, xor, add, ... */
|
|
|
|
bool stack_relative = false;
|
|
|
|
if (BPF_SRC(insn->code) == BPF_X) {
|
|
if (insn->imm != 0 || insn->off != 0) {
|
|
verbose("BPF_ALU uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
/* check src1 operand */
|
|
err = check_reg_arg(regs, insn->src_reg, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
} else {
|
|
if (insn->src_reg != BPF_REG_0 || insn->off != 0) {
|
|
verbose("BPF_ALU uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
}
|
|
|
|
/* check src2 operand */
|
|
err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
|
|
if ((opcode == BPF_MOD || opcode == BPF_DIV) &&
|
|
BPF_SRC(insn->code) == BPF_K && insn->imm == 0) {
|
|
verbose("div by zero\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* pattern match 'bpf_add Rx, imm' instruction */
|
|
if (opcode == BPF_ADD && BPF_CLASS(insn->code) == BPF_ALU64 &&
|
|
regs[insn->dst_reg].type == FRAME_PTR &&
|
|
BPF_SRC(insn->code) == BPF_K)
|
|
stack_relative = true;
|
|
|
|
/* check dest operand */
|
|
err = check_reg_arg(regs, insn->dst_reg, DST_OP);
|
|
if (err)
|
|
return err;
|
|
|
|
if (stack_relative) {
|
|
regs[insn->dst_reg].type = PTR_TO_STACK;
|
|
regs[insn->dst_reg].imm = insn->imm;
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int check_cond_jmp_op(struct verifier_env *env,
|
|
struct bpf_insn *insn, int *insn_idx)
|
|
{
|
|
struct reg_state *regs = env->cur_state.regs;
|
|
struct verifier_state *other_branch;
|
|
u8 opcode = BPF_OP(insn->code);
|
|
int err;
|
|
|
|
if (opcode > BPF_EXIT) {
|
|
verbose("invalid BPF_JMP opcode %x\n", opcode);
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (BPF_SRC(insn->code) == BPF_X) {
|
|
if (insn->imm != 0) {
|
|
verbose("BPF_JMP uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* check src1 operand */
|
|
err = check_reg_arg(regs, insn->src_reg, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
} else {
|
|
if (insn->src_reg != BPF_REG_0) {
|
|
verbose("BPF_JMP uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
}
|
|
|
|
/* check src2 operand */
|
|
err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
|
|
/* detect if R == 0 where R was initialized to zero earlier */
|
|
if (BPF_SRC(insn->code) == BPF_K &&
|
|
(opcode == BPF_JEQ || opcode == BPF_JNE) &&
|
|
regs[insn->dst_reg].type == CONST_IMM &&
|
|
regs[insn->dst_reg].imm == insn->imm) {
|
|
if (opcode == BPF_JEQ) {
|
|
/* if (imm == imm) goto pc+off;
|
|
* only follow the goto, ignore fall-through
|
|
*/
|
|
*insn_idx += insn->off;
|
|
return 0;
|
|
} else {
|
|
/* if (imm != imm) goto pc+off;
|
|
* only follow fall-through branch, since
|
|
* that's where the program will go
|
|
*/
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
other_branch = push_stack(env, *insn_idx + insn->off + 1, *insn_idx);
|
|
if (!other_branch)
|
|
return -EFAULT;
|
|
|
|
/* detect if R == 0 where R is returned value from bpf_map_lookup_elem() */
|
|
if (BPF_SRC(insn->code) == BPF_K &&
|
|
insn->imm == 0 && (opcode == BPF_JEQ ||
|
|
opcode == BPF_JNE) &&
|
|
regs[insn->dst_reg].type == PTR_TO_MAP_VALUE_OR_NULL) {
|
|
if (opcode == BPF_JEQ) {
|
|
/* next fallthrough insn can access memory via
|
|
* this register
|
|
*/
|
|
regs[insn->dst_reg].type = PTR_TO_MAP_VALUE;
|
|
/* branch targer cannot access it, since reg == 0 */
|
|
other_branch->regs[insn->dst_reg].type = CONST_IMM;
|
|
other_branch->regs[insn->dst_reg].imm = 0;
|
|
} else {
|
|
other_branch->regs[insn->dst_reg].type = PTR_TO_MAP_VALUE;
|
|
regs[insn->dst_reg].type = CONST_IMM;
|
|
regs[insn->dst_reg].imm = 0;
|
|
}
|
|
} else if (BPF_SRC(insn->code) == BPF_K &&
|
|
(opcode == BPF_JEQ || opcode == BPF_JNE)) {
|
|
|
|
if (opcode == BPF_JEQ) {
|
|
/* detect if (R == imm) goto
|
|
* and in the target state recognize that R = imm
|
|
*/
|
|
other_branch->regs[insn->dst_reg].type = CONST_IMM;
|
|
other_branch->regs[insn->dst_reg].imm = insn->imm;
|
|
} else {
|
|
/* detect if (R != imm) goto
|
|
* and in the fall-through state recognize that R = imm
|
|
*/
|
|
regs[insn->dst_reg].type = CONST_IMM;
|
|
regs[insn->dst_reg].imm = insn->imm;
|
|
}
|
|
}
|
|
if (log_level)
|
|
print_verifier_state(env);
|
|
return 0;
|
|
}
|
|
|
|
/* return the map pointer stored inside BPF_LD_IMM64 instruction */
|
|
static struct bpf_map *ld_imm64_to_map_ptr(struct bpf_insn *insn)
|
|
{
|
|
u64 imm64 = ((u64) (u32) insn[0].imm) | ((u64) (u32) insn[1].imm) << 32;
|
|
|
|
return (struct bpf_map *) (unsigned long) imm64;
|
|
}
|
|
|
|
/* verify BPF_LD_IMM64 instruction */
|
|
static int check_ld_imm(struct verifier_env *env, struct bpf_insn *insn)
|
|
{
|
|
struct reg_state *regs = env->cur_state.regs;
|
|
int err;
|
|
|
|
if (BPF_SIZE(insn->code) != BPF_DW) {
|
|
verbose("invalid BPF_LD_IMM insn\n");
|
|
return -EINVAL;
|
|
}
|
|
if (insn->off != 0) {
|
|
verbose("BPF_LD_IMM64 uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
err = check_reg_arg(regs, insn->dst_reg, DST_OP);
|
|
if (err)
|
|
return err;
|
|
|
|
if (insn->src_reg == 0)
|
|
/* generic move 64-bit immediate into a register */
|
|
return 0;
|
|
|
|
/* replace_map_fd_with_map_ptr() should have caught bad ld_imm64 */
|
|
BUG_ON(insn->src_reg != BPF_PSEUDO_MAP_FD);
|
|
|
|
regs[insn->dst_reg].type = CONST_PTR_TO_MAP;
|
|
regs[insn->dst_reg].map_ptr = ld_imm64_to_map_ptr(insn);
|
|
return 0;
|
|
}
|
|
|
|
static bool may_access_skb(enum bpf_prog_type type)
|
|
{
|
|
switch (type) {
|
|
case BPF_PROG_TYPE_SOCKET_FILTER:
|
|
case BPF_PROG_TYPE_SCHED_CLS:
|
|
case BPF_PROG_TYPE_SCHED_ACT:
|
|
return true;
|
|
default:
|
|
return false;
|
|
}
|
|
}
|
|
|
|
/* verify safety of LD_ABS|LD_IND instructions:
|
|
* - they can only appear in the programs where ctx == skb
|
|
* - since they are wrappers of function calls, they scratch R1-R5 registers,
|
|
* preserve R6-R9, and store return value into R0
|
|
*
|
|
* Implicit input:
|
|
* ctx == skb == R6 == CTX
|
|
*
|
|
* Explicit input:
|
|
* SRC == any register
|
|
* IMM == 32-bit immediate
|
|
*
|
|
* Output:
|
|
* R0 - 8/16/32-bit skb data converted to cpu endianness
|
|
*/
|
|
static int check_ld_abs(struct verifier_env *env, struct bpf_insn *insn)
|
|
{
|
|
struct reg_state *regs = env->cur_state.regs;
|
|
u8 mode = BPF_MODE(insn->code);
|
|
struct reg_state *reg;
|
|
int i, err;
|
|
|
|
if (!may_access_skb(env->prog->type)) {
|
|
verbose("BPF_LD_ABS|IND instructions not allowed for this program type\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (insn->dst_reg != BPF_REG_0 || insn->off != 0 ||
|
|
(mode == BPF_ABS && insn->src_reg != BPF_REG_0)) {
|
|
verbose("BPF_LD_ABS uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* check whether implicit source operand (register R6) is readable */
|
|
err = check_reg_arg(regs, BPF_REG_6, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
|
|
if (regs[BPF_REG_6].type != PTR_TO_CTX) {
|
|
verbose("at the time of BPF_LD_ABS|IND R6 != pointer to skb\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (mode == BPF_IND) {
|
|
/* check explicit source operand */
|
|
err = check_reg_arg(regs, insn->src_reg, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
}
|
|
|
|
/* reset caller saved regs to unreadable */
|
|
for (i = 0; i < CALLER_SAVED_REGS; i++) {
|
|
reg = regs + caller_saved[i];
|
|
reg->type = NOT_INIT;
|
|
reg->imm = 0;
|
|
}
|
|
|
|
/* mark destination R0 register as readable, since it contains
|
|
* the value fetched from the packet
|
|
*/
|
|
regs[BPF_REG_0].type = UNKNOWN_VALUE;
|
|
return 0;
|
|
}
|
|
|
|
/* non-recursive DFS pseudo code
|
|
* 1 procedure DFS-iterative(G,v):
|
|
* 2 label v as discovered
|
|
* 3 let S be a stack
|
|
* 4 S.push(v)
|
|
* 5 while S is not empty
|
|
* 6 t <- S.pop()
|
|
* 7 if t is what we're looking for:
|
|
* 8 return t
|
|
* 9 for all edges e in G.adjacentEdges(t) do
|
|
* 10 if edge e is already labelled
|
|
* 11 continue with the next edge
|
|
* 12 w <- G.adjacentVertex(t,e)
|
|
* 13 if vertex w is not discovered and not explored
|
|
* 14 label e as tree-edge
|
|
* 15 label w as discovered
|
|
* 16 S.push(w)
|
|
* 17 continue at 5
|
|
* 18 else if vertex w is discovered
|
|
* 19 label e as back-edge
|
|
* 20 else
|
|
* 21 // vertex w is explored
|
|
* 22 label e as forward- or cross-edge
|
|
* 23 label t as explored
|
|
* 24 S.pop()
|
|
*
|
|
* convention:
|
|
* 0x10 - discovered
|
|
* 0x11 - discovered and fall-through edge labelled
|
|
* 0x12 - discovered and fall-through and branch edges labelled
|
|
* 0x20 - explored
|
|
*/
|
|
|
|
enum {
|
|
DISCOVERED = 0x10,
|
|
EXPLORED = 0x20,
|
|
FALLTHROUGH = 1,
|
|
BRANCH = 2,
|
|
};
|
|
|
|
#define STATE_LIST_MARK ((struct verifier_state_list *) -1L)
|
|
|
|
static int *insn_stack; /* stack of insns to process */
|
|
static int cur_stack; /* current stack index */
|
|
static int *insn_state;
|
|
|
|
/* t, w, e - match pseudo-code above:
|
|
* t - index of current instruction
|
|
* w - next instruction
|
|
* e - edge
|
|
*/
|
|
static int push_insn(int t, int w, int e, struct verifier_env *env)
|
|
{
|
|
if (e == FALLTHROUGH && insn_state[t] >= (DISCOVERED | FALLTHROUGH))
|
|
return 0;
|
|
|
|
if (e == BRANCH && insn_state[t] >= (DISCOVERED | BRANCH))
|
|
return 0;
|
|
|
|
if (w < 0 || w >= env->prog->len) {
|
|
verbose("jump out of range from insn %d to %d\n", t, w);
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (e == BRANCH)
|
|
/* mark branch target for state pruning */
|
|
env->explored_states[w] = STATE_LIST_MARK;
|
|
|
|
if (insn_state[w] == 0) {
|
|
/* tree-edge */
|
|
insn_state[t] = DISCOVERED | e;
|
|
insn_state[w] = DISCOVERED;
|
|
if (cur_stack >= env->prog->len)
|
|
return -E2BIG;
|
|
insn_stack[cur_stack++] = w;
|
|
return 1;
|
|
} else if ((insn_state[w] & 0xF0) == DISCOVERED) {
|
|
verbose("back-edge from insn %d to %d\n", t, w);
|
|
return -EINVAL;
|
|
} else if (insn_state[w] == EXPLORED) {
|
|
/* forward- or cross-edge */
|
|
insn_state[t] = DISCOVERED | e;
|
|
} else {
|
|
verbose("insn state internal bug\n");
|
|
return -EFAULT;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/* non-recursive depth-first-search to detect loops in BPF program
|
|
* loop == back-edge in directed graph
|
|
*/
|
|
static int check_cfg(struct verifier_env *env)
|
|
{
|
|
struct bpf_insn *insns = env->prog->insnsi;
|
|
int insn_cnt = env->prog->len;
|
|
int ret = 0;
|
|
int i, t;
|
|
|
|
insn_state = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL);
|
|
if (!insn_state)
|
|
return -ENOMEM;
|
|
|
|
insn_stack = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL);
|
|
if (!insn_stack) {
|
|
kfree(insn_state);
|
|
return -ENOMEM;
|
|
}
|
|
|
|
insn_state[0] = DISCOVERED; /* mark 1st insn as discovered */
|
|
insn_stack[0] = 0; /* 0 is the first instruction */
|
|
cur_stack = 1;
|
|
|
|
peek_stack:
|
|
if (cur_stack == 0)
|
|
goto check_state;
|
|
t = insn_stack[cur_stack - 1];
|
|
|
|
if (BPF_CLASS(insns[t].code) == BPF_JMP) {
|
|
u8 opcode = BPF_OP(insns[t].code);
|
|
|
|
if (opcode == BPF_EXIT) {
|
|
goto mark_explored;
|
|
} else if (opcode == BPF_CALL) {
|
|
ret = push_insn(t, t + 1, FALLTHROUGH, env);
|
|
if (ret == 1)
|
|
goto peek_stack;
|
|
else if (ret < 0)
|
|
goto err_free;
|
|
} else if (opcode == BPF_JA) {
|
|
if (BPF_SRC(insns[t].code) != BPF_K) {
|
|
ret = -EINVAL;
|
|
goto err_free;
|
|
}
|
|
/* unconditional jump with single edge */
|
|
ret = push_insn(t, t + insns[t].off + 1,
|
|
FALLTHROUGH, env);
|
|
if (ret == 1)
|
|
goto peek_stack;
|
|
else if (ret < 0)
|
|
goto err_free;
|
|
/* tell verifier to check for equivalent states
|
|
* after every call and jump
|
|
*/
|
|
if (t + 1 < insn_cnt)
|
|
env->explored_states[t + 1] = STATE_LIST_MARK;
|
|
} else {
|
|
/* conditional jump with two edges */
|
|
ret = push_insn(t, t + 1, FALLTHROUGH, env);
|
|
if (ret == 1)
|
|
goto peek_stack;
|
|
else if (ret < 0)
|
|
goto err_free;
|
|
|
|
ret = push_insn(t, t + insns[t].off + 1, BRANCH, env);
|
|
if (ret == 1)
|
|
goto peek_stack;
|
|
else if (ret < 0)
|
|
goto err_free;
|
|
}
|
|
} else {
|
|
/* all other non-branch instructions with single
|
|
* fall-through edge
|
|
*/
|
|
ret = push_insn(t, t + 1, FALLTHROUGH, env);
|
|
if (ret == 1)
|
|
goto peek_stack;
|
|
else if (ret < 0)
|
|
goto err_free;
|
|
}
|
|
|
|
mark_explored:
|
|
insn_state[t] = EXPLORED;
|
|
if (cur_stack-- <= 0) {
|
|
verbose("pop stack internal bug\n");
|
|
ret = -EFAULT;
|
|
goto err_free;
|
|
}
|
|
goto peek_stack;
|
|
|
|
check_state:
|
|
for (i = 0; i < insn_cnt; i++) {
|
|
if (insn_state[i] != EXPLORED) {
|
|
verbose("unreachable insn %d\n", i);
|
|
ret = -EINVAL;
|
|
goto err_free;
|
|
}
|
|
}
|
|
ret = 0; /* cfg looks good */
|
|
|
|
err_free:
|
|
kfree(insn_state);
|
|
kfree(insn_stack);
|
|
return ret;
|
|
}
|
|
|
|
/* compare two verifier states
|
|
*
|
|
* all states stored in state_list are known to be valid, since
|
|
* verifier reached 'bpf_exit' instruction through them
|
|
*
|
|
* this function is called when verifier exploring different branches of
|
|
* execution popped from the state stack. If it sees an old state that has
|
|
* more strict register state and more strict stack state then this execution
|
|
* branch doesn't need to be explored further, since verifier already
|
|
* concluded that more strict state leads to valid finish.
|
|
*
|
|
* Therefore two states are equivalent if register state is more conservative
|
|
* and explored stack state is more conservative than the current one.
|
|
* Example:
|
|
* explored current
|
|
* (slot1=INV slot2=MISC) == (slot1=MISC slot2=MISC)
|
|
* (slot1=MISC slot2=MISC) != (slot1=INV slot2=MISC)
|
|
*
|
|
* In other words if current stack state (one being explored) has more
|
|
* valid slots than old one that already passed validation, it means
|
|
* the verifier can stop exploring and conclude that current state is valid too
|
|
*
|
|
* Similarly with registers. If explored state has register type as invalid
|
|
* whereas register type in current state is meaningful, it means that
|
|
* the current state will reach 'bpf_exit' instruction safely
|
|
*/
|
|
static bool states_equal(struct verifier_state *old, struct verifier_state *cur)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < MAX_BPF_REG; i++) {
|
|
if (memcmp(&old->regs[i], &cur->regs[i],
|
|
sizeof(old->regs[0])) != 0) {
|
|
if (old->regs[i].type == NOT_INIT ||
|
|
(old->regs[i].type == UNKNOWN_VALUE &&
|
|
cur->regs[i].type != NOT_INIT))
|
|
continue;
|
|
return false;
|
|
}
|
|
}
|
|
|
|
for (i = 0; i < MAX_BPF_STACK; i++) {
|
|
if (old->stack_slot_type[i] == STACK_INVALID)
|
|
continue;
|
|
if (old->stack_slot_type[i] != cur->stack_slot_type[i])
|
|
/* Ex: old explored (safe) state has STACK_SPILL in
|
|
* this stack slot, but current has has STACK_MISC ->
|
|
* this verifier states are not equivalent,
|
|
* return false to continue verification of this path
|
|
*/
|
|
return false;
|
|
if (i % BPF_REG_SIZE)
|
|
continue;
|
|
if (memcmp(&old->spilled_regs[i / BPF_REG_SIZE],
|
|
&cur->spilled_regs[i / BPF_REG_SIZE],
|
|
sizeof(old->spilled_regs[0])))
|
|
/* when explored and current stack slot types are
|
|
* the same, check that stored pointers types
|
|
* are the same as well.
|
|
* Ex: explored safe path could have stored
|
|
* (struct reg_state) {.type = PTR_TO_STACK, .imm = -8}
|
|
* but current path has stored:
|
|
* (struct reg_state) {.type = PTR_TO_STACK, .imm = -16}
|
|
* such verifier states are not equivalent.
|
|
* return false to continue verification of this path
|
|
*/
|
|
return false;
|
|
else
|
|
continue;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
static int is_state_visited(struct verifier_env *env, int insn_idx)
|
|
{
|
|
struct verifier_state_list *new_sl;
|
|
struct verifier_state_list *sl;
|
|
|
|
sl = env->explored_states[insn_idx];
|
|
if (!sl)
|
|
/* this 'insn_idx' instruction wasn't marked, so we will not
|
|
* be doing state search here
|
|
*/
|
|
return 0;
|
|
|
|
while (sl != STATE_LIST_MARK) {
|
|
if (states_equal(&sl->state, &env->cur_state))
|
|
/* reached equivalent register/stack state,
|
|
* prune the search
|
|
*/
|
|
return 1;
|
|
sl = sl->next;
|
|
}
|
|
|
|
/* there were no equivalent states, remember current one.
|
|
* technically the current state is not proven to be safe yet,
|
|
* but it will either reach bpf_exit (which means it's safe) or
|
|
* it will be rejected. Since there are no loops, we won't be
|
|
* seeing this 'insn_idx' instruction again on the way to bpf_exit
|
|
*/
|
|
new_sl = kmalloc(sizeof(struct verifier_state_list), GFP_USER);
|
|
if (!new_sl)
|
|
return -ENOMEM;
|
|
|
|
/* add new state to the head of linked list */
|
|
memcpy(&new_sl->state, &env->cur_state, sizeof(env->cur_state));
|
|
new_sl->next = env->explored_states[insn_idx];
|
|
env->explored_states[insn_idx] = new_sl;
|
|
return 0;
|
|
}
|
|
|
|
static int do_check(struct verifier_env *env)
|
|
{
|
|
struct verifier_state *state = &env->cur_state;
|
|
struct bpf_insn *insns = env->prog->insnsi;
|
|
struct reg_state *regs = state->regs;
|
|
int insn_cnt = env->prog->len;
|
|
int insn_idx, prev_insn_idx = 0;
|
|
int insn_processed = 0;
|
|
bool do_print_state = false;
|
|
|
|
init_reg_state(regs);
|
|
insn_idx = 0;
|
|
for (;;) {
|
|
struct bpf_insn *insn;
|
|
u8 class;
|
|
int err;
|
|
|
|
if (insn_idx >= insn_cnt) {
|
|
verbose("invalid insn idx %d insn_cnt %d\n",
|
|
insn_idx, insn_cnt);
|
|
return -EFAULT;
|
|
}
|
|
|
|
insn = &insns[insn_idx];
|
|
class = BPF_CLASS(insn->code);
|
|
|
|
if (++insn_processed > 32768) {
|
|
verbose("BPF program is too large. Proccessed %d insn\n",
|
|
insn_processed);
|
|
return -E2BIG;
|
|
}
|
|
|
|
err = is_state_visited(env, insn_idx);
|
|
if (err < 0)
|
|
return err;
|
|
if (err == 1) {
|
|
/* found equivalent state, can prune the search */
|
|
if (log_level) {
|
|
if (do_print_state)
|
|
verbose("\nfrom %d to %d: safe\n",
|
|
prev_insn_idx, insn_idx);
|
|
else
|
|
verbose("%d: safe\n", insn_idx);
|
|
}
|
|
goto process_bpf_exit;
|
|
}
|
|
|
|
if (log_level && do_print_state) {
|
|
verbose("\nfrom %d to %d:", prev_insn_idx, insn_idx);
|
|
print_verifier_state(env);
|
|
do_print_state = false;
|
|
}
|
|
|
|
if (log_level) {
|
|
verbose("%d: ", insn_idx);
|
|
print_bpf_insn(insn);
|
|
}
|
|
|
|
if (class == BPF_ALU || class == BPF_ALU64) {
|
|
err = check_alu_op(regs, insn);
|
|
if (err)
|
|
return err;
|
|
|
|
} else if (class == BPF_LDX) {
|
|
enum bpf_reg_type src_reg_type;
|
|
|
|
/* check for reserved fields is already done */
|
|
|
|
/* check src operand */
|
|
err = check_reg_arg(regs, insn->src_reg, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
|
|
err = check_reg_arg(regs, insn->dst_reg, DST_OP_NO_MARK);
|
|
if (err)
|
|
return err;
|
|
|
|
src_reg_type = regs[insn->src_reg].type;
|
|
|
|
/* check that memory (src_reg + off) is readable,
|
|
* the state of dst_reg will be updated by this func
|
|
*/
|
|
err = check_mem_access(env, insn->src_reg, insn->off,
|
|
BPF_SIZE(insn->code), BPF_READ,
|
|
insn->dst_reg);
|
|
if (err)
|
|
return err;
|
|
|
|
if (BPF_SIZE(insn->code) != BPF_W) {
|
|
insn_idx++;
|
|
continue;
|
|
}
|
|
|
|
if (insn->imm == 0) {
|
|
/* saw a valid insn
|
|
* dst_reg = *(u32 *)(src_reg + off)
|
|
* use reserved 'imm' field to mark this insn
|
|
*/
|
|
insn->imm = src_reg_type;
|
|
|
|
} else if (src_reg_type != insn->imm &&
|
|
(src_reg_type == PTR_TO_CTX ||
|
|
insn->imm == PTR_TO_CTX)) {
|
|
/* ABuser program is trying to use the same insn
|
|
* dst_reg = *(u32*) (src_reg + off)
|
|
* with different pointer types:
|
|
* src_reg == ctx in one branch and
|
|
* src_reg == stack|map in some other branch.
|
|
* Reject it.
|
|
*/
|
|
verbose("same insn cannot be used with different pointers\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
} else if (class == BPF_STX) {
|
|
enum bpf_reg_type dst_reg_type;
|
|
|
|
if (BPF_MODE(insn->code) == BPF_XADD) {
|
|
err = check_xadd(env, insn);
|
|
if (err)
|
|
return err;
|
|
insn_idx++;
|
|
continue;
|
|
}
|
|
|
|
/* check src1 operand */
|
|
err = check_reg_arg(regs, insn->src_reg, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
/* check src2 operand */
|
|
err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
|
|
dst_reg_type = regs[insn->dst_reg].type;
|
|
|
|
/* check that memory (dst_reg + off) is writeable */
|
|
err = check_mem_access(env, insn->dst_reg, insn->off,
|
|
BPF_SIZE(insn->code), BPF_WRITE,
|
|
insn->src_reg);
|
|
if (err)
|
|
return err;
|
|
|
|
if (insn->imm == 0) {
|
|
insn->imm = dst_reg_type;
|
|
} else if (dst_reg_type != insn->imm &&
|
|
(dst_reg_type == PTR_TO_CTX ||
|
|
insn->imm == PTR_TO_CTX)) {
|
|
verbose("same insn cannot be used with different pointers\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
} else if (class == BPF_ST) {
|
|
if (BPF_MODE(insn->code) != BPF_MEM ||
|
|
insn->src_reg != BPF_REG_0) {
|
|
verbose("BPF_ST uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
/* check src operand */
|
|
err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
|
|
/* check that memory (dst_reg + off) is writeable */
|
|
err = check_mem_access(env, insn->dst_reg, insn->off,
|
|
BPF_SIZE(insn->code), BPF_WRITE,
|
|
-1);
|
|
if (err)
|
|
return err;
|
|
|
|
} else if (class == BPF_JMP) {
|
|
u8 opcode = BPF_OP(insn->code);
|
|
|
|
if (opcode == BPF_CALL) {
|
|
if (BPF_SRC(insn->code) != BPF_K ||
|
|
insn->off != 0 ||
|
|
insn->src_reg != BPF_REG_0 ||
|
|
insn->dst_reg != BPF_REG_0) {
|
|
verbose("BPF_CALL uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
err = check_call(env, insn->imm);
|
|
if (err)
|
|
return err;
|
|
|
|
} else if (opcode == BPF_JA) {
|
|
if (BPF_SRC(insn->code) != BPF_K ||
|
|
insn->imm != 0 ||
|
|
insn->src_reg != BPF_REG_0 ||
|
|
insn->dst_reg != BPF_REG_0) {
|
|
verbose("BPF_JA uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
insn_idx += insn->off + 1;
|
|
continue;
|
|
|
|
} else if (opcode == BPF_EXIT) {
|
|
if (BPF_SRC(insn->code) != BPF_K ||
|
|
insn->imm != 0 ||
|
|
insn->src_reg != BPF_REG_0 ||
|
|
insn->dst_reg != BPF_REG_0) {
|
|
verbose("BPF_EXIT uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* eBPF calling convetion is such that R0 is used
|
|
* to return the value from eBPF program.
|
|
* Make sure that it's readable at this time
|
|
* of bpf_exit, which means that program wrote
|
|
* something into it earlier
|
|
*/
|
|
err = check_reg_arg(regs, BPF_REG_0, SRC_OP);
|
|
if (err)
|
|
return err;
|
|
|
|
process_bpf_exit:
|
|
insn_idx = pop_stack(env, &prev_insn_idx);
|
|
if (insn_idx < 0) {
|
|
break;
|
|
} else {
|
|
do_print_state = true;
|
|
continue;
|
|
}
|
|
} else {
|
|
err = check_cond_jmp_op(env, insn, &insn_idx);
|
|
if (err)
|
|
return err;
|
|
}
|
|
} else if (class == BPF_LD) {
|
|
u8 mode = BPF_MODE(insn->code);
|
|
|
|
if (mode == BPF_ABS || mode == BPF_IND) {
|
|
err = check_ld_abs(env, insn);
|
|
if (err)
|
|
return err;
|
|
|
|
} else if (mode == BPF_IMM) {
|
|
err = check_ld_imm(env, insn);
|
|
if (err)
|
|
return err;
|
|
|
|
insn_idx++;
|
|
} else {
|
|
verbose("invalid BPF_LD mode\n");
|
|
return -EINVAL;
|
|
}
|
|
} else {
|
|
verbose("unknown insn class %d\n", class);
|
|
return -EINVAL;
|
|
}
|
|
|
|
insn_idx++;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/* look for pseudo eBPF instructions that access map FDs and
|
|
* replace them with actual map pointers
|
|
*/
|
|
static int replace_map_fd_with_map_ptr(struct verifier_env *env)
|
|
{
|
|
struct bpf_insn *insn = env->prog->insnsi;
|
|
int insn_cnt = env->prog->len;
|
|
int i, j;
|
|
|
|
for (i = 0; i < insn_cnt; i++, insn++) {
|
|
if (BPF_CLASS(insn->code) == BPF_LDX &&
|
|
(BPF_MODE(insn->code) != BPF_MEM || insn->imm != 0)) {
|
|
verbose("BPF_LDX uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (BPF_CLASS(insn->code) == BPF_STX &&
|
|
((BPF_MODE(insn->code) != BPF_MEM &&
|
|
BPF_MODE(insn->code) != BPF_XADD) || insn->imm != 0)) {
|
|
verbose("BPF_STX uses reserved fields\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (insn[0].code == (BPF_LD | BPF_IMM | BPF_DW)) {
|
|
struct bpf_map *map;
|
|
struct fd f;
|
|
|
|
if (i == insn_cnt - 1 || insn[1].code != 0 ||
|
|
insn[1].dst_reg != 0 || insn[1].src_reg != 0 ||
|
|
insn[1].off != 0) {
|
|
verbose("invalid bpf_ld_imm64 insn\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (insn->src_reg == 0)
|
|
/* valid generic load 64-bit imm */
|
|
goto next_insn;
|
|
|
|
if (insn->src_reg != BPF_PSEUDO_MAP_FD) {
|
|
verbose("unrecognized bpf_ld_imm64 insn\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
f = fdget(insn->imm);
|
|
|
|
map = bpf_map_get(f);
|
|
if (IS_ERR(map)) {
|
|
verbose("fd %d is not pointing to valid bpf_map\n",
|
|
insn->imm);
|
|
fdput(f);
|
|
return PTR_ERR(map);
|
|
}
|
|
|
|
/* store map pointer inside BPF_LD_IMM64 instruction */
|
|
insn[0].imm = (u32) (unsigned long) map;
|
|
insn[1].imm = ((u64) (unsigned long) map) >> 32;
|
|
|
|
/* check whether we recorded this map already */
|
|
for (j = 0; j < env->used_map_cnt; j++)
|
|
if (env->used_maps[j] == map) {
|
|
fdput(f);
|
|
goto next_insn;
|
|
}
|
|
|
|
if (env->used_map_cnt >= MAX_USED_MAPS) {
|
|
fdput(f);
|
|
return -E2BIG;
|
|
}
|
|
|
|
/* remember this map */
|
|
env->used_maps[env->used_map_cnt++] = map;
|
|
|
|
/* hold the map. If the program is rejected by verifier,
|
|
* the map will be released by release_maps() or it
|
|
* will be used by the valid program until it's unloaded
|
|
* and all maps are released in free_bpf_prog_info()
|
|
*/
|
|
atomic_inc(&map->refcnt);
|
|
|
|
fdput(f);
|
|
next_insn:
|
|
insn++;
|
|
i++;
|
|
}
|
|
}
|
|
|
|
/* now all pseudo BPF_LD_IMM64 instructions load valid
|
|
* 'struct bpf_map *' into a register instead of user map_fd.
|
|
* These pointers will be used later by verifier to validate map access.
|
|
*/
|
|
return 0;
|
|
}
|
|
|
|
/* drop refcnt of maps used by the rejected program */
|
|
static void release_maps(struct verifier_env *env)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < env->used_map_cnt; i++)
|
|
bpf_map_put(env->used_maps[i]);
|
|
}
|
|
|
|
/* convert pseudo BPF_LD_IMM64 into generic BPF_LD_IMM64 */
|
|
static void convert_pseudo_ld_imm64(struct verifier_env *env)
|
|
{
|
|
struct bpf_insn *insn = env->prog->insnsi;
|
|
int insn_cnt = env->prog->len;
|
|
int i;
|
|
|
|
for (i = 0; i < insn_cnt; i++, insn++)
|
|
if (insn->code == (BPF_LD | BPF_IMM | BPF_DW))
|
|
insn->src_reg = 0;
|
|
}
|
|
|
|
static void adjust_branches(struct bpf_prog *prog, int pos, int delta)
|
|
{
|
|
struct bpf_insn *insn = prog->insnsi;
|
|
int insn_cnt = prog->len;
|
|
int i;
|
|
|
|
for (i = 0; i < insn_cnt; i++, insn++) {
|
|
if (BPF_CLASS(insn->code) != BPF_JMP ||
|
|
BPF_OP(insn->code) == BPF_CALL ||
|
|
BPF_OP(insn->code) == BPF_EXIT)
|
|
continue;
|
|
|
|
/* adjust offset of jmps if necessary */
|
|
if (i < pos && i + insn->off + 1 > pos)
|
|
insn->off += delta;
|
|
else if (i > pos && i + insn->off + 1 < pos)
|
|
insn->off -= delta;
|
|
}
|
|
}
|
|
|
|
/* convert load instructions that access fields of 'struct __sk_buff'
|
|
* into sequence of instructions that access fields of 'struct sk_buff'
|
|
*/
|
|
static int convert_ctx_accesses(struct verifier_env *env)
|
|
{
|
|
struct bpf_insn *insn = env->prog->insnsi;
|
|
int insn_cnt = env->prog->len;
|
|
struct bpf_insn insn_buf[16];
|
|
struct bpf_prog *new_prog;
|
|
u32 cnt;
|
|
int i;
|
|
enum bpf_access_type type;
|
|
|
|
if (!env->prog->aux->ops->convert_ctx_access)
|
|
return 0;
|
|
|
|
for (i = 0; i < insn_cnt; i++, insn++) {
|
|
if (insn->code == (BPF_LDX | BPF_MEM | BPF_W))
|
|
type = BPF_READ;
|
|
else if (insn->code == (BPF_STX | BPF_MEM | BPF_W))
|
|
type = BPF_WRITE;
|
|
else
|
|
continue;
|
|
|
|
if (insn->imm != PTR_TO_CTX) {
|
|
/* clear internal mark */
|
|
insn->imm = 0;
|
|
continue;
|
|
}
|
|
|
|
cnt = env->prog->aux->ops->
|
|
convert_ctx_access(type, insn->dst_reg, insn->src_reg,
|
|
insn->off, insn_buf);
|
|
if (cnt == 0 || cnt >= ARRAY_SIZE(insn_buf)) {
|
|
verbose("bpf verifier is misconfigured\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (cnt == 1) {
|
|
memcpy(insn, insn_buf, sizeof(*insn));
|
|
continue;
|
|
}
|
|
|
|
/* several new insns need to be inserted. Make room for them */
|
|
insn_cnt += cnt - 1;
|
|
new_prog = bpf_prog_realloc(env->prog,
|
|
bpf_prog_size(insn_cnt),
|
|
GFP_USER);
|
|
if (!new_prog)
|
|
return -ENOMEM;
|
|
|
|
new_prog->len = insn_cnt;
|
|
|
|
memmove(new_prog->insnsi + i + cnt, new_prog->insns + i + 1,
|
|
sizeof(*insn) * (insn_cnt - i - cnt));
|
|
|
|
/* copy substitute insns in place of load instruction */
|
|
memcpy(new_prog->insnsi + i, insn_buf, sizeof(*insn) * cnt);
|
|
|
|
/* adjust branches in the whole program */
|
|
adjust_branches(new_prog, i, cnt - 1);
|
|
|
|
/* keep walking new program and skip insns we just inserted */
|
|
env->prog = new_prog;
|
|
insn = new_prog->insnsi + i + cnt - 1;
|
|
i += cnt - 1;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void free_states(struct verifier_env *env)
|
|
{
|
|
struct verifier_state_list *sl, *sln;
|
|
int i;
|
|
|
|
if (!env->explored_states)
|
|
return;
|
|
|
|
for (i = 0; i < env->prog->len; i++) {
|
|
sl = env->explored_states[i];
|
|
|
|
if (sl)
|
|
while (sl != STATE_LIST_MARK) {
|
|
sln = sl->next;
|
|
kfree(sl);
|
|
sl = sln;
|
|
}
|
|
}
|
|
|
|
kfree(env->explored_states);
|
|
}
|
|
|
|
int bpf_check(struct bpf_prog **prog, union bpf_attr *attr)
|
|
{
|
|
char __user *log_ubuf = NULL;
|
|
struct verifier_env *env;
|
|
int ret = -EINVAL;
|
|
|
|
if ((*prog)->len <= 0 || (*prog)->len > BPF_MAXINSNS)
|
|
return -E2BIG;
|
|
|
|
/* 'struct verifier_env' can be global, but since it's not small,
|
|
* allocate/free it every time bpf_check() is called
|
|
*/
|
|
env = kzalloc(sizeof(struct verifier_env), GFP_KERNEL);
|
|
if (!env)
|
|
return -ENOMEM;
|
|
|
|
env->prog = *prog;
|
|
|
|
/* grab the mutex to protect few globals used by verifier */
|
|
mutex_lock(&bpf_verifier_lock);
|
|
|
|
if (attr->log_level || attr->log_buf || attr->log_size) {
|
|
/* user requested verbose verifier output
|
|
* and supplied buffer to store the verification trace
|
|
*/
|
|
log_level = attr->log_level;
|
|
log_ubuf = (char __user *) (unsigned long) attr->log_buf;
|
|
log_size = attr->log_size;
|
|
log_len = 0;
|
|
|
|
ret = -EINVAL;
|
|
/* log_* values have to be sane */
|
|
if (log_size < 128 || log_size > UINT_MAX >> 8 ||
|
|
log_level == 0 || log_ubuf == NULL)
|
|
goto free_env;
|
|
|
|
ret = -ENOMEM;
|
|
log_buf = vmalloc(log_size);
|
|
if (!log_buf)
|
|
goto free_env;
|
|
} else {
|
|
log_level = 0;
|
|
}
|
|
|
|
ret = replace_map_fd_with_map_ptr(env);
|
|
if (ret < 0)
|
|
goto skip_full_check;
|
|
|
|
env->explored_states = kcalloc(env->prog->len,
|
|
sizeof(struct verifier_state_list *),
|
|
GFP_USER);
|
|
ret = -ENOMEM;
|
|
if (!env->explored_states)
|
|
goto skip_full_check;
|
|
|
|
ret = check_cfg(env);
|
|
if (ret < 0)
|
|
goto skip_full_check;
|
|
|
|
ret = do_check(env);
|
|
|
|
skip_full_check:
|
|
while (pop_stack(env, NULL) >= 0);
|
|
free_states(env);
|
|
|
|
if (ret == 0)
|
|
/* program is valid, convert *(u32*)(ctx + off) accesses */
|
|
ret = convert_ctx_accesses(env);
|
|
|
|
if (log_level && log_len >= log_size - 1) {
|
|
BUG_ON(log_len >= log_size);
|
|
/* verifier log exceeded user supplied buffer */
|
|
ret = -ENOSPC;
|
|
/* fall through to return what was recorded */
|
|
}
|
|
|
|
/* copy verifier log back to user space including trailing zero */
|
|
if (log_level && copy_to_user(log_ubuf, log_buf, log_len + 1) != 0) {
|
|
ret = -EFAULT;
|
|
goto free_log_buf;
|
|
}
|
|
|
|
if (ret == 0 && env->used_map_cnt) {
|
|
/* if program passed verifier, update used_maps in bpf_prog_info */
|
|
env->prog->aux->used_maps = kmalloc_array(env->used_map_cnt,
|
|
sizeof(env->used_maps[0]),
|
|
GFP_KERNEL);
|
|
|
|
if (!env->prog->aux->used_maps) {
|
|
ret = -ENOMEM;
|
|
goto free_log_buf;
|
|
}
|
|
|
|
memcpy(env->prog->aux->used_maps, env->used_maps,
|
|
sizeof(env->used_maps[0]) * env->used_map_cnt);
|
|
env->prog->aux->used_map_cnt = env->used_map_cnt;
|
|
|
|
/* program is valid. Convert pseudo bpf_ld_imm64 into generic
|
|
* bpf_ld_imm64 instructions
|
|
*/
|
|
convert_pseudo_ld_imm64(env);
|
|
}
|
|
|
|
free_log_buf:
|
|
if (log_level)
|
|
vfree(log_buf);
|
|
free_env:
|
|
if (!env->prog->aux->used_maps)
|
|
/* if we didn't copy map pointers into bpf_prog_info, release
|
|
* them now. Otherwise free_bpf_prog_info() will release them.
|
|
*/
|
|
release_maps(env);
|
|
*prog = env->prog;
|
|
kfree(env);
|
|
mutex_unlock(&bpf_verifier_lock);
|
|
return ret;
|
|
}
|