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alistair23-linux/net/core/filter.c
Daniel Borkmann 8c482cdc35 net: filter: seccomp: fix wrong decoding of BPF_S_ANC_SECCOMP_LD_W 
While reviewing seccomp code, we found that BPF_S_ANC_SECCOMP_LD_W has
been wrongly decoded by commit a8fc927780 ("sk-filter: Add ability to
get socket filter program (v2)") into the opcode BPF_LD|BPF_B|BPF_ABS
although it should have been decoded as BPF_LD|BPF_W|BPF_ABS.

In practice, this should not have much side-effect though, as such
conversion is/was being done through prctl(2) PR_SET_SECCOMP. Reverse
operation PR_GET_SECCOMP will only return the current seccomp mode, but
not the filter itself. Since the transition to the new BPF infrastructure,
it's also not used anymore, so we can simply remove this as it's
unreachable.

Fixes: a8fc927780 ("sk-filter: Add ability to get socket filter program (v2)")
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2014-04-14 16:26:47 -04:00

1825 lines
46 KiB
C
Raw Blame History

/*
* Linux Socket Filter - Kernel level socket filtering
*
* Based on the design of the Berkeley Packet Filter. The new
* internal format has been designed by PLUMgrid:
*
* Copyright (c) 2011 - 2014 PLUMgrid, http://plumgrid.com
*
* Authors:
*
* Jay Schulist <jschlst@samba.org>
* Alexei Starovoitov <ast@plumgrid.com>
* Daniel Borkmann <dborkman@redhat.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* Andi Kleen - Fix a few bad bugs and races.
* Kris Katterjohn - Added many additional checks in sk_chk_filter()
*/
#include <linux/module.h>
#include <linux/types.h>
#include <linux/mm.h>
#include <linux/fcntl.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/if_packet.h>
#include <linux/gfp.h>
#include <net/ip.h>
#include <net/protocol.h>
#include <net/netlink.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <linux/errno.h>
#include <linux/timer.h>
#include <asm/uaccess.h>
#include <asm/unaligned.h>
#include <linux/filter.h>
#include <linux/ratelimit.h>
#include <linux/seccomp.h>
#include <linux/if_vlan.h>
/* No hurry in this branch
*
* Exported for the bpf jit load helper.
*/
void *bpf_internal_load_pointer_neg_helper(const struct sk_buff *skb, int k, unsigned int size)
{
u8 *ptr = NULL;
if (k >= SKF_NET_OFF)
ptr = skb_network_header(skb) + k - SKF_NET_OFF;
else if (k >= SKF_LL_OFF)
ptr = skb_mac_header(skb) + k - SKF_LL_OFF;
if (ptr >= skb->head && ptr + size <= skb_tail_pointer(skb))
return ptr;
return NULL;
}
static inline void *load_pointer(const struct sk_buff *skb, int k,
unsigned int size, void *buffer)
{
if (k >= 0)
return skb_header_pointer(skb, k, size, buffer);
return bpf_internal_load_pointer_neg_helper(skb, k, size);
}
/**
* sk_filter - run a packet through a socket filter
* @sk: sock associated with &sk_buff
* @skb: buffer to filter
*
* Run the filter code and then cut skb->data to correct size returned by
* sk_run_filter. If pkt_len is 0 we toss packet. If skb->len is smaller
* than pkt_len we keep whole skb->data. This is the socket level
* wrapper to sk_run_filter. It returns 0 if the packet should
* be accepted or -EPERM if the packet should be tossed.
*
*/
int sk_filter(struct sock *sk, struct sk_buff *skb)
{
int err;
struct sk_filter *filter;
/*
* If the skb was allocated from pfmemalloc reserves, only
* allow SOCK_MEMALLOC sockets to use it as this socket is
* helping free memory
*/
if (skb_pfmemalloc(skb) && !sock_flag(sk, SOCK_MEMALLOC))
return -ENOMEM;
err = security_sock_rcv_skb(sk, skb);
if (err)
return err;
rcu_read_lock();
filter = rcu_dereference(sk->sk_filter);
if (filter) {
unsigned int pkt_len = SK_RUN_FILTER(filter, skb);
err = pkt_len ? pskb_trim(skb, pkt_len) : -EPERM;
}
rcu_read_unlock();
return err;
}
EXPORT_SYMBOL(sk_filter);
/* Base function for offset calculation. Needs to go into .text section,
* therefore keeping it non-static as well; will also be used by JITs
* anyway later on, so do not let the compiler omit it.
*/
noinline u64 __bpf_call_base(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
{
return 0;
}
/**
* __sk_run_filter - run a filter on a given context
* @ctx: buffer to run the filter on
* @insn: filter to apply
*
* Decode and apply filter instructions to the skb->data. Return length to
* keep, 0 for none. @ctx is the data we are operating on, @insn is the
* array of filter instructions.
*/
unsigned int __sk_run_filter(void *ctx, const struct sock_filter_int *insn)
{
u64 stack[MAX_BPF_STACK / sizeof(u64)];
u64 regs[MAX_BPF_REG], tmp;
void *ptr;
int off;
#define K insn->imm
#define A regs[insn->a_reg]
#define X regs[insn->x_reg]
#define R0 regs[0]
#define CONT ({insn++; goto select_insn; })
#define CONT_JMP ({insn++; goto select_insn; })
static const void *jumptable[256] = {
[0 ... 255] = &&default_label,
/* Now overwrite non-defaults ... */
#define DL(A, B, C) [A|B|C] = &&A##_##B##_##C
DL(BPF_ALU, BPF_ADD, BPF_X),
DL(BPF_ALU, BPF_ADD, BPF_K),
DL(BPF_ALU, BPF_SUB, BPF_X),
DL(BPF_ALU, BPF_SUB, BPF_K),
DL(BPF_ALU, BPF_AND, BPF_X),
DL(BPF_ALU, BPF_AND, BPF_K),
DL(BPF_ALU, BPF_OR, BPF_X),
DL(BPF_ALU, BPF_OR, BPF_K),
DL(BPF_ALU, BPF_LSH, BPF_X),
DL(BPF_ALU, BPF_LSH, BPF_K),
DL(BPF_ALU, BPF_RSH, BPF_X),
DL(BPF_ALU, BPF_RSH, BPF_K),
DL(BPF_ALU, BPF_XOR, BPF_X),
DL(BPF_ALU, BPF_XOR, BPF_K),
DL(BPF_ALU, BPF_MUL, BPF_X),
DL(BPF_ALU, BPF_MUL, BPF_K),
DL(BPF_ALU, BPF_MOV, BPF_X),
DL(BPF_ALU, BPF_MOV, BPF_K),
DL(BPF_ALU, BPF_DIV, BPF_X),
DL(BPF_ALU, BPF_DIV, BPF_K),
DL(BPF_ALU, BPF_MOD, BPF_X),
DL(BPF_ALU, BPF_MOD, BPF_K),
DL(BPF_ALU, BPF_NEG, 0),
DL(BPF_ALU, BPF_END, BPF_TO_BE),
DL(BPF_ALU, BPF_END, BPF_TO_LE),
DL(BPF_ALU64, BPF_ADD, BPF_X),
DL(BPF_ALU64, BPF_ADD, BPF_K),
DL(BPF_ALU64, BPF_SUB, BPF_X),
DL(BPF_ALU64, BPF_SUB, BPF_K),
DL(BPF_ALU64, BPF_AND, BPF_X),
DL(BPF_ALU64, BPF_AND, BPF_K),
DL(BPF_ALU64, BPF_OR, BPF_X),
DL(BPF_ALU64, BPF_OR, BPF_K),
DL(BPF_ALU64, BPF_LSH, BPF_X),
DL(BPF_ALU64, BPF_LSH, BPF_K),
DL(BPF_ALU64, BPF_RSH, BPF_X),
DL(BPF_ALU64, BPF_RSH, BPF_K),
DL(BPF_ALU64, BPF_XOR, BPF_X),
DL(BPF_ALU64, BPF_XOR, BPF_K),
DL(BPF_ALU64, BPF_MUL, BPF_X),
DL(BPF_ALU64, BPF_MUL, BPF_K),
DL(BPF_ALU64, BPF_MOV, BPF_X),
DL(BPF_ALU64, BPF_MOV, BPF_K),
DL(BPF_ALU64, BPF_ARSH, BPF_X),
DL(BPF_ALU64, BPF_ARSH, BPF_K),
DL(BPF_ALU64, BPF_DIV, BPF_X),
DL(BPF_ALU64, BPF_DIV, BPF_K),
DL(BPF_ALU64, BPF_MOD, BPF_X),
DL(BPF_ALU64, BPF_MOD, BPF_K),
DL(BPF_ALU64, BPF_NEG, 0),
DL(BPF_JMP, BPF_CALL, 0),
DL(BPF_JMP, BPF_JA, 0),
DL(BPF_JMP, BPF_JEQ, BPF_X),
DL(BPF_JMP, BPF_JEQ, BPF_K),
DL(BPF_JMP, BPF_JNE, BPF_X),
DL(BPF_JMP, BPF_JNE, BPF_K),
DL(BPF_JMP, BPF_JGT, BPF_X),
DL(BPF_JMP, BPF_JGT, BPF_K),
DL(BPF_JMP, BPF_JGE, BPF_X),
DL(BPF_JMP, BPF_JGE, BPF_K),
DL(BPF_JMP, BPF_JSGT, BPF_X),
DL(BPF_JMP, BPF_JSGT, BPF_K),
DL(BPF_JMP, BPF_JSGE, BPF_X),
DL(BPF_JMP, BPF_JSGE, BPF_K),
DL(BPF_JMP, BPF_JSET, BPF_X),
DL(BPF_JMP, BPF_JSET, BPF_K),
DL(BPF_JMP, BPF_EXIT, 0),
DL(BPF_STX, BPF_MEM, BPF_B),
DL(BPF_STX, BPF_MEM, BPF_H),
DL(BPF_STX, BPF_MEM, BPF_W),
DL(BPF_STX, BPF_MEM, BPF_DW),
DL(BPF_STX, BPF_XADD, BPF_W),
DL(BPF_STX, BPF_XADD, BPF_DW),
DL(BPF_ST, BPF_MEM, BPF_B),
DL(BPF_ST, BPF_MEM, BPF_H),
DL(BPF_ST, BPF_MEM, BPF_W),
DL(BPF_ST, BPF_MEM, BPF_DW),
DL(BPF_LDX, BPF_MEM, BPF_B),
DL(BPF_LDX, BPF_MEM, BPF_H),
DL(BPF_LDX, BPF_MEM, BPF_W),
DL(BPF_LDX, BPF_MEM, BPF_DW),
DL(BPF_LD, BPF_ABS, BPF_W),
DL(BPF_LD, BPF_ABS, BPF_H),
DL(BPF_LD, BPF_ABS, BPF_B),
DL(BPF_LD, BPF_IND, BPF_W),
DL(BPF_LD, BPF_IND, BPF_H),
DL(BPF_LD, BPF_IND, BPF_B),
#undef DL
};
regs[FP_REG] = (u64) (unsigned long) &stack[ARRAY_SIZE(stack)];
regs[ARG1_REG] = (u64) (unsigned long) ctx;
select_insn:
goto *jumptable[insn->code];
/* ALU */
#define ALU(OPCODE, OP) \
BPF_ALU64_##OPCODE##_BPF_X: \
A = A OP X; \
CONT; \
BPF_ALU_##OPCODE##_BPF_X: \
A = (u32) A OP (u32) X; \
CONT; \
BPF_ALU64_##OPCODE##_BPF_K: \
A = A OP K; \
CONT; \
BPF_ALU_##OPCODE##_BPF_K: \
A = (u32) A OP (u32) K; \
CONT;
ALU(BPF_ADD, +)
ALU(BPF_SUB, -)
ALU(BPF_AND, &)
ALU(BPF_OR, |)
ALU(BPF_LSH, <<)
ALU(BPF_RSH, >>)
ALU(BPF_XOR, ^)
ALU(BPF_MUL, *)
#undef ALU
BPF_ALU_BPF_NEG_0:
A = (u32) -A;
CONT;
BPF_ALU64_BPF_NEG_0:
A = -A;
CONT;
BPF_ALU_BPF_MOV_BPF_X:
A = (u32) X;
CONT;
BPF_ALU_BPF_MOV_BPF_K:
A = (u32) K;
CONT;
BPF_ALU64_BPF_MOV_BPF_X:
A = X;
CONT;
BPF_ALU64_BPF_MOV_BPF_K:
A = K;
CONT;
BPF_ALU64_BPF_ARSH_BPF_X:
(*(s64 *) &A) >>= X;
CONT;
BPF_ALU64_BPF_ARSH_BPF_K:
(*(s64 *) &A) >>= K;
CONT;
BPF_ALU64_BPF_MOD_BPF_X:
if (unlikely(X == 0))
return 0;
tmp = A;
A = do_div(tmp, X);
CONT;
BPF_ALU_BPF_MOD_BPF_X:
if (unlikely(X == 0))
return 0;
tmp = (u32) A;
A = do_div(tmp, (u32) X);
CONT;
BPF_ALU64_BPF_MOD_BPF_K:
tmp = A;
A = do_div(tmp, K);
CONT;
BPF_ALU_BPF_MOD_BPF_K:
tmp = (u32) A;
A = do_div(tmp, (u32) K);
CONT;
BPF_ALU64_BPF_DIV_BPF_X:
if (unlikely(X == 0))
return 0;
do_div(A, X);
CONT;
BPF_ALU_BPF_DIV_BPF_X:
if (unlikely(X == 0))
return 0;
tmp = (u32) A;
do_div(tmp, (u32) X);
A = (u32) tmp;
CONT;
BPF_ALU64_BPF_DIV_BPF_K:
do_div(A, K);
CONT;
BPF_ALU_BPF_DIV_BPF_K:
tmp = (u32) A;
do_div(tmp, (u32) K);
A = (u32) tmp;
CONT;
BPF_ALU_BPF_END_BPF_TO_BE:
switch (K) {
case 16:
A = (__force u16) cpu_to_be16(A);
break;
case 32:
A = (__force u32) cpu_to_be32(A);
break;
case 64:
A = (__force u64) cpu_to_be64(A);
break;
}
CONT;
BPF_ALU_BPF_END_BPF_TO_LE:
switch (K) {
case 16:
A = (__force u16) cpu_to_le16(A);
break;
case 32:
A = (__force u32) cpu_to_le32(A);
break;
case 64:
A = (__force u64) cpu_to_le64(A);
break;
}
CONT;
/* CALL */
BPF_JMP_BPF_CALL_0:
/* Function call scratches R1-R5 registers, preserves R6-R9,
* and stores return value into R0.
*/
R0 = (__bpf_call_base + insn->imm)(regs[1], regs[2], regs[3],
regs[4], regs[5]);
CONT;
/* JMP */
BPF_JMP_BPF_JA_0:
insn += insn->off;
CONT;
BPF_JMP_BPF_JEQ_BPF_X:
if (A == X) {
insn += insn->off;
CONT_JMP;
}
CONT;
BPF_JMP_BPF_JEQ_BPF_K:
if (A == K) {
insn += insn->off;
CONT_JMP;
}
CONT;
BPF_JMP_BPF_JNE_BPF_X:
if (A != X) {
insn += insn->off;
CONT_JMP;
}
CONT;
BPF_JMP_BPF_JNE_BPF_K:
if (A != K) {
insn += insn->off;
CONT_JMP;
}
CONT;
BPF_JMP_BPF_JGT_BPF_X:
if (A > X) {
insn += insn->off;
CONT_JMP;
}
CONT;
BPF_JMP_BPF_JGT_BPF_K:
if (A > K) {
insn += insn->off;
CONT_JMP;
}
CONT;
BPF_JMP_BPF_JGE_BPF_X:
if (A >= X) {
insn += insn->off;
CONT_JMP;
}
CONT;
BPF_JMP_BPF_JGE_BPF_K:
if (A >= K) {
insn += insn->off;
CONT_JMP;
}
CONT;
BPF_JMP_BPF_JSGT_BPF_X:
if (((s64)A) > ((s64)X)) {
insn += insn->off;
CONT_JMP;
}
CONT;
BPF_JMP_BPF_JSGT_BPF_K:
if (((s64)A) > ((s64)K)) {
insn += insn->off;
CONT_JMP;
}
CONT;
BPF_JMP_BPF_JSGE_BPF_X:
if (((s64)A) >= ((s64)X)) {
insn += insn->off;
CONT_JMP;
}
CONT;
BPF_JMP_BPF_JSGE_BPF_K:
if (((s64)A) >= ((s64)K)) {
insn += insn->off;
CONT_JMP;
}
CONT;
BPF_JMP_BPF_JSET_BPF_X:
if (A & X) {
insn += insn->off;
CONT_JMP;
}
CONT;
BPF_JMP_BPF_JSET_BPF_K:
if (A & K) {
insn += insn->off;
CONT_JMP;
}
CONT;
BPF_JMP_BPF_EXIT_0:
return R0;
/* STX and ST and LDX*/
#define LDST(SIZEOP, SIZE) \
BPF_STX_BPF_MEM_##SIZEOP: \
*(SIZE *)(unsigned long) (A + insn->off) = X; \
CONT; \
BPF_ST_BPF_MEM_##SIZEOP: \
*(SIZE *)(unsigned long) (A + insn->off) = K; \
CONT; \
BPF_LDX_BPF_MEM_##SIZEOP: \
A = *(SIZE *)(unsigned long) (X + insn->off); \
CONT;
LDST(BPF_B, u8)
LDST(BPF_H, u16)
LDST(BPF_W, u32)
LDST(BPF_DW, u64)
#undef LDST
BPF_STX_BPF_XADD_BPF_W: /* lock xadd *(u32 *)(A + insn->off) += X */
atomic_add((u32) X, (atomic_t *)(unsigned long)
(A + insn->off));
CONT;
BPF_STX_BPF_XADD_BPF_DW: /* lock xadd *(u64 *)(A + insn->off) += X */
atomic64_add((u64) X, (atomic64_t *)(unsigned long)
(A + insn->off));
CONT;
BPF_LD_BPF_ABS_BPF_W: /* R0 = ntohl(*(u32 *) (skb->data + K)) */
off = K;
load_word:
/* BPF_LD + BPD_ABS and BPF_LD + BPF_IND insns are only
* appearing in the programs where ctx == skb. All programs
* keep 'ctx' in regs[CTX_REG] == R6, sk_convert_filter()
* saves it in R6, internal BPF verifier will check that
* R6 == ctx.
*
* BPF_ABS and BPF_IND are wrappers of function calls, so
* they scratch R1-R5 registers, preserve R6-R9, and store
* return value into R0.
*
* Implicit input:
* ctx
*
* Explicit input:
* X == any register
* K == 32-bit immediate
*
* Output:
* R0 - 8/16/32-bit skb data converted to cpu endianness
*/
ptr = load_pointer((struct sk_buff *) ctx, off, 4, &tmp);
if (likely(ptr != NULL)) {
R0 = get_unaligned_be32(ptr);
CONT;
}
return 0;
BPF_LD_BPF_ABS_BPF_H: /* R0 = ntohs(*(u16 *) (skb->data + K)) */
off = K;
load_half:
ptr = load_pointer((struct sk_buff *) ctx, off, 2, &tmp);
if (likely(ptr != NULL)) {
R0 = get_unaligned_be16(ptr);
CONT;
}
return 0;
BPF_LD_BPF_ABS_BPF_B: /* R0 = *(u8 *) (ctx + K) */
off = K;
load_byte:
ptr = load_pointer((struct sk_buff *) ctx, off, 1, &tmp);
if (likely(ptr != NULL)) {
R0 = *(u8 *)ptr;
CONT;
}
return 0;
BPF_LD_BPF_IND_BPF_W: /* R0 = ntohl(*(u32 *) (skb->data + X + K)) */
off = K + X;
goto load_word;
BPF_LD_BPF_IND_BPF_H: /* R0 = ntohs(*(u16 *) (skb->data + X + K)) */
off = K + X;
goto load_half;
BPF_LD_BPF_IND_BPF_B: /* R0 = *(u8 *) (skb->data + X + K) */
off = K + X;
goto load_byte;
default_label:
/* If we ever reach this, we have a bug somewhere. */
WARN_RATELIMIT(1, "unknown opcode %02x\n", insn->code);
return 0;
#undef CONT_JMP
#undef CONT
#undef R0
#undef X
#undef A
#undef K
}
u32 sk_run_filter_int_seccomp(const struct seccomp_data *ctx,
const struct sock_filter_int *insni)
__attribute__ ((alias ("__sk_run_filter")));
u32 sk_run_filter_int_skb(const struct sk_buff *ctx,
const struct sock_filter_int *insni)
__attribute__ ((alias ("__sk_run_filter")));
EXPORT_SYMBOL_GPL(sk_run_filter_int_skb);
/* Helper to find the offset of pkt_type in sk_buff structure. We want
* to make sure its still a 3bit field starting at a byte boundary;
* taken from arch/x86/net/bpf_jit_comp.c.
*/
#define PKT_TYPE_MAX 7
static unsigned int pkt_type_offset(void)
{
struct sk_buff skb_probe = { .pkt_type = ~0, };
u8 *ct = (u8 *) &skb_probe;
unsigned int off;
for (off = 0; off < sizeof(struct sk_buff); off++) {
if (ct[off] == PKT_TYPE_MAX)
return off;
}
pr_err_once("Please fix %s, as pkt_type couldn't be found!\n", __func__);
return -1;
}
static u64 __skb_get_pay_offset(u64 ctx, u64 A, u64 X, u64 r4, u64 r5)
{
struct sk_buff *skb = (struct sk_buff *)(long) ctx;
return __skb_get_poff(skb);
}
static u64 __skb_get_nlattr(u64 ctx, u64 A, u64 X, u64 r4, u64 r5)
{
struct sk_buff *skb = (struct sk_buff *)(long) ctx;
struct nlattr *nla;
if (skb_is_nonlinear(skb))
return 0;
if (skb->len < sizeof(struct nlattr))
return 0;
if (A > skb->len - sizeof(struct nlattr))
return 0;
nla = nla_find((struct nlattr *) &skb->data[A], skb->len - A, X);
if (nla)
return (void *) nla - (void *) skb->data;
return 0;
}
static u64 __skb_get_nlattr_nest(u64 ctx, u64 A, u64 X, u64 r4, u64 r5)
{
struct sk_buff *skb = (struct sk_buff *)(long) ctx;
struct nlattr *nla;
if (skb_is_nonlinear(skb))
return 0;
if (skb->len < sizeof(struct nlattr))
return 0;
if (A > skb->len - sizeof(struct nlattr))
return 0;
nla = (struct nlattr *) &skb->data[A];
if (nla->nla_len > skb->len - A)
return 0;
nla = nla_find_nested(nla, X);
if (nla)
return (void *) nla - (void *) skb->data;
return 0;
}
static u64 __get_raw_cpu_id(u64 ctx, u64 A, u64 X, u64 r4, u64 r5)
{
return raw_smp_processor_id();
}
/* Register mappings for user programs. */
#define A_REG 0
#define X_REG 7
#define TMP_REG 8
#define ARG2_REG 2
#define ARG3_REG 3
static bool convert_bpf_extensions(struct sock_filter *fp,
struct sock_filter_int **insnp)
{
struct sock_filter_int *insn = *insnp;
switch (fp->k) {
case SKF_AD_OFF + SKF_AD_PROTOCOL:
BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, protocol) != 2);
insn->code = BPF_LDX | BPF_MEM | BPF_H;
insn->a_reg = A_REG;
insn->x_reg = CTX_REG;
insn->off = offsetof(struct sk_buff, protocol);
insn++;
/* A = ntohs(A) [emitting a nop or swap16] */
insn->code = BPF_ALU | BPF_END | BPF_FROM_BE;
insn->a_reg = A_REG;
insn->imm = 16;
break;
case SKF_AD_OFF + SKF_AD_PKTTYPE:
insn->code = BPF_LDX | BPF_MEM | BPF_B;
insn->a_reg = A_REG;
insn->x_reg = CTX_REG;
insn->off = pkt_type_offset();
if (insn->off < 0)
return false;
insn++;
insn->code = BPF_ALU | BPF_AND | BPF_K;
insn->a_reg = A_REG;
insn->imm = PKT_TYPE_MAX;
break;
case SKF_AD_OFF + SKF_AD_IFINDEX:
case SKF_AD_OFF + SKF_AD_HATYPE:
if (FIELD_SIZEOF(struct sk_buff, dev) == 8)
insn->code = BPF_LDX | BPF_MEM | BPF_DW;
else
insn->code = BPF_LDX | BPF_MEM | BPF_W;
insn->a_reg = TMP_REG;
insn->x_reg = CTX_REG;
insn->off = offsetof(struct sk_buff, dev);
insn++;
insn->code = BPF_JMP | BPF_JNE | BPF_K;
insn->a_reg = TMP_REG;
insn->imm = 0;
insn->off = 1;
insn++;
insn->code = BPF_JMP | BPF_EXIT;
insn++;
BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, ifindex) != 4);
BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, type) != 2);
insn->a_reg = A_REG;
insn->x_reg = TMP_REG;
if (fp->k == SKF_AD_OFF + SKF_AD_IFINDEX) {
insn->code = BPF_LDX | BPF_MEM | BPF_W;
insn->off = offsetof(struct net_device, ifindex);
} else {
insn->code = BPF_LDX | BPF_MEM | BPF_H;
insn->off = offsetof(struct net_device, type);
}
break;
case SKF_AD_OFF + SKF_AD_MARK:
BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, mark) != 4);
insn->code = BPF_LDX | BPF_MEM | BPF_W;
insn->a_reg = A_REG;
insn->x_reg = CTX_REG;
insn->off = offsetof(struct sk_buff, mark);
break;
case SKF_AD_OFF + SKF_AD_RXHASH:
BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, hash) != 4);
insn->code = BPF_LDX | BPF_MEM | BPF_W;
insn->a_reg = A_REG;
insn->x_reg = CTX_REG;
insn->off = offsetof(struct sk_buff, hash);
break;
case SKF_AD_OFF + SKF_AD_QUEUE:
BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, queue_mapping) != 2);
insn->code = BPF_LDX | BPF_MEM | BPF_H;
insn->a_reg = A_REG;
insn->x_reg = CTX_REG;
insn->off = offsetof(struct sk_buff, queue_mapping);
break;
case SKF_AD_OFF + SKF_AD_VLAN_TAG:
case SKF_AD_OFF + SKF_AD_VLAN_TAG_PRESENT:
BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, vlan_tci) != 2);
insn->code = BPF_LDX | BPF_MEM | BPF_H;
insn->a_reg = A_REG;
insn->x_reg = CTX_REG;
insn->off = offsetof(struct sk_buff, vlan_tci);
insn++;
BUILD_BUG_ON(VLAN_TAG_PRESENT != 0x1000);
if (fp->k == SKF_AD_OFF + SKF_AD_VLAN_TAG) {
insn->code = BPF_ALU | BPF_AND | BPF_K;
insn->a_reg = A_REG;
insn->imm = ~VLAN_TAG_PRESENT;
} else {
insn->code = BPF_ALU | BPF_RSH | BPF_K;
insn->a_reg = A_REG;
insn->imm = 12;
insn++;
insn->code = BPF_ALU | BPF_AND | BPF_K;
insn->a_reg = A_REG;
insn->imm = 1;
}
break;
case SKF_AD_OFF + SKF_AD_PAY_OFFSET:
case SKF_AD_OFF + SKF_AD_NLATTR:
case SKF_AD_OFF + SKF_AD_NLATTR_NEST:
case SKF_AD_OFF + SKF_AD_CPU:
/* arg1 = ctx */
insn->code = BPF_ALU64 | BPF_MOV | BPF_X;
insn->a_reg = ARG1_REG;
insn->x_reg = CTX_REG;
insn++;
/* arg2 = A */
insn->code = BPF_ALU64 | BPF_MOV | BPF_X;
insn->a_reg = ARG2_REG;
insn->x_reg = A_REG;
insn++;
/* arg3 = X */
insn->code = BPF_ALU64 | BPF_MOV | BPF_X;
insn->a_reg = ARG3_REG;
insn->x_reg = X_REG;
insn++;
/* Emit call(ctx, arg2=A, arg3=X) */
insn->code = BPF_JMP | BPF_CALL;
switch (fp->k) {
case SKF_AD_OFF + SKF_AD_PAY_OFFSET:
insn->imm = __skb_get_pay_offset - __bpf_call_base;
break;
case SKF_AD_OFF + SKF_AD_NLATTR:
insn->imm = __skb_get_nlattr - __bpf_call_base;
break;
case SKF_AD_OFF + SKF_AD_NLATTR_NEST:
insn->imm = __skb_get_nlattr_nest - __bpf_call_base;
break;
case SKF_AD_OFF + SKF_AD_CPU:
insn->imm = __get_raw_cpu_id - __bpf_call_base;
break;
}
break;
case SKF_AD_OFF + SKF_AD_ALU_XOR_X:
insn->code = BPF_ALU | BPF_XOR | BPF_X;
insn->a_reg = A_REG;
insn->x_reg = X_REG;
break;
default:
/* This is just a dummy call to avoid letting the compiler
* evict __bpf_call_base() as an optimization. Placed here
* where no-one bothers.
*/
BUG_ON(__bpf_call_base(0, 0, 0, 0, 0) != 0);
return false;
}
*insnp = insn;
return true;
}
/**
* sk_convert_filter - convert filter program
* @prog: the user passed filter program
* @len: the length of the user passed filter program
* @new_prog: buffer where converted program will be stored
* @new_len: pointer to store length of converted program
*
* Remap 'sock_filter' style BPF instruction set to 'sock_filter_ext' style.
* Conversion workflow:
*
* 1) First pass for calculating the new program length:
* sk_convert_filter(old_prog, old_len, NULL, &new_len)
*
* 2) 2nd pass to remap in two passes: 1st pass finds new
* jump offsets, 2nd pass remapping:
* new_prog = kmalloc(sizeof(struct sock_filter_int) * new_len);
* sk_convert_filter(old_prog, old_len, new_prog, &new_len);
*
* User BPF's register A is mapped to our BPF register 6, user BPF
* register X is mapped to BPF register 7; frame pointer is always
* register 10; Context 'void *ctx' is stored in register 1, that is,
* for socket filters: ctx == 'struct sk_buff *', for seccomp:
* ctx == 'struct seccomp_data *'.
*/
int sk_convert_filter(struct sock_filter *prog, int len,
struct sock_filter_int *new_prog, int *new_len)
{
int new_flen = 0, pass = 0, target, i;
struct sock_filter_int *new_insn;
struct sock_filter *fp;
int *addrs = NULL;
u8 bpf_src;
BUILD_BUG_ON(BPF_MEMWORDS * sizeof(u32) > MAX_BPF_STACK);
BUILD_BUG_ON(FP_REG + 1 != MAX_BPF_REG);
if (len <= 0 || len >= BPF_MAXINSNS)
return -EINVAL;
if (new_prog) {
addrs = kzalloc(len * sizeof(*addrs), GFP_KERNEL);
if (!addrs)
return -ENOMEM;
}
do_pass:
new_insn = new_prog;
fp = prog;
if (new_insn) {
new_insn->code = BPF_ALU64 | BPF_MOV | BPF_X;
new_insn->a_reg = CTX_REG;
new_insn->x_reg = ARG1_REG;
}
new_insn++;
for (i = 0; i < len; fp++, i++) {
struct sock_filter_int tmp_insns[6] = { };
struct sock_filter_int *insn = tmp_insns;
if (addrs)
addrs[i] = new_insn - new_prog;
switch (fp->code) {
/* All arithmetic insns and skb loads map as-is. */
case BPF_ALU | BPF_ADD | BPF_X:
case BPF_ALU | BPF_ADD | BPF_K:
case BPF_ALU | BPF_SUB | BPF_X:
case BPF_ALU | BPF_SUB | BPF_K:
case BPF_ALU | BPF_AND | BPF_X:
case BPF_ALU | BPF_AND | BPF_K:
case BPF_ALU | BPF_OR | BPF_X:
case BPF_ALU | BPF_OR | BPF_K:
case BPF_ALU | BPF_LSH | BPF_X:
case BPF_ALU | BPF_LSH | BPF_K:
case BPF_ALU | BPF_RSH | BPF_X:
case BPF_ALU | BPF_RSH | BPF_K:
case BPF_ALU | BPF_XOR | BPF_X:
case BPF_ALU | BPF_XOR | BPF_K:
case BPF_ALU | BPF_MUL | BPF_X:
case BPF_ALU | BPF_MUL | BPF_K:
case BPF_ALU | BPF_DIV | BPF_X:
case BPF_ALU | BPF_DIV | BPF_K:
case BPF_ALU | BPF_MOD | BPF_X:
case BPF_ALU | BPF_MOD | BPF_K:
case BPF_ALU | BPF_NEG:
case BPF_LD | BPF_ABS | BPF_W:
case BPF_LD | BPF_ABS | BPF_H:
case BPF_LD | BPF_ABS | BPF_B:
case BPF_LD | BPF_IND | BPF_W:
case BPF_LD | BPF_IND | BPF_H:
case BPF_LD | BPF_IND | BPF_B:
/* Check for overloaded BPF extension and
* directly convert it if found, otherwise
* just move on with mapping.
*/
if (BPF_CLASS(fp->code) == BPF_LD &&
BPF_MODE(fp->code) == BPF_ABS &&
convert_bpf_extensions(fp, &insn))
break;
insn->code = fp->code;
insn->a_reg = A_REG;
insn->x_reg = X_REG;
insn->imm = fp->k;
break;
/* Jump opcodes map as-is, but offsets need adjustment. */
case BPF_JMP | BPF_JA:
target = i + fp->k + 1;
insn->code = fp->code;
#define EMIT_JMP \
do { \
if (target >= len || target < 0) \
goto err; \
insn->off = addrs ? addrs[target] - addrs[i] - 1 : 0; \
/* Adjust pc relative offset for 2nd or 3rd insn. */ \
insn->off -= insn - tmp_insns; \
} while (0)
EMIT_JMP;
break;
case BPF_JMP | BPF_JEQ | BPF_K:
case BPF_JMP | BPF_JEQ | BPF_X:
case BPF_JMP | BPF_JSET | BPF_K:
case BPF_JMP | BPF_JSET | BPF_X:
case BPF_JMP | BPF_JGT | BPF_K:
case BPF_JMP | BPF_JGT | BPF_X:
case BPF_JMP | BPF_JGE | BPF_K:
case BPF_JMP | BPF_JGE | BPF_X:
if (BPF_SRC(fp->code) == BPF_K && (int) fp->k < 0) {
/* BPF immediates are signed, zero extend
* immediate into tmp register and use it
* in compare insn.
*/
insn->code = BPF_ALU | BPF_MOV | BPF_K;
insn->a_reg = TMP_REG;
insn->imm = fp->k;
insn++;
insn->a_reg = A_REG;
insn->x_reg = TMP_REG;
bpf_src = BPF_X;
} else {
insn->a_reg = A_REG;
insn->x_reg = X_REG;
insn->imm = fp->k;
bpf_src = BPF_SRC(fp->code);
}
/* Common case where 'jump_false' is next insn. */
if (fp->jf == 0) {
insn->code = BPF_JMP | BPF_OP(fp->code) | bpf_src;
target = i + fp->jt + 1;
EMIT_JMP;
break;
}
/* Convert JEQ into JNE when 'jump_true' is next insn. */
if (fp->jt == 0 && BPF_OP(fp->code) == BPF_JEQ) {
insn->code = BPF_JMP | BPF_JNE | bpf_src;
target = i + fp->jf + 1;
EMIT_JMP;
break;
}
/* Other jumps are mapped into two insns: Jxx and JA. */
target = i + fp->jt + 1;
insn->code = BPF_JMP | BPF_OP(fp->code) | bpf_src;
EMIT_JMP;
insn++;
insn->code = BPF_JMP | BPF_JA;
target = i + fp->jf + 1;
EMIT_JMP;
break;
/* ldxb 4 * ([14] & 0xf) is remaped into 6 insns. */
case BPF_LDX | BPF_MSH | BPF_B:
insn->code = BPF_ALU64 | BPF_MOV | BPF_X;
insn->a_reg = TMP_REG;
insn->x_reg = A_REG;
insn++;
insn->code = BPF_LD | BPF_ABS | BPF_B;
insn->a_reg = A_REG;
insn->imm = fp->k;
insn++;
insn->code = BPF_ALU | BPF_AND | BPF_K;
insn->a_reg = A_REG;
insn->imm = 0xf;
insn++;
insn->code = BPF_ALU | BPF_LSH | BPF_K;
insn->a_reg = A_REG;
insn->imm = 2;
insn++;
insn->code = BPF_ALU64 | BPF_MOV | BPF_X;
insn->a_reg = X_REG;
insn->x_reg = A_REG;
insn++;
insn->code = BPF_ALU64 | BPF_MOV | BPF_X;
insn->a_reg = A_REG;
insn->x_reg = TMP_REG;
break;
/* RET_K, RET_A are remaped into 2 insns. */
case BPF_RET | BPF_A:
case BPF_RET | BPF_K:
insn->code = BPF_ALU | BPF_MOV |
(BPF_RVAL(fp->code) == BPF_K ?
BPF_K : BPF_X);
insn->a_reg = 0;
insn->x_reg = A_REG;
insn->imm = fp->k;
insn++;
insn->code = BPF_JMP | BPF_EXIT;
break;
/* Store to stack. */
case BPF_ST:
case BPF_STX:
insn->code = BPF_STX | BPF_MEM | BPF_W;
insn->a_reg = FP_REG;
insn->x_reg = fp->code == BPF_ST ? A_REG : X_REG;
insn->off = -(BPF_MEMWORDS - fp->k) * 4;
break;
/* Load from stack. */
case BPF_LD | BPF_MEM:
case BPF_LDX | BPF_MEM:
insn->code = BPF_LDX | BPF_MEM | BPF_W;
insn->a_reg = BPF_CLASS(fp->code) == BPF_LD ?
A_REG : X_REG;
insn->x_reg = FP_REG;
insn->off = -(BPF_MEMWORDS - fp->k) * 4;
break;
/* A = K or X = K */
case BPF_LD | BPF_IMM:
case BPF_LDX | BPF_IMM:
insn->code = BPF_ALU | BPF_MOV | BPF_K;
insn->a_reg = BPF_CLASS(fp->code) == BPF_LD ?
A_REG : X_REG;
insn->imm = fp->k;
break;
/* X = A */
case BPF_MISC | BPF_TAX:
insn->code = BPF_ALU64 | BPF_MOV | BPF_X;
insn->a_reg = X_REG;
insn->x_reg = A_REG;
break;
/* A = X */
case BPF_MISC | BPF_TXA:
insn->code = BPF_ALU64 | BPF_MOV | BPF_X;
insn->a_reg = A_REG;
insn->x_reg = X_REG;
break;
/* A = skb->len or X = skb->len */
case BPF_LD | BPF_W | BPF_LEN:
case BPF_LDX | BPF_W | BPF_LEN:
insn->code = BPF_LDX | BPF_MEM | BPF_W;
insn->a_reg = BPF_CLASS(fp->code) == BPF_LD ?
A_REG : X_REG;
insn->x_reg = CTX_REG;
insn->off = offsetof(struct sk_buff, len);
break;
/* access seccomp_data fields */
case BPF_LDX | BPF_ABS | BPF_W:
insn->code = BPF_LDX | BPF_MEM | BPF_W;
insn->a_reg = A_REG;
insn->x_reg = CTX_REG;
insn->off = fp->k;
break;
default:
goto err;
}
insn++;
if (new_prog)
memcpy(new_insn, tmp_insns,
sizeof(*insn) * (insn - tmp_insns));
new_insn += insn - tmp_insns;
}
if (!new_prog) {
/* Only calculating new length. */
*new_len = new_insn - new_prog;
return 0;
}
pass++;
if (new_flen != new_insn - new_prog) {
new_flen = new_insn - new_prog;
if (pass > 2)
goto err;
goto do_pass;
}
kfree(addrs);
BUG_ON(*new_len != new_flen);
return 0;
err:
kfree(addrs);
return -EINVAL;
}
/* Security:
*
* A BPF program is able to use 16 cells of memory to store intermediate
* values (check u32 mem[BPF_MEMWORDS] in sk_run_filter()).
*
* As we dont want to clear mem[] array for each packet going through
* sk_run_filter(), we check that filter loaded by user never try to read
* a cell if not previously written, and we check all branches to be sure
* a malicious user doesn't try to abuse us.
*/
static int check_load_and_stores(struct sock_filter *filter, int flen)
{
u16 *masks, memvalid = 0; /* one bit per cell, 16 cells */
int pc, ret = 0;
BUILD_BUG_ON(BPF_MEMWORDS > 16);
masks = kmalloc(flen * sizeof(*masks), GFP_KERNEL);
if (!masks)
return -ENOMEM;
memset(masks, 0xff, flen * sizeof(*masks));
for (pc = 0; pc < flen; pc++) {
memvalid &= masks[pc];
switch (filter[pc].code) {
case BPF_S_ST:
case BPF_S_STX:
memvalid |= (1 << filter[pc].k);
break;
case BPF_S_LD_MEM:
case BPF_S_LDX_MEM:
if (!(memvalid & (1 << filter[pc].k))) {
ret = -EINVAL;
goto error;
}
break;
case BPF_S_JMP_JA:
/* a jump must set masks on target */
masks[pc + 1 + filter[pc].k] &= memvalid;
memvalid = ~0;
break;
case BPF_S_JMP_JEQ_K:
case BPF_S_JMP_JEQ_X:
case BPF_S_JMP_JGE_K:
case BPF_S_JMP_JGE_X:
case BPF_S_JMP_JGT_K:
case BPF_S_JMP_JGT_X:
case BPF_S_JMP_JSET_X:
case BPF_S_JMP_JSET_K:
/* a jump must set masks on targets */
masks[pc + 1 + filter[pc].jt] &= memvalid;
masks[pc + 1 + filter[pc].jf] &= memvalid;
memvalid = ~0;
break;
}
}
error:
kfree(masks);
return ret;
}
/**
* sk_chk_filter - verify socket filter code
* @filter: filter to verify
* @flen: length of filter
*
* Check the user's filter code. If we let some ugly
* filter code slip through kaboom! The filter must contain
* no references or jumps that are out of range, no illegal
* instructions, and must end with a RET instruction.
*
* All jumps are forward as they are not signed.
*
* Returns 0 if the rule set is legal or -EINVAL if not.
*/
int sk_chk_filter(struct sock_filter *filter, unsigned int flen)
{
/*
* Valid instructions are initialized to non-0.
* Invalid instructions are initialized to 0.
*/
static const u8 codes[] = {
[BPF_ALU|BPF_ADD|BPF_K] = BPF_S_ALU_ADD_K,
[BPF_ALU|BPF_ADD|BPF_X] = BPF_S_ALU_ADD_X,
[BPF_ALU|BPF_SUB|BPF_K] = BPF_S_ALU_SUB_K,
[BPF_ALU|BPF_SUB|BPF_X] = BPF_S_ALU_SUB_X,
[BPF_ALU|BPF_MUL|BPF_K] = BPF_S_ALU_MUL_K,
[BPF_ALU|BPF_MUL|BPF_X] = BPF_S_ALU_MUL_X,
[BPF_ALU|BPF_DIV|BPF_X] = BPF_S_ALU_DIV_X,
[BPF_ALU|BPF_MOD|BPF_K] = BPF_S_ALU_MOD_K,
[BPF_ALU|BPF_MOD|BPF_X] = BPF_S_ALU_MOD_X,
[BPF_ALU|BPF_AND|BPF_K] = BPF_S_ALU_AND_K,
[BPF_ALU|BPF_AND|BPF_X] = BPF_S_ALU_AND_X,
[BPF_ALU|BPF_OR|BPF_K] = BPF_S_ALU_OR_K,
[BPF_ALU|BPF_OR|BPF_X] = BPF_S_ALU_OR_X,
[BPF_ALU|BPF_XOR|BPF_K] = BPF_S_ALU_XOR_K,
[BPF_ALU|BPF_XOR|BPF_X] = BPF_S_ALU_XOR_X,
[BPF_ALU|BPF_LSH|BPF_K] = BPF_S_ALU_LSH_K,
[BPF_ALU|BPF_LSH|BPF_X] = BPF_S_ALU_LSH_X,
[BPF_ALU|BPF_RSH|BPF_K] = BPF_S_ALU_RSH_K,
[BPF_ALU|BPF_RSH|BPF_X] = BPF_S_ALU_RSH_X,
[BPF_ALU|BPF_NEG] = BPF_S_ALU_NEG,
[BPF_LD|BPF_W|BPF_ABS] = BPF_S_LD_W_ABS,
[BPF_LD|BPF_H|BPF_ABS] = BPF_S_LD_H_ABS,
[BPF_LD|BPF_B|BPF_ABS] = BPF_S_LD_B_ABS,
[BPF_LD|BPF_W|BPF_LEN] = BPF_S_LD_W_LEN,
[BPF_LD|BPF_W|BPF_IND] = BPF_S_LD_W_IND,
[BPF_LD|BPF_H|BPF_IND] = BPF_S_LD_H_IND,
[BPF_LD|BPF_B|BPF_IND] = BPF_S_LD_B_IND,
[BPF_LD|BPF_IMM] = BPF_S_LD_IMM,
[BPF_LDX|BPF_W|BPF_LEN] = BPF_S_LDX_W_LEN,
[BPF_LDX|BPF_B|BPF_MSH] = BPF_S_LDX_B_MSH,
[BPF_LDX|BPF_IMM] = BPF_S_LDX_IMM,
[BPF_MISC|BPF_TAX] = BPF_S_MISC_TAX,
[BPF_MISC|BPF_TXA] = BPF_S_MISC_TXA,
[BPF_RET|BPF_K] = BPF_S_RET_K,
[BPF_RET|BPF_A] = BPF_S_RET_A,
[BPF_ALU|BPF_DIV|BPF_K] = BPF_S_ALU_DIV_K,
[BPF_LD|BPF_MEM] = BPF_S_LD_MEM,
[BPF_LDX|BPF_MEM] = BPF_S_LDX_MEM,
[BPF_ST] = BPF_S_ST,
[BPF_STX] = BPF_S_STX,
[BPF_JMP|BPF_JA] = BPF_S_JMP_JA,
[BPF_JMP|BPF_JEQ|BPF_K] = BPF_S_JMP_JEQ_K,
[BPF_JMP|BPF_JEQ|BPF_X] = BPF_S_JMP_JEQ_X,
[BPF_JMP|BPF_JGE|BPF_K] = BPF_S_JMP_JGE_K,
[BPF_JMP|BPF_JGE|BPF_X] = BPF_S_JMP_JGE_X,
[BPF_JMP|BPF_JGT|BPF_K] = BPF_S_JMP_JGT_K,
[BPF_JMP|BPF_JGT|BPF_X] = BPF_S_JMP_JGT_X,
[BPF_JMP|BPF_JSET|BPF_K] = BPF_S_JMP_JSET_K,
[BPF_JMP|BPF_JSET|BPF_X] = BPF_S_JMP_JSET_X,
};
int pc;
bool anc_found;
if (flen == 0 || flen > BPF_MAXINSNS)
return -EINVAL;
/* check the filter code now */
for (pc = 0; pc < flen; pc++) {
struct sock_filter *ftest = &filter[pc];
u16 code = ftest->code;
if (code >= ARRAY_SIZE(codes))
return -EINVAL;
code = codes[code];
if (!code)
return -EINVAL;
/* Some instructions need special checks */
switch (code) {
case BPF_S_ALU_DIV_K:
case BPF_S_ALU_MOD_K:
/* check for division by zero */
if (ftest->k == 0)
return -EINVAL;
break;
case BPF_S_LD_MEM:
case BPF_S_LDX_MEM:
case BPF_S_ST:
case BPF_S_STX:
/* check for invalid memory addresses */
if (ftest->k >= BPF_MEMWORDS)
return -EINVAL;
break;
case BPF_S_JMP_JA:
/*
* Note, the large ftest->k might cause loops.
* Compare this with conditional jumps below,
* where offsets are limited. --ANK (981016)
*/
if (ftest->k >= (unsigned int)(flen-pc-1))
return -EINVAL;
break;
case BPF_S_JMP_JEQ_K:
case BPF_S_JMP_JEQ_X:
case BPF_S_JMP_JGE_K:
case BPF_S_JMP_JGE_X:
case BPF_S_JMP_JGT_K:
case BPF_S_JMP_JGT_X:
case BPF_S_JMP_JSET_X:
case BPF_S_JMP_JSET_K:
/* for conditionals both must be safe */
if (pc + ftest->jt + 1 >= flen ||
pc + ftest->jf + 1 >= flen)
return -EINVAL;
break;
case BPF_S_LD_W_ABS:
case BPF_S_LD_H_ABS:
case BPF_S_LD_B_ABS:
anc_found = false;
#define ANCILLARY(CODE) case SKF_AD_OFF + SKF_AD_##CODE: \
code = BPF_S_ANC_##CODE; \
anc_found = true; \
break
switch (ftest->k) {
ANCILLARY(PROTOCOL);
ANCILLARY(PKTTYPE);
ANCILLARY(IFINDEX);
ANCILLARY(NLATTR);
ANCILLARY(NLATTR_NEST);
ANCILLARY(MARK);
ANCILLARY(QUEUE);
ANCILLARY(HATYPE);
ANCILLARY(RXHASH);
ANCILLARY(CPU);
ANCILLARY(ALU_XOR_X);
ANCILLARY(VLAN_TAG);
ANCILLARY(VLAN_TAG_PRESENT);
ANCILLARY(PAY_OFFSET);
}
/* ancillary operation unknown or unsupported */
if (anc_found == false && ftest->k >= SKF_AD_OFF)
return -EINVAL;
}
ftest->code = code;
}
/* last instruction must be a RET code */
switch (filter[flen - 1].code) {
case BPF_S_RET_K:
case BPF_S_RET_A:
return check_load_and_stores(filter, flen);
}
return -EINVAL;
}
EXPORT_SYMBOL(sk_chk_filter);
static int sk_store_orig_filter(struct sk_filter *fp,
const struct sock_fprog *fprog)
{
unsigned int fsize = sk_filter_proglen(fprog);
struct sock_fprog_kern *fkprog;
fp->orig_prog = kmalloc(sizeof(*fkprog), GFP_KERNEL);
if (!fp->orig_prog)
return -ENOMEM;
fkprog = fp->orig_prog;
fkprog->len = fprog->len;
fkprog->filter = kmemdup(fp->insns, fsize, GFP_KERNEL);
if (!fkprog->filter) {
kfree(fp->orig_prog);
return -ENOMEM;
}
return 0;
}
static void sk_release_orig_filter(struct sk_filter *fp)
{
struct sock_fprog_kern *fprog = fp->orig_prog;
if (fprog) {
kfree(fprog->filter);
kfree(fprog);
}
}
/**
* sk_filter_release_rcu - Release a socket filter by rcu_head
* @rcu: rcu_head that contains the sk_filter to free
*/
static void sk_filter_release_rcu(struct rcu_head *rcu)
{
struct sk_filter *fp = container_of(rcu, struct sk_filter, rcu);
sk_release_orig_filter(fp);
bpf_jit_free(fp);
}
/**
* sk_filter_release - release a socket filter
* @fp: filter to remove
*
* Remove a filter from a socket and release its resources.
*/
static void sk_filter_release(struct sk_filter *fp)
{
if (atomic_dec_and_test(&fp->refcnt))
call_rcu(&fp->rcu, sk_filter_release_rcu);
}
void sk_filter_uncharge(struct sock *sk, struct sk_filter *fp)
{
atomic_sub(sk_filter_size(fp->len), &sk->sk_omem_alloc);
sk_filter_release(fp);
}
void sk_filter_charge(struct sock *sk, struct sk_filter *fp)
{
atomic_inc(&fp->refcnt);
atomic_add(sk_filter_size(fp->len), &sk->sk_omem_alloc);
}
static struct sk_filter *__sk_migrate_realloc(struct sk_filter *fp,
struct sock *sk,
unsigned int len)
{
struct sk_filter *fp_new;
if (sk == NULL)
return krealloc(fp, len, GFP_KERNEL);
fp_new = sock_kmalloc(sk, len, GFP_KERNEL);
if (fp_new) {
memcpy(fp_new, fp, sizeof(struct sk_filter));
/* As we're kepping orig_prog in fp_new along,
* we need to make sure we're not evicting it
* from the old fp.
*/
fp->orig_prog = NULL;
sk_filter_uncharge(sk, fp);
}
return fp_new;
}
static struct sk_filter *__sk_migrate_filter(struct sk_filter *fp,
struct sock *sk)
{
struct sock_filter *old_prog;
struct sk_filter *old_fp;
int i, err, new_len, old_len = fp->len;
/* We are free to overwrite insns et al right here as it
* won't be used at this point in time anymore internally
* after the migration to the internal BPF instruction
* representation.
*/
BUILD_BUG_ON(sizeof(struct sock_filter) !=
sizeof(struct sock_filter_int));
/* For now, we need to unfiddle BPF_S_* identifiers in place.
* This can sooner or later on be subject to removal, e.g. when
* JITs have been converted.
*/
for (i = 0; i < fp->len; i++)
sk_decode_filter(&fp->insns[i], &fp->insns[i]);
/* Conversion cannot happen on overlapping memory areas,
* so we need to keep the user BPF around until the 2nd
* pass. At this time, the user BPF is stored in fp->insns.
*/
old_prog = kmemdup(fp->insns, old_len * sizeof(struct sock_filter),
GFP_KERNEL);
if (!old_prog) {
err = -ENOMEM;
goto out_err;
}
/* 1st pass: calculate the new program length. */
err = sk_convert_filter(old_prog, old_len, NULL, &new_len);
if (err)
goto out_err_free;
/* Expand fp for appending the new filter representation. */
old_fp = fp;
fp = __sk_migrate_realloc(old_fp, sk, sk_filter_size(new_len));
if (!fp) {
/* The old_fp is still around in case we couldn't
* allocate new memory, so uncharge on that one.
*/
fp = old_fp;
err = -ENOMEM;
goto out_err_free;
}
fp->bpf_func = sk_run_filter_int_skb;
fp->len = new_len;
/* 2nd pass: remap sock_filter insns into sock_filter_int insns. */
err = sk_convert_filter(old_prog, old_len, fp->insnsi, &new_len);
if (err)
/* 2nd sk_convert_filter() can fail only if it fails
* to allocate memory, remapping must succeed. Note,
* that at this time old_fp has already been released
* by __sk_migrate_realloc().
*/
goto out_err_free;
kfree(old_prog);
return fp;
out_err_free:
kfree(old_prog);
out_err:
/* Rollback filter setup. */
if (sk != NULL)
sk_filter_uncharge(sk, fp);
else
kfree(fp);
return ERR_PTR(err);
}
static struct sk_filter *__sk_prepare_filter(struct sk_filter *fp,
struct sock *sk)
{
int err;
fp->bpf_func = NULL;
fp->jited = 0;
err = sk_chk_filter(fp->insns, fp->len);
if (err)
return ERR_PTR(err);
/* Probe if we can JIT compile the filter and if so, do
* the compilation of the filter.
*/
bpf_jit_compile(fp);
/* JIT compiler couldn't process this filter, so do the
* internal BPF translation for the optimized interpreter.
*/
if (!fp->jited)
fp = __sk_migrate_filter(fp, sk);
return fp;
}
/**
* sk_unattached_filter_create - create an unattached filter
* @fprog: the filter program
* @pfp: the unattached filter that is created
*
* Create a filter independent of any socket. We first run some
* sanity checks on it to make sure it does not explode on us later.
* If an error occurs or there is insufficient memory for the filter
* a negative errno code is returned. On success the return is zero.
*/
int sk_unattached_filter_create(struct sk_filter **pfp,
struct sock_fprog *fprog)
{
unsigned int fsize = sk_filter_proglen(fprog);
struct sk_filter *fp;
/* Make sure new filter is there and in the right amounts. */
if (fprog->filter == NULL)
return -EINVAL;
fp = kmalloc(sk_filter_size(fprog->len), GFP_KERNEL);
if (!fp)
return -ENOMEM;
memcpy(fp->insns, fprog->filter, fsize);
atomic_set(&fp->refcnt, 1);
fp->len = fprog->len;
/* Since unattached filters are not copied back to user
* space through sk_get_filter(), we do not need to hold
* a copy here, and can spare us the work.
*/
fp->orig_prog = NULL;
/* __sk_prepare_filter() already takes care of uncharging
* memory in case something goes wrong.
*/
fp = __sk_prepare_filter(fp, NULL);
if (IS_ERR(fp))
return PTR_ERR(fp);
*pfp = fp;
return 0;
}
EXPORT_SYMBOL_GPL(sk_unattached_filter_create);
void sk_unattached_filter_destroy(struct sk_filter *fp)
{
sk_filter_release(fp);
}
EXPORT_SYMBOL_GPL(sk_unattached_filter_destroy);
/**
* sk_attach_filter - attach a socket filter
* @fprog: the filter program
* @sk: the socket to use
*
* Attach the user's filter code. We first run some sanity checks on
* it to make sure it does not explode on us later. If an error
* occurs or there is insufficient memory for the filter a negative
* errno code is returned. On success the return is zero.
*/
int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk)
{
struct sk_filter *fp, *old_fp;
unsigned int fsize = sk_filter_proglen(fprog);
unsigned int sk_fsize = sk_filter_size(fprog->len);
int err;
if (sock_flag(sk, SOCK_FILTER_LOCKED))
return -EPERM;
/* Make sure new filter is there and in the right amounts. */
if (fprog->filter == NULL)
return -EINVAL;
fp = sock_kmalloc(sk, sk_fsize, GFP_KERNEL);
if (!fp)
return -ENOMEM;
if (copy_from_user(fp->insns, fprog->filter, fsize)) {
sock_kfree_s(sk, fp, sk_fsize);
return -EFAULT;
}
atomic_set(&fp->refcnt, 1);
fp->len = fprog->len;
err = sk_store_orig_filter(fp, fprog);
if (err) {
sk_filter_uncharge(sk, fp);
return -ENOMEM;
}
/* __sk_prepare_filter() already takes care of uncharging
* memory in case something goes wrong.
*/
fp = __sk_prepare_filter(fp, sk);
if (IS_ERR(fp))
return PTR_ERR(fp);
old_fp = rcu_dereference_protected(sk->sk_filter,
sock_owned_by_user(sk));
rcu_assign_pointer(sk->sk_filter, fp);
if (old_fp)
sk_filter_uncharge(sk, old_fp);
return 0;
}
EXPORT_SYMBOL_GPL(sk_attach_filter);
int sk_detach_filter(struct sock *sk)
{
int ret = -ENOENT;
struct sk_filter *filter;
if (sock_flag(sk, SOCK_FILTER_LOCKED))
return -EPERM;
filter = rcu_dereference_protected(sk->sk_filter,
sock_owned_by_user(sk));
if (filter) {
RCU_INIT_POINTER(sk->sk_filter, NULL);
sk_filter_uncharge(sk, filter);
ret = 0;
}
return ret;
}
EXPORT_SYMBOL_GPL(sk_detach_filter);
void sk_decode_filter(struct sock_filter *filt, struct sock_filter *to)
{
static const u16 decodes[] = {
[BPF_S_ALU_ADD_K] = BPF_ALU|BPF_ADD|BPF_K,
[BPF_S_ALU_ADD_X] = BPF_ALU|BPF_ADD|BPF_X,
[BPF_S_ALU_SUB_K] = BPF_ALU|BPF_SUB|BPF_K,
[BPF_S_ALU_SUB_X] = BPF_ALU|BPF_SUB|BPF_X,
[BPF_S_ALU_MUL_K] = BPF_ALU|BPF_MUL|BPF_K,
[BPF_S_ALU_MUL_X] = BPF_ALU|BPF_MUL|BPF_X,
[BPF_S_ALU_DIV_X] = BPF_ALU|BPF_DIV|BPF_X,
[BPF_S_ALU_MOD_K] = BPF_ALU|BPF_MOD|BPF_K,
[BPF_S_ALU_MOD_X] = BPF_ALU|BPF_MOD|BPF_X,
[BPF_S_ALU_AND_K] = BPF_ALU|BPF_AND|BPF_K,
[BPF_S_ALU_AND_X] = BPF_ALU|BPF_AND|BPF_X,
[BPF_S_ALU_OR_K] = BPF_ALU|BPF_OR|BPF_K,
[BPF_S_ALU_OR_X] = BPF_ALU|BPF_OR|BPF_X,
[BPF_S_ALU_XOR_K] = BPF_ALU|BPF_XOR|BPF_K,
[BPF_S_ALU_XOR_X] = BPF_ALU|BPF_XOR|BPF_X,
[BPF_S_ALU_LSH_K] = BPF_ALU|BPF_LSH|BPF_K,
[BPF_S_ALU_LSH_X] = BPF_ALU|BPF_LSH|BPF_X,
[BPF_S_ALU_RSH_K] = BPF_ALU|BPF_RSH|BPF_K,
[BPF_S_ALU_RSH_X] = BPF_ALU|BPF_RSH|BPF_X,
[BPF_S_ALU_NEG] = BPF_ALU|BPF_NEG,
[BPF_S_LD_W_ABS] = BPF_LD|BPF_W|BPF_ABS,
[BPF_S_LD_H_ABS] = BPF_LD|BPF_H|BPF_ABS,
[BPF_S_LD_B_ABS] = BPF_LD|BPF_B|BPF_ABS,
[BPF_S_ANC_PROTOCOL] = BPF_LD|BPF_B|BPF_ABS,
[BPF_S_ANC_PKTTYPE] = BPF_LD|BPF_B|BPF_ABS,
[BPF_S_ANC_IFINDEX] = BPF_LD|BPF_B|BPF_ABS,
[BPF_S_ANC_NLATTR] = BPF_LD|BPF_B|BPF_ABS,
[BPF_S_ANC_NLATTR_NEST] = BPF_LD|BPF_B|BPF_ABS,
[BPF_S_ANC_MARK] = BPF_LD|BPF_B|BPF_ABS,
[BPF_S_ANC_QUEUE] = BPF_LD|BPF_B|BPF_ABS,
[BPF_S_ANC_HATYPE] = BPF_LD|BPF_B|BPF_ABS,
[BPF_S_ANC_RXHASH] = BPF_LD|BPF_B|BPF_ABS,
[BPF_S_ANC_CPU] = BPF_LD|BPF_B|BPF_ABS,
[BPF_S_ANC_ALU_XOR_X] = BPF_LD|BPF_B|BPF_ABS,
[BPF_S_ANC_VLAN_TAG] = BPF_LD|BPF_B|BPF_ABS,
[BPF_S_ANC_VLAN_TAG_PRESENT] = BPF_LD|BPF_B|BPF_ABS,
[BPF_S_ANC_PAY_OFFSET] = BPF_LD|BPF_B|BPF_ABS,
[BPF_S_LD_W_LEN] = BPF_LD|BPF_W|BPF_LEN,
[BPF_S_LD_W_IND] = BPF_LD|BPF_W|BPF_IND,
[BPF_S_LD_H_IND] = BPF_LD|BPF_H|BPF_IND,
[BPF_S_LD_B_IND] = BPF_LD|BPF_B|BPF_IND,
[BPF_S_LD_IMM] = BPF_LD|BPF_IMM,
[BPF_S_LDX_W_LEN] = BPF_LDX|BPF_W|BPF_LEN,
[BPF_S_LDX_B_MSH] = BPF_LDX|BPF_B|BPF_MSH,
[BPF_S_LDX_IMM] = BPF_LDX|BPF_IMM,
[BPF_S_MISC_TAX] = BPF_MISC|BPF_TAX,
[BPF_S_MISC_TXA] = BPF_MISC|BPF_TXA,
[BPF_S_RET_K] = BPF_RET|BPF_K,
[BPF_S_RET_A] = BPF_RET|BPF_A,
[BPF_S_ALU_DIV_K] = BPF_ALU|BPF_DIV|BPF_K,
[BPF_S_LD_MEM] = BPF_LD|BPF_MEM,
[BPF_S_LDX_MEM] = BPF_LDX|BPF_MEM,
[BPF_S_ST] = BPF_ST,
[BPF_S_STX] = BPF_STX,
[BPF_S_JMP_JA] = BPF_JMP|BPF_JA,
[BPF_S_JMP_JEQ_K] = BPF_JMP|BPF_JEQ|BPF_K,
[BPF_S_JMP_JEQ_X] = BPF_JMP|BPF_JEQ|BPF_X,
[BPF_S_JMP_JGE_K] = BPF_JMP|BPF_JGE|BPF_K,
[BPF_S_JMP_JGE_X] = BPF_JMP|BPF_JGE|BPF_X,
[BPF_S_JMP_JGT_K] = BPF_JMP|BPF_JGT|BPF_K,
[BPF_S_JMP_JGT_X] = BPF_JMP|BPF_JGT|BPF_X,
[BPF_S_JMP_JSET_K] = BPF_JMP|BPF_JSET|BPF_K,
[BPF_S_JMP_JSET_X] = BPF_JMP|BPF_JSET|BPF_X,
};
u16 code;
code = filt->code;
to->code = decodes[code];
to->jt = filt->jt;
to->jf = filt->jf;
to->k = filt->k;
}
int sk_get_filter(struct sock *sk, struct sock_filter __user *ubuf,
unsigned int len)
{
struct sock_fprog_kern *fprog;
struct sk_filter *filter;
int ret = 0;
lock_sock(sk);
filter = rcu_dereference_protected(sk->sk_filter,
sock_owned_by_user(sk));
if (!filter)
goto out;
/* We're copying the filter that has been originally attached,
* so no conversion/decode needed anymore.
*/
fprog = filter->orig_prog;
ret = fprog->len;
if (!len)
/* User space only enquires number of filter blocks. */
goto out;
ret = -EINVAL;
if (len < fprog->len)
goto out;
ret = -EFAULT;
if (copy_to_user(ubuf, fprog->filter, sk_filter_proglen(fprog)))
goto out;
/* Instead of bytes, the API requests to return the number
* of filter blocks.
*/
ret = fprog->len;
out:
release_sock(sk);
return ret;
}
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