![Alexei Starovoitov](/assets/img/avatar_default.png)
Introduce BPF helper macros to define instructions (similar to old BPF_STMT/BPF_JUMP macros) Use them while converting classic BPF to internal and in BPF testsuite later. Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
1799 lines
44 KiB
C
1799 lines
44 KiB
C
/*
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* Linux Socket Filter - Kernel level socket filtering
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*
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* Based on the design of the Berkeley Packet Filter. The new
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* internal format has been designed by PLUMgrid:
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*
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* Copyright (c) 2011 - 2014 PLUMgrid, http://plumgrid.com
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*
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* Authors:
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*
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* Jay Schulist <jschlst@samba.org>
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* Alexei Starovoitov <ast@plumgrid.com>
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* Daniel Borkmann <dborkman@redhat.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 the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* Andi Kleen - Fix a few bad bugs and races.
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* Kris Katterjohn - Added many additional checks in sk_chk_filter()
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*/
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#include <linux/module.h>
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#include <linux/types.h>
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#include <linux/mm.h>
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#include <linux/fcntl.h>
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#include <linux/socket.h>
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#include <linux/in.h>
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#include <linux/inet.h>
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#include <linux/netdevice.h>
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#include <linux/if_packet.h>
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#include <linux/gfp.h>
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#include <net/ip.h>
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#include <net/protocol.h>
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#include <net/netlink.h>
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#include <linux/skbuff.h>
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#include <net/sock.h>
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#include <linux/errno.h>
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#include <linux/timer.h>
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#include <asm/uaccess.h>
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#include <asm/unaligned.h>
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#include <linux/filter.h>
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#include <linux/ratelimit.h>
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#include <linux/seccomp.h>
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#include <linux/if_vlan.h>
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/* Registers */
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#define R0 regs[BPF_REG_0]
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#define R1 regs[BPF_REG_1]
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#define R2 regs[BPF_REG_2]
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#define R3 regs[BPF_REG_3]
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#define R4 regs[BPF_REG_4]
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#define R5 regs[BPF_REG_5]
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#define R6 regs[BPF_REG_6]
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#define R7 regs[BPF_REG_7]
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#define R8 regs[BPF_REG_8]
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#define R9 regs[BPF_REG_9]
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#define R10 regs[BPF_REG_10]
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/* Named registers */
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#define A regs[insn->a_reg]
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#define X regs[insn->x_reg]
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#define FP regs[BPF_REG_FP]
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#define ARG1 regs[BPF_REG_ARG1]
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#define CTX regs[BPF_REG_CTX]
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#define K insn->imm
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/* No hurry in this branch
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*
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* Exported for the bpf jit load helper.
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*/
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void *bpf_internal_load_pointer_neg_helper(const struct sk_buff *skb, int k, unsigned int size)
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{
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u8 *ptr = NULL;
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if (k >= SKF_NET_OFF)
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ptr = skb_network_header(skb) + k - SKF_NET_OFF;
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else if (k >= SKF_LL_OFF)
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ptr = skb_mac_header(skb) + k - SKF_LL_OFF;
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if (ptr >= skb->head && ptr + size <= skb_tail_pointer(skb))
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return ptr;
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return NULL;
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}
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static inline void *load_pointer(const struct sk_buff *skb, int k,
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unsigned int size, void *buffer)
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{
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if (k >= 0)
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return skb_header_pointer(skb, k, size, buffer);
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return bpf_internal_load_pointer_neg_helper(skb, k, size);
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}
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/**
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* sk_filter - run a packet through a socket filter
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* @sk: sock associated with &sk_buff
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* @skb: buffer to filter
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*
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* Run the filter code and then cut skb->data to correct size returned by
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* sk_run_filter. If pkt_len is 0 we toss packet. If skb->len is smaller
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* than pkt_len we keep whole skb->data. This is the socket level
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* wrapper to sk_run_filter. It returns 0 if the packet should
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* be accepted or -EPERM if the packet should be tossed.
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*
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*/
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int sk_filter(struct sock *sk, struct sk_buff *skb)
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{
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int err;
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struct sk_filter *filter;
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/*
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* If the skb was allocated from pfmemalloc reserves, only
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* allow SOCK_MEMALLOC sockets to use it as this socket is
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* helping free memory
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*/
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if (skb_pfmemalloc(skb) && !sock_flag(sk, SOCK_MEMALLOC))
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return -ENOMEM;
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err = security_sock_rcv_skb(sk, skb);
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if (err)
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return err;
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rcu_read_lock();
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filter = rcu_dereference(sk->sk_filter);
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if (filter) {
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unsigned int pkt_len = SK_RUN_FILTER(filter, skb);
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err = pkt_len ? pskb_trim(skb, pkt_len) : -EPERM;
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}
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rcu_read_unlock();
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return err;
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}
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EXPORT_SYMBOL(sk_filter);
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/* Base function for offset calculation. Needs to go into .text section,
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* therefore keeping it non-static as well; will also be used by JITs
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* anyway later on, so do not let the compiler omit it.
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*/
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noinline u64 __bpf_call_base(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
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{
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return 0;
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}
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/**
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* __sk_run_filter - run a filter on a given context
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* @ctx: buffer to run the filter on
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* @insn: filter to apply
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*
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* Decode and apply filter instructions to the skb->data. Return length to
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* keep, 0 for none. @ctx is the data we are operating on, @insn is the
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* array of filter instructions.
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*/
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unsigned int __sk_run_filter(void *ctx, const struct sock_filter_int *insn)
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{
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u64 stack[MAX_BPF_STACK / sizeof(u64)];
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u64 regs[MAX_BPF_REG], tmp;
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static const void *jumptable[256] = {
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[0 ... 255] = &&default_label,
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/* Now overwrite non-defaults ... */
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#define DL(A, B, C) [BPF_##A|BPF_##B|BPF_##C] = &&A##_##B##_##C
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DL(ALU, ADD, X),
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DL(ALU, ADD, K),
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DL(ALU, SUB, X),
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DL(ALU, SUB, K),
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DL(ALU, AND, X),
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DL(ALU, AND, K),
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DL(ALU, OR, X),
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DL(ALU, OR, K),
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DL(ALU, LSH, X),
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DL(ALU, LSH, K),
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DL(ALU, RSH, X),
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DL(ALU, RSH, K),
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DL(ALU, XOR, X),
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DL(ALU, XOR, K),
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DL(ALU, MUL, X),
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DL(ALU, MUL, K),
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DL(ALU, MOV, X),
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DL(ALU, MOV, K),
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DL(ALU, DIV, X),
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DL(ALU, DIV, K),
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DL(ALU, MOD, X),
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DL(ALU, MOD, K),
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DL(ALU, NEG, 0),
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DL(ALU, END, TO_BE),
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DL(ALU, END, TO_LE),
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DL(ALU64, ADD, X),
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DL(ALU64, ADD, K),
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DL(ALU64, SUB, X),
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DL(ALU64, SUB, K),
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DL(ALU64, AND, X),
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DL(ALU64, AND, K),
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DL(ALU64, OR, X),
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DL(ALU64, OR, K),
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DL(ALU64, LSH, X),
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DL(ALU64, LSH, K),
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DL(ALU64, RSH, X),
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DL(ALU64, RSH, K),
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DL(ALU64, XOR, X),
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DL(ALU64, XOR, K),
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DL(ALU64, MUL, X),
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DL(ALU64, MUL, K),
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DL(ALU64, MOV, X),
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DL(ALU64, MOV, K),
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DL(ALU64, ARSH, X),
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DL(ALU64, ARSH, K),
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DL(ALU64, DIV, X),
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DL(ALU64, DIV, K),
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DL(ALU64, MOD, X),
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DL(ALU64, MOD, K),
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DL(ALU64, NEG, 0),
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DL(JMP, CALL, 0),
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DL(JMP, JA, 0),
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DL(JMP, JEQ, X),
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DL(JMP, JEQ, K),
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DL(JMP, JNE, X),
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DL(JMP, JNE, K),
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DL(JMP, JGT, X),
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DL(JMP, JGT, K),
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DL(JMP, JGE, X),
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DL(JMP, JGE, K),
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DL(JMP, JSGT, X),
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DL(JMP, JSGT, K),
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DL(JMP, JSGE, X),
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DL(JMP, JSGE, K),
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DL(JMP, JSET, X),
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DL(JMP, JSET, K),
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DL(JMP, EXIT, 0),
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DL(STX, MEM, B),
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DL(STX, MEM, H),
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DL(STX, MEM, W),
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DL(STX, MEM, DW),
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DL(STX, XADD, W),
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DL(STX, XADD, DW),
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DL(ST, MEM, B),
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DL(ST, MEM, H),
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DL(ST, MEM, W),
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DL(ST, MEM, DW),
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DL(LDX, MEM, B),
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DL(LDX, MEM, H),
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DL(LDX, MEM, W),
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DL(LDX, MEM, DW),
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DL(LD, ABS, W),
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DL(LD, ABS, H),
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DL(LD, ABS, B),
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DL(LD, IND, W),
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DL(LD, IND, H),
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DL(LD, IND, B),
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#undef DL
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};
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void *ptr;
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int off;
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#define CONT ({ insn++; goto select_insn; })
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#define CONT_JMP ({ insn++; goto select_insn; })
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FP = (u64) (unsigned long) &stack[ARRAY_SIZE(stack)];
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ARG1 = (u64) (unsigned long) ctx;
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/* Register for user BPF programs need to be reset first. */
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regs[BPF_REG_A] = 0;
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regs[BPF_REG_X] = 0;
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select_insn:
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goto *jumptable[insn->code];
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/* ALU */
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#define ALU(OPCODE, OP) \
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ALU64_##OPCODE##_X: \
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A = A OP X; \
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CONT; \
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ALU_##OPCODE##_X: \
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A = (u32) A OP (u32) X; \
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CONT; \
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ALU64_##OPCODE##_K: \
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A = A OP K; \
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CONT; \
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ALU_##OPCODE##_K: \
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A = (u32) A OP (u32) K; \
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CONT;
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ALU(ADD, +)
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ALU(SUB, -)
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ALU(AND, &)
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ALU(OR, |)
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ALU(LSH, <<)
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ALU(RSH, >>)
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ALU(XOR, ^)
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ALU(MUL, *)
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#undef ALU
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ALU_NEG_0:
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A = (u32) -A;
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CONT;
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ALU64_NEG_0:
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A = -A;
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CONT;
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ALU_MOV_X:
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A = (u32) X;
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CONT;
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ALU_MOV_K:
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A = (u32) K;
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CONT;
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ALU64_MOV_X:
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A = X;
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CONT;
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ALU64_MOV_K:
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A = K;
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CONT;
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ALU64_ARSH_X:
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(*(s64 *) &A) >>= X;
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CONT;
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ALU64_ARSH_K:
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(*(s64 *) &A) >>= K;
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CONT;
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ALU64_MOD_X:
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if (unlikely(X == 0))
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return 0;
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tmp = A;
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A = do_div(tmp, X);
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CONT;
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ALU_MOD_X:
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if (unlikely(X == 0))
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return 0;
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tmp = (u32) A;
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A = do_div(tmp, (u32) X);
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CONT;
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ALU64_MOD_K:
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tmp = A;
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A = do_div(tmp, K);
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CONT;
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ALU_MOD_K:
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tmp = (u32) A;
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A = do_div(tmp, (u32) K);
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CONT;
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ALU64_DIV_X:
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if (unlikely(X == 0))
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return 0;
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do_div(A, X);
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CONT;
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ALU_DIV_X:
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if (unlikely(X == 0))
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return 0;
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tmp = (u32) A;
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do_div(tmp, (u32) X);
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A = (u32) tmp;
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CONT;
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ALU64_DIV_K:
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do_div(A, K);
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CONT;
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ALU_DIV_K:
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tmp = (u32) A;
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do_div(tmp, (u32) K);
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A = (u32) tmp;
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CONT;
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ALU_END_TO_BE:
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switch (K) {
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case 16:
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A = (__force u16) cpu_to_be16(A);
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break;
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case 32:
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A = (__force u32) cpu_to_be32(A);
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break;
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case 64:
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A = (__force u64) cpu_to_be64(A);
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break;
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}
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CONT;
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ALU_END_TO_LE:
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switch (K) {
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case 16:
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A = (__force u16) cpu_to_le16(A);
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break;
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case 32:
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A = (__force u32) cpu_to_le32(A);
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break;
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case 64:
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A = (__force u64) cpu_to_le64(A);
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break;
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}
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CONT;
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/* CALL */
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JMP_CALL_0:
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/* Function call scratches R1-R5 registers, preserves R6-R9,
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* and stores return value into R0.
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*/
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R0 = (__bpf_call_base + insn->imm)(R1, R2, R3, R4, R5);
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CONT;
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/* JMP */
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JMP_JA_0:
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insn += insn->off;
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CONT;
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JMP_JEQ_X:
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if (A == X) {
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insn += insn->off;
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CONT_JMP;
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}
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CONT;
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JMP_JEQ_K:
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if (A == K) {
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insn += insn->off;
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CONT_JMP;
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}
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CONT;
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JMP_JNE_X:
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if (A != X) {
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insn += insn->off;
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CONT_JMP;
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}
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CONT;
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JMP_JNE_K:
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if (A != K) {
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insn += insn->off;
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CONT_JMP;
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}
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CONT;
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JMP_JGT_X:
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if (A > X) {
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insn += insn->off;
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CONT_JMP;
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}
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CONT;
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JMP_JGT_K:
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if (A > K) {
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insn += insn->off;
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CONT_JMP;
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}
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CONT;
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JMP_JGE_X:
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if (A >= X) {
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insn += insn->off;
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CONT_JMP;
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}
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CONT;
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JMP_JGE_K:
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if (A >= K) {
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insn += insn->off;
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CONT_JMP;
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}
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CONT;
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JMP_JSGT_X:
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if (((s64) A) > ((s64) X)) {
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insn += insn->off;
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CONT_JMP;
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}
|
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CONT;
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JMP_JSGT_K:
|
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if (((s64) A) > ((s64) K)) {
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insn += insn->off;
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CONT_JMP;
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}
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CONT;
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JMP_JSGE_X:
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if (((s64) A) >= ((s64) X)) {
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insn += insn->off;
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CONT_JMP;
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}
|
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CONT;
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JMP_JSGE_K:
|
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if (((s64) A) >= ((s64) K)) {
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insn += insn->off;
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CONT_JMP;
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}
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CONT;
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JMP_JSET_X:
|
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if (A & X) {
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insn += insn->off;
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CONT_JMP;
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}
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CONT;
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JMP_JSET_K:
|
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if (A & K) {
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insn += insn->off;
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CONT_JMP;
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}
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CONT;
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|
JMP_EXIT_0:
|
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return R0;
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|
|
/* STX and ST and LDX*/
|
|
#define LDST(SIZEOP, SIZE) \
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STX_MEM_##SIZEOP: \
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*(SIZE *)(unsigned long) (A + insn->off) = X; \
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CONT; \
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ST_MEM_##SIZEOP: \
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*(SIZE *)(unsigned long) (A + insn->off) = K; \
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CONT; \
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LDX_MEM_##SIZEOP: \
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A = *(SIZE *)(unsigned long) (X + insn->off); \
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CONT;
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LDST(B, u8)
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LDST(H, u16)
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LDST(W, u32)
|
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LDST(DW, u64)
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#undef LDST
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STX_XADD_W: /* lock xadd *(u32 *)(A + insn->off) += X */
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atomic_add((u32) X, (atomic_t *)(unsigned long)
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(A + insn->off));
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CONT;
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STX_XADD_DW: /* lock xadd *(u64 *)(A + insn->off) += X */
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atomic64_add((u64) X, (atomic64_t *)(unsigned long)
|
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(A + insn->off));
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CONT;
|
|
LD_ABS_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[BPF_REG_CTX] == 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;
|
|
LD_ABS_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;
|
|
LD_ABS_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;
|
|
LD_IND_W: /* R0 = ntohl(*(u32 *) (skb->data + X + K)) */
|
|
off = K + X;
|
|
goto load_word;
|
|
LD_IND_H: /* R0 = ntohs(*(u16 *) (skb->data + X + K)) */
|
|
off = K + X;
|
|
goto load_half;
|
|
LD_IND_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;
|
|
}
|
|
|
|
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)
|
|
{
|
|
return __skb_get_poff((struct sk_buff *)(unsigned long) ctx);
|
|
}
|
|
|
|
static u64 __skb_get_nlattr(u64 ctx, u64 a, u64 x, u64 r4, u64 r5)
|
|
{
|
|
struct sk_buff *skb = (struct sk_buff *)(unsigned 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 *)(unsigned 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();
|
|
}
|
|
|
|
/* note that this only generates 32-bit random numbers */
|
|
static u64 __get_random_u32(u64 ctx, u64 a, u64 x, u64 r4, u64 r5)
|
|
{
|
|
return prandom_u32();
|
|
}
|
|
|
|
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);
|
|
|
|
/* A = *(u16 *) (ctx + offsetof(protocol)) */
|
|
*insn = BPF_LDX_MEM(BPF_H, BPF_REG_A, BPF_REG_CTX,
|
|
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 = BPF_REG_A;
|
|
insn->imm = 16;
|
|
break;
|
|
|
|
case SKF_AD_OFF + SKF_AD_PKTTYPE:
|
|
*insn = BPF_LDX_MEM(BPF_B, BPF_REG_A, BPF_REG_CTX,
|
|
pkt_type_offset());
|
|
if (insn->off < 0)
|
|
return false;
|
|
insn++;
|
|
|
|
*insn = BPF_ALU32_IMM(BPF_AND, BPF_REG_A, PKT_TYPE_MAX);
|
|
break;
|
|
|
|
case SKF_AD_OFF + SKF_AD_IFINDEX:
|
|
case SKF_AD_OFF + SKF_AD_HATYPE:
|
|
*insn = BPF_LDX_MEM(size_to_bpf(FIELD_SIZEOF(struct sk_buff, dev)),
|
|
BPF_REG_TMP, BPF_REG_CTX,
|
|
offsetof(struct sk_buff, dev));
|
|
insn++;
|
|
|
|
/* if (tmp != 0) goto pc+1 */
|
|
*insn = BPF_JMP_IMM(BPF_JNE, BPF_REG_TMP, 0, 1);
|
|
insn++;
|
|
|
|
*insn = BPF_EXIT_INSN();
|
|
insn++;
|
|
|
|
BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, ifindex) != 4);
|
|
BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, type) != 2);
|
|
|
|
insn->a_reg = BPF_REG_A;
|
|
insn->x_reg = BPF_REG_TMP;
|
|
|
|
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 = BPF_LDX_MEM(BPF_W, BPF_REG_A, BPF_REG_CTX,
|
|
offsetof(struct sk_buff, mark));
|
|
break;
|
|
|
|
case SKF_AD_OFF + SKF_AD_RXHASH:
|
|
BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, hash) != 4);
|
|
|
|
*insn = BPF_LDX_MEM(BPF_W, BPF_REG_A, BPF_REG_CTX,
|
|
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 = BPF_LDX_MEM(BPF_H, BPF_REG_A, BPF_REG_CTX,
|
|
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);
|
|
|
|
/* A = *(u16 *) (ctx + offsetof(vlan_tci)) */
|
|
*insn = BPF_LDX_MEM(BPF_H, BPF_REG_A, BPF_REG_CTX,
|
|
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 = BPF_ALU32_IMM(BPF_AND, BPF_REG_A,
|
|
~VLAN_TAG_PRESENT);
|
|
} else {
|
|
/* A >>= 12 */
|
|
*insn = BPF_ALU32_IMM(BPF_RSH, BPF_REG_A, 12);
|
|
insn++;
|
|
|
|
/* A &= 1 */
|
|
*insn = BPF_ALU32_IMM(BPF_AND, BPF_REG_A, 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:
|
|
case SKF_AD_OFF + SKF_AD_RANDOM:
|
|
/* arg1 = ctx */
|
|
*insn = BPF_ALU64_REG(BPF_MOV, BPF_REG_ARG1, BPF_REG_CTX);
|
|
insn++;
|
|
|
|
/* arg2 = A */
|
|
*insn = BPF_ALU64_REG(BPF_MOV, BPF_REG_ARG2, BPF_REG_A);
|
|
insn++;
|
|
|
|
/* arg3 = X */
|
|
*insn = BPF_ALU64_REG(BPF_MOV, BPF_REG_ARG3, BPF_REG_X);
|
|
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;
|
|
case SKF_AD_OFF + SKF_AD_RANDOM:
|
|
insn->imm = __get_random_u32 - __bpf_call_base;
|
|
break;
|
|
}
|
|
break;
|
|
|
|
case SKF_AD_OFF + SKF_AD_ALU_XOR_X:
|
|
/* A ^= X */
|
|
*insn = BPF_ALU32_REG(BPF_XOR, BPF_REG_A, BPF_REG_X);
|
|
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(BPF_REG_FP + 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 = BPF_ALU64_REG(BPF_MOV, BPF_REG_CTX, BPF_REG_ARG1);
|
|
}
|
|
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 = BPF_REG_A;
|
|
insn->x_reg = BPF_REG_X;
|
|
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 = BPF_REG_TMP;
|
|
insn->imm = fp->k;
|
|
insn++;
|
|
|
|
insn->a_reg = BPF_REG_A;
|
|
insn->x_reg = BPF_REG_TMP;
|
|
bpf_src = BPF_X;
|
|
} else {
|
|
insn->a_reg = BPF_REG_A;
|
|
insn->x_reg = BPF_REG_X;
|
|
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:
|
|
/* tmp = A */
|
|
*insn = BPF_ALU64_REG(BPF_MOV, BPF_REG_TMP, BPF_REG_A);
|
|
insn++;
|
|
|
|
/* A = R0 = *(u8 *) (skb->data + K) */
|
|
*insn = BPF_LD_ABS(BPF_B, fp->k);
|
|
insn++;
|
|
|
|
/* A &= 0xf */
|
|
*insn = BPF_ALU32_IMM(BPF_AND, BPF_REG_A, 0xf);
|
|
insn++;
|
|
|
|
/* A <<= 2 */
|
|
*insn = BPF_ALU32_IMM(BPF_LSH, BPF_REG_A, 2);
|
|
insn++;
|
|
|
|
/* X = A */
|
|
*insn = BPF_ALU64_REG(BPF_MOV, BPF_REG_X, BPF_REG_A);
|
|
insn++;
|
|
|
|
/* A = tmp */
|
|
*insn = BPF_ALU64_REG(BPF_MOV, BPF_REG_A, BPF_REG_TMP);
|
|
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 = BPF_REG_A;
|
|
insn->imm = fp->k;
|
|
insn++;
|
|
|
|
*insn = BPF_EXIT_INSN();
|
|
break;
|
|
|
|
/* Store to stack. */
|
|
case BPF_ST:
|
|
case BPF_STX:
|
|
insn->code = BPF_STX | BPF_MEM | BPF_W;
|
|
insn->a_reg = BPF_REG_FP;
|
|
insn->x_reg = fp->code == BPF_ST ?
|
|
BPF_REG_A : BPF_REG_X;
|
|
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 ?
|
|
BPF_REG_A : BPF_REG_X;
|
|
insn->x_reg = BPF_REG_FP;
|
|
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 ?
|
|
BPF_REG_A : BPF_REG_X;
|
|
insn->imm = fp->k;
|
|
break;
|
|
|
|
/* X = A */
|
|
case BPF_MISC | BPF_TAX:
|
|
*insn = BPF_ALU64_REG(BPF_MOV, BPF_REG_X, BPF_REG_A);
|
|
break;
|
|
|
|
/* A = X */
|
|
case BPF_MISC | BPF_TXA:
|
|
*insn = BPF_ALU64_REG(BPF_MOV, BPF_REG_A, BPF_REG_X);
|
|
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 ?
|
|
BPF_REG_A : BPF_REG_X;
|
|
insn->x_reg = BPF_REG_CTX;
|
|
insn->off = offsetof(struct sk_buff, len);
|
|
break;
|
|
|
|
/* access seccomp_data fields */
|
|
case BPF_LDX | BPF_ABS | BPF_W:
|
|
/* A = *(u32 *) (ctx + K) */
|
|
*insn = BPF_LDX_MEM(BPF_W, BPF_REG_A, BPF_REG_CTX, 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(RANDOM);
|
|
}
|
|
|
|
/* 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) {
|
|
*fp_new = *fp;
|
|
/* 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_ANC_RANDOM] = 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;
|
|
}
|