/*
* 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;
}
/* 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
/**
* __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;
regs[A_REG] = 0;
regs[X_REG] = 0;
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();
}
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;
}
