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Merge branch 'bpf-verifier-fixes'

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Alexei Starovoitov says:

====================
bpf: verifier fixes

Further testing of 'direct packet access' uncovered
several usability issues. Fix them.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller 2016-05-20 19:53:09 -04:00
commit cb543e80f4
1 changed files with 21 additions and 9 deletions
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30
kernel/bpf/verifier.c
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@ -683,15 +683,11 @@ static int check_packet_access(struct verifier_env *env, u32 regno, int off,
{
struct reg_state *regs = env->cur_state.regs;
struct reg_state *reg = &regs[regno];
int linear_size = (int) reg->range - (int) reg->off;
if (linear_size < 0 || linear_size >= MAX_PACKET_OFF) {
verbose("verifier bug\n");
return -EFAULT;
}
if (off < 0 || off + size > linear_size) {
verbose("invalid access to packet, off=%d size=%d, allowed=%d\n",
off, size, linear_size);
off += reg->off;
if (off < 0 || off + size > reg->range) {
verbose("invalid access to packet, off=%d size=%d, R%d(id=%d,off=%d,r=%d)\n",
off, size, regno, reg->id, reg->off, reg->range);
return -EACCES;
}
return 0;
@ -1249,6 +1245,7 @@ static int check_packet_ptr_add(struct verifier_env *env, struct bpf_insn *insn)
struct reg_state *regs = env->cur_state.regs;
struct reg_state *dst_reg = &regs[insn->dst_reg];
struct reg_state *src_reg = &regs[insn->src_reg];
struct reg_state tmp_reg;
s32 imm;
if (BPF_SRC(insn->code) == BPF_K) {
@ -1271,6 +1268,19 @@ add_imm:
*/
dst_reg->off += imm;
} else {
if (src_reg->type == PTR_TO_PACKET) {
/* R6=pkt(id=0,off=0,r=62) R7=imm22; r7 += r6 */
tmp_reg = *dst_reg; /* save r7 state */
*dst_reg = *src_reg; /* copy pkt_ptr state r6 into r7 */
src_reg = &tmp_reg; /* pretend it's src_reg state */
/* if the checks below reject it, the copy won't matter,
* since we're rejecting the whole program. If all ok,
* then imm22 state will be added to r7
* and r7 will be pkt(id=0,off=22,r=62) while
* r6 will stay as pkt(id=0,off=0,r=62)
*/
}
if (src_reg->type == CONST_IMM) {
/* pkt_ptr += reg where reg is known constant */
imm = src_reg->imm;
@ -1569,7 +1579,9 @@ static int check_alu_op(struct verifier_env *env, struct bpf_insn *insn)
return 0;
} else if (opcode == BPF_ADD &&
BPF_CLASS(insn->code) == BPF_ALU64 &&
dst_reg->type == PTR_TO_PACKET) {
(dst_reg->type == PTR_TO_PACKET ||
(BPF_SRC(insn->code) == BPF_X &&
regs[insn->src_reg].type == PTR_TO_PACKET))) {
/* ptr_to_packet += K|X */
return check_packet_ptr_add(env, insn);
} else if (BPF_CLASS(insn->code) == BPF_ALU64 &&