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| author | David S. Miller <davem@davemloft.net> | 2016-05-20 19:53:09 -0400 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2016-05-20 19:53:09 -0400 |
| commit | cb543e80f43b2db9d3adcc80d522b27829e60d82 (patch) | |
| tree | 1f5773cda4c0b535c4432f12a633ff304d11a004 | |
| parent | 238a9584e9e2c7b3ea23924e9183fee05d584789 (diff) | |
| parent | 1b9b69ecb3a5236d4d3da0f0fa11af916371841e (diff) | |
| download | linux-cb543e80f43b2db9d3adcc80d522b27829e60d82.tar.bz2 | |
Merge branch 'bpf-verifier-fixes'
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>
| -rw-r--r-- | kernel/bpf/verifier.c | 30 |
1 files changed, 21 insertions, 9 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index a08d66215245..668e07903c8f 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -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 = ®s[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 = ®s[insn->dst_reg]; struct reg_state *src_reg = ®s[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 && |