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Date: Wed, 1 Nov 2017 23:58:10 +0100
From: Daniel Borkmann <daniel@...earbox.net>
To: davem@...emloft.net
Cc: alexei.starovoitov@...il.com, john.r.fastabend@...il.com,
netdev@...r.kernel.org, Daniel Borkmann <daniel@...earbox.net>
Subject: [PATCH net-next 2/3] bpf: also improve pattern matches for meta access
Follow-up to 0fd4759c5515 ("bpf: fix pattern matches for direct
packet access") to cover also the remaining data_meta/data matches
in the verifier. The matches are also refactored a bit to simplify
handling of all the cases.
Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
Acked-by: Alexei Starovoitov <ast@...nel.org>
Acked-by: John Fastabend <john.fastabend@...il.com>
---
kernel/bpf/verifier.c | 165 +++++++++++++++++++++++++++++---------------------
1 file changed, 96 insertions(+), 69 deletions(-)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 2cc3e94..530b685 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -2787,6 +2787,99 @@ static void mark_map_regs(struct bpf_verifier_state *state, u32 regno,
}
}
+static bool try_match_pkt_pointers(const struct bpf_insn *insn,
+ struct bpf_reg_state *dst_reg,
+ struct bpf_reg_state *src_reg,
+ struct bpf_verifier_state *this_branch,
+ struct bpf_verifier_state *other_branch)
+{
+ if (BPF_SRC(insn->code) != BPF_X)
+ return false;
+
+ switch (BPF_OP(insn->code)) {
+ case BPF_JGT:
+ if ((dst_reg->type == PTR_TO_PACKET &&
+ src_reg->type == PTR_TO_PACKET_END) ||
+ (dst_reg->type == PTR_TO_PACKET_META &&
+ reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) {
+ /* pkt_data' > pkt_end, pkt_meta' > pkt_data */
+ find_good_pkt_pointers(this_branch, dst_reg,
+ dst_reg->type, false);
+ } else if ((dst_reg->type == PTR_TO_PACKET_END &&
+ src_reg->type == PTR_TO_PACKET) ||
+ (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) &&
+ src_reg->type == PTR_TO_PACKET_META)) {
+ /* pkt_end > pkt_data', pkt_data > pkt_meta' */
+ find_good_pkt_pointers(other_branch, src_reg,
+ src_reg->type, true);
+ } else {
+ return false;
+ }
+ break;
+ case BPF_JLT:
+ if ((dst_reg->type == PTR_TO_PACKET &&
+ src_reg->type == PTR_TO_PACKET_END) ||
+ (dst_reg->type == PTR_TO_PACKET_META &&
+ reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) {
+ /* pkt_data' < pkt_end, pkt_meta' < pkt_data */
+ find_good_pkt_pointers(other_branch, dst_reg,
+ dst_reg->type, true);
+ } else if ((dst_reg->type == PTR_TO_PACKET_END &&
+ src_reg->type == PTR_TO_PACKET) ||
+ (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) &&
+ src_reg->type == PTR_TO_PACKET_META)) {
+ /* pkt_end < pkt_data', pkt_data > pkt_meta' */
+ find_good_pkt_pointers(this_branch, src_reg,
+ src_reg->type, false);
+ } else {
+ return false;
+ }
+ break;
+ case BPF_JGE:
+ if ((dst_reg->type == PTR_TO_PACKET &&
+ src_reg->type == PTR_TO_PACKET_END) ||
+ (dst_reg->type == PTR_TO_PACKET_META &&
+ reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) {
+ /* pkt_data' >= pkt_end, pkt_meta' >= pkt_data */
+ find_good_pkt_pointers(this_branch, dst_reg,
+ dst_reg->type, true);
+ } else if ((dst_reg->type == PTR_TO_PACKET_END &&
+ src_reg->type == PTR_TO_PACKET) ||
+ (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) &&
+ src_reg->type == PTR_TO_PACKET_META)) {
+ /* pkt_end >= pkt_data', pkt_data >= pkt_meta' */
+ find_good_pkt_pointers(other_branch, src_reg,
+ src_reg->type, false);
+ } else {
+ return false;
+ }
+ break;
+ case BPF_JLE:
+ if ((dst_reg->type == PTR_TO_PACKET &&
+ src_reg->type == PTR_TO_PACKET_END) ||
+ (dst_reg->type == PTR_TO_PACKET_META &&
+ reg_is_init_pkt_pointer(src_reg, PTR_TO_PACKET))) {
+ /* pkt_data' <= pkt_end, pkt_meta' <= pkt_data */
+ find_good_pkt_pointers(other_branch, dst_reg,
+ dst_reg->type, false);
+ } else if ((dst_reg->type == PTR_TO_PACKET_END &&
+ src_reg->type == PTR_TO_PACKET) ||
+ (reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) &&
+ src_reg->type == PTR_TO_PACKET_META)) {
+ /* pkt_end <= pkt_data', pkt_data <= pkt_meta' */
+ find_good_pkt_pointers(this_branch, src_reg,
+ src_reg->type, true);
+ } else {
+ return false;
+ }
+ break;
+ default:
+ return false;
+ }
+
+ return true;
+}
+
static int check_cond_jmp_op(struct bpf_verifier_env *env,
struct bpf_insn *insn, int *insn_idx)
{
@@ -2893,75 +2986,9 @@ static int check_cond_jmp_op(struct bpf_verifier_env *env,
*/
mark_map_regs(this_branch, insn->dst_reg, opcode == BPF_JNE);
mark_map_regs(other_branch, insn->dst_reg, opcode == BPF_JEQ);
- } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JGT &&
- dst_reg->type == PTR_TO_PACKET &&
- regs[insn->src_reg].type == PTR_TO_PACKET_END) {
- /* pkt_data' > pkt_end */
- find_good_pkt_pointers(this_branch, dst_reg,
- PTR_TO_PACKET, false);
- } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JGT &&
- dst_reg->type == PTR_TO_PACKET_END &&
- regs[insn->src_reg].type == PTR_TO_PACKET) {
- /* pkt_end > pkt_data' */
- find_good_pkt_pointers(other_branch, ®s[insn->src_reg],
- PTR_TO_PACKET, true);
- } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JLT &&
- dst_reg->type == PTR_TO_PACKET &&
- regs[insn->src_reg].type == PTR_TO_PACKET_END) {
- /* pkt_data' < pkt_end */
- find_good_pkt_pointers(other_branch, dst_reg, PTR_TO_PACKET,
- true);
- } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JLT &&
- dst_reg->type == PTR_TO_PACKET_END &&
- regs[insn->src_reg].type == PTR_TO_PACKET) {
- /* pkt_end < pkt_data' */
- find_good_pkt_pointers(this_branch, ®s[insn->src_reg],
- PTR_TO_PACKET, false);
- } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JGE &&
- dst_reg->type == PTR_TO_PACKET &&
- regs[insn->src_reg].type == PTR_TO_PACKET_END) {
- /* pkt_data' >= pkt_end */
- find_good_pkt_pointers(this_branch, dst_reg,
- PTR_TO_PACKET, true);
- } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JGE &&
- dst_reg->type == PTR_TO_PACKET_END &&
- regs[insn->src_reg].type == PTR_TO_PACKET) {
- /* pkt_end >= pkt_data' */
- find_good_pkt_pointers(other_branch, ®s[insn->src_reg],
- PTR_TO_PACKET, false);
- } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JLE &&
- dst_reg->type == PTR_TO_PACKET &&
- regs[insn->src_reg].type == PTR_TO_PACKET_END) {
- /* pkt_data' <= pkt_end */
- find_good_pkt_pointers(other_branch, dst_reg,
- PTR_TO_PACKET, false);
- } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JLE &&
- dst_reg->type == PTR_TO_PACKET_END &&
- regs[insn->src_reg].type == PTR_TO_PACKET) {
- /* pkt_end <= pkt_data' */
- find_good_pkt_pointers(this_branch, ®s[insn->src_reg],
- PTR_TO_PACKET, true);
- } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JGT &&
- dst_reg->type == PTR_TO_PACKET_META &&
- reg_is_init_pkt_pointer(®s[insn->src_reg], PTR_TO_PACKET)) {
- find_good_pkt_pointers(this_branch, dst_reg,
- PTR_TO_PACKET_META, false);
- } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JLT &&
- dst_reg->type == PTR_TO_PACKET_META &&
- reg_is_init_pkt_pointer(®s[insn->src_reg], PTR_TO_PACKET)) {
- find_good_pkt_pointers(other_branch, dst_reg,
- PTR_TO_PACKET_META, false);
- } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JGE &&
- reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) &&
- regs[insn->src_reg].type == PTR_TO_PACKET_META) {
- find_good_pkt_pointers(other_branch, ®s[insn->src_reg],
- PTR_TO_PACKET_META, false);
- } else if (BPF_SRC(insn->code) == BPF_X && opcode == BPF_JLE &&
- reg_is_init_pkt_pointer(dst_reg, PTR_TO_PACKET) &&
- regs[insn->src_reg].type == PTR_TO_PACKET_META) {
- find_good_pkt_pointers(this_branch, ®s[insn->src_reg],
- PTR_TO_PACKET_META, false);
- } else if (is_pointer_value(env, insn->dst_reg)) {
+ } else if (!try_match_pkt_pointers(insn, dst_reg, ®s[insn->src_reg],
+ this_branch, other_branch) &&
+ is_pointer_value(env, insn->dst_reg)) {
verbose(env, "R%d pointer comparison prohibited\n",
insn->dst_reg);
return -EACCES;
--
1.9.3
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