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authorAlexei Starovoitov <ast@fb.com>2017-03-25 01:57:33 +0300
committerDavid S. Miller <davem@davemloft.net>2017-03-25 06:51:28 +0300
commitb1977682a3858b5584ffea7cfb7bd863f68db18d (patch)
treef255d32b2a4e2b72811b36bbd04b27ef9fd2a947 /tools
parent43a6684519ab0a6c52024b5e25322476cabad893 (diff)
downloadlinux-b1977682a3858b5584ffea7cfb7bd863f68db18d.tar.xz
bpf: improve verifier packet range checks
llvm can optimize the 'if (ptr > data_end)' checks to be in the order slightly different than the original C code which will confuse verifier. Like: if (ptr + 16 > data_end) return TC_ACT_SHOT; // may be followed by if (ptr + 14 > data_end) return TC_ACT_SHOT; while llvm can see that 'ptr' is valid for all 16 bytes, the verifier could not. Fix verifier logic to account for such case and add a test. Reported-by: Huapeng Zhou <hzhou@fb.com> Fixes: 969bf05eb3ce ("bpf: direct packet access") Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Martin KaFai Lau <kafai@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'tools')
-rw-r--r--tools/testing/selftests/bpf/test_verifier.c20
1 files changed, 20 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
index d1555e4240c0..7d761d4cc759 100644
--- a/tools/testing/selftests/bpf/test_verifier.c
+++ b/tools/testing/selftests/bpf/test_verifier.c
@@ -3418,6 +3418,26 @@ static struct bpf_test tests[] = {
.prog_type = BPF_PROG_TYPE_LWT_XMIT,
},
{
+ "overlapping checks for direct packet access",
+ .insns = {
+ BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1,
+ offsetof(struct __sk_buff, data)),
+ BPF_LDX_MEM(BPF_W, BPF_REG_3, BPF_REG_1,
+ offsetof(struct __sk_buff, data_end)),
+ BPF_MOV64_REG(BPF_REG_0, BPF_REG_2),
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_0, 8),
+ BPF_JMP_REG(BPF_JGT, BPF_REG_0, BPF_REG_3, 4),
+ BPF_MOV64_REG(BPF_REG_1, BPF_REG_2),
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, 6),
+ BPF_JMP_REG(BPF_JGT, BPF_REG_1, BPF_REG_3, 1),
+ BPF_LDX_MEM(BPF_H, BPF_REG_0, BPF_REG_2, 6),
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .result = ACCEPT,
+ .prog_type = BPF_PROG_TYPE_LWT_XMIT,
+ },
+ {
"invalid access of tc_classid for LWT_IN",
.insns = {
BPF_LDX_MEM(BPF_W, BPF_REG_0, BPF_REG_1,