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| author | Paul Chaignon <paul.chaignon@gmail.com> | 2025-10-09 22:12:18 +0200 |
|---|---|---|
| committer | Martin KaFai Lau <martin.lau@kernel.org> | 2025-10-10 10:43:04 -0700 |
| commit | bc3eeb42597a514a0b5286f085d91c8b34e4a532 (patch) | |
| tree | f6bd442ece2caefa9b6f852d1c1976f0cc5ba75a | |
| parent | 8d45d0398d10966b022b96481feb619ae1695de0 (diff) | |
selftests/bpf: Test direct packet access on non-linear skbs
This patch adds new selftests in the direct packet access suite, to
cover the non-linear case. The first six tests cover the behavior of
the bounds check with a non-linear skb. The last test adds a call to
bpf_skb_pull_data() to be able to access the packet.
Note that the size of the linear area includes the L2 header, but for
some program types like cgroup_skb, ctx->data points to the L3 header.
Therefore, a linear area of 22 bytes will have only 8 bytes accessible
to the BPF program (22 - ETH_HLEN). For that reason, the cgroup_skb test
cases access the packet at an offset of 8 bytes.
Signed-off-by: Paul Chaignon <paul.chaignon@gmail.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://patch.msgid.link/ceedbfd719e58f0d49dcceb8592f5e6bd38ce5fe.1760037899.git.paul.chaignon@gmail.com
| -rw-r--r-- | tools/testing/selftests/bpf/progs/verifier_direct_packet_access.c | 58 |
1 files changed, 58 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/progs/verifier_direct_packet_access.c b/tools/testing/selftests/bpf/progs/verifier_direct_packet_access.c index a61897e01a50..911caa8fd1b7 100644 --- a/tools/testing/selftests/bpf/progs/verifier_direct_packet_access.c +++ b/tools/testing/selftests/bpf/progs/verifier_direct_packet_access.c @@ -801,4 +801,62 @@ l0_%=: /* exit(0) */ \ : __clobber_all); } +#define access_test_non_linear(name, type, desc, retval, linear_sz, off) \ + SEC(type) \ + __description("direct packet access: " #name " (non-linear, " type ", " desc ")") \ + __success __retval(retval) \ + __linear_size(linear_sz) \ + __naked void access_non_linear_##name(void) \ + { \ + asm volatile (" \ + r2 = *(u32*)(r1 + %[skb_data]); \ + r3 = *(u32*)(r1 + %[skb_data_end]); \ + r0 = r2; \ + r0 += %[offset]; \ + if r0 > r3 goto l0_%=; \ + r0 = *(u8*)(r0 - 1); \ + r0 = 0; \ + exit; \ + l0_%=: r0 = 1; \ + exit; \ + " : \ + : __imm_const(skb_data, offsetof(struct __sk_buff, data)), \ + __imm_const(skb_data_end, offsetof(struct __sk_buff, data_end)), \ + __imm_const(offset, off) \ + : __clobber_all); \ + } + +access_test_non_linear(test31, "tc", "too short eth", 1, ETH_HLEN, 22); +access_test_non_linear(test32, "tc", "too short 1", 1, 1, 22); +access_test_non_linear(test33, "tc", "long enough", 0, 22, 22); +access_test_non_linear(test34, "cgroup_skb/ingress", "too short eth", 1, ETH_HLEN, 8); +access_test_non_linear(test35, "cgroup_skb/ingress", "too short 1", 1, 1, 8); +access_test_non_linear(test36, "cgroup_skb/ingress", "long enough", 0, 22, 8); + +SEC("tc") +__description("direct packet access: test37 (non-linear, linearized)") +__success __retval(0) +__linear_size(ETH_HLEN) +__naked void access_non_linear_linearized(void) +{ + asm volatile (" \ + r6 = r1; \ + r2 = 22; \ + call %[bpf_skb_pull_data]; \ + r2 = *(u32*)(r6 + %[skb_data]); \ + r3 = *(u32*)(r6 + %[skb_data_end]); \ + r0 = r2; \ + r0 += 22; \ + if r0 > r3 goto l0_%=; \ + r0 = *(u8*)(r0 - 1); \ + exit; \ +l0_%=: r0 = 1; \ + exit; \ +" : + : __imm(bpf_skb_pull_data), + __imm_const(skb_data, offsetof(struct __sk_buff, data)), + __imm_const(skb_data_end, offsetof(struct __sk_buff, data_end)) + : __clobber_all); +} + char _license[] SEC("license") = "GPL"; |