From e710bcc6d92c47bb7d8e803b41ef529c09ad6a9e Mon Sep 17 00:00:00 2001 From: Martin KaFai Lau Date: Mon, 19 Oct 2020 12:42:19 -0700 Subject: bpf: selftest: Ensure the return value of bpf_skc_to helpers must be checked This patch tests: int bpf_cls(struct __sk_buff *skb) { /* REG_6: sk * REG_7: tp * REG_8: req_sk */ sk = skb->sk; if (!sk) return 0; tp = bpf_skc_to_tcp_sock(sk); req_sk = bpf_skc_to_tcp_request_sock(sk); if (!req_sk) return 0; /* !tp has not been tested, so verifier should reject. */ return *(__u8 *)tp; } Signed-off-by: Martin KaFai Lau Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20201019194219.1051314-1-kafai@fb.com --- tools/testing/selftests/bpf/verifier/sock.c | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/tools/testing/selftests/bpf/verifier/sock.c b/tools/testing/selftests/bpf/verifier/sock.c index b1aac2641498..ce13ece08d51 100644 --- a/tools/testing/selftests/bpf/verifier/sock.c +++ b/tools/testing/selftests/bpf/verifier/sock.c @@ -631,3 +631,28 @@ .prog_type = BPF_PROG_TYPE_SK_REUSEPORT, .result = ACCEPT, }, +{ + "mark null check on return value of bpf_skc_to helpers", + .insns = { + BPF_LDX_MEM(BPF_DW, BPF_REG_1, BPF_REG_1, offsetof(struct __sk_buff, sk)), + BPF_JMP_IMM(BPF_JNE, BPF_REG_1, 0, 2), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + BPF_MOV64_REG(BPF_REG_6, BPF_REG_1), + BPF_EMIT_CALL(BPF_FUNC_skc_to_tcp_sock), + BPF_MOV64_REG(BPF_REG_7, BPF_REG_0), + BPF_MOV64_REG(BPF_REG_1, BPF_REG_6), + BPF_EMIT_CALL(BPF_FUNC_skc_to_tcp_request_sock), + BPF_MOV64_REG(BPF_REG_8, BPF_REG_0), + BPF_JMP_IMM(BPF_JNE, BPF_REG_8, 0, 2), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + BPF_LDX_MEM(BPF_B, BPF_REG_0, BPF_REG_7, 0), + BPF_EXIT_INSN(), + }, + .prog_type = BPF_PROG_TYPE_SCHED_CLS, + .result = REJECT, + .errstr = "invalid mem access", + .result_unpriv = REJECT, + .errstr_unpriv = "unknown func", +}, -- cgit v1.2.3