diff --git a/net/core/filter.c b/net/core/filter.c index 03655f2074ae..a7044e98765e 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -10989,13 +10989,24 @@ static bool sk_lookup_is_valid_access(int off, int size, case bpf_ctx_range(struct bpf_sk_lookup, local_ip4): case bpf_ctx_range_till(struct bpf_sk_lookup, remote_ip6[0], remote_ip6[3]): case bpf_ctx_range_till(struct bpf_sk_lookup, local_ip6[0], local_ip6[3]): - case offsetof(struct bpf_sk_lookup, remote_port) ... - offsetof(struct bpf_sk_lookup, local_ip4) - 1: case bpf_ctx_range(struct bpf_sk_lookup, local_port): case bpf_ctx_range(struct bpf_sk_lookup, ingress_ifindex): bpf_ctx_record_field_size(info, sizeof(__u32)); return bpf_ctx_narrow_access_ok(off, size, sizeof(__u32)); + case bpf_ctx_range(struct bpf_sk_lookup, remote_port): + /* Allow 4-byte access to 2-byte field for backward compatibility */ + if (size == sizeof(__u32)) + return true; + bpf_ctx_record_field_size(info, sizeof(__be16)); + return bpf_ctx_narrow_access_ok(off, size, sizeof(__be16)); + + case offsetofend(struct bpf_sk_lookup, remote_port) ... + offsetof(struct bpf_sk_lookup, local_ip4) - 1: + /* Allow access to zero padding for backward compatibility */ + bpf_ctx_record_field_size(info, sizeof(__u16)); + return bpf_ctx_narrow_access_ok(off, size, sizeof(__u16)); + default: return false; } @@ -11077,6 +11088,11 @@ static u32 sk_lookup_convert_ctx_access(enum bpf_access_type type, sport, 2, target_size)); break; + case offsetofend(struct bpf_sk_lookup, remote_port): + *target_size = 2; + *insn++ = BPF_MOV32_IMM(si->dst_reg, 0); + break; + case offsetof(struct bpf_sk_lookup, local_port): *insn++ = BPF_LDX_MEM(BPF_H, si->dst_reg, si->src_reg, bpf_target_off(struct bpf_sk_lookup_kern, diff --git a/tools/testing/selftests/bpf/progs/test_sk_lookup.c b/tools/testing/selftests/bpf/progs/test_sk_lookup.c index bf5b7caefdd0..6058dcb11b36 100644 --- a/tools/testing/selftests/bpf/progs/test_sk_lookup.c +++ b/tools/testing/selftests/bpf/progs/test_sk_lookup.c @@ -413,15 +413,20 @@ int ctx_narrow_access(struct bpf_sk_lookup *ctx) /* Narrow loads from remote_port field. Expect SRC_PORT. */ if (LSB(ctx->remote_port, 0) != ((SRC_PORT >> 0) & 0xff) || - LSB(ctx->remote_port, 1) != ((SRC_PORT >> 8) & 0xff) || - LSB(ctx->remote_port, 2) != 0 || LSB(ctx->remote_port, 3) != 0) + LSB(ctx->remote_port, 1) != ((SRC_PORT >> 8) & 0xff)) return SK_DROP; if (LSW(ctx->remote_port, 0) != SRC_PORT) return SK_DROP; - /* Load from remote_port field with zero padding (backward compatibility) */ + /* + * NOTE: 4-byte load from bpf_sk_lookup at remote_port offset + * is quirky. It gets rewritten by the access converter to a + * 2-byte load for backward compatibility. Treating the load + * result as a be16 value makes the code portable across + * little- and big-endian platforms. + */ val_u32 = *(__u32 *)&ctx->remote_port; - if (val_u32 != bpf_htonl(bpf_ntohs(SRC_PORT) << 16)) + if (val_u32 != SRC_PORT) return SK_DROP; /* Narrow loads from local_port field. Expect DST_PORT. */