selftests/bpf: Fix endianness issues in sk_lookup/ctx_narrow_access

This test makes a lot of narrow load checks while assuming little
endian architecture, and therefore fails on s390.

Fix by introducing LSB and LSW macros and using them to perform narrow
loads.

Fixes: 0ab5539f8584 ("selftests/bpf: Tests for BPF_SK_LOOKUP attach point")
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200929201814.44360-1-iii@linux.ibm.com

diff --git a/tools/testing/selftests/bpf/progs/test_sk_lookup.c b/tools/testing/selftests/bpf/progs/test_sk_lookup.c
index bbf8296f4d66336b2776ba0faa073f01cea92934..1032b292af5b784229c2b2da7fffb753703e12d7 100644 (file)
--- a/tools/testing/selftests/bpf/progs/test_sk_lookup.c
+++ b/tools/testing/selftests/bpf/progs/test_sk_lookup.c
@@ -19,6 +19,17 @@
 #define IP6(aaaa, bbbb, cccc, dddd)                    \
        { bpf_htonl(aaaa), bpf_htonl(bbbb), bpf_htonl(cccc), bpf_htonl(dddd) }
 
+/* Macros for least-significant byte and word accesses. */
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+#define LSE_INDEX(index, size) (index)
+#else
+#define LSE_INDEX(index, size) ((size) - (index) - 1)
+#endif
+#define LSB(value, index)                              \
+       (((__u8 *)&(value))[LSE_INDEX((index), sizeof(value))])
+#define LSW(value, index)                              \
+       (((__u16 *)&(value))[LSE_INDEX((index), sizeof(value) / 2)])
+
 #define MAX_SOCKS 32
 
 struct {
@@ -369,171 +380,146 @@ int ctx_narrow_access(struct bpf_sk_lookup *ctx)
 {
        struct bpf_sock *sk;
        int err, family;
-       __u16 *half;
-       __u8 *byte;
        bool v4;
 
        v4 = (ctx->family == AF_INET);
 
        /* Narrow loads from family field */
-       byte = (__u8 *)&ctx->family;
-       half = (__u16 *)&ctx->family;
-       if (byte[0] != (v4 ? AF_INET : AF_INET6) ||
-           byte[1] != 0 || byte[2] != 0 || byte[3] != 0)
+       if (LSB(ctx->family, 0) != (v4 ? AF_INET : AF_INET6) ||
+           LSB(ctx->family, 1) != 0 || LSB(ctx->family, 2) != 0 || LSB(ctx->family, 3) != 0)
                return SK_DROP;
-       if (half[0] != (v4 ? AF_INET : AF_INET6))
+       if (LSW(ctx->family, 0) != (v4 ? AF_INET : AF_INET6))
                return SK_DROP;
 
-       byte = (__u8 *)&ctx->protocol;
-       if (byte[0] != IPPROTO_TCP ||
-           byte[1] != 0 || byte[2] != 0 || byte[3] != 0)
+       /* Narrow loads from protocol field */
+       if (LSB(ctx->protocol, 0) != IPPROTO_TCP ||
+           LSB(ctx->protocol, 1) != 0 || LSB(ctx->protocol, 2) != 0 || LSB(ctx->protocol, 3) != 0)
                return SK_DROP;
-       half = (__u16 *)&ctx->protocol;
-       if (half[0] != IPPROTO_TCP)
+       if (LSW(ctx->protocol, 0) != IPPROTO_TCP)
                return SK_DROP;
 
        /* Narrow loads from remote_port field. Expect non-0 value. */
-       byte = (__u8 *)&ctx->remote_port;
-       if (byte[0] == 0 && byte[1] == 0 && byte[2] == 0 && byte[3] == 0)
+       if (LSB(ctx->remote_port, 0) == 0 && LSB(ctx->remote_port, 1) == 0 &&
+           LSB(ctx->remote_port, 2) == 0 && LSB(ctx->remote_port, 3) == 0)
                return SK_DROP;
-       half = (__u16 *)&ctx->remote_port;
-       if (half[0] == 0)
+       if (LSW(ctx->remote_port, 0) == 0)
                return SK_DROP;
 
        /* Narrow loads from local_port field. Expect DST_PORT. */
-       byte = (__u8 *)&ctx->local_port;
-       if (byte[0] != ((DST_PORT >> 0) & 0xff) ||
-           byte[1] != ((DST_PORT >> 8) & 0xff) ||
-           byte[2] != 0 || byte[3] != 0)
+       if (LSB(ctx->local_port, 0) != ((DST_PORT >> 0) & 0xff) ||
+           LSB(ctx->local_port, 1) != ((DST_PORT >> 8) & 0xff) ||
+           LSB(ctx->local_port, 2) != 0 || LSB(ctx->local_port, 3) != 0)
                return SK_DROP;
-       half = (__u16 *)&ctx->local_port;
-       if (half[0] != DST_PORT)
+       if (LSW(ctx->local_port, 0) != DST_PORT)
                return SK_DROP;
 
        /* Narrow loads from IPv4 fields */
        if (v4) {
                /* Expect non-0.0.0.0 in remote_ip4 */
-               byte = (__u8 *)&ctx->remote_ip4;
-               if (byte[0] == 0 && byte[1] == 0 &&
-                   byte[2] == 0 && byte[3] == 0)
+               if (LSB(ctx->remote_ip4, 0) == 0 && LSB(ctx->remote_ip4, 1) == 0 &&
+                   LSB(ctx->remote_ip4, 2) == 0 && LSB(ctx->remote_ip4, 3) == 0)
                        return SK_DROP;
-               half = (__u16 *)&ctx->remote_ip4;
-               if (half[0] == 0 && half[1] == 0)
+               if (LSW(ctx->remote_ip4, 0) == 0 && LSW(ctx->remote_ip4, 1) == 0)
                        return SK_DROP;
 
                /* Expect DST_IP4 in local_ip4 */
-               byte = (__u8 *)&ctx->local_ip4;
-               if (byte[0] != ((DST_IP4 >>  0) & 0xff) ||
-                   byte[1] != ((DST_IP4 >>  8) & 0xff) ||
-                   byte[2] != ((DST_IP4 >> 16) & 0xff) ||
-                   byte[3] != ((DST_IP4 >> 24) & 0xff))
+               if (LSB(ctx->local_ip4, 0) != ((DST_IP4 >> 0) & 0xff) ||
+                   LSB(ctx->local_ip4, 1) != ((DST_IP4 >> 8) & 0xff) ||
+                   LSB(ctx->local_ip4, 2) != ((DST_IP4 >> 16) & 0xff) ||
+                   LSB(ctx->local_ip4, 3) != ((DST_IP4 >> 24) & 0xff))
                        return SK_DROP;
-               half = (__u16 *)&ctx->local_ip4;
-               if (half[0] != ((DST_IP4 >>  0) & 0xffff) ||
-                   half[1] != ((DST_IP4 >> 16) & 0xffff))
+               if (LSW(ctx->local_ip4, 0) != ((DST_IP4 >> 0) & 0xffff) ||
+                   LSW(ctx->local_ip4, 1) != ((DST_IP4 >> 16) & 0xffff))
                        return SK_DROP;
        } else {
                /* Expect 0.0.0.0 IPs when family != AF_INET */
-               byte = (__u8 *)&ctx->remote_ip4;
-               if (byte[0] != 0 || byte[1] != 0 &&
-                   byte[2] != 0 || byte[3] != 0)
+               if (LSB(ctx->remote_ip4, 0) != 0 || LSB(ctx->remote_ip4, 1) != 0 ||
+                   LSB(ctx->remote_ip4, 2) != 0 || LSB(ctx->remote_ip4, 3) != 0)
                        return SK_DROP;
-               half = (__u16 *)&ctx->remote_ip4;
-               if (half[0] != 0 || half[1] != 0)
+               if (LSW(ctx->remote_ip4, 0) != 0 || LSW(ctx->remote_ip4, 1) != 0)
                        return SK_DROP;
 
-               byte = (__u8 *)&ctx->local_ip4;
-               if (byte[0] != 0 || byte[1] != 0 &&
-                   byte[2] != 0 || byte[3] != 0)
+               if (LSB(ctx->local_ip4, 0) != 0 || LSB(ctx->local_ip4, 1) != 0 ||
+                   LSB(ctx->local_ip4, 2) != 0 || LSB(ctx->local_ip4, 3) != 0)
                        return SK_DROP;
-               half = (__u16 *)&ctx->local_ip4;
-               if (half[0] != 0 || half[1] != 0)
+               if (LSW(ctx->local_ip4, 0) != 0 || LSW(ctx->local_ip4, 1) != 0)
                        return SK_DROP;
        }
 
        /* Narrow loads from IPv6 fields */
        if (!v4) {
-               /* Expenct non-:: IP in remote_ip6 */
-               byte = (__u8 *)&ctx->remote_ip6;
-               if (byte[0] == 0 && byte[1] == 0 &&
-                   byte[2] == 0 && byte[3] == 0 &&
-                   byte[4] == 0 && byte[5] == 0 &&
-                   byte[6] == 0 && byte[7] == 0 &&
-                   byte[8] == 0 && byte[9] == 0 &&
-                   byte[10] == 0 && byte[11] == 0 &&
-                   byte[12] == 0 && byte[13] == 0 &&
-                   byte[14] == 0 && byte[15] == 0)
+               /* Expect non-:: IP in remote_ip6 */
+               if (LSB(ctx->remote_ip6[0], 0) == 0 && LSB(ctx->remote_ip6[0], 1) == 0 &&
+                   LSB(ctx->remote_ip6[0], 2) == 0 && LSB(ctx->remote_ip6[0], 3) == 0 &&
+                   LSB(ctx->remote_ip6[1], 0) == 0 && LSB(ctx->remote_ip6[1], 1) == 0 &&
+                   LSB(ctx->remote_ip6[1], 2) == 0 && LSB(ctx->remote_ip6[1], 3) == 0 &&
+                   LSB(ctx->remote_ip6[2], 0) == 0 && LSB(ctx->remote_ip6[2], 1) == 0 &&
+                   LSB(ctx->remote_ip6[2], 2) == 0 && LSB(ctx->remote_ip6[2], 3) == 0 &&
+                   LSB(ctx->remote_ip6[3], 0) == 0 && LSB(ctx->remote_ip6[3], 1) == 0 &&
+                   LSB(ctx->remote_ip6[3], 2) == 0 && LSB(ctx->remote_ip6[3], 3) == 0)
                        return SK_DROP;
-               half = (__u16 *)&ctx->remote_ip6;
-               if (half[0] == 0 && half[1] == 0 &&
-                   half[2] == 0 && half[3] == 0 &&
-                   half[4] == 0 && half[5] == 0 &&
-                   half[6] == 0 && half[7] == 0)
+               if (LSW(ctx->remote_ip6[0], 0) == 0 && LSW(ctx->remote_ip6[0], 1) == 0 &&
+                   LSW(ctx->remote_ip6[1], 0) == 0 && LSW(ctx->remote_ip6[1], 1) == 0 &&
+                   LSW(ctx->remote_ip6[2], 0) == 0 && LSW(ctx->remote_ip6[2], 1) == 0 &&
+                   LSW(ctx->remote_ip6[3], 0) == 0 && LSW(ctx->remote_ip6[3], 1) == 0)
                        return SK_DROP;
-
                /* Expect DST_IP6 in local_ip6 */
-               byte = (__u8 *)&ctx->local_ip6;
-               if (byte[0] != ((DST_IP6[0] >>  0) & 0xff) ||
-                   byte[1] != ((DST_IP6[0] >>  8) & 0xff) ||
-                   byte[2] != ((DST_IP6[0] >> 16) & 0xff) ||
-                   byte[3] != ((DST_IP6[0] >> 24) & 0xff) ||
-                   byte[4] != ((DST_IP6[1] >>  0) & 0xff) ||
-                   byte[5] != ((DST_IP6[1] >>  8) & 0xff) ||
-                   byte[6] != ((DST_IP6[1] >> 16) & 0xff) ||
-                   byte[7] != ((DST_IP6[1] >> 24) & 0xff) ||
-                   byte[8] != ((DST_IP6[2] >>  0) & 0xff) ||
-                   byte[9] != ((DST_IP6[2] >>  8) & 0xff) ||
-                   byte[10] != ((DST_IP6[2] >> 16) & 0xff) ||
-                   byte[11] != ((DST_IP6[2] >> 24) & 0xff) ||
-                   byte[12] != ((DST_IP6[3] >>  0) & 0xff) ||
-                   byte[13] != ((DST_IP6[3] >>  8) & 0xff) ||
-                   byte[14] != ((DST_IP6[3] >> 16) & 0xff) ||
-                   byte[15] != ((DST_IP6[3] >> 24) & 0xff))
+               if (LSB(ctx->local_ip6[0], 0) != ((DST_IP6[0] >> 0) & 0xff) ||
+                   LSB(ctx->local_ip6[0], 1) != ((DST_IP6[0] >> 8) & 0xff) ||
+                   LSB(ctx->local_ip6[0], 2) != ((DST_IP6[0] >> 16) & 0xff) ||
+                   LSB(ctx->local_ip6[0], 3) != ((DST_IP6[0] >> 24) & 0xff) ||
+                   LSB(ctx->local_ip6[1], 0) != ((DST_IP6[1] >> 0) & 0xff) ||
+                   LSB(ctx->local_ip6[1], 1) != ((DST_IP6[1] >> 8) & 0xff) ||
+                   LSB(ctx->local_ip6[1], 2) != ((DST_IP6[1] >> 16) & 0xff) ||
+                   LSB(ctx->local_ip6[1], 3) != ((DST_IP6[1] >> 24) & 0xff) ||
+                   LSB(ctx->local_ip6[2], 0) != ((DST_IP6[2] >> 0) & 0xff) ||
+                   LSB(ctx->local_ip6[2], 1) != ((DST_IP6[2] >> 8) & 0xff) ||
+                   LSB(ctx->local_ip6[2], 2) != ((DST_IP6[2] >> 16) & 0xff) ||
+                   LSB(ctx->local_ip6[2], 3) != ((DST_IP6[2] >> 24) & 0xff) ||
+                   LSB(ctx->local_ip6[3], 0) != ((DST_IP6[3] >> 0) & 0xff) ||
+                   LSB(ctx->local_ip6[3], 1) != ((DST_IP6[3] >> 8) & 0xff) ||
+                   LSB(ctx->local_ip6[3], 2) != ((DST_IP6[3] >> 16) & 0xff) ||
+                   LSB(ctx->local_ip6[3], 3) != ((DST_IP6[3] >> 24) & 0xff))
                        return SK_DROP;
-               half = (__u16 *)&ctx->local_ip6;
-               if (half[0] != ((DST_IP6[0] >>  0) & 0xffff) ||
-                   half[1] != ((DST_IP6[0] >> 16) & 0xffff) ||
-                   half[2] != ((DST_IP6[1] >>  0) & 0xffff) ||
-                   half[3] != ((DST_IP6[1] >> 16) & 0xffff) ||
-                   half[4] != ((DST_IP6[2] >>  0) & 0xffff) ||
-                   half[5] != ((DST_IP6[2] >> 16) & 0xffff) ||
-                   half[6] != ((DST_IP6[3] >>  0) & 0xffff) ||
-                   half[7] != ((DST_IP6[3] >> 16) & 0xffff))
+               if (LSW(ctx->local_ip6[0], 0) != ((DST_IP6[0] >> 0) & 0xffff) ||
+                   LSW(ctx->local_ip6[0], 1) != ((DST_IP6[0] >> 16) & 0xffff) ||
+                   LSW(ctx->local_ip6[1], 0) != ((DST_IP6[1] >> 0) & 0xffff) ||
+                   LSW(ctx->local_ip6[1], 1) != ((DST_IP6[1] >> 16) & 0xffff) ||
+                   LSW(ctx->local_ip6[2], 0) != ((DST_IP6[2] >> 0) & 0xffff) ||
+                   LSW(ctx->local_ip6[2], 1) != ((DST_IP6[2] >> 16) & 0xffff) ||
+                   LSW(ctx->local_ip6[3], 0) != ((DST_IP6[3] >> 0) & 0xffff) ||
+                   LSW(ctx->local_ip6[3], 1) != ((DST_IP6[3] >> 16) & 0xffff))
                        return SK_DROP;
        } else {
                /* Expect :: IPs when family != AF_INET6 */
-               byte = (__u8 *)&ctx->remote_ip6;
-               if (byte[0] != 0 || byte[1] != 0 ||
-                   byte[2] != 0 || byte[3] != 0 ||
-                   byte[4] != 0 || byte[5] != 0 ||
-                   byte[6] != 0 || byte[7] != 0 ||
-                   byte[8] != 0 || byte[9] != 0 ||
-                   byte[10] != 0 || byte[11] != 0 ||
-                   byte[12] != 0 || byte[13] != 0 ||
-                   byte[14] != 0 || byte[15] != 0)
+               if (LSB(ctx->remote_ip6[0], 0) != 0 || LSB(ctx->remote_ip6[0], 1) != 0 ||
+                   LSB(ctx->remote_ip6[0], 2) != 0 || LSB(ctx->remote_ip6[0], 3) != 0 ||
+                   LSB(ctx->remote_ip6[1], 0) != 0 || LSB(ctx->remote_ip6[1], 1) != 0 ||
+                   LSB(ctx->remote_ip6[1], 2) != 0 || LSB(ctx->remote_ip6[1], 3) != 0 ||
+                   LSB(ctx->remote_ip6[2], 0) != 0 || LSB(ctx->remote_ip6[2], 1) != 0 ||
+                   LSB(ctx->remote_ip6[2], 2) != 0 || LSB(ctx->remote_ip6[2], 3) != 0 ||
+                   LSB(ctx->remote_ip6[3], 0) != 0 || LSB(ctx->remote_ip6[3], 1) != 0 ||
+                   LSB(ctx->remote_ip6[3], 2) != 0 || LSB(ctx->remote_ip6[3], 3) != 0)
                        return SK_DROP;
-               half = (__u16 *)&ctx->remote_ip6;
-               if (half[0] != 0 || half[1] != 0 ||
-                   half[2] != 0 || half[3] != 0 ||
-                   half[4] != 0 || half[5] != 0 ||
-                   half[6] != 0 || half[7] != 0)
+               if (LSW(ctx->remote_ip6[0], 0) != 0 || LSW(ctx->remote_ip6[0], 1) != 0 ||
+                   LSW(ctx->remote_ip6[1], 0) != 0 || LSW(ctx->remote_ip6[1], 1) != 0 ||
+                   LSW(ctx->remote_ip6[2], 0) != 0 || LSW(ctx->remote_ip6[2], 1) != 0 ||
+                   LSW(ctx->remote_ip6[3], 0) != 0 || LSW(ctx->remote_ip6[3], 1) != 0)
                        return SK_DROP;
 
-               byte = (__u8 *)&ctx->local_ip6;
-               if (byte[0] != 0 || byte[1] != 0 ||
-                   byte[2] != 0 || byte[3] != 0 ||
-                   byte[4] != 0 || byte[5] != 0 ||
-                   byte[6] != 0 || byte[7] != 0 ||
-                   byte[8] != 0 || byte[9] != 0 ||
-                   byte[10] != 0 || byte[11] != 0 ||
-                   byte[12] != 0 || byte[13] != 0 ||
-                   byte[14] != 0 || byte[15] != 0)
+               if (LSB(ctx->local_ip6[0], 0) != 0 || LSB(ctx->local_ip6[0], 1) != 0 ||
+                   LSB(ctx->local_ip6[0], 2) != 0 || LSB(ctx->local_ip6[0], 3) != 0 ||
+                   LSB(ctx->local_ip6[1], 0) != 0 || LSB(ctx->local_ip6[1], 1) != 0 ||
+                   LSB(ctx->local_ip6[1], 2) != 0 || LSB(ctx->local_ip6[1], 3) != 0 ||
+                   LSB(ctx->local_ip6[2], 0) != 0 || LSB(ctx->local_ip6[2], 1) != 0 ||
+                   LSB(ctx->local_ip6[2], 2) != 0 || LSB(ctx->local_ip6[2], 3) != 0 ||
+                   LSB(ctx->local_ip6[3], 0) != 0 || LSB(ctx->local_ip6[3], 1) != 0 ||
+                   LSB(ctx->local_ip6[3], 2) != 0 || LSB(ctx->local_ip6[3], 3) != 0)
                        return SK_DROP;
-               half = (__u16 *)&ctx->local_ip6;
-               if (half[0] != 0 || half[1] != 0 ||
-                   half[2] != 0 || half[3] != 0 ||
-                   half[4] != 0 || half[5] != 0 ||
-                   half[6] != 0 || half[7] != 0)
+               if (LSW(ctx->remote_ip6[0], 0) != 0 || LSW(ctx->remote_ip6[0], 1) != 0 ||
+                   LSW(ctx->remote_ip6[1], 0) != 0 || LSW(ctx->remote_ip6[1], 1) != 0 ||
+                   LSW(ctx->remote_ip6[2], 0) != 0 || LSW(ctx->remote_ip6[2], 1) != 0 ||
+                   LSW(ctx->remote_ip6[3], 0) != 0 || LSW(ctx->remote_ip6[3], 1) != 0)
                        return SK_DROP;
        }