selftests/bpf: add verifier tests for wide stores

Make sure that wide stores are allowed at proper (aligned) addresses.
Note that user_ip6 is naturally aligned on 8-byte boundary, so
correct addresses are user_ip6[0] and user_ip6[2]. msg_src_ip6 is,
however, aligned on a 4-byte bondary, so only msg_src_ip6[1]
can be wide-stored.

Cc: Andrii Nakryiko <andriin@fb.com>
Cc: Yonghong Song <yhs@fb.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools/testing/selftests/bpf/test_verifier.c

@@ -105,6 +105,7 @@ struct bpf_test {
 			__u64 data64[TEST_DATA_LEN / 8];
 		};
 	} retvals[MAX_TEST_RUNS];
+	enum bpf_attach_type expected_attach_type;
 };
 
 /* Note we want this to be 64 bit aligned so that the end of our array is
@@ -850,6 +851,7 @@ static void do_test_single(struct bpf_test *test, bool unpriv,
 	int fd_prog, expected_ret, alignment_prevented_execution;
 	int prog_len, prog_type = test->prog_type;
 	struct bpf_insn *prog = test->insns;
+	struct bpf_load_program_attr attr;
 	int run_errs, run_successes;
 	int map_fds[MAX_NR_MAPS];
 	const char *expected_err;
@@ -881,8 +883,17 @@ static void do_test_single(struct bpf_test *test, bool unpriv,
 		pflags |= BPF_F_STRICT_ALIGNMENT;
 	if (test->flags & F_NEEDS_EFFICIENT_UNALIGNED_ACCESS)
 		pflags |= BPF_F_ANY_ALIGNMENT;
-	fd_prog = bpf_verify_program(prog_type, prog, prog_len, pflags,
-				     "GPL", 0, bpf_vlog, sizeof(bpf_vlog), 4);
+
+	memset(&attr, 0, sizeof(attr));
+	attr.prog_type = prog_type;
+	attr.expected_attach_type = test->expected_attach_type;
+	attr.insns = prog;
+	attr.insns_cnt = prog_len;
+	attr.license = "GPL";
+	attr.log_level = 4;
+	attr.prog_flags = pflags;
+
+	fd_prog = bpf_load_program_xattr(&attr, bpf_vlog, sizeof(bpf_vlog));
 	if (fd_prog < 0 && !bpf_probe_prog_type(prog_type, 0)) {
 		printf("SKIP (unsupported program type %d)\n", prog_type);
 		skips++;
@@ -912,7 +923,7 @@ static void do_test_single(struct bpf_test *test, bool unpriv,
 			printf("FAIL\nUnexpected success to load!\n");
 			goto fail_log;
 		}
-		if (!strstr(bpf_vlog, expected_err)) {
+		if (!expected_err || !strstr(bpf_vlog, expected_err)) {
 			printf("FAIL\nUnexpected error message!\n\tEXP: %s\n\tRES: %s\n",
 			      expected_err, bpf_vlog);
 			goto fail_log;

tools/testing/selftests/bpf/verifier/wide_store.c

+#define BPF_SOCK_ADDR(field, off, res, err) \
+{ \
+	"wide store to bpf_sock_addr." #field "[" #off "]", \
+	.insns = { \
+	BPF_MOV64_IMM(BPF_REG_0, 1), \
+	BPF_STX_MEM(BPF_DW, BPF_REG_1, BPF_REG_0, \
+		    offsetof(struct bpf_sock_addr, field[off])), \
+	BPF_EXIT_INSN(), \
+	}, \
+	.result = res, \
+	.prog_type = BPF_PROG_TYPE_CGROUP_SOCK_ADDR, \
+	.expected_attach_type = BPF_CGROUP_UDP6_SENDMSG, \
+	.errstr = err, \
+}
+
+/* user_ip6[0] is u64 aligned */
+BPF_SOCK_ADDR(user_ip6, 0, ACCEPT,
+	      NULL),
+BPF_SOCK_ADDR(user_ip6, 1, REJECT,
+	      "invalid bpf_context access off=12 size=8"),
+BPF_SOCK_ADDR(user_ip6, 2, ACCEPT,
+	      NULL),
+BPF_SOCK_ADDR(user_ip6, 3, REJECT,
+	      "invalid bpf_context access off=20 size=8"),
+
+/* msg_src_ip6[0] is _not_ u64 aligned */
+BPF_SOCK_ADDR(msg_src_ip6, 0, REJECT,
+	      "invalid bpf_context access off=44 size=8"),
+BPF_SOCK_ADDR(msg_src_ip6, 1, ACCEPT,
+	      NULL),
+BPF_SOCK_ADDR(msg_src_ip6, 2, REJECT,
+	      "invalid bpf_context access off=52 size=8"),
+BPF_SOCK_ADDR(msg_src_ip6, 3, REJECT,
+	      "invalid bpf_context access off=56 size=8"),
+
+#undef BPF_SOCK_ADDR