selftests: bpf: Check bpf_msg_push_data return value

bpf_msg_push_data may return a non-zero value to indicate an error. The
return value should be checked to prevent undetected errors.

To indicate an error, the BPF programs now perform a different action
than their intended one to make the userspace test program notice the
error, i.e., the programs supposed to pass/redirect drop, the program
supposed to drop passes.

Fixes: 84fbfe026acaa ("bpf: test_sockmap add options to use msg_push_data")
Signed-off-by: Felix Maurer <fmaurer@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/89f767bb44005d6b4dd1f42038c438f76b3ebfad.1644601294.git.fmaurer@redhat.com

diff --git a/tools/testing/selftests/bpf/progs/test_sockmap_kern.h b/tools/testing/selftests/bpf/progs/test_sockmap_kern.h
index 2966564b8497aa4cd03049a209e2044e580a652c..6c85b00f27b2e5e795bc3fa9dbb21c50d9999ece 100644 (file)
--- a/tools/testing/selftests/bpf/progs/test_sockmap_kern.h
+++ b/tools/testing/selftests/bpf/progs/test_sockmap_kern.h
@@ -235,7 +235,7 @@ SEC("sk_msg1")
 int bpf_prog4(struct sk_msg_md *msg)
 {
        int *bytes, zero = 0, one = 1, two = 2, three = 3, four = 4, five = 5;
-       int *start, *end, *start_push, *end_push, *start_pop, *pop;
+       int *start, *end, *start_push, *end_push, *start_pop, *pop, err = 0;
 
        bytes = bpf_map_lookup_elem(&sock_apply_bytes, &zero);
        if (bytes)
@@ -249,8 +249,11 @@ int bpf_prog4(struct sk_msg_md *msg)
                bpf_msg_pull_data(msg, *start, *end, 0);
        start_push = bpf_map_lookup_elem(&sock_bytes, &two);
        end_push = bpf_map_lookup_elem(&sock_bytes, &three);
-       if (start_push && end_push)
-               bpf_msg_push_data(msg, *start_push, *end_push, 0);
+       if (start_push && end_push) {
+               err = bpf_msg_push_data(msg, *start_push, *end_push, 0);
+               if (err)
+                       return SK_DROP;
+       }
        start_pop = bpf_map_lookup_elem(&sock_bytes, &four);
        pop = bpf_map_lookup_elem(&sock_bytes, &five);
        if (start_pop && pop)
@@ -263,6 +266,7 @@ int bpf_prog6(struct sk_msg_md *msg)
 {
        int zero = 0, one = 1, two = 2, three = 3, four = 4, five = 5, key = 0;
        int *bytes, *start, *end, *start_push, *end_push, *start_pop, *pop, *f;
+       int err = 0;
        __u64 flags = 0;
 
        bytes = bpf_map_lookup_elem(&sock_apply_bytes, &zero);
@@ -279,8 +283,11 @@ int bpf_prog6(struct sk_msg_md *msg)
 
        start_push = bpf_map_lookup_elem(&sock_bytes, &two);
        end_push = bpf_map_lookup_elem(&sock_bytes, &three);
-       if (start_push && end_push)
-               bpf_msg_push_data(msg, *start_push, *end_push, 0);
+       if (start_push && end_push) {
+               err = bpf_msg_push_data(msg, *start_push, *end_push, 0);
+               if (err)
+                       return SK_DROP;
+       }
 
        start_pop = bpf_map_lookup_elem(&sock_bytes, &four);
        pop = bpf_map_lookup_elem(&sock_bytes, &five);
@@ -338,7 +345,7 @@ SEC("sk_msg5")
 int bpf_prog10(struct sk_msg_md *msg)
 {
        int *bytes, *start, *end, *start_push, *end_push, *start_pop, *pop;
-       int zero = 0, one = 1, two = 2, three = 3, four = 4, five = 5;
+       int zero = 0, one = 1, two = 2, three = 3, four = 4, five = 5, err = 0;
 
        bytes = bpf_map_lookup_elem(&sock_apply_bytes, &zero);
        if (bytes)
@@ -352,8 +359,11 @@ int bpf_prog10(struct sk_msg_md *msg)
                bpf_msg_pull_data(msg, *start, *end, 0);
        start_push = bpf_map_lookup_elem(&sock_bytes, &two);
        end_push = bpf_map_lookup_elem(&sock_bytes, &three);
-       if (start_push && end_push)
-               bpf_msg_push_data(msg, *start_push, *end_push, 0);
+       if (start_push && end_push) {
+               err = bpf_msg_push_data(msg, *start_push, *end_push, 0);
+               if (err)
+                       return SK_PASS;
+       }
        start_pop = bpf_map_lookup_elem(&sock_bytes, &four);
        pop = bpf_map_lookup_elem(&sock_bytes, &five);
        if (start_pop && pop)