[PATCH 5.10 25/80] selftests: bpf: Check bpf_msg_push_data return value

Greg Kroah-Hartman
2022-02-28T17:48:42Z

From: Felix Maurer <fmaurer@redhat.com>

commit 61d06f01f9710b327a53492e5add9f972eb909b3 upstream.

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
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
tools/testing/selftests/bpf/progs/test_sockmap_kern.h | 26 ++++++++++++------
1 file changed, 18 insertions(+), 8 deletions(-)

--- 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)