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bpf: check if lsm link ptr is libbpf error

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BPF_RAW_TRACEPOINT_OPEN is expected to work only on x86 and x86_64,
since BPF trampoline is implemented only on these architectures.

Attach probing by bpf_program__attach_lsm already happens in
`bpf_lsm_supported`. The resulting pointer can store libbpf error and
that is the case for unsupported architectures.
Add libbpf error check to `bpf_lsm_supported` so execution does not
reach the point where unit startup fails.
This commit is contained in:
Julia Kartseva 2022-01-07 15:02:57 -08:00
parent 79a67f3ca4
commit f409aa5c63
1 changed files with 4 additions and 3 deletions
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7
src/core/bpf-lsm.c
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@ -45,10 +45,11 @@ static bool bpf_can_link_lsm_program(struct bpf_program *prog) {
assert(prog);
link = sym_bpf_program__attach_lsm(prog);
if (!link)
return -ENOMEM;
return 1;
/* If bpf_program__attach_lsm fails the resulting value stores libbpf error code instead of memory
* pointer. That is the case when the helper is called on architectures where BPF trampoline (hence
* BPF_LSM_MAC attach type) is not supported. */
return sym_libbpf_get_error(link) == 0;
}
static int prepare_restrict_fs_bpf(struct restrict_fs_bpf **ret_obj) {