diff options
| author | Daniel Borkmann <[email protected]> | 2023-10-07 00:06:49 +0200 |
|---|---|---|
| committer | Martin KaFai Lau <[email protected]> | 2023-10-06 17:11:20 -0700 |
| commit | a4fe78386afb94780f8e6fcd10a67c4d4dfe4da8 (patch) | |
| tree | b11380d239cac40d0a7f6de2bcbaeb64795917e8 | |
| parent | c4d49196ceec80e30e8d981410d73331b49b7850 (diff) | |
bpf: Fix BPF_PROG_QUERY last field check
While working on the ebpf-go [0] library integration for bpf_mprog and tcx,
Lorenz noticed that two subsequent BPF_PROG_QUERY requests currently fail. A
typical workflow is to first gather the bpf_mprog count without passing program/
link arrays, followed by the second request which contains the actual array
pointers.
The initial call populates count and revision fields. The second call gets
rejected due to a BPF_PROG_QUERY_LAST_FIELD bug which should point to
query.revision instead of query.link_attach_flags since the former is really
the last member.
It was not noticed in libbpf as bpf_prog_query_opts() always calls bpf(2) with
an on-stack bpf_attr that is memset() each time (and therefore query.revision
was reset to zero).
[0] https://ebpf-go.dev
Fixes: e420bed02507 ("bpf: Add fd-based tcx multi-prog infra with link support")
Reported-by: Lorenz Bauer <[email protected]>
Signed-off-by: Daniel Borkmann <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Martin KaFai Lau <[email protected]>
| -rw-r--r-- | kernel/bpf/syscall.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index eb01c31ed591..453a43695a23 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -3913,7 +3913,7 @@ static int bpf_prog_detach(const union bpf_attr *attr) return ret; } -#define BPF_PROG_QUERY_LAST_FIELD query.link_attach_flags +#define BPF_PROG_QUERY_LAST_FIELD query.revision static int bpf_prog_query(const union bpf_attr *attr, union bpf_attr __user *uattr) |