From edfa9af0a73ecc2000d7bb81d0b0fd3158cc9a65 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Sat, 7 Oct 2023 00:06:50 +0200 Subject: bpf: Handle bpf_mprog_query with NULL entry Improve consistency for bpf_mprog_query() API and let the latter also handle a NULL entry as can be the case for tcx. Instead of returning -ENOENT, we copy a count of 0 and revision of 1 to user space, so that this can be fed into a subsequent bpf_mprog_attach() call as expected_revision. A BPF self- test as part of this series has been added to assert this case. Suggested-by: Lorenz Bauer Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/r/20231006220655.1653-2-daniel@iogearbox.net Signed-off-by: Martin KaFai Lau --- kernel/bpf/mprog.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) (limited to 'kernel/bpf/mprog.c') diff --git a/kernel/bpf/mprog.c b/kernel/bpf/mprog.c index 007d98c799e2..1394168062e8 100644 --- a/kernel/bpf/mprog.c +++ b/kernel/bpf/mprog.c @@ -401,14 +401,16 @@ int bpf_mprog_query(const union bpf_attr *attr, union bpf_attr __user *uattr, struct bpf_mprog_cp *cp; struct bpf_prog *prog; const u32 flags = 0; + u32 id, count = 0; + u64 revision = 1; int i, ret = 0; - u32 id, count; - u64 revision; if (attr->query.query_flags || attr->query.attach_flags) return -EINVAL; - revision = bpf_mprog_revision(entry); - count = bpf_mprog_total(entry); + if (entry) { + revision = bpf_mprog_revision(entry); + count = bpf_mprog_total(entry); + } if (copy_to_user(&uattr->query.attach_flags, &flags, sizeof(flags))) return -EFAULT; if (copy_to_user(&uattr->query.revision, &revision, sizeof(revision))) -- cgit v1.2.3-70-g09d2