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authorDaniel Borkmann <daniel@iogearbox.net>2023-10-07 00:06:49 +0200
committerMartin KaFai Lau <martin.lau@kernel.org>2023-10-06 17:11:20 -0700
commita4fe78386afb94780f8e6fcd10a67c4d4dfe4da8 (patch)
treeb11380d239cac40d0a7f6de2bcbaeb64795917e8 /kernel
parentc4d49196ceec80e30e8d981410d73331b49b7850 (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 <lmb@isovalent.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/r/20231006220655.1653-1-daniel@iogearbox.net Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/bpf/syscall.c2
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)