6.1-stable review patch. If anyone has any objections, please let me know.
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From: Martin KaFai Lau martin.lau@kernel.org
[ Upstream commit b69d4413aa1961930fbf9ffad8376d577378daf9 ]
The netkit program is not a cgroup bpf program and should not be shown in the output of the "bpftool cgroup show" command.
However, if the netkit device happens to have ifindex 3, the "bpftool cgroup show" command will output the netkit bpf program as well:
ip -d link show dev nk1
3: nk1@if2: ... link/ether ... netkit mode ...
bpftool net show
tc: nk1(3) netkit/peer tw_ns_nk2phy prog_id 469447
bpftool cgroup show /sys/fs/cgroup/...
ID AttachType AttachFlags Name ... ... ... 469447 netkit_peer tw_ns_nk2phy
The reason is that the target_fd (which is the cgroup_fd here) and the target_ifindex are in a union in the uapi/linux/bpf.h. The bpftool iterates all values in "enum bpf_attach_type" which includes non cgroup attach types like netkit. The cgroup_fd is usually 3 here, so the bug is triggered when the netkit ifindex just happens to be 3 as well.
The bpftool's cgroup.c already has a list of cgroup-only attach type defined in "cgroup_attach_types[]". This patch fixes it by iterating over "cgroup_attach_types[]" instead of "__MAX_BPF_ATTACH_TYPE".
Cc: Quentin Monnet qmo@kernel.org Reported-by: Takshak Chahande ctakshak@meta.com Signed-off-by: Martin KaFai Lau martin.lau@kernel.org Acked-by: Daniel Borkmann daniel@iogearbox.net Reviewed-by: Quentin Monnet qmo@kernel.org Link: https://lore.kernel.org/r/20250507203232.1420762-1-martin.lau@linux.dev Signed-off-by: Alexei Starovoitov ast@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- tools/bpf/bpftool/cgroup.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/tools/bpf/bpftool/cgroup.c b/tools/bpf/bpftool/cgroup.c index b46a998d8f8df..d157f58ec7d5a 100644 --- a/tools/bpf/bpftool/cgroup.c +++ b/tools/bpf/bpftool/cgroup.c @@ -284,11 +284,11 @@ static int show_bpf_progs(int cgroup_fd, enum bpf_attach_type type,
static int do_show(int argc, char **argv) { - enum bpf_attach_type type; int has_attached_progs; const char *path; int cgroup_fd; int ret = -1; + unsigned int i;
query_flags = 0;
@@ -336,14 +336,14 @@ static int do_show(int argc, char **argv) "AttachFlags", "Name");
btf_vmlinux = libbpf_find_kernel_btf(); - for (type = 0; type < __MAX_BPF_ATTACH_TYPE; type++) { + for (i = 0; i < ARRAY_SIZE(cgroup_attach_types); i++) { /* * Not all attach types may be supported, so it's expected, * that some requests will fail. * If we were able to get the show for at least one * attach type, let's return 0. */ - if (show_bpf_progs(cgroup_fd, type, 0) == 0) + if (show_bpf_progs(cgroup_fd, cgroup_attach_types[i], 0) == 0) ret = 0; }
@@ -366,9 +366,9 @@ static int do_show(int argc, char **argv) static int do_show_tree_fn(const char *fpath, const struct stat *sb, int typeflag, struct FTW *ftw) { - enum bpf_attach_type type; int has_attached_progs; int cgroup_fd; + unsigned int i;
if (typeflag != FTW_D) return 0; @@ -400,8 +400,8 @@ static int do_show_tree_fn(const char *fpath, const struct stat *sb, }
btf_vmlinux = libbpf_find_kernel_btf(); - for (type = 0; type < __MAX_BPF_ATTACH_TYPE; type++) - show_bpf_progs(cgroup_fd, type, ftw->level); + for (i = 0; i < ARRAY_SIZE(cgroup_attach_types); i++) + show_bpf_progs(cgroup_fd, cgroup_attach_types[i], ftw->level);
if (errno == EINVAL) /* Last attach type does not support query.