[PATCH v3] bpftool: Query only cgroup-related attach types

[PATCH v3] bpftool: Query only cgroup-related attach types

[Kenta Tada]

When CONFIG_NETKIT=y,
bpftool-cgroup shows error even if the cgroup's path is correct:

$ bpftool cgroup tree /sys/fs/cgroup
CgroupPath
ID       AttachType      AttachFlags     Name
Error: can't query bpf programs attached to /sys/fs/cgroup: No such device or address

From strace and kernel tracing, I found netkit returned ENXIO and this command failed.
I think this AttachType(BPF_NETKIT_PRIMARY) is not relevant to cgroup.

bpftool-cgroup should query just only cgroup-related attach types.

v2->v3:
  - removed an unnecessary check

v1->v2:
  - used an array of cgroup attach types

Signed-off-by: Kenta Tada <tadakentaso@gmail.com>
---
 tools/bpf/bpftool/cgroup.c | 40 ++++++++++++++++++++++++++++++++++----
 1 file changed, 36 insertions(+), 4 deletions(-)

diff --git a/tools/bpf/bpftool/cgroup.c b/tools/bpf/bpftool/cgroup.c
index af6898c0f388..9af426d43299 100644
--- a/tools/bpf/bpftool/cgroup.c
+++ b/tools/bpf/bpftool/cgroup.c
@@ -19,6 +19,38 @@
 
 #include "main.h"
 
+static const int cgroup_attach_types[] = {
+	BPF_CGROUP_INET_INGRESS,
+	BPF_CGROUP_INET_EGRESS,
+	BPF_CGROUP_INET_SOCK_CREATE,
+	BPF_CGROUP_INET_SOCK_RELEASE,
+	BPF_CGROUP_INET4_BIND,
+	BPF_CGROUP_INET6_BIND,
+	BPF_CGROUP_INET4_POST_BIND,
+	BPF_CGROUP_INET6_POST_BIND,
+	BPF_CGROUP_INET4_CONNECT,
+	BPF_CGROUP_INET6_CONNECT,
+	BPF_CGROUP_UNIX_CONNECT,
+	BPF_CGROUP_INET4_GETPEERNAME,
+	BPF_CGROUP_INET6_GETPEERNAME,
+	BPF_CGROUP_UNIX_GETPEERNAME,
+	BPF_CGROUP_INET4_GETSOCKNAME,
+	BPF_CGROUP_INET6_GETSOCKNAME,
+	BPF_CGROUP_UNIX_GETSOCKNAME,
+	BPF_CGROUP_UDP4_SENDMSG,
+	BPF_CGROUP_UDP6_SENDMSG,
+	BPF_CGROUP_UNIX_SENDMSG,
+	BPF_CGROUP_UDP4_RECVMSG,
+	BPF_CGROUP_UDP6_RECVMSG,
+	BPF_CGROUP_UNIX_RECVMSG,
+	BPF_CGROUP_SOCK_OPS,
+	BPF_CGROUP_DEVICE,
+	BPF_CGROUP_SYSCTL,
+	BPF_CGROUP_GETSOCKOPT,
+	BPF_CGROUP_SETSOCKOPT,
+	BPF_LSM_CGROUP
+};
+
 #define HELP_SPEC_ATTACH_FLAGS						\
 	"ATTACH_FLAGS := { multi | override }"
 
@@ -183,13 +215,13 @@ static int count_attached_bpf_progs(int cgroup_fd, enum bpf_attach_type type)
 
 static int cgroup_has_attached_progs(int cgroup_fd)
 {
-	enum bpf_attach_type type;
+	unsigned int i = 0;
 	bool no_prog = true;
 
-	for (type = 0; type < __MAX_BPF_ATTACH_TYPE; type++) {
-		int count = count_attached_bpf_progs(cgroup_fd, type);
+	for (i = 0; i < ARRAY_SIZE(cgroup_attach_types); i++) {
+		int count = count_attached_bpf_progs(cgroup_fd, cgroup_attach_types[i]);
 
-		if (count < 0 && errno != EINVAL)
+		if (count < 0)
 			return -1;
 
 		if (count > 0) {
-- 
2.43.0

Re: [PATCH v3] bpftool: Query only cgroup-related attach types

[Quentin Monnet]

2024-06-07 12:17 UTC+0100 ~ Kenta Tada <tadakentaso@gmail.com>
> When CONFIG_NETKIT=y,
> bpftool-cgroup shows error even if the cgroup's path is correct:
> 
> $ bpftool cgroup tree /sys/fs/cgroup
> CgroupPath
> ID       AttachType      AttachFlags     Name
> Error: can't query bpf programs attached to /sys/fs/cgroup: No such device or address
> 
> From strace and kernel tracing, I found netkit returned ENXIO and this command failed.
> I think this AttachType(BPF_NETKIT_PRIMARY) is not relevant to cgroup.
> 
> bpftool-cgroup should query just only cgroup-related attach types.
> 
> v2->v3:
>   - removed an unnecessary check
> 
> v1->v2:
>   - used an array of cgroup attach types
> 
> Signed-off-by: Kenta Tada <tadakentaso@gmail.com>


Reviewed-by: Quentin Monnet <qmo@kernel.org>

Thanks!

Re: [PATCH v3] bpftool: Query only cgroup-related attach types

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to bpf/bpf-next.git (master)
by Alexei Starovoitov <ast@kernel.org>:

On Fri,  7 Jun 2024 20:17:04 +0900 you wrote:
> When CONFIG_NETKIT=y,
> bpftool-cgroup shows error even if the cgroup's path is correct:
> 
> $ bpftool cgroup tree /sys/fs/cgroup
> CgroupPath
> ID       AttachType      AttachFlags     Name
> Error: can't query bpf programs attached to /sys/fs/cgroup: No such device or address
> 
> [...]

Here is the summary with links:
  - [v3] bpftool: Query only cgroup-related attach types
    https://git.kernel.org/bpf/bpf-next/c/98b303c9bf05

You are awesome, thank you!
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