LinuxLists.cc - [PATCH bpf v5 0/3] Fix wrong cgroup attach flags being assigned to effective progs

2022-09-21 02:53:16

Subject: [PATCH bpf v5 0/3] Fix wrong cgroup attach flags being assigned to effective progs

2022-09-21 02:53:40

Subject: [PATCH bpf v5 3/3] selftests/bpf: Adapt cgroup effective query uapi change

From: Pu Lehui <[email protected]>

The attach flags is meaningless for effective query and
its value will always be set as 0 during effective query.
Root cg's effective progs is always its attached progs,
so we use non-effective query to get its progs count and
attach flags. And we don't need the remain attach flags
check.

Fixes: b79c9fc9551b ("bpf: implement BPF_PROG_QUERY for BPF_LSM_CGROUP")
Signed-off-by: Pu Lehui <[email protected]>
---
tools/testing/selftests/bpf/prog_tests/cgroup_link.c | 11 ++++-------
1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/cgroup_link.c b/tools/testing/selftests/bpf/prog_tests/cgroup_link.c
index 9e6e6aad347c..15093a69510e 100644
--- a/tools/testing/selftests/bpf/prog_tests/cgroup_link.c
+++ b/tools/testing/selftests/bpf/prog_tests/cgroup_link.c
@@ -71,10 +71,9 @@ void serial_test_cgroup_link(void)

ping_and_check(cg_nr, 0);

- /* query the number of effective progs and attach flags in root cg */
+ /* query the number of attached progs and attach flags in root cg */
err = bpf_prog_query(cgs[0].fd, BPF_CGROUP_INET_EGRESS,
- BPF_F_QUERY_EFFECTIVE, &attach_flags, NULL,
- &prog_cnt);
+ 0, &attach_flags, NULL, &prog_cnt);
CHECK_FAIL(err);
CHECK_FAIL(attach_flags != BPF_F_ALLOW_MULTI);
if (CHECK(prog_cnt != 1, "effect_cnt", "exp %d, got %d\n", 1, prog_cnt))
@@ -85,17 +84,15 @@ void serial_test_cgroup_link(void)
BPF_F_QUERY_EFFECTIVE, NULL, NULL,
&prog_cnt);
CHECK_FAIL(err);
- CHECK_FAIL(attach_flags != BPF_F_ALLOW_MULTI);
if (CHECK(prog_cnt != cg_nr, "effect_cnt", "exp %d, got %d\n",
cg_nr, prog_cnt))
goto cleanup;

/* query the effective prog IDs in last cg */
err = bpf_prog_query(cgs[last_cg].fd, BPF_CGROUP_INET_EGRESS,
- BPF_F_QUERY_EFFECTIVE, &attach_flags,
- prog_ids, &prog_cnt);
+ BPF_F_QUERY_EFFECTIVE, NULL, prog_ids,
+ &prog_cnt);
CHECK_FAIL(err);
- CHECK_FAIL(attach_flags != BPF_F_ALLOW_MULTI);
if (CHECK(prog_cnt != cg_nr, "effect_cnt", "exp %d, got %d\n",
cg_nr, prog_cnt))
goto cleanup;
--
2.25.1

2022-09-21 02:53:56

by Pu Lehui

[permalink] [raw]

Subject: [PATCH bpf v5 2/3] bpftool: Fix wrong cgroup attach flags being assigned to effective progs

From: Pu Lehui <[email protected]>

When root-cgroup attach multi progs and sub-cgroup attach a override prog,
bpftool will display incorrectly for the attach flags of the sub-cgroup’s
effective progs:

$ bpftool cgroup tree /sys/fs/cgroup effective
CgroupPath
ID AttachType AttachFlags Name
/sys/fs/cgroup
6 cgroup_sysctl multi sysctl_tcp_mem
13 cgroup_sysctl multi sysctl_tcp_mem
/sys/fs/cgroup/cg1
20 cgroup_sysctl override sysctl_tcp_mem
6 cgroup_sysctl override sysctl_tcp_mem <- wrong
13 cgroup_sysctl override sysctl_tcp_mem <- wrong
/sys/fs/cgroup/cg1/cg2
20 cgroup_sysctl sysctl_tcp_mem
6 cgroup_sysctl sysctl_tcp_mem
13 cgroup_sysctl sysctl_tcp_mem

Attach flags is only valid for attached progs of this layer cgroup,
but not for effective progs. For querying with EFFECTIVE flags,
exporting attach flags does not make sense. So let's remove the
AttachFlags field and the associated logic. After this patch, the
above effective cgroup tree will show as bellow:

$ bpftool cgroup tree /sys/fs/cgroup effective
CgroupPath
ID AttachType Name
/sys/fs/cgroup
6 cgroup_sysctl sysctl_tcp_mem
13 cgroup_sysctl sysctl_tcp_mem
/sys/fs/cgroup/cg1
20 cgroup_sysctl sysctl_tcp_mem
6 cgroup_sysctl sysctl_tcp_mem
13 cgroup_sysctl sysctl_tcp_mem
/sys/fs/cgroup/cg1/cg2
20 cgroup_sysctl sysctl_tcp_mem
6 cgroup_sysctl sysctl_tcp_mem
13 cgroup_sysctl sysctl_tcp_mem

Fixes: b79c9fc9551b ("bpf: implement BPF_PROG_QUERY for BPF_LSM_CGROUP")
Fixes: a98bf57391a2 ("tools: bpftool: add support for reporting the effective cgroup progs")
Signed-off-by: Pu Lehui <[email protected]>
---
tools/bpf/bpftool/cgroup.c | 54 ++++++++++++++++++++++++++++++++++----
1 file changed, 49 insertions(+), 5 deletions(-)

diff --git a/tools/bpf/bpftool/cgroup.c b/tools/bpf/bpftool/cgroup.c
index cced668fb2a3..b46a998d8f8d 100644
--- a/tools/bpf/bpftool/cgroup.c
+++ b/tools/bpf/bpftool/cgroup.c
@@ -136,8 +136,8 @@ static int show_bpf_prog(int id, enum bpf_attach_type attach_type,
jsonw_string_field(json_wtr, "attach_type", attach_type_str);
else
jsonw_uint_field(json_wtr, "attach_type", attach_type);
- jsonw_string_field(json_wtr, "attach_flags",
- attach_flags_str);
+ if (!(query_flags & BPF_F_QUERY_EFFECTIVE))
+ jsonw_string_field(json_wtr, "attach_flags", attach_flags_str);
jsonw_string_field(json_wtr, "name", prog_name);
if (attach_btf_name)
jsonw_string_field(json_wtr, "attach_btf_name", attach_btf_name);
@@ -150,7 +150,10 @@ static int show_bpf_prog(int id, enum bpf_attach_type attach_type,
printf("%-15s", attach_type_str);
else
printf("type %-10u", attach_type);
- printf(" %-15s %-15s", attach_flags_str, prog_name);
+ if (query_flags & BPF_F_QUERY_EFFECTIVE)
+ printf(" %-15s", prog_name);
+ else
+ printf(" %-15s %-15s", attach_flags_str, prog_name);
if (attach_btf_name)
printf(" %-15s", attach_btf_name);
else if (info.attach_btf_id)
@@ -195,6 +198,32 @@ static int cgroup_has_attached_progs(int cgroup_fd)

return no_prog ? 0 : 1;
}
+
+static int show_effective_bpf_progs(int cgroup_fd, enum bpf_attach_type type,
+ int level)
+{
+ LIBBPF_OPTS(bpf_prog_query_opts, p);
+ __u32 prog_ids[1024] = {0};
+ __u32 iter;
+ int ret;
+
+ p.query_flags = query_flags;
+ p.prog_cnt = ARRAY_SIZE(prog_ids);
+ p.prog_ids = prog_ids;
+
+ ret = bpf_prog_query_opts(cgroup_fd, type, &p);
+ if (ret)
+ return ret;
+
+ if (p.prog_cnt == 0)
+ return 0;
+
+ for (iter = 0; iter < p.prog_cnt; iter++)
+ show_bpf_prog(prog_ids[iter], type, NULL, level);
+
+ return 0;
+}
+
static int show_attached_bpf_progs(int cgroup_fd, enum bpf_attach_type type,
int level)
{
@@ -245,6 +274,14 @@ static int show_attached_bpf_progs(int cgroup_fd, enum bpf_attach_type type,
return 0;
}

+static int show_bpf_progs(int cgroup_fd, enum bpf_attach_type type,
+ int level)
+{
+ return query_flags & BPF_F_QUERY_EFFECTIVE ?
+ show_effective_bpf_progs(cgroup_fd, type, level) :
+ show_attached_bpf_progs(cgroup_fd, type, level);
+}
+
static int do_show(int argc, char **argv)
{
enum bpf_attach_type type;
@@ -292,6 +329,8 @@ static int do_show(int argc, char **argv)

if (json_output)
jsonw_start_array(json_wtr);
+ else if (query_flags & BPF_F_QUERY_EFFECTIVE)
+ printf("%-8s %-15s %-15s\n", "ID", "AttachType", "Name");
else
printf("%-8s %-15s %-15s %-15s\n", "ID", "AttachType",
"AttachFlags", "Name");
@@ -304,7 +343,7 @@ static int do_show(int argc, char **argv)
* If we were able to get the show for at least one
* attach type, let's return 0.
*/
- if (show_attached_bpf_progs(cgroup_fd, type, 0) == 0)
+ if (show_bpf_progs(cgroup_fd, type, 0) == 0)
ret = 0;
}

@@ -362,7 +401,7 @@ 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_attached_bpf_progs(cgroup_fd, type, ftw->level);
+ show_bpf_progs(cgroup_fd, type, ftw->level);

if (errno == EINVAL)
/* Last attach type does not support query.
@@ -436,6 +475,11 @@ static int do_show_tree(int argc, char **argv)

if (json_output)
jsonw_start_array(json_wtr);
+ else if (query_flags & BPF_F_QUERY_EFFECTIVE)
+ printf("%s\n"
+ "%-8s %-15s %-15s\n",
+ "CgroupPath",
+ "ID", "AttachType", "Name");
else
printf("%s\n"
"%-8s %-15s %-15s %-15s\n",
--
2.25.1

2022-09-21 18:57:47

by patchwork-bot+netdevbpf

[permalink] [raw]

Subject: Re: [PATCH bpf v5 0/3] Fix wrong cgroup attach flags being assigned to effective progs

Hello:

This series was applied to bpf/bpf.git (master)
by Martin KaFai Lau <[email protected]>:

On Wed, 21 Sep 2022 10:46:01 +0000 you wrote:
> From: Pu Lehui <[email protected]>
>
> When root-cgroup attach multi progs and sub-cgroup attach a
> override prog, bpftool will display incorrectly for the attach
> flags of the sub-cgroup’s effective progs:
>
> $ bpftool cgroup tree /sys/fs/cgroup effective
> CgroupPath
> ID AttachType AttachFlags Name
> /sys/fs/cgroup
> 6 cgroup_sysctl multi sysctl_tcp_mem
> 13 cgroup_sysctl multi sysctl_tcp_mem
> /sys/fs/cgroup/cg1
> 20 cgroup_sysctl override sysctl_tcp_mem
> 6 cgroup_sysctl override sysctl_tcp_mem <- wrong
> 13 cgroup_sysctl override sysctl_tcp_mem <- wrong
> /sys/fs/cgroup/cg1/cg2
> 20 cgroup_sysctl sysctl_tcp_mem
> 6 cgroup_sysctl sysctl_tcp_mem
> 13 cgroup_sysctl sysctl_tcp_mem
>
> [...]

Here is the summary with links:
- [bpf,v5,1/3] bpf, cgroup: Reject prog_attach_flags array when effective query
https://git.kernel.org/bpf/bpf/c/0e426a3ae030
- [bpf,v5,2/3] bpftool: Fix wrong cgroup attach flags being assigned to effective progs
https://git.kernel.org/bpf/bpf/c/bdcee1b0b083
- [bpf,v5,3/3] selftests/bpf: Adapt cgroup effective query uapi change
https://git.kernel.org/bpf/bpf/c/d2aa993b7d9d

You are awesome, thank you!
--
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html