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| author | Eric W. Biederman <ebiederm@xmission.com> | 2022-01-20 11:04:01 -0600 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2022-02-01 07:28:00 -1000 |
| commit | 24f6008564183aa120d07c03d9289519c2fe02af (patch) | |
| tree | 116de0e1cf8b69ec7bdc1fec15a9a623d77eee04 /kernel/cgroup/cgroup-v1.c | |
| parent | c80d401c52a2d1baf2a5afeb06f0ffe678e56d23 (diff) | |
| download | lwn-24f6008564183aa120d07c03d9289519c2fe02af.tar.gz lwn-24f6008564183aa120d07c03d9289519c2fe02af.zip | |
cgroup-v1: Require capabilities to set release_agent
The cgroup release_agent is called with call_usermodehelper. The function
call_usermodehelper starts the release_agent with a full set fo capabilities.
Therefore require capabilities when setting the release_agaent.
Reported-by: Tabitha Sable <tabitha.c.sable@gmail.com>
Tested-by: Tabitha Sable <tabitha.c.sable@gmail.com>
Fixes: 81a6a5cdd2c5 ("Task Control Groups: automatic userspace notification of idle cgroups")
Cc: stable@vger.kernel.org # v2.6.24+
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'kernel/cgroup/cgroup-v1.c')
| -rw-r--r-- | kernel/cgroup/cgroup-v1.c | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c index 41e0837a5a0b..0e877dbcfeea 100644 --- a/kernel/cgroup/cgroup-v1.c +++ b/kernel/cgroup/cgroup-v1.c @@ -549,6 +549,14 @@ static ssize_t cgroup_release_agent_write(struct kernfs_open_file *of, BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX); + /* + * Release agent gets called with all capabilities, + * require capabilities to set release agent. + */ + if ((of->file->f_cred->user_ns != &init_user_ns) || + !capable(CAP_SYS_ADMIN)) + return -EPERM; + cgrp = cgroup_kn_lock_live(of->kn, false); if (!cgrp) return -ENODEV; @@ -954,6 +962,12 @@ int cgroup1_parse_param(struct fs_context *fc, struct fs_parameter *param) /* Specifying two release agents is forbidden */ if (ctx->release_agent) return invalfc(fc, "release_agent respecified"); + /* + * Release agent gets called with all capabilities, + * require capabilities to set release agent. + */ + if ((fc->user_ns != &init_user_ns) || !capable(CAP_SYS_ADMIN)) + return invalfc(fc, "Setting release_agent not allowed"); ctx->release_agent = param->string; param->string = NULL; break; |