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| author | Michal Koutný <mkoutny@suse.com> | 2022-02-17 17:11:28 +0100 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2022-02-22 19:12:22 +0100 |
| commit | 467a726b754f474936980da793b4ff2ec3e382a7 (patch) | |
| tree | 00d3a89a6a4611e171e8122095861e9f77259ebf /kernel | |
| parent | cgroup: clarify cgroup_css_set_fork() (diff) | |
| download | linux-467a726b754f474936980da793b4ff2ec3e382a7.tar.xz linux-467a726b754f474936980da793b4ff2ec3e382a7.zip | |
cgroup-v1: Correct privileges check in release_agent writes
The idea is to check: a) the owning user_ns of cgroup_ns, b)
capabilities in init_user_ns.
The commit 24f600856418 ("cgroup-v1: Require capabilities to set
release_agent") got this wrong in the write handler of release_agent
since it checked user_ns of the opener (may be different from the owning
user_ns of cgroup_ns).
Secondly, to avoid possibly confused deputy, the capability of the
opener must be checked.
Fixes: 24f600856418 ("cgroup-v1: Require capabilities to set release_agent")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/stable/20220216121142.GB30035@blackbody.suse.cz/
Signed-off-by: Michal Koutný <mkoutny@suse.com>
Reviewed-by: Masami Ichikawa(CIP) <masami.ichikawa@cybertrust.co.jp>
Signed-off-by: Tejun Heo <tj@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/cgroup/cgroup-v1.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c index 0e877dbcfeea..afc6c0e9c966 100644 --- a/kernel/cgroup/cgroup-v1.c +++ b/kernel/cgroup/cgroup-v1.c @@ -546,6 +546,7 @@ static ssize_t cgroup_release_agent_write(struct kernfs_open_file *of, char *buf, size_t nbytes, loff_t off) { struct cgroup *cgrp; + struct cgroup_file_ctx *ctx; BUILD_BUG_ON(sizeof(cgrp->root->release_agent_path) < PATH_MAX); @@ -553,8 +554,9 @@ static ssize_t cgroup_release_agent_write(struct kernfs_open_file *of, * 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)) + ctx = of->priv; + if ((ctx->ns->user_ns != &init_user_ns) || + !file_ns_capable(of->file, &init_user_ns, CAP_SYS_ADMIN)) return -EPERM; cgrp = cgroup_kn_lock_live(of->kn, false); |