diff options
| author | Eric W. Biederman <ebiederm@xmission.com> | 2022-01-20 11:04:01 -0600 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-02-11 08:41:17 +0100 |
| commit | 7e33a0ad792f04bad920c7197bda8cc2ea08d304 (patch) | |
| tree | 61be69cfb042cea68c05cbedc1344e29fcc73992 /kernel | |
| parent | 7a66c048082c95969f767ee6a9b31c85f5b35edf (diff) | |
| download | linux-stable-7e33a0ad792f04bad920c7197bda8cc2ea08d304.tar.gz linux-stable-7e33a0ad792f04bad920c7197bda8cc2ea08d304.tar.bz2 linux-stable-7e33a0ad792f04bad920c7197bda8cc2ea08d304.zip | |
cgroup-v1: Require capabilities to set release_agent
commit 24f6008564183aa120d07c03d9289519c2fe02af upstream.
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>
[mkoutny: Adjust for pre-fs_context, duplicate mount/remount check, drop log messages.]
Acked-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/cgroup.c | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 248b0bf5d679..5702419c9f30 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -1854,6 +1854,7 @@ static int cgroup_remount(struct kernfs_root *kf_root, int *flags, char *data) { int ret = 0; struct cgroup_root *root = cgroup_root_from_kf(kf_root); + struct cgroup_namespace *ns = current->nsproxy->cgroup_ns; struct cgroup_sb_opts opts; u16 added_mask, removed_mask; @@ -1873,6 +1874,13 @@ static int cgroup_remount(struct kernfs_root *kf_root, int *flags, char *data) pr_warn("option changes via remount are deprecated (pid=%d comm=%s)\n", task_tgid_nr(current), current->comm); + /* See cgroup_mount release_agent handling */ + if (opts.release_agent && + ((ns->user_ns != &init_user_ns) || !capable(CAP_SYS_ADMIN))) { + ret = -EINVAL; + goto out_unlock; + } + added_mask = opts.subsys_mask & ~root->subsys_mask; removed_mask = root->subsys_mask & ~opts.subsys_mask; @@ -2248,6 +2256,16 @@ static struct dentry *cgroup_mount(struct file_system_type *fs_type, goto out_unlock; } + /* + * Release agent gets called with all capabilities, + * require capabilities to set release agent. + */ + if (opts.release_agent && + ((ns->user_ns != &init_user_ns) || !capable(CAP_SYS_ADMIN))) { + ret = -EINVAL; + goto out_unlock; + } + root = kzalloc(sizeof(*root), GFP_KERNEL); if (!root) { ret = -ENOMEM; @@ -3026,6 +3044,14 @@ 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; |