diff options
| author | Colin Cross <ccross@android.com> | 2011-10-09 02:29:12 +0100 |
|---|---|---|
| committer | Andy Green <andy.green@linaro.org> | 2011-10-09 02:29:12 +0100 |
| commit | 5d322a8956226296e2d417451d0e32d57b52f0c7 (patch) | |
| tree | c917bb55244ff444d6572665726f7b8ba3116e6d /kernel | |
| parent | cd121310bfdf7075f959710a970efd99649be2b4 (diff) | |
cgroup: Add generic cgroup subsystem permission checks
Rather than using explicit euid == 0 checks when trying to move
tasks into a cgroup via CFS, move permission checks into each
specific cgroup subsystem. If a subsystem does not specify a
'allow_attach' handler, then we fall back to doing our checks
the old way.
Use the 'allow_attach' handler for the 'cpu' cgroup to allow
non-root processes to add arbitrary processes to a 'cpu' cgroup
if it has the CAP_SYS_NICE capability set.
This version of the patch adds a 'allow_attach' handler instead
of reusing the 'can_attach' handler. If the 'can_attach' handler
is reused, a new cgroup that implements 'can_attach' but not
the permission checks could end up with no permission checks
at all.
Change-Id: Icfa950aa9321d1ceba362061d32dc7dfa2c64f0c
Original-Author: San Mehat <san@google.com>
Signed-off-by: Colin Cross <ccross@android.com>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/cgroup.c | 31 | ||||
| -rw-r--r-- | kernel/sched.c | 15 |
2 files changed, 43 insertions, 3 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 84dd3818633..bab5a7911b8 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -2202,6 +2202,24 @@ out_free_group_list: return retval; } +static int cgroup_allow_attach(struct cgroup *cgrp, struct task_struct *tsk) +{ + struct cgroup_subsys *ss; + int ret; + + for_each_subsys(cgrp->root, ss) { + if (ss->allow_attach) { + ret = ss->allow_attach(cgrp, tsk); + if (ret) + return ret; + } else { + return -EACCES; + } + } + + return 0; +} + /* * Find the task_struct of the task to attach by vpid and pass it along to the * function to attach either it or all tasks in its threadgroup. Will take @@ -2247,9 +2265,16 @@ static int attach_task_by_pid(struct cgroup *cgrp, u64 pid, bool threadgroup) if (cred->euid && cred->euid != tcred->uid && cred->euid != tcred->suid) { - rcu_read_unlock(); - cgroup_unlock(); - return -EACCES; + /* + * if the default permission check fails, give each + * cgroup a chance to extend the permission check + */ + ret = cgroup_allow_attach(cgrp, tsk); + if (ret) { + rcu_read_unlock(); + cgroup_unlock(); + return ret; + } } get_task_struct(tsk); rcu_read_unlock(); diff --git a/kernel/sched.c b/kernel/sched.c index 7de220e79df..e7ec90424de 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -8966,6 +8966,20 @@ cpu_cgroup_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp) } static int +cpu_cgroup_allow_attach(struct cgroup *cgrp, struct task_struct *tsk) +{ + const struct cred *cred = current_cred(), *tcred; + + tcred = __task_cred(tsk); + + if ((current != tsk) && !capable(CAP_SYS_NICE) && + cred->euid != tcred->uid && cred->euid != tcred->suid) + return -EACCES; + + return 0; +} + +static int cpu_cgroup_can_attach_task(struct cgroup *cgrp, struct task_struct *tsk) { #ifdef CONFIG_RT_GROUP_SCHED @@ -9070,6 +9084,7 @@ struct cgroup_subsys cpu_cgroup_subsys = { .name = "cpu", .create = cpu_cgroup_create, .destroy = cpu_cgroup_destroy, + .allow_attach = cpu_cgroup_allow_attach, .can_attach_task = cpu_cgroup_can_attach_task, .attach_task = cpu_cgroup_attach_task, .exit = cpu_cgroup_exit, |