From 5038d42d2e60c855cf5b097197d95adaa1269d32 Mon Sep 17 00:00:00 2001 From: San Mehat Date: Thu, 21 May 2009 14:10:06 -0700 Subject: [PATCH] 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 'can_attach' handler, then we fall back to doing our checks the old way. This way non-root processes can add arbitrary processes to a cgroup if all the registered subsystems on that cgroup agree. Also change explicit euid == 0 check to CAP_SYS_ADMIN Signed-off-by: San Mehat --- kernel/cgroup.c | 19 ++++++++++--------- kernel/cgroup_freezer.c | 8 ++++++++ kernel/cpuset.c | 7 +++++++ kernel/sched.c | 9 +++++++++ 4 files changed, 34 insertions(+), 9 deletions(-) diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 0249f4be9b5c..455689fd1971 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -51,6 +51,7 @@ #include #include #include /* TODO: replace with more sophisticated array */ +#include #include @@ -1555,6 +1556,15 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk) retval = ss->can_attach(ss, cgrp, tsk, false); if (retval) return retval; + } else if (!capable(CAP_SYS_ADMIN)) { + const struct cred *cred = current_cred(), *tcred; + + /* No can_attach() - check perms generically */ + tcred = __task_cred(tsk); + if (cred->euid != tcred->uid && + cred->euid != tcred->suid) { + return -EACCES; + } } } @@ -1611,7 +1621,6 @@ int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk) static int attach_task_by_pid(struct cgroup *cgrp, u64 pid) { struct task_struct *tsk; - const struct cred *cred = current_cred(), *tcred; int ret; if (pid) { @@ -1621,14 +1630,6 @@ static int attach_task_by_pid(struct cgroup *cgrp, u64 pid) rcu_read_unlock(); return -ESRCH; } - - tcred = __task_cred(tsk); - if (cred->euid && - cred->euid != tcred->uid && - cred->euid != tcred->suid) { - rcu_read_unlock(); - return -EACCES; - } get_task_struct(tsk); rcu_read_unlock(); } else { diff --git a/kernel/cgroup_freezer.c b/kernel/cgroup_freezer.c index 59e9ef6aab40..67b155f65a6c 100644 --- a/kernel/cgroup_freezer.c +++ b/kernel/cgroup_freezer.c @@ -163,6 +163,14 @@ static int freezer_can_attach(struct cgroup_subsys *ss, { struct freezer *freezer; + if ((current != task) && (!capable(CAP_SYS_ADMIN))) { + const struct cred *cred = current_cred(), *tcred; + + tcred = __task_cred(task); + if (cred->euid != tcred->uid && cred->euid != tcred->suid) + return -EPERM; + } + /* * Anything frozen can't move or be moved to/from. * diff --git a/kernel/cpuset.c b/kernel/cpuset.c index b5cb469d2545..2b637ca37be4 100644 --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -1330,6 +1330,13 @@ static int cpuset_can_attach(struct cgroup_subsys *ss, struct cgroup *cont, int ret; struct cpuset *cs = cgroup_cs(cont); + if ((current != task) && (!capable(CAP_SYS_ADMIN))) { + const struct cred *cred = current_cred(), *tcred; + + if (cred->euid != tcred->uid && cred->euid != tcred->suid) + return -EPERM; + } + if (cpumask_empty(cs->cpus_allowed) || nodes_empty(cs->mems_allowed)) return -ENOSPC; diff --git a/kernel/sched.c b/kernel/sched.c index 9f11c6c78415..117b2b4ebbaf 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -10418,6 +10418,15 @@ cpu_cgroup_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp) static int cpu_cgroup_can_attach_task(struct cgroup *cgrp, struct task_struct *tsk) { + if ((current != tsk) && (!capable(CAP_SYS_NICE))) { + const struct cred *cred = current_cred(), *tcred; + + tcred = __task_cred(tsk); + + if (cred->euid != tcred->uid && cred->euid != tcred->suid) + return -EPERM; + } + #ifdef CONFIG_RT_GROUP_SCHED if (!sched_rt_can_attach(cgroup_tg(cgrp), tsk)) return -EINVAL; -- 2.34.1