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authorJiri Slaby <jirislaby@gmail.com>2009-08-28 14:08:17 +0200
committerJiri Slaby <jirislaby@gmail.com>2010-07-16 09:48:47 +0200
commit1c1e618ddd15f69fd87ccea596769f78c8065504 (patch)
treef6b72aa3e0f1d02728d98810afc1644a1d6f5b8c /kernel
parent7855c35da7ba16b389d17710401c4a55a3ea2102 (diff)
rlimits: allow setrlimit to non-current tasks
Add locking to allow setrlimit accept task parameter other than current. Namely, lock tasklist_lock for read and check whether the task structure has sighand non-null. Do all the signal processing under that lock still held. There are some points: 1) security_task_setrlimit is now called with that lock held. This is not new, many security_* functions are called with this lock held already so it doesn't harm (all this security_* stuff does almost the same). 2) task->sighand->siglock (in update_rlimit_cpu) is nested in tasklist_lock. This dependence is already existing. 3) tsk->alloc_lock is nested in tasklist_lock. This is OK too, already existing dependence. Signed-off-by: Jiri Slaby <jirislaby@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sys.c11
1 files changed, 10 insertions, 1 deletions
diff --git a/kernel/sys.c b/kernel/sys.c
index b5b96e30e0d6..9dbcbbcce153 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1272,6 +1272,7 @@ SYSCALL_DEFINE2(old_getrlimit, unsigned int, resource,
#endif
+/* make sure you are allowed to change @tsk limits before calling this */
int do_setrlimit(struct task_struct *tsk, unsigned int resource,
struct rlimit *new_rlim)
{
@@ -1285,9 +1286,16 @@ int do_setrlimit(struct task_struct *tsk, unsigned int resource,
if (resource == RLIMIT_NOFILE && new_rlim->rlim_max > sysctl_nr_open)
return -EPERM;
+ /* protect tsk->signal and tsk->sighand from disappearing */
+ read_lock(&tasklist_lock);
+ if (!tsk->sighand) {
+ retval = -ESRCH;
+ goto out;
+ }
+
retval = security_task_setrlimit(tsk->group_leader, resource, new_rlim);
if (retval)
- return retval;
+ goto out;
if (resource == RLIMIT_CPU && new_rlim->rlim_cur == 0) {
/*
@@ -1322,6 +1330,7 @@ int do_setrlimit(struct task_struct *tsk, unsigned int resource,
update_rlimit_cpu(tsk, new_rlim->rlim_cur);
out:
+ read_unlock(&tasklist_lock);
return retval;
}