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| author | Jiri Slaby <jirislaby@gmail.com> | 2009-08-28 14:08:17 +0200 |
|---|---|---|
| committer | Jiri Slaby <jirislaby@gmail.com> | 2010-07-16 09:48:47 +0200 |
| commit | 1c1e618ddd15f69fd87ccea596769f78c8065504 (patch) | |
| tree | f6b72aa3e0f1d02728d98810afc1644a1d6f5b8c | |
| parent | 7855c35da7ba16b389d17710401c4a55a3ea2102 (diff) | |
| download | linux-1c1e618ddd15f69fd87ccea596769f78c8065504.tar.gz linux-1c1e618ddd15f69fd87ccea596769f78c8065504.tar.bz2 linux-1c1e618ddd15f69fd87ccea596769f78c8065504.zip | |
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>
| -rw-r--r-- | kernel/sys.c | 11 |
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; } |