diff options
| author | Oleg Nesterov <oleg@redhat.com> | 2009-09-03 19:21:45 +0200 |
|---|---|---|
| committer | Jiri Slaby <jirislaby@gmail.com> | 2010-07-16 09:48:46 +0200 |
| commit | 2fb9d2689a0041b88b25bc3187eada2968e25995 (patch) | |
| tree | 28c25b5092a209cd55d5d3f29dea827bdde70abe /kernel/sys.c | |
| parent | 5ab46b345e418747b3a52f0892680c0745c4223c (diff) | |
| download | lwn-2fb9d2689a0041b88b25bc3187eada2968e25995.tar.gz lwn-2fb9d2689a0041b88b25bc3187eada2968e25995.zip | |
rlimits: make sure ->rlim_max never grows in sys_setrlimit
Mostly preparation for Jiri's changes, but probably makes sense anyway.
sys_setrlimit() checks new_rlim.rlim_max <= old_rlim->rlim_max, but when
it takes task_lock() old_rlim->rlim_max can be already lowered. Move this
check under task_lock().
Currently this is not important, we can only race with our sub-thread,
this means the application is stupid. But when we change the code to allow
the update of !current task's limits, it becomes important to make sure
->rlim_max can be lowered "reliably" even if we race with the application
doing sys_setrlimit().
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Diffstat (limited to 'kernel/sys.c')
| -rw-r--r-- | kernel/sys.c | 15 |
1 files changed, 8 insertions, 7 deletions
diff --git a/kernel/sys.c b/kernel/sys.c index f5183b08adfc..f2b2d7aa3818 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -1283,10 +1283,6 @@ SYSCALL_DEFINE2(setrlimit, unsigned int, resource, struct rlimit __user *, rlim) return -EFAULT; if (new_rlim.rlim_cur > new_rlim.rlim_max) return -EINVAL; - old_rlim = current->signal->rlim + resource; - if ((new_rlim.rlim_max > old_rlim->rlim_max) && - !capable(CAP_SYS_RESOURCE)) - return -EPERM; if (resource == RLIMIT_NOFILE && new_rlim.rlim_max > sysctl_nr_open) return -EPERM; @@ -1304,11 +1300,16 @@ SYSCALL_DEFINE2(setrlimit, unsigned int, resource, struct rlimit __user *, rlim) new_rlim.rlim_cur = 1; } + old_rlim = current->signal->rlim + resource; task_lock(current->group_leader); - *old_rlim = new_rlim; + if (new_rlim.rlim_max > old_rlim->rlim_max && + !capable(CAP_SYS_RESOURCE)) + retval = -EPERM; + else + *old_rlim = new_rlim; task_unlock(current->group_leader); - if (resource != RLIMIT_CPU) + if (retval || resource != RLIMIT_CPU) goto out; /* @@ -1322,7 +1323,7 @@ SYSCALL_DEFINE2(setrlimit, unsigned int, resource, struct rlimit __user *, rlim) update_rlimit_cpu(current, new_rlim.rlim_cur); out: - return 0; + return retval; } /* |