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Subject[PATCH 06/11] rlimits: do security check under task_lock
Date
Do security_task_setrlimit under task_lock. Other tasks may
change limits under our hands while we are checking limits
inside the function. From now on, they can't.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: James Morris <jmorris@namei.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@elte.hu>
---
kernel/sys.c | 16 +++++++---------
1 files changed, 7 insertions(+), 9 deletions(-)
diff --git a/kernel/sys.c b/kernel/sys.c
index eb21661..9e9a3a7 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1277,7 +1277,7 @@ int do_setrlimit(struct task_struct *tsk, unsigned int resource,
struct rlimit *new_rlim)
{
struct rlimit *old_rlim;
- int retval;
+ int retval = 0;

if (resource >= RLIM_NLIMITS)
return -EINVAL;
@@ -1293,10 +1293,6 @@ int do_setrlimit(struct task_struct *tsk, unsigned int resource,
goto out;
}

- retval = security_task_setrlimit(tsk, resource, new_rlim);
- if (retval)
- goto out;
-
if (resource == RLIMIT_CPU && new_rlim->rlim_cur == 0) {
/*
* The caller is asking for an immediate RLIMIT_CPU
@@ -1309,11 +1305,13 @@ int do_setrlimit(struct task_struct *tsk, unsigned int resource,

old_rlim = tsk->signal->rlim + resource;
task_lock(tsk->group_leader);
- if ((new_rlim->rlim_max <= old_rlim->rlim_max) ||
- capable(CAP_SYS_RESOURCE))
- *old_rlim = *new_rlim;
- else
+ if ((new_rlim->rlim_max > old_rlim->rlim_max) &&
+ !capable(CAP_SYS_RESOURCE))
retval = -EPERM;
+ if (!retval)
+ retval = security_task_setrlimit(tsk, resource, new_rlim);
+ if (!retval)
+ *old_rlim = *new_rlim;
task_unlock(tsk->group_leader);

if (retval || resource != RLIMIT_CPU)
--
1.7.1



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