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sched: don't allow setuid to succeed if the user does not have rt bandwidth

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Impact: fix hung task with certain (non-default) rt-limit settings

Corey Hickey reported that on using setuid to change the uid of a
rt process, the process would be unkillable and not be running.
This is because there was no rt runtime for that user group. Add
in a check to see if a user can attach an rt task to its task group.
On failure, return EINVAL, which is also returned in
CONFIG_CGROUP_SCHED.

Reported-by: Corey Hickey <bugfood-ml@fatooh.org>
Signed-off-by: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Dhaval Giani
2009-02-27 15:13:54 +05:30
committed by Ingo Molnar
parent cac64d00c2
commit 54e9912428
4 changed files with 53 additions and 13 deletions
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31
kernel/sys.c
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@@ -559,7 +559,7 @@ error:
abort_creds(new);
return retval;
}
/*
* change the user struct in a credentials set to match the new UID
*/
@@ -571,6 +571,11 @@ static int set_user(struct cred *new)
if (!new_user)
return -EAGAIN;
if (!task_can_switch_user(new_user, current)) {
free_uid(new_user);
return -EINVAL;
}
if (atomic_read(&new_user->processes) >=
current->signal->rlim[RLIMIT_NPROC].rlim_cur &&
new_user != INIT_USER) {
@@ -631,10 +636,11 @@ SYSCALL_DEFINE2(setreuid, uid_t, ruid, uid_t, euid)
goto error;
}
retval = -EAGAIN;
if (new->uid != old->uid && set_user(new) < 0)
goto error;
if (new->uid != old->uid) {
retval = set_user(new);
if (retval < 0)
goto error;
}
if (ruid != (uid_t) -1 ||
(euid != (uid_t) -1 && euid != old->uid))
new->suid = new->euid;
@@ -680,9 +686,10 @@ SYSCALL_DEFINE1(setuid, uid_t, uid)
retval = -EPERM;
if (capable(CAP_SETUID)) {
new->suid = new->uid = uid;
if (uid != old->uid && set_user(new) < 0) {
retval = -EAGAIN;
goto error;
if (uid != old->uid) {
retval = set_user(new);
if (retval < 0)
goto error;
}
} else if (uid != old->uid && uid != new->suid) {
goto error;
@@ -734,11 +741,13 @@ SYSCALL_DEFINE3(setresuid, uid_t, ruid, uid_t, euid, uid_t, suid)
goto error;
}
retval = -EAGAIN;
if (ruid != (uid_t) -1) {
new->uid = ruid;
if (ruid != old->uid && set_user(new) < 0)
goto error;
if (ruid != old->uid) {
retval = set_user(new);
if (retval < 0)
goto error;
}
}
if (euid != (uid_t) -1)
new->euid = euid;