setrlimit() and 2.4.0-test11

setrlimit() and 2.4.0-test11

[Arkadiusz Miskiewicz]

Is probably broken (I didnt't saw any disscusion about this here,
I missed it?).

when I try to start first user process I get:
4366  fork()                            = -1 EAGAIN (Resource temporarily unavailable)
but strace show proper value passed to setrlimit() -- 40 max number of processes:
4366  setrlimit(0x6 /* RLIMIT_??? */, {rlim_cur=40, rlim_max=40}) = 0

On test10 everything is ok.

This change broke test11 ?

diff -u --recursive --new-file v2.4.0-test10/linux/fs/proc/array.c linux/fs/proc/array.c
--- v2.4.0-test10/linux/fs/proc/array.c Tue Oct 31 12:42:27 2000
+++ linux/fs/proc/array.c       Tue Nov 14 11:22:36 2000
@@ -372,7 +372,7 @@
                task->start_time,
                vsize,
                mm ? mm->rss : 0, /* you might want to shift this left 3 */
-               task->rlim ? task->rlim[RLIMIT_RSS].rlim_cur : 0,
+               task->rlim[RLIMIT_RSS].rlim_cur,
                mm ? mm->start_code : 0,
                mm ? mm->end_code : 0,
                mm ? mm->start_stack : 0,

I need patch.

-- 
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Re: setrlimit() and 2.4.0-test11

[Jan Rekorajski]

On Wed, 22 Nov 2000, Arkadiusz Miskiewicz wrote:

> 
> Is probably broken (I didnt't saw any disscusion about this here,
> I missed it?).
> 
> when I try to start first user process I get:
> 4366  fork()                            = -1 EAGAIN (Resource temporarily unavailable)
> but strace show proper value passed to setrlimit() -- 40 max number of processes:
> 4366  setrlimit(0x6 /* RLIMIT_??? */, {rlim_cur=40, rlim_max=40}) = 0
> 
> On test10 everything is ok.

No, you are just lucky.
The problem is that root (uid=0) is not a special case anymore, and you can't
do something like this:

setrlimit(NPROC)
fork()
setuid(user)

setrlimit() and fork() are executed in root context, so sterlimit
apllies to root, not the user you're setuid to :(

Why is this so? root should be able to do fork() regardless of any limits,
and IMHO the following patch is the right thing.

--- linux/kernel/fork.c~	Tue Sep  5 23:48:59 2000
+++ linux/kernel/fork.c	Sun Nov 26 20:22:20 2000
@@ -560,7 +560,8 @@
 	*p = *current;
 
 	retval = -EAGAIN;
-	if (atomic_read(&p->user->processes) >= p->rlim[RLIMIT_NPROC].rlim_cur)
+	if (p->user->uid &&
+	   (atomic_read(&p->user->processes) >= p->rlim[RLIMIT_NPROC].rlim_cur))
 		goto bad_fork_free;
 	atomic_inc(&p->user->__count);
 	atomic_inc(&p->user->processes);

Jan
-- 
Jan Rękorajski            |  ALL SUSPECTS ARE GUILTY. PERIOD!
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