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fork: bump process count before checking for permission to cross the limit

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The limit is almost never reached. Do the check only on failure to see if
we can override it.

No change in user-visible behavior.

Sponsored by:	The FreeBSD Foundation
This commit is contained in:
Mateusz Guzik 2019-08-17 17:56:43 +00:00
parent b05641b6bd
commit 60cdcb644d
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=351174
1 changed files with 10 additions and 13 deletions
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23
sys/kern/kern_fork.c
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@ -800,9 +800,10 @@ fork1(struct thread *td, struct fork_req *fr)
struct proc *p1, *newproc;
struct thread *td2;
struct vmspace *vm2;
struct ucred *cred;
struct file *fp_procdesc;
vm_ooffset_t mem_charged;
int error, nprocs_new, ok;
int error, nprocs_new;
static int curfail;
static struct timeval lastfail;
int flags, pages;
@ -973,21 +974,17 @@ fork1(struct thread *td, struct fork_req *fr)
/*
* Increment the count of procs running with this uid. Don't allow
* a nonprivileged user to exceed their current limit.
*
* XXXRW: Can we avoid privilege here if it's not needed?
*/
error = priv_check_cred(td->td_ucred, PRIV_PROC_LIMIT);
if (error == 0)
ok = chgproccnt(td->td_ucred->cr_ruidinfo, 1, 0);
else {
ok = chgproccnt(td->td_ucred->cr_ruidinfo, 1,
lim_cur(td, RLIMIT_NPROC));
}
if (ok) {
do_fork(td, fr, newproc, td2, vm2, fp_procdesc);
return (0);
cred = td->td_ucred;
if (!chgproccnt(cred->cr_ruidinfo, 1, lim_cur(td, RLIMIT_NPROC))) {
if (priv_check_cred(cred, PRIV_PROC_LIMIT) != 0)
goto fail0;
chgproccnt(cred->cr_ruidinfo, 1, 0);
}
do_fork(td, fr, newproc, td2, vm2, fp_procdesc);
return (0);
fail0:
error = EAGAIN;
sx_xunlock(&allproc_lock);
#ifdef MAC