diff options
| author | jamie <jamie@FreeBSD.org> | 2016-06-09 16:41:41 +0000 |
|---|---|---|
| committer | jamie <jamie@FreeBSD.org> | 2016-06-09 16:41:41 +0000 |
| commit | debe558799a039749c66e1bfa41c6d004cd4f0f6 (patch) | |
| tree | a41be9be1954b956558a81dc0727aadda327b5ac /sys/kern | |
| parent | d140ca2a4e21b6bb4289b965c6e05dc56c90e384 (diff) | |
| download | FreeBSD-src-debe558799a039749c66e1bfa41c6d004cd4f0f6.zip FreeBSD-src-debe558799a039749c66e1bfa41c6d004cd4f0f6.tar.gz | |
Make sure the OSD methods for jail set and remove can't run concurrently,
by holding allprison_lock exclusively (even if only for a moment before
downgrading) on all paths that call PR_METHOD_REMOVE. Since they may run
on a downgraded lock, it's still possible for them to run concurrently
with PR_METHOD_GET, which will need to use the prison lock.
Diffstat (limited to 'sys/kern')
| -rw-r--r-- | sys/kern/kern_jail.c | 22 |
1 files changed, 13 insertions, 9 deletions
diff --git a/sys/kern/kern_jail.c b/sys/kern/kern_jail.c index 35e270a..ea4b628 100644 --- a/sys/kern/kern_jail.c +++ b/sys/kern/kern_jail.c @@ -2383,7 +2383,14 @@ sys_jail_attach(struct thread *td, struct jail_attach_args *uap) if (error) return (error); - sx_slock(&allprison_lock); + /* + * Start with exclusive hold on allprison_lock to ensure that a possible + * PR_METHOD_REMOVE call isn't concurrent with jail_set or jail_remove. + * But then immediately downgrade it since we don't need to stop + * readers. + */ + sx_xlock(&allprison_lock); + sx_downgrade(&allprison_lock); pr = prison_find_child(td->td_ucred->cr_prison, uap->jid); if (pr == NULL) { sx_sunlock(&allprison_lock); @@ -2601,9 +2608,11 @@ prison_complete(void *context, int pending) { struct prison *pr = context; + sx_xlock(&allprison_lock); mtx_lock(&pr->pr_mtx); prison_deref(pr, pr->pr_uref - ? PD_DEREF | PD_DEUREF | PD_LOCKED : PD_LOCKED); + ? PD_DEREF | PD_DEUREF | PD_LOCKED | PD_LIST_XLOCKED + : PD_LOCKED | PD_LIST_XLOCKED); } /* @@ -2647,13 +2656,8 @@ prison_deref(struct prison *pr, int flags) */ if (lasturef) { if (!(flags & (PD_LIST_SLOCKED | PD_LIST_XLOCKED))) { - if (ref > 1) { - sx_slock(&allprison_lock); - flags |= PD_LIST_SLOCKED; - } else { - sx_xlock(&allprison_lock); - flags |= PD_LIST_XLOCKED; - } + sx_xlock(&allprison_lock); + flags |= PD_LIST_XLOCKED; } (void)osd_jail_call(pr, PR_METHOD_REMOVE, NULL); mtx_lock(&pr->pr_mtx); |
