linux/security/selinux
Dave Jones 9a591f39a9 selinux: conditionally reschedule in mls_convert_context while loading selinux policy
On a slow machine (with debugging enabled), upgrading selinux policy may take
a considerable amount of time. Long enough that the softlockup detector
gets triggered.

The backtrace looks like this..

 > BUG: soft lockup - CPU#2 stuck for 23s! [load_policy:19045]
 > Call Trace:
 >  [<ffffffff81221ddf>] symcmp+0xf/0x20
 >  [<ffffffff81221c27>] hashtab_search+0x47/0x80
 >  [<ffffffff8122e96c>] mls_convert_context+0xdc/0x1c0
 >  [<ffffffff812294e8>] convert_context+0x378/0x460
 >  [<ffffffff81229170>] ? security_context_to_sid_core+0x240/0x240
 >  [<ffffffff812221b5>] sidtab_map+0x45/0x80
 >  [<ffffffff8122bb9f>] security_load_policy+0x3ff/0x580
 >  [<ffffffff810788a8>] ? sched_clock_cpu+0xa8/0x100
 >  [<ffffffff810786dd>] ? sched_clock_local+0x1d/0x80
 >  [<ffffffff810788a8>] ? sched_clock_cpu+0xa8/0x100
 >  [<ffffffff8103096a>] ? __change_page_attr_set_clr+0x82a/0xa50
 >  [<ffffffff810786dd>] ? sched_clock_local+0x1d/0x80
 >  [<ffffffff810788a8>] ? sched_clock_cpu+0xa8/0x100
 >  [<ffffffff8103096a>] ? __change_page_attr_set_clr+0x82a/0xa50
 >  [<ffffffff810788a8>] ? sched_clock_cpu+0xa8/0x100
 >  [<ffffffff81534ddc>] ? retint_restore_args+0xe/0xe
 >  [<ffffffff8109c82d>] ? trace_hardirqs_on_caller+0xfd/0x1c0
 >  [<ffffffff81279a2e>] ? trace_hardirqs_on_thunk+0x3a/0x3f
 >  [<ffffffff810d28a8>] ? rcu_irq_exit+0x68/0xb0
 >  [<ffffffff81534ddc>] ? retint_restore_args+0xe/0xe
 >  [<ffffffff8121e947>] sel_write_load+0xa7/0x770
 >  [<ffffffff81139633>] ? vfs_write+0x1c3/0x200
 >  [<ffffffff81210e8e>] ? security_file_permission+0x1e/0xa0
 >  [<ffffffff8113952b>] vfs_write+0xbb/0x200
 >  [<ffffffff811581c7>] ? fget_light+0x397/0x4b0
 >  [<ffffffff81139c27>] SyS_write+0x47/0xa0
 >  [<ffffffff8153bde4>] tracesys+0xdd/0xe2

Stephen Smalley suggested:

 > Maybe put a cond_resched() within the ebitmap_for_each_positive_bit()
 > loop in mls_convert_context()?

That seems to do the trick. Tested by downgrading and re-upgrading selinux-policy-targeted.

Signed-off-by: Dave Jones <davej@redhat.com>
Acked-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <pmoore@redhat.com>
2014-06-03 14:21:49 -05:00
..
include selinux: Report permissive mode in avc: denied messages. 2014-06-03 14:21:48 -05:00
ss selinux: conditionally reschedule in mls_convert_context while loading selinux policy 2014-06-03 14:21:49 -05:00
.gitignore
avc.c selinux: Report permissive mode in avc: denied messages. 2014-06-03 14:21:48 -05:00
exports.c
hooks.c selinux: reject setexeccon() on MNT_NOSUID applications with -EACCES 2014-06-03 14:21:48 -05:00
Kconfig
Makefile
netif.c net: pass info struct via netdevice notifier 2013-05-28 13:11:01 -07:00
netlabel.c selinux: ensure that the cached NetLabel secattr matches the desired SID 2013-12-04 16:08:17 -05:00
netlink.c selinux: replace obsolete NLMSG_* with type safe nlmsg_* 2013-03-28 14:25:49 -04:00
netnode.c selinux: fix problems in netnode when BUG() is compiled out 2013-07-25 13:03:27 -04:00
netport.c SELinux: avc: remove the useless fields in avc_add_callback 2012-04-09 12:23:44 -04:00
nlmsgtab.c selinux: add SOCK_DIAG_BY_FAMILY to the list of netlink message types 2014-02-05 12:20:48 -05:00
selinuxfs.c Merge commit 'v3.14' into next 2014-04-14 11:23:14 +10:00
xfrm.c selinux: add gfp argument to security_xfrm_policy_alloc and fix callers 2014-03-10 08:30:02 +01:00