Messages in this thread Patch in this message | | | Date | Wed, 06 Feb 2013 11:28:34 -0500 | From | Stephen Smalley <> | Subject | Re: selinux_msg_queue_msgrcv() oops |
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On 02/06/2013 10:21 AM, Tommi Rantala wrote: > 2013/2/6 Stephen Smalley <sds@tycho.nsa.gov>: >> On 02/06/2013 07:56 AM, Tommi Rantala wrote: >>> >>> Hello, >>> >>> I'm hitting an oops in selinux_msg_queue_msgrcv() when fuzzing with >>> Trinity as the root user (in a qemu VM): >> >> >> NULL msg->security at that point is a bug in the ipc subsystem; SELinux is >> just the messenger. Normally msg->security is set for every allocated msg >> by load_msg() -> security_msg_msg_alloc() -> >> selinux_msg_msg_alloc_security(), and freed/cleared upon free_msg() -> >> security_msg_msg_free() -> selinux_msg_msg_free_security(). Looking around, >> I see copy_msg() introduced for checkpoint-restore initializes dst->security >> to NULL but never sets it properly? > > I am indeed building with CONFIG_CHECKPOINT_RESTORE=y, so your > analysis seems to be correct.
(cc originator of the bug)
If I am reading this correctly, then when the copy msg was created, a msg security struct was already allocated (prepare_copy->load_msg->security_msg_msg_alloc). So having copy_msg() clear dst->security is also a memory leak in addition to leading to this oops. Attached is a possible, un-tested fix.
> >>> >>> [12578.053111] BUG: unable to handle kernel NULL pointer dereference >>> at (null) >>> [12578.054025] IP: [<ffffffff8131e1da>] >>> selinux_msg_queue_msgrcv+0xda/0x1e0 >>> [12578.054025] PGD 29961067 PUD 34dc5067 PMD 0 >>> [12578.054025] Oops: 0000 [#2] SMP >>> [12578.054025] CPU 1 >>> [12578.054025] Pid: 23453, comm: trinity-child23 Tainted: G D W >>> 3.8.0-rc6+ #31 Bochs Bochs >>> [12578.054025] RIP: 0010:[<ffffffff8131e1da>] [<ffffffff8131e1da>] >>> selinux_msg_queue_msgrcv+0xda/0x1e0 >>> [12578.054025] RSP: 0018:ffff88002b6b5e18 EFLAGS: 00010246 >>> [12578.054025] RAX: 0000000000000000 RBX: ffff88003132d410 RCX: >>> 0000000000000001 >>> [12578.054025] RDX: ffff88000e8bc560 RSI: 0000000000000001 RDI: >>> 0000000000000246 >>> [12578.054025] RBP: ffff88002b6b5e68 R08: 0000000000000000 R09: >>> 0000000000000000 >>> [12578.054025] R10: ffff88000e8bc560 R11: 0000000000000000 R12: >>> 0000000000000001 >>> [12578.054025] R13: 0000000000000000 R14: ffff880006449500 R15: >>> ffff88003132d410 >>> [12578.054025] FS: 00007f7385059700(0000) GS:ffff88003e200000(0000) >>> knlGS:0000000000000000 >>> [12578.054025] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >>> [12578.054025] CR2: 0000000000000000 CR3: 00000000303a2000 CR4: >>> 00000000000006e0 >>> [12578.054025] DR0: 0000000000000000 DR1: 0000000000000000 DR2: >>> 0000000000000000 >>> [12578.054025] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: >>> 0000000000000400 >>> [12578.054025] Process trinity-child23 (pid: 23453, threadinfo >>> ffff88002b6b4000, task ffff88000e8bc560) >>> [12578.054025] Stack: >>> [12578.054025] ffffffff8131e105 ffffffff81313f69 ffff88002b6b5e04 >>> ffffffff00000000 >>> [12578.054025] ffffffff812fd6f5 ffff88003a89c1c0 0000000000000000 >>> 0000000000000001 >>> [12578.054025] 0000000000000000 ffff88003132d4c0 ffff88002b6b5e78 >>> ffffffff81314086 >>> [12578.054025] Call Trace: >>> [12578.054025] [<ffffffff8131e105>] ? selinux_msg_queue_msgrcv+0x5/0x1e0 >>> [12578.054025] [<ffffffff81313f69>] ? security_ipc_permission+0x19/0x20 >>> [12578.054025] [<ffffffff812fd6f5>] ? ipc_lock+0x5/0x1c0 >>> [12578.054025] [<ffffffff81314086>] security_msg_queue_msgrcv+0x16/0x20 >>> [12578.054025] [<ffffffff812ff93f>] do_msgrcv+0x1ef/0x6e0 >>> [12578.054025] [<ffffffff812fe340>] ? load_msg+0x180/0x180 >>> [12578.054025] [<ffffffff81373184>] ? lockdep_sys_exit_thunk+0x35/0x67 >>> [12578.054025] [<ffffffff810fb236>] ? trace_hardirqs_on_caller+0x16/0x1a0 >>> [12578.054025] [<ffffffff8137310e>] ? trace_hardirqs_on_thunk+0x3a/0x3f >>> [12578.054025] [<ffffffff812ffe45>] sys_msgrcv+0x15/0x20 >>> [12578.054025] [<ffffffff81cfe9d9>] system_call_fastpath+0x16/0x1b >>> [12578.054025] Code: 4c 8d 45 c0 45 31 c9 b9 10 00 00 00 44 89 e7 4d >>> 8b 6d 28 c6 45 c0 04 89 55 c8 8b 70 04 ba 1b 00 00 00 e8 fa 7a ff ff >>> 85 c0 75 1d <41> 8b 75 00 4c 8d 45 c0 45 31 c9 b9 02 00 00 00 ba 1a 00 >>> 00 00 >>> [12578.054025] RIP [<ffffffff8131e1da>] >>> selinux_msg_queue_msgrcv+0xda/0x1e0 >>> [12578.054025] RSP <ffff88002b6b5e18> >>> [12578.054025] CR2: 0000000000000000 >>> [12578.142292] ---[ end trace 36aee1c7bfea7f83 ]--- >>> >>> >>> After adding: >>> >>> diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c >>> index 54aaa72..20cec57 100644 >>> --- a/security/selinux/hooks.c >>> +++ b/security/selinux/hooks.c >>> @@ -4982,9 +4982,12 @@ static int selinux_msg_queue_msgrcv(struct >>> msg_queue *msq, struct msg_msg *msg, >>> >>> rc = avc_has_perm(sid, isec->sid, >>> SECCLASS_MSGQ, MSGQ__READ, &ad); >>> - if (!rc) >>> + if (!rc) { >>> + WARN(msec == NULL, "msec is NULL!"); >>> + >>> rc = avc_has_perm(sid, msec->sid, >>> SECCLASS_MSG, MSG__RECEIVE, &ad); >>> + } >>> return rc; >>> } >>> >>> >>> I see: >>> >>> [ 43.103283] ------------[ cut here ]------------ >>> [ 43.104236] WARNING: at >>> /home/ttrantal/git/linux-2.6/security/selinux/hooks.c:4986 >>> selinux_msg_queue_msgrcv+0x1ff/0x210() >>> [ 43.106088] Hardware name: Bochs >>> [ 43.106640] msec is NULL!Pid: 2387, comm: trinity-child9 Not >>> tainted 3.8.0-rc6+ #37 >>> [ 43.107950] Call Trace: >>> [ 43.108393] [<ffffffff8131e12f>] ? >>> selinux_msg_queue_msgrcv+0x1ff/0x210 >>> [ 43.109534] [<ffffffff8109ac1a>] warn_slowpath_common+0x7a/0xb0 >>> [ 43.110565] [<ffffffff8109acc6>] warn_slowpath_fmt+0x46/0x50 >>> [ 43.111561] [<ffffffff8131e12f>] selinux_msg_queue_msgrcv+0x1ff/0x210 >>> [ 43.112677] [<ffffffff8131df35>] ? selinux_msg_queue_msgrcv+0x5/0x210 >>> [ 43.113808] [<ffffffff81313f99>] ? security_ipc_permission+0x19/0x20 >>> [ 43.114919] [<ffffffff812fd725>] ? ipc_lock+0x5/0x1c0 >>> [ 43.115817] [<ffffffff813140b6>] security_msg_queue_msgrcv+0x16/0x20 >>> [ 43.116929] [<ffffffff812ff96f>] do_msgrcv+0x1ef/0x6e0 >>> [ 43.117909] [<ffffffff812fe370>] ? load_msg+0x180/0x180 >>> [ 43.118850] [<ffffffff810fb35d>] ? >>> trace_hardirqs_on_caller+0x10d/0x1a0 >>> [ 43.120019] [<ffffffff8137315e>] ? trace_hardirqs_on_thunk+0x3a/0x3f >>> [ 43.121126] [<ffffffff812ffe75>] sys_msgrcv+0x15/0x20 >>> [ 43.122001] [<ffffffff81cfea19>] system_call_fastpath+0x16/0x1b >>> [ 43.123044] ---[ end trace db5952f0fa3bedc7 ]--- >>> [ 43.123815] >>> [ 43.124096] =============================== >>> [ 43.124804] [ INFO: suspicious RCU usage. ] >>> [ 43.125531] 3.8.0-rc6+ #37 Tainted: G W >>> [ 43.126344] ------------------------------- >>> [ 43.127083] /home/ttrantal/git/linux-2.6/include/linux/rcupdate.h:468 >>> Illegal context switch in RCU read-side critical section! >>> [ 43.129015] >>> [ 43.129015] other info that might help us debug this: >>> [ 43.129015] >>> [ 43.130367] >>> [ 43.130367] rcu_scheduler_active = 1, debug_locks = 0 >>> [ 43.131481] 3 locks held by trinity-child9/2387: >>> [ 43.132266] #0: (rcu_read_lock){.+.+..}, at: [<ffffffff812fd725>] >>> ipc_lock+0x5/0x1c0 >>> [ 43.133709] #1: (&(&new->lock)->rlock){+.+...}, at: >>> [<ffffffff812fd7a1>] ipc_lock+0x81/0x1c0 >>> [ 43.135294] #2: (&mm->mmap_sem){++++++}, at: [<ffffffff8108e1d4>] >>> __do_page_fault+0x114/0x4e0 >>> [ 43.136864] >>> [ 43.136864] stack backtrace: >>> [ 43.137619] Pid: 2387, comm: trinity-child9 Tainted: G W >>> 3.8.0-rc6+ #37 >>> [ 43.138897] Call Trace: >>> [ 43.139338] [<ffffffff810fdd1d>] lockdep_rcu_suspicious+0xfd/0x130 >>> [ 43.140417] [<ffffffff81cfb783>] __schedule+0x543/0x900 >>> [ 43.141342] [<ffffffff810d38ba>] __cond_resched+0x2a/0x40 >>> [ 43.142291] [<ffffffff8108e1d4>] ? __do_page_fault+0x114/0x4e0 >>> [ 43.143440] [<ffffffff81cfbc6f>] _cond_resched+0x2f/0x40 >>> [ 43.144362] [<ffffffff8108e1e1>] __do_page_fault+0x121/0x4e0 >>> [ 43.145362] [<ffffffff810fb3fd>] ? trace_hardirqs_on+0xd/0x10 >>> [ 43.146316] [<ffffffff8137319d>] ? trace_hardirqs_off_thunk+0x3a/0x3c >>> [ 43.147386] [<ffffffff8108e5de>] do_page_fault+0xe/0x10 >>> [ 43.148254] [<ffffffff810889fa>] do_async_page_fault+0x2a/0xa0 >>> [ 43.149239] [<ffffffff81cfe138>] async_page_fault+0x28/0x30 >>> [ 43.150167] [<ffffffff8131e017>] ? selinux_msg_queue_msgrcv+0xe7/0x210 >>> [ 43.151263] [<ffffffff8131e12f>] ? >>> selinux_msg_queue_msgrcv+0x1ff/0x210 >>> [ 43.152357] [<ffffffff8131df35>] ? selinux_msg_queue_msgrcv+0x5/0x210 >>> [ 43.153475] [<ffffffff81313f99>] ? security_ipc_permission+0x19/0x20 >>> [ 43.154828] [<ffffffff812fd725>] ? ipc_lock+0x5/0x1c0 >>> [ 43.156052] [<ffffffff813140b6>] security_msg_queue_msgrcv+0x16/0x20 >>> [ 43.157586] [<ffffffff812ff96f>] do_msgrcv+0x1ef/0x6e0 >>> [ 43.158830] [<ffffffff812fe370>] ? load_msg+0x180/0x180 >>> [ 43.160131] [<ffffffff810fb35d>] ? >>> trace_hardirqs_on_caller+0x10d/0x1a0 >>> [ 43.161736] [<ffffffff8137315e>] ? trace_hardirqs_on_thunk+0x3a/0x3f >>> [ 43.163238] [<ffffffff812ffe75>] sys_msgrcv+0x15/0x20 >>> [ 43.164453] [<ffffffff81cfea19>] system_call_fastpath+0x16/0x1b >>> [ 43.176035] BUG: unable to handle kernel NULL pointer dereference >>> at (null) >>> [ 43.177016] IP: [<ffffffff8131e017>] >>> selinux_msg_queue_msgrcv+0xe7/0x210 >>> [ 43.177016] PGD 3189b067 PUD 3189c067 PMD 0 >>> [ 43.177016] Oops: 0000 [#1] SMP >>> [ 43.177016] CPU 0 >>> [ 43.177016] Pid: 2387, comm: trinity-child9 Tainted: G W >>> 3.8.0-rc6+ #37 Bochs Bochs >>> [ 43.177016] RIP: 0010:[<ffffffff8131e017>] [<ffffffff8131e017>] >>> selinux_msg_queue_msgrcv+0xe7/0x210 >>> [ 43.177016] RSP: 0018:ffff8800318a7e18 EFLAGS: 00010296 >>> [ 43.177016] RAX: 0000000000000000 RBX: ffff880032e0e810 RCX: >>> 0000000000000006 >>> [ 43.177016] RDX: 0000000000003e50 RSI: ffff88003b7c4c68 RDI: >>> 0000000000000009 >>> [ 43.177016] RBP: ffff8800318a7e68 R08: 0000000000000001 R09: >>> 0000000000000000 >>> [ 43.177016] R10: 0000000000000000 R11: 0000000000000288 R12: >>> 0000000000000001 >>> [ 43.177016] R13: 0000000000000000 R14: ffff88003b22ae80 R15: >>> ffff880032e0e810 >>> [ 43.177016] FS: 00007fc6ba864700(0000) GS:ffff88003fc00000(0000) >>> knlGS:0000000000000000 >>> [ 43.177016] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >>> [ 43.177016] CR2: 00007fc6ba6471f0 CR3: 0000000031898000 CR4: >>> 00000000000006f0 >>> [ 43.177016] DR0: 0000000000000000 DR1: 0000000000000000 DR2: >>> 0000000000000000 >>> [ 43.177016] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: >>> 0000000000000400 >>> [ 43.177016] Process trinity-child9 (pid: 2387, threadinfo >>> ffff8800318a6000, task ffff88003b7c4560) >>> [ 43.177016] Stack: >>> [ 43.177016] ffffffff8131df35 ffffffff81313f99 ffff8800318a7e04 >>> ffffffff5d6d982a >>> [ 43.177016] ffffffff812fd725 ffff880039c675c0 0000000000000000 >>> 0000000000000001 >>> [ 43.177016] 0000000000000000 ffff880032e0e8c0 ffff8800318a7e78 >>> ffffffff813140b6 >>> [ 43.177016] Call Trace: >>> [ 43.177016] [<ffffffff8131df35>] ? selinux_msg_queue_msgrcv+0x5/0x210 >>> [ 43.177016] [<ffffffff81313f99>] ? security_ipc_permission+0x19/0x20 >>> [ 43.177016] [<ffffffff812fd725>] ? ipc_lock+0x5/0x1c0 >>> [ 43.177016] [<ffffffff813140b6>] security_msg_queue_msgrcv+0x16/0x20 >>> [ 43.177016] [<ffffffff812ff96f>] do_msgrcv+0x1ef/0x6e0 >>> [ 43.177016] [<ffffffff812fe370>] ? load_msg+0x180/0x180 >>> [ 43.177016] [<ffffffff810fb35d>] ? >>> trace_hardirqs_on_caller+0x10d/0x1a0 >>> [ 43.177016] [<ffffffff8137315e>] ? trace_hardirqs_on_thunk+0x3a/0x3f >>> [ 43.177016] [<ffffffff812ffe75>] sys_msgrcv+0x15/0x20 >>> [ 43.177016] [<ffffffff81cfea19>] system_call_fastpath+0x16/0x1b >>> [ 43.177016] Code: 00 00 00 44 89 e7 4d 8b 6d 28 c6 45 c0 04 89 55 >>> c8 8b 70 04 ba 1b 00 00 00 e8 f6 7c ff ff 85 c0 75 26 4d 85 ed 0f 84 >>> 00 01 00 00 <41> 8b 75 00 4c 8d 45 c0 45 31 c9 b9 02 00 00 00 ba 1a 00 >>> 00 00 >>> [ 43.177016] RIP [<ffffffff8131e017>] >>> selinux_msg_queue_msgrcv+0xe7/0x210 >>> [ 43.177016] RSP <ffff8800318a7e18> >>> [ 43.177016] CR2: 0000000000000000 >>> [ 43.228535] ---[ end trace db5952f0fa3bedc8 ]--- >>> [ 68.106008] BUG: soft lockup - CPU#0 stuck for 22s! >>> [trinity-child8:2382] >>> >>> Tommi >>> >>
From 694502e960af954c4203d1b76837e51ce6720576 Mon Sep 17 00:00:00 2001 From: Stephen Smalley <sds@tycho.nsa.gov> Date: Wed, 6 Feb 2013 11:15:08 -0500 Subject: [PATCH] Fix selinux_msg_queue_msgrcv() oops.
Fix an oops in selinux_msg_queue_msgrcv() by ensuring that copied messages preserve security information.
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov> Reported-by: Tommi Rantala <tt.rantala@gmail.com> --- include/linux/security.h | 12 ++++++++++++ ipc/msgutil.c | 6 +++++- security/security.c | 5 +++++ security/selinux/hooks.c | 10 ++++++++++ 4 files changed, 32 insertions(+), 1 deletion(-)
diff --git a/include/linux/security.h b/include/linux/security.h index eee7478..4737635 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -1126,6 +1126,11 @@ static inline void security_free_mnt_opts(struct security_mnt_opts *opts) * created. * @msg contains the message structure to be modified. * Return 0 if operation was successful and permission is granted. + * @msg_msg_copy_security: + * Propagate security information on a msg copy operation. + * @src contains the source message structure. + * @dst contains the destination message structure. + * Return 0 if operation was successful. * @msg_msg_free_security: * Deallocate the security structure for this message. * @msg contains the message structure to be modified. @@ -1553,6 +1558,7 @@ struct security_operations { void (*ipc_getsecid) (struct kern_ipc_perm *ipcp, u32 *secid); int (*msg_msg_alloc_security) (struct msg_msg *msg); + int (*msg_msg_copy_security) (struct msg_msg *src, struct msg_msg *dst); void (*msg_msg_free_security) (struct msg_msg *msg); int (*msg_queue_alloc_security) (struct msg_queue *msq); @@ -1811,6 +1817,7 @@ void security_task_to_inode(struct task_struct *p, struct inode *inode); int security_ipc_permission(struct kern_ipc_perm *ipcp, short flag); void security_ipc_getsecid(struct kern_ipc_perm *ipcp, u32 *secid); int security_msg_msg_alloc(struct msg_msg *msg); +int security_msg_msg_copy(struct msg_msg *src, struct msg_msg *dst); void security_msg_msg_free(struct msg_msg *msg); int security_msg_queue_alloc(struct msg_queue *msq); void security_msg_queue_free(struct msg_queue *msq); @@ -2409,6 +2416,11 @@ static inline int security_msg_msg_alloc(struct msg_msg *msg) return 0; } +static inline int security_msg_msg_copy(struct msg_msg *src, struct msg_msg *dst) +{ + return 0; +} + static inline void security_msg_msg_free(struct msg_msg *msg) { } diff --git a/ipc/msgutil.c b/ipc/msgutil.c index ebfcbfa..7837257 100644 --- a/ipc/msgutil.c +++ b/ipc/msgutil.c @@ -108,6 +108,7 @@ struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst) struct msg_msgseg *dst_pseg, *src_pseg; int len = src->m_ts; int alen; + int err; BUG_ON(dst == NULL); if (src->m_ts > dst->m_ts) @@ -118,7 +119,10 @@ struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst) alen = DATALEN_MSG; dst->next = NULL; - dst->security = NULL; + + err = security_msg_msg_copy(src, dst); + if (err < 0) + return ERR_PTR(err); memcpy(dst + 1, src + 1, alen); diff --git a/security/security.c b/security/security.c index 7b88c6a..85cd39d 100644 --- a/security/security.c +++ b/security/security.c @@ -936,6 +936,11 @@ int security_msg_msg_alloc(struct msg_msg *msg) return security_ops->msg_msg_alloc_security(msg); } +int security_msg_msg_copy(struct msg_msg *src, struct msg_msg *dst) +{ + return security_ops->msg_msg_copy_security(src, dst); +} + void security_msg_msg_free(struct msg_msg *msg) { security_ops->msg_msg_free_security(msg); diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index ef26e96..79f93ad 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -4840,6 +4840,15 @@ static int selinux_msg_msg_alloc_security(struct msg_msg *msg) return msg_msg_alloc_security(msg); } +static int selinux_msg_msg_copy_security(struct msg_msg *src, struct msg_msg *dst) +{ + struct msg_security_struct *smsec, *dmsec; + smsec = src->security; + dmsec = dst->security; + dmsec->sid = smsec->sid; + return 0; +} + static void selinux_msg_msg_free_security(struct msg_msg *msg) { msg_msg_free_security(msg); @@ -5603,6 +5612,7 @@ static struct security_operations selinux_ops = { .ipc_getsecid = selinux_ipc_getsecid, .msg_msg_alloc_security = selinux_msg_msg_alloc_security, + .msg_msg_copy_security = selinux_msg_msg_copy_security, .msg_msg_free_security = selinux_msg_msg_free_security, .msg_queue_alloc_security = selinux_msg_queue_alloc_security, -- 1.7.11.7
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