Dmitry Kasatkin 0430e49b6e ima: introduce ima_kernel_read() ... Commit 8aac62706 "move exit_task_namespaces() outside of exit_notify" introduced the kernel opps since the kernel v3.10, which happens when Apparmor and IMA-appraisal are enabled at the same time. ---------------------------------------------------------------------- [ 106.750167] BUG: unable to handle kernel NULL pointer dereference at 0000000000000018 [ 106.750221] IP: [<ffffffff811ec7da>] our_mnt+0x1a/0x30 [ 106.750241] PGD 0 [ 106.750254] Oops: 0000 [#1] SMP [ 106.750272] Modules linked in: cuse parport_pc ppdev bnep rfcomm bluetooth rpcsec_gss_krb5 nfsd auth_rpcgss nfs_acl nfs lockd sunrpc fscache dm_crypt intel_rapl x86_pkg_temp_thermal intel_powerclamp kvm_intel snd_hda_codec_hdmi kvm crct10dif_pclmul crc32_pclmul ghash_clmulni_intel aesni_intel aes_x86_64 glue_helper lrw gf128mul ablk_helper cryptd snd_hda_codec_realtek dcdbas snd_hda_intel snd_hda_codec snd_hwdep snd_pcm snd_page_alloc snd_seq_midi snd_seq_midi_event snd_rawmidi psmouse snd_seq microcode serio_raw snd_timer snd_seq_device snd soundcore video lpc_ich coretemp mac_hid lp parport mei_me mei nbd hid_generic e1000e usbhid ahci ptp hid libahci pps_core [ 106.750658] CPU: 6 PID: 1394 Comm: mysqld Not tainted 3.13.0-rc7-kds+ #15 [ 106.750673] Hardware name: Dell Inc. OptiPlex 9010/0M9KCM, BIOS A08 09/19/2012 [ 106.750689] task: ffff8800de804920 ti: ffff880400fca000 task.ti: ffff880400fca000 [ 106.750704] RIP: 0010:[<ffffffff811ec7da>] [<ffffffff811ec7da>] our_mnt+0x1a/0x30 [ 106.750725] RSP: 0018:ffff880400fcba60 EFLAGS: 00010286 [ 106.750738] RAX: 0000000000000000 RBX: 0000000000000100 RCX: ffff8800d51523e7 [ 106.750764] RDX: ffffffffffffffea RSI: ffff880400fcba34 RDI: ffff880402d20020 [ 106.750791] RBP: ffff880400fcbae0 R08: 0000000000000000 R09: 0000000000000001 [ 106.750817] R10: 0000000000000000 R11: 0000000000000001 R12: ffff8800d5152300 [ 106.750844] R13: ffff8803eb8df510 R14: ffff880400fcbb28 R15: ffff8800d51523e7 [ 106.750871] FS: 0000000000000000(0000) GS:ffff88040d200000(0000) knlGS:0000000000000000 [ 106.750910] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 106.750935] CR2: 0000000000000018 CR3: 0000000001c0e000 CR4: 00000000001407e0 [ 106.750962] Stack: [ 106.750981] ffffffff813434eb ffff880400fcbb20 ffff880400fcbb18 0000000000000000 [ 106.751037] ffff8800de804920 ffffffff8101b9b9 0001800000000000 0000000000000100 [ 106.751093] 0000010000000000 0000000000000002 000000000000000e ffff8803eb8df500 [ 106.751149] Call Trace: [ 106.751172] [<ffffffff813434eb>] ? aa_path_name+0x2ab/0x430 [ 106.751199] [<ffffffff8101b9b9>] ? sched_clock+0x9/0x10 [ 106.751225] [<ffffffff8134a68d>] aa_path_perm+0x7d/0x170 [ 106.751250] [<ffffffff8101b945>] ? native_sched_clock+0x15/0x80 [ 106.751276] [<ffffffff8134aa73>] aa_file_perm+0x33/0x40 [ 106.751301] [<ffffffff81348c5e>] common_file_perm+0x8e/0xb0 [ 106.751327] [<ffffffff81348d78>] apparmor_file_permission+0x18/0x20 [ 106.751355] [<ffffffff8130c853>] security_file_permission+0x23/0xa0 [ 106.751382] [<ffffffff811c77a2>] rw_verify_area+0x52/0xe0 [ 106.751407] [<ffffffff811c789d>] vfs_read+0x6d/0x170 [ 106.751432] [<ffffffff811cda31>] kernel_read+0x41/0x60 [ 106.751457] [<ffffffff8134fd45>] ima_calc_file_hash+0x225/0x280 [ 106.751483] [<ffffffff8134fb52>] ? ima_calc_file_hash+0x32/0x280 [ 106.751509] [<ffffffff8135022d>] ima_collect_measurement+0x9d/0x160 [ 106.751536] [<ffffffff810b552d>] ? trace_hardirqs_on+0xd/0x10 [ 106.751562] [<ffffffff8134f07c>] ? ima_file_free+0x6c/0xd0 [ 106.751587] [<ffffffff81352824>] ima_update_xattr+0x34/0x60 [ 106.751612] [<ffffffff8134f0d0>] ima_file_free+0xc0/0xd0 [ 106.751637] [<ffffffff811c9635>] __fput+0xd5/0x300 [ 106.751662] [<ffffffff811c98ae>] ____fput+0xe/0x10 [ 106.751687] [<ffffffff81086774>] task_work_run+0xc4/0xe0 [ 106.751712] [<ffffffff81066fad>] do_exit+0x2bd/0xa90 [ 106.751738] [<ffffffff8173c958>] ? retint_swapgs+0x13/0x1b [ 106.751763] [<ffffffff8106780c>] do_group_exit+0x4c/0xc0 [ 106.751788] [<ffffffff81067894>] SyS_exit_group+0x14/0x20 [ 106.751814] [<ffffffff8174522d>] system_call_fastpath+0x1a/0x1f [ 106.751839] Code: c3 0f 1f 44 00 00 55 48 89 e5 e8 22 fe ff ff 5d c3 0f 1f 44 00 00 55 65 48 8b 04 25 c0 c9 00 00 48 8b 80 28 06 00 00 48 89 e5 5d <48> 8b 40 18 48 39 87 c0 00 00 00 0f 94 c0 c3 0f 1f 80 00 00 00 [ 106.752185] RIP [<ffffffff811ec7da>] our_mnt+0x1a/0x30 [ 106.752214] RSP <ffff880400fcba60> [ 106.752236] CR2: 0000000000000018 [ 106.752258] ---[ end trace 3c520748b4732721 ]--- ---------------------------------------------------------------------- The reason for the oops is that IMA-appraisal uses "kernel_read()" when file is closed. kernel_read() honors LSM security hook which calls Apparmor handler, which uses current->nsproxy->mnt_ns. The 'guilty' commit changed the order of cleanup code so that nsproxy->mnt_ns was not already available for Apparmor. Discussion about the issue with Al Viro and Eric W. Biederman suggested that kernel_read() is too high-level for IMA. Another issue, except security checking, that was identified is mandatory locking. kernel_read honors it as well and it might prevent IMA from calculating necessary hash. It was suggested to use simplified version of the function without security and locking checks. This patch introduces special version ima_kernel_read(), which skips security and mandatory locking checking. It prevents the kernel oops to happen. Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com> Suggested-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com> Cc: <stable@vger.kernel.org>		2014-06-12 17:58:08 -04:00
..
evm	evm: prohibit userspace writing 'security.evm' HMAC value	2014-06-12 17:58:07 -04:00
ima	ima: introduce ima_kernel_read()	2014-06-12 17:58:08 -04:00
digsig_asymmetric.c	ima: read and use signature hash algorithm	2013-10-25 17:16:59 -04:00
digsig.c	Revert "ima: define '_ima' as a builtin 'trusted' keyring"	2013-11-23 16:36:35 -08:00
iint.c	integrity: fix checkpatch errors	2014-03-07 12:15:45 -05:00
integrity_audit.c	Merge git://git.infradead.org/users/eparis/audit	2014-04-12 12:38:53 -07:00
integrity.h	ima: audit log files opened with O_DIRECT flag	2014-06-03 14:21:50 -05:00
Kconfig	integrity: move integrity_audit_msg()	2013-06-20 07:47:49 -04:00
Makefile	security: cleanup Makefiles to use standard syntax for specifying sub-directories	2014-02-17 11:08:04 +11:00