linux/security/integrity/ima, branch v3.15.8

ima: introduce ima_kernel_read()

2014-06-26T19:17:33Z

commit 0430e49b6e7c6b5e076be8fefdee089958c9adad upstream. 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: [] 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:[] [] 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] [] ? aa_path_name+0x2ab/0x430 [ 106.751199] [] ? sched_clock+0x9/0x10 [ 106.751225] [] aa_path_perm+0x7d/0x170 [ 106.751250] [] ? native_sched_clock+0x15/0x80 [ 106.751276] [] aa_file_perm+0x33/0x40 [ 106.751301] [] common_file_perm+0x8e/0xb0 [ 106.751327] [] apparmor_file_permission+0x18/0x20 [ 106.751355] [] security_file_permission+0x23/0xa0 [ 106.751382] [] rw_verify_area+0x52/0xe0 [ 106.751407] [] vfs_read+0x6d/0x170 [ 106.751432] [] kernel_read+0x41/0x60 [ 106.751457] [] ima_calc_file_hash+0x225/0x280 [ 106.751483] [] ? ima_calc_file_hash+0x32/0x280 [ 106.751509] [] ima_collect_measurement+0x9d/0x160 [ 106.751536] [] ? trace_hardirqs_on+0xd/0x10 [ 106.751562] [] ? ima_file_free+0x6c/0xd0 [ 106.751587] [] ima_update_xattr+0x34/0x60 [ 106.751612] [] ima_file_free+0xc0/0xd0 [ 106.751637] [] __fput+0xd5/0x300 [ 106.751662] [] ____fput+0xe/0x10 [ 106.751687] [] task_work_run+0xc4/0xe0 [ 106.751712] [] do_exit+0x2bd/0xa90 [ 106.751738] [] ? retint_swapgs+0x13/0x1b [ 106.751763] [] do_group_exit+0x4c/0xc0 [ 106.751788] [] SyS_exit_group+0x14/0x20 [ 106.751814] [] 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 [] our_mnt+0x1a/0x30 [ 106.752214] RSP [ 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 Suggested-by: Eric W. Biederman Signed-off-by: Mimi Zohar Signed-off-by: Greg Kroah-Hartman

ima: audit log files opened with O_DIRECT flag

2014-06-26T19:17:33Z

commit f9b2a735bdddf836214b5dca74f6ca7712e5a08c upstream. Files are measured or appraised based on the IMA policy. When a file, in policy, is opened with the O_DIRECT flag, a deadlock occurs. The first attempt at resolving this lockdep temporarily removed the O_DIRECT flag and restored it, after calculating the hash. The second attempt introduced the O_DIRECT_HAVELOCK flag. Based on this flag, do_blockdev_direct_IO() would skip taking the i_mutex a second time. The third attempt, by Dmitry Kasatkin, resolves the i_mutex locking issue, by re-introducing the IMA mutex, but uncovered another problem. Reading a file with O_DIRECT flag set, writes directly to userspace pages. A second patch allocates a user-space like memory. This works for all IMA hooks, except ima_file_free(), which is called on __fput() to recalculate the file hash. Until this last issue is addressed, do not 'collect' the measurement for measuring, appraising, or auditing files opened with the O_DIRECT flag set. Based on policy, permit or deny file access. This patch defines a new IMA policy rule option named 'permit_directio'. Policy rules could be defined, based on LSM or other criteria, to permit specific applications to open files with the O_DIRECT flag set. Changelog v1: - permit or deny file access based IMA policy rules Signed-off-by: Mimi Zohar Acked-by: Dmitry Kasatkin Signed-off-by: Greg Kroah-Hartman

ima: skip memory allocation for empty files

2014-03-07T17:15:48Z

Memory allocation is unnecessary for empty files. This patch calculates the hash without memory allocation. Signed-off-by: Dmitry Kasatkin Signed-off-by: Mimi Zohar

ima: return d_name.name if d_path fails

2014-03-07T17:15:46Z

This is a small refactoring so ima_d_path() returns dentry name if path reconstruction fails. It simplifies callers actions and removes code duplication. Signed-off-by: Dmitry Kasatkin Signed-off-by: Mimi Zohar

integrity: fix checkpatch errors

2014-03-07T17:15:45Z

Between checkpatch changes (eg. sizeof) and inconsistencies between Lindent and checkpatch, unfixed checkpatch errors make it difficult to see new errors. This patch fixes them. Some lines with over 80 chars remained unchanged to improve code readability. The "extern" keyword is removed from internal evm.h to make it consistent with internal ima.h. Signed-off-by: Dmitry Kasatkin Signed-off-by: Mimi Zohar

ima: fix erroneous removal of security.ima xattr

2014-03-07T17:15:44Z

ima_inode_post_setattr() calls ima_must_appraise() to check if the file needs to be appraised. If it does not then it removes security.ima xattr. With original policy matching code it might happen that even file needs to be appraised with FILE_CHECK hook, it might not be for POST_SETATTR hook. 'security.ima' might be erronously removed. This patch treats POST_SETATTR as special wildcard function and will cause ima_must_appraise() to be true if any of the hooks rules matches. security.ima will not be removed if any of the hooks would require appraisal. Signed-off-by: Dmitry Kasatkin Signed-off-by: Mimi Zohar

security: integrity: Use a more current logging style

2014-03-07T17:15:21Z

Convert printks to pr_. Add pr_fmt. Remove embedded prefixes. Signed-off-by: Joe Perches Signed-off-by: Mimi Zohar

ima: reduce memory usage when a template containing the n field is used

2014-03-07T16:32:30Z

Before this change, to correctly calculate the template digest for the 'ima' template, the event name field (id: 'n') length was set to the fixed size of 256 bytes. This patch reduces the length of the event name field to the string length incremented of one (to make room for the termination character '\0') and handles the specific case of the digest calculation for the 'ima' template directly in ima_calc_field_array_hash_tfm(). Signed-off-by: Roberto Sassu Signed-off-by: Mimi Zohar

ima: restore the original behavior for sending data with ima template

2014-03-07T16:32:29Z

With the new template mechanism introduced in IMA since kernel 3.13, the format of data sent through the binary_runtime_measurements interface is slightly changed. Now, for a generic measurement, the format of template data (after the template name) is: template_len | field1_len | field1 | ... | fieldN_len | fieldN In addition, fields containing a string now include the '\0' termination character. Instead, the format for the 'ima' template should be: SHA1 digest | event name length | event name It must be noted that while in the IMA 3.13 code 'event name length' is 'IMA_EVENT_NAME_LEN_MAX + 1' (256 bytes), so that the template digest is calculated correctly, and 'event name' contains '\0', in the pre 3.13 code 'event name length' is exactly the string length and 'event name' does not contain the termination character. The patch restores the behavior of the IMA code pre 3.13 for the 'ima' template so that legacy userspace tools obtain a consistent behavior when receiving data from the binary_runtime_measurements interface regardless of which kernel version is used. Signed-off-by: Roberto Sassu Cc: # 3.3.13: 3ce1217 ima: define template fields library Signed-off-by: Mimi Zohar

ima: use static const char array definitions

2014-03-07T16:30:36Z

A const char pointer allocates memory for a pointer as well as for a string, This patch replaces a number of the const char pointers throughout IMA, with a static const char array. Suggested-by: David Howells Signed-off-by: Mimi Zohar Acked-by: David Howells