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  1. 12 Sep, 2012 2 commits
  3. 07 Sep, 2012 11 commits
    • Dmitry Kasatkin's avatar
      ima: digital signature verification support · 8606404f
      Dmitry Kasatkin authored 
      This patch adds support for digital signature based integrity appraisal.
With this patch, 'security.ima' contains either the file data hash or
a digital signature of the file data hash. The file data hash provides
the security attribute of file integrity. In addition to file integrity,
a digital signature provides the security attribute of authenticity.

Unlike EVM, when the file metadata changes, the digital signature is
replaced with an HMAC, modification of the file data does not cause the
'security.ima' digital signature to be replaced with a hash. As a
result, after any modification, subsequent file integrity appraisals
would fail.

Although digitally signed files can be modified, but by not updating
'security.ima' to reflect these modifications, in essence digitally
signed files could be considered 'immutable'.

IMA uses a different keyring than EVM. While the EVM keyring should not
be updated after initialization and locked, the IMA keyring should allow
updating or adding new keys when upgrading or installing packages.

Changelog v4:
- Change IMA_DIGSIG to hex equivalent
Changelog v3:
- Permit files without any 'security.ima' xattr to be labeled properly.
Signed-off-by: default avatarDmitry Kasatkin <dmitry.kasatkin@intel.com>
Signed-off-by: default avatarMimi Zohar <zohar@linux.vnet.ibm.com>
      8606404f
    • Mimi Zohar's avatar
      ima: add support for different security.ima data types · 5a44b412
      Mimi Zohar authored 
      IMA-appraisal currently verifies the integrity of a file based on a
known 'good' measurement value.  This patch reserves the first byte
of 'security.ima' as a place holder for the type of method used for
verifying file data integrity.

Changelog v1:
- Use the newly defined 'struct evm_ima_xattr_data'
Signed-off-by: default avatarDmitry Kasatkin <dmitry.kasatkin@nokia.com>
Signed-off-by: default avatarMimi Zohar <zohar@linux.vnet.ibm.com>
      5a44b412
    • Mimi Zohar's avatar
      ima: add ima_inode_setxattr/removexattr function and calls · 42c63330
      Mimi Zohar authored 
      Based on xattr_permission comments, the restriction to modify 'security'
xattr is left up to the underlying fs or lsm. Ensure that not just anyone
can modify or remove 'security.ima'.

Changelog v1:
- Unless IMA-APPRAISE is configured, use stub ima_inode_removexattr()/setxattr()
  functions.  (Moved ima_inode_removexattr()/setxattr() to ima_appraise.c)

Changelog:
  - take i_mutex to fix locking (Dmitry Kasatkin)
  - ima_reset_appraise_flags should only be called when modifying or
    removing the 'security.ima' xattr. Requires CAP_SYS_ADMIN privilege.
    (Incorporated fix from Roberto Sassu)
  - Even if allowed to update security.ima, reset the appraisal flags,
    forcing re-appraisal.
  - Replace CAP_MAC_ADMIN with CAP_SYS_ADMIN
  - static inline ima_inode_setxattr()/ima_inode_removexattr() stubs
  - ima_protect_xattr should be static
Signed-off-by: default avatarMimi Zohar <zohar@us.ibm.com>
Signed-off-by: default avatarDmitry Kasatkin <dmitry.kasatkin@intel.com>
      42c63330
    • Mimi Zohar's avatar
      ima: add inode_post_setattr call · 9957a504
      Mimi Zohar authored 
      Changing an inode's metadata may result in our not needing to appraise
the file.  In such cases, we must remove 'security.ima'.

Changelog v1:
- use ima_inode_post_setattr() stub function, if IMA_APPRAISE not configured
Signed-off-by: default avatarMimi Zohar <zohar@us.ibm.com>
Acked-by: default avatarSerge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: default avatarDmitry Kasatkin <dmitry.kasatkin@intel.com>
      9957a504
    • Dmitry Kasatkin's avatar
      ima: replace iint spinblock with rwlock/read_lock · a10bf26b
      Dmitry Kasatkin authored 
      For performance, replace the iint spinlock with rwlock/read_lock.

Eric Paris questioned this change, from spinlocks to rwlocks, saying
"rwlocks have been shown to actually be slower on multi processor
systems in a number of cases due to the cache line bouncing required."

Based on performance measurements compiling the kernel on a cold
boot with multiple jobs with/without this patch, Dmitry Kasatkin
and I found that rwlocks performed better than spinlocks, but very
insignificantly.  For example with total compilation time around 6
minutes, with rwlocks time was 1 - 3 seconds shorter... but always
like that.

Changelog v2:
- new patch taken from the 'allocating iint improvements' patch
Signed-off-by: default avatarDmitry Kasatkin <dmitry.kasatkin@intel.com>
Signed-off-by: default avatarMimi Zohar <zohar@us.ibm.com>
      a10bf26b
    • Dmitry Kasatkin's avatar
      ima: allocating iint improvements · bf2276d1
      Dmitry Kasatkin authored 
      With IMA-appraisal's removal of the iint mutex and taking the i_mutex
instead, allocating the iint becomes a lot simplier, as we don't need
to be concerned with two processes racing to allocate the iint. This
patch cleans up and improves performance for allocating the iint.

- removed redundant double i_mutex locking
- combined iint allocation with tree search

Changelog v2:
- removed the rwlock/read_lock changes from this patch
Signed-off-by: default avatarDmitry Kasatkin <dmitry.kasatkin@intel.com>
Signed-off-by: default avatarMimi Zohar <zohar@us.ibm.com>
      bf2276d1
    • Mimi Zohar's avatar
      ima: add appraise action keywords and default rules · 07f6a794
      Mimi Zohar authored 
      Unlike the IMA measurement policy, the appraise policy can not be dependent
on runtime process information, such as the task uid, as the 'security.ima'
xattr is written on file close and must be updated each time the file changes,
regardless of the current task uid.

This patch extends the policy language with 'fowner', defines an appraise
policy, which appraises all files owned by root, and defines 'ima_appraise_tcb',
a new boot command line option, to enable the appraise policy.

Changelog v3:
- separate the measure from the appraise rules in order to support measuring
  without appraising and appraising without measuring.
- change appraisal default for filesystems without xattr support to fail
- update default appraise policy for cgroups

Changelog v1:
- don't appraise RAMFS (Dmitry Kasatkin)
- merged rest of "ima: ima_must_appraise_or_measure API change" commit
  (Dmtiry Kasatkin)

  ima_must_appraise_or_measure() called ima_match_policy twice, which
  searched the policy for a matching rule.  Once for a matching measurement
  rule and subsequently for an appraisal rule. Searching the policy twice
  is unnecessary overhead, which could be noticeable with a large policy.

  The new version of ima_must_appraise_or_measure() does everything in a
  single iteration using a new version of ima_match_policy().  It returns
  IMA_MEASURE, IMA_APPRAISE mask.

  With the use of action mask only one efficient matching function
  is enough.  Removed other specific versions of matching functions.

Changelog:
- change 'owner' to 'fowner' to conform to the new LSM conditions posted by
  Roberto Sassu.
- fix calls to ima_log_string()
Signed-off-by: default avatarMimi Zohar <zohar@us.ibm.com>
Signed-off-by: default avatarDmitry Kasatkin <dmitry.kasatkin@intel.com>
      07f6a794
    • Mimi Zohar's avatar
      ima: integrity appraisal extension · 2fe5d6de
      Mimi Zohar authored 
      IMA currently maintains an integrity measurement list used to assert the
integrity of the running system to a third party.  The IMA-appraisal
extension adds local integrity validation and enforcement of the
measurement against a "good" value stored as an extended attribute
'security.ima'.  The initial methods for validating 'security.ima' are
hashed based, which provides file data integrity, and digital signature
based, which in addition to providing file data integrity, provides
authenticity.

This patch creates and maintains the 'security.ima' xattr, containing
the file data hash measurement.  Protection of the xattr is provided by
EVM, if enabled and configured.

Based on policy, IMA calls evm_verifyxattr() to verify a file's metadata
integrity and, assuming success, compares the file's current hash value
with the one stored as an extended attribute in 'security.ima'.

Changelov v4:
- changed iint cache flags to hex values

Changelog v3:
- change appraisal default for filesystems without xattr support to fail

Changelog v2:
- fix audit msg 'res' value
- removed unused 'ima_appraise=' values

Changelog v1:
- removed unused iint mutex (Dmitry Kasatkin)
- setattr hook must not reset appraised (Dmitry Kasatkin)
- evm_verifyxattr() now differentiates between no 'security.evm' xattr
  (INTEGRITY_NOLABEL) and no EVM 'protected' xattrs included in the
  'security.evm' (INTEGRITY_NOXATTRS).
- replace hash_status with ima_status (Dmitry Kasatkin)
- re-initialize slab element ima_status on free (Dmitry Kasatkin)
- include 'security.ima' in EVM if CONFIG_IMA_APPRAISE, not CONFIG_IMA
- merged half "ima: ima_must_appraise_or_measure API change" (Dmitry Kasatkin)
- removed unnecessary error variable in process_measurement() (Dmitry Kasatkin)
- use ima_inode_post_setattr() stub function, if IMA_APPRAISE not configured
  (moved ima_inode_post_setattr() to ima_appraise.c)
- make sure ima_collect_measurement() can read file

Changelog:
- add 'iint' to evm_verifyxattr() call (Dimitry Kasatkin)
- fix the race condition between chmod, which takes the i_mutex and then
  iint->mutex, and ima_file_free() and process_measurement(), which take
  the locks in the reverse order, by eliminating iint->mutex. (Dmitry Kasatkin)
- cleanup of ima_appraise_measurement() (Dmitry Kasatkin)
- changes as a result of the iint not allocated for all regular files, but
  only for those measured/appraised.
- don't try to appraise new/empty files
- expanded ima_appraisal description in ima/Kconfig
- IMA appraise definitions required even if IMA_APPRAISE not enabled
- add return value to ima_must_appraise() stub
- unconditionally set status = INTEGRITY_PASS *after* testing status,
  not before.  (Found by Joe Perches)
Signed-off-by: default avatarMimi Zohar <zohar@us.ibm.com>
Signed-off-by: default avatarDmitry Kasatkin <dmitry.kasatkin@intel.com>
      2fe5d6de
    • Mimi Zohar's avatar
      vfs: move ima_file_free before releasing the file · 4199d35c
      Mimi Zohar authored 
      ima_file_free(), called on __fput(), currently flags files that have
changed, so that the file is re-measured.  For appraising a files's
integrity, the file's hash must be re-calculated and stored in the
'security.ima' xattr to reflect any changes.

This patch moves the ima_file_free() call to before releasing the file
in preparation of ima-appraisal measuring the file and updating the
'security.ima' xattr.
Signed-off-by: default avatarMimi Zohar <zohar@us.ibm.com>
Acked-by: default avatarSerge Hallyn <serge.hallyn@ubuntu.com>
Acked-by: default avatarDmitry Kasatkin <dmitry.kasatkin@intel.com>
      4199d35c
    • Mimi Zohar's avatar
      vfs: extend vfs_removexattr locking · 2ab51f37
      Mimi Zohar authored 
      This patch takes the i_mutex lock before security_inode_removexattr(),
instead of after, in preparation of calling ima_inode_removexattr().
Signed-off-by: default avatarMimi Zohar <zohar@us.ibm.com>
Signed-off-by: default avatarDmitry Kasatkin <dmitry.kasatkin@nokia.com>
      2ab51f37
    • Kees Cook's avatar
      Yama: handle 32-bit userspace prctl · 2e4930eb
      Kees Cook authored 
      When running a 64-bit kernel and receiving prctls from a 32-bit
userspace, the "-1" used as an unsigned long will end up being
misdetected. The kernel is looking for 0xffffffffffffffff instead of
0xffffffff. Since prctl lacks a distinct compat interface, Yama needs
to handle this translation itself. As such, support either value as
meaning PR_SET_PTRACER_ANY, to avoid breaking the ABI for 64-bit.
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Acked-by: default avatarJohn Johansen <john.johansen@canonical.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarJames Morris <james.l.morris@oracle.com>
      2e4930eb
  5. 05 Sep, 2012 1 commit
  7. 04 Sep, 2012 1 commit
  9. 22 Aug, 2012 13 commits
  11. 17 Aug, 2012 1 commit
  13. 16 Aug, 2012 11 commits
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