linux-toradex.git/security/integrity/ima/ima_policy.c, branch v4.0-rc1

ima: require signature based appraisal

2014-11-18T04:12:01+00:00

This patch provides CONFIG_IMA_APPRAISE_SIGNED_INIT kernel configuration
option to force IMA appraisal using signatures. This is useful, when EVM
key is not initialized yet and we want securely initialize integrity or
any other functionality.

It forces embedded policy to require signature. Signed initialization
script can initialize EVM key, update the IMA policy and change further
requirement of everything to be signed.

Changes in v3:
* kernel parameter fixed to configuration option in the patch description

Changes in v2:
* policy change of this patch separated from the key loading patch

Signed-off-by: Dmitry Kasatkin 
Signed-off-by: Mimi Zohar

ima: use atomic bit operations to protect policy update interface

2014-10-12T03:33:02+00:00

The current implementation uses an atomic counter to provide exclusive
access to the sysfs 'policy' entry to update the IMA policy. While it is
highly unlikely, the usage of a counter might potentially allow another
process to overflow the counter, open the interface and insert additional
rules into the policy being loaded.

This patch replaces using an atomic counter with atomic bit operations
which is more reliable and a widely used method to provide exclusive access.

As bit operation keep the interface locked after successful update, it makes
it unnecessary to verify if the default policy was set or not during parsing
and interface closing. This patch also removes that code.

Changes in v3:
* move audit log message to ima_relead_policy() to report successful and
  unsuccessful result
* unnecessary comment removed

Changes in v2:
* keep interface locked after successful policy load as in original design
* remove sysfs entry as in original design

Signed-off-by: Dmitry Kasatkin 
Signed-off-by: Mimi Zohar

ima: ignore empty and with whitespaces policy lines

2014-10-12T03:29:19+00:00

Empty policy lines cause parsing failures which is, especially
for new users, hard to spot. This patch prevents it.

Changes in v2:
* strip leading blanks and tabs in rules to prevent parsing failures

Signed-off-by: Dmitry Kasatkin 
Signed-off-by: Mimi Zohar

ima: no need to allocate entry for comment

2014-10-12T03:28:07+00:00

If a rule is a comment, there is no need to allocate an entry.
Move the checking for comments before allocating the entry.

Signed-off-by: Dmitry Kasatkin 
Signed-off-by: Mimi Zohar

ima: added ima_policy_flag variable

2014-09-17T20:39:36+00:00

This patch introduces the new variable 'ima_policy_flag', whose bits
are set depending on the action of the current policy rules. Only the
flags IMA_MEASURE, IMA_APPRAISE and IMA_AUDIT are set.

The new variable will be used to improve performance by skipping the
unnecessary execution of IMA code if the policy does not contain rules
with the above actions.

Changes in v6 (Roberto Sassu)
* do not check 'ima_initialized' before calling ima_update_policy_flag()
  in ima_update_policy() (suggested by Dmitry)
* calling ima_update_policy_flag() moved to init_ima to co-locate with
  ima_initialized (Dmitry)
* add/revise comments (Mimi)

Changes in v5 (Roberto Sassu)
* reset IMA_APPRAISE flag in 'ima_policy_flag' if 'ima_appraise' is set
  to zero (reported by Dmitry)
* update 'ima_policy_flag' only if IMA initialization is successful
  (suggested by Mimi and Dmitry)
* check 'ima_policy_flag' instead of 'ima_initialized'
  (suggested by Mimi and Dmitry)

Signed-off-by: Roberto Sassu 
Signed-off-by: Dmitry Kasatkin 
Signed-off-by: Mimi Zohar

ima: add support for measuring and appraising firmware

2014-07-25T18:47:46+00:00

The "security: introduce kernel_fw_from_file hook" patch defined a
new security hook to evaluate any loaded firmware that wasn't built
into the kernel.

This patch defines ima_fw_from_file(), which is called from the new
security hook, to measure and/or appraise the loaded firmware's
integrity.

Signed-off-by: Mimi Zohar 
Signed-off-by: Kees Cook

audit: fix dangling keywords in integrity ima message output

2014-07-17T13:35:10+00:00

Replace spaces in op keyword labels in log output since userspace audit tools
can't parse orphaned keywords.

Reported-by: Steve Grubb 
Signed-off-by: Richard Guy Briggs 
Signed-off-by: Mimi Zohar

ima: audit log files opened with O_DIRECT flag

2014-06-03T19:21:50+00:00

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 
Cc:

integrity: fix checkpatch errors

2014-03-07T17:15:45+00:00

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

2014-03-07T17:15:44+00:00

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