Commit Graph

456853 Commits

Author SHA1 Message Date
Dmitry Kasatkin
c57782c13e ima: require signature based appraisal
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 <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
2014-11-17 23:12:01 -05:00
Dmitry Kasatkin
c9cd2ce2bc integrity: provide a hook to load keys when rootfs is ready
Keys can only be loaded once the rootfs is mounted. Initcalls
are not suitable for that. This patch defines a special hook
to load the x509 public keys onto the IMA keyring, before
attempting to access any file. The keys are required for
verifying the file's signature. The hook is called after the
root filesystem is mounted and before the kernel calls 'init'.

Changes in v3:
* added more explanation to the patch description (Mimi)

Changes in v2:
* Hook renamed as 'integrity_load_keys()' to handle both IMA and EVM
  keys by integrity subsystem.
* Hook patch moved after defining loading functions

Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
2014-11-17 23:12:01 -05:00
Dmitry Kasatkin
fd5f4e9054 ima: load x509 certificate from the kernel
Define configuration option to load X509 certificate into the
IMA trusted kernel keyring. It implements ima_load_x509() hook
to load X509 certificate into the .ima trusted kernel keyring
from the root filesystem.

Changes in v3:
* use ima_policy_flag in ima_get_action()
  ima_load_x509 temporarily clears ima_policy_flag to disable
  appraisal to load key. Use it to skip appraisal rules.
* Key directory path changed to /etc/keys (Mimi)
* Expand IMA_LOAD_X509 Kconfig help

Changes in v2:
* added '__init'
* use ima_policy_flag to disable appraisal to load keys

Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
2014-11-17 23:12:00 -05:00
Dmitry Kasatkin
65d543b233 integrity: provide a function to load x509 certificate from the kernel
Provide the function to load x509 certificates from the kernel into the
integrity kernel keyring.

Changes in v2:
* configuration option removed
* function declared as '__init'

Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
2014-11-17 23:11:59 -05:00
Dmitry Kasatkin
e3c4abbfa9 integrity: define a new function integrity_read_file()
This patch defines a new function called integrity_read_file()
to read file from the kernel into a buffer. Subsequent patches
will read a file containing the public keys and load them onto
the IMA keyring.

This patch moves and renames ima_kernel_read(), the non-security
checking version of kernel_read(), to integrity_kernel_read().

Changes in v3:
* Patch descriptions improved (Mimi)
* Add missing cast (kbuild test robot)

Changes in v2:
* configuration option removed
* function declared as '__init'

Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
2014-11-17 23:09:18 -05:00
Roberto Sassu
c2426d2ad5 ima: added support for new kernel cmdline parameter ima_template_fmt
This patch allows users to provide a custom template format through the
new kernel command line parameter 'ima_template_fmt'. If the supplied
format is not valid, IMA uses the default template descriptor.

Changelog:
 - v3:
   - added check for 'fields' and 'num_fields' in
     template_desc_init_fields() (suggested by Mimi Zohar)

 - v2:
   - using template_desc_init_fields() to validate a format string
     (Roberto Sassu)
   - updated documentation by stating that only the chosen template
     descriptor is initialized (Roberto Sassu)

 - v1:
   - simplified code of ima_template_fmt_setup()
     (Roberto Sassu, suggested by Mimi Zohar)

Signed-off-by: Roberto Sassu <roberto.sassu@polito.it>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
2014-10-13 08:39:02 -04:00
Roberto Sassu
1bd7face74 ima: allocate field pointers array on demand in template_desc_init_fields()
The allocation of a field pointers array is moved at the end of
template_desc_init_fields() and done only if the value of the 'fields'
and 'num_fields' parameters is not NULL. For just validating a template
format string, retrieved template field pointers are placed in a temporary
array.

Changelog:
 - v3:
   - do not check in this patch if 'fields' and 'num_fields' are NULL
     (suggested by Mimi Zohar)

Signed-off-by: Roberto Sassu <roberto.sassu@polito.it>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
2014-10-13 08:39:02 -04:00
Roberto Sassu
9f3166b8ca ima: don't allocate a copy of template_fmt in template_desc_init_fields()
This patch removes the allocation of a copy of 'template_fmt', needed for
iterating over all fields in the passed template format string. The removal
was possible by replacing strcspn(), which modifies the passed string,
with strchrnul(). The currently processed template field is copied in
a temporary variable.

The purpose of this change is use template_desc_init_fields() in two ways:
for just validating a template format string (the function should work
if called by a setup function, when memory cannot be allocated), and for
actually initializing a template descriptor. The implementation of this
feature will be complete with the next patch.

Changelog:
 - v3:
   - added 'goto out' in template_desc_init_fields() to free allocated
     memory if a template field length is not valid (suggested by
     Mimi Zohar)

Signed-off-by: Roberto Sassu <roberto.sassu@polito.it>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
2014-10-13 08:39:01 -04:00
Roberto Sassu
7dbdb4206b ima: display template format in meas. list if template name length is zero
With the introduction of the 'ima_template_fmt' kernel cmdline parameter,
a user can define a new template descriptor with custom format. However,
in this case, userspace tools will be unable to parse the measurements
list because the new template is unknown. For this reason, this patch
modifies the current IMA behavior to display in the list the template
format instead of the name (only if the length of the latter is zero)
so that a tool can extract needed information if it can handle listed
fields.

This patch also correctly displays the error log message in
ima_init_template() if the selected template cannot be initialized.

Changelog:
 - v3:
   - check the first byte of 'e->template_desc->name' instead of using
     strlen() in ima_fs.c (suggested by Mimi Zohar)

 - v2:
   - print the template format in ima_init_template(), if the selected
     template is custom (Roberto Sassu)

 - v1:
   - fixed patch description (Roberto Sassu, suggested by Mimi Zohar)
   - set 'template_name' variable in ima_fs.c only once
     (Roberto Sassu, suggested by Mimi Zohar)

Signed-off-by: Roberto Sassu <roberto.sassu@polito.it>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
2014-10-13 08:39:01 -04:00
Roberto Sassu
71fed2eee0 ima: added error messages to template-related functions
This patch adds some error messages to inform users about the following
events: template descriptor not found, invalid template descriptor,
template field not found and template initialization failed.

Changelog:
 - v2:
   - display an error message if the format string contains too many
     fields (Roberto Sassu)

Signed-off-by: Roberto Sassu <roberto.sassu@polito.it>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
2014-10-13 08:39:01 -04:00
Dmitry Kasatkin
0716abbb58 ima: use atomic bit operations to protect policy update interface
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 <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
2014-10-11 23:33:02 -04:00
Dmitry Kasatkin
7178784f0a ima: ignore empty and with whitespaces policy lines
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 <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
2014-10-11 23:29:19 -04:00
Dmitry Kasatkin
272a6e90ff ima: no need to allocate entry for comment
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 <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
2014-10-11 23:28:07 -04:00
Dmitry Kasatkin
78bb5d0b4f ima: report policy load status
Audit messages are rate limited, often causing the policy update
info to not be visible.  Report policy loading status also using
pr_info.

Changes in v2:
* reporting moved to ima_release_policy to notice parsing errors
* reporting both completed and failed status

Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
2014-10-11 23:25:25 -04:00
Dmitry Kasatkin
456f5fd3f6 ima: use path names cache
__getname() uses slab allocation which is faster than kmalloc.
Make use of it.

Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
2014-10-07 14:32:54 -04:00
Dmitry Kasatkin
c2baec7ffa evm: skip replacing EVM signature with HMAC on read-only filesystem
If filesystem is mounted read-only or file is immutable, updating
xattr will fail. This is a usual case during early boot until
filesystem is remount read-write. This patch verifies conditions
to skip unnecessary attempt to calculate HMAC and set xattr.

Changes in v2:
* indention changed according to Lindent (requested by Mimi)

Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
2014-10-07 14:32:53 -04:00
Dmitry Kasatkin
d16a8585d3 integrity: add missing '__init' keyword for integrity_init_keyring()
integrity_init_keyring() is used only from kernel '__init'
functions. Add it there as well.

Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
2014-10-07 14:32:53 -04:00
Dmitry Kasatkin
0f34a0060a ima: check ima_policy_flag in the ima_file_free() hook
This patch completes the switching to the 'ima_policy_flag' variable
in the checks at the beginning of IMA functions, starting with the
commit a756024e.

Checking 'iint_initialized' is completely unnecessary, because
S_IMA flag is unset if iint was not allocated. At the same time
the integrity cache is allocated with SLAB_PANIC and the kernel will
panic if the allocation fails during kernel initialization. So on
a running system iint_initialized is always true and can be removed.

Changes in v3:
* not limiting test to IMA_APPRAISE (spotted by Roberto Sassu)

Changes in v2:
* 'iint_initialized' removal patch merged to this patch (requested
   by Mimi)

Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Acked-by: Roberto Sassu <roberto.sassu@polito.it>
2014-10-07 14:32:52 -04:00
Dmitry Kasatkin
594081ee71 integrity: do zero padding of the key id
Latest KEYS code return error if hexadecimal string length id odd.
Fix it.

Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: David Howells <dhowells@redhat.com>
2014-10-06 17:33:27 +01:00
Dmitry Kasatkin
d401658985 KEYS: output last portion of fingerprint in /proc/keys
Previous version of KEYS used to output last 4 bytes of fingerprint.
Now it outputs 8 last bytes of raw subject, which does not make any
visual meaning at all. This patch restores old behavior.

Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: David Howells <dhowells@redhat.com>
2014-10-06 17:33:27 +01:00
Dmitry Kasatkin
7a224e783a KEYS: strip 'id:' from ca_keyid
The 'id:' prefix must be stripped for asymmetric_key_hex_to_key_id() to be
able to process ca_keyid.

Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: David Howells <dhowells@redhat.com>
2014-10-06 17:33:27 +01:00
Dmitry Kasatkin
8dd609805b KEYS: use swapped SKID for performing partial matching
Earlier KEYS code used pure subject key identifiers (fingerprint)
for searching keys. Latest merged code removed that and broke
compatibility with integrity subsytem signatures and original
format of module signatures.

This patch returns back partial matching on SKID.

Reported-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: David Howells <dhowells@redhat.com>
2014-10-06 16:56:08 +01:00
Dmitry Kasatkin
f1b731dbc2 KEYS: Restore partial ID matching functionality for asymmetric keys
Bring back the functionality whereby an asymmetric key can be matched with a
partial match on one of its IDs.

Whilst we're at it, allow for the possibility of having an increased number of
IDs.

Reported-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: David Howells <dhowells@redhat.com>
2014-10-06 15:21:05 +01:00
David Howells
dd2f6c4481 X.509: If available, use the raw subjKeyId to form the key description
Module signing matches keys by comparing against the key description exactly.
However, the way the key description gets constructed got changed to be
composed of the subject name plus the certificate serial number instead of the
subject name and the subjectKeyId.  I changed this to avoid problems with
certificates that don't *have* a subjectKeyId.

Instead, if available, use the raw subjectKeyId to form the key description
and only use the serial number if the subjectKeyId doesn't exist.

Reported-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: David Howells <dhowells@redhat.com>
2014-10-03 16:17:02 +01:00
Dmitry Kasatkin
40b50e80c5 KEYS: handle error code encoded in pointer
If hexlen is odd then function returns an error.
Use IS_ERR to check for error, otherwise invalid pointer
is used and kernel gives oops:

[  132.816522] BUG: unable to handle kernel paging request at
ffffffffffffffea
[  132.819902] IP: [<ffffffff812bfc20>] asymmetric_key_id_same+0x14/0x36
[  132.820302] PGD 1a12067 PUD 1a14067 PMD 0
[  132.820302] Oops: 0000 [#1] SMP
[  132.820302] Modules linked in: bridge(E) stp(E) llc(E) evdev(E)
serio_raw(E) i2c_piix4(E) button(E) fuse(E)
[  132.820302] CPU: 0 PID: 2993 Comm: cat Tainted: G            E
3.16.0-kds+ #2847
[  132.820302] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[  132.820302] task: ffff88004249a430 ti: ffff880056640000 task.ti:
ffff880056640000
[  132.820302] RIP: 0010:[<ffffffff812bfc20>]  [<ffffffff812bfc20>]
asymmetric_key_id_same+0x14/0x36
[  132.820302] RSP: 0018:ffff880056643930  EFLAGS: 00010246
[  132.820302] RAX: 0000000000000000 RBX: ffffffffffffffea RCX:
ffff880056643ae0
[  132.820302] RDX: 000000000000005e RSI: ffffffffffffffea RDI:
ffff88005bac9300
[  132.820302] RBP: ffff880056643948 R08: 0000000000000003 R09:
00000007504aa01a
[  132.820302] R10: 0000000000000000 R11: 0000000000000000 R12:
ffff88005d68ca40
[  132.820302] R13: 0000000000000101 R14: 0000000000000000 R15:
ffff88005bac5280
[  132.820302] FS:  00007f67a153c740(0000) GS:ffff88005da00000(0000)
knlGS:0000000000000000
[  132.820302] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[  132.820302] CR2: ffffffffffffffea CR3: 000000002e663000 CR4:
00000000000006f0
[  132.820302] Stack:
[  132.820302]  ffffffff812bfc66 ffff880056643ae0 ffff88005bac5280
ffff880056643958
[  132.820302]  ffffffff812bfc9d ffff880056643980 ffffffff812971d9
ffff88005ce930c1
[  132.820302]  ffff88005ce930c0 0000000000000000 ffff8800566439c8
ffffffff812fb753
[  132.820302] Call Trace:
[  132.820302]  [<ffffffff812bfc66>] ? asymmetric_match_key_ids+0x24/0x42
[  132.820302]  [<ffffffff812bfc9d>] asymmetric_key_cmp+0x19/0x1b
[  132.820302]  [<ffffffff812971d9>] keyring_search_iterator+0x74/0xd7
[  132.820302]  [<ffffffff812fb753>] assoc_array_subtree_iterate+0x67/0xd2
[  132.820302]  [<ffffffff81297165>] ? key_default_cmp+0x20/0x20
[  132.820302]  [<ffffffff812fbaa1>] assoc_array_iterate+0x19/0x1e
[  132.820302]  [<ffffffff81297332>] search_nested_keyrings+0xf6/0x2b6
[  132.820302]  [<ffffffff810728da>] ? sched_clock_cpu+0x91/0xa2
[  132.820302]  [<ffffffff810860d2>] ? mark_held_locks+0x58/0x6e
[  132.820302]  [<ffffffff810a137d>] ? current_kernel_time+0x77/0xb8
[  132.820302]  [<ffffffff81297871>] keyring_search_aux+0xe1/0x14c
[  132.820302]  [<ffffffff812977fc>] ? keyring_search_aux+0x6c/0x14c
[  132.820302]  [<ffffffff8129796b>] keyring_search+0x8f/0xb6
[  132.820302]  [<ffffffff812bfc84>] ? asymmetric_match_key_ids+0x42/0x42
[  132.820302]  [<ffffffff81297165>] ? key_default_cmp+0x20/0x20
[  132.820302]  [<ffffffff812ab9e3>] asymmetric_verify+0xa4/0x214
[  132.820302]  [<ffffffff812ab90e>] integrity_digsig_verify+0xb1/0xe2
[  132.820302]  [<ffffffff812abe41>] ? evm_verifyxattr+0x6a/0x7a
[  132.820302]  [<ffffffff812b0390>] ima_appraise_measurement+0x160/0x370
[  132.820302]  [<ffffffff81161db2>] ? d_absolute_path+0x5b/0x7a
[  132.820302]  [<ffffffff812ada30>] process_measurement+0x322/0x404

Reported-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: David Howells <dhowells@redhat.com>
2014-10-03 13:41:51 +01:00
James Morris
c867d07e3c Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity into next 2014-10-02 19:47:23 +10:00
James Morris
858f61c429 Merge branch 'next' of git://git.infradead.org/users/pcmoore/selinux into next 2014-10-01 00:45:26 +10:00
James Morris
6c8ff877cd Merge commit 'v3.16' into next 2014-10-01 00:44:04 +10:00
Richard Guy Briggs
4093a84439 selinux: normalize audit log formatting
Restructure to keyword=value pairs without spaces.  Drop superfluous words in
text.  Make invalid_context a keyword.  Change result= keyword to seresult=.

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
[Minor rewrite to the patch subject line]
Signed-off-by: Paul Moore <pmoore@redhat.com>
2014-09-22 17:02:10 -04:00
Richard Guy Briggs
e173fb2646 selinux: cleanup error reporting in selinux_nlmsg_perm()
Convert audit_log() call to WARN_ONCE().

Rename "type=" to nlmsg_type=" to avoid confusion with the audit record
type.

Added "protocol=" to help track down which protocol (NETLINK_AUDIT?) was used
within the netlink protocol family.

Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
[Rewrote the patch subject line]
Signed-off-by: Paul Moore <pmoore@redhat.com>
2014-09-22 15:50:08 -04:00
James Morris
35e1efd25a Merge tag 'keys-next-20140922' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs into next 2014-09-22 22:54:56 +10:00
David Howells
d1ac554045 KEYS: Check hex2bin()'s return when generating an asymmetric key ID
As it stands, the code to generate an asymmetric key ID prechecks the hex
string it is given whilst determining the length, before it allocates the
buffer for hex2bin() to translate into - which mean that checking the result of
hex2bin() is redundant.

Unfortunately, hex2bin() is marked as __must_check, which means that the
following warning may be generated if the return value isn't checked:

	crypto/asymmetric_keys/asymmetric_type.c: In function
	asymmetric_key_hex_to_key_id:
	crypto/asymmetric_keys/asymmetric_type.c:110: warning: ignoring return
	value of hex2bin, declared with attribute warn_unused_result

The warning can't be avoided by casting the result to void.

Instead, use strlen() to check the length of the string and ignore the fact
that the string might not be entirely valid hex until after the allocation has
been done - in which case we can use the result of hex2bin() for this.

Signed-off-by: David Howells <dhowells@redhat.com>
2014-09-22 00:02:01 +01:00
Roberto Sassu
1b68bdf9cd ima: detect violations for mmaped files
This patch fixes the detection of the 'open_writers' violation for mmaped
files.

before) an 'open_writers' violation is detected if the policy contains
        a rule with the criteria: func=FILE_CHECK mask=MAY_READ

after) an 'open_writers' violation is detected if the current event
       matches one of the policy rules.

With the old behaviour, the 'open_writers' violation is not detected
in the following case:

policy:
measure func=FILE_MMAP mask=MAY_EXEC

steps:
1) open a shared library for writing
2) execute a binary that links that shared library
3) during the binary execution, modify the shared library and save
   the change

result:
the 'open_writers' violation measurement is not present in the IMA list.

Only binaries executed are protected from writes. For libraries mapped
in memory there is the flag MAP_DENYWRITE for this purpose, but according
to the output of 'man mmap', the mmap flag is ignored.

Since ima_rdwr_violation_check() is now called by process_measurement()
the information about if the inode must be measured is already provided
by ima_get_action(). Thus the unnecessary function ima_must_measure()
has been removed.

Changes in v3 (Dmitry Kasatkin):
- Violation for MMAP_CHECK function are verified since this patch
- Changed patch description a bit

Signed-off-by: Roberto Sassu <roberto.sassu@polito.it>
Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
2014-09-18 10:04:12 -04:00
Roberto Sassu
f7a859ff73 ima: fix race condition on ima_rdwr_violation_check and process_measurement
This patch fixes a race condition between two functions that try to access
the same inode. Since the i_mutex lock is held and released separately
in the two functions, there may be the possibility that a violation is
not correctly detected.

Suppose there are two processes, A (reader) and B (writer), if the
following sequence happens:

A: ima_rdwr_violation_check()
B: ima_rdwr_violation_check()
B: process_measurement()
B: starts writing the inode
A: process_measurement()

the ToMToU violation (a reader may be accessing a content different from
that measured, due to a concurrent modification by a writer) will not be
detected. To avoid this issue, the violation check and the measurement
must be done atomically.

This patch fixes the problem by moving the violation check inside
process_measurement() when the i_mutex lock is held. Differently from
the old code, the violation check is executed also for the MMAP_CHECK
hook (other than for FILE_CHECK). This allows to detect ToMToU violations
that are possible because shared libraries can be opened for writing
while they are in use (according to the output of 'man mmap', the mmap()
flag MAP_DENYWRITE is ignored).

Changes in v5 (Roberto Sassu):
* get iint if action is not zero
* exit process_measurement() after the violation check if action is zero
* reverse order process_measurement() exit cleanup (Mimi)

Changes in v4 (Dmitry Kasatkin):
* iint allocation is done before calling ima_rdrw_violation_check()
  (Suggested-by Mimi)
* do not check for violations if the policy does not contain 'measure'
  rules (done by Roberto Sassu)

Changes in v3 (Dmitry Kasatkin):
* no violation checking for MMAP_CHECK function in this patch
* remove use of filename from violation
* removes checking if ima is enabled from ima_rdrw_violation_check
* slight style change

Suggested-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Roberto Sassu <roberto.sassu@polito.it>
Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
2014-09-18 10:03:55 -04:00
James Morris
6f98e89288 Merge branch 'smack-for-3.18' of git://git.gitorious.org/smack-next/kernel into next 2014-09-18 23:52:46 +10:00
Roberto Sassu
a756024efe ima: added ima_policy_flag variable
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 <roberto.sassu@polito.it>
Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
2014-09-17 16:39:36 -04:00
Roberto Sassu
be39ffc2fe ima: return an error code from ima_add_boot_aggregate()
This patch modifies ima_add_boot_aggregate() to return an error code.
This way we can determine if all the initialization procedures have
been executed successfully.

Signed-off-by: Roberto Sassu <roberto.sassu@polito.it>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
2014-09-17 16:15:42 -04:00
Dmitry Kasatkin
2faa6ef3b2 ima: provide 'ima_appraise=log' kernel option
The kernel boot parameter "ima_appraise" currently defines 'off',
'enforce' and 'fix' modes.  When designing a policy and labeling
the system, access to files are either blocked in the default
'enforce' mode or automatically fixed in the 'fix' mode.  It is
beneficial to be able to run the system in a logging only mode,
without fixing it, in order to properly analyze the system. This
patch adds a 'log' mode to run the system in a permissive mode and
log the appraisal results.

Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
2014-09-17 16:14:23 -04:00
Dmitry Kasatkin
31b70f6632 ima: move keyring initialization to ima_init()
ima_init() is used as a single place for all initializations.
Experimental keyring patches used the 'late_initcall' which was
co-located with the late_initcall(init_ima). When the late_initcall
for the keyring initialization was abandoned, initialization moved
to init_ima, though it would be more logical to move it to ima_init,
where the rest of the initialization is done. This patch moves the
keyring initialization to ima_init() as a preparatory step for
loading the keys which will be added to ima_init() in following
patches.

Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
2014-09-17 16:10:59 -04:00
David Howells
d3e4f41973 PKCS#7 changes for next
-----BEGIN PGP SIGNATURE-----
 Version: GnuPG v1
 
 iQIVAwUAVBhnNxOxKuMESys7AQIlzA/6Ai9tUQQweoKvbVMyByF5AxsCvLeLZK+h
 uoi0vs5Lwq29Eb+ldvwgOlEveqy0+V3pdIiBbRflqLrPx08IP+0JbD6yn9rfXbmz
 eyCSb/DGBPoA6Mo2lvcLzvFyFbScCW2vQkX/el+1cOR4aYMryAWCHY8w+IkR2e27
 aKCSv5mpL2fA/zCGKZnsVRx0izukCPn7p6xvFQz5CQLh67zVNkFLsCzDdkmL4ml7
 FmZyrWFJhGtoEyyqO/oiz2La5iiMQjJQPdrgjq+E11BVxc4auPvpxrk/ZbJR/O4J
 KQ409l9EtbM4hS9CU2F3ZkAlhCDUJruS9vLD/FKiSUYkgHIHlUIk/38Ke+KPGFp0
 NpnCiYSU529PYvSoOuLNPxH6CvEF/PVsOuPr1ryiPpf7VdTJWvNYmJ999cdl4fIp
 GLIkoKchlCIf7SlonvFpevJf3v29bXfbiQEbxDEZgdtqkN9ZIA1W90CmnZyHvJUf
 5Acs1pDjZEpZIKrlDpi3N1usAX2vduDHxaGSY/FRevSshu9NELyo9dzwjGIenrAQ
 TU0q8NzVrikkJJjP0XUuJpDAz+gdwWfTc+Dxoi4KdgV0cazeRj79Hdl4a3i5jnp6
 8Ck351gh1Wfaz5IaFM0hT9V1XYTZ5kAE6WwTZy39/VtAPl3XiGK/ll1qRHRIvX0n
 tv8fhxJpfNo=
 =Pvcv
 -----END PGP SIGNATURE-----

Merge tag 'keys-pkcs7-20140916' into keys-next

Changes for next to improve the matching of asymmetric keys and to improve the
handling of PKCS#7 certificates:

 (1) Provide a method to preparse the data supplied for matching a key.  This
     permits they key type to extract out the bits it needs for matching once
     only.

     Further, the type of search (direct lookup or iterative) can be set and
     the function used to actually check the match can be set by preparse
     rather than being hard coded for the type.

 (2) Improves asymmetric keys identification.

     Keys derived from X.509 certs now get labelled with IDs derived from their
     issuer and certificate number (required to match PKCS#7) and from their
     SKID and subject (required to match X.509).

     IDs are now binary and match criterion preparsing is provided so that
     criteria can be turned into binary blobs to make matching faster.

 (3) Improves PKCS#7 message handling to permit PKCS#7 messages without X.509
     cert lists to be matched to trusted keys, thereby allowing minimally sized
     PKCS#7 certs to be used.

 (4) Improves PKCS#7 message handling to better handle certificate chains that
     are broken due to unsupported crypto that can otherwise by used to
     intersect a trust keyring.

These must go on top of the PKCS#7 parser cleanup fixes.

Signed-off-by: David Howells <dhowells@redhat.com>
2014-09-16 17:38:07 +01:00
David Howells
757932e6da PKCS#7: Handle PKCS#7 messages that contain no X.509 certs
The X.509 certificate list in a PKCS#7 message is optional.  To save space, we
can omit the inclusion of any X.509 certificates if we are sure that we can
look the relevant public key up by the serial number and issuer given in a
signed info block.

This also supports use of a signed info block for which we can't find a
matching X.509 cert in the certificate list, though it be populated.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
2014-09-16 17:36:17 +01:00
David Howells
4155942000 PKCS#7: Better handling of unsupported crypto
Provide better handling of unsupported crypto when verifying a PKCS#7 message.
If we can't bridge the gap between a pair of X.509 certs or between a signed
info block and an X.509 cert because it involves some crypto we don't support,
that's not necessarily the end of the world as there may be other ways points
at which we can intersect with a ring of trusted keys.

Instead, only produce ENOPKG immediately if all the signed info blocks in a
PKCS#7 message require unsupported crypto to bridge to the first X.509 cert.
Otherwise, we defer the generation of ENOPKG until we get ENOKEY during trust
validation.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
2014-09-16 17:36:15 +01:00
David Howells
46963b774d KEYS: Overhaul key identification when searching for asymmetric keys
Make use of the new match string preparsing to overhaul key identification
when searching for asymmetric keys.  The following changes are made:

 (1) Use the previously created asymmetric_key_id struct to hold the following
     key IDs derived from the X.509 certificate or PKCS#7 message:

	id: serial number + issuer
	skid: subjKeyId + subject
	authority: authKeyId + issuer

 (2) Replace the hex fingerprint attached to key->type_data[1] with an
     asymmetric_key_ids struct containing the id and the skid (if present).

 (3) Make the asymmetric_type match data preparse select one of two searches:

     (a) An iterative search for the key ID given if prefixed with "id:".  The
     	 prefix is expected to be followed by a hex string giving the ID to
     	 search for.  The criterion key ID is checked against all key IDs
     	 recorded on the key.

     (b) A direct search if the key ID is not prefixed with "id:".  This will
     	 look for an exact match on the key description.

 (4) Make x509_request_asymmetric_key() take a key ID.  This is then converted
     into "id:<hex>" and passed into keyring_search() where match preparsing
     will turn it back into a binary ID.

 (5) X.509 certificate verification then takes the authority key ID and looks
     up a key that matches it to find the public key for the certificate
     signature.

 (6) PKCS#7 certificate verification then takes the id key ID and looks up a
     key that matches it to find the public key for the signed information
     block signature.

Additional changes:

 (1) Multiple subjKeyId and authKeyId values on an X.509 certificate cause the
     cert to be rejected with -EBADMSG.

 (2) The 'fingerprint' ID is gone.  This was primarily intended to convey PGP
     public key fingerprints.  If PGP is supported in future, this should
     generate a key ID that carries the fingerprint.

 (3) Th ca_keyid= kernel command line option is now converted to a key ID and
     used to match the authority key ID.  Possibly this should only match the
     actual authKeyId part and not the issuer as well.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
2014-09-16 17:36:13 +01:00
David Howells
7901c1a8ef KEYS: Implement binary asymmetric key ID handling
Implement the first step in using binary key IDs for asymmetric keys rather
than hex string keys.

The previously added match data preparsing will be able to convert hex
criterion strings into binary which can then be compared more rapidly.

Further, we actually want more then one ID string per public key.  The problem
is that X.509 certs refer to other X.509 certs by matching Issuer + AuthKeyId
to Subject + SubjKeyId, but PKCS#7 messages match against X.509 Issuer +
SerialNumber.

This patch just provides facilities for a later patch to make use of.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
2014-09-16 17:36:11 +01:00
David Howells
f93b3cc7b1 KEYS: Update the keyrings documentation for match changes
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
2014-09-16 17:36:09 +01:00
David Howells
0c903ab64f KEYS: Make the key matching functions return bool
Make the key matching functions pointed to by key_match_data::cmp return bool
rather than int.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
2014-09-16 17:36:08 +01:00
David Howells
c06cfb08b8 KEYS: Remove key_type::match in favour of overriding default by match_preparse
A previous patch added a ->match_preparse() method to the key type.  This is
allowed to override the function called by the iteration algorithm.
Therefore, we can just set a default that simply checks for an exact match of
the key description with the original criterion data and allow match_preparse
to override it as needed.

The key_type::match op is then redundant and can be removed, as can the
user_match() function.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
2014-09-16 17:36:06 +01:00
David Howells
614d8c3901 KEYS: Remove key_type::def_lookup_type
Remove key_type::def_lookup_type as it's no longer used.  The information now
defaults to KEYRING_SEARCH_LOOKUP_DIRECT but may be overridden by
type->match_preparse().

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
2014-09-16 17:36:04 +01:00
David Howells
462919591a KEYS: Preparse match data
Preparse the match data.  This provides several advantages:

 (1) The preparser can reject invalid criteria up front.

 (2) The preparser can convert the criteria to binary data if necessary (the
     asymmetric key type really wants to do binary comparison of the key IDs).

 (3) The preparser can set the type of search to be performed.  This means
     that it's not then a one-off setting in the key type.

 (4) The preparser can set an appropriate comparator function.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
2014-09-16 17:36:02 +01:00
David Howells
53d91c5ce0 Provide a binary to hex conversion function
Provide a function to convert a buffer of binary data into an unterminated
ascii hex string representation of that data.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
2014-09-16 17:36:01 +01:00