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authorLinus Torvalds <torvalds@linux-foundation.org>2018-01-31 13:07:35 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2018-01-31 13:07:35 -0800
commit3c29548f87f9545f2f3c1cd1a784fae8ad2d53ba (patch)
treea6ee072fea6f32e40fad48319ddf3cc3eca53dcb /Documentation
parente1c70f32386c4984ed8ca1a7aedb9bbff9ed3414 (diff)
parent36447456e1cca853188505f2a964dbbeacfc7a7a (diff)
Merge branch 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security
Pull integrity updates from James Morris: "This contains a mixture of bug fixes, code cleanup, and new functionality. Of note is the integrity cache locking fix, file change detection, and support for a new EVM portable and immutable signature type. The re-introduction of the integrity cache lock (iint) fixes the problem of attempting to take the i_rwsem shared a second time, when it was previously taken exclusively. Defining atomic flags resolves the original iint/i_rwsem circular locking - accessing the file data vs. modifying the file metadata. Although it fixes the O_DIRECT problem as well, a subsequent patch is needed to remove the explicit O_DIRECT prevention. For performance reasons, detecting when a file has changed and needs to be re-measured, re-appraised, and/or re-audited, was limited to after the last writer has closed, and only if the file data has changed. Detecting file change is based on i_version. For filesystems that do not support i_version, remote filesystems, or userspace filesystems, the file was measured, appraised and/or audited once and never re-evaluated. Now local filesystems, which do not support i_version or are not mounted with the i_version option, assume the file has changed and are required to re-evaluate the file. This change does not address detecting file change on remote or userspace filesystems. Unlike file data signatures, which can be included and distributed in software packages (eg. rpm, deb), the existing EVM signature, which protects the file metadata, could not be included in software packages, as it includes file system specific information (eg. i_ino, possibly the UUID). This pull request defines a new EVM portable and immutable file metadata signature format, which can be included in software packages" * 'next-integrity' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security: ima/policy: fix parsing of fsuuid ima: Use i_version only when filesystem supports it integrity: remove unneeded initializations in integrity_iint_cache entries ima: log message to module appraisal error ima: pass filename to ima_rdwr_violation_check() ima: Fix line continuation format ima: support new "hash" and "dont_hash" policy actions ima: re-introduce own integrity cache lock EVM: Add support for portable signature format EVM: Allow userland to permit modification of EVM-protected metadata ima: relax requiring a file signature for new files with zero length
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/ABI/testing/evm54
-rw-r--r--Documentation/ABI/testing/ima_policy3
2 files changed, 37 insertions, 20 deletions
diff --git a/Documentation/ABI/testing/evm b/Documentation/ABI/testing/evm
index 9578247e1792..d12cb2eae9ee 100644
--- a/Documentation/ABI/testing/evm
+++ b/Documentation/ABI/testing/evm
@@ -14,30 +14,46 @@ Description:
generated either locally or remotely using an
asymmetric key. These keys are loaded onto root's
keyring using keyctl, and EVM is then enabled by
- echoing a value to <securityfs>/evm:
+ echoing a value to <securityfs>/evm made up of the
+ following bits:
- 1: enable HMAC validation and creation
- 2: enable digital signature validation
- 3: enable HMAC and digital signature validation and HMAC
- creation
+ Bit Effect
+ 0 Enable HMAC validation and creation
+ 1 Enable digital signature validation
+ 2 Permit modification of EVM-protected metadata at
+ runtime. Not supported if HMAC validation and
+ creation is enabled.
+ 31 Disable further runtime modification of EVM policy
- Further writes will be blocked if HMAC support is enabled or
- if bit 32 is set:
+ For example:
- echo 0x80000002 ><securityfs>/evm
+ echo 1 ><securityfs>/evm
- will enable digital signature validation and block
- further writes to <securityfs>/evm.
+ will enable HMAC validation and creation
- Until this is done, EVM can not create or validate the
- 'security.evm' xattr, but returns INTEGRITY_UNKNOWN.
- Loading keys and signaling EVM should be done as early
- as possible. Normally this is done in the initramfs,
- which has already been measured as part of the trusted
- boot. For more information on creating and loading
- existing trusted/encrypted keys, refer to:
+ echo 0x80000003 ><securityfs>/evm
- Documentation/security/keys/trusted-encrypted.rst. Both dracut
- (via 97masterkey and 98integrity) and systemd (via
+ will enable HMAC and digital signature validation and
+ HMAC creation and disable all further modification of policy.
+
+ echo 0x80000006 ><securityfs>/evm
+
+ will enable digital signature validation, permit
+ modification of EVM-protected metadata and
+ disable all further modification of policy
+
+ Note that once a key has been loaded, it will no longer be
+ possible to enable metadata modification.
+
+ Until key loading has been signaled EVM can not create
+ or validate the 'security.evm' xattr, but returns
+ INTEGRITY_UNKNOWN. Loading keys and signaling EVM
+ should be done as early as possible. Normally this is
+ done in the initramfs, which has already been measured
+ as part of the trusted boot. For more information on
+ creating and loading existing trusted/encrypted keys,
+ refer to:
+ Documentation/security/keys/trusted-encrypted.rst. Both
+ dracut (via 97masterkey and 98integrity) and systemd (via
core/ima-setup) have support for loading keys at boot
time.
diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy
index e76432b9954d..2028f2d093b2 100644
--- a/Documentation/ABI/testing/ima_policy
+++ b/Documentation/ABI/testing/ima_policy
@@ -17,7 +17,8 @@ Description:
rule format: action [condition ...]
- action: measure | dont_measure | appraise | dont_appraise | audit
+ action: measure | dont_measure | appraise | dont_appraise |
+ audit | hash | dont_hash
condition:= base | lsm [option]
base: [[func=] [mask=] [fsmagic=] [fsuuid=] [uid=]
[euid=] [fowner=]]