wireguard-linux/Documentation/ABI/testing/ima_policy, branch jd/unified-crypt-queue

IMA: Add support to limit measuring keys

2019-12-12T13:53:50Z

Limit measuring keys to those keys being loaded onto a given set of keyrings only and when the user id (uid) matches if uid is specified in the policy. This patch defines a new IMA policy option namely "keyrings=" that can be used to specify a set of keyrings. If this option is specified in the policy for "measure func=KEY_CHECK" then only the keys loaded onto a keyring given in the "keyrings=" option are measured. If uid is specified in the policy then the key is measured only if the current user id matches the one specified in the policy. Added a new parameter namely "keyring" (name of the keyring) to process_buffer_measurement(). The keyring name is passed to ima_get_action() to determine the required action. ima_match_rules() is updated to check keyring in the policy, if specified, for KEY_CHECK function. Signed-off-by: Lakshmi Ramasubramanian Signed-off-by: Mimi Zohar

IMA: Add KEY_CHECK func to measure keys

2019-12-12T13:53:50Z

Measure keys loaded onto any keyring. This patch defines a new IMA policy func namely KEY_CHECK to measure keys. Updated ima_match_rules() to check for KEY_CHECK and ima_parse_rule() to handle KEY_CHECK. Signed-off-by: Lakshmi Ramasubramanian Signed-off-by: Mimi Zohar

ima: Check against blacklisted hashes for files with modsig

2019-11-12T01:25:50Z

Asymmetric private keys are used to sign multiple files. The kernel currently supports checking against blacklisted keys. However, if the public key is blacklisted, any file signed by the blacklisted key will automatically fail signature verification. Blacklisting the public key is not fine enough granularity, as we might want to only blacklist a particular file. This patch adds support for checking against the blacklisted hash of the file, without the appended signature, based on the IMA policy. It defines a new policy option "appraise_flag=check_blacklist". In addition to the blacklisted binary hashes stored in the firmware "dbx" variable, the Linux kernel may be configured to load blacklisted binary hashes onto the .blacklist keyring as well. The following example shows how to blacklist a specific kernel module hash. $ sha256sum kernel/kheaders.ko 77fa889b35a05338ec52e51591c1b89d4c8d1c99a21251d7c22b1a8642a6bad3 kernel/kheaders.ko $ grep BLACKLIST .config CONFIG_SYSTEM_BLACKLIST_KEYRING=y CONFIG_SYSTEM_BLACKLIST_HASH_LIST="blacklist-hash-list" $ cat certs/blacklist-hash-list "bin:77fa889b35a05338ec52e51591c1b89d4c8d1c99a21251d7c22b1a8642a6bad3" Update the IMA custom measurement and appraisal policy rules (/etc/ima-policy): measure func=MODULE_CHECK template=ima-modsig appraise func=MODULE_CHECK appraise_flag=check_blacklist appraise_type=imasig|modsig After building, installing, and rebooting the kernel: 545660333 ---lswrv 0 0 \_ blacklist: bin:77fa889b35a05338ec52e51591c1b89d4c8d1c99a21251d7c22b1a8642a6bad3 measure func=MODULE_CHECK template=ima-modsig appraise func=MODULE_CHECK appraise_flag=check_blacklist appraise_type=imasig|modsig modprobe: ERROR: could not insert 'kheaders': Permission denied 10 0c9834db5a0182c1fb0cdc5d3adcf11a11fd83dd ima-sig sha256:3bc6ed4f0b4d6e31bc1dbc9ef844605abc7afdc6d81a57d77a1ec9407997c40 2 /usr/lib/modules/5.4.0-rc3+/kernel/kernel/kheaders.ko 10 82aad2bcc3fa8ed94762356b5c14838f3bcfa6a0 ima-modsig sha256:3bc6ed4f0b4d6e31bc1dbc9ef844605abc7afdc6d81a57d77a1ec9407997c40 2 /usr/lib/modules/5.4.0rc3+/kernel/kernel/kheaders.ko sha256:77fa889b3 5a05338ec52e51591c1b89d4c8d1c99a21251d7c22b1a8642a6bad3 3082029a06092a864886f70d010702a082028b30820287020101310d300b0609608648 016503040201300b06092a864886f70d01070131820264.... 10 25b72217cc1152b44b134ce2cd68f12dfb71acb3 ima-buf sha256:8b58427fedcf8f4b20bc8dc007f2e232bf7285d7b93a66476321f9c2a3aa132 b blacklisted-hash 77fa889b35a05338ec52e51591c1b89d4c8d1c99a21251d7c22b1a8642a6bad3 Signed-off-by: Nayna Jain [zohar@linux.ibm.com: updated patch description] Signed-off-by: Mimi Zohar Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/1572492694-6520-8-git-send-email-zohar@linux.ibm.com

ima: Add modsig appraise_type option for module-style appended signatures

2019-08-05T22:40:21Z

Introduce the modsig keyword to the IMA policy syntax to specify that a given hook should expect the file to have the IMA signature appended to it. Here is how it can be used in a rule: appraise func=KEXEC_KERNEL_CHECK appraise_type=imasig|modsig With this rule, IMA will accept either a signature stored in the extended attribute or an appended signature. For now, the rule above will behave exactly the same as if appraise_type=imasig was specified. The actual modsig implementation will be introduced separately. Suggested-by: Mimi Zohar Signed-off-by: Thiago Jung Bauermann Signed-off-by: Mimi Zohar

IMA: Define a new hook to measure the kexec boot command line arguments

2019-06-24T12:29:57Z

Currently during soft reboot(kexec_file_load) boot command line arguments are not measured. Define hooks needed to measure kexec command line arguments during soft reboot(kexec_file_load). - A new ima hook ima_kexec_cmdline is defined to be called by the kexec code. - A new function process_buffer_measurement is defined to measure the buffer hash into the IMA measurement list. - A new func policy KEXEC_CMDLINE is defined to control the measurement. Signed-off-by: Prakhar Srivastava Signed-off-by: Mimi Zohar

IMA: support for per policy rule template formats

2019-06-19T22:51:01Z

Admins may wish to log different measurements using different IMA templates. Add support for overriding the default template on a per-rule basis. Inspired-by: Roberto Sassu Signed-off-by: Matthew Garrett Signed-off-by: Mimi Zohar

ima: define a new policy condition based on the filesystem name

2018-05-22T11:33:53Z

If/when file data signatures are distributed with the file data, this patch will not be needed. In the current environment where only some files are signed, the ability to differentiate between file systems is needed. Some file systems consider the file system magic number internal to the file system. This patch defines a new IMA policy condition named "fsname", based on the superblock's file_system_type (sb->s_type) name. This allows policy rules to be expressed in terms of the filesystem name. The following sample rules require file signatures on rootfs files executed or mmap'ed. appraise func=BPRM_CHECK fsname=rootfs appraise_type=imasig appraise func=FILE_MMAP fsname=rootfs appraise_type=imasig Signed-off-by: Mimi Zohar Cc: Dave Chinner Cc: Theodore Ts'o

IMA: Support using new creds in appraisal policy

2018-03-23T10:31:11Z

The existing BPRM_CHECK functionality in IMA validates against the credentials of the existing process, not any new credentials that the child process may transition to. Add an additional CREDS_CHECK target and refactor IMA to pass the appropriate creds structure. In ima_bprm_check(), check with both the existing process credentials and the credentials that will be committed when the new process is started. This will not change behaviour unless the system policy is extended to include CREDS_CHECK targets - BPRM_CHECK will continue to check the same credentials that it did previously. After this patch, an IMA policy rule along the lines of: measure func=CREDS_CHECK subj_type=unconfined_t will trigger if a process is executed and runs as unconfined_t, ignoring the context of the parent process. This is in contrast to: measure func=BPRM_CHECK subj_type=unconfined_t which will trigger if the process that calls exec() is already executing in unconfined_t, ignoring the context that the child process executes into. Signed-off-by: Matthew Garrett Signed-off-by: Mimi Zohar Changelog: - initialize ima_creds_status

ima: support new "hash" and "dont_hash" policy actions

2017-12-18T14:43:38Z

The builtin ima_appraise_tcb policy, which is specified on the boot command line, can be replaced with a custom policy, normally early in the boot process. Custom policies can be more restrictive in some ways, like requiring file signatures, but can be less restrictive in other ways, like not appraising mutable files. With a less restrictive policy in place, files in the builtin policy might not be hashed and labeled with a security.ima hash. On reboot, files which should be labeled in the ima_appraise_tcb are not labeled, possibly preventing the system from booting properly. To resolve this problem, this patch extends the existing IMA policy actions "measure", "dont_measure", "appraise", "dont_appraise", and "audit" with "hash" and "dont_hash". The new "hash" action will write the file hash as security.ima, but without requiring the file to be appraised as well. For example, the builtin ima_appraise_tcb policy includes the rule, "appraise fowner=0". Adding the "hash fowner=0" rule to a custom policy, will cause the needed file hashes to be calculated and written as security.ima xattrs. Signed-off-by: Mimi Zohar Signed-off-by: Stefan Berger

IMA: update IMA policy documentation to include pcr= option

2017-06-21T18:37:12Z

Commit 0260643ce "ima: add policy support for extending different pcrs" introduced a new IMA policy option "pcr=". Missing was the documentation for this option. This patch updates ima_policy to include this option, as well as an example. Signed-off-by: Eric Richter Signed-off-by: Mimi Zohar