kernel/security/integrity/ima/ima_main.c, branch linux-4.1.y

ima: fix hash algorithm initialization

2018-01-17T17:55:17Z

[ Upstream commit ebe7c0a7be92bbd34c6ff5b55810546a0ee05bee ] The hash_setup function always sets the hash_setup_done flag, even when the hash algorithm is invalid. This prevents the default hash algorithm defined as CONFIG_IMA_DEFAULT_HASH from being used. This patch sets hash_setup_done flag only for valid hash algorithms. Fixes: e7a2ad7eb6f4 "ima: enable support for larger default filedata hash algorithms" Signed-off-by: Boshi Wang Signed-off-by: Mimi Zohar Signed-off-by: Sasha Levin

ima: use path names cache

2014-10-07T18:32:54Z

__getname() uses slab allocation which is faster than kmalloc. Make use of it. Signed-off-by: Dmitry Kasatkin Signed-off-by: Mimi Zohar

ima: check ima_policy_flag in the ima_file_free() hook

2014-10-07T18:32:52Z

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 Acked-by: Roberto Sassu

ima: detect violations for mmaped files

2014-09-18T14:04:12Z

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

ima: fix race condition on ima_rdwr_violation_check and process_measurement

2014-09-18T14:03:55Z

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

ima: added ima_policy_flag variable

2014-09-17T20:39:36Z

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: move keyring initialization to ima_init()

2014-09-17T20:10:59Z

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 Signed-off-by: Mimi Zohar

ima: remove usage of filename parameter

2014-09-09T14:28:52Z

In all cases except ima_bprm_check() the filename was not defined and ima_d_path() was used to find the full path. Unfortunately, the bprm filename is a relative pathname (eg. .//filename). ima_bprm_check() selects between bprm->interp and bprm->filename. The following dump demonstrates the differences between using filename and interp. bprm->filename filename: ./foo.sh, pathname: /root/bin/foo.sh filename: ./foo.sh, pathname: /bin/dash bprm->interp filename: ./foo.sh, pathname: /root/bin/foo.sh filename: /bin/sh, pathname: /bin/dash In both cases the pathnames are currently the same. This patch removes usage of filename and interp in favor of d_absolute_path. Changes v3: - 11 extra bytes for "deleted" not needed (Mimi) - purpose "replace relative bprm filename with full pathname" (Mimi) Changes v2: - use d_absolute_path() instead of d_path to work in chroot environments. Signed-off-by: Dmitry Kasatkin Signed-off-by: Mimi Zohar

ima: remove unnecessary extra variable

2014-09-09T14:28:48Z

'function' variable value can be changed instead of allocating extra '_func' variable. Signed-off-by: Dmitry Kasatkin Signed-off-by: Mimi Zohar

ima: simplify conditional statement to improve performance

2014-09-09T14:28:47Z

Precede bit testing before string comparison makes code faster. Also refactor statement as a single line pointer assignment. Logic is following: we set 'xattr_ptr' to read xattr value when we will do appraisal or in any case when measurement template is other than 'ima'. Signed-off-by: Dmitry Kasatkin Signed-off-by: Mimi Zohar