From 1b68bdf9cded82d37e443a20c5ed47bbb084d5dc Mon Sep 17 00:00:00 2001 From: Roberto Sassu Date: Fri, 12 Sep 2014 19:35:56 +0200 Subject: [PATCH] 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 Signed-off-by: Dmitry Kasatkin Signed-off-by: Mimi Zohar --- security/integrity/ima/ima_api.c | 5 ----- security/integrity/ima/ima_main.c | 9 +++++---- 2 files changed, 5 insertions(+), 9 deletions(-) diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c index 65c41a9..8688597 100644 --- a/security/integrity/ima/ima_api.c +++ b/security/integrity/ima/ima_api.c @@ -179,11 +179,6 @@ int ima_get_action(struct inode *inode, int mask, int function) return ima_match_policy(inode, function, mask, flags); } -int ima_must_measure(struct inode *inode, int mask, int function) -{ - return ima_match_policy(inode, function, mask, IMA_MEASURE); -} - /* * ima_collect_measurement - collect file measurement * diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c index 03bb52ec..62f59ec 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -79,6 +79,7 @@ __setup("ima_hash=", hash_setup); */ static void ima_rdwr_violation_check(struct file *file, struct integrity_iint_cache *iint, + int must_measure, char **pathbuf, const char **pathname) { @@ -95,8 +96,7 @@ static void ima_rdwr_violation_check(struct file *file, send_tomtou = true; } } else { - if ((atomic_read(&inode->i_writecount) > 0) && - ima_must_measure(inode, MAY_READ, FILE_CHECK)) + if ((atomic_read(&inode->i_writecount) > 0) && must_measure) send_writers = true; } @@ -174,7 +174,7 @@ static int process_measurement(struct file *file, int mask, int function, * Included is the appraise submask. */ action = ima_get_action(inode, mask, function); - violation_check = (function == FILE_CHECK && + violation_check = ((function == FILE_CHECK || function == MMAP_CHECK) && (ima_policy_flag & IMA_MEASURE)); if (!action && !violation_check) return 0; @@ -194,7 +194,8 @@ static int process_measurement(struct file *file, int mask, int function, } if (violation_check) { - ima_rdwr_violation_check(file, iint, &pathbuf, &pathname); + ima_rdwr_violation_check(file, iint, action & IMA_MEASURE, + &pathbuf, &pathname); if (!action) { rc = 0; goto out_free; -- 2.7.4