From 2fe5d6def1672ae6635dd71867bf36dcfaa7434b Mon Sep 17 00:00:00 2001 From: Mimi Zohar Date: Mon, 13 Feb 2012 10:15:05 -0500 Subject: ima: integrity appraisal extension IMA currently maintains an integrity measurement list used to assert the integrity of the running system to a third party. The IMA-appraisal extension adds local integrity validation and enforcement of the measurement against a "good" value stored as an extended attribute 'security.ima'. The initial methods for validating 'security.ima' are hashed based, which provides file data integrity, and digital signature based, which in addition to providing file data integrity, provides authenticity. This patch creates and maintains the 'security.ima' xattr, containing the file data hash measurement. Protection of the xattr is provided by EVM, if enabled and configured. Based on policy, IMA calls evm_verifyxattr() to verify a file's metadata integrity and, assuming success, compares the file's current hash value with the one stored as an extended attribute in 'security.ima'. Changelov v4: - changed iint cache flags to hex values Changelog v3: - change appraisal default for filesystems without xattr support to fail Changelog v2: - fix audit msg 'res' value - removed unused 'ima_appraise=' values Changelog v1: - removed unused iint mutex (Dmitry Kasatkin) - setattr hook must not reset appraised (Dmitry Kasatkin) - evm_verifyxattr() now differentiates between no 'security.evm' xattr (INTEGRITY_NOLABEL) and no EVM 'protected' xattrs included in the 'security.evm' (INTEGRITY_NOXATTRS). - replace hash_status with ima_status (Dmitry Kasatkin) - re-initialize slab element ima_status on free (Dmitry Kasatkin) - include 'security.ima' in EVM if CONFIG_IMA_APPRAISE, not CONFIG_IMA - merged half "ima: ima_must_appraise_or_measure API change" (Dmitry Kasatkin) - removed unnecessary error variable in process_measurement() (Dmitry Kasatkin) - use ima_inode_post_setattr() stub function, if IMA_APPRAISE not configured (moved ima_inode_post_setattr() to ima_appraise.c) - make sure ima_collect_measurement() can read file Changelog: - add 'iint' to evm_verifyxattr() call (Dimitry Kasatkin) - fix the race condition between chmod, which takes the i_mutex and then iint->mutex, and ima_file_free() and process_measurement(), which take the locks in the reverse order, by eliminating iint->mutex. (Dmitry Kasatkin) - cleanup of ima_appraise_measurement() (Dmitry Kasatkin) - changes as a result of the iint not allocated for all regular files, but only for those measured/appraised. - don't try to appraise new/empty files - expanded ima_appraisal description in ima/Kconfig - IMA appraise definitions required even if IMA_APPRAISE not enabled - add return value to ima_must_appraise() stub - unconditionally set status = INTEGRITY_PASS *after* testing status, not before. (Found by Joe Perches) Signed-off-by: Mimi Zohar Signed-off-by: Dmitry Kasatkin --- security/integrity/ima/ima_api.c | 50 +++++++++++++++++++++++++++++----------- 1 file changed, 36 insertions(+), 14 deletions(-) (limited to 'security/integrity/ima/ima_api.c') diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c index 032ff03ad907..41cce84416c5 100644 --- a/security/integrity/ima/ima_api.c +++ b/security/integrity/ima/ima_api.c @@ -9,13 +9,17 @@ * License. * * File: ima_api.c - * Implements must_measure, collect_measurement, store_measurement, - * and store_template. + * Implements must_appraise_or_measure, collect_measurement, + * appraise_measurement, store_measurement and store_template. */ #include #include - +#include +#include +#include +#include #include "ima.h" + static const char *IMA_TEMPLATE_NAME = "ima"; /* @@ -93,7 +97,7 @@ err_out: } /** - * ima_must_measure - measure decision based on policy. + * ima_must_appraise_or_measure - appraise & measure decision based on policy. * @inode: pointer to inode to measure * @mask: contains the permission mask (MAY_READ, MAY_WRITE, MAY_EXECUTE) * @function: calling function (FILE_CHECK, BPRM_CHECK, FILE_MMAP) @@ -105,15 +109,22 @@ err_out: * mask: contains the permission mask * fsmagic: hex value * - * Return 0 to measure. For matching a DONT_MEASURE policy, no policy, - * or other error, return an error code. -*/ -int ima_must_measure(struct inode *inode, int mask, int function) + * Returns IMA_MEASURE, IMA_APPRAISE mask. + * + */ +int ima_must_appraise_or_measure(struct inode *inode, int mask, int function) { - int must_measure; + int flags = IMA_MEASURE | IMA_APPRAISE; + + if (!ima_appraise) + flags &= ~IMA_APPRAISE; + + return ima_match_policy(inode, function, mask, flags); +} - must_measure = ima_match_policy(inode, function, mask); - return must_measure ? 0 : -EACCES; +int ima_must_measure(struct inode *inode, int mask, int function) +{ + return ima_match_policy(inode, function, mask, IMA_MEASURE); } /* @@ -129,16 +140,24 @@ int ima_must_measure(struct inode *inode, int mask, int function) int ima_collect_measurement(struct integrity_iint_cache *iint, struct file *file) { - int result = -EEXIST; + struct inode *inode = file->f_dentry->d_inode; + const char *filename = file->f_dentry->d_name.name; + int result = 0; - if (!(iint->flags & IMA_MEASURED)) { + if (!(iint->flags & IMA_COLLECTED)) { u64 i_version = file->f_dentry->d_inode->i_version; memset(iint->digest, 0, IMA_DIGEST_SIZE); result = ima_calc_hash(file, iint->digest); - if (!result) + if (!result) { iint->version = i_version; + iint->flags |= IMA_COLLECTED; + } } + if (result) + integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode, + filename, "collect_data", "failed", + result, 0); return result; } @@ -167,6 +186,9 @@ void ima_store_measurement(struct integrity_iint_cache *iint, struct ima_template_entry *entry; int violation = 0; + if (iint->flags & IMA_MEASURED) + return; + entry = kmalloc(sizeof(*entry), GFP_KERNEL); if (!entry) { integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode, filename, -- cgit v1.2.3 From 5a44b41207174e1882ce0c24a752f4cfb65dab07 Mon Sep 17 00:00:00 2001 From: Mimi Zohar Date: Mon, 9 Jan 2012 22:59:36 -0500 Subject: ima: add support for different security.ima data types IMA-appraisal currently verifies the integrity of a file based on a known 'good' measurement value. This patch reserves the first byte of 'security.ima' as a place holder for the type of method used for verifying file data integrity. Changelog v1: - Use the newly defined 'struct evm_ima_xattr_data' Signed-off-by: Dmitry Kasatkin Signed-off-by: Mimi Zohar --- security/integrity/ima/ima_api.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'security/integrity/ima/ima_api.c') diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c index 41cce84416c5..33d46859753a 100644 --- a/security/integrity/ima/ima_api.c +++ b/security/integrity/ima/ima_api.c @@ -147,8 +147,8 @@ int ima_collect_measurement(struct integrity_iint_cache *iint, if (!(iint->flags & IMA_COLLECTED)) { u64 i_version = file->f_dentry->d_inode->i_version; - memset(iint->digest, 0, IMA_DIGEST_SIZE); - result = ima_calc_hash(file, iint->digest); + iint->ima_xattr.type = IMA_XATTR_DIGEST; + result = ima_calc_hash(file, iint->ima_xattr.digest); if (!result) { iint->version = i_version; iint->flags |= IMA_COLLECTED; @@ -196,7 +196,7 @@ void ima_store_measurement(struct integrity_iint_cache *iint, return; } memset(&entry->template, 0, sizeof(entry->template)); - memcpy(entry->template.digest, iint->digest, IMA_DIGEST_SIZE); + memcpy(entry->template.digest, iint->ima_xattr.digest, IMA_DIGEST_SIZE); strcpy(entry->template.file_name, (strlen(filename) > IMA_EVENT_NAME_LEN_MAX) ? file->f_dentry->d_name.name : filename); -- cgit v1.2.3 From d9d300cdb6f233c4c591348919c758062198a4f4 Mon Sep 17 00:00:00 2001 From: Dmitry Kasatkin Date: Wed, 27 Jun 2012 11:26:14 +0300 Subject: ima: rename ima_must_appraise_or_measure When AUDIT action support is added to the IMA, ima_must_appraise_or_measure() does not reflect the real meaning anymore. Rename it to ima_get_action(). Signed-off-by: Dmitry Kasatkin Signed-off-by: Mimi Zohar --- security/integrity/ima/ima_api.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'security/integrity/ima/ima_api.c') diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c index 33d46859753a..f0d60e754b3e 100644 --- a/security/integrity/ima/ima_api.c +++ b/security/integrity/ima/ima_api.c @@ -97,7 +97,7 @@ err_out: } /** - * ima_must_appraise_or_measure - appraise & measure decision based on policy. + * ima_get_action - appraise & measure decision based on policy. * @inode: pointer to inode to measure * @mask: contains the permission mask (MAY_READ, MAY_WRITE, MAY_EXECUTE) * @function: calling function (FILE_CHECK, BPRM_CHECK, FILE_MMAP) @@ -112,7 +112,7 @@ err_out: * Returns IMA_MEASURE, IMA_APPRAISE mask. * */ -int ima_must_appraise_or_measure(struct inode *inode, int mask, int function) +int ima_get_action(struct inode *inode, int mask, int function) { int flags = IMA_MEASURE | IMA_APPRAISE; -- cgit v1.2.3 From e7c568e0fd0cf6d9c8ab8ea537ba8f3a3ae7c3d8 Mon Sep 17 00:00:00 2001 From: Peter Moody Date: Thu, 14 Jun 2012 10:04:36 -0700 Subject: ima: audit log hashes This adds an 'audit' policy action which audit logs file measurements. Changelog v6: - use new action flag handling (Dmitry Kasatkin). - removed whitespace (Mimi) Changelog v5: - use audit_log_untrustedstring. Changelog v4: - cleanup digest -> hash conversion. - use filename rather than d_path in ima_audit_measurement. Changelog v3: - Use newly exported audit_log_task_info for logging pid/ppid/uid/etc. - Update the ima_policy ABI documentation. Changelog v2: - Use 'audit' action rather than 'measure_and_audit' to permit auditing in the absence of measuring.. Changelog v1: - Initial posting. Signed-off-by: Peter Moody Signed-off-by: Mimi Zohar --- security/integrity/ima/ima_api.c | 32 +++++++++++++++++++++++++++++++- 1 file changed, 31 insertions(+), 1 deletion(-) (limited to 'security/integrity/ima/ima_api.c') diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c index f0d60e754b3e..b356884fb3ef 100644 --- a/security/integrity/ima/ima_api.c +++ b/security/integrity/ima/ima_api.c @@ -114,7 +114,7 @@ err_out: */ int ima_get_action(struct inode *inode, int mask, int function) { - int flags = IMA_MEASURE | IMA_APPRAISE; + int flags = IMA_MEASURE | IMA_AUDIT | IMA_APPRAISE; if (!ima_appraise) flags &= ~IMA_APPRAISE; @@ -207,3 +207,33 @@ void ima_store_measurement(struct integrity_iint_cache *iint, if (result < 0) kfree(entry); } + +void ima_audit_measurement(struct integrity_iint_cache *iint, + const unsigned char *filename) +{ + struct audit_buffer *ab; + char hash[(IMA_DIGEST_SIZE * 2) + 1]; + int i; + + if (iint->flags & IMA_AUDITED) + return; + + for (i = 0; i < IMA_DIGEST_SIZE; i++) + hex_byte_pack(hash + (i * 2), iint->ima_xattr.digest[i]); + hash[i * 2] = '\0'; + + ab = audit_log_start(current->audit_context, GFP_KERNEL, + AUDIT_INTEGRITY_RULE); + if (!ab) + return; + + audit_log_format(ab, "file="); + audit_log_untrustedstring(ab, filename); + audit_log_format(ab, " hash="); + audit_log_untrustedstring(ab, hash); + + audit_log_task_info(ab, current); + audit_log_end(ab); + + iint->flags |= IMA_AUDITED; +} -- cgit v1.2.3