ima: added ima_policy_flag variable

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 <roberto.sassu@polito.it>
Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index d61680dcd365..8ee997dff139 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -43,6 +43,9 @@ enum tpm_pcrs { TPM_PCR0 = 0, TPM_PCR8 = 8 };
 #define IMA_TEMPLATE_IMA_NAME "ima"
 #define IMA_TEMPLATE_IMA_FMT "d|n"
 
+/* current content of the policy */
+extern int ima_policy_flag;
+
 /* set during initialization */
 extern int ima_initialized;
 extern int ima_used_chip;
@@ -153,6 +156,7 @@ int ima_match_policy(struct inode *inode, enum ima_hooks func, int mask,
 		     int flags);
 void ima_init_policy(void);
 void ima_update_policy(void);
+void ima_update_policy_flag(void);
 ssize_t ima_parse_add_rule(char *);
 void ima_delete_rules(void);