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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 <pmoody@google.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
This commit is contained in:
Peter Moody 2012-06-14 10:04:36 -07:00 committed by Mimi Zohar
parent 45e2472e67
commit e7c568e0fd
6 changed files with 56 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
Documentation/ABI/testing/ima_policy
View File

@ -17,7 +17,7 @@ Description:
rule format: action [condition ...]
action: measure | dont_measure | appraise | dont_appraise
action: measure | dont_measure | appraise | dont_appraise | audit
condition:= base | lsm
base: [[func=] [mask=] [fsmagic=] [uid=] [fowner]]
lsm: [[subj_user=] [subj_role=] [subj_type=]

2
security/integrity/ima/ima.h
View File

@ -114,6 +114,8 @@ int ima_collect_measurement(struct integrity_iint_cache *iint,
struct file *file);
void ima_store_measurement(struct integrity_iint_cache *iint, struct file *file,
const unsigned char *filename);
void ima_audit_measurement(struct integrity_iint_cache *iint,
const unsigned char *filename);
int ima_store_template(struct ima_template_entry *entry, int violation,
struct inode *inode);
void ima_template_show(struct seq_file *m, void *e, enum ima_show_type show);

32
security/integrity/ima/ima_api.c
View File

@ -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;
}

9
security/integrity/ima/ima_main.c
View File

@ -156,8 +156,8 @@ static int process_measurement(struct file *file, const unsigned char *filename,
if (!ima_initialized || !S_ISREG(inode->i_mode))
return 0;
/* Determine if in appraise/measurement policy,
* returns IMA_MEASURE, IMA_APPRAISE bitmask. */
/* Determine if in appraise/audit/measurement policy,
* returns IMA_MEASURE, IMA_APPRAISE, IMA_AUDIT bitmask. */
action = ima_get_action(inode, mask, function);
if (!action)
return 0;
@ -171,7 +171,8 @@ static int process_measurement(struct file *file, const unsigned char *filename,
goto out;
/* Determine if already appraised/measured based on bitmask
* (IMA_MEASURE, IMA_MEASURED, IMA_APPRAISE, IMA_APPRAISED) */
* (IMA_MEASURE, IMA_MEASURED, IMA_APPRAISE, IMA_APPRAISED,
* IMA_AUDIT, IMA_AUDITED) */
iint->flags |= action;
action &= ~((iint->flags & IMA_DONE_MASK) >> 1);
@ -202,6 +203,8 @@ static int process_measurement(struct file *file, const unsigned char *filename,
if (action & IMA_APPRAISE)
rc = ima_appraise_measurement(iint, file,
!pathname ? filename : pathname);
if (action & IMA_AUDIT)
ima_audit_measurement(iint, !pathname ? filename : pathname);
kfree(pathbuf);
out:
mutex_unlock(&inode->i_mutex);

11
security/integrity/ima/ima_policy.c
View File

@ -31,6 +31,7 @@
#define DONT_MEASURE 0x0002
#define APPRAISE 0x0004 /* same as IMA_APPRAISE */
#define DONT_APPRAISE 0x0008
#define AUDIT 0x0040
#define MAX_LSM_RULES 6
enum lsm_rule_types { LSM_OBJ_USER, LSM_OBJ_ROLE, LSM_OBJ_TYPE,
@ -277,6 +278,7 @@ enum {
Opt_err = -1,
Opt_measure = 1, Opt_dont_measure,
Opt_appraise, Opt_dont_appraise,
Opt_audit,
Opt_obj_user, Opt_obj_role, Opt_obj_type,
Opt_subj_user, Opt_subj_role, Opt_subj_type,
Opt_func, Opt_mask, Opt_fsmagic, Opt_uid, Opt_fowner
@ -287,6 +289,7 @@ static match_table_t policy_tokens = {
{Opt_dont_measure, "dont_measure"},
{Opt_appraise, "appraise"},
{Opt_dont_appraise, "dont_appraise"},
{Opt_audit, "audit"},
{Opt_obj_user, "obj_user=%s"},
{Opt_obj_role, "obj_role=%s"},
{Opt_obj_type, "obj_type=%s"},
@ -379,6 +382,14 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
entry->action = DONT_APPRAISE;
break;
case Opt_audit:
ima_log_string(ab, "action", "audit");
if (entry->action != UNKNOWN)
result = -EINVAL;
entry->action = AUDIT;
break;
case Opt_func:
ima_log_string(ab, "func", args[0].from);

7
security/integrity/integrity.h
View File

@ -22,12 +22,15 @@
#define IMA_APPRAISED 0x0008
/*#define IMA_COLLECT 0x0010 do not use this flag */
#define IMA_COLLECTED 0x0020
#define IMA_AUDIT 0x0040
#define IMA_AUDITED 0x0080
/* iint cache flags */
#define IMA_DIGSIG 0x0100
#define IMA_DO_MASK (IMA_MEASURE | IMA_APPRAISE)
#define IMA_DONE_MASK (IMA_MEASURED | IMA_APPRAISED | IMA_COLLECTED)
#define IMA_DO_MASK (IMA_MEASURE | IMA_APPRAISE | IMA_AUDIT)
#define IMA_DONE_MASK (IMA_MEASURED | IMA_APPRAISED | IMA_AUDITED \
| IMA_COLLECTED)
enum evm_ima_xattr_type {
IMA_XATTR_DIGEST = 0x01,