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Subject[RFC][PATCH 7/7] ima: added new LSM conditions in the policy
Date
The new parameters 'fowner_user', 'fowner_role' and 'fowner_type' are new
LSM conditions that allow to measure inodes whose opened file descriptor
has the label given as a value.

Signed-off-by: Roberto Sassu <roberto.sassu@polito.it>
---
Documentation/ABI/testing/ima_policy | 7 ++++-
security/integrity/ima/ima.h | 4 +-
security/integrity/ima/ima_api.c | 4 +-
security/integrity/ima/ima_main.c | 4 +-
security/integrity/ima/ima_policy.c | 45 +++++++++++++++++++++++++++++----
5 files changed, 51 insertions(+), 13 deletions(-)
diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy
index 6cd6dae..ee49345 100644
--- a/Documentation/ABI/testing/ima_policy
+++ b/Documentation/ABI/testing/ima_policy
@@ -18,7 +18,8 @@ Description:
condition:= base | lsm
base: [[func=] [mask=] [fsmagic=] [uid=]]
lsm: [[subj_user=] [subj_role=] [subj_type=]
- [obj_user=] [obj_role=] [obj_type=]]
+ [obj_user=] [obj_role=] [obj_type=]
+ [fowner_user=] [fowner_role=] [fowner_type=]]

base: func:= [BPRM_CHECK][FILE_MMAP][FILE_CHECK]
mask:= [MAY_READ] [MAY_WRITE] [MAY_APPEND] [MAY_EXEC]
@@ -46,6 +47,10 @@ Description:
all files mmapped executable in file_mmap, and all files
open for read by root in do_filp_open.

+ LSM conditions starting with obj_ refer to security attributes
+ of inodes while those starting with fowner_ involve file
+ descriptors.
+
Examples of LSM specific definitions:

SELinux:
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index 08408bd..3a05625 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -110,7 +110,7 @@ struct ima_iint_cache {
};

/* LIM API function definitions */
-int ima_must_measure(struct inode *inode, int mask, int function);
+int ima_must_measure(struct file *file, int mask, int function);
int ima_collect_measurement(struct ima_iint_cache *iint, struct file *file);
void ima_store_measurement(struct ima_iint_cache *iint, struct file *file,
const unsigned char *filename);
@@ -128,7 +128,7 @@ struct ima_iint_cache *ima_iint_find(struct inode *inode);
/* IMA policy related functions */
enum ima_hooks { FILE_CHECK = 1, FILE_MMAP, BPRM_CHECK };

-int ima_match_policy(struct inode *inode, enum ima_hooks func, int mask);
+int ima_match_policy(struct file *file, enum ima_hooks func, int mask);
void ima_init_policy(void);
void ima_update_policy(void);
ssize_t ima_parse_add_rule(char *);
diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
index da36d2c..d815392 100644
--- a/security/integrity/ima/ima_api.c
+++ b/security/integrity/ima/ima_api.c
@@ -108,11 +108,11 @@ err_out:
* 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)
+int ima_must_measure(struct file *file, int mask, int function)
{
int must_measure;

- must_measure = ima_match_policy(inode, function, mask);
+ must_measure = ima_match_policy(file, function, mask);
return must_measure ? 0 : -EACCES;
}

diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 39d66dc..9eaca61 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -65,7 +65,7 @@ static void ima_rdwr_violation_check(struct file *file)
goto out;
}

- rc = ima_must_measure(inode, MAY_READ, FILE_CHECK);
+ rc = ima_must_measure(file, MAY_READ, FILE_CHECK);
if (rc < 0)
goto out;

@@ -127,7 +127,7 @@ static int process_measurement(struct file *file, const unsigned char *filename,
if (!ima_initialized || !S_ISREG(inode->i_mode))
return 0;

- rc = ima_must_measure(inode, mask, function);
+ rc = ima_must_measure(file, mask, function);
if (rc != 0)
return rc;
retry:
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index d661afb..115c2e7 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -27,9 +27,10 @@

enum ima_action { UNKNOWN = -1, DONT_MEASURE = 0, MEASURE };

-#define MAX_LSM_RULES 6
+#define MAX_LSM_RULES 9
enum lsm_rule_types { LSM_OBJ_USER, LSM_OBJ_ROLE, LSM_OBJ_TYPE,
- LSM_SUBJ_USER, LSM_SUBJ_ROLE, LSM_SUBJ_TYPE
+ LSM_SUBJ_USER, LSM_SUBJ_ROLE, LSM_SUBJ_TYPE,
+ LSM_FOWNER_USER, LSM_FOWNER_ROLE, LSM_FOWNER_TYPE
};

struct ima_measure_rule_entry {
@@ -96,9 +97,10 @@ __setup("ima_tcb", default_policy_setup);
* Returns true on rule match, false on failure.
*/
static bool ima_match_rules(struct ima_measure_rule_entry *rule,
- struct inode *inode, enum ima_hooks func, int mask)
+ struct file *file, enum ima_hooks func, int mask)
{
struct task_struct *tsk = current;
+ struct inode *inode = file->f_dentry->d_inode;
int i;

if ((rule->flags & IMA_FUNC) && rule->func != func)
@@ -112,7 +114,7 @@ static bool ima_match_rules(struct ima_measure_rule_entry *rule,
return false;
for (i = 0; i < MAX_LSM_RULES; i++) {
int rc = 0;
- u32 osid, sid;
+ u32 osid, sid, fsid;

if (!rule->lsm[i].rule)
continue;
@@ -137,6 +139,15 @@ static bool ima_match_rules(struct ima_measure_rule_entry *rule,
Audit_equal,
rule->lsm[i].rule,
NULL);
+ case LSM_FOWNER_USER:
+ case LSM_FOWNER_ROLE:
+ case LSM_FOWNER_TYPE:
+ security_file_getsecid(file, &fsid);
+ rc = security_filter_rule_match(fsid,
+ rule->lsm[i].type,
+ Audit_equal,
+ rule->lsm[i].rule,
+ NULL);
default:
break;
}
@@ -159,14 +170,14 @@ static bool ima_match_rules(struct ima_measure_rule_entry *rule,
* as elements in the list are never deleted, nor does the list
* change.)
*/
-int ima_match_policy(struct inode *inode, enum ima_hooks func, int mask)
+int ima_match_policy(struct file *file, enum ima_hooks func, int mask)
{
struct ima_measure_rule_entry *entry;

list_for_each_entry(entry, ima_measure, list) {
bool rc;

- rc = ima_match_rules(entry, inode, func, mask);
+ rc = ima_match_rules(entry, file, func, mask);
if (rc)
return entry->action;
}
@@ -222,6 +233,7 @@ enum {
Opt_measure = 1, Opt_dont_measure,
Opt_obj_user, Opt_obj_role, Opt_obj_type,
Opt_subj_user, Opt_subj_role, Opt_subj_type,
+ Opt_fowner_user, Opt_fowner_role, Opt_fowner_type,
Opt_func, Opt_mask, Opt_fsmagic, Opt_uid
};

@@ -234,6 +246,9 @@ static match_table_t policy_tokens = {
{Opt_subj_user, "subj_user=%s"},
{Opt_subj_role, "subj_role=%s"},
{Opt_subj_type, "subj_type=%s"},
+ {Opt_fowner_user, "fowner_user=%s"},
+ {Opt_fowner_role, "fowner_role=%s"},
+ {Opt_fowner_type, "fowner_type=%s"},
{Opt_func, "func=%s"},
{Opt_mask, "mask=%s"},
{Opt_fsmagic, "fsmagic=%s"},
@@ -407,6 +422,24 @@ static int ima_parse_rule(char *rule, struct ima_measure_rule_entry *entry)
LSM_SUBJ_TYPE,
AUDIT_SUBJ_TYPE);
break;
+ case Opt_fowner_user:
+ ima_log_string(ab, "fowner_user", args[0].from);
+ result = ima_lsm_rule_init(entry, args[0].from,
+ LSM_FOWNER_USER,
+ AUDIT_SUBJ_USER);
+ break;
+ case Opt_fowner_role:
+ ima_log_string(ab, "fowner_role", args[0].from);
+ result = ima_lsm_rule_init(entry, args[0].from,
+ LSM_FOWNER_ROLE,
+ AUDIT_SUBJ_ROLE);
+ break;
+ case Opt_fowner_type:
+ ima_log_string(ab, "fowner_type", args[0].from);
+ result = ima_lsm_rule_init(entry, args[0].from,
+ LSM_FOWNER_TYPE,
+ AUDIT_SUBJ_TYPE);
+ break;
case Opt_err:
ima_log_string(ab, "UNKNOWN", p);
result = -EINVAL;
--
1.7.4.4
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