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From: Mimi Zohar on 30 Jul 2010 11:50
The default appraisal policy measures all files owned by root.
This patch extends the policy language with 'owner'.

Signed-off-by: Mimi Zohar <zohar(a)us.ibm.com>
---
Documentation/ABI/testing/ima_policy | 22 ++++++++++++++++++----
security/integrity/ima/ima_policy.c | 23 +++++++++++++++++++++--
2 files changed, 39 insertions(+), 6 deletions(-)

diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy
index 6cd6dae..c0ddeef 100644
--- a/Documentation/ABI/testing/ima_policy
+++ b/Documentation/ABI/testing/ima_policy
@@ -12,11 +12,14 @@ Description:
then closing the file. The new policy takes effect after
the file ima/policy is closed.

+ IMA appraisal, if configured, uses these file measurements
+ for local measurement appraisal.
+
rule format: action [condition ...]

- action: measure | dont_measure
+ action: measure | dont_measure | appraise | dont_appraise
condition:= base | lsm
- base: [[func=] [mask=] [fsmagic=] [uid=]]
+ base: [[func=] [mask=] [fsmagic=] [uid=] [owner]]
lsm: [[subj_user=] [subj_role=] [subj_type=]
[obj_user=] [obj_role=] [obj_type=]]

@@ -24,36 +27,47 @@ Description:
mask:= [MAY_READ] [MAY_WRITE] [MAY_APPEND] [MAY_EXEC]
fsmagic:= hex value
uid:= decimal value
+ owner:=decimal value
lsm: are LSM specific

default policy:
# PROC_SUPER_MAGIC
dont_measure fsmagic=0x9fa0
+ dont_appraise fsmagic=0x9fa0
# SYSFS_MAGIC
dont_measure fsmagic=0x62656572
+ dont_appraise fsmagic=0x62656572
# DEBUGFS_MAGIC
dont_measure fsmagic=0x64626720
+ dont_appraise fsmagic=0x64626720
# TMPFS_MAGIC
dont_measure fsmagic=0x01021994
+ dont_appraise fsmagic=0x01021994
# SECURITYFS_MAGIC
dont_measure fsmagic=0x73636673
+ dont_appraise fsmagic=0x73636673

measure func=BPRM_CHECK
measure func=FILE_MMAP mask=MAY_EXEC
measure func=FILE_CHECK mask=MAY_READ uid=0
+ appraise owner=0

The default policy measures all executables in bprm_check,
all files mmapped executable in file_mmap, and all files
- open for read by root in do_filp_open.
+ open for read by root in do_filp_open. The default appraisal
+ policy appraises all files owned by root.

Examples of LSM specific definitions:

SELinux:
# SELINUX_MAGIC
- dont_measure fsmagic=0xF97CFF8C
+ dont_measure fsmagic=0xf97cff8c
+ dont_appraise fsmagic=0xf97cff8c

dont_measure obj_type=var_log_t
+ dont_appraise obj_type=var_log_t
dont_measure obj_type=auditd_log_t
+ dont_appraise obj_type=auditd_log_t
measure subj_user=system_u func=FILE_CHECK mask=MAY_READ
measure subj_role=system_r func=FILE_CHECK mask=MAY_READ

diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index 96d5b45..4a7faa8 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -261,7 +261,7 @@ enum {
Opt_appraise, Opt_dont_appraise,
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_func, Opt_mask, Opt_fsmagic, Opt_uid, Opt_owner
};

static match_table_t policy_tokens = {
@@ -279,6 +279,7 @@ static match_table_t policy_tokens = {
{Opt_mask, "mask=%s"},
{Opt_fsmagic, "fsmagic=%s"},
{Opt_uid, "uid=%s"},
+ {Opt_owner, "owner=%s"},
{Opt_err, NULL}
};

@@ -313,6 +314,7 @@ static int ima_parse_rule(char *rule, struct ima_measure_rule_entry *entry)
ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_INTEGRITY_RULE);

entry->uid = -1;
+ entry->owner = -1;
entry->action = UNKNOWN;
while ((p = strsep(&rule, " \t")) != NULL) {
substring_t args[MAX_OPT_ARGS];
@@ -361,7 +363,7 @@ static int ima_parse_rule(char *rule, struct ima_measure_rule_entry *entry)
ima_log_string(ab, "func", args[0].from);

if (entry->func)
- result = -EINVAL;
+ result = -EINVAL;

if (strcmp(args[0].from, "FILE_CHECK") == 0)
entry->func = FILE_CHECK;
@@ -426,6 +428,23 @@ static int ima_parse_rule(char *rule, struct ima_measure_rule_entry *entry)
entry->flags |= IMA_UID;
}
break;
+ case Opt_owner:
+ ima_log_string(ab, "owner", args[0].from);
+
+ if (entry->owner != -1) {
+ result = -EINVAL;
+ break;
+ }
+
+ result = strict_strtoul(args[0].from, 10, &lnum);
+ if (!result) {
+ entry->owner = (uid_t) lnum;
+ if (entry->owner != lnum)
+ result = -EINVAL;
+ else
+ entry->flags |= IMA_OWNER;
+ }
+ break;
case Opt_obj_user:
ima_log_string(ab, "obj_user", args[0].from);
result = ima_lsm_rule_init(entry, args[0].from,
--
1.7.1.1

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Prev: [PATCH v3 09/15] fs: add evm_inode_post_init calls
Next: [PATCH v3 13/15] ima: add ima_inode_setxattr and ima_inode_removexattr