ima: provide ">" and "<" operators for fowner/uid/euid rules.
For now we have only "=" operator for fowner/uid/euid rules. This
patch provide two more operators - ">" and "<" in order to make
fowner/uid/euid rules more flexible.
Examples of usage.
Appraise all files owned by special and system users (SYS_UID_MAX 999):
appraise fowner<1000
Don't appraise files owned by normal users (UID_MIN 1000):
dont_appraise fowner>999
Appraise all files owned by users with UID 1000-1010:
dont_appraise fowner>1010
appraise fowner>999
Changelog v3:
- Removed code duplication in ima_parse_rule().
- Fix ima_policy_show() - (Mimi)
Changelog v2:
- Fixed default policy rules.
Signed-off-by: Mikhail Kurinnoi <viewizard@viewizard.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
security/integrity/ima/ima_policy.c | 115 +++++++++++++++++++++++++++---------
1 file changed, 87 insertions(+), 28 deletions(-)
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index e8498a3..3ab1067 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -64,6 +64,8 @@ struct ima_rule_entry {
u8 fsuuid[16];
kuid_t uid;
kuid_t fowner;
+ bool (*uid_op)(kuid_t, kuid_t); /* Handlers for operators */
+ bool (*fowner_op)(kuid_t, kuid_t); /* uid_eq(), uid_gt(), uid_lt() */
int pcr;
struct {
void *rule; /* LSM file metadata specific */
@@ -103,7 +105,8 @@ static struct ima_rule_entry original_measurement_rules[] __ro_after_init = {
{.action = MEASURE, .func = BPRM_CHECK, .mask = MAY_EXEC,
.flags = IMA_FUNC | IMA_MASK},
{.action = MEASURE, .func = FILE_CHECK, .mask = MAY_READ,
- .uid = GLOBAL_ROOT_UID, .flags = IMA_FUNC | IMA_MASK | IMA_UID},
+ .uid = GLOBAL_ROOT_UID, .uid_op = &uid_eq,
+ .flags = IMA_FUNC | IMA_MASK | IMA_UID},
{.action = MEASURE, .func = MODULE_CHECK, .flags = IMA_FUNC},
{.action = MEASURE, .func = FIRMWARE_CHECK, .flags = IMA_FUNC},
};
@@ -114,9 +117,11 @@ static struct ima_rule_entry default_measurement_rules[] __ro_after_init = {
{.action = MEASURE, .func = BPRM_CHECK, .mask = MAY_EXEC,
.flags = IMA_FUNC | IMA_MASK},
{.action = MEASURE, .func = FILE_CHECK, .mask = MAY_READ,
- .uid = GLOBAL_ROOT_UID, .flags = IMA_FUNC | IMA_INMASK | IMA_EUID},
+ .uid = GLOBAL_ROOT_UID, .uid_op = &uid_eq,
+ .flags = IMA_FUNC | IMA_INMASK | IMA_EUID},
{.action = MEASURE, .func = FILE_CHECK, .mask = MAY_READ,
- .uid = GLOBAL_ROOT_UID, .flags = IMA_FUNC | IMA_INMASK | IMA_UID},
+ .uid = GLOBAL_ROOT_UID, .uid_op = &uid_eq,
+ .flags = IMA_FUNC | IMA_INMASK | IMA_UID},
{.action = MEASURE, .func = MODULE_CHECK, .flags = IMA_FUNC},
{.action = MEASURE, .func = FIRMWARE_CHECK, .flags = IMA_FUNC},
{.action = MEASURE, .func = POLICY_CHECK, .flags = IMA_FUNC},
@@ -139,10 +144,11 @@ static struct ima_rule_entry default_appraise_rules[] __ro_after_init = {
.flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
#endif
#ifndef CONFIG_IMA_APPRAISE_SIGNED_INIT
- {.action = APPRAISE, .fowner = GLOBAL_ROOT_UID, .flags = IMA_FOWNER},
+ {.action = APPRAISE, .fowner = GLOBAL_ROOT_UID, .fowner_op = &uid_eq,
+ .flags = IMA_FOWNER},
#else
/* force signature */
- {.action = APPRAISE, .fowner = GLOBAL_ROOT_UID,
+ {.action = APPRAISE, .fowner = GLOBAL_ROOT_UID, .fowner_op = &uid_eq,
.flags = IMA_FOWNER | IMA_DIGSIG_REQUIRED},
#endif
};
@@ -240,19 +246,20 @@ static bool ima_match_rules(struct ima_rule_entry *rule, struct inode *inode,
if ((rule->flags & IMA_FSUUID) &&
memcmp(rule->fsuuid, inode->i_sb->s_uuid, sizeof(rule->fsuuid)))
return false;
- if ((rule->flags & IMA_UID) && !uid_eq(rule->uid, cred->uid))
+ if ((rule->flags & IMA_UID) && !rule->uid_op(cred->uid, rule->uid))
return false;
if (rule->flags & IMA_EUID) {
if (has_capability_noaudit(current, CAP_SETUID)) {
- if (!uid_eq(rule->uid, cred->euid)
- && !uid_eq(rule->uid, cred->suid)
- && !uid_eq(rule->uid, cred->uid))
+ if (!rule->uid_op(cred->euid, rule->uid)
+ && !rule->uid_op(cred->suid, rule->uid)
+ && !rule->uid_op(cred->uid, rule->uid))
return false;
- } else if (!uid_eq(rule->uid, cred->euid))
+ } else if (!rule->uid_op(cred->euid, rule->uid))
return false;
}
- if ((rule->flags & IMA_FOWNER) && !uid_eq(rule->fowner, inode->i_uid))
+ if ((rule->flags & IMA_FOWNER) &&
+ !rule->fowner_op(inode->i_uid, rule->fowner))
return false;
for (i = 0; i < MAX_LSM_RULES; i++) {
int rc = 0;
@@ -486,7 +493,9 @@ enum {
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_fsuuid, Opt_uid, Opt_euid, Opt_fowner,
+ Opt_fsuuid, Opt_uid_eq, Opt_euid_eq, Opt_fowner_eq,
+ Opt_uid_gt, Opt_euid_gt, Opt_fowner_gt,
+ Opt_uid_lt, Opt_euid_lt, Opt_fowner_lt,
Opt_appraise_type, Opt_permit_directio,
Opt_pcr
};
@@ -507,9 +516,15 @@ static match_table_t policy_tokens = {
{Opt_mask, "mask=%s"},
{Opt_fsmagic, "fsmagic=%s"},
{Opt_fsuuid, "fsuuid=%s"},
- {Opt_uid, "uid=%s"},
- {Opt_euid, "euid=%s"},
- {Opt_fowner, "fowner=%s"},
+ {Opt_uid_eq, "uid=%s"},
+ {Opt_euid_eq, "euid=%s"},
+ {Opt_fowner_eq, "fowner=%s"},
+ {Opt_uid_gt, "uid>%s"},
+ {Opt_euid_gt, "euid>%s"},
+ {Opt_fowner_gt, "fowner>%s"},
+ {Opt_uid_lt, "uid<%s"},
+ {Opt_euid_lt, "euid<%s"},
+ {Opt_fowner_lt, "fowner<%s"},
{Opt_appraise_type, "appraise_type=%s"},
{Opt_permit_directio, "permit_directio"},
{Opt_pcr, "pcr=%s"},
@@ -541,24 +556,37 @@ static int ima_lsm_rule_init(struct ima_rule_entry *entry,
return result;
}
-static void ima_log_string(struct audit_buffer *ab, char *key, char *value)
+static void ima_log_string_op(struct audit_buffer *ab, char *key, char *value,
+ bool (*rule_operator)(kuid_t, kuid_t))
{
- audit_log_format(ab, "%s=", key);
+ if (rule_operator == &uid_gt)
+ audit_log_format(ab, "%s>", key);
+ else if (rule_operator == &uid_lt)
+ audit_log_format(ab, "%s<", key);
+ else
+ audit_log_format(ab, "%s=", key);
audit_log_untrustedstring(ab, value);
audit_log_format(ab, " ");
}
+static void ima_log_string(struct audit_buffer *ab, char *key, char *value)
+{
+ ima_log_string_op(ab, key, value, NULL);
+}
static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
{
struct audit_buffer *ab;
char *from;
char *p;
+ bool uid_token;
int result = 0;
ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_INTEGRITY_RULE);
entry->uid = INVALID_UID;
entry->fowner = INVALID_UID;
+ entry->uid_op = &uid_eq;
+ entry->fowner_op = &uid_eq;
entry->action = UNKNOWN;
while ((p = strsep(&rule, " \t")) != NULL) {
substring_t args[MAX_OPT_ARGS];
@@ -694,11 +722,21 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
if (!result)
entry->flags |= IMA_FSUUID;
break;
- case Opt_uid:
- ima_log_string(ab, "uid", args[0].from);
- case Opt_euid:
- if (token == Opt_euid)
- ima_log_string(ab, "euid", args[0].from);
+ case Opt_uid_gt:
+ case Opt_euid_gt:
+ entry->uid_op = &uid_gt;
+ case Opt_uid_lt:
+ case Opt_euid_lt:
+ if ((token == Opt_uid_lt) || (token == Opt_euid_lt))
+ entry->uid_op = &uid_lt;
+ case Opt_uid_eq:
+ case Opt_euid_eq:
+ uid_token = (token == Opt_uid_eq) ||
+ (token == Opt_uid_gt) ||
+ (token == Opt_uid_lt);
+
+ ima_log_string_op(ab, uid_token ? "uid" : "euid",
+ args[0].from, entry->uid_op);
if (uid_valid(entry->uid)) {
result = -EINVAL;
@@ -713,12 +751,18 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
(uid_t)lnum != lnum)
result = -EINVAL;
else
- entry->flags |= (token == Opt_uid)
+ entry->flags |= uid_token
? IMA_UID : IMA_EUID;
}
break;
- case Opt_fowner:
- ima_log_string(ab, "fowner", args[0].from);
+ case Opt_fowner_gt:
+ entry->fowner_op = &uid_gt;
+ case Opt_fowner_lt:
+ if (token == Opt_fowner_lt)
+ entry->fowner_op = &uid_lt;
+ case Opt_fowner_eq:
+ ima_log_string_op(ab, "fowner", args[0].from,
+ entry->fowner_op);
if (uid_valid(entry->fowner)) {
result = -EINVAL;
@@ -1049,19 +1093,34 @@ int ima_policy_show(struct seq_file *m, void *v)
if (entry->flags & IMA_UID) {
snprintf(tbuf, sizeof(tbuf), "%d", __kuid_val(entry->uid));
- seq_printf(m, pt(Opt_uid), tbuf);
+ if (entry->uid_op == &uid_gt)
+ seq_printf(m, pt(Opt_uid_gt), tbuf);
+ else if (entry->uid_op == &uid_lt)
+ seq_printf(m, pt(Opt_uid_lt), tbuf);
+ else
+ seq_printf(m, pt(Opt_uid_eq), tbuf);
seq_puts(m, " ");
}
if (entry->flags & IMA_EUID) {
snprintf(tbuf, sizeof(tbuf), "%d", __kuid_val(entry->uid));
- seq_printf(m, pt(Opt_euid), tbuf);
+ if (entry->uid_op == &uid_gt)
+ seq_printf(m, pt(Opt_euid_gt), tbuf);
+ else if (entry->uid_op == &uid_lt)
+ seq_printf(m, pt(Opt_euid_lt), tbuf);
+ else
+ seq_printf(m, pt(Opt_euid_eq), tbuf);
seq_puts(m, " ");
}
if (entry->flags & IMA_FOWNER) {
snprintf(tbuf, sizeof(tbuf), "%d", __kuid_val(entry->fowner));
- seq_printf(m, pt(Opt_fowner), tbuf);
+ if (entry->fowner_op == &uid_gt)
+ seq_printf(m, pt(Opt_fowner_gt), tbuf);
+ else if (entry->fowner_op == &uid_lt)
+ seq_printf(m, pt(Opt_fowner_lt), tbuf);
+ else
+ seq_printf(m, pt(Opt_fowner_eq), tbuf);
seq_puts(m, " ");
}