@@ -261,6 +261,21 @@ static void ima_lsm_free_rule(struct ima_rule_entry *entry)
security_filter_rule_free(entry->lsm[i].rule);
kfree(entry->lsm[i].args_p);
}
+}
+
+static void ima_free_rule(struct ima_rule_entry *entry)
+{
+ if (!entry)
+ return;
+
+ /*
+ * entry->template->fields may be allocated in ima_parse_rule() but that
+ * reference is owned by the corresponding ima_template_desc element in
+ * the defined_templates list and cannot be freed here
+ */
+ kfree(entry->fsname);
+ kfree(entry->keyrings);
+ ima_lsm_free_rule(entry);
kfree(entry);
}
@@ -302,6 +317,7 @@ static struct ima_rule_entry *ima_lsm_copy_rule(struct ima_rule_entry *entry)
out_err:
ima_lsm_free_rule(nentry);
+ kfree(nentry);
return NULL;
}
@@ -315,7 +331,14 @@ static int ima_lsm_update_rule(struct ima_rule_entry *entry)
list_replace_rcu(&entry->list, &nentry->list);
synchronize_rcu();
+ /*
+ * ima_lsm_copy_rule() shallow copied all references, except for the
+ * LSM references, from entry to nentry so we only want to free the LSM
+ * references and the entry itself. All other memory refrences will now
+ * be owned by nentry.
+ */
ima_lsm_free_rule(entry);
+ kfree(entry);
return 0;
}
@@ -1402,15 +1425,11 @@ ssize_t ima_parse_add_rule(char *rule)
void ima_delete_rules(void)
{
struct ima_rule_entry *entry, *tmp;
- int i;
temp_ima_appraise = 0;
list_for_each_entry_safe(entry, tmp, &ima_temp_rules, list) {
- for (i = 0; i < MAX_LSM_RULES; i++)
- kfree(entry->lsm[i].args_p);
-
list_del(&entry->list);
- kfree(entry);
+ ima_free_rule(entry);
}
}
Create a function, ima_free_rule(), to free all memory associated with an ima_rule_entry. Use the new function to fix memory leaks of allocated ima_rule_entry members, such as .fsname and .keyrings, when deleting a list of rules. Make the existing ima_lsm_free_rule() function specific to the LSM audit rule array of an ima_rule_entry and require that callers make an additional call to kfree to free the ima_rule_entry itself. This fixes a memory leak seen when loading by a valid rule that contains an additional piece of allocated memory, such as an fsname, followed by an invalid rule that triggers a policy load failure: # echo -e "dont_measure fsname=securityfs\nbad syntax" > \ /sys/kernel/security/ima/policy -bash: echo: write error: Invalid argument # echo scan > /sys/kernel/debug/kmemleak # cat /sys/kernel/debug/kmemleak unreferenced object 0xffff9bab67ca12c0 (size 16): comm "bash", pid 684, jiffies 4295212803 (age 252.344s) hex dump (first 16 bytes): 73 65 63 75 72 69 74 79 66 73 00 6b 6b 6b 6b a5 securityfs.kkkk. backtrace: [<00000000adc80b1b>] kstrdup+0x2e/0x60 [<00000000d504cb0d>] ima_parse_add_rule+0x7d4/0x1020 [<00000000444825ac>] ima_write_policy+0xab/0x1d0 [<000000002b7f0d6c>] vfs_write+0xde/0x1d0 [<0000000096feedcf>] ksys_write+0x68/0xe0 [<0000000052b544a2>] do_syscall_64+0x56/0xa0 [<000000007ead1ba7>] entry_SYSCALL_64_after_hwframe+0x44/0xa9 Fixes: f1b08bbcbdaf ("ima: define a new policy condition based on the filesystem name") Fixes: 2b60c0ecedf8 ("IMA: Read keyrings= option from the IMA policy") Signed-off-by: Tyler Hicks <tyhicks@linux.microsoft.com> --- * v3 - No change * v2 - Collapsed patch #2 from v1 of this series, into this patch. This patch now introduces ima_free_rule(). - Existing callers of ima_lsm_free_rule() are doing so to free rules after a successful or failed ima_lsm_copy_rule() and those callers continue to directly call ima_lsm_copy_rule() rather than doing explicit reference ownership and calling ima_free_rule(). - The kfree(entry) of ima_lsm_free_rule() was removed from that function to make it focused on freeing the LSM references. Direct callers of ima_lsm_free_rule() must now call kfree(entry) after ima_lsm_free_rule(). - A comment was added in ima_lsm_update_rule() to clarify why ima_free_rule() isn't being used. security/integrity/ima/ima_policy.c | 29 ++++++++++++++++++++++++----- 1 file changed, 24 insertions(+), 5 deletions(-)