diff options
author | Tyler Hicks <tyhicks@linux.microsoft.com> | 2020-07-09 01:19:01 -0500 |
---|---|---|
committer | Mimi Zohar <zohar@linux.ibm.com> | 2020-07-16 21:53:55 -0400 |
commit | 465aee77aae857b5fcde56ee192b33dc369fba04 (patch) | |
tree | 93af011214a09602a4ab788c4f0e6a3508a4c1b9 /security/integrity | |
parent | 9ff8a616dfab96a4fa0ddd36190907dc68886d9b (diff) |
ima: Free the entire rule when deleting a list of rules
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>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Diffstat (limited to 'security/integrity')
-rw-r--r-- | security/integrity/ima/ima_policy.c | 29 |
1 files changed, 24 insertions, 5 deletions
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c index d7c268c2b0ce..bf00b966e87f 100644 --- a/security/integrity/ima/ima_policy.c +++ b/security/integrity/ima/ima_policy.c @@ -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); } } |