From: Tyler Hicks tyhicks@linux.microsoft.com
[ Upstream commit 465aee77aae857b5fcde56ee192b33dc369fba04 ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- security/integrity/ima/ima_policy.c | 29 ++++++++++++++++++++++++----- 1 file changed, 24 insertions(+), 5 deletions(-)
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c index 236a731492d1e..641582230861c 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); } }