| From bf660111a3dde2847217c9fd82102a8d38193f3e Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Thu, 9 Jul 2020 01:19:01 -0500 |
| Subject: ima: Free the entire rule when deleting a list of rules |
| |
| 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); |
| } |
| } |
| |
| -- |
| 2.25.1 |
| |