From: Tyler Hicks <tyhicks@linux.microsoft.com>
To: Mimi Zohar <zohar@linux.ibm.com>,
Dmitry Kasatkin <dmitry.kasatkin@gmail.com>
Cc: James Morris <jmorris@namei.org>,
"Serge E . Hallyn" <serge@hallyn.com>,
Lakshmi Ramasubramanian <nramas@linux.microsoft.com>,
Prakhar Srivastava <prsriva02@gmail.com>,
linux-kernel@vger.kernel.org, linux-integrity@vger.kernel.org,
linux-security-module@vger.kernel.org
Subject: [PATCH v3 02/12] ima: Free the entire rule when deleting a list of rules
Date: Thu, 9 Jul 2020 01:19:01 -0500 [thread overview]
Message-ID: <20200709061911.954326-3-tyhicks@linux.microsoft.com> (raw)
In-Reply-To: <20200709061911.954326-1-tyhicks@linux.microsoft.com>
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(-)
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);
}
}
--
2.25.1
next prev parent reply other threads:[~2020-07-09 6:20 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-09 6:18 [PATCH v3 00/12] ima: Fix rule parsing bugs and extend KEXEC_CMDLINE rule support Tyler Hicks
2020-07-09 6:19 ` [PATCH v3 01/12] ima: Have the LSM free its audit rule Tyler Hicks
2020-07-17 19:20 ` Nayna
2020-07-17 19:24 ` Tyler Hicks
2020-07-19 11:02 ` Mimi Zohar
2020-07-09 6:19 ` Tyler Hicks [this message]
2020-07-09 6:19 ` [PATCH v3 03/12] ima: Free the entire rule if it fails to parse Tyler Hicks
2020-07-09 6:19 ` [PATCH v3 04/12] ima: Fail rule parsing when buffer hook functions have an invalid action Tyler Hicks
2020-07-09 6:19 ` [PATCH v3 05/12] ima: Fail rule parsing when the KEXEC_CMDLINE hook is combined with an invalid cond Tyler Hicks
2020-07-09 6:19 ` [PATCH v3 06/12] ima: Fail rule parsing when the KEY_CHECK " Tyler Hicks
2020-07-17 18:56 ` Nayna
2020-07-17 19:18 ` Tyler Hicks
2020-07-17 23:39 ` Tyler Hicks
2020-07-09 6:19 ` [PATCH v3 07/12] ima: Fail rule parsing when appraise_flag=blacklist is unsupportable Tyler Hicks
2020-07-16 18:14 ` Mimi Zohar
2020-07-16 18:20 ` Tyler Hicks
[not found] ` <76d2b27b-3b59-1852-046a-b1718c62b167@linux.vnet.ibm.com>
2020-07-17 18:11 ` Tyler Hicks
2020-07-20 17:02 ` Nayna
2020-07-09 6:19 ` [PATCH v3 08/12] ima: Shallow copy the args_p member of ima_rule_entry.lsm elements Tyler Hicks
2020-07-17 15:35 ` Konsta Karsisto
2020-07-17 16:51 ` Tyler Hicks
2020-07-09 6:19 ` [PATCH v3 09/12] ima: Use correct type for " Tyler Hicks
2020-07-09 6:19 ` [PATCH v3 10/12] ima: Move comprehensive rule validation checks out of the token parser Tyler Hicks
2020-07-09 6:19 ` [PATCH v3 11/12] ima: Use the common function to detect LSM conditionals in a rule Tyler Hicks
2020-07-09 6:19 ` [PATCH v3 12/12] ima: Support additional conditionals in the KEXEC_CMDLINE hook function Tyler Hicks
2020-07-17 4:31 ` [PATCH v3 00/12] ima: Fix rule parsing bugs and extend KEXEC_CMDLINE rule support Mimi Zohar
2020-07-17 4:34 ` Tyler Hicks
2020-07-20 21:38 ` Mimi Zohar
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