[PATCH 0/3] Backporting some memory leak of ima policy to 4.19+ from mainline

[PATCH 0/3] Backporting some memory leak of ima policy to 4.19+ from mainline

[gouhao]

From: Gou Hao <gouhao@uniontech.com>

patch1: is memory leak of audit rule
patch2~3: is memory leak about 'fsname' field of struct ima_rule_entry

Tyler Hicks (3):
  ima: Have the LSM free its audit rule
  ima: Free the entire rule when deleting a list of rules
  ima: Free the entire rule if it fails to parse

 security/integrity/ima/ima.h        |  5 +++++
 security/integrity/ima/ima_policy.c | 24 ++++++++++++++++++------
 2 files changed, 23 insertions(+), 6 deletions(-)

-- 
2.20.1

[PATCH 1/3] ima: Have the LSM free its audit rule

[gouhao]

From: Tyler Hicks <tyhicks@linux.microsoft.com>

commit 9ff8a616dfab96a4fa0ddd36190907dc68886d9b upstream.

Ask the LSM to free its audit rule rather than directly calling kfree().
Both AppArmor and SELinux do additional work in their audit_rule_free()
hooks. Fix memory leaks by allowing the LSMs to perform necessary work.

Fixes: b16942455193 ("ima: use the lsm policy update notifier")
Signed-off-by: Tyler Hicks <tyhicks@linux.microsoft.com>
Cc: Janne Karhunen <janne.karhunen@gmail.com>
Cc: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Cc: <stable@vger.kernel.org> # 4.19+
Signed-off-by: Gou Hao <gouhao@uniontech.com>
---
 security/integrity/ima/ima.h        | 5 +++++
 security/integrity/ima/ima_policy.c | 4 +++-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index d12b07eb3a58..e2916b115b93 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -298,6 +298,7 @@ static inline int ima_read_xattr(struct dentry *dentry,
 #ifdef CONFIG_IMA_LSM_RULES
 
 #define security_filter_rule_init security_audit_rule_init
+#define security_filter_rule_free security_audit_rule_free
 #define security_filter_rule_match security_audit_rule_match
 
 #else
@@ -308,6 +309,10 @@ static inline int security_filter_rule_init(u32 field, u32 op, char *rulestr,
 	return -EINVAL;
 }
 
+static inline void security_filter_rule_free(void *lsmrule)
+{
+}
+
 static inline int security_filter_rule_match(u32 secid, u32 field, u32 op,
 					     void *lsmrule,
 					     struct audit_context *actx)
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index 2d5a3daa02f9..733efc06d3c1 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -1044,8 +1044,10 @@ void ima_delete_rules(void)
 
 	temp_ima_appraise = 0;
 	list_for_each_entry_safe(entry, tmp, &ima_temp_rules, list) {
-		for (i = 0; i < MAX_LSM_RULES; i++)
+		for (i = 0; i < MAX_LSM_RULES; i++) {
+			security_filter_rule_free(entry->lsm[i].rule);
 			kfree(entry->lsm[i].args_p);
+		}
 
 		list_del(&entry->list);
 		kfree(entry);
-- 
2.20.1

[PATCH 2/3] ima: Free the entire rule when deleting a list of rules

[gouhao]

From: Tyler Hicks <tyhicks@linux.microsoft.com>

commit 465aee77aae857b5fcde56ee192b33dc369fba04 upstream.

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>
Cc: <stable@vger.kernel.org> # 4.19+
Signed-off-by: Gou Hao <gouhao@uniontech.com>
---
 security/integrity/ima/ima_policy.c | 23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index 733efc06d3c1..8a55bdfad404 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -241,6 +241,21 @@ static int __init default_appraise_policy_setup(char *str)
 }
 __setup("ima_appraise_tcb", default_appraise_policy_setup);
 
+static void ima_free_rule(struct ima_rule_entry *entry)
+{
+	int i;
+
+	if (!entry)
+		return;
+
+	kfree(entry->fsname);
+	for (i = 0; i < MAX_LSM_RULES; i++) {
+		security_filter_rule_free(entry->lsm[i].rule);
+		kfree(entry->lsm[i].args_p);
+	}
+	kfree(entry);
+}
+
 /*
  * The LSM policy can be reloaded, leaving the IMA LSM based rules referring
  * to the old, stale LSM policy.  Update the IMA LSM based rules to reflect
@@ -1040,17 +1055,11 @@ 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++) {
-			security_filter_rule_free(entry->lsm[i].rule);
-			kfree(entry->lsm[i].args_p);
-		}
-
 		list_del(&entry->list);
-		kfree(entry);
+		ima_free_rule(entry);
 	}
 }
 
-- 
2.20.1

[PATCH 3/3] ima: Free the entire rule if it fails to parse

[gouhao]

From: Tyler Hicks <tyhicks@linux.microsoft.com>

commit 2bdd737c5687d6dec30e205953146ede8a87dbdd upstream.

Use ima_free_rule() to fix memory leaks of allocated ima_rule_entry
members, such as .fsname and .keyrings, when an error is encountered
during rule parsing.

Set the args_p pointer to NULL after freeing it in the error path of
ima_lsm_rule_init() so that it isn't freed twice.

This fixes a memory leak seen when loading an rule that contains an
additional piece of allocated memory, such as an fsname, followed by an
invalid conditional:

 # echo "measure fsname=tmpfs bad=cond" > /sys/kernel/security/ima/policy
 -bash: echo: write error: Invalid argument
 # echo scan > /sys/kernel/debug/kmemleak
 # cat /sys/kernel/debug/kmemleak
 unreferenced object 0xffff98e7e4ece6c0 (size 8):
   comm "bash", pid 672, jiffies 4294791843 (age 21.855s)
   hex dump (first 8 bytes):
     74 6d 70 66 73 00 6b a5                          tmpfs.k.
   backtrace:
     [<00000000abab7413>] kstrdup+0x2e/0x60
     [<00000000f11ede32>] ima_parse_add_rule+0x7d4/0x1020
     [<00000000f883dd7a>] ima_write_policy+0xab/0x1d0
     [<00000000b17cf753>] vfs_write+0xde/0x1d0
     [<00000000b8ddfdea>] ksys_write+0x68/0xe0
     [<00000000b8e21e87>] do_syscall_64+0x56/0xa0
     [<0000000089ea7b98>] 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>
Cc: <stable@vger.kernel.org> # 4.19+
Signed-off-by: Gou Hao <gouhao@uniontech.com>
---
 security/integrity/ima/ima_policy.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index 8a55bdfad404..b2dadff3626b 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -662,6 +662,7 @@ static int ima_lsm_rule_init(struct ima_rule_entry *entry,
 					   &entry->lsm[lsm_rule].rule);
 	if (!entry->lsm[lsm_rule].rule) {
 		kfree(entry->lsm[lsm_rule].args_p);
+		entry->lsm[lsm_rule].args_p = NULL;
 		return -EINVAL;
 	}
 
@@ -1034,7 +1035,7 @@ ssize_t ima_parse_add_rule(char *rule)
 
 	result = ima_parse_rule(p, entry);
 	if (result) {
-		kfree(entry);
+		ima_free_rule(entry);
 		integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
 				    NULL, op, "invalid-policy", result,
 				    audit_info);
-- 
2.20.1

Re: [PATCH 0/3] Backporting some memory leak of ima policy to 4.19+ from mainline

[Greg KH]

On Fri, Sep 30, 2022 at 03:49:34PM +0800, gouhao@uniontech.com wrote:
> From: Gou Hao <gouhao@uniontech.com>
> 
> patch1: is memory leak of audit rule
> patch2~3: is memory leak about 'fsname' field of struct ima_rule_entry
> 
> Tyler Hicks (3):
>   ima: Have the LSM free its audit rule
>   ima: Free the entire rule when deleting a list of rules
>   ima: Free the entire rule if it fails to parse
> 
>  security/integrity/ima/ima.h        |  5 +++++
>  security/integrity/ima/ima_policy.c | 24 ++++++++++++++++++------
>  2 files changed, 23 insertions(+), 6 deletions(-)
> 
> -- 
> 2.20.1
> 

Now queued up, thanks.

greg k-h

Re: [PATCH 0/3] Backporting some memory leak of ima policy to 4.19+ from mainline

[Tyler Hicks]

On 2022-10-02 17:35:24, Greg KH wrote:
> On Fri, Sep 30, 2022 at 03:49:34PM +0800, gouhao@uniontech.com wrote:
> > From: Gou Hao <gouhao@uniontech.com>
> > 
> > patch1: is memory leak of audit rule
> > patch2~3: is memory leak about 'fsname' field of struct ima_rule_entry
> > 
> > Tyler Hicks (3):
> >   ima: Have the LSM free its audit rule
> >   ima: Free the entire rule when deleting a list of rules
> >   ima: Free the entire rule if it fails to parse
> > 
> >  security/integrity/ima/ima.h        |  5 +++++
> >  security/integrity/ima/ima_policy.c | 24 ++++++++++++++++++------
> >  2 files changed, 23 insertions(+), 6 deletions(-)
> > 
> > -- 
> > 2.20.1
> > 
> 
> Now queued up, thanks.

I know these patches have been already applied and were even released a
couple days ago but I wanted to say that I reviewed these backports,
since they were a little tricky, and they all look good. Thanks for
doing this, Gou!

Tyler

> 
> greg k-h
>