linux-kernel - Re: linux-next: manual merge of the security tree with the vfs tree

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Fri, 1 Jan 2016 19:29:37 +0200
From:	Petko Manolov <petkan@...-labs.com>
To:	Al Viro <viro@...IV.linux.org.uk>
Cc:	Stephen Rothwell <sfr@...b.auug.org.au>,
	James Morris <jmorris@...ei.org>, linux-next@...r.kernel.org,
	linux-kernel@...r.kernel.org, Mimi Zohar <zohar@...ux.vnet.ibm.com>
Subject: Re: linux-next: manual merge of the security tree with the vfs tree

On 16-01-01 04:34:16, Al Viro wrote:
> On Thu, Dec 31, 2015 at 12:45:35PM +0200, Petko Manolov wrote:
> 
> > I introduced the write mutex when ima_write_policy() stopped being serialized by 
> > other means.  Come to think about it the semaphore could be taken right before 
> > copy_from_user() so it is my fault, not Stephen's.
> 
> s/before/after/, surely?

Right.  This is a quick patch which i hope solves most issues...


		Petko


>From 6c9058009c59fda5b8e98a3fc09497ce3efdb3e9 Mon Sep 17 00:00:00 2001
From: Petko Manolov <petkan@...-labs.com>
Date: Fri, 1 Jan 2016 19:10:43 +0200
Subject: [PATCH] ima_write_policy() optimizations;

There is no need to hold the write semaphore for so long.  We only need it
around ima_parse_add_rule();

The return path now takes into account failed kmalloc() call.

Signed-off-by: Petko Manolov <petkan@...-labs.com>
---
 security/integrity/ima/ima_fs.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c
index 3caed6d..d2c0d55 100644
--- a/security/integrity/ima/ima_fs.c
+++ b/security/integrity/ima/ima_fs.c
@@ -261,13 +261,7 @@ static const struct file_operations ima_ascii_measurements_ops = {
 static ssize_t ima_write_policy(struct file *file, const char __user *buf,
 				size_t datalen, loff_t *ppos)
 {
-	char *data = NULL;
 	ssize_t result;
-	int res;
-
-	res = mutex_lock_interruptible(&ima_write_mutex);
-	if (res)
-		return res;
 
 	if (datalen >= PAGE_SIZE)
 		datalen = PAGE_SIZE - 1;
@@ -286,15 +280,21 @@ static ssize_t ima_write_policy(struct file *file, const char __user *buf,
 
 	result = -EFAULT;
 	if (copy_from_user(data, buf, datalen))
-		goto out;
+		goto out_free;
+
+	result = mutex_lock_interruptible(&ima_write_mutex);
+	if (result)
+		goto out_free;
 
 	result = ima_parse_add_rule(data);
-out:
+
+	mutex_unlock(&ima_write_mutex);
+
 	if (result < 0)
 		valid_policy = 0;
+out_free:
 	kfree(data);
-	mutex_unlock(&ima_write_mutex);
-
+out:
 	return result;
 }
 
-- 
2.6.4


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/