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 <pet...@mip-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 <pet...@mip-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
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