ima: handle multiple rules per write

Currently IMA will only accept one rule per write().  This patch allows IMA to
accept writes which contain multiple rules but only processes one rule per
write.  \n is used as the delimiter between rules.  IMA will return a short
write indicating that it only accepted up to the first \n.

This allows simple userspace utilities like cat to be used to load an IMA
policy instead of needing a special userspace utility that understood 'one
write per rule'

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: Mimi Zohar <zohar@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>

1 files changed, 20 insertions, 18 deletions

diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c
index 0c72c9c38956..3674a52e1cfb 100644
--- a/security/integrity/ima/ima_fs.c
+++ b/security/integrity/ima/ima_fs.c
@@ -243,32 +243,34 @@ 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;
-	int rc;
+	char *data = NULL;
+	ssize_t result;
 
 	if (datalen >= PAGE_SIZE)
-		return -ENOMEM;
-	if (*ppos != 0) {
-		/* No partial writes. */
-		return -EINVAL;
-	}
+		datalen = PAGE_SIZE - 1;
+
+	/* No partial writes. */
+	result = -EINVAL;
+	if (*ppos != 0)
+		goto out;
+
+	result = -ENOMEM;
 	data = kmalloc(datalen + 1, GFP_KERNEL);
 	if (!data)
-		return -ENOMEM;
+		goto out;
 
-	if (copy_from_user(data, buf, datalen)) {
-		kfree(data);
-		return -EFAULT;
-	}
 	*(data + datalen) = '\0';
-	rc = ima_parse_add_rule(data);
-	if (rc < 0) {
-		datalen = -EINVAL;
-		valid_policy = 0;
-	}
 
+	result = -EFAULT;
+	if (copy_from_user(data, buf, datalen))
+		goto out;
+
+	result = ima_parse_add_rule(data);
+out:
+	if (result < 0)
+		valid_policy = 0;
 	kfree(data);
-	return datalen;
+	return result;
 }
 
 static struct dentry *ima_dir;