linux-kernel - [PATCH -next] user_namespace: Replace gotos with return statements

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Date:   Wed, 18 Apr 2018 23:46:38 -0300
From:   Marcos Paulo de Souza <marcos.souza.org@...il.com>
To:     linux-next@...r.kernel.org
Cc:     Marcos Paulo de Souza <marcos.souza.org@...il.com>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Christian Brauner <christian.brauner@...ntu.com>,
        Mark Rutland <mark.rutland@....com>,
        Ingo Molnar <mingo@...nel.org>,
        Serge Hallyn <serge@...lyn.com>,
        Seth Forshee <seth.forshee@...onical.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH -next] user_namespace: Replace gotos with return statements

Found while inspecting the code that handles the setgroups procfs file.

Signed-off-by: Marcos Paulo de Souza <marcos.souza.org@...il.com>
---
Tested locally setting up a new userns, and setting setgroups as deny and allow,
worked as before.

 kernel/user_namespace.c | 20 +++++++-------------
 1 file changed, 7 insertions(+), 13 deletions(-)

diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index 246d4d4ce5c7..64a01254ac6b 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -1142,22 +1142,18 @@ ssize_t proc_setgroups_write(struct file *file, const char __user *buf,
 	struct user_namespace *ns = seq->private;
 	char kbuf[8], *pos;
 	bool setgroups_allowed;
-	ssize_t ret;
 
 	/* Only allow a very narrow range of strings to be written */
-	ret = -EINVAL;
 	if ((*ppos != 0) || (count >= sizeof(kbuf)))
-		goto out;
+		return -EINVAL;
 
 	/* What was written? */
-	ret = -EFAULT;
 	if (copy_from_user(kbuf, buf, count))
-		goto out;
+		return -EFAULT;
 	kbuf[count] = '\0';
 	pos = kbuf;
 
 	/* What is being requested? */
-	ret = -EINVAL;
 	if (strncmp(pos, "allow", 5) == 0) {
 		pos += 5;
 		setgroups_allowed = true;
@@ -1167,14 +1163,13 @@ ssize_t proc_setgroups_write(struct file *file, const char __user *buf,
 		setgroups_allowed = false;
 	}
 	else
-		goto out;
+		return -EINVAL;
 
 	/* Verify there is not trailing junk on the line */
 	pos = skip_spaces(pos);
 	if (*pos != '\0')
-		goto out;
+		return -EINVAL;
 
-	ret = -EPERM;
 	mutex_lock(&userns_state_mutex);
 	if (setgroups_allowed) {
 		/* Enabling setgroups after setgroups has been disabled
@@ -1194,12 +1189,11 @@ ssize_t proc_setgroups_write(struct file *file, const char __user *buf,
 
 	/* Report a successful write */
 	*ppos = count;
-	ret = count;
-out:
-	return ret;
+	return count;
+
 out_unlock:
 	mutex_unlock(&userns_state_mutex);
-	goto out;
+	return -EPERM;
 }
 
 bool userns_may_setgroups(const struct user_namespace *ns)
-- 
2.14.3