linux-kernel - [RFC PATCH 1/5] fs: rework getname_kernel to handle up to PATH

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Date:	Thu, 08 Jan 2015 11:50:30 -0500
From:	Paul Moore <pmoore@...hat.com>
To:	linux-audit@...hat.com, viro@...iv.linux.org.uk
Cc:	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [RFC PATCH 1/5] fs: rework getname_kernel to handle up to PATH_MAX
 sized filenames

In preparation for expanded use in the kernel, make getname_kernel()
more useful by allowing it to handle any legal filename length.

Signed-off-by: Paul Moore <pmoore@...hat.com>
---
 fs/namei.c |   34 ++++++++++++++++++++--------------
 1 file changed, 20 insertions(+), 14 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index 9eb787e..eeb3b83 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -211,32 +211,38 @@ getname(const char __user * filename)
 	return getname_flags(filename, 0, NULL);
 }
 
-/*
- * The "getname_kernel()" interface doesn't do pathnames longer
- * than EMBEDDED_NAME_MAX. Deal with it - you're a kernel user.
- */
 struct filename *
 getname_kernel(const char * filename)
 {
 	struct filename *result;
-	char *kname;
-	int len;
-
-	len = strlen(filename);
-	if (len >= EMBEDDED_NAME_MAX)
-		return ERR_PTR(-ENAMETOOLONG);
+	int len = strlen(filename) + 1;
 
 	result = __getname();
 	if (unlikely(!result))
 		return ERR_PTR(-ENOMEM);
 
-	kname = (char *)result + sizeof(*result);
-	result->name = kname;
+	if (len <= EMBEDDED_NAME_MAX) {
+		result->name = (char *)(result) + sizeof(*result);
+		result->separate = false;
+	} else if (len <= PATH_MAX) {
+		struct filename *tmp;
+
+		tmp = kmalloc(sizeof(*tmp), GFP_KERNEL);
+		if (unlikely(!tmp)) {
+			__putname(result);
+			return ERR_PTR(-ENOMEM);
+		}
+		tmp->name = (char *)result;
+		tmp->separate = true;
+		result = tmp;
+	} else {
+		__putname(result);
+		return ERR_PTR(-ENAMETOOLONG);
+	}
+	strlcpy((char *)result->name, filename, len);
 	result->uptr = NULL;
 	result->aname = NULL;
-	result->separate = false;
 
-	strlcpy(kname, filename, EMBEDDED_NAME_MAX);
 	return result;
 }
 

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