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.

Thanks to Guenter Roeck for his suggestion to substitute memcpy() for
strlcpy().

CC: linux@roeck-us.net
CC: viro@zeniv.linux.org.uk
CC: linux-fsdevel@vger.kernel.org
Signed-off-by: Paul Moore <pmoore@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 20 insertions, 14 deletions

diff --git a/fs/namei.c b/fs/namei.c
index 73fcf4280d6e..71dc1cc23b1a 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -212,32 +212,38 @@ 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);
+        }
+        memcpy((char *)result->name, filename, len);
         result->uptr = NULL;
         result->aname = NULL;
-        result->separate = false;
 
-        strlcpy(kname, filename, EMBEDDED_NAME_MAX);
         return result;
 }