[PATCH v2 1/5] fs: rework getname_kernel to handle up to PATH_MAX sized filenames

Paul Moore
2015-01-22T05:00:14Z

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>
---
fs/namei.c | 34 ++++++++++++++++++++--------------
1 file changed, 20 insertions(+), 14 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index 9eb787e..63eaaf6 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);
+ }
+ memcpy((char *)result->name, filename, len);
result->uptr = NULL;
result->aname = NULL;
- result->separate = false;

- strlcpy(kname, filename, EMBEDDED_NAME_MAX);
return result;
}