[RFC PATCH 2/5] fs: create proper filename objects using getname_kernel()

[Paul Moore]

There are several areas in the kernel that create temporary filename
objects using the following pattern:

	int func(const char *name)
	{
		struct filename *file = { .name = name };
		...
		return 0;
	}

... which for the most part works okay, but it causes havoc within the
audit subsystem as the filename object does not persist beyond the
lifetime of the function.  This patch converts all of these temporary
filename objects into proper filename objects using getname_kernel()
and putname() which ensure that the filename object persists until the
audit subsystem is finished with it.

Signed-off-by: Paul Moore <pmoore@xxxxxxxxxx>
---
 fs/exec.c  |   11 +++++++++--
 fs/namei.c |   34 ++++++++++++++++++++++++++--------
 fs/open.c  |   11 +++++++++--
 3 files changed, 44 insertions(+), 12 deletions(-)

diff --git a/fs/exec.c b/fs/exec.c
index a3d33fe..d067771 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -789,8 +789,15 @@ exit:
 
 struct file *open_exec(const char *name)
 {
-	struct filename tmp = { .name = name };
-	return do_open_exec(&tmp);
+	struct file *file;
+	struct filename *tmp;
+
+	tmp = getname_kernel(name);
+	if (unlikely(IS_ERR(tmp)))
+		return (void *)tmp;
+	file = do_open_exec(tmp);
+	putname(tmp);
+	return file;
 }
 EXPORT_SYMBOL(open_exec);
 
diff --git a/fs/namei.c b/fs/namei.c
index eeb3b83..c3d21b7 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -2001,9 +2001,15 @@ static int filename_lookup(int dfd, struct filename *name,
 static int do_path_lookup(int dfd, const char *name,
 				unsigned int flags, struct nameidata *nd)
 {
-	struct filename filename = { .name = name };
+	int retval;
+	struct filename *filename;
 
-	return filename_lookup(dfd, &filename, flags, nd);
+	filename = getname_kernel(name);
+	if (unlikely(IS_ERR(filename)))
+		return PTR_ERR(filename);
+	retval = filename_lookup(dfd, filename, flags, nd);
+	putname(filename);
+	return retval;
 }
 
 /* does lookup, returns the object with parent locked */
@@ -2368,8 +2374,15 @@ int
 kern_path_mountpoint(int dfd, const char *name, struct path *path,
 			unsigned int flags)
 {
-	struct filename s = {.name = name};
-	return filename_mountpoint(dfd, &s, path, flags);
+	int retval;
+	struct filename *s;
+
+	s = getname_kernel(name);
+	if (unlikely(IS_ERR(s)))
+		return PTR_ERR(s);
+	retval = filename_mountpoint(dfd, s, path, flags);
+	putname(s);
+	return retval;
 }
 EXPORT_SYMBOL(kern_path_mountpoint);
 
@@ -3259,7 +3272,7 @@ struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt,
 {
 	struct nameidata nd;
 	struct file *file;
-	struct filename filename = { .name = name };
+	struct filename *filename;
 	int flags = op->lookup_flags | LOOKUP_ROOT;
 
 	nd.root.mnt = mnt;
@@ -3268,11 +3281,16 @@ struct file *do_file_open_root(struct dentry *dentry, struct vfsmount *mnt,
 	if (d_is_symlink(dentry) && op->intent & LOOKUP_OPEN)
 		return ERR_PTR(-ELOOP);
 
-	file = path_openat(-1, &filename, &nd, op, flags | LOOKUP_RCU);
+	filename = getname_kernel(name);
+	if (unlikely(IS_ERR(filename)))
+		return (void *)filename;
+
+	file = path_openat(-1, filename, &nd, op, flags | LOOKUP_RCU);
 	if (unlikely(file == ERR_PTR(-ECHILD)))
-		file = path_openat(-1, &filename, &nd, op, flags);
+		file = path_openat(-1, filename, &nd, op, flags);
 	if (unlikely(file == ERR_PTR(-ESTALE)))
-		file = path_openat(-1, &filename, &nd, op, flags | LOOKUP_REVAL);
+		file = path_openat(-1, filename, &nd, op, flags | LOOKUP_REVAL);
+	putname(filename);
 	return file;
 }
 
diff --git a/fs/open.c b/fs/open.c
index d6fd3ac..666982b 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -940,8 +940,15 @@ struct file *file_open_name(struct filename *name, int flags, umode_t mode)
  */
 struct file *filp_open(const char *filename, int flags, umode_t mode)
 {
-	struct filename name = {.name = filename};
-	return file_open_name(&name, flags, mode);
+	struct file *file;
+	struct filename *name;
+
+	name = getname_kernel(filename);
+	if (unlikely(IS_ERR(name)))
+		return (void *)name;
+	file = file_open_name(name, flags, mode);
+	putname(name);
+	return file;
 }
 EXPORT_SYMBOL(filp_open);
 

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