vfs: define struct filename and have getname() return it

getname() is intended to copy pathname strings from userspace into a
kernel buffer. The result is just a string in kernel space. It would
however be quite helpful to be able to attach some ancillary info to
the string.

For instance, we could attach some audit-related info to reduce the
amount of audit-related processing needed. When auditing is enabled,
we could also call getname() on the string more than once and not
need to recopy it from userspace.

This patchset converts the getname()/putname() interfaces to return
a struct instead of a string. For now, the struct just tracks the
string in kernel space and the original userland pointer for it.

Later, we'll add other information to the struct as it becomes
convenient.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 7 insertions, 6 deletions

diff --git a/ipc/mqueue.c b/ipc/mqueue.c
index 9553ed006042..6c5d9dcc9030 100644
--- a/ipc/mqueue.c
+++ b/ipc/mqueue.c
@@ -772,7 +772,7 @@ SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, umode_t, mode,
 {
 	struct path path;
 	struct file *filp;
-	char *name;
+	struct filename *name;
 	struct mq_attr attr;
 	int fd, error;
 	struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
@@ -795,7 +795,7 @@ SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, umode_t, mode,
 	ro = mnt_want_write(mnt);	/* we'll drop it in any case */
 	error = 0;
 	mutex_lock(&root->d_inode->i_mutex);
-	path.dentry = lookup_one_len(name, root, strlen(name));
+	path.dentry = lookup_one_len(name->name, root, strlen(name->name));
 	if (IS_ERR(path.dentry)) {
 		error = PTR_ERR(path.dentry);
 		goto out_putfd;
@@ -804,7 +804,7 @@ SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, umode_t, mode,
 
 	if (oflag & O_CREAT) {
 		if (path.dentry->d_inode) {	/* entry already exists */
-			audit_inode(name, path.dentry, 0);
+			audit_inode(name->name, path.dentry, 0);
 			if (oflag & O_EXCL) {
 				error = -EEXIST;
 				goto out;
@@ -824,7 +824,7 @@ SYSCALL_DEFINE4(mq_open, const char __user *, u_name, int, oflag, umode_t, mode,
 			error = -ENOENT;
 			goto out;
 		}
-		audit_inode(name, path.dentry, 0);
+		audit_inode(name->name, path.dentry, 0);
 		filp = do_open(&path, oflag);
 	}
 
@@ -849,7 +849,7 @@ out_putname:
 SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
 {
 	int err;
-	char *name;
+	struct filename *name;
 	struct dentry *dentry;
 	struct inode *inode = NULL;
 	struct ipc_namespace *ipc_ns = current->nsproxy->ipc_ns;
@@ -863,7 +863,8 @@ SYSCALL_DEFINE1(mq_unlink, const char __user *, u_name)
 	if (err)
 		goto out_name;
 	mutex_lock_nested(&mnt->mnt_root->d_inode->i_mutex, I_MUTEX_PARENT);
-	dentry = lookup_one_len(name, mnt->mnt_root, strlen(name));
+	dentry = lookup_one_len(name->name, mnt->mnt_root,
+				strlen(name->name));
 	if (IS_ERR(dentry)) {
 		err = PTR_ERR(dentry);
 		goto out_unlock;