[PATCH 1/2] fs: make do_mkdirat() take struct filename

Dmitry Kadashev
2020-11-11T13:26:07Z

Pass in the struct filename pointers instead of the user string, and
update the three callers to do the same. This is heavily based on
commit dbea8d345177 ("fs: make do_renameat2() take struct filename").

This behaves like do_unlinkat() and do_renameat2().

Signed-off-by: Dmitry Kadashev <dkadashev@gmail.com>
---
fs/internal.h | 1 +
fs/namei.c | 20 ++++++++++++++------
2 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/fs/internal.h b/fs/internal.h
index 6fd14ea213c3..23b8b427dbd2 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -80,6 +80,7 @@ long do_unlinkat(int dfd, struct filename *name);
int may_linkat(struct path *link);
int do_renameat2(int olddfd, struct filename *oldname, int newdfd,
struct filename *newname, unsigned int flags);
+long do_mkdirat(int dfd, struct filename *name, umode_t mode);

/*
* namespace.c
diff --git a/fs/namei.c b/fs/namei.c
index 03d0e11e4f36..9d26a51f3f54 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -3654,17 +3654,23 @@ int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
}
EXPORT_SYMBOL(vfs_mkdir);

-static long do_mkdirat(int dfd, const char __user *pathname, umode_t mode)
+long do_mkdirat(int dfd, struct filename *name, umode_t mode)
{
struct dentry *dentry;
struct path path;
int error;
unsigned int lookup_flags = LOOKUP_DIRECTORY;

+ if (IS_ERR(name))
+ return PTR_ERR(name);
+
retry:
- dentry = user_path_create(dfd, pathname, &path, lookup_flags);
- if (IS_ERR(dentry))
- return PTR_ERR(dentry);
+ name->refcnt++; /* filename_create() drops our ref */
+ dentry = filename_create(dfd, name, &path, lookup_flags);
+ if (IS_ERR(dentry)) {
+ error = PTR_ERR(dentry);
+ goto out;
+ }

if (!IS_POSIXACL(path.dentry->d_inode))
mode &= ~current_umask();
@@ -3676,17 +3682,19 @@ static long do_mkdirat(int dfd, const char __user *pathname, umode_t mode)
lookup_flags |= LOOKUP_REVAL;
goto retry;
}
+out:
+ putname(name);
return error;
}

SYSCALL_DEFINE3(mkdirat, int, dfd, const char __user *, pathname, umode_t, mode)
{
- return do_mkdirat(dfd, pathname, mode);
+ return do_mkdirat(dfd, getname(pathname), mode);
}

SYSCALL_DEFINE2(mkdir, const char __user *, pathname, umode_t, mode)
{
- return do_mkdirat(AT_FDCWD, pathname, mode);
+ return do_mkdirat(AT_FDCWD, getname(pathname), mode);
}

int vfs_rmdir(struct inode *dir, struct dentry *dentry)
--
2.28.0