[PATCH 19/21] init: add an init_mknod helper

From: Christoph Hellwig <hch@lst.de>
To: Al Viro <viro@zeniv.linux.org.uk>,
	Linus Torvalds <torvalds@linux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	linux-kernel@vger.kernel.org, linux-raid@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org
Subject: [PATCH 19/21] init: add an init_mknod helper
Date: Sun, 26 Jul 2020 09:13:54 +0200	[thread overview]
Message-ID: <20200726071356.287160-20-hch@lst.de> (raw)
In-Reply-To: <20200726071356.287160-1-hch@lst.de>

Add a simple helper to mknod with a kernel space file name and switch
the early init code over to it.  Remove the now unused ksys_mknod.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/for_init.c                 | 25 +++++++++++++++++++++++++
 fs/internal.h                 |  2 --
 fs/namei.c                    |  2 +-
 include/linux/init_syscalls.h |  1 +
 include/linux/syscalls.h      |  9 ---------
 init/do_mounts.h              |  2 +-
 init/initramfs.c              |  2 +-
 init/noinitramfs.c            |  3 +--
 8 files changed, 30 insertions(+), 16 deletions(-)

diff --git a/fs/for_init.c b/fs/for_init.c
index 6ae3305bece1eb..50813d2913b57b 100644
--- a/fs/for_init.c
+++ b/fs/for_init.c
@@ -118,6 +118,31 @@ int __init init_eaccess(const char *filename)
 	return error;
 }
 
+int __init init_mknod(const char *filename, umode_t mode, unsigned int dev)
+{
+	struct dentry *dentry;
+	struct path path;
+	int error;
+
+	if (S_ISFIFO(mode) || S_ISSOCK(mode))
+		dev = 0;
+	else if (!(S_ISBLK(mode) || S_ISCHR(mode)))
+		return -EINVAL;
+
+	dentry = kern_path_create(AT_FDCWD, filename, &path, 0);
+	if (IS_ERR(dentry))
+		return PTR_ERR(dentry);
+
+	if (!IS_POSIXACL(path.dentry->d_inode))
+		mode &= ~current_umask();
+	error = security_path_mknod(&path, dentry, mode, dev);
+	if (!error)
+		error = vfs_mknod(path.dentry->d_inode, dentry, mode,
+				  new_decode_dev(dev));
+	done_path_create(&path, dentry);
+	return error;
+}
+
 int __init init_link(const char *oldname, const char *newname)
 {
 	struct dentry *new_dentry;
diff --git a/fs/internal.h b/fs/internal.h
index 4741e591e923bf..07e145b2f88c4a 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -62,8 +62,6 @@ extern int filename_lookup(int dfd, struct filename *name, unsigned flags,
 			   struct path *path, struct path *root);
 extern int vfs_path_lookup(struct dentry *, struct vfsmount *,
 			   const char *, unsigned int, struct path *);
-long do_mknodat(int dfd, const char __user *filename, umode_t mode,
-		unsigned int dev);
 long do_rmdir(int dfd, struct filename *name);
 long do_unlinkat(int dfd, struct filename *name);
 int may_linkat(struct path *link);
diff --git a/fs/namei.c b/fs/namei.c
index d6b25dd32f4d50..fde8fe086c090d 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -3564,7 +3564,7 @@ static int may_mknod(umode_t mode)
 	}
 }
 
-long do_mknodat(int dfd, const char __user *filename, umode_t mode,
+static long do_mknodat(int dfd, const char __user *filename, umode_t mode,
 		unsigned int dev)
 {
 	struct dentry *dentry;
diff --git a/include/linux/init_syscalls.h b/include/linux/init_syscalls.h
index d808985231f8f8..fa1fe7a877795f 100644
--- a/include/linux/init_syscalls.h
+++ b/include/linux/init_syscalls.h
@@ -8,6 +8,7 @@ int __init init_chroot(const char *filename);
 int __init init_chown(const char *filename, uid_t user, gid_t group, int flags);
 int __init init_chmod(const char *filename, umode_t mode);
 int __init init_eaccess(const char *filename);
+int __init init_mknod(const char *filename, umode_t mode, unsigned int dev);
 int __init init_link(const char *oldname, const char *newname);
 int __init init_symlink(const char *oldname, const char *newname);
 int __init init_unlink(const char *pathname);
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 5ef77a91382aa5..63046c5e9fc5d4 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -1270,15 +1270,6 @@ int compat_ksys_ipc(u32 call, int first, int second,
  * The following kernel syscall equivalents are just wrappers to fs-internal
  * functions. Therefore, provide stubs to be inlined at the callsites.
  */
-extern long do_mknodat(int dfd, const char __user *filename, umode_t mode,
-		       unsigned int dev);
-
-static inline long ksys_mknod(const char __user *filename, umode_t mode,
-			      unsigned int dev)
-{
-	return do_mknodat(AT_FDCWD, filename, mode, dev);
-}
-
 extern int do_fchownat(int dfd, const char __user *filename, uid_t user,
 		       gid_t group, int flag);
 
diff --git a/init/do_mounts.h b/init/do_mounts.h
index 104d8431725aeb..7a29ac3e427bab 100644
--- a/init/do_mounts.h
+++ b/init/do_mounts.h
@@ -17,7 +17,7 @@ extern int root_mountflags;
 static inline __init int create_dev(char *name, dev_t dev)
 {
 	init_unlink(name);
-	return ksys_mknod(name, S_IFBLK|0600, new_encode_dev(dev));
+	return init_mknod(name, S_IFBLK | 0600, new_encode_dev(dev));
 }
 
 #ifdef CONFIG_BLK_DEV_RAM
diff --git a/init/initramfs.c b/init/initramfs.c
index 076e66f11bda8d..9b2d93a2eb5e4b 100644
--- a/init/initramfs.c
+++ b/init/initramfs.c
@@ -352,7 +352,7 @@ static int __init do_name(void)
 	} else if (S_ISBLK(mode) || S_ISCHR(mode) ||
 		   S_ISFIFO(mode) || S_ISSOCK(mode)) {
 		if (maybe_link() == 0) {
-			ksys_mknod(collected, mode, rdev);
+			init_mknod(collected, mode, rdev);
 			init_chown(collected, uid, gid, 0);
 			init_chmod(collected, mode);
 			do_utime(collected, mtime);
diff --git a/init/noinitramfs.c b/init/noinitramfs.c
index 94cc4df74b11f2..3d62b07f3bb9c3 100644
--- a/init/noinitramfs.c
+++ b/init/noinitramfs.c
@@ -22,8 +22,7 @@ static int __init default_rootfs(void)
 	if (err < 0)
 		goto out;
 
-	err = ksys_mknod((const char __user __force *) "/dev/console",
-			S_IFCHR | S_IRUSR | S_IWUSR,
+	err = init_mknod("/dev/console", S_IFCHR | S_IRUSR | S_IWUSR,
 			new_encode_dev(MKDEV(5, 1)));
 	if (err < 0)
 		goto out;
-- 
2.27.0

