[RFC PATCH 3/7] lib/cpio: use non __init filesystem related functions

[Jonathan McDowell]

In preparation for making the cpio functions generally available rather
than just at init make sure we're using versions of the filesystem
related functions that aren't in the __init section. Remove functions
only used by us from fs/init.c while folding into the cpio code
directly.

Signed-off-by: Jonathan McDowell <noodles@xxxxxx>
---
 fs/init.c                     | 101 ----------------------
 fs/internal.h                 |   4 -
 include/linux/fs.h            |   4 +
 include/linux/init_syscalls.h |   6 --
 lib/cpio.c                    | 156 +++++++++++++++++++++++++++++-----
 5 files changed, 139 insertions(+), 132 deletions(-)

diff --git a/fs/init.c b/fs/init.c
index 5c36adaa9b44..a946ad672dee 100644
--- a/fs/init.c
+++ b/fs/init.c
@@ -79,37 +79,6 @@ int __init init_chroot(const char *filename)
 	return error;
 }
 
-int __init init_chown(const char *filename, uid_t user, gid_t group, int flags)
-{
-	int lookup_flags = (flags & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
-	struct path path;
-	int error;
-
-	error = kern_path(filename, lookup_flags, &path);
-	if (error)
-		return error;
-	error = mnt_want_write(path.mnt);
-	if (!error) {
-		error = chown_common(&path, user, group);
-		mnt_drop_write(path.mnt);
-	}
-	path_put(&path);
-	return error;
-}
-
-int __init init_chmod(const char *filename, umode_t mode)
-{
-	struct path path;
-	int error;
-
-	error = kern_path(filename, LOOKUP_FOLLOW, &path);
-	if (error)
-		return error;
-	error = chmod_common(&path, mode);
-	path_put(&path);
-	return error;
-}
-
 int __init init_eaccess(const char *filename)
 {
 	struct path path;
@@ -163,58 +132,6 @@ int __init init_mknod(const char *filename, umode_t mode, unsigned int dev)
 	return error;
 }
 
-int __init init_link(const char *oldname, const char *newname)
-{
-	struct dentry *new_dentry;
-	struct path old_path, new_path;
-	struct user_namespace *mnt_userns;
-	int error;
-
-	error = kern_path(oldname, 0, &old_path);
-	if (error)
-		return error;
-
-	new_dentry = kern_path_create(AT_FDCWD, newname, &new_path, 0);
-	error = PTR_ERR(new_dentry);
-	if (IS_ERR(new_dentry))
-		goto out;
-
-	error = -EXDEV;
-	if (old_path.mnt != new_path.mnt)
-		goto out_dput;
-	mnt_userns = mnt_user_ns(new_path.mnt);
-	error = may_linkat(mnt_userns, &old_path);
-	if (unlikely(error))
-		goto out_dput;
-	error = security_path_link(old_path.dentry, &new_path, new_dentry);
-	if (error)
-		goto out_dput;
-	error = vfs_link(old_path.dentry, mnt_userns, new_path.dentry->d_inode,
-			 new_dentry, NULL);
-out_dput:
-	done_path_create(&new_path, new_dentry);
-out:
-	path_put(&old_path);
-	return error;
-}
-
-int __init init_symlink(const char *oldname, const char *newname)
-{
-	struct dentry *dentry;
-	struct path path;
-	int error;
-
-	dentry = kern_path_create(AT_FDCWD, newname, &path, 0);
-	if (IS_ERR(dentry))
-		return PTR_ERR(dentry);
-	error = security_path_symlink(&path, dentry, oldname);
-	if (!error)
-		error = vfs_symlink(mnt_user_ns(path.mnt), path.dentry->d_inode,
-				    dentry, oldname);
-	done_path_create(&path, dentry);
-	return error;
-}
-
 int __init init_unlink(const char *pathname)
 {
 	return do_unlinkat(AT_FDCWD, getname_kernel(pathname));
@@ -239,24 +156,6 @@ int __init init_mkdir(const char *pathname, umode_t mode)
 	return error;
 }
 
-int __init init_rmdir(const char *pathname)
-{
-	return do_rmdir(AT_FDCWD, getname_kernel(pathname));
-}
-
-int __init init_utimes(char *filename, struct timespec64 *ts)
-{
-	struct path path;
-	int error;
-
-	error = kern_path(filename, 0, &path);
-	if (error)
-		return error;
-	error = vfs_utimes(&path, ts);
-	path_put(&path);
-	return error;
-}
-
 int __init init_dup(struct file *file)
 {
 	int fd;
diff --git a/fs/internal.h b/fs/internal.h
index 87e96b9024ce..c57d5f0aa731 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -60,9 +60,6 @@ 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 *);
-int do_rmdir(int dfd, struct filename *name);
-int do_unlinkat(int dfd, struct filename *name);
-int may_linkat(struct user_namespace *mnt_userns, struct path *link);
 int do_renameat2(int olddfd, struct filename *oldname, int newdfd,
 		 struct filename *newname, unsigned int flags);
 int do_mkdirat(int dfd, struct filename *name, umode_t mode);
@@ -132,7 +129,6 @@ long do_sys_ftruncate(unsigned int fd, loff_t length, int small);
 int chmod_common(const struct path *path, umode_t mode);
 int do_fchownat(int dfd, const char __user *filename, uid_t user, gid_t group,
 		int flag);
-int chown_common(const struct path *path, uid_t user, gid_t group);
 extern int vfs_open(const struct path *, struct file *);
 
 /*
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 9ad5e3520fae..1cb51a54799b 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2636,11 +2636,15 @@ static inline struct file *file_clone_open(struct file *file)
 	return dentry_open(&file->f_path, file->f_flags, file->f_cred);
 }
 extern int filp_close(struct file *, fl_owner_t id);
+extern int chown_common(const struct path *path, uid_t user, gid_t group);
 
+extern int do_rmdir(int dfd, struct filename *name);
+extern int do_unlinkat(int dfd, struct filename *name);
 extern struct filename *getname_flags(const char __user *, int, int *);
 extern struct filename *getname_uflags(const char __user *, int);
 extern struct filename *getname(const char __user *);
 extern struct filename *getname_kernel(const char *);
+extern int may_linkat(struct user_namespace *mnt_userns, struct path *link);
 extern void putname(struct filename *name);
 
 extern int finish_open(struct file *file, struct dentry *dentry,
diff --git a/include/linux/init_syscalls.h b/include/linux/init_syscalls.h
index 92045d18cbfc..196030cd958d 100644
--- a/include/linux/init_syscalls.h
+++ b/include/linux/init_syscalls.h
@@ -5,15 +5,9 @@ int __init init_mount(const char *dev_name, const char *dir_name,
 int __init init_umount(const char *name, int flags);
 int __init init_chdir(const char *filename);
 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_stat(const char *filename, struct kstat *stat, int flags);
 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);
 int __init init_mkdir(const char *pathname, umode_t mode);
-int __init init_rmdir(const char *pathname);
-int __init init_utimes(char *filename, struct timespec64 *ts);
 int __init init_dup(struct file *file);
diff --git a/lib/cpio.c b/lib/cpio.c
index 5d150939704f..6ae443a1c103 100644
--- a/lib/cpio.c
+++ b/lib/cpio.c
@@ -3,8 +3,9 @@
 #include <linux/file.h>
 #include <linux/fs.h>
 #include <linux/init.h>
-#include <linux/init_syscalls.h>
 #include <linux/list.h>
+#include <linux/namei.h>
+#include <linux/security.h>
 #include <linux/slab.h>
 
 static ssize_t __init xwrite(struct cpio_context *ctx, struct file *file,
@@ -92,18 +93,25 @@ static void __init free_hash(struct cpio_context *ctx)
 }
 
 #ifdef CONFIG_INITRAMFS_PRESERVE_MTIME
-static void __init do_utime(char *filename, time64_t mtime)
+static void __init do_utime_path(const struct path *path, time64_t mtime)
 {
 	struct timespec64 t[2] = { { .tv_sec = mtime }, { .tv_sec = mtime } };
 
-	init_utimes(filename, t);
+	vfs_utimes(path, t);
 }
 
-static void __init do_utime_path(const struct path *path, time64_t mtime)
+static int __init do_utime(char *filename, time64_t mtime)
 {
-	struct timespec64 t[2] = { { .tv_sec = mtime }, { .tv_sec = mtime } };
+	struct path path;
+	int error;
 
-	vfs_utimes(path, t);
+	error = kern_path(filename, 0, &path);
+	if (error)
+		return error;
+	do_utime_path(&path, mtime);
+	path_put(&path);
+
+	return error;
 }
 
 static int __init dir_add(struct cpio_context *ctx, const char *name, time64_t mtime)
@@ -133,12 +141,31 @@ static void __init dir_utime(struct cpio_context *ctx)
 	}
 }
 #else
-static void __init do_utime(char *filename, time64_t mtime) {}
+static int __init do_utime(char *filename, time64_t mtime) { return 0; }
 static void __init do_utime_path(const struct path *path, time64_t mtime) {}
 static int __init dir_add(struct cpio_context *ctx, const char *name, time64_t mtime) { return 0; }
 static void __init dir_utime(struct cpio_context *ctx) {}
 #endif
 
+static int __init cpio_chown(const char *filename, uid_t user, gid_t group,
+			     int flags)
+{
+	int lookup_flags = (flags & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
+	struct path path;
+	int error;
+
+	error = kern_path(filename, lookup_flags, &path);
+	if (error)
+		return error;
+	error = mnt_want_write(path.mnt);
+	if (!error) {
+		error = chown_common(&path, user, group);
+		mnt_drop_write(path.mnt);
+	}
+	path_put(&path);
+	return error;
+}
+
 /* cpio header parsing */
 
 static void __init parse_header(struct cpio_context *ctx, char *s)
@@ -269,27 +296,67 @@ static int __init do_reset(struct cpio_context *ctx)
 	return 1;
 }
 
-static void __init clean_path(char *path, umode_t fmode)
+static void __init clean_path(char *pathname, umode_t fmode)
 {
+	struct path path;
 	struct kstat st;
+	int error;
 
-	if (!init_stat(path, &st, AT_SYMLINK_NOFOLLOW) &&
-	    (st.mode ^ fmode) & S_IFMT) {
+	error = kern_path(pathname, 0, &path);
+	if (error)
+		return;
+	error = vfs_getattr(&path, &st, STATX_BASIC_STATS, AT_NO_AUTOMOUNT);
+	path_put(&path);
+	if (error)
+		return;
+
+	if ((st.mode ^ fmode) & S_IFMT) {
 		if (S_ISDIR(st.mode))
-			init_rmdir(path);
+			do_rmdir(AT_FDCWD, getname_kernel(pathname));
 		else
-			init_unlink(path);
+			do_unlinkat(AT_FDCWD, getname_kernel(pathname));
 	}
 }
 
 static int __init maybe_link(struct cpio_context *ctx)
 {
+	struct dentry *new_dentry;
+	struct path old_path, new_path;
+	struct user_namespace *mnt_userns;
+	int error;
+
 	if (ctx->nlink >= 2) {
 		char *old = find_link(ctx, ctx->major, ctx->minor, ctx->ino,
 				ctx->mode, ctx->collected);
 		if (old) {
 			clean_path(ctx->collected, 0);
-			return (init_link(old, ctx->collected) < 0) ? -1 : 1;
+
+			error = kern_path(old, 0, &old_path);
+			if (error)
+				return error;
+
+			new_dentry = kern_path_create(AT_FDCWD, ctx->collected, &new_path, 0);
+			error = PTR_ERR(new_dentry);
+			if (IS_ERR(new_dentry))
+				goto out;
+
+			error = -EXDEV;
+			if (old_path.mnt != new_path.mnt)
+				goto out_dput;
+			mnt_userns = mnt_user_ns(new_path.mnt);
+			error = may_linkat(mnt_userns, &old_path);
+			if (unlikely(error))
+				goto out_dput;
+			error = security_path_link(old_path.dentry, &new_path, new_dentry);
+			if (error)
+				goto out_dput;
+			error = vfs_link(old_path.dentry, mnt_userns, new_path.dentry->d_inode,
+					 new_dentry, NULL);
+out_dput:
+			done_path_create(&new_path, new_dentry);
+out:
+			path_put(&old_path);
+			return (error < 0) ? error : 1;
 		}
 	}
 	return 0;
@@ -297,6 +364,10 @@ static int __init maybe_link(struct cpio_context *ctx)
 
 static int __init do_name(struct cpio_context *ctx)
 {
+	struct dentry *dentry;
+	struct path path;
+	int error;
+
 	ctx->state = CPIO_SKIPIT;
 	ctx->next_state = CPIO_RESET;
 	if (strcmp(ctx->collected, "TRAILER!!!") == 0) {
@@ -325,16 +396,42 @@ static int __init do_name(struct cpio_context *ctx)
 			ctx->state = CPIO_COPYFILE;
 		}
 	} else if (S_ISDIR(ctx->mode)) {
-		init_mkdir(ctx->collected, ctx->mode);
-		init_chown(ctx->collected, ctx->uid, ctx->gid, 0);
-		init_chmod(ctx->collected, ctx->mode);
+		dentry = kern_path_create(AT_FDCWD, ctx->collected, &path, LOOKUP_DIRECTORY);
+		if (IS_ERR(dentry))
+			return PTR_ERR(dentry);
+		error = security_path_mkdir(&path, dentry, ctx->mode);
+		if (!error)
+			error = vfs_mkdir(mnt_user_ns(path.mnt), path.dentry->d_inode,
+					  dentry, ctx->mode);
+		done_path_create(&path, dentry);
+		if (error)
+			return error;
+
+		cpio_chown(ctx->collected, ctx->uid, ctx->gid, 0);
 		dir_add(ctx, ctx->collected, ctx->mtime);
 	} else if (S_ISBLK(ctx->mode) || S_ISCHR(ctx->mode) ||
 		   S_ISFIFO(ctx->mode) || S_ISSOCK(ctx->mode)) {
 		if (maybe_link(ctx) == 0) {
-			init_mknod(ctx->collected, ctx->mode, ctx->rdev);
-			init_chown(ctx->collected, ctx->uid, ctx->gid, 0);
-			init_chmod(ctx->collected, ctx->mode);
+			if (S_ISFIFO(ctx->mode) || S_ISSOCK(ctx->mode))
+				ctx->rdev = 0;
+
+			dentry = kern_path_create(AT_FDCWD, ctx->collected, &path, 0);
+			if (IS_ERR(dentry))
+				return PTR_ERR(dentry);
+
+			error = security_path_mknod(&path, dentry, ctx->mode,
+						    ctx->rdev);
+			if (!error)
+				error = vfs_mknod(mnt_user_ns(path.mnt),
+						  path.dentry->d_inode,
+						  dentry, ctx->mode,
+						  new_decode_dev(ctx->rdev));
+			done_path_create(&path, dentry);
+
+			if (error)
+				return error;
+
+			cpio_chown(ctx->collected, ctx->uid, ctx->gid, 0);
 			do_utime(ctx->collected, ctx->mtime);
 		}
 	}
@@ -373,10 +470,27 @@ static int __init do_copy(struct cpio_context *ctx)
 
 static int __init do_symlink(struct cpio_context *ctx)
 {
+	struct dentry *dentry;
+	struct path path;
+	int error;
+
 	ctx->collected[N_ALIGN(ctx->name_len) + ctx->body_len] = '\0';
 	clean_path(ctx->collected, 0);
-	init_symlink(ctx->collected + N_ALIGN(ctx->name_len), ctx->collected);
-	init_chown(ctx->collected, ctx->uid, ctx->gid, AT_SYMLINK_NOFOLLOW);
+
+	dentry = kern_path_create(AT_FDCWD, ctx->collected, &path, 0);
+	if (IS_ERR(dentry))
+		return PTR_ERR(dentry);
+	error = security_path_symlink(&path, dentry,
+				      ctx->collected + N_ALIGN(ctx->name_len));
+	if (!error)
+		error = vfs_symlink(mnt_user_ns(path.mnt), path.dentry->d_inode,
+				    dentry,
+				    ctx->collected + N_ALIGN(ctx->name_len));
+	done_path_create(&path, dentry);
+	if (error)
+		return error;
+
+	cpio_chown(ctx->collected, ctx->uid, ctx->gid, AT_SYMLINK_NOFOLLOW);
 	do_utime(ctx->collected, ctx->mtime);
 	ctx->state = CPIO_SKIPIT;
 	ctx->next_state = CPIO_RESET;
-- 
2.36.1