[PATCH 11/24] fs: add a kern_chmod helper

[Christoph Hellwig]

Add a simple helper to chown with a kernel space name and use it in the
early init code instead of relying on the implicit set_fs(KERNEL_DS)
there.  Remove the now unused ksys_chmod.

Signed-off-by: Christoph Hellwig <h...@lst.de>
---
 fs/internal.h            |  1 -
 fs/open.c                | 28 +++++++++++++++++-----------
 include/linux/fs.h       |  1 +
 include/linux/syscalls.h |  7 -------
 init/initramfs.c         |  4 ++--
 5 files changed, 20 insertions(+), 21 deletions(-)

diff --git a/fs/internal.h b/fs/internal.h
index ad62729e7ae587..1e2b425f56ee9e 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -126,7 +126,6 @@ extern struct open_how build_open_how(int flags, umode_t 
mode);
 extern int build_open_flags(const struct open_how *how, struct open_flags *op);
 
 long do_sys_ftruncate(unsigned int fd, loff_t length, int small);
-int do_fchmodat(int dfd, const char __user *filename, umode_t mode);
 
 extern int vfs_open(const struct path *, struct file *);
 
diff --git a/fs/open.c b/fs/open.c
index 8157db254c8f8a..bb8ffc24c4b034 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -643,33 +643,39 @@ SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode)
        return err;
 }
 
-int do_fchmodat(int dfd, const char __user *filename, umode_t mode)
+static int do_fchmodat(int dfd, struct filename *name, umode_t mode)
 {
        struct path path;
        int error;
        unsigned int lookup_flags = LOOKUP_FOLLOW;
 retry:
-       error = user_path_at(dfd, filename, lookup_flags, &path);
-       if (!error) {
-               error = chmod_common(&path, mode);
-               path_put(&path);
-               if (retry_estale(error, lookup_flags)) {
-                       lookup_flags |= LOOKUP_REVAL;
-                       goto retry;
-               }
+       error = filename_lookup(dfd, name, lookup_flags, &path, NULL);
+       if (error)
+               return error;
+       error = chmod_common(&path, mode);
+       path_put(&path);
+       if (retry_estale(error, lookup_flags)) {
+               lookup_flags |= LOOKUP_REVAL;
+               goto retry;
        }
+       putname(name);
        return error;
 }
 
+int __init kern_chmod(const char *filename, umode_t mode)
+{
+       return do_fchmodat(AT_FDCWD, getname_kernel(filename), mode);
+}
+
 SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename,
                umode_t, mode)
 {
-       return do_fchmodat(dfd, filename, mode);
+       return do_fchmodat(dfd, getname(filename), mode);
 }
 
 SYSCALL_DEFINE2(chmod, const char __user *, filename, umode_t, mode)
 {
-       return do_fchmodat(AT_FDCWD, filename, mode);
+       return do_fchmodat(AT_FDCWD, getname(filename), mode);
 }
 
 static int chown_common(const struct path *path, uid_t user, gid_t group)
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 75d6ef7e1de52b..ca034126cb0e4d 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3675,5 +3675,6 @@ int kern_chdir(const char *filename);
 int kern_chroot(const char *filename);
 int __init kern_access(const char *filename, int mode);
 int __init kern_chown(const char *filename, uid_t user, gid_t group, int flag);
+int __init kern_chmod(const char *filename, umode_t mode);
 
 #endif /* _LINUX_FS_H */
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 82346a68a73877..a2ece4cc8692f5 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -1318,13 +1318,6 @@ static inline long ksys_link(const char __user *oldname,
        return do_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0);
 }
 
-extern int do_fchmodat(int dfd, const char __user *filename, umode_t mode);
-
-static inline int ksys_chmod(const char __user *filename, umode_t mode)
-{
-       return do_fchmodat(AT_FDCWD, filename, mode);
-}
-
 extern long do_sys_ftruncate(unsigned int fd, loff_t length, int small);
 
 static inline long ksys_ftruncate(unsigned int fd, loff_t length)
diff --git a/init/initramfs.c b/init/initramfs.c
index 45e4ddb63caba1..2c2d4480d495e8 100644
--- a/init/initramfs.c
+++ b/init/initramfs.c
@@ -346,14 +346,14 @@ static int __init do_name(void)
        } else if (S_ISDIR(mode)) {
                ksys_mkdir(collected, mode);
                kern_chown(collected, uid, gid, 0);
-               ksys_chmod(collected, mode);
+               kern_chmod(collected, mode);
                dir_add(collected, mtime);
        } else if (S_ISBLK(mode) || S_ISCHR(mode) ||
                   S_ISFIFO(mode) || S_ISSOCK(mode)) {
                if (maybe_link() == 0) {
                        ksys_mknod(collected, mode, rdev);
                        kern_chown(collected, uid, gid, 0);
-                       ksys_chmod(collected, mode);
+                       kern_chmod(collected, mode);
                        do_utime(collected, mtime);
                }
        }
-- 
2.27.0