[RFC PATCH 31/35] syscalls: do not call sys_{f,}chmod{at,}() within the kernel

[Dominik Brodowski]

CC: Al Viro <v...@zeniv.linux.org.uk>
CC: Andrew Morton <a...@linux-foundation.org>
Signed-off-by: Dominik Brodowski <li...@dominikbrodowski.net>
---
 fs/internal.h            |  2 ++
 fs/open.c                | 17 ++++++++++++++---
 include/linux/syscalls.h |  7 +++++++
 init/initramfs.c         |  6 +++---
 4 files changed, 26 insertions(+), 6 deletions(-)

diff --git a/fs/internal.h b/fs/internal.h
index 91e6fc93fcb5..2474bf460f96 100644
--- a/fs/internal.h
+++ b/fs/internal.h
@@ -119,6 +119,8 @@ extern struct file *do_filp_open(int dfd, struct filename 
*pathname,
 extern struct file *do_file_open_root(struct dentry *, struct vfsmount *,
                const char *, const struct open_flags *);
 
+int do_fchmodat(int dfd, const char __user *filename, umode_t mode);
+
 extern int open_check_o_direct(struct file *f);
 extern int vfs_open(const struct path *, struct file *, const struct cred *);
 extern struct file *filp_clone_open(struct file *);
diff --git a/fs/open.c b/fs/open.c
index a19b8277c439..6037f2bf418c 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -551,7 +551,7 @@ static int chmod_common(const struct path *path, umode_t 
mode)
        return error;
 }
 
-SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode)
+int ksys_fchmod(unsigned int fd, umode_t mode)
 {
        struct fd f = fdget(fd);
        int err = -EBADF;
@@ -564,7 +564,12 @@ SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode)
        return err;
 }
 
-SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename, umode_t, 
mode)
+SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode)
+{
+       return ksys_fchmod(fd, mode);
+}
+
+int do_fchmodat(int dfd, const char __user *filename, umode_t mode)
 {
        struct path path;
        int error;
@@ -582,9 +587,15 @@ SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, 
filename, umode_t, mode
        return error;
 }
 
+SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename,
+               umode_t, mode)
+{
+       return do_fchmodat(dfd, filename, mode);
+}
+
 SYSCALL_DEFINE2(chmod, const char __user *, filename, umode_t, mode)
 {
-       return sys_fchmodat(AT_FDCWD, filename, mode);
+       return do_fchmodat(AT_FDCWD, filename, mode);
 }
 
 static int chown_common(const struct path *path, uid_t user, gid_t group)
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 27620caed7e4..87feef73c077 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -962,6 +962,7 @@ unsigned long ksys_mmap_pgoff(unsigned long addr, unsigned 
long len,
 int ksys_chdir(const char __user *filename);
 int ksys_sync_file_range(int fd, loff_t offset, loff_t nbytes,
                         unsigned int flags);
+int ksys_fchmod(unsigned int fd, umode_t mode);
 
 /*
  * The following kernel syscall equivalents are just wrappers to fs-internal
@@ -1009,4 +1010,10 @@ 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);
+}
+
 #endif
diff --git a/init/initramfs.c b/init/initramfs.c
index 5855ab632b4e..16c3c23076e2 100644
--- a/init/initramfs.c
+++ b/init/initramfs.c
@@ -344,7 +344,7 @@ static int __init do_name(void)
 
                        if (wfd >= 0) {
                                sys_fchown(wfd, uid, gid);
-                               sys_fchmod(wfd, mode);
+                               ksys_fchmod(wfd, mode);
                                if (body_len)
                                        sys_ftruncate(wfd, body_len);
                                vcollected = kstrdup(collected, GFP_KERNEL);
@@ -354,14 +354,14 @@ static int __init do_name(void)
        } else if (S_ISDIR(mode)) {
                ksys_mkdir(collected, mode);
                sys_chown(collected, uid, gid);
-               sys_chmod(collected, mode);
+               ksys_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);
                        sys_chown(collected, uid, gid);
-                       sys_chmod(collected, mode);
+                       ksys_chmod(collected, mode);
                        do_utime(collected, mtime);
                }
        }
-- 
2.16.2