Using the fs-internal do_fchmodat() helper allows us to get rid of fs-internal calls to the sys_fchmodat() syscall. Introducing the ksys_fchmod() helper and the ksys_chmod() wrapper allows us to avoid the in-kernel calls to the sys_fchmod() and sys_chmod() syscalls. The ksys_ prefix denotes that these functions are meant as a drop-in replacement for the syscalls. In particular, they use the same calling convention as sys_fchmod() and sys_chmod(). This patch is part of a series which removes in-kernel calls to syscalls. On this basis, the syscall entry path can be streamlined. For details, see http://lkml.kernel.org/r/20180325162527.GA17492@xxxxxxxxxxxxxxxxxxxxxxxxxx Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Dominik Brodowski <linux@xxxxxxxxxxxxxxxxxxxx> --- fs/internal.h | 2 ++ fs/open.c | 17 ++++++++++++++--- include/linux/syscalls.h | 8 ++++++++ init/initramfs.c | 6 +++--- 4 files changed, 27 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 827ed917630c..dd6c306f4f00 100644 --- a/include/linux/syscalls.h +++ b/include/linux/syscalls.h @@ -953,6 +953,7 @@ int ksys_dup(unsigned int fildes); int ksys_chroot(const char __user *filename); ssize_t ksys_write(unsigned int fd, const char __user *buf, size_t count); int ksys_chdir(const char __user *filename); +int ksys_fchmod(unsigned int fd, umode_t mode); /* * The following kernel syscall equivalents are just wrappers to fs-internal @@ -1006,4 +1007,11 @@ 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); } } -- 2.16.3
