fs: add ksys_fchmod() and do_fchmodat() helpers and ksys_chmod() wrapper; remove in-kernel calls to syscall
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@light.dominikbrodowski.net Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
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@ -119,6 +119,8 @@ extern struct file *do_filp_open(int dfd, struct filename *pathname,
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extern struct file *do_file_open_root(struct dentry *, struct vfsmount *,
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const char *, const struct open_flags *);
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int do_fchmodat(int dfd, const char __user *filename, umode_t mode);
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extern int open_check_o_direct(struct file *f);
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extern int vfs_open(const struct path *, struct file *, const struct cred *);
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extern struct file *filp_clone_open(struct file *);
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17
fs/open.c
17
fs/open.c
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@ -551,7 +551,7 @@ out_unlock:
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return error;
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}
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SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode)
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int ksys_fchmod(unsigned int fd, umode_t mode)
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{
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struct fd f = fdget(fd);
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int err = -EBADF;
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@ -564,7 +564,12 @@ SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode)
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return err;
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}
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SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename, umode_t, mode)
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SYSCALL_DEFINE2(fchmod, unsigned int, fd, umode_t, mode)
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{
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return ksys_fchmod(fd, mode);
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}
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int do_fchmodat(int dfd, const char __user *filename, umode_t mode)
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{
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struct path path;
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int error;
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@ -582,9 +587,15 @@ retry:
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return error;
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}
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SYSCALL_DEFINE3(fchmodat, int, dfd, const char __user *, filename,
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umode_t, mode)
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{
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return do_fchmodat(dfd, filename, mode);
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}
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SYSCALL_DEFINE2(chmod, const char __user *, filename, umode_t, mode)
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{
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return sys_fchmodat(AT_FDCWD, filename, mode);
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return do_fchmodat(AT_FDCWD, filename, mode);
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}
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static int chown_common(const struct path *path, uid_t user, gid_t group)
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@ -953,6 +953,7 @@ int ksys_dup(unsigned int fildes);
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int ksys_chroot(const char __user *filename);
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ssize_t ksys_write(unsigned int fd, const char __user *buf, size_t count);
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int ksys_chdir(const char __user *filename);
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int ksys_fchmod(unsigned int fd, umode_t mode);
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/*
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* The following kernel syscall equivalents are just wrappers to fs-internal
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@ -1006,4 +1007,11 @@ static inline long ksys_link(const char __user *oldname,
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return do_linkat(AT_FDCWD, oldname, AT_FDCWD, newname, 0);
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}
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extern int do_fchmodat(int dfd, const char __user *filename, umode_t mode);
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static inline int ksys_chmod(const char __user *filename, umode_t mode)
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{
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return do_fchmodat(AT_FDCWD, filename, mode);
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}
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#endif
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@ -344,7 +344,7 @@ static int __init do_name(void)
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if (wfd >= 0) {
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sys_fchown(wfd, uid, gid);
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sys_fchmod(wfd, mode);
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ksys_fchmod(wfd, mode);
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if (body_len)
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sys_ftruncate(wfd, body_len);
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vcollected = kstrdup(collected, GFP_KERNEL);
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@ -354,14 +354,14 @@ static int __init do_name(void)
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} else if (S_ISDIR(mode)) {
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ksys_mkdir(collected, mode);
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sys_chown(collected, uid, gid);
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sys_chmod(collected, mode);
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ksys_chmod(collected, mode);
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dir_add(collected, mtime);
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} else if (S_ISBLK(mode) || S_ISCHR(mode) ||
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S_ISFIFO(mode) || S_ISSOCK(mode)) {
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if (maybe_link() == 0) {
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ksys_mknod(collected, mode, rdev);
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sys_chown(collected, uid, gid);
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sys_chmod(collected, mode);
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ksys_chmod(collected, mode);
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do_utime(collected, mtime);
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}
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}
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