fs: add do_fchownat(), ksys_fchown() helpers and ksys_{,l}chown() wrappers
Using the fs-interal do_fchownat() wrapper allows us to get rid of fs-internal calls to the sys_fchownat() syscall. Introducing the ksys_fchown() helper and the ksys_{,}chown() wrappers allows us to avoid the in-kernel calls to the sys_{,l,f}chown() 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_{,l,f}chown(). 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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@ -89,18 +89,18 @@
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COMPAT_SYSCALL_DEFINE3(s390_chown16, const char __user *, filename,
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u16, user, u16, group)
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{
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return sys_chown(filename, low2highuid(user), low2highgid(group));
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return ksys_chown(filename, low2highuid(user), low2highgid(group));
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}
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COMPAT_SYSCALL_DEFINE3(s390_lchown16, const char __user *,
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filename, u16, user, u16, group)
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{
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return sys_lchown(filename, low2highuid(user), low2highgid(group));
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return ksys_lchown(filename, low2highuid(user), low2highgid(group));
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}
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COMPAT_SYSCALL_DEFINE3(s390_fchown16, unsigned int, fd, u16, user, u16, group)
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{
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return sys_fchown(fd, low2highuid(user), low2highgid(group));
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return ksys_fchown(fd, low2highuid(user), low2highgid(group));
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}
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COMPAT_SYSCALL_DEFINE2(s390_setregid16, u16, rgid, u16, egid)
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@ -121,6 +121,8 @@ extern struct file *do_file_open_root(struct dentry *, struct vfsmount *,
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long do_faccessat(int dfd, const char __user *filename, int mode);
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int do_fchmodat(int dfd, const char __user *filename, umode_t mode);
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int do_fchownat(int dfd, const char __user *filename, uid_t user, gid_t group,
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int flag);
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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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23
fs/open.c
23
fs/open.c
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@ -645,8 +645,8 @@ retry_deleg:
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return error;
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}
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SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user,
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gid_t, group, int, flag)
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int do_fchownat(int dfd, const char __user *filename, uid_t user, gid_t group,
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int flag)
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{
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struct path path;
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int error = -EINVAL;
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@ -677,18 +677,24 @@ out:
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return error;
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}
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SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user,
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gid_t, group, int, flag)
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{
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return do_fchownat(dfd, filename, user, group, flag);
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}
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SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group)
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{
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return sys_fchownat(AT_FDCWD, filename, user, group, 0);
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return do_fchownat(AT_FDCWD, filename, user, group, 0);
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}
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SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group)
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{
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return sys_fchownat(AT_FDCWD, filename, user, group,
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AT_SYMLINK_NOFOLLOW);
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return do_fchownat(AT_FDCWD, filename, user, group,
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AT_SYMLINK_NOFOLLOW);
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}
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SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
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int ksys_fchown(unsigned int fd, uid_t user, gid_t group)
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{
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struct fd f = fdget(fd);
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int error = -EBADF;
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@ -708,6 +714,11 @@ out:
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return error;
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}
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SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group)
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{
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return ksys_fchown(fd, user, group);
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}
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int open_check_o_direct(struct file *f)
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{
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/* NB: we're sure to have correct a_ops only after f_op->open */
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@ -954,6 +954,7 @@ 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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int ksys_fchown(unsigned int fd, uid_t user, gid_t group);
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/*
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* The following kernel syscall equivalents are just wrappers to fs-internal
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@ -1021,4 +1022,20 @@ static inline long ksys_access(const char __user *filename, int mode)
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return do_faccessat(AT_FDCWD, filename, mode);
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}
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extern int do_fchownat(int dfd, const char __user *filename, uid_t user,
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gid_t group, int flag);
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static inline long ksys_chown(const char __user *filename, uid_t user,
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gid_t group)
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{
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return do_fchownat(AT_FDCWD, filename, user, group, 0);
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}
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static inline long ksys_lchown(const char __user *filename, uid_t user,
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gid_t group)
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{
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return do_fchownat(AT_FDCWD, filename, user, group,
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AT_SYMLINK_NOFOLLOW);
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}
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#endif
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@ -343,7 +343,7 @@ static int __init do_name(void)
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wfd = sys_open(collected, openflags, mode);
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if (wfd >= 0) {
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sys_fchown(wfd, uid, gid);
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ksys_fchown(wfd, uid, gid);
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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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@ -353,14 +353,14 @@ static int __init do_name(void)
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}
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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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ksys_chown(collected, uid, gid);
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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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ksys_chown(collected, uid, gid);
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ksys_chmod(collected, mode);
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do_utime(collected, mtime);
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}
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@ -393,7 +393,7 @@ static int __init do_symlink(void)
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collected[N_ALIGN(name_len) + body_len] = '\0';
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clean_path(collected, 0);
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ksys_symlink(collected + N_ALIGN(name_len), collected);
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sys_lchown(collected, uid, gid);
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ksys_lchown(collected, uid, gid);
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do_utime(collected, mtime);
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state = SkipIt;
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next_state = Reset;
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@ -22,17 +22,17 @@
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SYSCALL_DEFINE3(chown16, const char __user *, filename, old_uid_t, user, old_gid_t, group)
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{
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return sys_chown(filename, low2highuid(user), low2highgid(group));
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return ksys_chown(filename, low2highuid(user), low2highgid(group));
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}
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SYSCALL_DEFINE3(lchown16, const char __user *, filename, old_uid_t, user, old_gid_t, group)
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{
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return sys_lchown(filename, low2highuid(user), low2highgid(group));
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return ksys_lchown(filename, low2highuid(user), low2highgid(group));
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}
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SYSCALL_DEFINE3(fchown16, unsigned int, fd, old_uid_t, user, old_gid_t, group)
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{
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return sys_fchown(fd, low2highuid(user), low2highgid(group));
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return ksys_fchown(fd, low2highuid(user), low2highgid(group));
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}
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SYSCALL_DEFINE2(setregid16, old_gid_t, rgid, old_gid_t, egid)
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