From 55731b3cda3a85ee888dac3bf1f36489f275c187 Mon Sep 17 00:00:00 2001 From: Dominik Brodowski Date: Sun, 11 Mar 2018 11:34:55 +0100 Subject: [PATCH] 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 Cc: Andrew Morton Signed-off-by: Dominik Brodowski --- arch/s390/kernel/compat_linux.c | 6 +++--- fs/internal.h | 2 ++ fs/open.c | 23 +++++++++++++++++------ include/linux/syscalls.h | 17 +++++++++++++++++ init/initramfs.c | 8 ++++---- kernel/uid16.c | 6 +++--- 6 files changed, 46 insertions(+), 16 deletions(-) diff --git a/arch/s390/kernel/compat_linux.c b/arch/s390/kernel/compat_linux.c index 5a9cfde5fc28..9a9bb395359c 100644 --- a/arch/s390/kernel/compat_linux.c +++ b/arch/s390/kernel/compat_linux.c @@ -89,18 +89,18 @@ COMPAT_SYSCALL_DEFINE3(s390_chown16, const char __user *, filename, u16, user, u16, group) { - return sys_chown(filename, low2highuid(user), low2highgid(group)); + return ksys_chown(filename, low2highuid(user), low2highgid(group)); } COMPAT_SYSCALL_DEFINE3(s390_lchown16, const char __user *, filename, u16, user, u16, group) { - return sys_lchown(filename, low2highuid(user), low2highgid(group)); + return ksys_lchown(filename, low2highuid(user), low2highgid(group)); } COMPAT_SYSCALL_DEFINE3(s390_fchown16, unsigned int, fd, u16, user, u16, group) { - return sys_fchown(fd, low2highuid(user), low2highgid(group)); + return ksys_fchown(fd, low2highuid(user), low2highgid(group)); } COMPAT_SYSCALL_DEFINE2(s390_setregid16, u16, rgid, u16, egid) diff --git a/fs/internal.h b/fs/internal.h index 26f4f05b52ef..c797480cbd6f 100644 --- a/fs/internal.h +++ b/fs/internal.h @@ -121,6 +121,8 @@ extern struct file *do_file_open_root(struct dentry *, struct vfsmount *, long do_faccessat(int dfd, const char __user *filename, int mode); int do_fchmodat(int dfd, const char __user *filename, umode_t mode); +int do_fchownat(int dfd, const char __user *filename, uid_t user, gid_t group, + int flag); extern int open_check_o_direct(struct file *f); extern int vfs_open(const struct path *, struct file *, const struct cred *); diff --git a/fs/open.c b/fs/open.c index 0fc8188be31a..7b2eccb541f2 100644 --- a/fs/open.c +++ b/fs/open.c @@ -645,8 +645,8 @@ retry_deleg: return error; } -SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user, - gid_t, group, int, flag) +int do_fchownat(int dfd, const char __user *filename, uid_t user, gid_t group, + int flag) { struct path path; int error = -EINVAL; @@ -677,18 +677,24 @@ out: return error; } +SYSCALL_DEFINE5(fchownat, int, dfd, const char __user *, filename, uid_t, user, + gid_t, group, int, flag) +{ + return do_fchownat(dfd, filename, user, group, flag); +} + SYSCALL_DEFINE3(chown, const char __user *, filename, uid_t, user, gid_t, group) { - return sys_fchownat(AT_FDCWD, filename, user, group, 0); + return do_fchownat(AT_FDCWD, filename, user, group, 0); } SYSCALL_DEFINE3(lchown, const char __user *, filename, uid_t, user, gid_t, group) { - return sys_fchownat(AT_FDCWD, filename, user, group, - AT_SYMLINK_NOFOLLOW); + return do_fchownat(AT_FDCWD, filename, user, group, + AT_SYMLINK_NOFOLLOW); } -SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group) +int ksys_fchown(unsigned int fd, uid_t user, gid_t group) { struct fd f = fdget(fd); int error = -EBADF; @@ -708,6 +714,11 @@ out: return error; } +SYSCALL_DEFINE3(fchown, unsigned int, fd, uid_t, user, gid_t, group) +{ + return ksys_fchown(fd, user, group); +} + int open_check_o_direct(struct file *f) { /* NB: we're sure to have correct a_ops only after f_op->open */ diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h index 33f06de090ea..df0d1e818a6e 100644 --- a/include/linux/syscalls.h +++ b/include/linux/syscalls.h @@ -954,6 +954,7 @@ 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); +int ksys_fchown(unsigned int fd, uid_t user, gid_t group); /* * The following kernel syscall equivalents are just wrappers to fs-internal @@ -1021,4 +1022,20 @@ static inline long ksys_access(const char __user *filename, int mode) return do_faccessat(AT_FDCWD, filename, mode); } +extern int do_fchownat(int dfd, const char __user *filename, uid_t user, + gid_t group, int flag); + +static inline long ksys_chown(const char __user *filename, uid_t user, + gid_t group) +{ + return do_fchownat(AT_FDCWD, filename, user, group, 0); +} + +static inline long ksys_lchown(const char __user *filename, uid_t user, + gid_t group) +{ + return do_fchownat(AT_FDCWD, filename, user, group, + AT_SYMLINK_NOFOLLOW); +} + #endif diff --git a/init/initramfs.c b/init/initramfs.c index 16c3c23076e2..35173bef7c00 100644 --- a/init/initramfs.c +++ b/init/initramfs.c @@ -343,7 +343,7 @@ static int __init do_name(void) wfd = sys_open(collected, openflags, mode); if (wfd >= 0) { - sys_fchown(wfd, uid, gid); + ksys_fchown(wfd, uid, gid); ksys_fchmod(wfd, mode); if (body_len) sys_ftruncate(wfd, body_len); @@ -353,14 +353,14 @@ static int __init do_name(void) } } else if (S_ISDIR(mode)) { ksys_mkdir(collected, mode); - sys_chown(collected, uid, gid); + ksys_chown(collected, uid, gid); 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); + ksys_chown(collected, uid, gid); ksys_chmod(collected, mode); do_utime(collected, mtime); } @@ -393,7 +393,7 @@ static int __init do_symlink(void) collected[N_ALIGN(name_len) + body_len] = '\0'; clean_path(collected, 0); ksys_symlink(collected + N_ALIGN(name_len), collected); - sys_lchown(collected, uid, gid); + ksys_lchown(collected, uid, gid); do_utime(collected, mtime); state = SkipIt; next_state = Reset; diff --git a/kernel/uid16.c b/kernel/uid16.c index 7b930edfe461..af6925d8599b 100644 --- a/kernel/uid16.c +++ b/kernel/uid16.c @@ -22,17 +22,17 @@ SYSCALL_DEFINE3(chown16, const char __user *, filename, old_uid_t, user, old_gid_t, group) { - return sys_chown(filename, low2highuid(user), low2highgid(group)); + return ksys_chown(filename, low2highuid(user), low2highgid(group)); } SYSCALL_DEFINE3(lchown16, const char __user *, filename, old_uid_t, user, old_gid_t, group) { - return sys_lchown(filename, low2highuid(user), low2highgid(group)); + return ksys_lchown(filename, low2highuid(user), low2highgid(group)); } SYSCALL_DEFINE3(fchown16, unsigned int, fd, old_uid_t, user, old_gid_t, group) { - return sys_fchown(fd, low2highuid(user), low2highgid(group)); + return ksys_fchown(fd, low2highuid(user), low2highgid(group)); } SYSCALL_DEFINE2(setregid16, old_gid_t, rgid, old_gid_t, egid)