From db63f1e315384590b979f8f74abd1b5363b69894 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Wed, 22 Jul 2020 11:25:21 +0200 Subject: [PATCH] init: add an init_chdir helper Add a simple helper to chdir with a kernel space file name and switch the early init code over to it. Remove the now unused ksys_chdir. Signed-off-by: Christoph Hellwig --- drivers/base/devtmpfs.c | 2 +- fs/init.c | 16 ++++++++++++++++ fs/open.c | 7 +------ include/linux/init_syscalls.h | 1 + include/linux/syscalls.h | 1 - init/do_mounts.c | 2 +- init/do_mounts_initrd.c | 8 ++++---- 7 files changed, 24 insertions(+), 13 deletions(-) diff --git a/drivers/base/devtmpfs.c b/drivers/base/devtmpfs.c index 32af6cb987b4..e48aaba3166b 100644 --- a/drivers/base/devtmpfs.c +++ b/drivers/base/devtmpfs.c @@ -412,7 +412,7 @@ static int __init devtmpfs_setup(void *p) err = init_mount("devtmpfs", "/", "devtmpfs", MS_SILENT, NULL); if (err) goto out; - ksys_chdir("/.."); /* will traverse into overmounted root */ + init_chdir("/.."); /* will traverse into overmounted root */ ksys_chroot("."); out: *(int *)p = err; diff --git a/fs/init.c b/fs/init.c index eabd9ed2b510..64d4e12eba93 100644 --- a/fs/init.c +++ b/fs/init.c @@ -7,6 +7,7 @@ #include #include #include +#include #include #include "internal.h" @@ -38,6 +39,21 @@ int __init init_umount(const char *name, int flags) return path_umount(&path, flags); } +int __init init_chdir(const char *filename) +{ + struct path path; + int error; + + error = kern_path(filename, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &path); + if (error) + return error; + error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR); + if (!error) + set_fs_pwd(current->fs, &path); + path_put(&path); + return error; +} + int __init init_unlink(const char *pathname) { return do_unlinkat(AT_FDCWD, getname_kernel(pathname)); diff --git a/fs/open.c b/fs/open.c index b316dd6a86a8..723e0ac89893 100644 --- a/fs/open.c +++ b/fs/open.c @@ -482,7 +482,7 @@ SYSCALL_DEFINE2(access, const char __user *, filename, int, mode) return do_faccessat(AT_FDCWD, filename, mode, 0); } -int ksys_chdir(const char __user *filename) +SYSCALL_DEFINE1(chdir, const char __user *, filename) { struct path path; int error; @@ -508,11 +508,6 @@ out: return error; } -SYSCALL_DEFINE1(chdir, const char __user *, filename) -{ - return ksys_chdir(filename); -} - SYSCALL_DEFINE1(fchdir, unsigned int, fd) { struct fd f = fdget_raw(fd); diff --git a/include/linux/init_syscalls.h b/include/linux/init_syscalls.h index abf3af563c0b..1e845910ae56 100644 --- a/include/linux/init_syscalls.h +++ b/include/linux/init_syscalls.h @@ -3,5 +3,6 @@ int __init init_mount(const char *dev_name, const char *dir_name, const char *type_page, unsigned long flags, void *data_page); int __init init_umount(const char *name, int flags); +int __init init_chdir(const char *filename); int __init init_unlink(const char *pathname); int __init init_rmdir(const char *pathname); diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h index a7b14258d245..31fa67fb9894 100644 --- a/include/linux/syscalls.h +++ b/include/linux/syscalls.h @@ -1238,7 +1238,6 @@ asmlinkage long sys_ni_syscall(void); 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_fchown(unsigned int fd, uid_t user, gid_t group); ssize_t ksys_read(unsigned int fd, char __user *buf, size_t count); void ksys_sync(void); diff --git a/init/do_mounts.c b/init/do_mounts.c index 83db87b6e5d1..a7581c6e85f2 100644 --- a/init/do_mounts.c +++ b/init/do_mounts.c @@ -408,7 +408,7 @@ static int __init do_mount_root(const char *name, const char *fs, if (ret) goto out; - ksys_chdir("/root"); + init_chdir("/root"); s = current->fs->pwd.dentry->d_sb; ROOT_DEV = s->s_dev; printk(KERN_INFO diff --git a/init/do_mounts_initrd.c b/init/do_mounts_initrd.c index 8b44dd017842..04627fd22a92 100644 --- a/init/do_mounts_initrd.c +++ b/init/do_mounts_initrd.c @@ -61,7 +61,7 @@ static int __init init_linuxrc(struct subprocess_info *info, struct cred *new) ksys_unshare(CLONE_FS | CLONE_FILES); console_on_rootfs(); /* move initrd over / and chdir/chroot in initrd root */ - ksys_chdir("/root"); + init_chdir("/root"); init_mount(".", "/", NULL, MS_MOVE, NULL); ksys_chroot("."); ksys_setsid(); @@ -82,7 +82,7 @@ static void __init handle_initrd(void) /* mount initrd on rootfs' /root */ mount_block_root("/dev/root.old", root_mountflags & ~MS_RDONLY); ksys_mkdir("/old", 0700); - ksys_chdir("/old"); + init_chdir("/old"); /* * In case that a resume from disk is carried out by linuxrc or one of @@ -104,11 +104,11 @@ static void __init handle_initrd(void) ksys_chroot(".."); if (new_decode_dev(real_root_dev) == Root_RAM0) { - ksys_chdir("/old"); + init_chdir("/old"); return; } - ksys_chdir("/"); + init_chdir("/"); ROOT_DEV = new_decode_dev(real_root_dev); mount_root();