From cccaa5e33525fc07f4a2ce0518e50b9ddf435e47 Mon Sep 17 00:00:00 2001 From: Dominik Brodowski Date: Tue, 23 Oct 2018 22:41:09 +0200 Subject: init: use do_mount() instead of ksys_mount() In prepare_namespace(), do_mount() can be used instead of ksys_mount() as the first and third argument are const strings in the kernel, the second and fourth argument are passed through anyway, and the fifth argument is NULL. In do_mount_root(), ksys_mount() is called with the first and third argument being already kernelspace strings, which do not need to be copied over from userspace to kernelspace (again). The second and fourth arguments are passed through to do_mount() anyway. The fifth argument, while already residing in kernelspace, needs to be put into a page of its own. Then, do_mount() can be used instead of ksys_mount(). Once this is done, there are no in-kernel users to ksys_mount() left, which can therefore be removed. Signed-off-by: Dominik Brodowski --- fs/namespace.c | 10 ++-------- 1 file changed, 2 insertions(+), 8 deletions(-) (limited to 'fs') diff --git a/fs/namespace.c b/fs/namespace.c index 2fd0c8bcb8c1..be601d3a8008 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -3325,8 +3325,8 @@ struct dentry *mount_subtree(struct vfsmount *m, const char *name) } EXPORT_SYMBOL(mount_subtree); -int ksys_mount(const char __user *dev_name, const char __user *dir_name, - const char __user *type, unsigned long flags, void __user *data) +SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name, + char __user *, type, unsigned long, flags, void __user *, data) { int ret; char *kernel_type; @@ -3359,12 +3359,6 @@ out_type: return ret; } -SYSCALL_DEFINE5(mount, char __user *, dev_name, char __user *, dir_name, - char __user *, type, unsigned long, flags, void __user *, data) -{ - return ksys_mount(dev_name, dir_name, type, flags, data); -} - /* * Create a kernel mount representation for a new, prepared superblock * (specified by fs_fd) and attach to an open_tree-like file descriptor. -- cgit v1.2.3 From 8243186f0cc7c57cf9d6a110cd7315c44e3e0be8 Mon Sep 17 00:00:00 2001 From: Dominik Brodowski Date: Tue, 23 Oct 2018 16:24:09 +0200 Subject: fs: remove ksys_dup() ksys_dup() is used only at one place in the kernel, namely to duplicate fd 0 of /dev/console to stdout and stderr. The same functionality can be achieved by using functions already available within the kernel namespace. Signed-off-by: Dominik Brodowski --- fs/file.c | 7 +------ include/linux/syscalls.h | 1 - init/main.c | 26 ++++++++++++++++++++------ 3 files changed, 21 insertions(+), 13 deletions(-) (limited to 'fs') diff --git a/fs/file.c b/fs/file.c index 3da91a112bab..2f4fcf985079 100644 --- a/fs/file.c +++ b/fs/file.c @@ -960,7 +960,7 @@ SYSCALL_DEFINE2(dup2, unsigned int, oldfd, unsigned int, newfd) return ksys_dup3(oldfd, newfd, 0); } -int ksys_dup(unsigned int fildes) +SYSCALL_DEFINE1(dup, unsigned int, fildes) { int ret = -EBADF; struct file *file = fget_raw(fildes); @@ -975,11 +975,6 @@ int ksys_dup(unsigned int fildes) return ret; } -SYSCALL_DEFINE1(dup, unsigned int, fildes) -{ - return ksys_dup(fildes); -} - int f_dupfd(unsigned int from, struct file *file, unsigned flags) { int err; diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h index 5262b7a76d39..2960dedcfde8 100644 --- a/include/linux/syscalls.h +++ b/include/linux/syscalls.h @@ -1232,7 +1232,6 @@ asmlinkage long sys_ni_syscall(void); */ int ksys_umount(char __user *name, int flags); -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); diff --git a/init/main.c b/init/main.c index 2cd736059416..ec3a1463ac69 100644 --- a/init/main.c +++ b/init/main.c @@ -93,6 +93,7 @@ #include #include #include +#include #include #include @@ -1157,13 +1158,26 @@ static int __ref kernel_init(void *unused) void console_on_rootfs(void) { - /* Open the /dev/console as stdin, this should never fail */ - if (ksys_open((const char __user *) "/dev/console", O_RDWR, 0) < 0) - pr_err("Warning: unable to open an initial console.\n"); + struct file *file; + unsigned int i; + + /* Open /dev/console in kernelspace, this should never fail */ + file = filp_open("/dev/console", O_RDWR, 0); + if (!file) + goto err_out; + + /* create stdin/stdout/stderr, this should never fail */ + for (i = 0; i < 3; i++) { + if (f_dupfd(i, file, 0) != i) + goto err_out; + } + + return; - /* create stdout/stderr */ - (void) ksys_dup(0); - (void) ksys_dup(0); +err_out: + /* no panic -- this might not be fatal */ + pr_err("Warning: unable to open an initial console.\n"); + return; } static noinline void __init kernel_init_freeable(void) -- cgit v1.2.3