Messages in this thread Patch in this message | | | Date | Wed, 1 Jan 2020 20:05:03 +0100 | From | Dominik Brodowski <> | Subject | [PATCH] Revert "fs: remove ksys_dup()" |
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This reverts commit 8243186f0cc7c57cf9d6a110cd7315c44e3e0be8 and additionally the fix in commit 2d3145f8d2809592ef803a30c8a342b5a9e2de9a.
Trying to use filp_open() and f_dupfd() instead of pseudo-syscalls caused more trouble than what is worth it: it requires accessing vfs internals and causes a strange issue on Androidx86 long after boot.
Reported-by: youling 257 <youling257@gmail.com> Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
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Instead of that (seemingly suboptimal) approach in trying to get the fake __user char out of init/main.c, I'll prepare some patches which have ksys_open() [and a few other ksys_*() functions] operate on kernelspace pointers instead. That will be more compatible with keeping vfs internals internal, and actually move us faster in the direction to let kernel init run with USER_DS. Moreover, that approach doesn't seem to break youling 257's setup.
Thanks, Dominik
diff --git a/fs/file.c b/fs/file.c index 2f4fcf985079..3da91a112bab 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); } -SYSCALL_DEFINE1(dup, unsigned int, fildes) +int ksys_dup(unsigned int fildes) { int ret = -EBADF; struct file *file = fget_raw(fildes); @@ -975,6 +975,11 @@ SYSCALL_DEFINE1(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 2960dedcfde8..5262b7a76d39 100644 --- a/include/linux/syscalls.h +++ b/include/linux/syscalls.h @@ -1232,6 +1232,7 @@ 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 1ecfd43ed464..2cd736059416 100644 --- a/init/main.c +++ b/init/main.c @@ -93,7 +93,6 @@ #include <linux/rodata_test.h> #include <linux/jump_label.h> #include <linux/mem_encrypt.h> -#include <linux/file.h> #include <asm/io.h> #include <asm/bugs.h> @@ -1158,26 +1157,13 @@ static int __ref kernel_init(void *unused) void console_on_rootfs(void) { - struct file *file; - unsigned int i; - - /* Open /dev/console in kernelspace, this should never fail */ - file = filp_open("/dev/console", O_RDWR, 0); - if (IS_ERR(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; + /* 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"); -err_out: - /* no panic -- this might not be fatal */ - pr_err("Warning: unable to open an initial console.\n"); - return; + /* create stdout/stderr */ + (void) ksys_dup(0); + (void) ksys_dup(0); } static noinline void __init kernel_init_freeable(void)
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