Commit f14c234b authored by Aleksa Sarai's avatar Aleksa Sarai Committed by Christian Brauner

clone3: switch to copy_struct_from_user()

Switch clone3() syscall from it's own copying struct clone_args from
userspace to the new dedicated copy_struct_from_user() helper.

The change is very straightforward, and helps unify the syscall
interface for struct-from-userspace syscalls. Additionally, explicitly
define CLONE_ARGS_SIZE_VER0 to match the other users of the
struct-extension pattern.
Signed-off-by: default avatarAleksa Sarai <cyphar@cyphar.com>
Reviewed-by: default avatarKees Cook <keescook@chromium.org>
Reviewed-by: default avatarChristian Brauner <christian.brauner@ubuntu.com>
[christian.brauner@ubuntu.com: improve commit message]
Link: https://lore.kernel.org/r/20191001011055.19283-3-cyphar@cyphar.comSigned-off-by: default avatarChristian Brauner <christian.brauner@ubuntu.com>
parent f5a1a536
...@@ -47,6 +47,8 @@ struct clone_args { ...@@ -47,6 +47,8 @@ struct clone_args {
__aligned_u64 tls; __aligned_u64 tls;
}; };
#define CLONE_ARGS_SIZE_VER0 64 /* sizeof first published struct */
/* /*
* Scheduling policies * Scheduling policies
*/ */
......
...@@ -2525,39 +2525,19 @@ SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp, ...@@ -2525,39 +2525,19 @@ SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp,
#ifdef __ARCH_WANT_SYS_CLONE3 #ifdef __ARCH_WANT_SYS_CLONE3
noinline static int copy_clone_args_from_user(struct kernel_clone_args *kargs, noinline static int copy_clone_args_from_user(struct kernel_clone_args *kargs,
struct clone_args __user *uargs, struct clone_args __user *uargs,
size_t size) size_t usize)
{ {
int err;
struct clone_args args; struct clone_args args;
if (unlikely(size > PAGE_SIZE)) if (unlikely(usize > PAGE_SIZE))
return -E2BIG; return -E2BIG;
if (unlikely(usize < CLONE_ARGS_SIZE_VER0))
if (unlikely(size < sizeof(struct clone_args)))
return -EINVAL; return -EINVAL;
if (unlikely(!access_ok(uargs, size))) err = copy_struct_from_user(&args, sizeof(args), uargs, usize);
return -EFAULT; if (err)
return err;
if (size > sizeof(struct clone_args)) {
unsigned char __user *addr;
unsigned char __user *end;
unsigned char val;
addr = (void __user *)uargs + sizeof(struct clone_args);
end = (void __user *)uargs + size;
for (; addr < end; addr++) {
if (get_user(val, addr))
return -EFAULT;
if (val)
return -E2BIG;
}
size = sizeof(struct clone_args);
}
if (copy_from_user(&args, uargs, size))
return -EFAULT;
/* /*
* Verify that higher 32bits of exit_signal are unset and that * Verify that higher 32bits of exit_signal are unset and that
......
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