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seccomp: switch system call argument type to void *

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The const qualifier causes problems for any code that wants to write to the
third argument of the seccomp syscall, as we will do in a future patch in
this series.

The third argument to the seccomp syscall is documented as void *, so
rather than just dropping the const, let's switch everything to use void *
as well.

I believe this is safe because of 1. the documentation above, 2. there's no
real type information exported about syscalls anywhere besides the man
pages.

Signed-off-by: Tycho Andersen <tycho@tycho.ws>
CC: Kees Cook <keescook@chromium.org>
CC: Andy Lutomirski <luto@amacapital.net>
CC: Oleg Nesterov <oleg@redhat.com>
CC: Eric W. Biederman <ebiederm@xmission.com>
CC: "Serge E. Hallyn" <serge@hallyn.com>
Acked-by: Serge Hallyn <serge@hallyn.com>
CC: Christian Brauner <christian@brauner.io>
CC: Tyler Hicks <tyhicks@canonical.com>
CC: Akihiro Suda <suda.akihiro@lab.ntt.co.jp>
Signed-off-by: Kees Cook <keescook@chromium.org>
This commit is contained in:
Tycho Andersen 2018-12-09 11:24:12 -07:00 committed by Kees Cook
parent db5113911a
commit a5662e4d81
3 changed files with 6 additions and 6 deletions
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2
include/linux/seccomp.h
View File

@ -43,7 +43,7 @@ extern void secure_computing_strict(int this_syscall);
#endif
extern long prctl_get_seccomp(void);
extern long prctl_set_seccomp(unsigned long, char __user *);
extern long prctl_set_seccomp(unsigned long, void __user *);
static inline int seccomp_mode(struct seccomp *s)
{

2
include/linux/syscalls.h
View File

@ -879,7 +879,7 @@ asmlinkage long sys_renameat2(int olddfd, const char __user *oldname,
int newdfd, const char __user *newname,
unsigned int flags);
asmlinkage long sys_seccomp(unsigned int op, unsigned int flags,
const char __user *uargs);
void __user *uargs);
asmlinkage long sys_getrandom(char __user *buf, size_t count,
unsigned int flags);
asmlinkage long sys_memfd_create(const char __user *uname_ptr, unsigned int flags);

8
kernel/seccomp.c
View File

@ -924,7 +924,7 @@ static long seccomp_get_action_avail(const char __user *uaction)
/* Common entry point for both prctl and syscall. */
static long do_seccomp(unsigned int op, unsigned int flags,
const char __user *uargs)
void __user *uargs)
{
switch (op) {
case SECCOMP_SET_MODE_STRICT:
@ -944,7 +944,7 @@ static long do_seccomp(unsigned int op, unsigned int flags,
}
SYSCALL_DEFINE3(seccomp, unsigned int, op, unsigned int, flags,
const char __user *, uargs)
void __user *, uargs)
{
return do_seccomp(op, flags, uargs);
}
@ -956,10 +956,10 @@ SYSCALL_DEFINE3(seccomp, unsigned int, op, unsigned int, flags,
*
* Returns 0 on success or -EINVAL on failure.
*/
long prctl_set_seccomp(unsigned long seccomp_mode, char __user *filter)
long prctl_set_seccomp(unsigned long seccomp_mode, void __user *filter)
{
unsigned int op;
char __user *uargs;
void __user *uargs;
switch (seccomp_mode) {
case SECCOMP_MODE_STRICT: