linux-stable/include/linux/seccomp.h
Tycho Andersen 51891498f2 seccomp: allow TSYNC and USER_NOTIF together
The restriction introduced in 7a0df7fbc1 ("seccomp: Make NEW_LISTENER and
TSYNC flags exclusive") is mostly artificial: there is enough information
in a seccomp user notification to tell which thread triggered a
notification. The reason it was introduced is because TSYNC makes the
syscall return a thread-id on failure, and NEW_LISTENER returns an fd, and
there's no way to distinguish between these two cases (well, I suppose the
caller could check all fds it has, then do the syscall, and if the return
value was an fd that already existed, then it must be a thread id, but
bleh).

Matthew would like to use these two flags together in the Chrome sandbox
which wants to use TSYNC for video drivers and NEW_LISTENER to proxy
syscalls.

So, let's fix this ugliness by adding another flag, TSYNC_ESRCH, which
tells the kernel to just return -ESRCH on a TSYNC error. This way,
NEW_LISTENER (and any subsequent seccomp() commands that want to return
positive values) don't conflict with each other.

Suggested-by: Matthew Denton <mpdenton@google.com>
Signed-off-by: Tycho Andersen <tycho@tycho.ws>
Link: https://lore.kernel.org/r/20200304180517.23867-1-tycho@tycho.ws
Signed-off-by: Kees Cook <keescook@chromium.org>
2020-03-04 14:48:54 -08:00

116 lines
2.9 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_SECCOMP_H
#define _LINUX_SECCOMP_H
#include <uapi/linux/seccomp.h>
#define SECCOMP_FILTER_FLAG_MASK (SECCOMP_FILTER_FLAG_TSYNC | \
SECCOMP_FILTER_FLAG_LOG | \
SECCOMP_FILTER_FLAG_SPEC_ALLOW | \
SECCOMP_FILTER_FLAG_NEW_LISTENER | \
SECCOMP_FILTER_FLAG_TSYNC_ESRCH)
#ifdef CONFIG_SECCOMP
#include <linux/thread_info.h>
#include <asm/seccomp.h>
struct seccomp_filter;
/**
* struct seccomp - the state of a seccomp'ed process
*
* @mode: indicates one of the valid values above for controlled
* system calls available to a process.
* @filter: must always point to a valid seccomp-filter or NULL as it is
* accessed without locking during system call entry.
*
* @filter must only be accessed from the context of current as there
* is no read locking.
*/
struct seccomp {
int mode;
struct seccomp_filter *filter;
};
#ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER
extern int __secure_computing(const struct seccomp_data *sd);
static inline int secure_computing(void)
{
if (unlikely(test_thread_flag(TIF_SECCOMP)))
return __secure_computing(NULL);
return 0;
}
#else
extern void secure_computing_strict(int this_syscall);
#endif
extern long prctl_get_seccomp(void);
extern long prctl_set_seccomp(unsigned long, void __user *);
static inline int seccomp_mode(struct seccomp *s)
{
return s->mode;
}
#else /* CONFIG_SECCOMP */
#include <linux/errno.h>
struct seccomp { };
struct seccomp_filter { };
#ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER
static inline int secure_computing(void) { return 0; }
#else
static inline void secure_computing_strict(int this_syscall) { return; }
#endif
static inline long prctl_get_seccomp(void)
{
return -EINVAL;
}
static inline long prctl_set_seccomp(unsigned long arg2, char __user *arg3)
{
return -EINVAL;
}
static inline int seccomp_mode(struct seccomp *s)
{
return SECCOMP_MODE_DISABLED;
}
#endif /* CONFIG_SECCOMP */
#ifdef CONFIG_SECCOMP_FILTER
extern void put_seccomp_filter(struct task_struct *tsk);
extern void get_seccomp_filter(struct task_struct *tsk);
#else /* CONFIG_SECCOMP_FILTER */
static inline void put_seccomp_filter(struct task_struct *tsk)
{
return;
}
static inline void get_seccomp_filter(struct task_struct *tsk)
{
return;
}
#endif /* CONFIG_SECCOMP_FILTER */
#if defined(CONFIG_SECCOMP_FILTER) && defined(CONFIG_CHECKPOINT_RESTORE)
extern long seccomp_get_filter(struct task_struct *task,
unsigned long filter_off, void __user *data);
extern long seccomp_get_metadata(struct task_struct *task,
unsigned long filter_off, void __user *data);
#else
static inline long seccomp_get_filter(struct task_struct *task,
unsigned long n, void __user *data)
{
return -EINVAL;
}
static inline long seccomp_get_metadata(struct task_struct *task,
unsigned long filter_off,
void __user *data)
{
return -EINVAL;
}
#endif /* CONFIG_SECCOMP_FILTER && CONFIG_CHECKPOINT_RESTORE */
#endif /* _LINUX_SECCOMP_H */