linux_dsm_epyc7002/include/uapi/linux/seccomp.h
Christian Brauner 23b2c96fad seccomp: rework define for SECCOMP_USER_NOTIF_FLAG_CONTINUE
Switch from BIT(0) to (1UL << 0).
First, there are already two different forms used in the header, so there's
no need to add a third. Second, the BIT() macros is kernel internal and
afaict not actually exposed to userspace. Maybe there's some magic there
I'm missing but it definitely causes issues when compiling a program that
tries to use SECCOMP_USER_NOTIF_FLAG_CONTINUE. It currently fails in the
following way:

	# github.com/lxc/lxd/lxd
	/usr/bin/ld: $WORK/b001/_x003.o: in function
	`__do_user_notification_continue':
	lxd/main_checkfeature.go:240: undefined reference to `BIT'
	collect2: error: ld returned 1 exit status

Switching to (1UL << 0) should prevent that and is more in line what is
already done in the rest of the header.

Cc: Kees Cook <keescook@chromium.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Link: https://lore.kernel.org/r/20191024212539.4059-1-christian.brauner@ubuntu.com
Signed-off-by: Kees Cook <keescook@chromium.org>
2019-10-28 12:29:46 -07:00

127 lines
4.9 KiB
C

/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
#ifndef _UAPI_LINUX_SECCOMP_H
#define _UAPI_LINUX_SECCOMP_H
#include <linux/compiler.h>
#include <linux/types.h>
/* Valid values for seccomp.mode and prctl(PR_SET_SECCOMP, <mode>) */
#define SECCOMP_MODE_DISABLED 0 /* seccomp is not in use. */
#define SECCOMP_MODE_STRICT 1 /* uses hard-coded filter. */
#define SECCOMP_MODE_FILTER 2 /* uses user-supplied filter. */
/* Valid operations for seccomp syscall. */
#define SECCOMP_SET_MODE_STRICT 0
#define SECCOMP_SET_MODE_FILTER 1
#define SECCOMP_GET_ACTION_AVAIL 2
#define SECCOMP_GET_NOTIF_SIZES 3
/* Valid flags for SECCOMP_SET_MODE_FILTER */
#define SECCOMP_FILTER_FLAG_TSYNC (1UL << 0)
#define SECCOMP_FILTER_FLAG_LOG (1UL << 1)
#define SECCOMP_FILTER_FLAG_SPEC_ALLOW (1UL << 2)
#define SECCOMP_FILTER_FLAG_NEW_LISTENER (1UL << 3)
/*
* All BPF programs must return a 32-bit value.
* The bottom 16-bits are for optional return data.
* The upper 16-bits are ordered from least permissive values to most,
* as a signed value (so 0x8000000 is negative).
*
* The ordering ensures that a min_t() over composed return values always
* selects the least permissive choice.
*/
#define SECCOMP_RET_KILL_PROCESS 0x80000000U /* kill the process */
#define SECCOMP_RET_KILL_THREAD 0x00000000U /* kill the thread */
#define SECCOMP_RET_KILL SECCOMP_RET_KILL_THREAD
#define SECCOMP_RET_TRAP 0x00030000U /* disallow and force a SIGSYS */
#define SECCOMP_RET_ERRNO 0x00050000U /* returns an errno */
#define SECCOMP_RET_USER_NOTIF 0x7fc00000U /* notifies userspace */
#define SECCOMP_RET_TRACE 0x7ff00000U /* pass to a tracer or disallow */
#define SECCOMP_RET_LOG 0x7ffc0000U /* allow after logging */
#define SECCOMP_RET_ALLOW 0x7fff0000U /* allow */
/* Masks for the return value sections. */
#define SECCOMP_RET_ACTION_FULL 0xffff0000U
#define SECCOMP_RET_ACTION 0x7fff0000U
#define SECCOMP_RET_DATA 0x0000ffffU
/**
* struct seccomp_data - the format the BPF program executes over.
* @nr: the system call number
* @arch: indicates system call convention as an AUDIT_ARCH_* value
* as defined in <linux/audit.h>.
* @instruction_pointer: at the time of the system call.
* @args: up to 6 system call arguments always stored as 64-bit values
* regardless of the architecture.
*/
struct seccomp_data {
int nr;
__u32 arch;
__u64 instruction_pointer;
__u64 args[6];
};
struct seccomp_notif_sizes {
__u16 seccomp_notif;
__u16 seccomp_notif_resp;
__u16 seccomp_data;
};
struct seccomp_notif {
__u64 id;
__u32 pid;
__u32 flags;
struct seccomp_data data;
};
/*
* Valid flags for struct seccomp_notif_resp
*
* Note, the SECCOMP_USER_NOTIF_FLAG_CONTINUE flag must be used with caution!
* If set by the process supervising the syscalls of another process the
* syscall will continue. This is problematic because of an inherent TOCTOU.
* An attacker can exploit the time while the supervised process is waiting on
* a response from the supervising process to rewrite syscall arguments which
* are passed as pointers of the intercepted syscall.
* It should be absolutely clear that this means that the seccomp notifier
* _cannot_ be used to implement a security policy! It should only ever be used
* in scenarios where a more privileged process supervises the syscalls of a
* lesser privileged process to get around kernel-enforced security
* restrictions when the privileged process deems this safe. In other words,
* in order to continue a syscall the supervising process should be sure that
* another security mechanism or the kernel itself will sufficiently block
* syscalls if arguments are rewritten to something unsafe.
*
* Similar precautions should be applied when stacking SECCOMP_RET_USER_NOTIF
* or SECCOMP_RET_TRACE. For SECCOMP_RET_USER_NOTIF filters acting on the
* same syscall, the most recently added filter takes precedence. This means
* that the new SECCOMP_RET_USER_NOTIF filter can override any
* SECCOMP_IOCTL_NOTIF_SEND from earlier filters, essentially allowing all
* such filtered syscalls to be executed by sending the response
* SECCOMP_USER_NOTIF_FLAG_CONTINUE. Note that SECCOMP_RET_TRACE can equally
* be overriden by SECCOMP_USER_NOTIF_FLAG_CONTINUE.
*/
#define SECCOMP_USER_NOTIF_FLAG_CONTINUE (1UL << 0)
struct seccomp_notif_resp {
__u64 id;
__s64 val;
__s32 error;
__u32 flags;
};
#define SECCOMP_IOC_MAGIC '!'
#define SECCOMP_IO(nr) _IO(SECCOMP_IOC_MAGIC, nr)
#define SECCOMP_IOR(nr, type) _IOR(SECCOMP_IOC_MAGIC, nr, type)
#define SECCOMP_IOW(nr, type) _IOW(SECCOMP_IOC_MAGIC, nr, type)
#define SECCOMP_IOWR(nr, type) _IOWR(SECCOMP_IOC_MAGIC, nr, type)
/* Flags for seccomp notification fd ioctl. */
#define SECCOMP_IOCTL_NOTIF_RECV SECCOMP_IOWR(0, struct seccomp_notif)
#define SECCOMP_IOCTL_NOTIF_SEND SECCOMP_IOWR(1, \
struct seccomp_notif_resp)
#define SECCOMP_IOCTL_NOTIF_ID_VALID SECCOMP_IOR(2, __u64)
#endif /* _UAPI_LINUX_SECCOMP_H */