1/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
2#ifndef _LINUX_SECCOMP_H
3#define _LINUX_SECCOMP_H
4
5
6#include <linux/types.h>
7
8
9/* Valid values for seccomp.mode and prctl(PR_SET_SECCOMP, <mode>) */
10#define SECCOMP_MODE_DISABLED 0 /* seccomp is not in use. */
11#define SECCOMP_MODE_STRICT 1 /* uses hard-coded filter. */
12#define SECCOMP_MODE_FILTER 2 /* uses user-supplied filter. */
13
14/* Valid operations for seccomp syscall. */
15#define SECCOMP_SET_MODE_STRICT 0
16#define SECCOMP_SET_MODE_FILTER 1
17#define SECCOMP_GET_ACTION_AVAIL 2
18#define SECCOMP_GET_NOTIF_SIZES 3
19
20/* Valid flags for SECCOMP_SET_MODE_FILTER */
21#define SECCOMP_FILTER_FLAG_TSYNC (1UL << 0)
22#define SECCOMP_FILTER_FLAG_LOG (1UL << 1)
23#define SECCOMP_FILTER_FLAG_SPEC_ALLOW (1UL << 2)
24#define SECCOMP_FILTER_FLAG_NEW_LISTENER (1UL << 3)
25
26/*
27 * All BPF programs must return a 32-bit value.
28 * The bottom 16-bits are for optional return data.
29 * The upper 16-bits are ordered from least permissive values to most,
30 * as a signed value (so 0x8000000 is negative).
31 *
32 * The ordering ensures that a min_t() over composed return values always
33 * selects the least permissive choice.
34 */
35#define SECCOMP_RET_KILL_PROCESS 0x80000000U /* kill the process */
36#define SECCOMP_RET_KILL_THREAD 0x00000000U /* kill the thread */
37#define SECCOMP_RET_KILL SECCOMP_RET_KILL_THREAD
38#define SECCOMP_RET_TRAP 0x00030000U /* disallow and force a SIGSYS */
39#define SECCOMP_RET_ERRNO 0x00050000U /* returns an errno */
40#define SECCOMP_RET_USER_NOTIF 0x7fc00000U /* notifies userspace */
41#define SECCOMP_RET_TRACE 0x7ff00000U /* pass to a tracer or disallow */
42#define SECCOMP_RET_LOG 0x7ffc0000U /* allow after logging */
43#define SECCOMP_RET_ALLOW 0x7fff0000U /* allow */
44
45/* Masks for the return value sections. */
46#define SECCOMP_RET_ACTION_FULL 0xffff0000U
47#define SECCOMP_RET_ACTION 0x7fff0000U
48#define SECCOMP_RET_DATA 0x0000ffffU
49
50/**
51 * struct seccomp_data - the format the BPF program executes over.
52 * @nr: the system call number
53 * @arch: indicates system call convention as an AUDIT_ARCH_* value
54 * as defined in <linux/audit.h>.
55 * @instruction_pointer: at the time of the system call.
56 * @args: up to 6 system call arguments always stored as 64-bit values
57 * regardless of the architecture.
58 */
59struct seccomp_data {
60 int nr;
61 __u32 arch;
62 __u64 instruction_pointer;
63 __u64 args[6];
64};
65
66struct seccomp_notif_sizes {
67 __u16 seccomp_notif;
68 __u16 seccomp_notif_resp;
69 __u16 seccomp_data;
70};
71
72struct seccomp_notif {
73 __u64 id;
74 __u32 pid;
75 __u32 flags;
76 struct seccomp_data data;
77};
78
79/*
80 * Valid flags for struct seccomp_notif_resp
81 *
82 * Note, the SECCOMP_USER_NOTIF_FLAG_CONTINUE flag must be used with caution!
83 * If set by the process supervising the syscalls of another process the
84 * syscall will continue. This is problematic because of an inherent TOCTOU.
85 * An attacker can exploit the time while the supervised process is waiting on
86 * a response from the supervising process to rewrite syscall arguments which
87 * are passed as pointers of the intercepted syscall.
88 * It should be absolutely clear that this means that the seccomp notifier
89 * _cannot_ be used to implement a security policy! It should only ever be used
90 * in scenarios where a more privileged process supervises the syscalls of a
91 * lesser privileged process to get around kernel-enforced security
92 * restrictions when the privileged process deems this safe. In other words,
93 * in order to continue a syscall the supervising process should be sure that
94 * another security mechanism or the kernel itself will sufficiently block
95 * syscalls if arguments are rewritten to something unsafe.
96 *
97 * Similar precautions should be applied when stacking SECCOMP_RET_USER_NOTIF
98 * or SECCOMP_RET_TRACE. For SECCOMP_RET_USER_NOTIF filters acting on the
99 * same syscall, the most recently added filter takes precedence. This means
100 * that the new SECCOMP_RET_USER_NOTIF filter can override any
101 * SECCOMP_IOCTL_NOTIF_SEND from earlier filters, essentially allowing all
102 * such filtered syscalls to be executed by sending the response
103 * SECCOMP_USER_NOTIF_FLAG_CONTINUE. Note that SECCOMP_RET_TRACE can equally
104 * be overriden by SECCOMP_USER_NOTIF_FLAG_CONTINUE.
105 */
106#define SECCOMP_USER_NOTIF_FLAG_CONTINUE (1UL << 0)
107
108struct seccomp_notif_resp {
109 __u64 id;
110 __s64 val;
111 __s32 error;
112 __u32 flags;
113};
114
115#define SECCOMP_IOC_MAGIC '!'
116#define SECCOMP_IO(nr) _IO(SECCOMP_IOC_MAGIC, nr)
117#define SECCOMP_IOR(nr, type) _IOR(SECCOMP_IOC_MAGIC, nr, type)
118#define SECCOMP_IOW(nr, type) _IOW(SECCOMP_IOC_MAGIC, nr, type)
119#define SECCOMP_IOWR(nr, type) _IOWR(SECCOMP_IOC_MAGIC, nr, type)
120
121/* Flags for seccomp notification fd ioctl. */
122#define SECCOMP_IOCTL_NOTIF_RECV SECCOMP_IOWR(0, struct seccomp_notif)
123#define SECCOMP_IOCTL_NOTIF_SEND SECCOMP_IOWR(1, \
124 struct seccomp_notif_resp)
125#define SECCOMP_IOCTL_NOTIF_ID_VALID SECCOMP_IOW(2, __u64)
126
127#endif /* _LINUX_SECCOMP_H */
128

source code of include/linux/seccomp.h