1 /* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
2 #ifndef _UAPI_LINUX_SECCOMP_H
3 #define _UAPI_LINUX_SECCOMP_H
4 
5 #include <linux/compiler.h>
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 #define SECCOMP_FILTER_FLAG_TSYNC_ESRCH		(1UL << 4)
26 /* Received notifications wait in killable state (only respond to fatal signals) */
27 #define SECCOMP_FILTER_FLAG_WAIT_KILLABLE_RECV	(1UL << 5)
28 
29 /*
30  * All BPF programs must return a 32-bit value.
31  * The bottom 16-bits are for optional return data.
32  * The upper 16-bits are ordered from least permissive values to most,
33  * as a signed value (so 0x8000000 is negative).
34  *
35  * The ordering ensures that a min_t() over composed return values always
36  * selects the least permissive choice.
37  */
38 #define SECCOMP_RET_KILL_PROCESS 0x80000000U /* kill the process */
39 #define SECCOMP_RET_KILL_THREAD	 0x00000000U /* kill the thread */
40 #define SECCOMP_RET_KILL	 SECCOMP_RET_KILL_THREAD
41 #define SECCOMP_RET_TRAP	 0x00030000U /* disallow and force a SIGSYS */
42 #define SECCOMP_RET_ERRNO	 0x00050000U /* returns an errno */
43 #define SECCOMP_RET_USER_NOTIF	 0x7fc00000U /* notifies userspace */
44 #define SECCOMP_RET_TRACE	 0x7ff00000U /* pass to a tracer or disallow */
45 #define SECCOMP_RET_LOG		 0x7ffc0000U /* allow after logging */
46 #define SECCOMP_RET_ALLOW	 0x7fff0000U /* allow */
47 
48 /* Masks for the return value sections. */
49 #define SECCOMP_RET_ACTION_FULL	0xffff0000U
50 #define SECCOMP_RET_ACTION	0x7fff0000U
51 #define SECCOMP_RET_DATA	0x0000ffffU
52 
53 /**
54  * struct seccomp_data - the format the BPF program executes over.
55  * @nr: the system call number
56  * @arch: indicates system call convention as an AUDIT_ARCH_* value
57  *        as defined in <linux/audit.h>.
58  * @instruction_pointer: at the time of the system call.
59  * @args: up to 6 system call arguments always stored as 64-bit values
60  *        regardless of the architecture.
61  */
62 struct seccomp_data {
63 	int nr;
64 	__u32 arch;
65 	__u64 instruction_pointer;
66 	__u64 args[6];
67 };
68 
69 struct seccomp_notif_sizes {
70 	__u16 seccomp_notif;
71 	__u16 seccomp_notif_resp;
72 	__u16 seccomp_data;
73 };
74 
75 struct seccomp_notif {
76 	__u64 id;
77 	__u32 pid;
78 	__u32 flags;
79 	struct seccomp_data data;
80 };
81 
82 /*
83  * Valid flags for struct seccomp_notif_resp
84  *
85  * Note, the SECCOMP_USER_NOTIF_FLAG_CONTINUE flag must be used with caution!
86  * If set by the process supervising the syscalls of another process the
87  * syscall will continue. This is problematic because of an inherent TOCTOU.
88  * An attacker can exploit the time while the supervised process is waiting on
89  * a response from the supervising process to rewrite syscall arguments which
90  * are passed as pointers of the intercepted syscall.
91  * It should be absolutely clear that this means that the seccomp notifier
92  * _cannot_ be used to implement a security policy! It should only ever be used
93  * in scenarios where a more privileged process supervises the syscalls of a
94  * lesser privileged process to get around kernel-enforced security
95  * restrictions when the privileged process deems this safe. In other words,
96  * in order to continue a syscall the supervising process should be sure that
97  * another security mechanism or the kernel itself will sufficiently block
98  * syscalls if arguments are rewritten to something unsafe.
99  *
100  * Similar precautions should be applied when stacking SECCOMP_RET_USER_NOTIF
101  * or SECCOMP_RET_TRACE. For SECCOMP_RET_USER_NOTIF filters acting on the
102  * same syscall, the most recently added filter takes precedence. This means
103  * that the new SECCOMP_RET_USER_NOTIF filter can override any
104  * SECCOMP_IOCTL_NOTIF_SEND from earlier filters, essentially allowing all
105  * such filtered syscalls to be executed by sending the response
106  * SECCOMP_USER_NOTIF_FLAG_CONTINUE. Note that SECCOMP_RET_TRACE can equally
107  * be overriden by SECCOMP_USER_NOTIF_FLAG_CONTINUE.
108  */
109 #define SECCOMP_USER_NOTIF_FLAG_CONTINUE (1UL << 0)
110 
111 struct seccomp_notif_resp {
112 	__u64 id;
113 	__s64 val;
114 	__s32 error;
115 	__u32 flags;
116 };
117 
118 /* valid flags for seccomp_notif_addfd */
119 #define SECCOMP_ADDFD_FLAG_SETFD	(1UL << 0) /* Specify remote fd */
120 #define SECCOMP_ADDFD_FLAG_SEND		(1UL << 1) /* Addfd and return it, atomically */
121 
122 /**
123  * struct seccomp_notif_addfd
124  * @id: The ID of the seccomp notification
125  * @flags: SECCOMP_ADDFD_FLAG_*
126  * @srcfd: The local fd number
127  * @newfd: Optional remote FD number if SETFD option is set, otherwise 0.
128  * @newfd_flags: The O_* flags the remote FD should have applied
129  */
130 struct seccomp_notif_addfd {
131 	__u64 id;
132 	__u32 flags;
133 	__u32 srcfd;
134 	__u32 newfd;
135 	__u32 newfd_flags;
136 };
137 
138 #define SECCOMP_IOC_MAGIC		'!'
139 #define SECCOMP_IO(nr)			_IO(SECCOMP_IOC_MAGIC, nr)
140 #define SECCOMP_IOR(nr, type)		_IOR(SECCOMP_IOC_MAGIC, nr, type)
141 #define SECCOMP_IOW(nr, type)		_IOW(SECCOMP_IOC_MAGIC, nr, type)
142 #define SECCOMP_IOWR(nr, type)		_IOWR(SECCOMP_IOC_MAGIC, nr, type)
143 
144 /* Flags for seccomp notification fd ioctl. */
145 #define SECCOMP_IOCTL_NOTIF_RECV	SECCOMP_IOWR(0, struct seccomp_notif)
146 #define SECCOMP_IOCTL_NOTIF_SEND	SECCOMP_IOWR(1,	\
147 						struct seccomp_notif_resp)
148 #define SECCOMP_IOCTL_NOTIF_ID_VALID	SECCOMP_IOW(2, __u64)
149 /* On success, the return value is the remote process's added fd number */
150 #define SECCOMP_IOCTL_NOTIF_ADDFD	SECCOMP_IOW(3, \
151 						struct seccomp_notif_addfd)
152 
153 #endif /* _UAPI_LINUX_SECCOMP_H */
154