linux-headers (unknown)
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 #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 /* _LINUX_SECCOMP_H */
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