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 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 */ 59 struct seccomp_data { 60 int nr; 61 __u32 arch; 62 __u64 instruction_pointer; 63 __u64 args[6]; 64 }; 65 66 struct seccomp_notif_sizes { 67 __u16 seccomp_notif; 68 __u16 seccomp_notif_resp; 69 __u16 seccomp_data; 70 }; 71 72 struct 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) 107 108 struct 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_IOR(2, __u64) 126 #endif /* _UAPI_LINUX_SECCOMP_H */ 127