include/uapi/linux/seccomp.h

   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 #define SECCOMP_USER_NOTIF_FD_SYNC_WAKE_UP (1UL << 0)
 119
 120 /* valid flags for seccomp_notif_addfd */
 121 #define SECCOMP_ADDFD_FLAG_SETFD        (1UL << 0) /* Specify remote fd */
 122 #define SECCOMP_ADDFD_FLAG_SEND         (1UL << 1) /* Addfd and return it, atomically */
 123
 124 /**
 125  * struct seccomp_notif_addfd
 126  * @id: The ID of the seccomp notification
 127  * @flags: SECCOMP_ADDFD_FLAG_*
 128  * @srcfd: The local fd number
 129  * @newfd: Optional remote FD number if SETFD option is set, otherwise 0.
 130  * @newfd_flags: The O_* flags the remote FD should have applied
 131  */
 132 struct seccomp_notif_addfd {
 133         __u64 id;
 134         __u32 flags;
 135         __u32 srcfd;
 136         __u32 newfd;
 137         __u32 newfd_flags;
 138 };
 139
 140 #define SECCOMP_IOC_MAGIC               '!'
 141 #define SECCOMP_IO(nr)                  _IO(SECCOMP_IOC_MAGIC, nr)
 142 #define SECCOMP_IOR(nr, type)           _IOR(SECCOMP_IOC_MAGIC, nr, type)
 143 #define SECCOMP_IOW(nr, type)           _IOW(SECCOMP_IOC_MAGIC, nr, type)
 144 #define SECCOMP_IOWR(nr, type)          _IOWR(SECCOMP_IOC_MAGIC, nr, type)
 145
 146 /* Flags for seccomp notification fd ioctl. */
 147 #define SECCOMP_IOCTL_NOTIF_RECV        SECCOMP_IOWR(0, struct seccomp_notif)
 148 #define SECCOMP_IOCTL_NOTIF_SEND        SECCOMP_IOWR(1, \
 149                                                 struct seccomp_notif_resp)
 150 #define SECCOMP_IOCTL_NOTIF_ID_VALID    SECCOMP_IOW(2, __u64)
 151 /* On success, the return value is the remote process's added fd number */
 152 #define SECCOMP_IOCTL_NOTIF_ADDFD       SECCOMP_IOW(3, \
 153                                                 struct seccomp_notif_addfd)
 154
 155 #define SECCOMP_IOCTL_NOTIF_SET_FLAGS   SECCOMP_IOW(4, __u64)
 156
 157 #endif /* _UAPI_LINUX_SECCOMP_H */