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