tools/virtiofsd/seccomp.c

   1 /*
   2  * Seccomp sandboxing for virtiofsd
   3  *
   4  * Copyright (C) 2019 Red Hat, Inc.
   5  *
   6  * SPDX-License-Identifier: GPL-2.0-or-later
   7  */
   8
   9 #include "qemu/osdep.h"
  10 #include "seccomp.h"
  11 #include "fuse_i.h"
  12 #include "fuse_log.h"
  13 #include <errno.h>
  14 #include <glib.h>
  15 #include <seccomp.h>
  16 #include <stdlib.h>
  17
  18 /* Bodge for libseccomp 2.4.2 which broke ppoll */
  19 #if !defined(__SNR_ppoll) && defined(__SNR_brk)
  20 #ifdef __NR_ppoll
  21 #define __SNR_ppoll __NR_ppoll
  22 #else
  23 #define __SNR_ppoll __PNR_ppoll
  24 #endif
  25 #endif
  26
  27 static const int syscall_whitelist[] = {
  28     /* TODO ireg sem*() syscalls */
  29     SCMP_SYS(brk),
  30     SCMP_SYS(capget), /* For CAP_FSETID */
  31     SCMP_SYS(capset),
  32     SCMP_SYS(clock_gettime),
  33     SCMP_SYS(clone),
  34 #ifdef __NR_clone3
  35     SCMP_SYS(clone3),
  36 #endif
  37     SCMP_SYS(close),
  38     SCMP_SYS(copy_file_range),
  39     SCMP_SYS(dup),
  40     SCMP_SYS(eventfd2),
  41     SCMP_SYS(exit),
  42     SCMP_SYS(exit_group),
  43     SCMP_SYS(fallocate),
  44     SCMP_SYS(fchmodat),
  45     SCMP_SYS(fchownat),
  46     SCMP_SYS(fcntl),
  47     SCMP_SYS(fdatasync),
  48     SCMP_SYS(fgetxattr),
  49     SCMP_SYS(flistxattr),
  50     SCMP_SYS(flock),
  51     SCMP_SYS(fremovexattr),
  52     SCMP_SYS(fsetxattr),
  53     SCMP_SYS(fstat),
  54     SCMP_SYS(fstatfs),
  55     SCMP_SYS(fsync),
  56     SCMP_SYS(ftruncate),
  57     SCMP_SYS(futex),
  58     SCMP_SYS(getdents),
  59     SCMP_SYS(getdents64),
  60     SCMP_SYS(getegid),
  61     SCMP_SYS(geteuid),
  62     SCMP_SYS(getpid),
  63     SCMP_SYS(gettid),
  64     SCMP_SYS(gettimeofday),
  65     SCMP_SYS(linkat),
  66     SCMP_SYS(lseek),
  67     SCMP_SYS(madvise),
  68     SCMP_SYS(mkdirat),
  69     SCMP_SYS(mknodat),
  70     SCMP_SYS(mmap),
  71     SCMP_SYS(mprotect),
  72     SCMP_SYS(mremap),
  73     SCMP_SYS(munmap),
  74     SCMP_SYS(newfstatat),
  75     SCMP_SYS(open),
  76     SCMP_SYS(openat),
  77     SCMP_SYS(ppoll),
  78     SCMP_SYS(prctl), /* TODO restrict to just PR_SET_NAME? */
  79     SCMP_SYS(preadv),
  80     SCMP_SYS(pread64),
  81     SCMP_SYS(pwritev),
  82     SCMP_SYS(pwrite64),
  83     SCMP_SYS(read),
  84     SCMP_SYS(readlinkat),
  85     SCMP_SYS(recvmsg),
  86     SCMP_SYS(renameat),
  87     SCMP_SYS(renameat2),
  88     SCMP_SYS(rt_sigaction),
  89     SCMP_SYS(rt_sigprocmask),
  90     SCMP_SYS(rt_sigreturn),
  91     SCMP_SYS(sendmsg),
  92     SCMP_SYS(setresgid),
  93     SCMP_SYS(setresuid),
  94 #ifdef __NR_setresgid32
  95     SCMP_SYS(setresgid32),
  96 #endif
  97 #ifdef __NR_setresuid32
  98     SCMP_SYS(setresuid32),
  99 #endif
 100     SCMP_SYS(set_robust_list),
 101     SCMP_SYS(symlinkat),
 102     SCMP_SYS(time), /* Rarely needed, except on static builds */
 103     SCMP_SYS(tgkill),
 104     SCMP_SYS(unlinkat),
 105     SCMP_SYS(utimensat),
 106     SCMP_SYS(write),
 107     SCMP_SYS(writev),
 108 };
 109
 110 void setup_seccomp(void)
 111 {
 112     scmp_filter_ctx ctx;
 113     size_t i;
 114
 115 #ifdef SCMP_ACT_KILL_PROCESS
 116     ctx = seccomp_init(SCMP_ACT_KILL_PROCESS);
 117     /* Handle a newer libseccomp but an older kernel */
 118     if (!ctx && errno == EOPNOTSUPP) {
 119         ctx = seccomp_init(SCMP_ACT_TRAP);
 120     }
 121 #else
 122     ctx = seccomp_init(SCMP_ACT_TRAP);
 123 #endif
 124     if (!ctx) {
 125         fuse_log(FUSE_LOG_ERR, "seccomp_init() failed\n");
 126         exit(1);
 127     }
 128
 129     for (i = 0; i < G_N_ELEMENTS(syscall_whitelist); i++) {
 130         if (seccomp_rule_add(ctx, SCMP_ACT_ALLOW,
 131                              syscall_whitelist[i], 0) != 0) {
 132             fuse_log(FUSE_LOG_ERR, "seccomp_rule_add syscall %d",
 133                      syscall_whitelist[i]);
 134             exit(1);
 135         }
 136     }
 137
 138     /* libvhost-user calls this for post-copy migration, we don't need it */
 139     if (seccomp_rule_add(ctx, SCMP_ACT_ERRNO(ENOSYS),
 140                          SCMP_SYS(userfaultfd), 0) != 0) {
 141         fuse_log(FUSE_LOG_ERR, "seccomp_rule_add userfaultfd failed\n");
 142         exit(1);
 143     }
 144
 145     if (seccomp_load(ctx) < 0) {
 146         fuse_log(FUSE_LOG_ERR, "seccomp_load() failed\n");
 147         exit(1);
 148     }
 149
 150     seccomp_release(ctx);
 151 }