tools/virtiofsd/passthrough_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 "passthrough_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(fchdir),
  45     SCMP_SYS(fchmod),
  46     SCMP_SYS(fchmodat),
  47     SCMP_SYS(fchownat),
  48     SCMP_SYS(fcntl),
  49     SCMP_SYS(fdatasync),
  50     SCMP_SYS(fgetxattr),
  51     SCMP_SYS(flistxattr),
  52     SCMP_SYS(flock),
  53     SCMP_SYS(fremovexattr),
  54     SCMP_SYS(fsetxattr),
  55     SCMP_SYS(fstat),
  56     SCMP_SYS(fstatfs),
  57     SCMP_SYS(fsync),
  58     SCMP_SYS(ftruncate),
  59     SCMP_SYS(futex),
  60     SCMP_SYS(getdents),
  61     SCMP_SYS(getdents64),
  62     SCMP_SYS(getegid),
  63     SCMP_SYS(geteuid),
  64     SCMP_SYS(getpid),
  65     SCMP_SYS(gettid),
  66     SCMP_SYS(gettimeofday),
  67     SCMP_SYS(getxattr),
  68     SCMP_SYS(linkat),
  69     SCMP_SYS(listxattr),
  70     SCMP_SYS(lseek),
  71     SCMP_SYS(madvise),
  72     SCMP_SYS(mkdirat),
  73     SCMP_SYS(mknodat),
  74     SCMP_SYS(mmap),
  75     SCMP_SYS(mprotect),
  76     SCMP_SYS(mremap),
  77     SCMP_SYS(munmap),
  78     SCMP_SYS(newfstatat),
  79     SCMP_SYS(open),
  80     SCMP_SYS(openat),
  81     SCMP_SYS(ppoll),
  82     SCMP_SYS(prctl), /* TODO restrict to just PR_SET_NAME? */
  83     SCMP_SYS(preadv),
  84     SCMP_SYS(pread64),
  85     SCMP_SYS(pwritev),
  86     SCMP_SYS(pwrite64),
  87     SCMP_SYS(read),
  88     SCMP_SYS(readlinkat),
  89     SCMP_SYS(recvmsg),
  90     SCMP_SYS(renameat),
  91     SCMP_SYS(renameat2),
  92     SCMP_SYS(removexattr),
  93     SCMP_SYS(rt_sigaction),
  94     SCMP_SYS(rt_sigprocmask),
  95     SCMP_SYS(rt_sigreturn),
  96     SCMP_SYS(sched_getattr),
  97     SCMP_SYS(sched_setattr),
  98     SCMP_SYS(sendmsg),
  99     SCMP_SYS(setresgid),
 100     SCMP_SYS(setresuid),
 101 #ifdef __NR_setresgid32
 102     SCMP_SYS(setresgid32),
 103 #endif
 104 #ifdef __NR_setresuid32
 105     SCMP_SYS(setresuid32),
 106 #endif
 107     SCMP_SYS(set_robust_list),
 108     SCMP_SYS(setxattr),
 109     SCMP_SYS(symlinkat),
 110     SCMP_SYS(time), /* Rarely needed, except on static builds */
 111     SCMP_SYS(tgkill),
 112     SCMP_SYS(unlinkat),
 113     SCMP_SYS(unshare),
 114     SCMP_SYS(utimensat),
 115     SCMP_SYS(write),
 116     SCMP_SYS(writev),
 117 };
 118
 119 /* Syscalls used when --syslog is enabled */
 120 static const int syscall_whitelist_syslog[] = {
 121     SCMP_SYS(sendto),
 122 };
 123
 124 static void add_whitelist(scmp_filter_ctx ctx, const int syscalls[], size_t len)
 125 {
 126     size_t i;
 127
 128     for (i = 0; i < len; i++) {
 129         if (seccomp_rule_add(ctx, SCMP_ACT_ALLOW, syscalls[i], 0) != 0) {
 130             fuse_log(FUSE_LOG_ERR, "seccomp_rule_add syscall %d failed\n",
 131                      syscalls[i]);
 132             exit(1);
 133         }
 134     }
 135 }
 136
 137 void setup_seccomp(bool enable_syslog)
 138 {
 139     scmp_filter_ctx ctx;
 140
 141 #ifdef SCMP_ACT_KILL_PROCESS
 142     ctx = seccomp_init(SCMP_ACT_KILL_PROCESS);
 143     /* Handle a newer libseccomp but an older kernel */
 144     if (!ctx && errno == EOPNOTSUPP) {
 145         ctx = seccomp_init(SCMP_ACT_TRAP);
 146     }
 147 #else
 148     ctx = seccomp_init(SCMP_ACT_TRAP);
 149 #endif
 150     if (!ctx) {
 151         fuse_log(FUSE_LOG_ERR, "seccomp_init() failed\n");
 152         exit(1);
 153     }
 154
 155     add_whitelist(ctx, syscall_whitelist, G_N_ELEMENTS(syscall_whitelist));
 156     if (enable_syslog) {
 157         add_whitelist(ctx, syscall_whitelist_syslog,
 158                       G_N_ELEMENTS(syscall_whitelist_syslog));
 159     }
 160
 161     /* libvhost-user calls this for post-copy migration, we don't need it */
 162     if (seccomp_rule_add(ctx, SCMP_ACT_ERRNO(ENOSYS),
 163                          SCMP_SYS(userfaultfd), 0) != 0) {
 164         fuse_log(FUSE_LOG_ERR, "seccomp_rule_add userfaultfd failed\n");
 165         exit(1);
 166     }
 167
 168     if (seccomp_load(ctx) < 0) {
 169         fuse_log(FUSE_LOG_ERR, "seccomp_load() failed\n");
 170         exit(1);
 171     }
 172
 173     seccomp_release(ctx);
 174 }