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 <seccomp.h>
  14
  15 /* Bodge for libseccomp 2.4.2 which broke ppoll */
  16 #if !defined(__SNR_ppoll) && defined(__SNR_brk)
  17 #ifdef __NR_ppoll
  18 #define __SNR_ppoll __NR_ppoll
  19 #else
  20 #define __SNR_ppoll __PNR_ppoll
  21 #endif
  22 #endif
  23
  24 static const int syscall_whitelist[] = {
  25     /* TODO ireg sem*() syscalls */
  26     SCMP_SYS(brk),
  27     SCMP_SYS(capget), /* For CAP_FSETID */
  28     SCMP_SYS(capset),
  29     SCMP_SYS(clock_gettime),
  30     SCMP_SYS(clone),
  31 #ifdef __NR_clone3
  32     SCMP_SYS(clone3),
  33 #endif
  34     SCMP_SYS(close),
  35     SCMP_SYS(copy_file_range),
  36     SCMP_SYS(dup),
  37     SCMP_SYS(eventfd2),
  38     SCMP_SYS(exit),
  39     SCMP_SYS(exit_group),
  40     SCMP_SYS(fallocate),
  41     SCMP_SYS(fchdir),
  42     SCMP_SYS(fchmod),
  43     SCMP_SYS(fchmodat),
  44     SCMP_SYS(fchownat),
  45     SCMP_SYS(fcntl),
  46     SCMP_SYS(fdatasync),
  47     SCMP_SYS(fgetxattr),
  48     SCMP_SYS(flistxattr),
  49     SCMP_SYS(flock),
  50     SCMP_SYS(fremovexattr),
  51     SCMP_SYS(fsetxattr),
  52     SCMP_SYS(fstat),
  53     SCMP_SYS(fstatfs),
  54     SCMP_SYS(fsync),
  55     SCMP_SYS(ftruncate),
  56     SCMP_SYS(futex),
  57     SCMP_SYS(getdents),
  58     SCMP_SYS(getdents64),
  59     SCMP_SYS(getegid),
  60     SCMP_SYS(geteuid),
  61     SCMP_SYS(getpid),
  62     SCMP_SYS(gettid),
  63     SCMP_SYS(gettimeofday),
  64     SCMP_SYS(getxattr),
  65     SCMP_SYS(linkat),
  66     SCMP_SYS(listxattr),
  67     SCMP_SYS(lseek),
  68     SCMP_SYS(madvise),
  69     SCMP_SYS(mkdirat),
  70     SCMP_SYS(mknodat),
  71     SCMP_SYS(mmap),
  72     SCMP_SYS(mprotect),
  73     SCMP_SYS(mremap),
  74     SCMP_SYS(munmap),
  75     SCMP_SYS(newfstatat),
  76     SCMP_SYS(statx),
  77     SCMP_SYS(open),
  78     SCMP_SYS(openat),
  79     SCMP_SYS(ppoll),
  80     SCMP_SYS(prctl), /* TODO restrict to just PR_SET_NAME? */
  81     SCMP_SYS(preadv),
  82     SCMP_SYS(pread64),
  83     SCMP_SYS(pwritev),
  84     SCMP_SYS(pwrite64),
  85     SCMP_SYS(read),
  86     SCMP_SYS(readlinkat),
  87     SCMP_SYS(recvmsg),
  88     SCMP_SYS(renameat),
  89     SCMP_SYS(renameat2),
  90     SCMP_SYS(removexattr),
  91     SCMP_SYS(rt_sigaction),
  92     SCMP_SYS(rt_sigprocmask),
  93     SCMP_SYS(rt_sigreturn),
  94     SCMP_SYS(sched_getattr),
  95     SCMP_SYS(sched_setattr),
  96     SCMP_SYS(sendmsg),
  97     SCMP_SYS(setresgid),
  98     SCMP_SYS(setresuid),
  99 #ifdef __NR_setresgid32
 100     SCMP_SYS(setresgid32),
 101 #endif
 102 #ifdef __NR_setresuid32
 103     SCMP_SYS(setresuid32),
 104 #endif
 105     SCMP_SYS(set_robust_list),
 106     SCMP_SYS(setxattr),
 107     SCMP_SYS(symlinkat),
 108     SCMP_SYS(time), /* Rarely needed, except on static builds */
 109     SCMP_SYS(tgkill),
 110     SCMP_SYS(unlinkat),
 111     SCMP_SYS(unshare),
 112     SCMP_SYS(utimensat),
 113     SCMP_SYS(write),
 114     SCMP_SYS(writev),
 115 };
 116
 117 /* Syscalls used when --syslog is enabled */
 118 static const int syscall_whitelist_syslog[] = {
 119     SCMP_SYS(send),
 120     SCMP_SYS(sendto),
 121 };
 122
 123 static void add_whitelist(scmp_filter_ctx ctx, const int syscalls[], size_t len)
 124 {
 125     size_t i;
 126
 127     for (i = 0; i < len; i++) {
 128         if (seccomp_rule_add(ctx, SCMP_ACT_ALLOW, syscalls[i], 0) != 0) {
 129             fuse_log(FUSE_LOG_ERR, "seccomp_rule_add syscall %d failed\n",
 130                      syscalls[i]);
 131             exit(1);
 132         }
 133     }
 134 }
 135
 136 void setup_seccomp(bool enable_syslog)
 137 {
 138     scmp_filter_ctx ctx;
 139
 140 #ifdef SCMP_ACT_KILL_PROCESS
 141     ctx = seccomp_init(SCMP_ACT_KILL_PROCESS);
 142     /* Handle a newer libseccomp but an older kernel */
 143     if (!ctx && errno == EOPNOTSUPP) {
 144         ctx = seccomp_init(SCMP_ACT_TRAP);
 145     }
 146 #else
 147     ctx = seccomp_init(SCMP_ACT_TRAP);
 148 #endif
 149     if (!ctx) {
 150         fuse_log(FUSE_LOG_ERR, "seccomp_init() failed\n");
 151         exit(1);
 152     }
 153
 154     add_whitelist(ctx, syscall_whitelist, G_N_ELEMENTS(syscall_whitelist));
 155     if (enable_syslog) {
 156         add_whitelist(ctx, syscall_whitelist_syslog,
 157                       G_N_ELEMENTS(syscall_whitelist_syslog));
 158     }
 159
 160     /* libvhost-user calls this for post-copy migration, we don't need it */
 161     if (seccomp_rule_add(ctx, SCMP_ACT_ERRNO(ENOSYS),
 162                          SCMP_SYS(userfaultfd), 0) != 0) {
 163         fuse_log(FUSE_LOG_ERR, "seccomp_rule_add userfaultfd failed\n");
 164         exit(1);
 165     }
 166
 167     if (seccomp_load(ctx) < 0) {
 168         fuse_log(FUSE_LOG_ERR, "seccomp_load() failed\n");
 169         exit(1);
 170     }
 171
 172     seccomp_release(ctx);
 173 }