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  • Committer: teddy at recompile
  • Date: 2020-04-05 21:30:59 UTC
  • Revision ID: teddy@recompile.se-20200405213059-fb2a61ckqynrmatk
Fix file descriptor leak in mandos-client

When the local network has Mandos servers announcing themselves using
real, globally reachable, IPv6 addresses (i.e. not link-local
addresses), but there is no router on the local network providing IPv6
RA (Router Advertisement) packets, the client cannot reach the server
by normal means, since the client only has a link-local IPv6 address,
and has no usable route to reach the server's global IPv6 address.
(This is not a common situation, and usually only happens when the
router itself reboots and runs a Mandos client, since it cannot then
give RA packets to itself.)  The client code has a solution for
this, which consists of adding a temporary local route to reach the
address of the server during communication, and removing this
temporary route afterwards.

This solution with a temporary route works, but has a file descriptor
leak; it leaks one file descriptor for each addition and for each
removal of a route.  If one server requiring an added route is present
on the network, but no servers gives a password, making the client
retry after the default ten seconds, and we furthermore assume a
default 1024 open files limit, the client runs out of file descriptors
after about 90 minutes, after which time the client process will be
useless and fail to retrieve any passwords, necessitating manual
password entry via the keyboard.

Fix this by eliminating the file descriptor leak in the client.

* plugins.d/mandos-client.c (add_delete_local_route): Do
  close(devnull) also in parent process, also if fork() fails, and on
  any failure in child process.

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Lines of Context:
plugins.d/mandos-client.c
9
9
 * "browse_callback", and parts of "main".
10
10
 * 
11
11
 * Everything else is
12
 
 * Copyright © 2008-2021 Teddy Hogeborn
13
 
 * Copyright © 2008-2021 Björn Påhlsson
 
12
 * Copyright © 2008-2019 Teddy Hogeborn
 
13
 * Copyright © 2008-2019 Björn Påhlsson
14
14
 * 
15
15
 * This file is part of Mandos.
16
16
 * 
38
38
#define _FILE_OFFSET_BITS 64
39
39
#endif  /* not _FILE_OFFSET_BITS */
40
40
 
41
 
#define _GNU_SOURCE             /* program_invocation_short_name,
42
 
                                   TEMP_FAILURE_RETRY(), O_CLOEXEC,
43
 
                                   scandirat(), asprintf() */
 
41
#define _GNU_SOURCE             /* TEMP_FAILURE_RETRY(), asprintf() */
 
42
 
 
43
#include <stdio.h>              /* fprintf(), stderr, fwrite(),
 
44
                                   stdout, ferror() */
 
45
#include <stdint.h>             /* uint16_t, uint32_t, intptr_t */
 
46
#include <stddef.h>             /* NULL, size_t, ssize_t */
 
47
#include <stdlib.h>             /* free(), EXIT_SUCCESS, srand(),
 
48
                                   strtof(), abort() */
44
49
#include <stdbool.h>            /* bool, false, true */
45
 
#include <argp.h>               /* argp_program_version,
46
 
                                   argp_program_bug_address,
47
 
                                   struct argp_option,
48
 
                                   struct argp_state, argp_error(),
49
 
                                   argp_state_help,
50
 
                                   ARGP_HELP_STD_HELP,
51
 
                                   ARGP_HELP_EXIT_ERR,
52
 
                                   ARGP_HELP_EXIT_OK, ARGP_HELP_USAGE,
53
 
                                   argp_err_exit_status,
54
 
                                   ARGP_ERR_UNKNOWN, struct argp,
55
 
                                   argp_parse(), ARGP_IN_ORDER,
56
 
                                   ARGP_NO_HELP */
57
 
#include <stddef.h>             /* NULL, size_t */
58
 
#include <sys/types.h>          /* uid_t, gid_t, sig_atomic_t,
59
 
                                   seteuid(), setuid(), pid_t,
60
 
                                   setgid(), getuid(), getgid() */
61
 
#include <unistd.h>             /* uid_t, gid_t, TEMP_FAILURE_RETRY(),
62
 
                                   seteuid(), setuid(), close(),
63
 
                                   ssize_t, read(), fork(), setgid(),
64
 
                                   _exit(), dup2(), STDIN_FILENO,
65
 
                                   STDERR_FILENO, STDOUT_FILENO,
66
 
                                   fexecve(), write(), getuid(),
67
 
                                   getgid(), fchown(), symlink(),
68
 
                                   sleep(), unlinkat(), pause() */
69
 
#include <netinet/in.h>         /* in_port_t, struct sockaddr_in6,
70
 
                                   sa_family_t, struct sockaddr_in,
71
 
                                   htons(), IN6_IS_ADDR_LINKLOCAL,
72
 
                                   INET_ADDRSTRLEN, INET6_ADDRSTRLEN,
73
 
                                   ntohl(), IPPROTO_IP */
74
 
#include <time.h>               /* struct timespec, clock_gettime(),
75
 
                                   CLOCK_MONOTONIC, time_t, struct tm,
76
 
                                   gmtime_r(), clock_settime(),
77
 
                                   CLOCK_REALTIME, nanosleep() */
78
 
#include <errno.h>              /* errno,
79
 
                                   program_invocation_short_name,
80
 
                                   EINTR, EINVAL, ENETUNREACH,
 
50
#include <string.h>             /* strcmp(), strlen(), strerror(),
 
51
                                   asprintf(), strncpy(), strsignal()
 
52
                                */
 
53
#include <sys/ioctl.h>          /* ioctl */
 
54
#include <sys/types.h>          /* socket(), inet_pton(), sockaddr,
 
55
                                   sockaddr_in6, PF_INET6,
 
56
                                   SOCK_STREAM, uid_t, gid_t, open(),
 
57
                                   opendir(), DIR */
 
58
#include <sys/stat.h>           /* open(), S_ISREG */
 
59
#include <sys/socket.h>         /* socket(), struct sockaddr_in6,
 
60
                                   inet_pton(), connect(),
 
61
                                   getnameinfo() */
 
62
#include <fcntl.h>              /* open(), unlinkat(), AT_REMOVEDIR */
 
63
#include <dirent.h>             /* opendir(), struct dirent, readdir()
 
64
                                 */
 
65
#include <inttypes.h>           /* PRIu16, PRIdMAX, intmax_t,
 
66
                                   strtoimax() */
 
67
#include <errno.h>              /* perror(), errno, EINTR, EINVAL,
 
68
                                   EAI_SYSTEM, ENETUNREACH,
81
69
                                   EHOSTUNREACH, ECONNREFUSED, EPROTO,
82
 
                                   EIO, ENOENT, ENXIO, error_t,
83
 
                                   ENOMEM, EISDIR, ENOTEMPTY */
84
 
#include <stdio.h>              /* fprintf(), stderr, perror(), FILE,
85
 
                                   vfprintf(), off_t, SEEK_SET,
86
 
                                   stdout, fwrite(), ferror(),
87
 
                                   fflush(), asprintf() */
88
 
#include <stdarg.h>             /* va_list, va_start(), vfprintf() */
89
 
#include <stdlib.h>             /* realloc(), free(), malloc(),
90
 
                                   getenv(), EXIT_FAILURE, setenv(),
91
 
                                   EXIT_SUCCESS, strtof(), strtod(),
92
 
                                   srand(), mkdtemp(), abort() */
93
 
#include <string.h>             /* strdup(), strcmp(), strlen(),
94
 
                                   strerror(), strncpy(), strspn(),
95
 
                                   memcpy(), strrchr(), strchr(),
96
 
                                   strsignal() */
97
 
#include <fcntl.h>              /* open(), O_RDONLY, O_DIRECTORY,
98
 
                                   O_PATH, O_CLOEXEC, openat(),
99
 
                                   O_NOFOLLOW, AT_REMOVEDIR */
100
 
#include <iso646.h>             /* or, and, not */
101
 
#include <sys/stat.h>           /* struct stat, fstat(), fstatat(),
102
 
                                   S_ISREG(), S_IXUSR, S_IXGRP,
103
 
                                   S_IXOTH, lstat() */
104
 
#include <net/if.h>             /* IF_NAMESIZE, if_indextoname(),
105
 
                                   if_nametoindex(), SIOCGIFFLAGS,
106
 
                                   IFF_LOOPBACK, IFF_POINTOPOINT,
107
 
                                   IFF_BROADCAST, IFF_NOARP, IFF_UP,
108
 
                                   IFF_RUNNING, SIOCSIFFLAGS */
109
 
#include <sysexits.h>           /* EX_NOPERM, EX_OSERR,
110
 
                                   EX_UNAVAILABLE, EX_USAGE */
 
70
                                   EIO, ENOENT, ENXIO, ENOMEM, EISDIR,
 
71
                                   ENOTEMPTY,
 
72
                                   program_invocation_short_name */
 
73
#include <time.h>               /* nanosleep(), time(), sleep() */
 
74
#include <net/if.h>             /* ioctl, ifreq, SIOCGIFFLAGS, IFF_UP,
 
75
                                   SIOCSIFFLAGS, if_indextoname(),
 
76
                                   if_nametoindex(), IF_NAMESIZE */
 
77
#include <netinet/in.h>         /* IN6_IS_ADDR_LINKLOCAL,
 
78
                                   INET_ADDRSTRLEN, INET6_ADDRSTRLEN
 
79
                                */
 
80
#include <unistd.h>             /* close(), SEEK_SET, off_t, write(),
 
81
                                   getuid(), getgid(), seteuid(),
 
82
                                   setgid(), pause(), _exit(),
 
83
                                   unlinkat() */
 
84
#include <arpa/inet.h>          /* inet_pton(), htons() */
 
85
#include <iso646.h>             /* not, or, and */
 
86
#include <argp.h>               /* struct argp_option, error_t, struct
 
87
                                   argp_state, struct argp,
 
88
                                   argp_parse(), ARGP_KEY_ARG,
 
89
                                   ARGP_KEY_END, ARGP_ERR_UNKNOWN */
 
90
#include <signal.h>             /* sigemptyset(), sigaddset(),
 
91
                                   sigaction(), SIGTERM, sig_atomic_t,
 
92
                                   raise() */
 
93
#include <sysexits.h>           /* EX_OSERR, EX_USAGE, EX_UNAVAILABLE,
 
94
                                   EX_NOHOST, EX_IOERR, EX_PROTOCOL */
 
95
#include <sys/wait.h>           /* waitpid(), WIFEXITED(),
 
96
                                   WEXITSTATUS(), WTERMSIG() */
111
97
#include <grp.h>                /* setgroups() */
112
 
#include <sys/wait.h>           /* waitpid(), WIFEXITED(),
113
 
                                   WEXITSTATUS(), WIFSIGNALED(),
114
 
                                   WTERMSIG() */
115
 
#include <signal.h>             /* kill(), SIGTERM, struct sigaction,
116
 
                                   SIG_DFL, sigemptyset(),
117
 
                                   sigaddset(), SIGINT, SIGHUP,
118
 
                                   SIG_IGN, raise() */
119
 
#include <sys/socket.h>         /* struct sockaddr_storage, AF_INET6,
120
 
                                   PF_INET6, AF_INET, PF_INET,
121
 
                                   socket(), SOCK_STREAM,
122
 
                                   SOCK_CLOEXEC, struct sockaddr,
123
 
                                   connect(), SOCK_DGRAM */
124
 
#include <argz.h>               /* argz_next(), argz_add_sep(),
125
 
                                   argz_delete(), argz_stringify(),
126
 
                                   argz_add(), argz_count() */
127
 
#include <inttypes.h>           /* PRIuMAX, uintmax_t, uint32_t,
128
 
                                   PRIdMAX, PRIu16, intmax_t,
129
 
                                   strtoimax() */
130
 
#include <arpa/inet.h>          /* inet_pton() */
131
 
#include <stdint.h>             /* uint32_t, intptr_t, uint16_t */
 
98
#include <argz.h>               /* argz_add_sep(), argz_next(),
 
99
                                   argz_delete(), argz_append(),
 
100
                                   argz_stringify(), argz_add(),
 
101
                                   argz_count() */
132
102
#include <netdb.h>              /* getnameinfo(), NI_NUMERICHOST,
133
103
                                   EAI_SYSTEM, gai_strerror() */
134
 
#include <sys/ioctl.h>          /* ioctl() */
135
 
#include <dirent.h>             /* struct dirent, scandirat(),
136
 
                                   alphasort(), scandir() */
137
 
#include <limits.h>             /* INT_MAX */
138
104
 
139
105
#ifdef __linux__
140
106
#include <sys/klog.h>           /* klogctl() */
153
119
 
154
120
/* GnuTLS */
155
121
#include <gnutls/gnutls.h>      /* All GnuTLS types, constants and
156
 
                                   functions: gnutls_*, GNUTLS_* */
 
122
                                   functions:
 
123
                                   gnutls_*
 
124
                                   init_gnutls_session(),
 
125
                                   GNUTLS_* */
157
126
#if GNUTLS_VERSION_NUMBER < 0x030600
158
127
#include <gnutls/openpgp.h>
159
128
                         /* gnutls_certificate_set_openpgp_key_file(),
160
129
                            GNUTLS_OPENPGP_FMT_BASE64 */
161
130
#elif GNUTLS_VERSION_NUMBER >= 0x030606
162
 
#include <gnutls/x509.h>        /* GNUTLS_PKCS_PLAIN,
163
 
                                   GNUTLS_PKCS_NULL_PASSWORD */
 
131
#include <gnutls/x509.h>        /* gnutls_pkcs_encrypt_flags_t,
 
132
                                 GNUTLS_PKCS_PLAIN,
 
133
                                 GNUTLS_PKCS_NULL_PASSWORD */
164
134
#endif
165
135
 
166
136
/* GPGME */
167
137
#include <gpgme.h>              /* All GPGME types, constants and
168
138
                                   functions:
169
 
                                   gpgme_*, GPG_ERR_NO_*,
170
 
                                   GPGME_IMPORT_*
171
 
                                   GPGME_PROTOCOL_OpenPGP */
 
139
                                   gpgme_*
 
140
                                   GPGME_PROTOCOL_OpenPGP,
 
141
                                   GPG_ERR_NO_* */
172
142
 
173
143
#define BUFFER_SIZE 256
174
144
 
426
396
        fprintf_plus(stderr,
427
397
                     "Setting system clock to key file mtime");
428
398
      }
429
 
      if(clock_settime(CLOCK_REALTIME, &keystat.st_mtim) != 0){
430
 
        perror_plus("clock_settime");
 
399
      time_t keytime = keystat.st_mtim.tv_sec;
 
400
      if(stime(&keytime) != 0){
 
401
        perror_plus("stime");
431
402
      }
432
403
      ret = lower_privileges();
433
404
      if(ret != 0){
2745
2716
  }
2746
2717
  
2747
2718
  {
 
2719
    /* Work around Debian bug #633582:
 
2720
       <https://bugs.debian.org/633582> */
 
2721
    
2748
2722
    /* Re-raise privileges */
2749
2723
    ret = raise_privileges();
2750
2724
    if(ret != 0){
2753
2727
    } else {
2754
2728
      struct stat st;
2755
2729
      
2756
 
      /* Work around Debian bug #633582:
2757
 
         <https://bugs.debian.org/633582> */
2758
 
 
2759
2730
      if(strcmp(seckey, PATHDIR "/" SECKEY) == 0){
2760
2731
        int seckey_fd = open(seckey, O_RDONLY);
2761
2732
        if(seckey_fd == -1){
2820
2791
        }
2821
2792
      }
2822
2793
      
2823
 
      /* Work around Debian bug #981302
2824
 
         <https://bugs.debian.org/981302> */
2825
 
      if(lstat("/dev/fd", &st) != 0 and errno == ENOENT){
2826
 
        ret = symlink("/proc/self/fd", "/dev/fd");
2827
 
        if(ret == -1){
2828
 
          perror_plus("Failed to create /dev/fd symlink");
2829
 
        }
2830
 
      }
2831
 
 
2832
2794
      /* Lower privileges */
2833
2795
      ret = lower_privileges();
2834
2796
      if(ret != 0){