src/patches/dnsmasq/0057-Tweak-DNSSEC-timestamp-code-to-create-file-later-rem.patch

   1 From 360f2513ab12a9bf1e262d388dd2ea8a566590a3 Mon Sep 17 00:00:00 2001
   2 From: Simon Kelley <simon@thekelleys.org.uk>
   3 Date: Sat, 7 Mar 2015 18:28:06 +0000
   4 Subject: [PATCH 57/98] Tweak DNSSEC timestamp code to create file later,
   5  removing need to chown it.
   6
   7 ---
   8  man/dnsmasq.8 |  3 ++-
   9  src/dnsmasq.c | 35 ++++++++++++++++++++++-------------
  10  src/dnsmasq.h |  3 ++-
  11  src/dnssec.c  | 18 ++++++++++--------
  12  4 files changed, 36 insertions(+), 23 deletions(-)
  13
  14 diff --git a/man/dnsmasq.8 b/man/dnsmasq.8
  15 index 097e7d75145c..2db780d90987 100644
  16 --- a/man/dnsmasq.8
  17 +++ b/man/dnsmasq.8
  18 @@ -678,7 +678,8 @@ which have not been throughly checked.
  19  Enables an alternative way of checking the validity of the system time for DNSSEC (see --dnssec-no-timecheck). In this case, the
  20  system time is considered to be valid once it becomes later than the timestamp on the specified file. The file is created and
  21  its timestamp set automatically by dnsmasq. The file must be stored on a persistent filesystem, so that it and its mtime are carried
  22 -over system restarts.
  23 +over system restarts. The timestamp file is created after dnsmasq has dropped root, so it must be in a location writable by the
  24 +unprivileged user that dnsmasq runs as.
  25  .TP
  26  .B --proxy-dnssec
  27  Copy the DNSSEC Authenticated Data bit from upstream servers to downstream clients and cache it.  This is an
  28 diff --git a/src/dnsmasq.c b/src/dnsmasq.c
  29 index 9e05c0e31569..f3e5bcffec4f 100644
  30 --- a/src/dnsmasq.c
  31 +++ b/src/dnsmasq.c
  32 @@ -58,9 +58,6 @@ int main (int argc, char **argv)
  33    struct dhcp_context *context;
  34    struct dhcp_relay *relay;
  35  #endif
  36 -#ifdef HAVE_DNSSEC
  37 -  int badtime;
  38 -#endif
  39
  40  #ifdef LOCALEDIR
  41    setlocale(LC_ALL, "");
  42 @@ -156,10 +153,10 @@ int main (int argc, char **argv)
  43      {
  44  #ifdef HAVE_DNSSEC
  45        if (!daemon->ds)
  46 -       die(_("No trust anchors provided for DNSSEC"), NULL, EC_BADCONF);
  47 +       die(_("no trust anchors provided for DNSSEC"), NULL, EC_BADCONF);
  48
  49        if (daemon->cachesize < CACHESIZ)
  50 -       die(_("Cannot reduce cache size from default when DNSSEC enabled"), NULL, EC_BADCONF);
  51 +       die(_("cannot reduce cache size from default when DNSSEC enabled"), NULL, EC_BADCONF);
  52  #else
  53        die(_("DNSSEC not available: set HAVE_DNSSEC in src/config.h"), NULL, EC_BADCONF);
  54  #endif
  55 @@ -172,10 +169,10 @@ int main (int argc, char **argv)
  56
  57  #ifdef HAVE_CONNTRACK
  58    if (option_bool(OPT_CONNTRACK) && (daemon->query_port != 0 || daemon->osport))
  59 -    die (_("Cannot use --conntrack AND --query-port"), NULL, EC_BADCONF);
  60 +    die (_("cannot use --conntrack AND --query-port"), NULL, EC_BADCONF);
  61  #else
  62    if (option_bool(OPT_CONNTRACK))
  63 -    die(_("Conntrack support not available: set HAVE_CONNTRACK in src/config.h"), NULL, EC_BADCONF);
  64 +    die(_("conntrack support not available: set HAVE_CONNTRACK in src/config.h"), NULL, EC_BADCONF);
  65  #endif
  66
  67  #ifdef HAVE_SOLARIS_NETWORK
  68 @@ -195,7 +192,7 @@ int main (int argc, char **argv)
  69
  70  #ifndef HAVE_LOOP
  71    if (option_bool(OPT_LOOP_DETECT))
  72 -    die(_("Loop detection not available: set HAVE_LOOP in src/config.h"), NULL, EC_BADCONF);
  73 +    die(_("loop detection not available: set HAVE_LOOP in src/config.h"), NULL, EC_BADCONF);
  74  #endif
  75
  76    now = dnsmasq_time();
  77 @@ -373,10 +370,6 @@ int main (int argc, char **argv)
  78    if (baduser)
  79      die(_("unknown user or group: %s"), baduser, EC_BADCONF);
  80
  81 -#ifdef HAVE_DNSSEC
  82 -  badtime = setup_timestamp(ent_pw);
  83 -#endif
  84 -
  85    /* implement group defaults, "dip" if available, or group associated with uid */
  86    if (!daemon->group_set && !gp)
  87      {
  88 @@ -693,10 +686,23 @@ int main (int argc, char **argv)
  89  #ifdef HAVE_DNSSEC
  90    if (option_bool(OPT_DNSSEC_VALID))
  91      {
  92 +      int rc;
  93 +
  94 +      /* Delay creating the timestamp file until here, after we've changed user, so that
  95 +        it has the correct owner to allow updating the mtime later.
  96 +        This means we have to report fatal errors via the pipe. */
  97 +      if ((rc = setup_timestamp()) == -1)
  98 +       {
  99 +         send_event(err_pipe[1], EVENT_TIME_ERR, errno, daemon->timestamp_file);
 100 +         _exit(0);
 101 +       }
 102 +
 103        my_syslog(LOG_INFO, _("DNSSEC validation enabled"));
 104 +
 105        if (option_bool(OPT_DNSSEC_TIME))
 106         my_syslog(LOG_INFO, _("DNSSEC signature timestamps not checked until first cache reload"));
 107 -      if (badtime)
 108 +
 109 +      if (rc == 1)
 110         my_syslog(LOG_INFO, _("DNSSEC signature timestamps not checked until system time valid"));
 111      }
 112  #endif
 113 @@ -1170,6 +1176,9 @@ static void fatal_event(struct event_desc *ev, char *msg)
 114
 115      case EVENT_TFTP_ERR:
 116        die(_("TFTP directory %s inaccessible: %s"), msg, EC_FILE);
 117 +
 118 +    case EVENT_TIME_ERR:
 119 +      die(_("cannot create timestamp file %s: %s" ), msg, EC_BADCONF);
 120      }
 121  }
 122
 123 diff --git a/src/dnsmasq.h b/src/dnsmasq.h
 124 index a451cb4dd03c..fc7259881358 100644
 125 --- a/src/dnsmasq.h
 126 +++ b/src/dnsmasq.h
 127 @@ -167,6 +167,7 @@ struct event_desc {
 128  #define EVENT_INIT      21
 129  #define EVENT_NEWADDR   22
 130  #define EVENT_NEWROUTE  23
 131 +#define EVENT_TIME_ERR  24
 132
 133  /* Exit codes. */
 134  #define EC_GOOD        0
 135 @@ -1152,7 +1153,7 @@ int dnssec_chase_cname(time_t now, struct dns_header *header, size_t plen, char
 136  int dnskey_keytag(int alg, int flags, unsigned char *rdata, int rdlen);
 137  size_t filter_rrsigs(struct dns_header *header, size_t plen);
 138  unsigned char* hash_questions(struct dns_header *header, size_t plen, char *name);
 139 -int setup_timestamp(struct passwd *ent_pw);
 140 +int setup_timestamp(void);
 141
 142  /* util.c */
 143  void rand_init(void);
 144 diff --git a/src/dnssec.c b/src/dnssec.c
 145 index c60eacf73c6b..ad0d6f072ba2 100644
 146 --- a/src/dnssec.c
 147 +++ b/src/dnssec.c
 148 @@ -397,18 +397,21 @@ static int serial_compare_32(unsigned long s1, unsigned long s2)
 149
 150  /* Called at startup. If the timestamp file is configured and exists, put its mtime on
 151     timestamp_time. If it doesn't exist, create it, and set the mtime to 1-1-2015.
 152 -   Change the ownership to the user we'll be running as, so that we can update the mtime.
 153 +   return -1 -> Cannot create file.
 154 +           0 -> not using timestamp, or timestamp exists and is in past.
 155 +           1 -> timestamp exists and is in future.
 156  */
 157 +
 158  static time_t timestamp_time;
 159  static int back_to_the_future;
 160
 161 -int setup_timestamp(struct passwd *ent_pw)
 162 +int setup_timestamp(void)
 163  {
 164    struct stat statbuf;
 165
 166    back_to_the_future = 0;
 167
 168 -  if (!option_bool(OPT_DNSSEC_VALID) || !daemon->timestamp_file)
 169 +  if (!daemon->timestamp_file)
 170      return 0;
 171
 172    if (stat(daemon->timestamp_file, &statbuf) != -1)
 173 @@ -428,7 +431,8 @@ int setup_timestamp(struct passwd *ent_pw)
 174
 175    if (errno == ENOENT)
 176      {
 177 -      int fd = open(daemon->timestamp_file, O_WRONLY | O_CREAT | O_NONBLOCK, 0666);
 178 +      /* NB. for explanation of O_EXCL flag, see comment on pidfile in dnsmasq.c */
 179 +      int fd = open(daemon->timestamp_file, O_WRONLY | O_CREAT | O_NONBLOCK | O_EXCL, 0666);
 180        if (fd != -1)
 181         {
 182           struct utimbuf timbuf;
 183 @@ -436,14 +440,12 @@ int setup_timestamp(struct passwd *ent_pw)
 184           close(fd);
 185
 186           timestamp_time = timbuf.actime = timbuf.modtime = 1420070400; /* 1-1-2015 */
 187 -         if (utime(daemon->timestamp_file, &timbuf) == 0 &&
 188 -             (!ent_pw || getuid() != 0 || chown(daemon->timestamp_file, ent_pw->pw_uid, -1) == 0))
 189 +         if (utime(daemon->timestamp_file, &timbuf) == 0)
 190             goto check_and_exit;
 191         }
 192      }
 193
 194 -  die(_("Cannot create timestamp file %s: %s" ), daemon->timestamp_file, EC_BADCONF);
 195 -  return 0;
 196 +  return -1;
 197  }
 198
 199  /* Check whether today/now is between date_start and date_end */
 200 --
 201 2.1.0
 202