Modify the inotify implementation so that inotify watches are

only created after dnsmasq has changed permissions and userid.
This means that the permissions used when creating the watches
are the same as used for accessing watched files, which makes
more sense and avoids odd and confusing error conditions.

CHANGELOG

@@ -28,6 +28,12 @@ version 2.93
 	relay is in use. Many thanks to Jørgen Søvik for help
 	finding this bug.
 	
+	Modify the inotify implementation so that inotify watches are
+	only created after dnsmasq has changed permissions and userid.
+	This means that the permissions used when creating the watches
+	are the same as used for accessing watched files, which makes
+	more sense and avoids odd and confusing error conditions.
+
 	
 version 2.92
         Redesign the interaction between DNSSEC validation and per-domain

src/auth.c

@@ -591,7 +591,7 @@ size_t answer_auth(struct dns_header *header, char *limit, size_t qlen, time_t n
   if (auth && zone)
     {
       char *authname;
-      int newoffset, offset = 0;
+      int newoffset = ansp - (unsigned char *)header, offset = 0;
 
       if (!subnet)
 	authname = zone->domain;
@@ -631,8 +631,7 @@ size_t answer_auth(struct dns_header *header, char *limit, size_t qlen, time_t n
 	}
       
       /* handle NS and SOA in auth section or for explicit queries */
-       newoffset = ansp - (unsigned char *)header;
-       if (((anscount == 0 && !ns) || soa) &&
+      if (((anscount == 0 && !ns) || soa) &&
 	  add_resource_record(header, limit, &trunc, 0, &ansp, 
 			      daemon->auth_ttl, NULL, T_SOA, C_IN, "ddlllll",
 			      authname, daemon->authserver,  daemon->hostmaster,
@@ -650,11 +649,10 @@ size_t answer_auth(struct dns_header *header, char *limit, size_t qlen, time_t n
       if (anscount != 0 || ns)
 	{
 	  struct name_list *secondary;
-	  
+	 	  
 	  /* Only include the machine running dnsmasq if it's acting as an auth server */
 	  if (daemon->authinterface)
 	    {
-	      newoffset = ansp - (unsigned char *)header;
 	      if (add_resource_record(header, limit, &trunc, -offset, &ansp, 
 				      daemon->auth_ttl, NULL, T_NS, C_IN, "d", offset == 0 ? authname : NULL, daemon->authserver))
 		{
@@ -669,9 +667,11 @@ size_t answer_auth(struct dns_header *header, char *limit, size_t qlen, time_t n
 
 	  if (!subnet)
 	    for (secondary = daemon->secondary_forward_server; secondary; secondary = secondary->next)
-	      if (add_resource_record(header, limit, &trunc, offset, &ansp, 
-				      daemon->auth_ttl, NULL, T_NS, C_IN, "d", secondary->name))
+	      if (add_resource_record(header, limit, &trunc, -offset, &ansp, 
+				      daemon->auth_ttl, NULL, T_NS, C_IN, "d", offset == 0 ? authname : NULL, secondary->name))
 		{
+		  if (offset == 0) 
+		    offset = newoffset;
 		  if (ns) 
 		    anscount++;
 		  else

src/cache.c

@@ -1600,7 +1600,7 @@ void cache_reload(void)
   
 #ifdef HAVE_DNSSEC
   for (ds = daemon->ds; ds; ds = ds->next)
-    if ((cache = get_config_crec()))
+    if (ds->name && (cache = get_config_crec()))
       {
 	
 	if (!(cache->addr.ds.keydata = blockdata_alloc(ds->digest, ds->digestlen)))

src/dnsmasq.c

@@ -437,14 +437,6 @@ int main (int argc, char **argv)
 	daemon->tcp_pipes[i] = -1;
     }
 
-#ifdef HAVE_INOTIFY
-  if ((daemon->port != 0 && !option_bool(OPT_NO_RESOLV)) ||
-      daemon->dynamic_dirs)
-    inotify_dnsmasq_init();
-  else
-    daemon->inotifyfd = -1;
-#endif
-
   if (daemon->dump_file)
 #ifdef HAVE_DUMPFILE
     dump_init();
@@ -864,6 +856,14 @@ int main (int argc, char **argv)
     }
 #endif
 
+#ifdef HAVE_INOTIFY
+  if ((daemon->port != 0 && !option_bool(OPT_NO_RESOLV)) ||
+      daemon->dynamic_dirs)
+    inotify_dnsmasq_init(err_pipe[1]);
+  else
+    daemon->inotifyfd = -1;
+#endif
+  
    /* Don't start logging malloc before logging is set up. */
   daemon->log_malloc = option_bool(OPT_LOG_MALLOC);
   
@@ -946,9 +946,27 @@ int main (int argc, char **argv)
 	my_syslog(LOG_INFO, _("DNSSEC signature timestamps not checked until system time valid"));
 
       for (ds = daemon->ds; ds; ds = ds->next)
-	my_syslog(LOG_INFO,
-		  ds->digestlen == 0 ? _("configured with negative trust anchor for %s") : _("configured with trust anchor for %s keytag %u"),
-		  ds->name[0] == 0 ? "<root>" : ds->name, ds->keytag);
+	{
+	  struct ds_config *ds1;
+	  
+	  for (ds1 = ds->next; ds1; ds1 = ds1->next)
+	    if (strcmp(ds->name, ds1->name) == 0 &&
+		ds->digestlen == ds1->digestlen &&
+		(ds->digestlen == 0 ||
+		 (ds->algo == ds1->algo &&
+		  ds->keytag == ds1->keytag &&
+		  ds->digest_type == ds1->digest_type &&
+		  memcmp(ds->digest, ds1->digest, ds->digestlen) == 0)))
+	      {
+		ds->name = NULL; /* Mark as duplicate */
+		break;
+	      }
+	  
+	  if (ds->name)
+	    my_syslog(LOG_INFO,
+		      ds->digestlen == 0 ? _("configured with negative trust anchor for %s") : _("configured with trust anchor for %s keytag %u"),
+		      ds->name[0] == 0 ? "<root>" : ds->name, ds->keytag);
+	}
     }
 #endif
 
@@ -1527,6 +1545,26 @@ static void fatal_event(struct event_desc *ev, char *msg)
       /* fall through */
     case EVENT_TIME_ERR:
       die(_("cannot create timestamp file %s: %s" ), msg, EC_BADCONF);
+
+      /* fall through */
+    case EVENT_LINK_ERR:
+      die(_("cannot access path %s: %s" ), msg, EC_MISC);
+
+       /* fall through */
+    case EVENT_INOTFY_ERR:
+      die(_("failed to create inotify: %s" ), NULL, EC_MISC);
+
+      /* fall through */
+    case EVENT_TMSL_ERR:
+      die(_("too many symlinks following %s"), msg, EC_MISC);
+
+      /* fall through */
+    case EVENT_RESOLV_ERR:
+      die(_("directory %s for resolv-file is missing, cannot poll"), msg, EC_MISC);
+
+      /* fall through */
+    case EVENT_IFILE_ERR:
+      die(_("failed to create inotify for %s: %s"), msg, EC_MISC);
     }
 }	
       

src/dnsmasq.h

@@ -201,6 +201,11 @@ struct event_desc {
 #define EVENT_TIME_ERR   24
 #define EVENT_SCRIPT_LOG 25
 #define EVENT_TIME       26
+#define EVENT_LINK_ERR   27
+#define EVENT_INOTFY_ERR 28
+#define EVENT_TMSL_ERR   29
+#define EVENT_RESOLV_ERR 30
+#define EVENT_IFILE_ERR  31
 
 /* Exit codes. */
 #define EC_GOOD        0
@@ -1497,11 +1502,13 @@ unsigned char *do_rfc1035_name(unsigned char *p, char *sval, char *limit);
 void *safe_malloc(size_t size);
 void safe_strncpy(char *dest, const char *src, size_t size);
 void safe_pipe(int *fd, int read_noblock);
+#define malloc_log(x, y) malloc_log_real(__func__, __LINE__, (x), (y))
 #define whine_malloc(x) whine_malloc_real(__func__, __LINE__, (x))
 #define whine_realloc(x, y) whine_realloc_real(NULL, __func__, __LINE__, (x), (y))
 #define expand_buf(x, y) expand_buf_real(__func__, __LINE__, (x), (y))
 #define expand_workspace(x, y, z) expand_workspace_real(__func__, __LINE__, (x), (y), (z))
 #define free(x) free_real(__func__, __LINE__, (x))
+void malloc_log_real(const char *func, unsigned int line, void *mem, size_t size);
 void free_real(const char *func, unsigned int line, void *ptr);
 void *whine_malloc_real(const char *func, unsigned int line, size_t size);
 void *whine_realloc_real(const char *wrapper, const char *func, unsigned int line, void *ptr, size_t size);
@@ -1905,7 +1912,7 @@ int detect_loop(char *query, int type);
 
 /* inotify.c */
 #ifdef HAVE_INOTIFY
-void inotify_dnsmasq_init(void);
+void inotify_dnsmasq_init(int errfd);
 int inotify_check(time_t now);
 void set_dynamic_inotify(int flag, int total_size, struct crec **rhash, int revhashsz);
 #endif

src/inotify.c

@@ -40,7 +40,7 @@ static char *inotify_buffer;
    points to, made absolute if relative.
    If path doesn't exist or is not a symlink, return NULL.
    Return value is malloc'ed */
-static char *my_readlink(char *path)
+static char *my_readlink(int errfd, char *path)
 {
   ssize_t rc, size = 64;
   char *buf;
@@ -59,7 +59,10 @@ static char *my_readlink(char *path)
 	      return NULL;
 	    }
 	  else
-	    die(_("cannot access path %s: %s"), path, EC_MISC);
+	    {
+	      send_event(errfd, EVENT_LINK_ERR, errno, path);
+	      _exit(0);
+	    }
 	}
       else if (rc < size-1)
 	{
@@ -85,15 +88,18 @@ static char *my_readlink(char *path)
     }
 }
 
-void inotify_dnsmasq_init()
+void inotify_dnsmasq_init(int errfd)
 {
   struct resolvc *res;
   inotify_buffer = safe_malloc(INOTIFY_SZ);
   daemon->inotifyfd = inotify_init1(IN_NONBLOCK | IN_CLOEXEC);
   
   if (daemon->inotifyfd == -1)
-    die(_("failed to create inotify: %s"), NULL, EC_MISC);
-
+    {
+      send_event(errfd, EVENT_INOTFY_ERR, errno, NULL);
+      _exit(0);
+    }
+  
   if (daemon->port == 0 || option_bool(OPT_NO_RESOLV))
     return;
   
@@ -105,10 +111,13 @@ void inotify_dnsmasq_init()
       strcpy(path, res->name);
 
       /* Follow symlinks until we reach a non-symlink, or a non-existent file. */
-      while ((new_path = my_readlink(path)))
+      while ((new_path = my_readlink(errfd, path)))
 	{
 	  if (links-- == 0)
-	    die(_("too many symlinks following %s"), res->name, EC_MISC);
+	    {
+	      send_event(errfd, EVENT_TMSL_ERR, 0, res->name);
+	      _exit(0);
+	    }
 	  free(path);
 	  path = new_path;
 	}
@@ -124,12 +133,18 @@ void inotify_dnsmasq_init()
 	  *d = '/';
 	  
 	  if (res->wd == -1 && errno == ENOENT)
-	    die(_("directory %s for resolv-file is missing, cannot poll"), res->name, EC_MISC);
+	    {
+	      send_event(errfd, EVENT_RESOLV_ERR, 0, res->name);
+	      _exit(0);
+	    }
 	}	  
 	 
       if (res->wd == -1)
-	die(_("failed to create inotify for %s: %s"), res->name, EC_MISC);
-	
+	{
+	  send_event(errfd, EVENT_IFILE_ERR, errno, res->name);
+	  _exit(0);
+	}
+      	
     }
 }
 

src/rfc1035.c

@@ -1427,6 +1427,11 @@ int check_for_ignored_address(struct dns_header *header, size_t qlen)
   return check_bad_address(header, qlen, daemon->ignore_addr, NULL, NULL);
 }
 
+/* Nameoffset > 0 means that the name of the new record already exists at the given offset,
+   so use a "jump" to that.
+   Nameoffset == 0 means use the first variable argument as the name of the new record.
+   nameoffset < 0 means use the first variable argument as the start of the new record name,
+   then "jump" to -nameoffset to complete it. */
 int add_resource_record(struct dns_header *header, char *limit, int *truncp, int nameoffset, unsigned char **pp, 
 			unsigned long ttl, int *offset, unsigned short type, unsigned short class, char *format, ...)
 {

src/util.c

@@ -266,6 +266,10 @@ char *canonicalise(char *in, int *nomem)
 	  
 	  return NULL;
 	}
+
+      /* IDN library doesnt call our malloc wrapper, so log this by steam */
+      if (ret)
+	malloc_log(ret, strlen(ret)+1);
       
       return ret;
     }
@@ -323,13 +327,15 @@ void *safe_malloc(size_t size)
 }
 
 /* Ensure limited size string is always terminated.
- * Can be replaced by (void)strlcpy() on some platforms */
+   Can be replaced by (void)strlcpy() on some platforms.
+   src may be NULL in which case we return an empty string. */
 void safe_strncpy(char *dest, const char *src, size_t size)
 {
   if (size != 0)
     {
-      dest[size-1] = '\0';
-      strncpy(dest, src, size-1);
+      dest[0] = dest[size-1] = '\0';
+      if (src)
+	strncpy(dest, src, size-1);
     }
 }
 
@@ -993,6 +999,12 @@ int expand_workspace_real(const char *func, unsigned int line, unsigned char ***
   return 1;
 }
 
+void malloc_log_real(const char *func, unsigned int line, void *mem, size_t size)
+{
+  if (mem && daemon->log_malloc)
+    my_syslog(LOG_INFO, _("malloc: %s:%u %zu bytes at %x"), func, line, size, hash_ptr(mem));
+}
+
 #undef free
 void free_real(const char *func, unsigned int line, void *ptr)
 {