[snmp/agent] Simultaneous snmpa:backup/1,2 calls interfere

Simultaneous snmpa#backup">snmpa:backup/1,2 calls interfere.
The master agent did not check if a backup was already in
progress when a backup request was accepted

OTP-9884

5 files changed, 111 insertions, 15 deletions

diff --git a/lib/snmp/doc/src/notes.xml b/lib/snmp/doc/src/notes.xml
index 9082868e39..2b0feb6682 100644
--- a/lib/snmp/doc/src/notes.xml
+++ b/lib/snmp/doc/src/notes.xml
@@ -33,6 +33,64 @@
   </header>
 
   <section>
+    <title>SNMP Development Toolkit 4.17.4</title>
+
+    <p>Version 4.17.4 supports code replacement in runtime from/to
+      version 4.17.3, 4.17.2, 4.17.1, 4.17, 4.16.2, 4.16.1 and 4.16.</p>
+
+    <section>
+      <title>Improvements and new features</title>
+      <p>-</p>
+
+      <!--
+      <list type="bulleted">
+        <item>
+          <p>[agent] DoS attack using GET-BULK with large value of 
+	  MaxRepetitions.
+	  A preventive method has been implementing by simply 
+	  limit the number of varbinds that can be included in 
+	  a Get-BULK response message. This is specified by the 
+	  new config option, 
+	  <seealso marker="snmp_app#agent_gb_max_vbs">gb_max_vbs</seealso>. 
+	  </p>
+	  <p>Own Id: OTP-9700</p>
+        </item>
+
+      </list>
+      -->
+
+    </section>
+
+    <section>
+      <title>Reported Fixed Bugs and Malfunctions</title>
+      <!--
+      <p>-</p>
+      -->
+
+      <list type="bulleted">
+        <item>
+          <p>[agent] Simultaneous 
+	  <seealso marker="snmpa#backup">snmpa:backup/1,2</seealso> 
+	  calls can interfere.
+	  The master agent did not check if a backup was already in 
+	  progress when a backup request was accepted. </p>
+          <p>Own Id: OTP-9884</p>
+          <p>Aux Id: Seq 11995</p>
+        </item>
+
+      </list>
+
+    </section>
+
+    <section>
+      <title>Incompatibilities</title>
+      <p>-</p>
+    </section>
+
+  </section> <!-- 4.17.4 -->
+
+
+  <section>
     <title>SNMP Development Toolkit 4.17.3</title>
 
     <p>Version 4.17.3 supports code replacement in runtime from/to
diff --git a/lib/snmp/doc/src/snmpa.xml b/lib/snmp/doc/src/snmpa.xml
index 1be6abe6dd..3bc2063f4e 100644
--- a/lib/snmp/doc/src/snmpa.xml
+++ b/lib/snmp/doc/src/snmpa.xml
@@ -1,10 +1,10 @@
-<?xml version="1.0" encoding="latin1" ?>
+<?xml version="1.0" encoding="iso-8859-1" ?>
 <!DOCTYPE erlref SYSTEM "erlref.dtd">
 
 <erlref>
   <header>
     <copyright>
-      <year>2004</year><year>2010</year>
+      <year>2004</year><year>2012</year>
       <holder>Ericsson AB. All Rights Reserved.</holder>
     </copyright>
     <legalnotice>
@@ -198,12 +198,18 @@ notification_delivery_info() = #snmpa_notification_delivery_info{}
       <type>
         <v>BackupDir = string()</v>
         <v>Agent = pid() | atom()</v>
+        <v>Reason = backup_in_progress | term()</v>
       </type>
       <desc>
         <p>Backup persistent/permanent data handled by the agent
           (such as local-db, mib-data and vacm). </p>
         <p>Data stored by mnesia is not handled. </p>
         <p>BackupDir cannot be identical to DbDir. </p>
+        <p>Simultaneous backup calls are <em>not</em> allowed. 
+	That is, two different processes cannot simultaneously 
+	successfully call this function. One of them will be first, 
+	and succeed. The second will fail with the error reason
+	<c>backup_in_progress</c>. </p>
 
         <marker id="info"></marker>
       </desc>
@@ -217,13 +223,13 @@ notification_delivery_info() = #snmpa_notification_delivery_info{}
       </type>
       <desc>
         <p>Returns a list (a dictionary) containing information about
-          the agent. Information includes loaded MIBs, registered
-          sub-agents, some information about the memory allocation. </p>
-        <p>As of version 4.4 the format of the info has been changed. 
-          To convert the info to the old format, call the 
-          <seealso marker="#old_info_format">old_info_format</seealso> 
-          function. </p>
-
+	the agent. Information includes loaded MIBs, registered
+	sub-agents, some information about the memory allocation. </p>
+	<p>As of version 4.4 the format of the info has been changed. 
+	To convert the info to the old format, call the 
+	<seealso marker="#old_info_format">old_info_format</seealso> 
+	function. </p>
+	
         <marker id="old_info_format"></marker>
       </desc>
     </func>
diff --git a/lib/snmp/src/agent/snmpa_agent.erl b/lib/snmp/src/agent/snmpa_agent.erl
index 00fe9be098..e3178aacc6 100644
--- a/lib/snmp/src/agent/snmpa_agent.erl
+++ b/lib/snmp/src/agent/snmpa_agent.erl
@@ -1,7 +1,7 @@
 %%
 %% %CopyrightBegin%
 %%
-%% Copyright Ericsson AB 1996-2010. All Rights Reserved.
+%% Copyright Ericsson AB 1996-2012. All Rights Reserved.
 %%
 %% The contents of this file are subject to the Erlang Public License,
 %% Version 1.1, (the "License"); you may not use this file except in
@@ -1190,7 +1190,8 @@ handle_call(info, _From, S) ->
 handle_call(get_net_if, _From, S) ->
     {reply, get(net_if), S};
 
-handle_call({backup, BackupDir}, From, S) ->
+%% Only accept a backup request if there is none already in progress
+handle_call({backup, BackupDir}, From, #state{backup = undefined} = S) ->
     ?vlog("backup: ~p", [BackupDir]),
     Pid = self(),
     V   = get(verbosity),
@@ -1207,7 +1208,11 @@ handle_call({backup, BackupDir}, From, S) ->
 	  end),
     ?vtrace("backup server: ~p", [BackupServer]),
     {noreply, S#state{backup = {BackupServer, From}}};
-    
+
+handle_call({backup, _BackupDir}, From, #state{backup = Backup} = S) ->
+    ?vinfo("backup already in progress: ~p", [Backup]),
+    {reply, {error, backup_in_progress}, S};
+
 handle_call(dump_mibs, _From, S) ->
     Reply = snmpa_mib:dump(get(mibserver)),
     {reply, Reply, S};
diff --git a/lib/snmp/src/agent/snmpa_mib.erl b/lib/snmp/src/agent/snmpa_mib.erl
index ce90db18b3..574467d38f 100644
--- a/lib/snmp/src/agent/snmpa_mib.erl
+++ b/lib/snmp/src/agent/snmpa_mib.erl
@@ -1,7 +1,7 @@
 %%
 %% %CopyrightBegin%
 %%
-%% Copyright Ericsson AB 1996-2010. All Rights Reserved.
+%% Copyright Ericsson AB 1996-2012. All Rights Reserved.
 %%
 %% The contents of this file are subject to the Erlang Public License,
 %% Version 1.1, (the "License"); you may not use this file except in
@@ -552,8 +552,12 @@ handle_call({dump, File}, _From, #state{data = Data} = State) ->
     Reply = snmpa_mib_data:dump(Data, File),
     {reply, Reply, State};
     
-handle_call({backup, BackupDir}, From, #state{data = Data} = State) ->
-    ?vlog("backup to ~s",[BackupDir]),
+%% This check (that there is no backup already in progress) is also 
+%% done in the master agent process, but just in case a user issues 
+%% a backup call to this process directly, we add a similar check here. 
+handle_call({backup, BackupDir}, From, 
+	    #state{backup = undefined, data = Data} = State) ->
+    ?vlog("backup to ~s", [BackupDir]),
     Pid = self(),
     V   = get(verbosity),
     case file:read_file_info(BackupDir) of
@@ -576,6 +580,10 @@ handle_call({backup, BackupDir}, From, #state{data = Data} = State) ->
 	    {reply, Error, State}
     end;
     
+handle_call({backup, _BackupDir}, From, #state{backup = Backup} = S) ->
+    ?vinfo("backup already in progress: ~p", [Backup]),
+    {reply, {error, backup_in_progress}, S};
+
 handle_call(stop, _From, State) ->
     ?vlog("stop",[]),    
     {stop, normal, ok, State};
diff --git a/lib/snmp/src/app/snmp.appup.src b/lib/snmp/src/app/snmp.appup.src
index 4ac6daf579..6655935c5c 100644
--- a/lib/snmp/src/app/snmp.appup.src
+++ b/lib/snmp/src/app/snmp.appup.src
@@ -22,6 +22,12 @@
 %% ----- U p g r a d e -------------------------------------------------------
 
  [
+  {"4.17.3",
+   [
+    {update, snmpa_mib,   soft, soft_purge, soft_purge, []}, 
+    {update, snmpa_agent, soft, soft_purge, soft_purge, []}
+   ]
+  },
   {"4.17.2",
    [
     {load_module, snmpa, soft_purge, soft_purge, []}, 
@@ -41,6 +47,7 @@
     {load_module, snmpa_trap, soft_purge, soft_purge, []}, 
     {load_module, snmpa_vacm, soft_purge, soft_purge, []}, 
     {update,      snmpa_supervisor, soft, soft_purge, soft_purge, []}, 
+    {update,      snmpa_mib,   soft, soft_purge, soft_purge, []}, 
     {update,      snmpa_agent, soft, soft_purge, soft_purge, []}, 
     {load_module, snmpm, soft_purge, soft_purge, [snmpm_server]},
     {update,      snmpm_server, soft, soft_purge, soft_purge, []}
@@ -57,6 +64,7 @@
     {load_module, snmpm, soft_purge, soft_purge, [snmpm_server]},
     {update,      snmpm_server, soft, soft_purge, soft_purge, []}, 
     {update,      snmpa_supervisor, soft, soft_purge, soft_purge, []}, 
+    {update,      snmpa_mib,   soft, soft_purge, soft_purge, []}, 
     {update,      snmpa_agent, soft, soft_purge, soft_purge, []}
    ]
   }, 
@@ -72,6 +80,7 @@
     {load_module, snmpa_mpd, soft_purge, soft_purge, [snmpa_usm]},
     {load_module, snmpa_usm, soft_purge, soft_purge, []},
     {update,      snmpa_supervisor, soft, soft_purge, soft_purge, []}, 
+    {update,      snmpa_mib,   soft, soft_purge, soft_purge, []}, 
     {update,      snmpa_agent, soft, soft_purge, soft_purge, []},
     {load_module, snmpa_net_if, soft_purge, soft_purge, []},
 
@@ -135,6 +144,12 @@
 %% ------D o w n g r a d e ---------------------------------------------------
 
  [
+  {"4.17.3",
+   [
+    {update, snmpa_mib,   soft, soft_purge, soft_purge, []}, 
+    {update, snmpa_agent, soft, soft_purge, soft_purge, []}
+   ]
+  },
   {"4.17.2",
    [
     {load_module, snmpa, soft_purge, soft_purge, []}, 
@@ -143,6 +158,7 @@
     {load_module, snmpa_trap, soft_purge, soft_purge, []}, 
     {load_module, snmpa_vacm, soft_purge, soft_purge, []}, 
     {update,      snmpa_supervisor, soft, soft_purge, soft_purge, []}, 
+    {update,      snmpa_mib,   soft, soft_purge, soft_purge, []}, 
     {update,      snmpa_agent, soft, soft_purge, soft_purge, []}
    ]
   },
@@ -154,6 +170,7 @@
     {load_module, snmpa_trap, soft_purge, soft_purge, []}, 
     {load_module, snmpa_vacm, soft_purge, soft_purge, []}, 
     {update,      snmpa_supervisor, soft, soft_purge, soft_purge, []}, 
+    {update,      snmpa_mib,   soft, soft_purge, soft_purge, []}, 
     {update,      snmpa_agent, soft, soft_purge, soft_purge, []}, 
     {load_module, snmpm, soft_purge, soft_purge, [snmpm_server]},
     {update,      snmpm_server, soft, soft_purge, soft_purge, []}
@@ -167,6 +184,7 @@
     {load_module, snmpa_trap, soft_purge, soft_purge, []}, 
     {load_module, snmpa_vacm, soft_purge, soft_purge, []}, 
     {update,      snmpa_supervisor, soft, soft_purge, soft_purge, []}, 
+    {update,      snmpa_mib,   soft, soft_purge, soft_purge, []}, 
     {update,      snmpa_agent, soft, soft_purge, soft_purge, []}, 
     {load_module, snmpa_net_if, soft_purge, soft_purge, []}, 
     {load_module, snmpm, soft_purge, soft_purge, [snmpm_server]},
@@ -186,6 +204,7 @@
     {load_module, snmpa_mpd, soft_purge, soft_purge, [snmpa_usm]},
     {load_module, snmpa_usm, soft_purge, soft_purge, []},
     {update,      snmpa_supervisor, soft, soft_purge, soft_purge, []}, 
+    {update,      snmpa_mib,   soft, soft_purge, soft_purge, []}, 
     {update,      snmpa_agent, soft, soft_purge, soft_purge, []},
     {load_module, snmpa_net_if, soft_purge, soft_purge, []},