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| author | Rainer Gerhards <rgerhards@adiscon.com> | 2005-09-23 10:36:21 +0000 |
|---|---|---|
| committer | Rainer Gerhards <rgerhards@adiscon.com> | 2005-09-23 10:36:21 +0000 |
| commit | 8f0c0ae6d2f605df5b2598af4db4a20ed0eef30b (patch) | |
| tree | bed45c20cf88775c3fd5c575dea98d7338bd79a6 | |
| parent | 303642578686951cd4af4433a9ddecffcca60aff (diff) | |
| download | rsyslog-8f0c0ae6d2f605df5b2598af4db4a20ed0eef30b.tar.gz rsyslog-8f0c0ae6d2f605df5b2598af4db4a20ed0eef30b.tar.xz rsyslog-8f0c0ae6d2f605df5b2598af4db4a20ed0eef30b.zip | |
updated doc for new MySQL escaping
| -rw-r--r-- | doc/rsyslog_conf.html | 58 |
1 files changed, 52 insertions, 6 deletions
diff --git a/doc/rsyslog_conf.html b/doc/rsyslog_conf.html index ddcec041..30dd025f 100644 --- a/doc/rsyslog_conf.html +++ b/doc/rsyslog_conf.html @@ -3,7 +3,7 @@ <title>rsyslog.conf file</title>
</head>
<body>
-<h1>rsyslog.conf configuration file</h1>
+<h1>sqrsyslog.conf configuration file</h1>
<p><b>This document is currently being enhanced. Please pardon its current
appearance.</b></p>
<p><b>Rsyslogd is configured via the rsyslog.conf file</b>, typically found in
@@ -55,10 +55,23 @@ options - the later ones are processed by the property replacer and apply to a SINGLE property, only (and not the whole template).<br>
<br>
Template options are case-insensitive. Currently defined are: </p>
-<p><b>sql</b> - format the string suitable for a SQL statement. This will
-replace single quotes ("'") by two single quotes ("''") inside each field. This
-option MUST be specified when a template is used for writing to a database,
-otherwise SQL injection might occur.<br>
+<p><b>sql</b> - format the string suitable for a SQL statement in MySQL format. This will
+replace single quotes ("'") and the backslash character by their
+backslash-escaped counterpart ("\'" and "\\") inside each field. Please note
+that in MySQL configuration, the <code class="literal">NO_BACKSLASH_ESCAPES</code>
+mode must be turned off for this format to work (this is the default).</p>
+<p><b>stdsql</b> - format the string suitable for a SQL statement that is to be
+sent to a standards-compliant sql server. This will
+replace single quotes ("'") by two single quotes ("''") inside each field.
+You must use stdsql together with MySQL if in MySQL configuration the
+<code class="literal">NO_BACKSLASH_ESCAPES</code> is turned on.</p>
+<p>Either the <b>sql</b> or <b>stdsql</b>
+option <b>must</b> be specified when a template is used for writing to a database,
+otherwise injection might occur. Please note that due to the unfortunate fact
+that several vendors have violated the sql standard and introduced their own
+escape methods, it is impossible to have a single option doing all the work.
+So you yourself must make sure you are using the right format. <b>If you choose
+the wrong one, you are still vulnerable to sql injection.</b><br>
<br>
Please note that the database writer *checks* that the sql option is present in
the template. If it is not present, the write database action is disabled. This
@@ -67,7 +80,13 @@ to SQL injection. The sql option can also be useful with files - especially if you want to import them into a database on another machine for performance
reasons. However, do NOT use it if you do not have a real need for it - among
others, it takes some toll on the processing time. Not much, but on a really
-busy system you might notice it ;)<br>
+busy system you might notice it ;)</p>
+<p>The default template for the write to database action has the sql option set.
+As we currently support only MySQL and the sql option matches the default MySQL
+configuration, this is a good choice. However, if you have turned on
+<code class="literal">NO_BACKSLASH_ESCAPES</code> in your MySQL config, you need
+to supply a template with the stdsql option. Otherwise you will become
+vulnerable to SQL injection. <br>
<br>
To escape:<br>
% = \%<br>
@@ -315,6 +334,33 @@ the connect information. This is as follows:<br> Output channel actions must start with a $-sign, e.g. if you would like to bind
your output channel definition "mychannel" to the action, use "$mychannel".
Output channels support template definitions like all all other actions.</p>
+<h3>Shell Execute</h3>
+<p>This executes a program in a subshell. The programm is passed the
+template-generated message as the only command line parameter. Rsyslog waits
+until the program terminates and only then continues to run.</p>
+<p>^programm-to-execute;template</p>
+<p>The program-to-execute can be any valid executable.</p>
+<p><b>WARNING:</b> The Shell Execute action was added to serve an urgent need.
+While it is considered reasonable save when used with some thinking, its
+implications must be considered. The current implementation uses a system() call
+to execute the command. This is not the best way to do it (and will hopefully
+changed in further releases). Also, proper escaping of special characters is
+done to prevent command injection. However, attackers always find smart ways to
+circumvent escaping, so we can not say if the escaping applied will really safe
+you from all hassles. Lastely, rsyslog will wait until the shell command
+terminates. Thus, a program error in it (e.g. an infinite loop) can actually
+disable rsyslog. Even without that, during the programs run-time no messages are
+processed by rsyslog. As the IP stacks buffers are quickly overflowed, this
+bears an increased risk of message loss. You must be aware of these implications.
+Even though they are severe, there are several cases where the "shell execute"
+action is very useful. This is the reason why we have included it in its current
+form. To mitigate its risks, always a) test your program thouroughly, b) make
+sure its runtime is as short as possible (if it requires a longer run-time, you
+might want to spawn your own sub-shell asynchronously), c) apply proper
+firewalling so that only known senders can send syslog messages to rsyslog.
+Point c) is especially important: if rsyslog is accepting message from any hosts,
+chances are much higher that an attacker might try to exploit the "shell execute"
+action.</p>
<h2>TEMPLATE NAME</h2>
<p>Every ACTION can be followed by a template name. If so, that template is used
for message formatting. If no name is given, a hardcoded default template is
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