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<h1>ACL implementation in docman</h1> |
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<p>ACL implementation in docman is called <b>trustees</b>. It's based on |
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concept of trustees for Linux kernel by Vyacheslav Zavadsky |
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<zavadsky@braysystems.com> |
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</p> |
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|
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<p>Trustees are used to control access right, and special features |
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(like <a href="notify.html">notify on change</a>) |
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</p> |
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|
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<p>For each path (which can be file or directory) all trustees are |
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evaluated. However, <b>deny</b> has precedence over <b>allow</b> (which |
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is default in no trustee is specified). |
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</p> |
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|
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<h2>Format of trustee file</h2> |
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|
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<p>Comments are written using hash (#) as first character in line |
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<br><tt># this is a comment</tt></p> |
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|
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<p>Group can be used instead of user-name in all ACL. You can't have user |
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which has same name as group or vice-versa. It's written using plus (+) as |
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first character in line. |
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<br>+<i>group</i>:<i>user</i>[,<i>user</i>...]</p> |
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|
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<p>ACL is defined |
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<br><i>path</i>[<i>file</i>]<b>:</b>(<i>user</i>|<i>+group</i>|*)[,<i>user</i>...]:[<i>modifier</i>]<i>permission</i>[:...]</p> |
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|
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Valid modifiers: |
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<ul> |
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<li><tt>!</tt> trustee applies to all except user or group |
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<li><tt>C</tt> clear the permission (default is to set) |
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<li><tt>D</tt> deny access (default is grant) |
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<li><tt>O</tt> one-level trustee only <small>(this means that those permissions |
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will not be inherited on directories and files downwards from current |
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level -- it's useful for <a href="#anonymous">anonymous access</a>) |
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</small> |
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</ul> |
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|
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Valid permissions: |
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<ul> |
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<li><tt>R</tt> read (file) |
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<li><tt>W</tt> write (file) |
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<li><tt>B</tt> browse (directory) |
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<li><tt>N</tt> <a href="notify.html">notify</a> (e-mail change) |
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</ul> |
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|
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<h2>Examples</h2> |
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|
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<pre> |
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# dpavlin is administrator (grant all access to members of root group) |
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+root:dpavlin |
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/:root:RWB |
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# give read-only access to all users |
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/:*:R |
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# anyone can write in this file |
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/public_write.txt:*:w |
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# let just joe access secret file |
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/secret:joe:!CRW |
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</pre> |
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|
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<p>There is major difference between <b>deny</b> and <b>clear</b>. If you |
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want to deny access to one file except to use joe (which should have |
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read-only access) you could write: |
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|
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<pre> |
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/secret.txt:*:DRWB:joe:R |
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</pre> |
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That is wrong. <b>deny</b> rules will take precedence over allow read |
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to joe. So, you should write: |
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|
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<pre> |
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/secret.txt:*:CRWB:joe:R |
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</pre> |
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Which will work. |
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<p>If you want to allow just one user (<i>editor</i>) to have write |
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persmissions on file <i>one_editor.txt</i> while all others can read it, you |
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could do something like: |
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|
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<pre> |
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/one_editor.txt:*:DW:editor:CRWB |
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</pre> |
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Order of statements is not important. Trustees are always evaluated from |
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universal ones (e.g. ones for all users; with *) to specific for this |
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user (in this case, for user <i>editor</i>). However, this example |
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wouldn't work without <b>C</b> for user <i>editor</i> because <b>deny</b> |
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for write would have precidence. |
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|
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<p> |
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<big>FIX</big> write more examples, better descriptions... |
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</p> |
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|
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<a name="anonymous"> |
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<h3>Anonymous access</h3> |
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<p>One of great advantages of using trustees is that you can allow |
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anonymous access (without login). You should pay attention to access |
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right, because you probably don't want anonymous users to see all files |
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or folders in your repository. |
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</p> |
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|
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<p>First, you will have to add browse trustee to anonymous user |
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on root directory -- docman will ignore all anonymous users if |
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you don't do this. |
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<pre> |
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/:anonymous:BO |
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</pre> |
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You really <b>want to use flags <tt>BO</tt></b> and not just <tt>B</tt> because |
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if you specify just <tt>B</tt> anonymous users will be able to browse (see |
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directory names) of your whole repository. This way you can explicitly |
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allow (or deny) which sub-directories you want anonymous users to browse. |
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<br>For example, this will allow anonymous users to see and read everything |
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in <tt>/pub</tt> and to store documents in <tt>/incoming</tt>: |
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<pre> |
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/pub:anonymous:RB |
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/incoming:anonymous:RWB |
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</pre> |
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You might also want to hide some directory from anonymous users, and you |
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can do that using: |
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<pre> |
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/private:anonymous:DB |
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</pre> |
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If you would like to <b>give all your users</b> which are authenticated via |
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login and password <b>all access</b> to all files (like in old docman v1.x) you |
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also have to add |
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<pre> |
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/:*:RWB |
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</pre> |
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However, that <b>will not add all |
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permission to anonymous users</b>. If you want to add all that permission |
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to anonymous users (which will create wiki-like community for sharing files) |
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you must explicitly say that you allow that to anonymous users: |
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<pre> |
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/:anonymous:RWB |
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</pre> |
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All those setting will create environment which is very like docman v1.x, |
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but with anonymous users allowed to see document in <tt>/pub</tt> and |
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upload them in <tt>/incoming</tt>. |
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</p> |
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<h2>Default security</h2> |
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<p>If none of trustee rules satisfy, default policy is <i>deny</i>. Basically, |
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you have to explicitly allow all your users access to files (which can be |
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as simple as <tt>/:*:RB</tt> to give <i>read</i> and <i>browse</i> to all |
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users) |
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</p> |
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<h2>docman without trustee configuration</h2> |
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<p>If you <b>don't have</b> <tt>realm/http_virtual_host.trustee</tt> you |
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will fall-back to default docman v1.x behavior: whole group will have |
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all right on all files except <i>anonymous</i> users (which won't be able |
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to login anyway). |
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</p> |
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|
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<p>See also: |
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<a href="admin.html">Administration manual</a> |
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</p> |
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