permissions Module
Miklos Tirpak
Edited by
Miklos Tirpak
Edited by
Bogdan-Andrei Iancu
Edited by
Juha Heinanen
Edited by
Irina-Maria Stanescu
Copyright © 2003 Miklos Tirpak
Copyright © 2006-2008 Juha Heinanen
Copyright © 2009 Irina-Maria Stanescu
Revision History
Revision $Revision: 6182 $ $Date: 2009-09-17 15:53:52 +0300
(Thu, 17 Sep 2009) $
__________________________________________________________
Table of Contents
1. Admin Guide
1.1. Overview
1.1.1. Call Routing
1.1.2. Registration Permissions
1.1.3. URI Permissions
1.1.4. Address Permissions
1.2. Dependencies
1.2.1. OpenSIPS Modules
1.2.2. External Libraries or Applications
1.3. Exported Parameters
1.3.1. default_allow_file (string)
1.3.2. default_deny_file (string)
1.3.3. check_all_branches (integer)
1.3.4. allow_suffix (string)
1.3.5. deny_suffix (string)
1.3.6. db_url (string)
1.3.7. address_table (string)
1.3.8. grp_col (string)
1.3.9. ip_col (string)
1.3.10. mask_col (string)
1.3.11. port_col (string)
1.3.12. proto_col (string)
1.3.13. pattern_col (string)
1.3.14. info_col (string)
1.4. Exported Functions
1.4.1. allow_routing()
1.4.2. allow_routing(basename)
1.4.3. allow_routing(allow_file,deny_file)
1.4.4. allow_register(basename)
1.4.5. allow_register(allow_file, deny_file)
1.4.6. allow_uri(basename, pvar)
1.4.7. check_address(group_id, ip, port, proto [,
context_info [, pattern]])
1.4.8. check_source_address(group_id [, context_info
[, pattern]])
1.4.9. get_source_group()
1.5. Exported MI Functions
1.5.1. address_reload
1.5.2. address_dump
1.5.3. subnet_dump
1.5.4. allow_uri
List of Examples
1.1. Set default_allow_file parameter
1.2. Set default_deny_file parameter
1.3. Set check_all_branches parameter
1.4. Set allow_suffix parameter
1.5. Set deny_suffix parameter
1.6. Set db_url parameter
1.7. Set address_table parameter
1.8. Set grp_col parameter
1.9. Set ip_col parameter
1.10. Set mask_col parameter
1.11. Set port_col parameter
1.12. Set proto_col parameter
1.13. Set pattern_col parameter
1.14. Set info_col parameter
1.15. allow_routing usage
1.16. allow_routing(basename) usage
1.17. allow_routing(allow_file, deny_file) usage
1.18. allow_register(basename) usage
1.19. allow_register(allow_file, deny_file) usage
1.20. allow_uri(basename, pvar) usage
1.21. check_address() usage
1.22. check_source_address() usage
1.23. get_source_group() usage
Chapter 1. Admin Guide
1.1. Overview
1.1.1. Call Routing
The module can be used to determine if a call has appropriate
permission to be established. Permission rules are stored in
plaintext configuration files similar to hosts.allow and
hosts.deny files used by tcpd.
When allow_routing function is called it tries to find a rule
that matches selected fields of the message.
OpenSIPS is a forking proxy and therefore a single message can
be sent to different destinations simultaneously. When checking
permissions all the destinations must be checked and if one of
them fails, the forwarding will fail.
The matching algorithm is as follows, first match wins:
* Create a set of pairs of form (From, R-URI of branch 1),
(From, R-URI of branch 2), etc.
* Routing will be allowed when all pairs match an entry in
the allow file.
* Otherwise routing will be denied when one of pairs matches
an entry in the deny file.
* Otherwise, routing will be allowed.
A non-existing permission control file is treated as if it were
an empty file. Thus, permission control can be turned off by
providing no permission control files.
From header field and Request-URIs are always compared with
regular expressions! For the syntax see the sample file:
config/permissions.allow.
1.1.2. Registration Permissions
In addition to call routing it is also possible to check
REGISTER messages and decide--based on the configuration
files--whether the message should be allowed and the
registration accepted or not.
Main purpose of the function is to prevent registration of
"prohibited" IP addresses. One example, when a malicious user
registers a contact containing IP address of a PSTN gateway, he
might be able to bypass authorization checks performed by the
SIP proxy. That is undesirable and therefore attempts to
register IP address of a PSTN gateway should be rejected. Files
config/register.allow and config/register.deny contain an
example configuration.
Function for registration checking is called allow_register and
the algorithm is very similar to the algorithm described in
Section 1.1.1, "Call Routing". The only difference is in the
way how pairs are created.
Instead of From header field the function uses To header field
because To header field in REGISTER messages contains the URI
of the person being registered. Instead of the Request-URI of
branches the function uses Contact header field.
Thus, pairs used in matching will look like this: (To, Contact
1), (To, Contact 2), (To, Contact 3), and so on..
The algorithm of matching is same as described in
Section 1.1.1, "Call Routing".
1.1.3. URI Permissions
The module can be used to determine if request is allowed to
the destination specified by an URI stored in a pvar.
Permission rules are stored in plaintext configuration files
similar to hosts.allow and hosts.deny used by tcpd.
When allow_uri function is called, it tries to find a rule that
matches selected fields of the message. The matching algorithm
is as follows, first match wins:
* Create a pair <From URI, URI stored in pvar>.
* Request will be allowed when the pair matches an entry in
the allow file.
* Otherwise request will be denied when the pair matches an
entry in the deny file.
* Otherwise, request will be allowed.
A non-existing permission control file is treated as if it were
an empty file. Thus, permission control can be turned off by
providing no permission control files.
From URI and URI stored in pvar are always compared with
regular expressions! For the syntax see the sample file:
config/permissions.allow.
1.1.4. Address Permissions
The module can be used to determine if an address (IP address
and port) matches any of the IP subnets stored in cached
OpenSIPS database table. Port 0 in cached database table
matches any port. Group ID, IP address, port and transport
protocol values to be matched can be either taken from the
request (check_source_address) or given as pvar arguments or
directly as strings(check_address).
Addresses stored in cached database table can be grouped
together into one or more groups specified by a group
identifier (unsigned integer). Group identifier is given as
argument to check_address and check_source_address.
Otherwise the request is rejected.
The address database table is specified by module parameters.
1.2. Dependencies
1.2.1. OpenSIPS Modules
The following modules must be loaded before this module:
* No dependencies on other OpenSIPS modules.
1.2.2. External Libraries or Applications
The following libraries or applications must be installed
before running OpenSIPS with this module loaded:
* None.
1.3. Exported Parameters
1.3.1. default_allow_file (string)
Default allow file used by functions without parameters. If you
don't specify full pathname then the directory in which is the
main config file is located will be used.
Default value is "permissions.allow".
Example 1.1. Set default_allow_file parameter
...
modparam("permissions", "default_allow_file", "/etc/permissions.allow")
...
1.3.2. default_deny_file (string)
Default file containing deny rules. The file is used by
functions without parameters. If you don't specify full
pathname then the directory in which the main config file is
located will be used.
Default value is "permissions.deny".
Example 1.2. Set default_deny_file parameter
...
modparam("permissions", "default_deny_file", "/etc/permissions.deny")
...
1.3.3. check_all_branches (integer)
If set then allow_routing functions will check Request-URI of
all branches (default). If disabled then only Request-URI of
the first branch will be checked.
Warning
Do not disable this parameter unless you really know what you
are doing.
Default value is 1.
Example 1.3. Set check_all_branches parameter
...
modparam("permissions", "check_all_branches", 0)
...
1.3.4. allow_suffix (string)
Suffix to be appended to basename to create filename of the
allow file when version with one parameter of either
allow_routing or allow_register is used.
Note
Including leading dot.
Default value is ".allow".
Example 1.4. Set allow_suffix parameter
...
modparam("permissions", "allow_suffix", ".allow")
...
1.3.5. deny_suffix (string)
Suffix to be appended to basename to create filename of the
deny file when version with one parameter of either
allow_routing or allow_register is used.
Note
Including leading dot.
Default value is ".deny".
Example 1.5. Set deny_suffix parameter
...
modparam("permissions", "deny_suffix", ".deny")
...
1.3.6. db_url (string)
This is URL of the database to be used.
Default value is "NULL".
Example 1.6. Set db_url parameter
...
modparam("permissions", "db_url", "dbdriver://username:password@dbhost/d
bname")
...
1.3.7. address_table (string)
Name of database table containing matching rules used by
allow_register function.
Default value is "address".
Example 1.7. Set address_table parameter
...
modparam("permissions", "address_table", "pbx")
...
1.3.8. grp_col (string)
Name of address table column containing group identifier of the
address.
Default value is "grp".
Example 1.8. Set grp_col parameter
...
modparam("permissions", "grp_col", "group_id")
...
1.3.9. ip_col (string)
Name of address table column containing IP address part of the
address.
Default value is "ip".
Example 1.9. Set ip_col parameter
...
modparam("permissions", "ip_col", "ipess")
...
1.3.10. mask_col (string)
Name of address table column containing network mask of the
address. Possible values are 0-32.
Default value is "mask".
Example 1.10. Set mask_col parameter
...
modparam("permissions", "mask_col", "subnet_length")
...
1.3.11. port_col (string)
Name of address table column containing port part of the
address.
Default value is "port".
Example 1.11. Set port_col parameter
...
modparam("permissions", "port_col", "prt")
...
1.3.12. proto_col (string)
Name of address table column containing transport protocol that
is matched against transport protocol of received request.
Possible values that can be stored in proto_col are "any",
"udp", "tcp", "tls", "sctp", and "none". Value "any" matches
always and value "none" never.
Default value is "proto".
Example 1.12. Set proto_col parameter
...
modparam("permissions", "proto_col", "transport")
...
1.3.13. pattern_col (string)
Name of address table column containing regular expression that
is matched against the arguments received by check_address or
check_source_address.
Default value is "pattern".
Example 1.13. Set pattern_col parameter
...
modparam("permissions", "pattern_col", "regexp")
...
1.3.14. info_col (string)
Name of address table column containing a string that is added
as value to a pvar given as argument to check_address or
check_source_address in case the function succedes.
Default value is "context_info".
Example 1.14. Set info_col parameter
...
modparam("permissions", "info_col", "info_col")
...
1.4. Exported Functions
1.4.1. allow_routing()
Returns true if all pairs constructed as described in
Section 1.1.1, "Call Routing" have appropriate permissions
according to the configuration files. This function uses
default configuration files specified in default_allow_file and
default_deny_file.
This function can be used from REQUEST_ROUTE, FAILURE_ROUTE.
Example 1.15. allow_routing usage
...
if (allow_routing()) {
t_relay();
};
...
1.4.2. allow_routing(basename)
Returns true if all pairs constructed as described in
Section 1.1.1, "Call Routing" have appropriate permissions
according to the configuration files given as parameters.
Meaning of the parameters is as follows:
* basename - Basename from which allow and deny filenames
will be created by appending contents of allow_suffix and
deny_suffix parameters.
If the parameter doesn't contain full pathname then the
function expects the file to be located in the same
directory as the main configuration file of the server.
This function can be used from REQUEST_ROUTE, FAILURE_ROUTE.
Example 1.16. allow_routing(basename) usage
...
if (allow_routing("basename")) {
t_relay();
};
...
1.4.3. allow_routing(allow_file,deny_file)
Returns true if all pairs constructed as described in
Section 1.1.1, "Call Routing" have appropriate permissions
according to the configuration files given as parameters.
Meaning of the parameters is as follows:
* allow_file - File containing allow rules.
If the parameter doesn't contain full pathname then the
function expects the file to be located in the same
directory as the main configuration file of the server.
* deny_file - File containing deny rules.
If the parameter doesn't contain full pathname then the
function expects the file to be located in the same
directory as the main configuration file of the server.
This function can be used from REQUEST_ROUTE, FAILURE_ROUTE.
Example 1.17. allow_routing(allow_file, deny_file) usage
...
if (allow_routing("rules.allow", "rules.deny")) {
t_relay();
};
...
1.4.4. allow_register(basename)
The function returns true if all pairs constructed as described
in Section 1.1.2, "Registration Permissions" have appropriate
permissions according to the configuration files given as
parameters.
Meaning of the parameters is as follows:
* basename - Basename from which allow and deny filenames
will be created by appending contents of allow_suffix and
deny_suffix parameters.
If the parameter doesn't contain full pathname then the
function expects the file to be located in the same
directory as the main configuration file of the server.
This function can be used from REQUEST_ROUTE, FAILURE_ROUTE.
Example 1.18. allow_register(basename) usage
...
if (method=="REGISTER") {
if (allow_register("register")) {
save("location");
exit;
} else {
sl_send_reply("403", "Forbidden");
};
};
...
1.4.5. allow_register(allow_file, deny_file)
The function returns true if all pairs constructed as described
in Section 1.1.2, "Registration Permissions" have appropriate
permissions according to the configuration files given as
parameters.
Meaning of the parameters is as follows:
* allow_file - File containing allow rules.
If the parameter doesn't contain full pathname then the
function expects the file to be located in the same
directory as the main configuration file of the server.
* deny_file - File containing deny rules.
If the parameter doesn't contain full pathname then the
function expects the file to be located in the same
directory as the main configuration file of the server.
This function can be used from REQUEST_ROUTE, FAILURE_ROUTE.
Example 1.19. allow_register(allow_file, deny_file) usage
...
if (method=="REGISTER") {
if (allow_register("register.allow", "register.deny")) {
save("location");
exit;
} else {
sl_send_reply("403", "Forbidden");
};
};
...
1.4.6. allow_uri(basename, pvar)
Returns true if the pair constructed as described in
Section 1.1.3, "URI Permissions" have appropriate permissions
according to the configuration files specified by the
parameter.
Meaning of the parameter is as follows:
* basename - Basename from which allow and deny filenames
will be created by appending contents of allow_suffix and
deny_suffix parameters.
If the parameter doesn't contain full pathname then the
function expects the file to be located in the same
directory as the main configuration file of the server.
* pvar - Any pseudo-variable defined in OpenSIPS.
This function can be used from REQUEST_ROUTE, FAILURE_ROUTE.
Example 1.20. allow_uri(basename, pvar) usage
...
if (allow_uri("basename", "$rt")) { // Check Refer-To URI
t_relay();
};
if (allow_uri("basename", "$avp(i:705)") { // Check URI stored in $avp(
i:705)
t_relay();
};
...
1.4.7. check_address(group_id, ip, port, proto [, context_info [,
pattern]])
Returns 1 if group id, IP address, port and protocol given as
arguments match an IP subnet found in cached address table, as
described in Section 1.1.4, "Address Permissions" . The
function takes 4 mandatory arguments and 2 optional ones.
This function can be useful to check if a request can be
allowed without authentication.
Meaning of the parameter is as follows:
* group_id
This argument represents the group id to be matched. It can
be an integer string or a string pvar. If the group_id
argument is "0", the query can match any group in the
cached address table.
* ip
This argument represents the ip address to be matched. It
can be an given directly as string or as a string pvar.
This argument cannot be null/empty.
* port
This argument represents the port to be matched. It can be
an given as an integer string or as a string pvar. Cached
address table entry containing port value 0 matches any
port. Also, a "0" value for the argument can match any port
in the address table.
* proto
This argument represents the protocol used for transport;
it can be an given as string or as string pvar. Transport
protocol is either "ANY" or any valid transport protocol
value: "UDP, "TCP", "TLS", and "SCTP".
* context_info
This argument represents the pvar in wich the context_info
field from the cached address table will be stored in case
of match. This argument is optional.
* pattern
This argument is a string to be matched with the regular
expression pattern field from the cached address table.
This argument is optional.
This function can be used from REQUEST_ROUTE, FAILURE_ROUTE.
Example 1.21. check_address() usage
...
// Checks if the tuple IP address/port (given as strings) and source pro
tocol
// (given as pvar), belongs to group 4, verifies if pattern string "text
test"
// matches the regular expression field in the database table and stores
the
// context information in $avp(i:10)
if (check_address("4","192.168.2.135","5700","$proto","$avp(i:10)", "tex
ttest")) {
t_relay();
xlog("$avp(i:10)\n");
}
...
// Checks if the tuple IP address/port/protocol of the source message is
in group
// 4 and stores context information in $avp(i:10)
if (check_address("4","$si","$sp","$proto")) {
t_relay();
}
...
// Checks if the tuple IP address/port/protocol stored in AVPs s:ip/s:po
rt/s:proto
// is in group 4 and stores context information in $avp(i:10)
$avp(s:ip) = "192.168.2.135";
$avp(s:port) = 5061;
$avp(s:proto) = "any";
if (check_address("4","$avp(s:ip)","$avp(s:port)","$avp(s:proto)","$avp(
i:10))) {
t_relay();
xlog("$avp(i:10)\n");
}
...
// Checks if the tuple IP address/port (given as strings) and source pro
tocol
// (given as pvar) is in group 4, verifies if pattern string "texttest"
matches
// the regular expression field in the database table, without storing a
ny
// context information
if (check_address("4","$si","5700","$proto","", "texttest")) {
t_relay();
}
...
1.4.8. check_source_address(group_id [, context_info [, pattern]])
Equivalent to check_address(group_id, "$si", "$sp", "$proto",
context_info, pattern).
This function can be used from REQUEST_ROUTE, FAILURE_ROUTE.
Example 1.22. check_source_address() usage
...
// Check if source address/port/proto is in group 4 and stores
// context information in $avp(i:9)
if (check_source_address("4","$avp(i:9)")) {
xlog("$avp(i:9)\n");
}else {
sl_send_reply("403", "Forbidden");
}
...
1.4.9. get_source_group()
Checks if an entry with the source ip/port/protocol is found in
cached address or subnet table in any group. If yes, returns
that group. If not returns -1. Port value 0 in cached address
and subnet table matches any port.
This function can be used from REQUEST_ROUTE, FAILURE_ROUTE.
Example 1.23. get_source_group() usage
...
$var(group) = get_source_group();
if ($var(group) != -1) {
# do something with $var(group)
};
...
1.5. Exported MI Functions
1.5.1. address_reload
Causes permissions module to re-read the contents of the
address database table into cache memory. In cache memory the
entries are for performance reasons stored in two different
tables: address table and subnet table depending on the value
of the mask field (32 or smaller).
Parameters: none
1.5.2. address_dump
Causes permissions module to dump contents of the address table
from cache memory.
Parameters: none
1.5.3. subnet_dump
Causes permissions module to dump contents of cache memory
subnet table.
Parameters: none
1.5.4. allow_uri
Tests if (URI, Contact) pair is allowed according to allow/deny
files. The files must already have been loaded by OpenSIPS.
Parameters:
* basename - Basename from which allow and deny filenames
will be created by appending contents of allow_suffix and
deny_suffix parameters.
* URI - URI to be tested
* Contact - Contact to be tested
