truncated mech names are accepted - a bug?

Hello,

A server with this configuration:
mech_list: A

shows 'ANONYMOUS' in available mechanisms.

It's due to the fact that _sasl_is_equal_mech() compares plug_mech only with the first strlen(req_mech) characters of plug_mech:
lib/common.c:2431:    return (strncasecmp(req_mech, plug_mech, n) == 0);

where n is (usually) an equivalent of strlen(req_mech)

For ANONYMOUS, it means that any string from the following set of
 {A, AN, ..., ANONYMOU, ANONYMOUS} will match ANONYMOUS.

The fix could be to first compare the length of plug_mech with 'n'.

This might be also a feature - to allow multiple plugin mechanism using one mech_list string,
but it doesn't feel right for me as I haven't found any documentation about that.


Petr
-- 
Petr Lautrbach
Security Technologies
Red Hat

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