Can't authenticate using ARGON2ID crypt scheme from doveadm pw w/rounds != default

[Aki Tuomi]

The reason it fails is because auth process runs out of memory and there
is a bug in libsodium which causes it to crash in this scenario. The fix
is to do

service auth {

  vsz_limit = 0 # or 2G at least

}

Aki


On 26.09.2018 09:12, Keith Amidon wrote:
> I'm using dovecot version 2.3.2.1 (0719df592) and trying to use the
> ARGON2ID crypt scheme for authentication using the passdb passwd-file
> driver. My passdb config is very simple:
>
>     passdb {
>       driver = passwd-file
>       args = username_format=%u <path-to-file-here>
>     }
>
> If I generate a password this way:
>
>     doveadm pw -s ARGON2ID -p 'This is a test'
>
> I get a crypt value for the password that I can place in the password
> file like:
>
> testuser:{ARGON2ID}$argon2id$v=19$m=65536,t=3,p=1$UuqF25QtumNBe9R2FmUZvA$5avvHY5TIaj5Wl5C4k8BOI4bcmNei7BwPLlXYQVybMc
>
>
> And if I test authentication with this command:
>
>     doveadm auth login testuser 'This is a test'
>
> It works as shown by the (lightly redacted) log:
>
>     Sep 25 22:46:01 myhost dovecot[17538]: auth: Debug: auth client
> connected (pid=55417)
>     Sep 25 22:46:01 myhost dovecot[17538]: auth: Debug: client in:
> AUTH        1        PLAIN service=doveadm        debug       
> resp=<hidden>
>     Sep 25 22:46:01 myhost dovecot[17538]: auth: Debug:
> passwd-file(testuser): lookup: user=testuser file=<path-to-passwd-file>
>     Sep 25 22:46:01 myhost dovecot[17538]: auth: Debug: client passdb
> out: OK        1        user=testuser
>
> However, if I instead specify a non-default number of rounds this way:
>
>      doveadm pw -s ARGON2ID -p 'This is a test' -r 7
>
> and place the result in an entry in the password file like:
>
> testuser:{ARGON2ID}$argon2id$v=19$m=1048576,t=7,p=1$kIhnUR13GrtOvvpbJNJmnQ$o7O6Whxs3s8IE09yY9S2dPkJjJyEVc78GRFilYVS9fU
>
>
> Then testing authentication using the same command (repeated here):
>
>     doveadm auth login testuser 'This is a test'
>
> then authentication fails, as shown by this (lightly redacted) log:
>
>     Sep 25 22:52:05 myhost dovecot[17538]: auth: Debug: auth client
> connected (pid=55557)
>     Sep 25 22:52:05 myhost dovecot[17538]: auth: Debug: client in:
> AUTH        1        PLAIN service=doveadm        debug       
> resp=<hidden>
>     Sep 25 22:52:05 myhost dovecot[17538]: auth: Debug: passwd-file
> <path-to-passwd-file>: Read 3 users in 0 secs
>     Sep 25 22:52:05 myhost dovecot[17538]: auth: Debug:
> passwd-file(testuser): lookup: user=testuser file=<path-to-passwd-file>
>     Sep 25 22:52:05 myhost dovecot[17538]: auth:
> passwd-file(testuser): Password mismatch
>     Sep 25 22:52:07 myhost dovecot[17538]: auth: Debug: client passdb
> out: FAIL        1        user=testuser
>
> Experimentation with other values for the -r option has not produced
> a value that works for me. Using the exact same procedure but the
> BLF-CRYPT scheme, with varying number of rounds, does work.
>
> Am I doing something wrong or is there a bug in either the
> doveadm pw generation or the auth evaluation of the password?
>
> I'd like to use ARGON2ID with ~6 rounds if I can make this work.
> Any help would be greatly appreciated.
>
> Thanks, Keith
>