Re: (ITS#9137) slappasswd generate wrong SSHA from file - openldap-bugs

12 Dec 2019


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On 12/12/2019 14:02, Howard Chu wrote:
...
antoine.tran@thales-services.fr wrote:
...
Full_Name: Antoine TRAN
Version: openldap-servers-2.4.44-21.el7_6.x86_64
OS: CentOS Linux release 7.7.1908 (Core)
URL: ftp://ftp.openldap.org/incoming/
Submission from: (NULL) (213.190.88.94)
I use slappasswd to generate SSHA password. The issue is it behavior is
different whether I submit the password - in stdin or in command-line '-s' - and
from a secret file '-T'. Command:
slappasswd -h {SSHA}
=> write 'd' twice as password
slappasswd -h {SSHA} -s d
provides working SSHA.
But:
echo d >/run/secrets/rootpw
slappasswd -h {SSHA} -T /run/secrets/rootpw
provides a valid SSHA, but that does not match the password.
My multiple test are done by replacing rootpw in /etc/openldap/slapd.conf,
regenerating with:
systemctl stop slapd
sed -i -e "s,rootpw .*$,rootpw ${ROOTPW_HASH},g" /etc/openldap/slapd.conf
slapcat -n 0 -f /etc/openldap/slapd.conf -F /etc/openldap/slapd.d
systemctl start slapd
ldapsearch -D "${ROOTDN}" -w "${ROOTPW}"
The content of the secret file can be "d" or "d\n", it does not make a
difference. Also, if I change the schema from SSHA to just a fixed salt, the
'-T' seems to work as expected:
(a) slappasswd -c 123
=> write d twice
(b) slappasswd -c 123 -s 123
(c) slappasswd -c 123 -T /run/secrets/rootpw
(a), (b) and (c) gives the exact same hash. But I cannot put a fixed salt and
use SSHA, slappasswd prevents me from that, with an error schema already
provided.
Unable to reproduce, SSHA works fine here.
Obviously you can't use a fixed salt with SSHA, that's the point of its salt is to
be random and different every time.
I wanted to override the salt as a test, to check if we have the same 
output with a file and in command-line. But I found another way to test.
...
When using a password in a file you must ensure the trailing '\n' is omitted. This
is already documented in the manpage.
I did read and checked this point. I have written that I did not have a 
newline. But here is a simple and reproducible test, that took me some 
long time. In a Linux machine with internet, just copy paste this:
docker run --name slappasswd --rm -ti centos:7 bash
yum install openldap-servers -y
cat <<EOF >/makeSecret.py
    import os
    import sys
    import hashlib
    from base64 import urlsafe_b64encode as encode
    from base64 import urlsafe_b64decode as decode
def makeSecret(password):
         salt = os.urandom(4)
         h = hashlib.sha1(password)
         h.update(salt)
         return "{SSHA}" + encode(h.digest() + salt)
if __name__ == '__main__':
         print(makeSecret(sys.argv[1]))
    EOF
cat <<EOF >/checkPassword.py
    import os
    import sys
    import hashlib
    from base64 import urlsafe_b64encode as encode
    from base64 import urlsafe_b64decode as decode
def checkPassword(challenge_password, password):
         challenge_bytes = decode(challenge_password[6:])
         digest = challenge_bytes[:20]
         salt = challenge_bytes[20:]
         hr = hashlib.sha1(password)
         hr.update(salt)
         return digest == hr.digest()
if __name__ == '__main__':
         print(checkPassword(sys.argv[1], sys.argv[2]))
    EOF
python /checkPassword.py $(python /makeSecret.py d) d
python /checkPassword.py $(slappasswd -s d) d
mkdir -p /run/secrets/
    echo d>/run/secrets/rootpw
    python /checkPassword.py $(slappasswd -T /run/secrets/rootpw) d
    echo Begin-$(cat /run/secrets/rootpw)-End
    # => shows no newline:
    #Begin-d-End
It will show you that all hash works except the part with slappasswd -T, 
and I checked the newline.
...
...
I saw the same issue in another openldap mail:
https://www.openldap.org/lists/openldap-software/200805/msg00060.html but no
answer.
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    On 12/12/2019 14:02, Howard Chu wrote:<br>
    <blockquote type="cite"
      cite="mid:c5070626-b60e-28f5-38a3-7871c8a0cbec@symas.com">
      <pre class="moz-quote-pre" wrap=""><a class="moz-txt-link-abbreviated" href="mailto:antoine.tran@thales-services.fr">antoine.tran@thales-services.fr</a> wrote:
</pre>
      <blockquote type="cite">
        <pre class="moz-quote-pre" wrap="">Full_Name: Antoine TRAN
Version: openldap-servers-2.4.44-21.el7_6.x86_64
OS: CentOS Linux release 7.7.1908 (Core)
URL: <a class="moz-txt-link-freetext" href="ftp://ftp.openldap.org/incoming/">ftp://ftp.openldap.org/incoming/</a>
Submission from: (NULL) (213.190.88.94)
I use slappasswd to generate SSHA password. The issue is it behavior is
different whether I submit the password - in stdin or in command-line '-s' - and
from a secret file '-T'. Command:
slappasswd -h {SSHA}
=&gt; write 'd' twice as password
slappasswd -h {SSHA} -s d
provides working SSHA.
But:
echo d &gt;/run/secrets/rootpw
slappasswd -h {SSHA} -T /run/secrets/rootpw
provides a valid SSHA, but that does not match the password.
My multiple test are done by replacing rootpw in /etc/openldap/slapd.conf,
regenerating with:
systemctl stop slapd
sed -i -e "s,rootpw .*$,rootpw ${ROOTPW_HASH},g" /etc/openldap/slapd.conf
slapcat -n 0 -f /etc/openldap/slapd.conf -F /etc/openldap/slapd.d
systemctl start slapd
ldapsearch -D "${ROOTDN}" -w "${ROOTPW}"
The content of the secret file can be "d" or "d\n", it does not make a
difference. Also, if I change the schema from SSHA to just a fixed salt, the
'-T' seems to work as expected:
(a) slappasswd -c 123
=&gt; write d twice
(b) slappasswd -c 123 -s 123
(c) slappasswd -c 123 -T /run/secrets/rootpw
(a), (b) and (c) gives the exact same hash. But I cannot put a fixed salt and
use SSHA, slappasswd prevents me from that, with an error schema already
provided.
</pre>
      </blockquote>
      <pre class="moz-quote-pre" wrap="">
Unable to reproduce, SSHA works fine here.
Obviously you can't use a fixed salt with SSHA, that's the point of its salt is to
be random and different every time.</pre>
    </blockquote>
    I wanted to override the salt as a test, to check if we have the
    same output with a file and in command-line. But I found another way
    to test.<br>
    <blockquote type="cite"
      cite="mid:c5070626-b60e-28f5-38a3-7871c8a0cbec@symas.com">
      <pre class="moz-quote-pre" wrap="">
When using a password in a file you must ensure the trailing '\n' is omitted. This
is already documented in the manpage.</pre>
    </blockquote>
    <p>I did read and checked this point. I have written that I did not
      have a newline. But here is a simple and reproducible test, that
      took me some long time. In a Linux machine with internet, just
      copy paste this:</p>
    <blockquote>
      <p>docker run --name slappasswd --rm -ti centos:7 bash<br>
        <br>
        yum install openldap-servers -y<br>
        <br>
        cat &lt;&lt;EOF &gt;/makeSecret.py<br>
        import os<br>
        import sys<br>
        import hashlib<br>
        from base64 import urlsafe_b64encode as encode<br>
        from base64 import urlsafe_b64decode as decode<br>
        <br>
        def makeSecret(password):<br>
            salt = os.urandom(4)<br>
            h = hashlib.sha1(password)<br>
            h.update(salt)<br>
            return "{SSHA}" + encode(h.digest() + salt)<br>
        <br>
        if __name__ == '__main__':<br>
            print(makeSecret(sys.argv[1]))<br>
        EOF<br>
        <br>
        cat &lt;&lt;EOF &gt;/checkPassword.py<br>
        import os<br>
        import sys<br>
        import hashlib<br>
        from base64 import urlsafe_b64encode as encode<br>
        from base64 import urlsafe_b64decode as decode<br>
        <br>
        def checkPassword(challenge_password, password):<br>
            challenge_bytes = decode(challenge_password[6:])<br>
            digest = challenge_bytes[:20]<br>
            salt = challenge_bytes[20:]<br>
            hr = hashlib.sha1(password)<br>
            hr.update(salt)<br>
            return digest == hr.digest()<br>
        <br>
        if __name__ == '__main__':<br>
            print(checkPassword(sys.argv[1], sys.argv[2]))<br>
        EOF<br>
        <br>
        python /checkPassword.py $(python /makeSecret.py d) d<br>
        <br>
        python /checkPassword.py $(slappasswd -s d) d<br>
        <br>
        mkdir -p /run/secrets/<br>
        echo d&gt;/run/secrets/rootpw<br>
        python /checkPassword.py $(slappasswd -T /run/secrets/rootpw) d<br>
        echo Begin-$(cat /run/secrets/rootpw)-End<br>
        # =&gt; shows no newline:<br>
        #Begin-d-End<br>
      </p>
    </blockquote>
    <p>It will show you that all hash works except the part with
      slappasswd -T, and I checked the newline.<br>
      <br>
    </p>
    <blockquote type="cite"
      cite="mid:c5070626-b60e-28f5-38a3-7871c8a0cbec@symas.com">
      <pre class="moz-quote-pre" wrap="">
</pre>
      <blockquote type="cite">
        <pre class="moz-quote-pre" wrap="">
I saw the same issue in another openldap mail:
<a class="moz-txt-link-freetext" href="https://www.openldap.org/lists/openldap-software/200805/msg00060.html">https://www.openldap.org/lists/openldap-software/200805/msg00060.html</a> but no
answer.
</pre>
      </blockquote>
      <pre class="moz-quote-pre" wrap="">
</pre>
    </blockquote>
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