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I completely agree that this doesn't add any security when running slapd. However, when I originally wrote this patch, I was more targeting API usage, and in particular, client-side API usage. My goal was to allow a user to present an encrypted key (stored on disk) and a password (only held in memory), and use these to query a secure LDAP server. The issue of how the password got into memory is certainly beyond the scope of OpenLDAP in this case, but it certainly could be done securely in a way that wouldn't leave it exposed to a third-party with file-system access.
For example (in the use case that motivated me originally), an sysadmin could input the password through an online form, submit said form to a Python webserver over HTTPS, the Python code could pass the password to OpenLDAP through a Python interface like python-ldap ( https://www.python-ldap.org/), and then use the LDAPS or STARTTLS connection to talk securely to some LDAP server elsewhere. All without an unencrypted keyfile or a password ever existing on disk, hence the added security.
If you feel that supporting encrypted keyfiles in slapd is a bad design choice, I'm willing to rework the patch to drop that part and only keep the API-level support. Personally, I would argue that it doesn't hurt to support the feature, although perhaps my documentation changes could do a better job emphasizing the inherent security limitations. Let me know what you think (or if this discussion should take place on a list, let me know which/where).
On Wed, Feb 22, 2017 at 1:11 PM, Howard Chu hyc@symas.com wrote:
ahnolds@gmail.com wrote:
Full_Name: Alec Cooper Version: HEAD of master branch OS: Ubuntu Linux 16.04 URL: ftp://ftp.openldap.org/incoming/Alec-Cooper-160827.patch Submission from: (NULL) (73.134.243.211)
Adding support for encrypted server private keys.
Thank you for your submission. I must compliment you on providing such a comprehensive and well-written contribution. Unfortunately the feature itself is clearly not useful. Perhaps you should have raised this topic on the openldap-devel list for discussion before spending your time writing it.
All your feature does is embed the encryption key in the filesystem, so an encrypted private key is still no more secure than an unencrypted one. It still just depends on setting proper file access permissions, and the current documentation already makes that point.
Indeed, all it does is give the false illusion of enhancing security, and followups like balmerpeak92@gmail.com's shows that people will easily fall for such illusions.
I regret having to reject such a well written contribution, but we cannot in good conscience accept a security feature that doesn't actually improve security.
The meat of this patch is changes to tls2.c, tls_g.c, tls_m.c, and tls_o.c to send a password to the underlying TLS library.
Changes to ldap.h, init.c and ldap-int.h expose the new LDAP_OPT_X_TLS_KEYPASSWORD in the main API.
Changes in the contrib/ldapc++ directory expose the corresponding TlsOptions::KEYPASSWORD option in the C++ API.
Changes in the servers directory expose equivalent options for servers as configuration file entries or environment variables.
Changes in the doc directory add documentation about the new options and remove statements that indicated that encrypted keyfiles are not supported.
New files in the test directory are for testing TLS connections, both in general and with encrypted keyfiles. Tests pass for OpenSSL and GnuTLS using PEM formatted certs and keys, and for MozNSS using cert/key databases. The new unit test (test065-tls) has been written to detect when using NSS, and use the cert/key databases in this case. I have been unable to get a working version of libnsspem, so I cannot test MozNSS with (or without) encrypted keyfiles - testing for this case would be welcome!
Notice of origin: The attached patch file is derived from OpenLDAP Software. All of the modifications to OpenLDAP Software represented in the following patch were developed by Alec Cooper ahnolds@gmail.com. I have not assigned rights and/or interest in this work to any party. Rights statement: I, Alec Cooper, hereby place the following modifications to OpenLDAP Software (and only these modifications) into the public domain. Hence, these modifications may be freely used and/or redistributed for any purpose with or without attribution and/or other notice.
The patch has been uploaded to the OpenLDAP FTP server and can be found at ftp://ftp.openldap.org/incoming/Alec-Cooper-160827.patch
-- -- Howard Chu CTO, Symas Corp. http://www.symas.com Director, Highland Sun http://highlandsun.com/hyc/ Chief Architect, OpenLDAP http://www.openldap.org/project/
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<div dir=3D"ltr">I completely agree that this doesn't add any security = when running slapd. However, when I originally wrote this patch, I was more= targeting API usage, and in particular, client-side API usage. My goal was= to allow a user to present an encrypted key (stored on disk) and a passwor= d (only held in memory), and use these to query a secure LDAP server. The i= ssue of how the password got into memory is certainly beyond the scope of O= penLDAP in this case, but it certainly could be done securely in a way that= wouldn't leave it exposed to a third-party with file-system access.<di= v><br></div><div>For example (in the use case that motivated me originally)= , an sysadmin could input the password through an online form, submit said = form to a Python webserver over HTTPS, the Python code could pass the passw= ord to OpenLDAP through a Python interface like python-ldap (<a href=3D"htt= ps://www.python-ldap.org/">https://www.python-ldap.org/</a>), and then use = the LDAPS or STARTTLS connection to talk securely to some LDAP server elsew= here. All without an unencrypted keyfile or a password ever existing on dis= k, hence the added security.<div><br></div><div>If you feel that supporting= encrypted keyfiles in slapd is a bad design choice, I'm willing to rew= ork the patch to drop that part and only keep the API-level support. Person= ally, I would argue that it doesn't hurt to support the feature, althou= gh perhaps my documentation changes could do a better job emphasizing the i= nherent security limitations. Let me know what you think (or if this discus= sion should take place on a list, let me know which/where).=C2=A0</div></di= v><div><br></div></div><div class=3D"gmail_extra"><br><div class=3D"gmail_q= uote">On Wed, Feb 22, 2017 at 1:11 PM, Howard Chu <span dir=3D"ltr"><<a = href=3D"mailto:hyc@symas.com" target=3D"_blank">hyc@symas.com</a>></span=
wrote:<br><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;bo=
rder-left:1px #ccc solid;padding-left:1ex"><a href=3D"mailto:ahnolds@gmail.= com" target=3D"_blank">ahnolds@gmail.com</a> wrote:<br> <blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p= x #ccc solid;padding-left:1ex"> Full_Name: Alec Cooper<br> Version: HEAD of master branch<br> OS: Ubuntu Linux 16.04<br> URL: <a href=3D"ftp://ftp.openldap.org/incoming/Alec-Cooper-160827.patch" r= el=3D"noreferrer" target=3D"_blank">ftp://ftp.openldap.org/incomin<wbr>g/Al= ec-Cooper-160827.patch</a><br> Submission from: (NULL) (73.134.243.211)<br> <br> <br> Adding support for encrypted server private keys.<br> </blockquote> <br> Thank you for your submission. I must compliment you on providing such a co= mprehensive and well-written contribution. Unfortunately the feature itself= is clearly not useful. Perhaps you should have raised this topic on the op= enldap-devel list for discussion before spending your time writing it.<br> <br> All your feature does is embed the encryption key in the filesystem, so an = encrypted private key is still no more secure than an unencrypted one. It s= till just depends on setting proper file access permissions, and the curren= t documentation already makes that point.<br> <br> Indeed, all it does is give the false illusion of enhancing security, and f= ollowups like <a href=3D"mailto:balmerpeak92@gmail.com" target=3D"_blank">b= almerpeak92@gmail.com</a>'s shows that people will easily fall for such= illusions.<br> <br> I regret having to reject such a well written contribution, but we cannot i= n good conscience accept a security feature that doesn't actually impro= ve security.<br> <blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p= x #ccc solid;padding-left:1ex"> <br> The meat of this patch is changes to tls2.c, tls_g.c, tls_m.c, and tls_o.c = to<br> send a password to the underlying TLS library.<br> <br> Changes to ldap.h, init.c and ldap-int.h expose the new<br> LDAP_OPT_X_TLS_KEYPASSWORD in the main API.<br> <br> Changes in the contrib/ldapc++ directory expose the corresponding<br> TlsOptions::KEYPASSWORD option in the C++ API.<br> <br> Changes in the servers directory expose equivalent options for servers as<b= r> configuration file entries or environment variables.<br> <br> Changes in the doc directory add documentation about the new options and re= move<br> statements that indicated that encrypted keyfiles are not supported.<br> <br> New files in the test directory are for testing TLS connections, both in ge= neral<br> and with encrypted keyfiles. Tests pass for OpenSSL and GnuTLS using PEM<br=
formatted certs and keys, and for MozNSS using cert/key databases. The new = unit<br> test (test065-tls) has been written to detect when using NSS, and use the<b= r> cert/key databases in this case. I have been unable to get a working versio= n of<br> libnsspem, so I cannot test MozNSS with (or without) encrypted keyfiles -<b= r> testing for this case would be welcome!<br> <br> Notice of origin: The attached patch file is derived from OpenLDAP Software= . All<br> of the modifications to OpenLDAP Software represented in the following patc= h<br> were developed by Alec Cooper <a href=3D"mailto:ahnolds@gmail.com" target= =3D"_blank">ahnolds@gmail.com</a>. I have not assigned rights<br> and/or interest in this work to any party.<br> Rights statement: I, Alec Cooper, hereby place the following modifications = to<br> OpenLDAP Software (and only these modifications) into the public domain. He= nce,<br> these modifications may be freely used and/or redistributed for any purpose= with<br> or without attribution and/or other notice.<br> <br> The patch has been uploaded to the OpenLDAP FTP server and can be found at<= br> <a href=3D"ftp://ftp.openldap.org/incoming/Alec-Cooper-160827.patch" rel=3D= "noreferrer" target=3D"_blank">ftp://ftp.openldap.org/incomin<wbr>g/Alec-Co= oper-160827.patch</a><br> <br> <br><span class=3D"HOEnZb"><font color=3D"#888888"> </font></span></blockquote><span class=3D"HOEnZb"><font color=3D"#888888"> <br> <br> -- <br> =C2=A0 -- Howard Chu<br> =C2=A0 CTO, Symas Corp.=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0<a href=3D"= http://www.symas.com" rel=3D"noreferrer" target=3D"_blank">http://www.symas= .com</a><br> =C2=A0 Director, Highland Sun=C2=A0 =C2=A0 =C2=A0<a href=3D"http://highland= sun.com/hyc/" rel=3D"noreferrer" target=3D"_blank">http://highlandsun.com/h= yc/</a><br> =C2=A0 Chief Architect, OpenLDAP=C2=A0 <a href=3D"http://www.openldap.org/p= roject/" rel=3D"noreferrer" target=3D"_blank">http://www.openldap.org/proje= c<wbr>t/</a><br> </font></span></blockquote></div><br></div>
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ahnolds＠gmail.com