Presently, we have a bunch of machines under configuration management (using Puppet, but that's not really relevant here). I'm hoping to implement LDAP via nsswitch on these machines, but I've run into an issue: the standard getpw*(3) mechanisms can't tell the difference between users or groups in the local databases and those in the remote LDAP database. We need Puppet to manage entries for users and groups in the local database, without respect to what entries might be imported from LDAP (because they are supposed to override the data returned by LDAP). Puppet invokes pw(8) to actually perform the modifications, but I suspect it also uses native code from the Ruby standard library to actually do pre-modification lookups. Looking at the code in both nss-pam-ldapd and libc, it seems like the only plausible way to fix this is to add functionality to nsswitch which would allow it to use different configurations depending on the identity of the process invoking getpwnam(3) or getgrnam(3). Does anyone have opinions on how this ought to be implemented, or indeed how it could be implemented securely? (As a side issue, the net/nss-pam-ldapd port completely ignores account expiration dates. This bug is due to the fact that Linux has this ships-in-the-night "shadow" mechanism, getspent(3), rather than having it integrated in getpwent(3) like it should be, but the ultimate upshot is that if you're using nss-pam-ldapd you can't rely on shadowExpire attributes in the directory actually have an effect on FreeBSD. I'll open a bugzilla issue about this.) -GAWollman
-------- In message <22483.5592.653250.726711 at hergotha.csail.mit.edu>, Garrett Wollman w rites:> Puppet invokes pw(8) to actually perform the >modifications, but I suspect it also uses native code from the Ruby >standard library to actually do pre-modification lookups. >[...] >Looking at the code in both nss-pam-ldapd and libc, it seems like the >only plausible way to fix this is to add functionality to nsswitch >which would allow it to use different configurations depending on the >identity of the process invoking getpwnam(3) or getgrnam(3).You want to add a futher layer of complications to the the already far too complicated user/group/authentication code in FreeBSD, just because you don't want to look at Puppets Ruby code ? Really ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk at FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence.
You may find that the best way to handle this is to disable enumeration of your LDAP users in NSS. For example, if you're using sssd for your LDAP NSS & PAM provider, it is, in fact, disabled by default. This means that calls to getpwent(3) will only end up enumerating the users in your local files, and not those in LDAP. But, calls to getpwnam(3), getpwuid(3), etc will return the details of a specific username or user id, even if it's only present in LDAP. On Fri, Sep 9, 2016 at 4:11 PM Garrett Wollman <wollman at bimajority.org> wrote:> Presently, we have a bunch of machines under configuration management > (using Puppet, but that's not really relevant here). I'm hoping to > implement LDAP via nsswitch on these machines, but I've run into an > issue: the standard getpw*(3) mechanisms can't tell the difference > between users or groups in the local databases and those in the remote > LDAP database. We need Puppet to manage entries for users and groups > in the local database, without respect to what entries might be > imported from LDAP (because they are supposed to override the data > returned by LDAP). Puppet invokes pw(8) to actually perform the > modifications, but I suspect it also uses native code from the Ruby > standard library to actually do pre-modification lookups. > > Looking at the code in both nss-pam-ldapd and libc, it seems like the > only plausible way to fix this is to add functionality to nsswitch > which would allow it to use different configurations depending on the > identity of the process invoking getpwnam(3) or getgrnam(3). Does > anyone have opinions on how this ought to be implemented, or indeed > how it could be implemented securely? > > (As a side issue, the net/nss-pam-ldapd port completely ignores > account expiration dates. This bug is due to the fact that Linux has > this ships-in-the-night "shadow" mechanism, getspent(3), rather than > having it integrated in getpwent(3) like it should be, but the > ultimate upshot is that if you're using nss-pam-ldapd you can't rely > on shadowExpire attributes in the directory actually have an effect on > FreeBSD. I'll open a bugzilla issue about this.) > > -GAWollman > > _______________________________________________ > freebsd-security at freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-security > To unsubscribe, send any mail to "freebsd-security-unsubscribe at freebsd.org > " >-- Mike Kelly
On Fri, 9 Sep 2016, Garrett Wollman wrote:> Presently, we have a bunch of machines under configuration management > (using Puppet, but that's not really relevant here). I'm hoping to > implement LDAP via nsswitch on these machines, but I've run into an > issue: the standard getpw*(3) mechanisms can't tell the difference > between users or groups in the local databases and those in the remote > LDAP database. We need Puppet to manage entries for users and groups > in the local database, without respect to what entries might be > imported from LDAP (because they are supposed to override the data > returned by LDAP). Puppet invokes pw(8) to actually perform the > modifications, but I suspect it also uses native code from the Ruby > standard library to actually do pre-modification lookups. > > Looking at the code in both nss-pam-ldapd and libc, it seems like the > only plausible way to fix this is to add functionality to nsswitch > which would allow it to use different configurations depending on the > identity of the process invoking getpwnam(3) or getgrnam(3). Does > anyone have opinions on how this ought to be implemented, or indeed > how it could be implemented securely?It's a bit late here, but it sounds kind of like you want to be able to set NSS_NONLOCAL_IGNORE [and have it do something useful]? (https://debathena.mit.edu/nss_nonlocal/) Unfortunately, I never got far enough in trying to port Athena to FreeBSD to have looked at how portable nss_nonlocal is. But it is probably worth looking at, for your case. -Ben
Hi, We have system images under version control with password databases as part of the system image which get merged with system-specific password databases. Not exactly the same requirement but similar. We manage the two separate databases using the -V option to pw, and then have a script to merge the two databases into the standard local database. This runs on boot to bring in changes from the system image build, and after a local system change to apply the change. The problem with your environment is probably that you?re calling getpwnam, etc., where you can?t specify which password database you want to use. If you changed the code that should only view local changes to use ?pw -V /path/to/local usershow? instead of calling getpw*(), a similar approach might be possible. Regards, Jan.> On 10 Sep 2016, at 06:04, Garrett Wollman <wollman at bimajority.org> wrote: > > Presently, we have a bunch of machines under configuration management > (using Puppet, but that's not really relevant here). I'm hoping to > implement LDAP via nsswitch on these machines, but I've run into an > issue: the standard getpw*(3) mechanisms can't tell the difference > between users or groups in the local databases and those in the remote > LDAP database. We need Puppet to manage entries for users and groups > in the local database, without respect to what entries might be > imported from LDAP (because they are supposed to override the data > returned by LDAP). Puppet invokes pw(8) to actually perform the > modifications, but I suspect it also uses native code from the Ruby > standard library to actually do pre-modification lookups. > > Looking at the code in both nss-pam-ldapd and libc, it seems like the > only plausible way to fix this is to add functionality to nsswitch > which would allow it to use different configurations depending on the > identity of the process invoking getpwnam(3) or getgrnam(3). Does > anyone have opinions on how this ought to be implemented, or indeed > how it could be implemented securely? > > (As a side issue, the net/nss-pam-ldapd port completely ignores > account expiration dates. This bug is due to the fact that Linux has > this ships-in-the-night "shadow" mechanism, getspent(3), rather than > having it integrated in getpwent(3) like it should be, but the > ultimate upshot is that if you're using nss-pam-ldapd you can't rely > on shadowExpire attributes in the directory actually have an effect on > FreeBSD. I'll open a bugzilla issue about this.) > > -GAWollman > > _______________________________________________ > freebsd-arch at freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-arch > To unsubscribe, send any mail to "freebsd-arch-unsubscribe at freebsd.org"