On 08/22/2016 16:11, Bryan Drewery wrote: > On 8/22/2016 1:01 PM, Eric van Gyzen wrote: >> I had never looked at pam_ssh before. Does it really ignore authorized_keys >> and > > Yeah, that was the entire purpose! > https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=15158
Ah, thanks for that research. > For its original purpose I can understand using it, to login *locally*... Yeah, pam_ssh makes sense for local logins, but even then I still find it alarming that it looks at all default key file names. If I change pam_ssh to only use authorized_keys, I would be adding the assumption that users authenticate with the same keys over ssh as on the console. The current pam_ssh code allows different keys (viz. authorized_keys versus id_foo). This seems like a perfectly reasonable assumption. I'd like to hear whether this would break anyone's deployment of pam_ssh. If so, I'd also like to hear a strong argument for such a use case. I might have to ask on, say, questions@ to get a wider audience. > I am surprised to find this too. Thanks for confirming my remaining sanity. :) > At least it is off-by-default: Indeed. > The manpage has this gem: > "nullok Normally, keys with no passphrase are ignored for > authentication purposes. If this option is set, keys with no passphrase > will be taken into consideration, allowing the user to log in with a > blank password." > > Why would anyone ever use nullok and use the pam_ssh module? I don't > know pam well but I'm sure there's another way to make a check always > succeed without a password. So supporting nullok in pam_ssh is just > asking for an unknown security bug. Yes, I also don't like nullok here. There are use cases for a private key without a password, but this is not one of them. > Why is it even in the remote service files as an example when it is > dangerous in those contexts? Good point. I'll remove it from the dangerous examples (unless you beat me to it, since it's time for supper). ;) Eric _______________________________________________ freebsd-security@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-security To unsubscribe, send any mail to "freebsd-security-unsubscr...@freebsd.org"
