Jan Cholasta <jcholast(a)redhat.com> wrote:
Updated patches attached.
Dne 6.2.2012 23:13, Jakub Hrozek napsal(a):
> On Mon, Feb 06, 2012 at 07:48:10PM +0100, Jakub Hrozek wrote:
>> On Mon, Feb 06, 2012 at 05:42:15PM +0100, Jan Cholasta wrote:
>>> Updated& rebased the patches on top of current master.
>>>
>>> To test them, install a SSH-patched (see freeipa-devel) FreeIPA
>>> server, set host public keys using "ipa host-mod" (actually this
>>> should be done automatically when the IPA server/client is
>>> installed) and set user public keys using "ipa user-mod".
>>>
>>> Configure sshd (the SSH server) by putting this line in
>>>
>>> /etc/ssh/sshd_config:
>>> AuthorizedKeysCommand /usr/bin/sss_ssh_authorizedkeys
>>>
>>> or, if you test on RHEL, this line:
>>> PubkeyAgent /usr/bin/sss_ssh_authorizedkeys %u
>>>
>>> Configure ssh (the SSH client) by putting these lines in .ssh/config:
>>> ProxyCommand /usr/bin/sss_ssh_knownhostsproxy -p %p %h
>>> UserKnownHostsFile2 .ssh/sss_known_hosts
>>>
>>> Make sure that the server host key is not present in
>>> .ssh/known_hosts before testing.
>>>
>>> You should then be able to log in to the server using the user
>>> public key stored in IPA (ssh should not attempt to use password
>>> authentication). To verify that the host keys have been fetched, see
>>> whether .ssh/sss_known_hosts was created.
>>>
>>>
>>> [PATCH 1/10] UTIL: Provide base64 encoding and decoding functions
>>
>> Ack
>>
>>> [PATCH 2/10] BUILD: Introduce a --with-ssh config option
>>
>> Ack
>>
>>> [PATCH 3/10] LDAP: Add support for SSH user public keys
>>
>> I really don't like special-casing SYSDB_SSH_PUBKEY in
>> sdap_parse_entry(). However, I'm not sure how to handle this in a way
>> that both nice and is not a huge change.
>>
>> Maybe we could leave this as-is for 1.8beta and file a ticket (a blocker
>> or something that would be red and flashing) to improve later.
>>
>> There's two options I can think of:
>> 1) the encoding is currently only needed for hosts and users. We could
>> extend sdap_save_users to base64 encode this attribute and then create a
>> wrapper for saving hosts for use in ipa_hostid.c
>> 2) we could make this a little more generic and add a special callback
>> to the attribute map that would allow munging attributes when we receive
>> them from LDAP.
>>
>>> [PATCH 4/10] DP: Add host info handler
>>
>> Add the hostid_provider to the configAPI tests, otherwise make check
>> won't work.
>>
>> The BE_REQ_AUTOFS hunk is an important one and should maybe be split
>> into a separate patch (it *definitely* needs to go into 1.8beta, it is
>> a bad merge of autofs on top of sudo).
>>
>>> [PATCH 5/10] IPA: Add host info handler
>>
>> sysdb_ssh_host_dn() does not appear to be used anywhere and can be
>> removed.
>>
>> I'll review the rest when I'm finished with my patches currently on the
>> list.
>
> ipa_host_info_handler(): please put ret = EOK above the "done:" label.
> The code is OK now but if we added some check that would return != EOK
> we might be in trouble.
>
> hosts_get_done(): the delete and save should be done in a single
> transaction. Check out services or autofs code for an example of code
> that tracks if it's inside transaction and commits or cancels if
> appropriate.
>
> ipa_host_info_recv() can return multiple hosts (and only a single one is
> deleted in the code afterwards), but you are saving multiple hosts in a
> loop. If only one host is expected, put a check for count == 1,
> otherwise error out and save only hosts[0].
>
> ipa_hostid is included only conditionally in Makefile.am, but ipa_init.c
> references ipa_host_info_handler unconditionally. This would cause a
> runtime error if IPA provider was built --without-ssh (Been there, done
> that with the sudo provider..) I ended up putting all the conditional
> code into the file that is compiled conditionally, kept as little entry
> points from the generic part of code (such as sssm_ipa_hostid_init()).
>
>>> [PATCH 6/10] DP: Add support for hosts in sss_dp_get_account
>
> This is good enough for the beta, but I think we shouldn't misuse
> dp_get_account_send() for data that is not name-service-switch. I think
> that creating a dp_get_host_send() would be cleaner (even if duplicating
> some code).
>
> Please file a ticket on this, we can just close it should we decide to
> keep using dp_get_account_send().
>
>>> [PATCH 7/10] SSH: Responder
>
> ssh_cmd_parse_request():
> You need to check that the names that are coming in from the client are
> valid UTF-8 (I just noticed that sudo does not do that either and filed
> a ticket).
>
> Have you tested what name do you receive when the domain is case
> insensitive? This should be also tested post-beta.
>
>>> [PATCH 8/10] SSH: Common client code
>
> Ack
>
>>> [PATCH 9/10] SSH: OpenSSH authorized_keys client
>
> You call getpwuid() but the DEBUG message says getpwnam.
>
> Otherwise ack.
>
>>> [PATCH 10/10] SSH: OpenSSH known_hosts client
>
> Please file a ticket to handle concurrent writes of the sss_known_hosts
> file.
>
> If an operation fails in run_connect(), don't forget to close the
> socket.
>
> Otherwise ack.
>
> After this is pushed, check if everything works with SELinux in
> enforcing mode and file a bug against selinux-policy if it does not.
>
>>> Dne 6.2.2012 14:39, Jan Zelený napsal(a):
>>>>> It seems that the patches depend on Jan's SELinux patches or at
least
>>>>> the IPA host patch. I think you should just rebase your patches on
>>>>> top of his, even though we usually say that patches should apply on
>>>>> master.
>>>>>
>>>>> On Sat, Feb 04, 2012 at 11:43:56AM +0100, Jan Cholasta wrote:
>>>>>> Dne 4.2.2012 11:05, Jakub Hrozek napsal(a):
>>>>>>> On Fri, Feb 03, 2012 at 11:29:52PM +0100, Jan Cholasta
wrote:
>>>>>>>> Hi,
>>>>>>>>
>>>>>>>> this is a set of patches implementing SSH support in
SSSD.
>>>>>>>>
>>>>>>>> To test it, install a SSH-patched (patches are on
freeipa-devel)
>>>>>>>> IPA server, create a test user with SSH public keys
("ipa
>>>>>>>> user-add someuser --sshpubkey=<blob>"), and
then use the
>>>>>>>> sss_ssh_authorizedkeys command to get the user's SSH
public keys
>>>>>>>> ("sss_ssh_authorizedkeys someuser" should
output user's public
>>>>>>>> keys in OpenSSH's authorized_keys format).
>>>>>>>
>>>>>>> Is there a way to test these using an actual SSH client
yet?
>>>>>>
>>>>>> Set AuthorizedKeysCommand option in your sshd_config to
>>>>>> "<path>/sss_ssh_authorizedkeys".
>>>>>>
>>>>>>>> This is not a complete set of patches for SSH support,
some work
>>>>>>>> is still missing and will be posted soon (SSH host keys
support
>>>>>>>> in IPA provider, known_hosts client and documentation).
>>>>>>>
>>>>>>> Also please remember to add the new options to the
ConfigAPI.
>>>>>>
>>>>>> OK, will do.
>>>>>>
>>>>>>>> [PATCH 1/9] UTIL: Provide base64 encoding and decoding
functions
>>>>>>>
>>>>>>> Can you add a DEBUG() message saying that
>>>>>>> sss_base64_{encode,decode} are not implemented with
libcrypto back
>>>>>>> end?
>>>>>>
>>>>>> Sure.
>>>>>>
>>>>>>> I think the NSS back end sss_base64_{encode,decode} should
call
>>>>>>> nspr_nss_init() otherwise they are just relying on the NSS
crypto
>>>>>>> library being initialized.
>>>>>>
>>>>>> OK.
>>>>>>
>>>>>>>> [PATCH 2/9] BUILD: Introduce a --with-ssh config option
>>>>>>>
>>>>>>> ACK to the code, but this patch will likely need a rebase on
top of
>>>>>>> the similar sudo/autofs patches.
>>>>>>
>>>>>> Yes, I expect that.
>>>>>
>>>>> Please note that there was a bug in the sudo patch this --with-ssh
>>>>> patch is based on. You need to either remove the "[]" that
is the
>>>>> "action-not-found" parameter or put a comma after it,
otherwise
>>>>> configure would error out on RHEL5.
>>>>>
>>>>>>>> [PATCH 3/9] LDAP: Add support for SSH user public keys
>>>>>>>
>>>>>>> This patch should be rebased on top of Stephen's cache
timeout
>>>>>>> patch that is already acked on the list.
>>>>>>
>>>>>> OK.
>>>>>>
>>>>>>> I don'really like the "continue" special case
in sdap_save_user().
>>>>>>> Why not simply move SDAP_AT_USER_SSH_PUBLIC_KEY before
>>>>>>> SDAP_FIRST_EXTRA_USER_AT?
>>>>>>
>>>>>> I guess I didn't want to add new attributes in the middle of
the
>>>>>> user map. I can easily change that.
>>>>
>>>> I agree with Jakub here, please move it :-)
>>>
>>> Fixed, though in a different fashion.
>>>
>>>>>>>> [PATCH 4/9] DP: Add auxiliary info handler
>>>>>>>> This is used to handle non-NSS accounts, such as hosts.
>>>>
>>>> Please change all DEBUG levels from numeric to the new declarations
>>>
>>> Done.
>>>
>>>>>>>> [PATCH 5/9] IPA: Add auxiliary info handler
>>>>>>>
>>>>>>> I'm not a big fan of the auxilary handler, to be honest.
While it
>>>>>>> saves a lot of code duplication, how do you define what
falls into
>>>>>>> the auxiliary category and what needs its own provider
type?
>>>>>>
>>>>>> I can see you concern. Would it be OK to make a handler just
for
>>>>>> host info then?
>>>>>
>>>>> This is more of an architectural decision, so I'd like to hear
>>>>> another opinions here.
>>>>
>>>> I don't like the "auxiliary" solution either. It seems to
be halfway
>>>> solution between extending ID handler and making something like
"host
>>>> target" only for information about hosts.
>>>>
>>>>> I personally think that adding a special handler just for host info
>>>>> is better mostly because it would allow to have a different
provider
>>>>> for hosts and for identities for example. Cluttering the
>>>>> configuration is not a big problem because in most cases, the
>>>>> additional data providers (except for auth and chpass) can just
>>>>> inherit the id_provider value.
>>>>
>>>> Is there a plan for fetching some more information about the host? If
>>>> yes, then I agree that is should have its own target. If not, I like
>>>> the extension of current ID handler better because of the code
>>>> duplication reduction.
>>>
>>> I have changed the auxiliary info handler to host(-only) info handler.
>>>
>>> Also, I have added some sysdb-related code to patch 5.
>>>
>>>>> I see the point of code duplication, too. Could it be solved with
>>>>> code refactoring to add some more generic functions?
>>>>>
>>>>>>> The rest is TBR, I'll continue later.
>>>>>>
>>>>>> Thanks.
>>>>
>>>> Please change all DEBUG levels from numeric to the new declarations.
>>>
>>> Done.
>>>
>>>>>>>> [PATCH 6/9] DP: Add support for hosts in
sss_dp_get_account
>>>>>>>> Host requests are directed to the auxiliary info
handler.
>>>>>
>>>>> This patch is fine provided that we decide to go forward with the
>>>>> auxiliary info handler.
>>>
>>> Changed the patch to use the host handler.
>>>
>>>>>>>> [PATCH 7/9] SSH: Responder
>>>>>
>>>>> The provider does not work offline. There needs to be a fallback
case
>>>>> that returns cached data in case the provider can't contact DP.
If
>>>>> you think we absolutely need to contact DP every login, you can add
>>>>> some "cache_authorized_keys" option that would default to
false.
>>>
>>> Fixed.
>>>
>>>>> Do you consider adding any form of cache, either negative or
>>>>> positive? I see the concern of having the keys always accurate, but
>>>>> for fast successive logins, maybe at least short lived in-memory
>>>>> cache would provide better performance.
>>>
>>> This is planned.
>>>
>>>>> The while(dom) loops in both of the _search() functions are not
>>>>> needed for this type of responder that always goes to DP. If there
>>>>> are no plans for a cache, then you can simply call
>>>>> sss_dp_get_account_send() in the _search() function. Then in the
>>>>> callback, either advance to the next domain if there are no results
>>>>> (with the optional cache fallback) or process the results. This is
>>>>> just a refactoring though, it can be done later during 1.8
>>>>
>>>> I agree with this. I didn't do deep review since a lot of code is
>>>> probably going to be changed here. I'll wait for the second round
:)
>>>
>>> Removed the loop.
>>>
>>>> I'm not sure why are you creating the response packet outside of
the
>>>> ssh_cmd_build_reply() function. I think it would be better there.
>>>
>>> Fixed.
>>>
>>>> Also, change all DEBUG levels from numeric to the new declarations.
>>>> There is one left I think.
>>>
>>> Done.
>>>
>>>>>>>> [PATCH 8/9] SSH: Common client code
>>>>>
>>>>> sss_ssh_get_pubkeys(): Please allocate tmp_ctx on NULL and only
steal
>>>>> the return values to mem_ctx.
>>>
>>> Done.
>>>
>>>> I agree. In fact, I would prefer not to use talloc at all since the
>>>> client will be fully synchronous. This argument will be especially
>>>> valid if you want this common code to be reused in other client
>>>> programs.
>>>
>>> I see no harm in using talloc, even if the clients are fully
>>> synchronous. Currently there are no other SSH client programs
>>> planned.
>>>
>>>> The other thing is about keys getting decoded from base64 in the
>>>> responder and then encoded again in the client, but I guess that's
a
>>>> design decision and I'll respect that even though I find it
>>>> redundant.
>>>
>>> It doesn't seem right to me to transport the keys base64-encoded.
>>> The code can be easily changed, though.
>>>
>>>>> Otherwise looks good to me.
>>>>>
>>>>>>>> [PATCH 9/9] SSH: AuthorizedKeysCommand client
>>>>>
>>>>> It is not clear if this is the commands that SSH is supposed to be
>>>>> using or just a test binary -- it is in noinst_PROGRAMs in
>>>>> Makefile.am and not packaged in the RPMs.
>>>
>>> That was just a temporary thing. The client programs are supposed to
>>> be run from ssh/sshd. It should be clearer now that man pages are
>>> included.
>>>
>>>>> In case it is actually supposed to be used by SSH:
>>>>> Are the return values arbitratily picked or does SSH expect any of
>>>>> them?
>>>>>
>>>>> Can any of the error messages be returned to the user or does SSH
>>>>> mostly use the binary as a "libexec" ? If the messages can
be
>>>>> returned to the user, they should be marked as translatable (see
the
>>>>> "ERROR()" macro).
>>>
>>> Fixed (anything from stderr is displayed to the user).
Ack for all patches,
there are couple things left though. After consulting them with Honza, I
decided that they can be fixed later. I'll file a ticket for them first thing
tomorrow.
Thanks
Jan