[Samba] Fwd: PAM Offline Authentication in Ubuntu 22.04...

Kees van Vloten keesvanvloten at gmail.com
Sat Jun 3 18:12:51 UTC 2023


On 03-06-2023 16:57, Rowland Penny via samba wrote:
>
>
> On 03/06/2023 12:27, Kees van Vloten via samba wrote:
>>
>> However for a lookup with the command 'id' pam_winbind is irrelevant 
>> since we only do a user and group lookup, it is nss-winbind that is 
>> being used.
>>
>> I don't see any differences between our smb.conf file that could 
>> cause this issue, do you?
>>
>> I guess the next thing to try is increase log level to a high value 
>> and repeat the test, any other ideas?
>>
>> - Kees.
>
> When you logon it is pam_winbind that is used, from my tests there is 
> just one line different in /var/log/auth.log between having the 
> network connected or not at logon
> Without the network, I get this extra line:
>
> May 28 08:20:59 member1 lightdm: pam_winbind(lightdm:auth): User 
> rowland logged on using cached credentials
>
> If you use gdm3, you get a similar line.
I understand that, however the test with 'id testuser' does not do 
authentication. SInce it already reproduces the issue that rules out any 
issues with pam_winbind. Therefore it must be an issue in nss_winbind.
>
> By all means try a higher log level, but my gut feeling is that it is 
> something at the OS level that is creating the wait.
>
> Rowland
>
>
I ran both connected and disconnected 'id testuser' through strace and 
in smb.conf: "log level 3 winbind:10"

The first 200 lines are left away since they are equal in both situation.

strace id testuser connected:

mprotect(0x7fa1cf90f000, 4096, PROT_READ) = 0
mprotect(0x7fa1cf925000, 4096, PROT_READ) = 0
mprotect(0x7fa1cf939000, 4096, PROT_READ) = 0
munmap(0x7fa1cff3d000, 122599)          = 0
getpid()                                = 1961
getpid()                                = 1961
getpid()                                = 1961
futex(0x7fa1cfca20c8, FUTEX_WAKE_PRIVATE, 2147483647) = 0
lstat("/run/samba/winbindd", {st_mode=S_IFDIR|0755, st_size=60, ...}) = 0
lstat("/run/samba/winbindd/pipe", {st_mode=S_IFSOCK|0777, st_size=0, 
...}) = 0
socket(AF_UNIX, SOCK_STREAM, 0)         = 3
fcntl(3, F_GETFL)                       = 0x2 (flags O_RDWR)
fcntl(3, F_SETFL, O_RDWR|O_NONBLOCK)    = 0
fcntl(3, F_GETFD)                       = 0
fcntl(3, F_SETFD, FD_CLOEXEC)           = 0
connect(3, {sa_family=AF_UNIX, sun_path="/run/samba/winbindd/pipe"}, 
110) = 0
getpid()                                = 1961
getpid()                                = 1961
poll([{fd=3, events=POLLIN|POLLOUT|POLLHUP}], 1, -1) = 1 ([{fd=3, 
revents=POLLOUT}])
write(3, 
"X\10\0\0\0\0\0\0\0\0\0\0\251\7\0\0\0\10\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 
2136) = 2136
getpid()                                = 1961
poll([{fd=3, events=POLLIN|POLLHUP}], 1, 5000) = 1 ([{fd=3, 
revents=POLLIN}])
read(3, "\250\17\0\0\2\0\0\0 
\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 4008) = 4008
poll([{fd=3, events=POLLIN|POLLOUT|POLLHUP}], 1, -1) = 1 ([{fd=3, 
revents=POLLOUT}])
write(3, 
"X\10\0\0\1\0\0\0\0\0\0\0\251\7\0\0\0\0\2\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 
2136) = 2136
getpid()                                = 1961
poll([{fd=3, events=POLLIN|POLLHUP}], 1, 5000) = 1 ([{fd=3, 
revents=POLLIN}])
read(3, 
"\250\17\0\0\2\0\0\0kvv\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 
4008) = 4008
openat(AT_FDCWD, "/etc/passwd", O_RDONLY|O_CLOEXEC) = 4
lseek(4, 0, SEEK_CUR)                   = 0
fstat(4, {st_mode=S_IFREG|0644, st_size=2475, ...}) = 0
read(4, "root:x:0:0:root:/root:/bin/bash\n"..., 4096) = 2475

strace -tt id testuser disconnected and ctrl-c where it "hangs":

19:42:47.526437 mprotect(0x7ff2bc581000, 4096, PROT_READ) = 0
19:42:47.526499 mprotect(0x7ff2bc597000, 4096, PROT_READ) = 0
19:42:47.526548 mprotect(0x7ff2bc5ab000, 4096, PROT_READ) = 0
19:42:47.526594 munmap(0x7ff2bcbaf000, 122599) = 0
19:42:47.526660 getpid()                = 3979
19:42:47.526699 getpid()                = 3979
19:42:47.526733 getpid()                = 3979
19:42:47.526771 futex(0x7ff2bc9140c8, FUTEX_WAKE_PRIVATE, 2147483647) = 0
19:42:47.526856 lstat("/run/samba/winbindd", {st_mode=S_IFDIR|0755, 
st_size=60, ...}) = 0
19:42:47.526928 lstat("/run/samba/winbindd/pipe", 
{st_mode=S_IFSOCK|0777, st_size=0, ...}) = 0
19:42:47.526970 socket(AF_UNIX, SOCK_STREAM, 0) = 3
19:42:47.527007 fcntl(3, F_GETFL)       = 0x2 (flags O_RDWR)
19:42:47.527062 fcntl(3, F_SETFL, O_RDWR|O_NONBLOCK) = 0
19:42:47.527127 fcntl(3, F_GETFD)       = 0
19:42:47.527174 fcntl(3, F_SETFD, FD_CLOEXEC) = 0
19:42:47.527210 connect(3, {sa_family=AF_UNIX, 
sun_path="/run/samba/winbindd/pipe"}, 110) = 0
19:42:47.527396 getpid()                = 3979
19:42:47.527502 getpid()                = 3979
19:42:47.527553 poll([{fd=3, events=POLLIN|POLLOUT|POLLHUP}], 1, -1) = 1 
([{fd=3, revents=POLLOUT}])
19:42:47.527653 write(3, 
"X\10\0\0\0\0\0\0\0\0\0\0\213\17\0\0\0\10\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 
2136) = 2136
19:42:47.527817 getpid()                = 3979
19:42:47.527852 poll([{fd=3, events=POLLIN|POLLHUP}], 1, 5000) = 1 
([{fd=3, revents=POLLIN}])
19:42:47.527895 read(3, "\250\17\0\0\2\0\0\0 
\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 4008) = 4008
19:42:47.527938 poll([{fd=3, events=POLLIN|POLLOUT|POLLHUP}], 1, -1) = 1 
([{fd=3, revents=POLLOUT}])
19:42:47.527979 write(3, 
"X\10\0\0\1\0\0\0\0\0\0\0\213\17\0\0\0\0\2\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 
2136) = 2136
19:42:47.528428 getpid()                = 3979
19:42:47.528465 poll([{fd=3, events=POLLIN|POLLHUP}], 1, 5000) = 0 (Timeout)
19:42:52.531442 poll([{fd=3, events=POLLIN|POLLHUP}], 1, 5000) = 0 (Timeout)
19:42:57.537318 poll([{fd=3, events=POLLIN|POLLHUP}], 1, 5000) = 0 (Timeout)
19:43:02.544018 poll([{fd=3, events=POLLIN|POLLHUP}], 1, 5000) = ? 
ERESTART_RESTARTBLOCK (Interrupted by signal)
19:43:02.711306 --- SIGINT {si_signo=SIGINT, si_code=SI_KERNEL} ---
19:43:02.711867 +++ killed by SIGINT +++

log.wb-SAMDOM show the domain is reported offline before "id testuser" 
is started

[2023/06/03 19:40:06.824113,  0, pid=2926, effective(0, 0), real(0, 0), 
class=winbind] 
../../source3/winbindd/winbindd_cache.c:3464(set_global_winbindd_state_offline)
   set_global_winbindd_state_offline: Offline requested
[2023/06/03 19:40:06.824140, 10, pid=2926, effective(0, 0), real(0, 0), 
class=winbind] ../../source3/winbindd/winbindd_cm.c:163(set_domain_offline)
   set_domain_offline: called for domain SAMDOM
[2023/06/03 19:40:06.824175, 10, pid=2926, effective(0, 0), real(0, 0), 
class=winbind] ../../source3/winbindd/winbindd_cm.c:163(set_domain_offline)
   set_domain_offline: called for domain SAMDOM
[2023/06/03 19:40:06.824205, 10, pid=2926, effective(0, 0), real(0, 0), 
class=winbind] 
../../source3/winbindd/winbindd_cache.c:1794(wcache_name_to_sid)
   wcache_name_to_sid: namemap_cache_find_name failed
[2023/06/03 19:40:06.824216,  4, pid=2926, effective(0, 0), real(0, 0), 
class=winbind] ../../source3/winbindd/winbindd_dual.c:1641(child_handler)
   Finished processing child request 55
[2023/06/03 19:40:06.824222, 10, pid=2926, effective(0, 0), real(0, 0), 
class=winbind] 
../../source3/winbindd/winbindd_dual.c:159(child_write_response)
   Writing 4024 bytes to parent
[2023/06/03 19:42:37.973329, 10, pid=2926, effective(0, 0), real(0, 0), 
class=winbind] 
../../source3/winbindd/winbindd_cm.c:3284(winbind_msg_ip_dropped)
   IP 192.168.1.108 dropped
[2023/06/03 19:42:37.973344, 10, pid=2926, effective(0, 0), real(0, 0), 
class=winbind] 
../../source3/winbindd/winbindd_cm.c:3284(winbind_msg_ip_dropped)
   IP fe80::3f67:f5b0:e1ca:720d dropped

log.winbindd-idmap:

[2023/06/03 19:42:47.528286, 10, pid=2782, effective(0, 0), real(0, 0), 
class=winbind] 
../../source3/winbindd/winbindd_dual.c:124(child_read_request)
   Need to read 214 extra bytes
[2023/06/03 19:42:47.528301,  4, pid=2782, effective(0, 0), real(0, 0), 
class=winbind] ../../source3/winbindd/winbindd_dual.c:1633(child_handler)
   child daemon request 55
[2023/06/03 19:42:47.528307, 10, pid=2782, effective(0, 0), real(0, 0), 
class=winbind] 
../../source3/winbindd/winbindd_dual_ndr.c:538(winbindd_dual_ndrcmd)
   winbindd_dual_ndrcmd: Running command wbint_GetNssInfo (domain '(null)')
[2023/06/03 19:42:47.528338, 10, pid=2782, effective(0, 0), real(0, 0), 
class=winbind] ../../source3/winbindd/idmap_ad.c:532(idmap_ad_query_user)
   idmap_ad_query_user: Filter: 
[(objectsid=\01\05\00\00\00\00\00\05\15\00\00\00\FB'\BF\F9.lc\D8\C5\CF]y\CD\04\00\00)]
[2023/06/03 19:42:47.528357, 10, pid=2782, effective(0, 0), real(0, 0), 
class=winbind] ../../source3/winbindd/idmap_ad.c:289(idmap_ad_tldap_debug)
   idmap_ad_tldap: tldap_msg_send: sending msg 29
============ THIS IS WHERE THE TIMEOUT IN STRACE HAPPENS ============

log.winbindd

[2023/06/03 19:42:47.528012,  3, pid=2759, effective(0, 0), real(0, 0), 
class=winbind] ../../source3/winbindd/winbindd.c:496(process_request_send)
   process_request_send: [nss_winbind (3979)] Handling async request: 
GETPWNAM
[2023/06/03 19:42:47.528022,  3, pid=2759, effective(0, 0), real(0, 0), 
class=winbind] 
../../source3/winbindd/winbindd_getpwnam.c:59(winbindd_getpwnam_send)
   [nss_winbind (3979)] Winbind external command GETPWNAM start.
   Query username 'testuser'.
[2023/06/03 19:42:47.528032,  5, pid=2759, effective(0, 0), real(0, 0), 
class=winbind] ../../source3/winbindd/wb_lookupname.c:52(wb_lookupname_send)
   WB command lookupname start.
   Search namespace 'SAMDOM' and domain 'SAMDOM' for name 'testuser'.
[2023/06/03 19:42:47.528062, 10, pid=2759, effective(0, 0), real(0, 0), 
class=winbind] 
../../source3/winbindd/winbindd_dual_ndr.c:112(wbint_bh_raw_call_send)
   wbint_bh_raw_call_send: Got opnum 3 for domain SAMDOM from cache
[2023/06/03 19:42:47.528077,  5, pid=2759, effective(0, 0), real(0, 0), 
class=winbind] 
../../source3/winbindd/wb_lookupname.c:118(wb_lookupname_recv)
   WB command lookupname end.
   Found SID S-1-5-21-4190054395-3630394414-2036191173-1229 with SID type 1.
[2023/06/03 19:42:47.528088,  5, pid=2759, effective(0, 0), real(0, 0), 
class=winbind] ../../source3/winbindd/wb_getpwsid.c:49(wb_getpwsid_send)
   WB command getpwsid start.
   Query user SID S-1-5-21-4190054395-3630394414-2036191173-1229.
[2023/06/03 19:42:47.528096,  5, pid=2759, effective(0, 0), real(0, 0), 
class=winbind] ../../source3/winbindd/wb_queryuser.c:56(wb_queryuser_send)
   WB command queryuser start.
   Query user sid S-1-5-21-4190054395-3630394414-2036191173-1229
[2023/06/03 19:42:47.528107, 10, pid=2759, effective(0, 0), real(0, 0), 
class=winbind] 
../../source3/winbindd/wb_queryuser.c:95(wb_queryuser_idmap_setup_done)
   Convert the user SID S-1-5-21-4190054395-3630394414-2036191173-1229 
to XID.
[2023/06/03 19:42:47.528113,  5, pid=2759, effective(0, 0), real(0, 0), 
class=winbind] ../../source3/winbindd/wb_sids2xids.c:84(wb_sids2xids_send)
   WB command sids2xids start.
   Resolving 1 SID(s).
[2023/06/03 19:42:47.528120, 10, pid=2759, effective(0, 0), real(0, 0), 
class=winbind] ../../source3/winbindd/wb_sids2xids.c:156(wb_sids2xids_send)
   0: SID S-1-5-21-4190054395-3630394414-2036191173-1229
[2023/06/03 19:42:47.528141, 10, pid=2759, effective(0, 0), real(0, 0), 
class=winbind] ../../source3/winbindd/wb_sids2xids.c:175(wb_sids2xids_send)
   Found 1 (out of 1) SID(s) in cache.
[2023/06/03 19:42:47.528152,  5, pid=2759, effective(0, 0), real(0, 0), 
class=winbind] ../../source3/winbindd/wb_sids2xids.c:775(wb_sids2xids_recv)
   WB command sids2xids end.
[2023/06/03 19:42:47.528157,  5, pid=2759, effective(0, 0), real(0, 0), 
class=winbind] ../../source3/winbindd/wb_sids2xids.c:779(wb_sids2xids_recv)
   0: Found XID 1104 for SID S-1-5-21-4190054395-3630394414-2036191173-1229
[2023/06/03 19:42:47.528163, 10, pid=2759, effective(0, 0), real(0, 0), 
class=winbind] 
../../source3/winbindd/wb_queryuser.c:134(wb_queryuser_got_uid)
   Received XID 1104 for SID S-1-5-21-4190054395-3630394414-2036191173-1229.
[2023/06/03 19:42:47.528169, 10, pid=2759, effective(0, 0), real(0, 0), 
class=winbind] 
../../source3/winbindd/wb_queryuser.c:148(wb_queryuser_got_uid)
[2023/06/03 19:42:47.528169, 10, pid=2759, effective(0, 0), real(0, 0), 
class=winbind] 
../../source3/winbindd/wb_queryuser.c:148(wb_queryuser_got_uid)
   Preconfigured 'Domain Users' RID 513 was used to create group SID 
S-1-5-21-4190054395-3630394414-2036191173-513 from user SID 
S-1-5-21-4190054395-3630394414-2036191173-1229.
[2023/06/03 19:42:47.528176, 10, pid=2759, effective(0, 0), real(0, 0), 
class=winbind] 
../../source3/winbindd/wb_queryuser.c:154(wb_queryuser_got_uid)
   Setting 'homedir' to the template '/home/%U'.
[2023/06/03 19:42:47.528181, 10, pid=2759, effective(0, 0), real(0, 0), 
class=winbind] 
../../source3/winbindd/wb_queryuser.c:160(wb_queryuser_got_uid)
   Setting 'shell' to the template '/bin/bash'.
[2023/06/03 19:42:47.528206, 10, pid=2759, effective(0, 0), real(0, 0), 
class=winbind] 
../../source3/winbindd/wb_queryuser.c:167(wb_queryuser_got_uid)
   Filling data received from netsamlogon_cache
       state->info: struct wbint_userinfo
           domain_name              : *
               domain_name              : 'SAMDOM'
           acct_name                : *
               acct_name                : 'testuser'
           full_name                : *
               full_name                : 'Test User'
           homedir                  : *
               homedir                  : '/home/%U'
           shell                    : *
               shell                    : '/bin/bash'
           uid                      : 0x00000000000003ec (1104)
           primary_gid              : 0x00000000ffffffff (4294967295)
           primary_group_name       : NULL
           user_sid                 : 
S-1-5-21-4190054395-3630394414-2036191173-1229
           group_sid                : 
S-1-5-21-4190054395-3630394414-2036191173-513
[2023/06/03 19:42:47.528248, 10, pid=2759, effective(0, 0), real(0, 0), 
class=winbind] 
../../source3/winbindd/wb_queryuser.c:198(wb_queryuser_got_uid)
   Domain name is set, calling dcerpc_wbint_GetNssInfo_send()
============ THIS IS WHERE THE TIMEOUT IN STRACE HAPPENS ============
[2023/06/03 19:42:56.059505, 10, pid=2759, effective(0, 0), real(0, 0), 
class=winbind] 
../../source3/winbindd/winbindd_util.c:715(winbindd_ping_offline_domains)
   winbindd_ping_offline_domains: Domain BUILTIN is online
[2023/06/03 19:42:56.059550, 10, pid=2759, effective(0, 0), real(0, 0), 
class=winbind] 
../../source3/winbindd/winbindd_util.c:720(winbindd_ping_offline_domains)
   winbindd_ping_offline_domains: We are globally offline, do nothing.
[2023/06/03 19:43:02.711750,  6, pid=2759, effective(0, 0), real(0, 0), 
class=winbind] 
../../source3/winbindd/winbindd.c:772(winbind_client_activity)
   winbind_client_activity[3979:GETPWNAM]: client has closed connection 
- removing client
[2023/06/03 19:43:02.711803,  2, pid=2759, effective(0, 0), real(0, 0), 
class=winbind] ../../source3/winbindd/winbindd.c:884(remove_client)
   final write to client failed: Broken pipe
[2023/06/03 19:43:02.711839,  1, pid=2759, effective(0, 0), real(0, 0), 
class=winbind] 
../../source3/winbindd/winbindd_dual.c:370(wb_child_request_cleanup)
   wb_child_request_cleanup: keep orphaned subreq[0x559ec34dd000]

Unfortunately I don't see a clear correlation between the strace output 
and an event in the logging. I guess I have to run a strace on the 
winbindd pid in parallel to capture the exact thing happening in winbindd.


- Kees.




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