Date: Tue, 12 Aug 2003 11:21:23 -0400 From: "James F. Hranicky" <jfh@cise.ufl.edu> To: freebsd-current@freebsd.org Subject: Bug in nss compat code? Message-ID: <20030812112123.1aac6b41.jfh@cise.ufl.edu>
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I think I've found a few bugs in the NSS code for FreeBSD 5.1 . I'm not
sure of the best way to split them up, so I'll list them all here.
FreeBSD version:
% uname -a
FreeBSD myrtle 5.1-CURRENT FreeBSD 5.1-CURRENT #1:
Mon Aug 11 17:15:47 EDT 2003
root@myrtle:/private/freebsd-src/obj/private/freebsd-src/src/sys/CISEKERN
i386
1) getnetgrent still seems to ignore the NIS netgroup maps and only uses
/etc/netgroup. A '+' as the only entry in /etc/netgroup does not force
an NIS netgroup map lookup. This bug has been reported in the 4.x tree
as well.
2) There's an odd bug in sshd/nss when the following are configured:
- nsswitch.conf
passwd: compat
- sshd_config
ChallengeResponseAuthentication yes (default)
HostbasedAuthentication yes
When /etc/netgroup doesn't exist, the sshd hangs when logging in with
HostbasedAuthentication:
<root@myrtle:~> # gdb /usr/sbin/sshd
GNU gdb 5.2.1 (FreeBSD)
(gdb) run -d -p 987
[ some debugging output deleted for readability]
debug1: KEX done
debug1: userauth-request for user jfh service ssh-connection method none
debug1: attempt 0 failures 0
debug1: PAM: initializing for "jfh"
debug1: PAM: setting PAM_RHOST to "waterspout.cise.ufl.edu"
Failed none for jfh from 128.227.205.52 port 47962 ssh2
Failed none for jfh from 128.227.205.52 port 47962 ssh2
debug1: userauth-request for user jfh service ssh-connection method hostbased
debug1: attempt 1 failures 1
debug1: userauth_hostbased: cuser jfh chost waterspout.cise.ufl.edu. pkalg ssh-dss slen 55
Failed hostbased for jfh from 128.227.205.52 port 47962 ssh2
debug1: userauth-request for user jfh service ssh-connection method hostbased
debug1: attempt 2 failures 2
debug1: userauth_hostbased: cuser jfh chost waterspout.cise.ufl.edu. pkalg ssh-rsa slen 143
Failed hostbased for jfh from 128.227.205.52 port 47962 ssh2
debug1: userauth-request for user jfh service ssh-connection method keyboard-interactive
debug1: attempt 3 failures 3
debug1: keyboard-interactive devs
debug1: auth2_challenge: user=jfh devs=
debug1: kbdint_alloc: devices 'pam'
debug1: auth2_challenge_start: trying authentication method 'pam'
^C
Program received signal SIGINT, Interrupt.
0x282e987f in read () at {standard input}:15
15 {standard input}: No such file or directory.
in {standard input}
Current language: auto; currently asm
(gdb) Quit
(gdb) where
#0 0x282e987f in read () at {standard input}:15
#1 0x281409ab in atomicio (f=0x5, fd=-1077940208, _s=0xbfbff038, n=674583073)
at /private/freebsd-src/src/crypto/openssh/atomicio.c:45
#2 0x281286a9 in ssh_msg_recv (fd=5, m=0xbfbff010) at /private/freebsd-src/src/crypto/openssh/msg.c:58
#3 0x08062bb5 in pam_query (ctx=0x807a870, name=0x7, info=0x7, num=0xbfbff064, prompts=0xbfbff068,
echo_on=0xbfbff06c) at /private/freebsd-src/src/crypto/openssh/auth2-pam-freebsd.c:397
#4 0x0805ef2a in mm_answer_pam_query (socket=3, m=0xbfbff0a0)
at /private/freebsd-src/src/crypto/openssh/monitor.c:799
#5 0x0805e51a in monitor_read (pmonitor=0x8075580, ent=0x8070320, pent=0xbfbff0ec)
at /private/freebsd-src/src/crypto/openssh/monitor.c:388
#6 0x0805e208 in monitor_child_preauth (pmonitor=0x8075580)
at /private/freebsd-src/src/crypto/openssh/monitor.c:301
#7 0x0804ed1f in privsep_preauth () at /private/freebsd-src/src/crypto/openssh/sshd.c:605
#8 0x0805087a in main (ac=47962, av=0x807a7b0) at /private/freebsd-src/src/crypto/openssh/sshd.c:1523
#9 0x0804e1a2 in _start (ap=0xbfbffb24 "/usr/sbin/sshd")
at /private/freebsd-src/src/lib/csu/i386-elf/crt1.c:104
With either ChallengeResponseAuthentication or HostbasedAuthentication
disabled, I'm prompted for a password. With both enabled, sshd hangs
here, and I'm never prompted for a password on the client side.
However, if /etc/netgroup does exist and is populated with netgroup info, I get a core dump in sshd:
(gdb) run -d -p 987
[ ... ]
debug1: KEX done
debug1: userauth-request for user jfh service ssh-connection method none
debug1: attempt 0 failures 0
debug1: PAM: initializing for "jfh"
debug1: PAM: setting PAM_RHOST to "waterspout.cise.ufl.edu"
Failed none for jfh from 128.227.205.52 port 47968 ssh2
Failed none for jfh from 128.227.205.52 port 47968 ssh2
debug1: userauth-request for user jfh service ssh-connection method hostbased
debug1: attempt 1 failures 1
debug1: userauth_hostbased: cuser jfh chost waterspout.cise.ufl.edu. pkalg ssh-dss slen 55
Program received signal SIGSEGV, Segmentation fault.
0x2830d7d7 in getnetgrent (hostp=0x80db2b0, userp=0x80db2b0, domp=0x80db2b0)
at /private/freebsd-src/src/lib/libc/gen/getnetgrent.c:231
(gdb) where
#0 0x2830d7d7 in getnetgrent (hostp=0x80db2b0, userp=0x80db2b0, domp=0x80db2b0)
at /private/freebsd-src/src/lib/libc/gen/getnetgrent.c:231
#1 0x2830cfdd in compat_passwd (retval=0xbfbfee28, mdata=0x2, ap=0x4 <Error reading address 0x4: Bad address>)
at /private/freebsd-src/src/lib/libc/gen/getpwent.c:1531
#2 0x2833091b in _nsdispatch (retval=0xbfbfee28, disp_tab=0x28362020, database=0x2835bd87 "passwd",
method_name=0x2835bdad "getpwuid_r", defaults=0x28361ec0)
at /private/freebsd-src/src/lib/libc/net/nsdispatch.c:601
#3 0x2830aa95 in getpwuid_r (uid=135115440, pwd=0x28369580,
buffer=0x80db2b0 <Error reading address 0x80db2b0: Bad address>, bufsize=135115440, result=0xbfbfee28)
at /private/freebsd-src/src/lib/libc/gen/getpwent.c:332
#4 0x2830ac9b in wrap_getpwuid_r (key=
{name = 0x80db2b0 <Error reading address 0x80db2b0: Bad address>, uid = 135115440}, pwd=0x80db2b0,
buffer=0x80db2b0 <Error reading address 0x80db2b0: Bad address>, bufsize=135115440, res=0x80db2b0)
at /private/freebsd-src/src/lib/libc/gen/getpwent.c:406
#5 0x2830ab9b in getpw (fn=0x2830ac60 <wrap_getpwuid_r>, key={name = 0xbfbfee28 "", uid = 3217026600})
at /private/freebsd-src/src/lib/libc/gen/getpwent.c:377
#6 0x2830ad49 in getpwuid (uid=135115440) at /private/freebsd-src/src/lib/libc/gen/getpwent.c:434
#7 0x2812df7f in tilde_expand_filename (filename=0x8068d41 "/.ssh/known_hosts", my_uid=135115440)
at /private/freebsd-src/src/crypto/openssh/tildexpand.c:48
#8 0x08056be6 in check_key_in_hostfiles (pw=0x8079400, key=0x8089100,
host=0x808c160 "waterspout.cise.ufl.edu",
sysfile=0x80db2b0 <Error reading address 0x80db2b0: Bad address>, userfile=0x8068d40 "~/.ssh/known_hosts")
at /private/freebsd-src/src/crypto/openssh/auth.c:389
#9 0x080620df in hostbased_key_allowed (pw=0x8079400, cuser=0x80890e0 "jfh",
chost=0x808c1c0 "waterspout.cise.ufl.edu", key=0x8089100)
at /private/freebsd-src/src/crypto/openssh/auth2-hostbased.c:164
#10 0x0805f410 in mm_answer_keyallowed (socket=135115440, m=0xbfbff070)
at /private/freebsd-src/src/crypto/openssh/monitor.c:909
#11 0x0805e51a in monitor_read (pmonitor=0x8075580, ent=0x8070344, pent=0xbfbff0bc)
at /private/freebsd-src/src/crypto/openssh/monitor.c:388
#12 0x0805e208 in monitor_child_preauth (pmonitor=0x8075580)
at /private/freebsd-src/src/crypto/openssh/monitor.c:301
#13 0x0804ed1f in privsep_preauth () at /private/freebsd-src/src/crypto/openssh/sshd.c:605
#14 0x0805087a in main (ac=47968, av=0x807a7b0) at /private/freebsd-src/src/crypto/openssh/sshd.c:1523
#15 0x0804e1a2 in _start (ap=0xbfbffb00 "/usr/sbin/sshd")
at /private/freebsd-src/src/lib/csu/i386-elf/crt1.c:104
If I switch to
passwd: nis files
in /etc/nsswitch.conf, the following happen:
- /etc/netgroup with netgroup info : login without password
(Hostbased)
- /etc/netgroup non-existent,
empty, or containing '+' : login with password
Let me know if I can do any further testing/debugging on my end.
----------------------------------------------------------------------
| Jim Hranicky, Senior SysAdmin UF/CISE Department |
| E314D CSE Building Phone (352) 392-1499 |
| jfh@cise.ufl.edu http://www.cise.ufl.edu/~jfh |
----------------------------------------------------------------------
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