* Re: [Cooker] /bin/login from util-linux-2.11c-2mdk breaks zsh ctty hadling
[not found] ` <m3n183su14.fsf@giants.mandrakesoft.com>
@ 2001-05-27 14:07 ` Andrej Borsenkow
2001-06-06 17:12 ` Chmouel Boudjnah
0 siblings, 1 reply; 4+ messages in thread
From: Andrej Borsenkow @ 2001-05-27 14:07 UTC (permalink / raw)
To: cooker, ZSH Workers Mailing List
Chmouel Boudjnah wrote:
> Andrej Borsenkow <Andrej.Borsenkow@mow.siemens.ru> writes:
>
>
>>After I upgraded to the latest util-linux all login zsh's are running
>>without controlling tty. bash seems to run normally (attached to
>>tty). consoletype fails with EPERM that results in returning "serial"
>>instead "vt" and russian charset not activated. I had to copy
>>/bin/login from Mdk8 to be able to work.
>>
>>It is also 2.4.4-3mdk kernel
>>
>>Chmoul?
>>
>
> ????? really couldn't reproduce the problem, here...
>
>
O.K., I have found why it happens. Here goes.
Here is what happens around a fork in /bin/login for a "good" login
(1188 is login process):
1188 fork() = 1200
1188 wait4(-1, <unfinished ...>
1200 rt_sigaction(SIGINT, {SIG_DFL}, {SIG_IGN}, 8) = 0
1200 msgget(501, 0x2|02) = 0
1200 chdir("/home/bor") = 0
1200 execve("/bin/zsh", ["-zsh"], [/* 6 vars */]) = 0
Here is what happens at the same place for a "bad" login (1175 is
login). I marked offending call:
1175 fork() = 1178
1175 ioctl(0, TIOCNOTTY) = 0
1175 --- SIGHUP (Hangup) ---
1175 --- SIGCONT (Continued) ---
1175 rt_sigaction(SIGHUP, {SIG_DFL}, {SIG_IGN}, 8) = 0
1175 wait4(-1, <unfinished ...>
1178 --- SIGCONT (Continued) ---
>>> 1178 setsid() = 1178
1178 rt_sigaction(SIGHUP, {SIG_DFL}, {SIG_IGN}, 8) = 0
1178 rt_sigaction(SIGINT, {SIG_DFL}, {SIG_IGN}, 8) = 0
1178 msgget(501, 0x2|02) = 0
1178 chdir("/home/bor") = 0
1178 execve("/bin/zsh", ["-zsh"], [/* 6 vars */]) = 0
As you see, new login now does setsid(). Unfortunately, this call has a
side effect of resetting process' ctty, so anything exec'ed next runs
without controlling tty.
The reason bash still works is that it checks if /dev/tty is available,
and if not it reopens it:
2916 open("/dev/tty", O_RDWR|O_NONBLOCK|O_LARGEFILE) = -1 ENXIO (No
such device or address)
2916 ioctl(0, TCGETS, {B38400 opost isig icanon echo ...}) = 0
2916 brk(0) = 0x80c008c
2916 brk(0x80c1000) = 0x80c1000
2916 brk(0x80c3000) = 0x80c3000
2916 readlink("/proc/self/fd/0", "/dev/tty3", 4095) = 9
2916 open("/dev/tty3", O_RDWR|O_NONBLOCK|O_LARGEFILE) = 3
2916 close(3) = 0
the last two open/close pair makes current stdin to controlling tty. Zsh
does not do it - it inherits std{in,out,err} and opens its SHIN with
O_NOCTTY.
I still claim it is a /bin/login bug. It should make sure porgram is
exec'ed with correct environment that includes ctty.
-andrej
P.S. The problem is not limited to zsh - any program that expects
/dev/tty fails.
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [Cooker] /bin/login from util-linux-2.11c-2mdk breaks zsh ctty hadling
2001-05-27 14:07 ` [Cooker] /bin/login from util-linux-2.11c-2mdk breaks zsh ctty hadling Andrej Borsenkow
@ 2001-06-06 17:12 ` Chmouel Boudjnah
2001-06-06 20:48 ` Andrej Borsenkow
0 siblings, 1 reply; 4+ messages in thread
From: Chmouel Boudjnah @ 2001-06-06 17:12 UTC (permalink / raw)
To: Andrej.Borsenkow; +Cc: cooker, ZSH Workers Mailing List
Andrej Borsenkow <arvidjaar@mail.ru> writes:
> O.K., I have found why it happens. Here goes.
ok fixed in latest util-linux of cooker..
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [Cooker] /bin/login from util-linux-2.11c-2mdk breaks zsh ctty hadling
2001-06-06 17:12 ` Chmouel Boudjnah
@ 2001-06-06 20:48 ` Andrej Borsenkow
2001-06-08 19:16 ` Chmouel Boudjnah
0 siblings, 1 reply; 4+ messages in thread
From: Andrej Borsenkow @ 2001-06-06 20:48 UTC (permalink / raw)
To: Chmouel Boudjnah; +Cc: cooker, ZSH Workers Mailing List
Chmouel Boudjnah wrote:
> Andrej Borsenkow <arvidjaar@mail.ru> writes:
>
>
>>O.K., I have found why it happens. Here goes.
>>
>
> ok fixed in latest util-linux of cooker..
>
>
No, sorry. It now tries to open /dev/tty but in wrong place - in parent,
not in child.
(ttypts/2)% rpm -q util-linux
util-linux-2.11d-1mdk
1166 read(0, "b", 1) = 1
1166 read(0, "o", 1) = 1
1166 read(0, "r", 1) = 1
1166 read(0, "\n", 1) = 1
1166 execve("/bin/login", ["/bin/login", "--", "bor"], [/* 8 vars */]) = 0
...
1166 setsid() = -1 EPERM (Operation not permitted)
1166 open("/dev/tty3", O_RDWR|O_NONBLOCK|O_LARGEFILE) = 3
^^^^^^^^^^^^^^^^ useless here because ...
...
1166 fork() = 2397
2397 setsid() = 2397
^^^^^^^^ ... Oops!
2397 rt_sigaction(SIGHUP, {SIG_DFL}, {SIG_IGN}, 8) = 0
2397 rt_sigaction(SIGINT, {SIG_DFL}, {SIG_IGN}, 8) = 0
2397 msgget(501, 0x2|02) = 0
2397 chdir("/home/bor") = 0
2397 execve("/bin/zsh", ["-zsh"], [/* 6 vars */]) = 0
The same applies - setsid() in child resets ctty.
-andrej
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [Cooker] /bin/login from util-linux-2.11c-2mdk breaks zsh ctty hadling
2001-06-06 20:48 ` Andrej Borsenkow
@ 2001-06-08 19:16 ` Chmouel Boudjnah
0 siblings, 0 replies; 4+ messages in thread
From: Chmouel Boudjnah @ 2001-06-08 19:16 UTC (permalink / raw)
To: Andrej.Borsenkow; +Cc: cooker, ZSH Workers Mailing List
Andrej Borsenkow <arvidjaar@mail.ru> writes:
> Chmouel Boudjnah wrote:
>
> > Andrej Borsenkow <arvidjaar@mail.ru> writes:
> >
> >
> >>O.K., I have found why it happens. Here goes.
> >>
> >
> > ok fixed in latest util-linux of cooker..
> >
> >
>
> No, sorry. It now tries to open /dev/tty but in wrong place - in parent,
> not in child.
ok i understand now, the setsid is definitvely broken (for ash shell
:-(), i'll revert the changes here, can you try this[1] :
--- util-linux-2.11e/login-utils/login.c.chmou Thu Jun 7 20:49:09 2001
+++ util-linux-2.11e/login-utils/login.c Fri Jun 8 21:14:03 2001
@@ -1071,15 +1071,8 @@
* We must fork before setuid() because we need to call
* pam_close_session() as root.
*/
- /*
- * Problem: if the user's shell is a shell like ash that doesnt do
- * setsid() or setpgrp(), then a ctrl-\, sending SIGQUIT to every
- * process in the pgrp, will kill us.
- * Solution: use TIOCNOTTY and setsid().
- */
signal(SIGINT, SIG_IGN);
- signal(SIGHUP, SIG_IGN); /* ignore signal from TIOCNOTTY below */
-
+
childPid = fork();
if (childPid < 0) {
int errsv = errno;
@@ -1088,18 +1081,11 @@
PAM_END;
exit(0);
} else if (childPid) {
- /* parent - wait for child to finish, then cleanup session */
- ioctl(0, TIOCNOTTY, NULL);
- signal(SIGHUP, SIG_DFL);
-
wait(NULL);
PAM_END;
exit(0);
}
/* child */
- setsid();
- /* reopen, as we need controlling tty in the child */
- opentty(ttyn);
#endif
signal(SIGHUP, SIG_DFL);
signal(SIGINT, SIG_DFL);
Footnotes:
[1] or get the file https://qa.mandrakesoft.com/~chmou/misc/login
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2001-06-08 19:17 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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[not found] <3B0BF59E.6030408@mow.siemens.ru>
[not found] ` <m3n183su14.fsf@giants.mandrakesoft.com>
2001-05-27 14:07 ` [Cooker] /bin/login from util-linux-2.11c-2mdk breaks zsh ctty hadling Andrej Borsenkow
2001-06-06 17:12 ` Chmouel Boudjnah
2001-06-06 20:48 ` Andrej Borsenkow
2001-06-08 19:16 ` Chmouel Boudjnah
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