see kern_exec.c line 600
--
Sent from a phone, apologies for poor formatting.
On 29 April 2025 21:00:26 Lloyd <ng2...@proton.me> wrote:
Sorry for the duplicate message but I have some more information to share:
I instrumented some fake sendmail binaries/scripts to I can insert myself
in between and execute a ktrace. Note that below the "/usr/sbin/send-mail"
is just a symlink to smtpctl to trigger "sendmail compat mode" of smtpd.
Unfortunately in both cases below this is the entire ktrace. I've already
eliminated mailwrapper(8) as the source of any issues as it successfully
calls smtpctl and that's where the hang is happening. Below two examples
show a call to smtpctl with default Alpine args and a forced "-t" arg:
14906 ktrace RET ktrace 0
14906 ktrace CALL execve(0x6fd7f687e0ff,0x6fd7f687df88,0x6fd7f687dfb0)
14906 ktrace NAMI "/usr/sbin/send-mail"
14906 ktrace ARGS
[0] = "/usr/sbin/send-mail"
[1] = "-bs"
[2] = "-odb"
[3] = "-oem"
18856 ktrace RET ktrace 0
18856 ktrace CALL execve(0x77fb458a4f7f,0x77fb458a4e18,0x77fb458a4e30)
18856 ktrace NAMI "/usr/sbin/send-mail"
18856 ktrace ARGS
[0] = "/usr/sbin/send-mail"
[1] = "-t"
Regards
Lloyd
On Tuesday, April 29th, 2025, Lucas Gabriel Vuotto wrote:
Hey Lloyd,
On Tue, Apr 29, 2025 at 02:00:17AM +0000, Lloyd wrote:
There is a bug in Alpine whereby out of the box it is unable to send email on
an OpenBSD box, even locally. By default, sending a message in unconfigured
Alpine will fork out to sendmail(8) which hangs for some unknown reason and
the sendmail wrapper process needs to be killed. Receiving mail works fine.
Running /usr/sbin/sendmail -t < ~/dead.letter against the abandoned message
works fine, so the interface between Alpine and the sendmail wrapper is
broken.
I ran a ktrace but couldn't find anything substantiative. Rather than debug
this further, there is a much simpler patch to get Alpine working in the
default install. The below change sets the value of smtp-server to localhost
in the file which gets copied to /etc/pine.conf on installation. With this
variable set, Alpine connects to the local smtpd over TCP rather than using
the sendmail(8) utility, if the user has no smtp server defined.
/etc/pine.conf is overridden by the user's ~/.pinerc so this should be a
non-destructive change that will not impact anything but an unconfigured
installation which falls back to using sendmail(8), which does not work.
If it did work, then I believe --with-smtp-msa-flags=-t should be set in
the Makefile as well since the hard-coded defaults pass bogus flags to
sendmail(8). This didn't work either so it really doesn't matter, I believe
the issue lies somewhere in the threading mechanism and how it forks out
to sendmail. It's possible a prior security-related change broke something.
This issue dates back to at least OpenBSD 6.8:
https://marc.info/?l=openbsd-misc&m=161141614219034&w=2
I'm not an alpine user, but got curious about this issue. Would you mind
sharing the bits of `ktrace -di alpine` related to exec functions with
me? It's important you share only those bits, as ktrace output might
include data like passwords.
For the record, I verified that adding --with-smtp-msa-flags=-t does
indeed set it in the code, so that should be working.
Lucas
