IRC, freenode, #hurd, 2011年11月26日

<antrik> BTW, how much effort is necessary to fix dbus?
<pinotree> basically, have pflocal know who's the sender
 (pid/uid/gid/groups) in the socket send op

IRC, freenode, #hurd, 2011年12月16日

<braunr> pinotree: what's the problem with dbus ?
<pinotree> braunr: select() returning 0 changed fd's with very short (eg <
 1ms) timeouts when there are actually events;

select.

<pinotree> and missing socket credentials

sendmsg scm creds.

<braunr> oh
<braunr> which socket creds interface ?
<pinotree> bsd, i.e. with SCM_CREDENTIALS payload for cmsg on
 {recv,send}msg()
<braunr> ok
<braunr> SCM_RIGHTS too ?
<braunr> the select issue seems weird though
<pinotree> hm no, that's for passing fd's to other processes
<braunr> is it specific to pflocal or does dbus use pfinet too ?
<pinotree> iirc on very short timeouts the application has no time waiting
 for the reply of servers
<braunr> i see
<pinotree> braunr: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=79358
<braunr> thanks
<pinotree> (the interesting messages are from #53 and on)
<braunr> 2000 eh ... :)
<braunr> hm i agree with neal, i don't understand why the timeout is given
 to the kernel as part of the mach_msg call

IRC, freenode, #hurd, 2011年12月20日

<braunr> hm, i don't see any occurrence of SCM_CREDENTIALS in dbus
<braunr> only SCM_RIGHTS
<pinotree> braunr: yes, that one
<braunr> oh
<braunr> i thought you said the opposite last time
<pinotree> dbus/dbus-sysdeps-unix.c, write_credentials_byte and
 _dbus_read_credentials_socket (with #define HAVE_CMSGCRED)
<braunr> hm
<braunr> which version ?
<braunr> i don't see anything in 1.4.16
<pinotree> 1.4.16
<braunr> grmbl
<braunr> ah, i see
<braunr> SCM_CREDS
<pinotree> if you want, i have a simplier .c source with it
<braunr> no i'm just gathering info
<pinotree> ok
<braunr> what's the deal with SCM_CREDS and SCM_CREDENTIALS ?
<braunr> bsd vs sysv ?
<braunr> oh, http://lists.debian.org/debian-hurd/2002/03/msg00135.html
<braunr> so we actually do want both SCM_CREDS and SCM_RIGHTS for debus
<braunr> dbus
<pinotree> SCM_RIGHTS is a different matter, it is for passing fd's
<braunr> yes
<braunr> but it's used by dbus
<braunr> so if we can get it, it should help too
<pinotree> there's a preliminary patch for it done by emilio time ago, and
 iirc it's applied to debian's glibc
<braunr> ah, he changed the libc
<braunr> right, that's the only sane way
<pinotree> iirc roland didn't like one or more parts of it (but i could be
 wrong)
<braunr> ok

IRC, freenode, #hurd, 2013年07月17日

<teythoon> btw pinotree, what happened to your efforts to make dbus work?
<pinotree> not much, my initial patch was just a crude hack, a better
 solution requires more thinkering and work 
<teythoon> yes, ive seen that
<teythoon> but that was only a tiny patch against the libc, surely there
 must be more to that?
<pinotree> not really
<teythoon> and the proper fix is to patch pflocal to query the auth server
 and add the credentials?
<pinotree> possibly
<teythoon> that doesn't sound to bad, did you give it a try?
<pinotree> not really, got caught in other stuff

IRC, freenode, #hurd, 2013年09月02日

<gnu_srs1> something is wrong with libc0.3 since the switch to 2.17. dbus
 does not run any longer when rebuilt
<gnu_srs1> the latest build of dbus was with 2.13: libc0.3-dev: already
 installed (2.13-38)
<pinotree> debug it
<gnu_srs1> Yes, I will. Maybe somebody could rebuild it and verify my
 findings?
<pinotree> gnu_srs1: your finding is "doesn't work", which is generic and
 does not help without investigation
<gnu_srs1> just rebuild it and: e.g. ./build-debug/bus/dbus-daemon --system
 (--nofork)
<pinotree> gnu_srs1: please, debug it
<gnu_srs1> I have partially already. But maybe the problems only shows on
 my box. I'll rebuild on another box before continuing debugging.
<pinotree> gnu_srs1: are you, by chance, running a libc or something else
 with your scm_creds work?
<gnu_srs1> I did, but I've backed to 2.17-92 right now.
<gnu_srs1> sane problem with dbus on another box, something's fishy:-(
<gnu_srs1> braunr: any good way to find out if the dbus problems are with
 libpthread? Setting a breakpoint with libc0.3-dbg installed.
<braunr> gnu_srs1: i don't know

See glibc, Missing interfaces, amongst many more, SOCK_CLOEXEC.

IRC, freenode, #hurd, 2013年09月04日

<gnu_srs> Hi, looks like dbus requires abstract socket namespace: #undef
 HAVE_ABSTRACT_SOCKETS What's missing?
<pinotree> uh?
<pinotree> abstract unix sockets are a Linux feature, and surely it is not
 mandatory for dbus
<gnu_srs> Looks like dbus exits if they are not supported:
<gnu_srs> dbus_set_error (error, DBUS_ERROR_NOT_SUPPORTED, "Operating
 system does not support abstract socket namespace\n");  _dbus_close
 (listen_fd, NULL); 1061 return -1;
<pinotree> that is enclosed in a if (abstract)
<pinotree> and that parameter is set to true in other places (eg
 dbus/dbus-server-unix.c) only when HAVE_ABSTRACT_SOCKETS is defined
<pinotree> so no, abstract sockets are not mandatory
<gnu_srs> Well this code is executed e.g. when running emacs remotely in
 X. Have to dig deeper then to see why.
<pinotree> maybe it could have to do the fact that your dbus server is
 running in linux and runs by default using such sockets type
<pinotree> but yes, you need to dig better
<gnu_srs> pinotree: You are right. when running natively the problem is:
<pinotree> *drums*
<gnu_srs> Manually: Process /usr/lib/at-spi2-core/at-spi-bus-launcher
 exited with status 1
<pinotree> eh?
<gnu_srs> Error retrieving accessibility bus address:
 org.freedesktop.DBus.Error.Spawn.ChildExited: ^
<pinotree> most probably that service does not start due to the lack of
 socket credentials which affects dbus
<pinotree> uninstall or disable those additional services, they are not
 your problem
<gnu_srs> credentials is enabled. which services to remove?
<pinotree> dunno

IRC, freenode, #hurd, 2013年09月11日

<gnu_srs> Hi, looks like frebsd had (2008) the same problem as hurd when
 sending credentials over PF_INET: 
<gnu_srs>
 http://lists.freebsd.org/pipermail/freebsd-hackers/2008-May/024577.html
<gnu_srs> Since the dbus code is about the same now (2013), maybe they
 added support?
<gnu_srs> The next message in the thread confirms that the dbus code is
 invalid, does anybody have pointers?
<pinotree> from what i've seen so far, socket credentials are done only for
 local sockets (ie PF_UNIX)
<pinotree> i don't see how things like uid/gid/pid of the socket endpoint
 can have anything to do with AF_INET
<pinotree> and socket credentials in dbus are used only in the [local]
 socket transport, so there's no issue

IRC, freenode, #hurd, 2013年09月12日

<gnu_srs> pinotree: Yes, there is an issue with dbus and AF_INET, see
 test/corrupt.c: tests /corrupt/tcp and /corrupt/byte-order/tcp:-/
<pinotree> gnu_srs: what's wrong with those? they are just testing the
 connection over a tcp socket
<pinotree> as said above, socket credentials shouldn't be used in such
 cases
<gnu_srs> They are, see also test/relay.c: /relay and /limit tests:-(
<pinotree> how are they?
<pinotree> please be more specifc...
<gnu_srs> Just run the tests yourself with DBUS_VERBOSE=1
<pinotree> you are claiming there is a problem, so please specify what is
 the actual issue
<gnu_srs> DBUS_VERBOSE=1 build-debug/test/test-relay 
<pinotree> you are claiming there is a problem, so please specify what is
 the actual issue
<gnu_srs> same with test-corrupt
<gnu_srs> look at the verbose output: Failed to write credentials: Failed
 to write credentials byte: Invalid argument
<gnu_srs> coming from pfinet since PF_INET is used.
<pinotree> check what it does on linux then
<pinotree> put an abort() at the start of the read/write socket credential
 functions in dbus-sysdeps-unix.c and see whether it is triggered also on
 linux
<gnu_srs> SO_PEERCRED is used for linux and LOCAL_CREDS is used for
 kfreebsd, so we are on our own here:-/
<pinotree> and linux' SO_PEERCRED works also on AF_INET sockets? i'd doubt
 it
<gnu_srs>
 http://stackoverflow.com/questions/10037086/so-peercred-vs-scm-credentials-why-there-are-both-of-them
<pinotree> yes, i know the difference, but please read what i asked again
<gnu_srs> I'll check to be sure...
<braunr> gnu_srs: user credentials are not supposed to be passed through an
 AF_INET socket
<braunr> how hard is that to understand ?
<gnu_srs> OK, linux use send since CMSGCREDS is not defined to write
 credentials. Working on how they are received.
<gnu_srs> braunr: I do understand, but the dbus code tries to do that for
 Hurd:-(
<pinotree> then it should do that on linux too
<pinotree> (since the local socket credentials code is isolated in own
 functions, and they are called only for the unix transport)
<gnu_srs> Happiness:-D, almost all dbus tests pass!
<gnu_srs> 17(17) dbus tests pass:)
<braunr> gnu_srs: hopefully your patch does things right
<gnu_srs> which patch
<braunr> adding credentials through unix socket
<braunr> isn't that what you're doing ?
<gnu_srs> the mail to MLs is from the stock installed packages.
<braunr> ?
<gnu_srs> the test reports are with the SCM_CREDS patches, but I stumbled
 on the SCM_RIGHTS issues reported to MLs
<gnu_srs> no patches applied, just test the attached file yourself.
<braunr> so what's your work about ?
<gnu_srs> I'm working on SCM_CREDS, yes, and created patches for dbus,
 glib2.0 and libc.
<gnu_srs> the mail was about some bug in the call to io_restrict_auth in
 sendmsg.c: without any of my patches applied (another image) 
<teythoon> gnu_srs: you have to give us more context, how are we supposed
 to know how to find this sendmsg.c file?
<pinotree> (it's in glibc, but otherwise the remark is valid)
<pinotree> s/otherwise/anyway/

Emails

IRC, freenode, #hurd, 2013年10月16日

<braunr> gnu_srs: how could you fail to understand credentials need to be
 checked ?
<gnu_srs> braunr: If data is sent via sendmsg, no problem, right?
<braunr> gnu_srs: that's irrelevant
<gnu_srs> It's just to move the check to the receive side.
<braunr> and that is the whole problem
<braunr> it's not "just" doing it
<braunr> first, do you know what the receive side is ?
<braunr> do you know what it can be ?
<braunr> do you know where the corresponding source code is to be found ?
<gnu_srs> please, describe a scenario where receiving faulty ancillary data
 could be a problem instead
<braunr> dbus
<braunr> a user starting privileged stuff although he's not part of a
 privileged group of users for example
<braunr> gnome, kde and others use dbus to pass user ids around
<braunr> if you can't rely on these ids being correct, you can compromise
 the whole system
<braunr> because dbus runs as root and can give root privileges
<braunr> or maybe not root, i don't remember but a system user probably
<pinotree> "messagebus"
<gnu_srs> k!
<braunr> see http://www.gnu.org/software/hurd/open_issues/dbus.html
<braunr> IRC, freenode, #hurd, 2013年07月17日
<braunr> <teythoon> and the proper fix is to patch pflocal to query the
 auth server and add the credentials?
<braunr> <pinotree> possibly
<braunr> <teythoon> that doesn't sound to bad, did you give it a try?

IRC, freenode, #hurd, 2013年10月22日

<gnu_srs> I think I have a solution on the receive side for SCM_CREDS :)
<gnu_srs> A question related to SCM_CREDS: dbus use a zero data byte to get
 credentials sent.
<gnu_srs> however, kfreebsd does not care which data (and credentials) is
 sent, they report the credentials anyway
<gnu_srs> should the hurd implementation do the same as kfreebsd?
<youpi> gnu_srs: I'm not sure to understand: what happens on linux then?
<youpi> does it see zero data byte as being bogus, and refuse to send the
 creds?
<gnu_srs> linux is also transparent, it sends the credentials independent
 of the data (but data has to be non-null)
<youpi> ok
<youpi> anyway, what the sending application writes does not matter indeed
<youpi> so we can just ignore that
<youpi> and have creds sent anyway
<braunr> i think the interface normally requires at least a byte of data
 for ancilliary data
<youpi> possibly, yes
<braunr> To pass file descriptors or credentials over a SOCK_STREAM,
 you need to send or
<braunr> receive at least one byte of non-ancillary data in
 the same sendmsg(2) or
<braunr> recvmsg(2) call.
<braunr> but that may simply be linux specific
<braunr> gnu_srs: how do you plan on implementing right checking ?
<gnu_srs> Yes, data has to be sent, at least one byte, I was asking about
 e.g. sending an integer 
<braunr> just send a zero
<braunr> well
<braunr> dbus already does that
<braunr> just don't change anything
<braunr> let applications pass the data they want
<braunr> the socket interface already deals with port rights correctly
<braunr> what you need to do is make sure the rights received match the
 credentials
<gnu_srs> The question is to special case on a zero byte, and forbid
 anything else, or allow any data.
<braunr> why would you forbid 
<braunr> ?
<gnu_srs> linux and kfreebsd does not special case on a received zero byte
<braunr> same question, why would you want to do that ?
<gnu_srs> linux sends credentials data even if no SCM_CREDENTIALS structure
 is created, kfreebsd don't
<braunr> i doubt that
<gnu_srs> To be specific:msgh.msg_control = NULL; msgh.msg_controllen = 0;
<braunr> bbl
<gnu_srs> see the test code:
 http://lists.debian.org/debian-hurd/2013/08/msg00091.html
<braunr> back
<braunr> why would the hurd include groups when sending a zero byte, but
 only uid when not ?
<gnu_srs> ?
<braunr> 1) Sent credentials are correct:
<braunr> no flags: Hurd: OK, only sent ids
<braunr> -z Hurd: OK, sent IDs + groups
<braunr> and how can it send more than one uid and gid ?
<braunr> "sent credentials are not honoured, received ones are created"
<gnu_srs> Sorry, the implementation is changed by now. And I don't special
 case on a zero byte.
<braunr> what does this mean ?
<braunr> then why give me that link ?
<gnu_srs> The code still applies for Linux and kFreeBSD. 
<gnu_srs> It means that whatever you send, the kernel emits does not read
 that data: see
<gnu_srs> socket.h: before struct cmsgcred: the sender's structure is
 ignored ...
<braunr> do you mean receiving on a socket can succeed with gaining
 credentials, although the sender sent wrong ones ?
<gnu_srs> Looks like it. I don't have a kfreebsd image available right now.
<gnu_srs> linux returns EPERM
<braunr> anyway
<braunr> how do you plan to implement credential checking ?
<gnu_srs> I'll mail patches RSN

IRC, freenode, #hurd, 2013年11月03日

<gnu_srs> Finally, SCM_CREDS (IDs) works:) I was on the right track all the
 time, it was just a small misunderstanding.
<gnu_srs> remains to solve the PID check
<youpi> gnu_srs: it should be a matter of adding
 proc_user/server_authenticate
<gnu_srs> there are no proc_user/server_authenticate RPCs?
<gnu_srs> do you mean adding them to process.defs (and implement them)?
<youpi> gnu_srs: I mean that, yes

IRC, freenode, #hurd, 2013年11月13日

<gnu_srs> BTW: I have to modify the SCM_RIGHTS patch to work together with
 SCM_CREDS, OK?
<youpi> probably
<youpi> depends on what you change of course

IRC, freenode, #hurd, 2013年11月15日

<gnu_srs> Hi, any ideas where this originates, gdb? warning: Error setting
 exception port for process 9070: (ipc/send) invalid destination port
<braunr> gnu_srs: what's process 9070 ?
<gnu_srs> braunr: It's a test program for sending credentials over a
 socket. Have to create a reproducible case, it's intermittent.
<gnu_srs> The error happens when running through gdb and the sending
 program is chrooted:
<gnu_srs> -rwsr-sr-x 1 root root 21156 Nov 15 15:12
 scm_rights+creds_send.chroot

IRC, freenode, #hurd, 2013年11月16日

<gnu_srs> Hi, I have a problem debugging a suid program, see
 http://paste.debian.net/66171/
<gnu_srs> I think this reveals a gnumach/hurd bug, it makes things behave
 strangely for other programs.
<gnu_srs> How to get further on with this?
<gnu_srs> Or can't I debug a suid program as non-root?
<pochu> gnu_srs: if gdb doesn't work for setuid programs on hurd, I suppose
 you could chmod -s the binary you're trying to debug, login as root and
 run it under gdb
<gnu_srs> pochu: When logged in as root the program works, independent of
 the s flag setting.
<pochu> right, probably the setuid has no effect in that case because your
 effective uid is already fine
<pochu> so you don't hit the gdb bug in that case
<pochu> (just guessing)
<gnu_srs> It doesn't work in Linux either, so it might be futile.
<gnu_srs> trying
<pochu> hmm that may be the expected behaviour. after all, gdb needs to be
 priviledged to debug priviledged processes
<gnu_srs> Problem is that it was just the suid properties I wanted to
 test:(
<braunr> gnu_srs: imagine if you could just alter the code or data of any
 suid program just because you're debugging it

IRC, freenode, #hurd, 2013年11月18日

<gnu_srs> Hi, is the code path different for a suid program compared to run
 as root?
<gnu_srs> Combined with LD_PRELOAD?
<teythoon> gnu_srs: afaik LD_PRELOAD is ignored by suid programs for
 obvious security reasons
<gnu_srs> aha, thanks:-/
<braunr> gnu_srs: what's your problem with suid ?
<gnu_srs> I made changes to libc and tried them out with
 LD_PRELOAD=... test_progam. It worked as any user (including root),
<gnu_srs> but not with suid settings. Justus explained why not.
<braunr> well i did too
<braunr> but is that all ?
<braunr> i mean, why did you test with suid programs in the first place ?
<gnu_srs> to get different euid and egid numbers
<gnu_srs> hi, anybody seen this with eglibc-2.17-96: locale: relocation
 error: locale: symbol errno,
<gnu_srs> version GLIBC_PRIVATE not defined in file libc.so.0.3 with link
 time reference
<teythoon> yes, I have
<teythoon> but afaics nothing did break, so I ignored it

IRC, freenode, #hurd, 2013年11月23日

<gnu_srs> Finally 8-)
<gnu_srs> Good news: soon both SCM_CREDS _and_ SCM_RIGHTS is supported
 jointly. RFCs will be sent soon.

IRC, freenode, #hurd, 2013年12月05日

<gnu_srs> I have a problem with the SCM_CREDS patch and dbus. gamin and my
 test code runs fine.
<gnu_srs> the problem with the dbus code is that it won't work well with 
<gnu_srs> auth_user_authenticate in sendmsg and auth_server_authenticate in
 recvmsg.
<gnu_srs> Should I try to modify the dbus code to make it work?
<youpi> unless you manage to prove that dbus is not following the posix
 standard, there is no reason why you should have to modify dbus
<gnu_srs> I think the implementation is correct,
<gnu_srs> but auth_user_authenticate hangs sendmsg until
 auth_seerver_authenticate is executed in recvmsg.
<gnu_srs> and dbus is not doing that, so it hangs in sendmsg writing a
 credentials byte.
<gnu_srs> well the credentials byte is definitely non-posix.
<gnu_srs> I found a bug related to the HURD_DPORT_USE macro too:-(
<youpi> ah, yes, auth_user_authenticate might be synchronous indeed, let me
 think about it
<gnu_srs> Nevertheless, I think it's time to publish the code so it can be
 commented on:-D
<youpi> sure
<youpi> publish early, publish often

IRC, freenode, #hurd, 2014年01月17日

<gnu_srs> youpi: as a start all our requested dbus changes are now
 committed, and in Debian unstable
<youpi> good :)

IRC, freenode, #hurd, 2014年01月30日

<pochu> dbus has some known problems
<pere> known fixes too?
<pochu> http://www.gnu.org/software/hurd/open_issues/dbus.html
<gnu_srs> pochu: Maybe that page should be updated:
 http://lists.nongnu.org/archive/html/bug-hurd/2013-12/msg00150.html
<youpi> gnu_srs: well, maybe you can do it :
<youpi> )