Re: firefox: unveil and pledge enhancements [8]

On Fri, Oct 04, 2019 at 10:00:18AM +0100, Stuart Henderson wrote:
> On 2019/10/04 09:13, Solene Rapenne wrote:
> > On Wed, Oct 02, 2019 at 10:54:36AM +0200, Solene Rapenne wrote:
> > > On Wed, Sep 25, 2019 at 11:25:59AM -0500, joshua stein wrote:
> > > > This patchset goes back to files in /etc/firefox for unveil file
> > > > lists, and goes further and moves the pledge strings to separate
> > > > files too. This should be the most secure version that is still
> > > > tweakable at runtime.
> > > >
> > > > I switched away from using Firefox's NS_LOCAL_FILE_CONTRACTID/
> > > > NS_LOCALFILEINPUTSTREAM_CONTRACTID mechanisms to read a file, since
> > > > they require a lot of internal setup to be done before they can be
> > > > used (which is otherwise a good thing, because other things later in
> > > > Firefox shouldn't have raw file access). Instead of those, I'm
> > > > using the normal C++ API for reading the /etc/firefox files and this
> > > > way I have been able to move the pledge/unveil calls earlier in the
> > > > process startup. Unfortunately this also means that I can't
> > > > dynamically detect the localized ~/Downloads directory, so if you
> > > > use a different directory, you'll just need to modify the
> > > > unveil.content and unveil.main files to change it.
> > > >
> > > > I tried the $TMPDIR shenanigans with the main process mkdtemp'ing
> > > > somewhere in $TMPDIR (or /tmp), and then exporting TMPDIR as that
> > > > directory so that everything else within Firefox uses that
> > > > subdirectory as its temp directory, allowing /tmp to be removed from
> > > > the unveil lists and only that subdirectory visible. Unfortunately
> > > > the first thing to break was our own shm_open() which hard-codes
> > > > /tmp and doesn't honor $TMPDIR. So that all was ripped out and
> > > > we're back to full access to /tmp.
> > > >
> > > > If the mailing list mangles this again, it's at
> > > > https://jcs.org/patches/firefox-port-unveil8.diff
> > > >
> > > >
> > > >
> > >
> > > In a very particular case, I get a
> > > firefox[4133]: pledge "inet", syscall 97
> > >
> > > to do so, I make a ssh tunnel to a Proxmox web interface with default
> > > certificate (auto generated)
> > >
> > > ssh -L 44444:10.4.5.6:8006 some_remote_machine
> > >
> > > then, open https://localhost:44444 on firefox, and I get a pledge error
> > > with firefox showing "Gah. Your tab just crashed."
> > >
> > > Sadly, I've not been able to reproduce this with any other certificate.
> > > It may certainly not be related to ssh tunneling, but I can't try on direct lan
> > > access.
> > >
> >
> > kdump of the process (it's not the main process) when the tab crashes
> >
> > 43463 firefox CALL socket(AF_INET6,0x1<SOCK_STREAM>,0)
> > 43463 firefox PLDG socket, "inet", errno 1 Operation not permitted
> > 43463 firefox PSIG SIGABRT SIG_DFL
> > 43463 firefox NAMI "firefox.core"
> >
>
> You may be able to figure out which process type it is, by looking at
> the earlier call to pledge() and examining the string.
>
> Or if the process was already created before opening the page you may
> also be able to figure it out from the pid if you "ps wwx" first.
>
> I wonder if a process without network pledge could be trying to fetch a
> missing intermediary cert from the address in the "CA Issuers" field in
> the cert. Might get some more information if you show the connection
> and cert from "openssl s_client -connect localhost:44444"..
>

the failing process looks like this from ps

/usr/local/lib/firefox/firefox -contentproc -childID 1 -isForBrowser
-prefsLen 170 -prefMapSize 197941 -parentBuildID 20190925193545 -appdir
/usr/local/lib/firefox/browser 44467 tab