On Mon, Feb 24, 2014 at 11:50:10PM +0100, Jilles Tjoelker wrote: > On Mon, Feb 24, 2014 at 07:01:54PM +0400, Slawa Olhovchenkov wrote: > > On Mon, Feb 24, 2014 at 03:30:14PM +0100, Baptiste Daroussin wrote: > > > > On Mon, Feb 24, 2014 at 06:17:37PM +0400, Slawa Olhovchenkov wrote: > > > > On Sun, Feb 23, 2014 at 10:11:56PM +0100, Baptiste Daroussin wrote: > > > > > > As some of you may have noticed, I have imorted a couple of days > > > > > ago dma (DragonFly Mail Agent) in base. I have been asked to > > > > > explain my motivation so here they are. > > > > > What's about suid, security separations & etc? > > > > What do you mean? dma is changing user as soon as possible, dma will > > > be capsicumized, what else do you want as informations? > > > sendmail (in the past) have same behaviour (run as root and chage > > user). > > This is some security risk. > > For many scenario change user is not simple (for example -- send file > > from local user A to local user B, file with permsion 0400). > > sendmail will be forced to change behaviour -- mailnull suid program > > for place mail into queue and root daemon for deliver to user. > > This is more complex. > > Can be dma avoid this way? > > I'm a bit disappointed that dma uses setuid/setgid binaries, although it > is not a regression because sendmail also uses this Unix misfeature. > > To avoid the large attack surface of set*id binaries (the untrusted user > can set many process parameters, pass strange file descriptors, send > signals, etc), I think it is better to implement trusted submission > differently. A privileged daemon (not necessarily running as root) can > listen on a Unix domain socket and use getpeereid(3) to verify the > credentials of the client. > As long as $anyone locally can send emails, what is the point of checking getpeereid(3)?
regards, Bapt
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