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Message-ID: <20110816114730.GO132@brightrain.aerifal.cx> Date: Tue, 16 Aug 2011 07:47:30 -0400 From: Rich Felker <dalias@...ifal.cx> To: musl@...ts.openwall.com Subject: Re: LD_PRELOAD and RTLD_NEXT support On Tue, Aug 16, 2011 at 10:34:10AM +0400, Vasiliy Kulikov wrote: > Rich, > > On Tue, Aug 16, 2011 at 01:17 -0400, Rich Felker wrote: > > (fully disabled for any suid/sgid binary) > > if ((aux[0]&0x7800)!=0x7800 || aux[AT_UID]!=aux[AT_EUID] > || aux[AT_GID]!=aux[AT_EGID]) { > > Two things here: > > 1) This check should be extended to support AT_SECURE (dumpable flag, > any LSM security domains, capabilities). Indeed, I'll add this. Do I just check for aux[AT_SECURE] != 0? > 2) As you check for (aux[0] & 0x7800) you assume some of these elements > can be absent. I feel it's wrong to assume you're not s*id'ed in this You misread the test. Absence of any of the 4 fields causes the program to be treated as if it were suid. > case. Instead, it's better to check for (getuid()!=geteuid() || > getgid()!=getegid()). I don't see how this helps, and this takes us down the glibc path of abysmal startup times for every tiny program called from ./configure, which is the reason ./configure takes so damn long... Rich
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