Date: Sat, 21 Dec 2019 00:13:43 +0200 From: Konstantin Belousov <kostikbel@gmail.com> To: Ryan Stone <rysto32@gmail.com> Cc: FreeBSD Current <freebsd-current@freebsd.org> Subject: Re: AT_EXECPATH aux_info vector contains path of interpreter when directly exec'ing rtld Message-ID: <20191220221343.GO32279@kib.kiev.ua> In-Reply-To: <CAFMmRNzh2qR1bT%2BvLmCMMXgmYGFCDWDU2rAcpace01H8=SAg_A@mail.gmail.com> References: <CAFMmRNzh2qR1bT%2BvLmCMMXgmYGFCDWDU2rAcpace01H8=SAg_A@mail.gmail.com>
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On Fri, Dec 20, 2019 at 04:26:41PM -0500, Ryan Stone wrote: > I've noticed that on head, if I directly execute rtld to run an > executable, AT_EXECPATH contains the path to rtld on head (on > 12.0-RELEASE it will contain nothing). This is causing me a problem > because clang uses AT_EXECPATH to preferentially locate where it's > installed, which it uses to locate its driver programs. > > The end result is that clang can no longer successfully be executed > from a process in capability mode, whereas before I could fexecve rtld > and give it a pre-opened file descriptor to /usr/bin/clang. > > I've put together a quick test program demonstrating the problem: > > https://people.freebsd.org/~rstone/getprogname.c > > On 12.0-RELEASE, directly executing rtld to run this program gives this output: > $ /libexec/ld-elf.so.1 -- ./progname > progname: progname > argv[0]: ./progname > elf_aux_info failed: No such file or directory > > On head, I get this instead: > /libexec/ld-elf.so.1 -- ./progname > progname: progname > argv[0]: ./progname > AT_EXECPATH: /libexec/ld-elf.so.1 https://reviews.freebsd.org/D22894
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