Date: Sat, 9 Aug 2025 09:23:39 -0400 From: Michael Sierchio <kudzu@tenebras.com> To: =?UTF-8?Q?Dag=2DErling_Sm=C3=B8rgrav?= <des@freebsd.org> Cc: questions@freebsd.org Subject: Re: shebanged script not executed right - wth Message-ID: <CAHu1Y73TiEL1vYvBt2_d=tDYKS8L8dGFjfKiwYWMf%2Bw%2BpA5_Qw@mail.gmail.com> In-Reply-To: <861ppk1w8j.fsf@ltc.des.dev> References: <N2fQGG8xsXO132Bf@aceecat.org> <38974.1754741865@ruk.vpn.home.arpa> <86a5481xax.fsf@ltc.des.dev> <865xew1ww9.fsf@ltc.des.dev> <861ppk1w8j.fsf@ltc.des.dev>
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[-- Attachment #1 --] On Sat, Aug 9, 2025 at 9:05 AM Dag-Erling Smørgrav <des@freebsd.org> wrote: > > I found the place in the code that prevents double indirection, in > sys/kern/imgact_shell.c: > > /* > * Don't allow a shell script to be the shell for a shell > * script. :-) > */ > if (imgp->interpreted & IMGACT_SHELL) > return (ENOEXEC); > > We could remove this with no ill effects, but I'm not sure we want to. Loop detection? Privilege escalation prevention? I might be entirely wrong, but the potential hazards seem to outweigh any possibly benefit. [-- Attachment #2 --] <div dir="ltr"><div dir="ltr">On Sat, Aug 9, 2025 at 9:05 AM Dag-Erling Smørgrav <<a href="mailto:des@freebsd.org">des@freebsd.org</a>> wrote:</div><div class="gmail_quote gmail_quote_container"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><br> I found the place in the code that prevents double indirection, in<br> sys/kern/imgact_shell.c:<br> <br> /*<br> * Don't allow a shell script to be the shell for a shell<br> * script. :-)<br> */<br> if (imgp->interpreted & IMGACT_SHELL)<br> return (ENOEXEC);<br> <br> We could remove this with no ill effects, but I'm not sure we want to.</blockquote><div><br></div><div>Loop detection? Privilege escalation prevention? I might be entirely wrong, but the potential hazards seem to outweigh any possibly benefit. </div></div></div>help
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