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Length: 1367 (0x557)
Types: TextFile
Names: »programing-tip-system-call«
└─⟦4f9d7c866⟧ Bits:30007245 EUUGD6: Sikkerheds distributionen
└─⟦this⟧ »./misc/programing-tip-system-call«
From mojo!mimsy!haven!aplcen!uunet!pdn!tscs!tct!chip Fri May 18 15:48:50 EDT 1990
Article: 22837 of comp.unix.questions:
Xref: mojo comp.lang.c:27559 comp.unix.questions:22837
Path: mojo!mimsy!haven!aplcen!uunet!pdn!tscs!tct!chip
From: chip@tct.uucp (Chip Salzenberg)
Newsgroups: comp.lang.c,comp.unix.questions
Subject: Re: Controlling stdin and stdouts of other executables
Message-ID: <26405616.54D3@tct.uucp>
Date: 3 May 90 16:02:30 GMT
References: <3967@hcx1.SSD.CSD.HARRIS.COM> <6418@star.cs.vu.nl> <1990May2.063730.5867@Neon.Stanford.EDU>
Followup-To: comp.unix.questions
Organization: ComDev/TCT, Sarasota, FL
Lines: 18
[Unix-specific; followups to comp.unix.questions]
According to dkeisen@Gang-of-Four.Stanford.EDU (Dave Eisen):
>system ("command > /dev/null 2>&1");
Beware system(). It calls /bin/sh to do its dirty work, which is one
reason it's so attractive to novice Unix programmers. However, if
anything in the command line is non-constant, then system() usally is
a security hole. Ignoring buffer size issues for the moment,
consider:
sprintf(buf, "/usr/lib/sendmail -oem '%s' <%s", address, tempfile);
system(buf);
Looks great, right? But what if the address is "'; rm -rf $HOME; '"?
Bzzt! You lose the security sweepstakes. I hope you have backups...
--
Chip Salzenberg at ComDev/TCT <chip%tct@ateng.com>, <uunet!ateng!tct!chip>