Re: libsafe and Debian installation
Wilmer van der Gaast <lintux@bigfoot.com> writes:
> Isn't a buffer overflow protection especially useful for daemons and
> set-uid programs? And .. Well.. Ever tried to use LD_PRELOAD with
> set-uid binaries?
>
> When you really need this, it probably won't work.
According to "man ld.so":
For
setuid/setgid ELF binaries, only libraries in the
standard search directories that are also setgid
will be loaded.
There's /etc/ld.so.preload as well, of course.
According to web pages describing libsafe:
'libsafe' is based on a middleware software layer that intercepts
all function calls made to library functions known to be
vulnerable. A substitute version of the corresponding function
implements the original functionality in a way that ensures that
any buffer overflows are contained within the current stack frame,
which prevents attackers from overwriting the return address and
hijacking the control flow of a running program.
IOW, it *only* protects you against erroneous calls to functions it
knows about in advance.
Those are precisely the least interesting vulnerarbilities to protect
against, because they are the easiest to check for - you can find all
the danger areas just by grepping a source tree, rather than the
massively more time-consuming operation of reading an entire program
and convincing yourself that it's correct.
--
http://www.greenend.org.uk/rjk/
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