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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | ARGUMENTS | EXAMPLES | SEE ALSO | BUGS | AUTHORS | COLOPHON |
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execstack(8) System Manager's Manual execstack(8)
execstack - tool to set, clear, or query executable stack flag of
ELF binaries and shared libraries
execstack [OPTION...] [FILES]
execstack is a program which sets, clears, or queries executable
stack flag of ELF binaries and shared libraries. Linux has in the
past allowed execution of instructions on the stack and there are
lots of binaries and shared libraries assuming this behaviour.
Furthermore, GCC trampoline code for e.g. nested functions
requires executable stack on many architectures. To avoid
breaking binaries and shared libraries which need executable
stack, ELF binaries and shared libraries now can be marked as
requiring executable stack or not requiring it. This marking is
done through the p_flags field in the PT_GNU_STACK program header
entry. If the marking is missing, kernel or dynamic linker need
to assume it might need executable stack. The marking is done
automatically by recent GCC versions (objects using trampolines on
the stack are marked as requiring executable stack, all other
newly built objects are marked as not requiring it) and linker
collects these markings into marking of the whole binary or shared
library. The user can override this at assembly time (through
--execstack or --noexecstack assembler options), at link time
(through -z execstack or -z noexecstack linker options) and using
the execstack tool also on an already linker binary or shared
library. This tool is especially useful for third party shared
libraries where it is known that they don't need executable stack
or testing proves it.
-s --set-execstack
Mark binary or shared library as requiring executable
stack.
-c --clear-execstack
Mark binary or shared library as not requiring executable
stack.
-q --query
Query executable stack marking of binaries and shared
libraries. For each file it prints either - when
executable stack is not required, X when executable stack
is required or ? when it is unknown whether the object
requires or doesn't require executable stack (the marking
is missing).
-V Print execstack version and exit.
-? --help
Print help message.
--usage
Print a short usage message.
Command line arguments should be names of ELF binaries and shared
libraries which should be modified or queried.
# execstack -s ~/lib/libfoo.so.1
will mark ~/lib/libfoo.so.1 as requiring executable stack.
# execstack -c ~/bin/bar
will mark ~/bin/bar as not requiring executable stack.
# execstack -q ~/lib/libfoo.so.1 ~/bin/bar
will query executable stack marking of the given files.
ld.so(8).
execstack doesn't support yet marking of executables if they do
not have PT_GNU_STACK program header entry nor they have room for
program segment header table growth.
Jakub Jelinek <jakub@redhat.com>.
This page is part of the prelink (prelink ELF shared libraries and
binaries) project. Information about the project can be found at
⟨http://people.redhat.com/jakub/prelink/⟩. It is not known how to
report bugs for this man page; if you know, please send a mail to
man-pages@man7.org. This page was obtained from the tarball
prelink-20130503.tar.bz2 fetched from
⟨http://people.redhat.com/jakub/prelink/⟩ on 2025-02-02. If you
discover any rendering problems in this HTML version of the page,
or you believe there is a better or more up-to-date source for the
page, or you have corrections or improvements to the information
in this COLOPHON (which is not part of the original manual page),
send a mail to man-pages@man7.org
28 October 2003 execstack(8)
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HTML rendering created 2025-02-02 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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