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   execstack    ( 8 )

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Имя (Name)

execstack - tool to set, clear, or query executable stack flag of ELF binaries and shared libraries

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Синопсис (Synopsis)

execstack [OPTION...] [FILES]

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Описание (Description)

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.

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Параметры (Options)

-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.

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Аргументы (Arguments)

Command line arguments should be names of ELF binaries and shared libraries which should be modified or queried.

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Примеры (Examples)

# 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.

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Смотри также (See also)

ld.so(8).

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Ошибки (баги) (Bugs)

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.

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