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You are here: manpages

paxctl

Section: PaX (1)
Updated: 2012-02-19
Index Return to Main Contents

NAME

paxctl - user-space utility to control PaX flags

SYNTAX

paxctl <flags> <files>

DESCRIPTION

paxctl is a tool that allows PaX flags to be modified on a per-binary basis. PaX is part of common security-enhancing kernel patches and secure distributions, such as GrSecurity and Hardened Gentoo, respectively. Your system needs to be running a properly patched and configured kernel for this program to have any effect.

-P: enforce paging based non-executable pages (PAGEEXEC)
-p: do not enforce paging based non-executable pages (NOPAGEEXEC)
-E: emulate trampolines (EMUTRAMP)
-e: do not emulate trampolines (NOEMUTRAMP)
-M: enforce secure memory protections (MPROTECT)
-m: do not enforce secure memory protections (NOMPROTECT)
-R: randomize memory regions (RANDMMAP)
-r: do not randomize memory regions (NORANDMMAP)
-X: randomize base address of normal (ET_EXEC) executables (RANDEXEC)
-x: do not randomize base address of normal (ET_EXEC) executables (NORANDEXEC)
-S: enforce segmentation based non-executable pages (SEGMEXEC)
-s: do not enforce segmentation based non-executable pages (NOSEGMEXEC)
-v: view flags
-z: reset all flags (further flags still apply)
-c: create the PT_PAX_FLAGS program header if it does not exist by converting the PT_GNU_STACK program header if it exists
-C: create the PT_PAX_FLAGS program header if it does not exist by adding a new program header, if it is possible
-q: suppress error messages
-Q: report flags in short format

CAVEATS

The old PaX flag location and control method have been obsoleted, if your kernel and binaries use it you have to use chpax(1) instead (it is recommended to use PT_PAX_FLAGS along with -c or -C however).

Converting PT_GNU_STACK into PT_PAX_FLAGS means that the information in the former is destroyed, in particular you must make sure that the EMUTRAMP PaX option is properly set in the newly created PT_PAX_FLAGS. The secure way is to disable EMUTRAMP first and if PaX reports stack execution attempts from nested function trampolines then enable it.

Note that the new PT_PAX_FLAGS is created in the same state that binutils/ld itself would produce (equivalent to -zex).

Note that if you use both PT_PAX_FLAGS and the extended attribute PaX flags on a binary then they must be exactly the same (except for RANDEXEC).

Note that RANDEXEC is no longer supported by PaX kernels since 2.6.13, the paxctl flags are simply ignored there.

Note that paxctl does not make backup copies of the files it modifies.

Note that paxctl is meant to work on the native architecture's binaries only, however it should work on foreign binaries as long as they have the same endianess as the native architecture (e.g., an i386 paxctl should work on amd64 or little-endian arm but not on big-endian mips binaries).

AUTHOR

Written by The PaX Team <pageexec@freemail.hu>

This manpage was adapted from the chpax manpage written by Martin F. Krafft <madduck@debian.org> for the Debian GNU/Linux Distribution, but may be used by others.