grsecurity forums

I just tried running paxtest on my system. Here are the results.

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Executable anonymous mapping             : Killed
Executable bss                           : Killed
Executable data                          : Killed
Executable heap                          : Killed
Executable stack                         : Killed
Executable anonymous mapping (mprotect)  : Killed
Executable bss (mprotect)                : Killed
Executable data (mprotect)               : Killed
Executable heap (mprotect)               : Killed
Executable shared library bss (mprotect) : Killed
Executable shared library data (mprotect): Killed
Executable stack (mprotect)              : Killed
Anonymous mapping randomisation test     : 15 bits (guessed)
Heap randomisation test (ET_EXEC)        : 13 bits (guessed)
Heap randomisation test (ET_DYN)         : 23 bits (guessed)
Main executable randomisation (ET_EXEC)  : No randomisation
Main executable randomisation (ET_DYN)   : 15 bits (guessed)
Shared library randomisation test        : 15 bits (guessed)
Stack randomisation test (SEGMEXEC)      : 23 bits (guessed)
Stack randomisation test (PAGEEXEC)      : 23 bits (guessed)
Return to function (strcpy)              : Vulnerable
Return to function (strcpy, RANDEXEC)    : Vulnerable
Return to function (memcpy)              : Vulnerable
Return to function (memcpy, RANDEXEC)    : Vulnerable
Executable shared library bss            : Killed
Executable shared library data           : Killed
Writable text segments                   : Killed


I know that pax cannot protect against all of the return to function tests, but I have seem results here where some of the tests that my system is vulnerable to, others are not.

So my question is. Am I missing something?

I am running debian sarge, although with a vanilla 2.6.11.12 kernel patched with grsecurity. My kernel configuration is

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#
# Security options
#

#
# Grsecurity
#
CONFIG_GRKERNSEC=y
# CONFIG_GRKERNSEC_LOW is not set
# CONFIG_GRKERNSEC_MEDIUM is not set
# CONFIG_GRKERNSEC_HIGH is not set
CONFIG_GRKERNSEC_CUSTOM=y

#
# Address Space Protection
#
CONFIG_GRKERNSEC_KMEM=y
CONFIG_GRKERNSEC_IO=y
CONFIG_GRKERNSEC_PROC_MEMMAP=y
CONFIG_GRKERNSEC_BIGMEM=y
CONFIG_GRKERNSEC_BRUTE=y
CONFIG_GRKERNSEC_HIDESYM=y

#
# Role Based Access Control Options
#
CONFIG_GRKERNSEC_ACL_HIDEKERN=y
CONFIG_GRKERNSEC_ACL_MAXTRIES=3
CONFIG_GRKERNSEC_ACL_TIMEOUT=30

#
# Filesystem Protections
#
CONFIG_GRKERNSEC_PROC=y
CONFIG_GRKERNSEC_PROC_USER=y
CONFIG_GRKERNSEC_PROC_ADD=y
CONFIG_GRKERNSEC_LINK=y
CONFIG_GRKERNSEC_FIFO=y
CONFIG_GRKERNSEC_CHROOT=y
CONFIG_GRKERNSEC_CHROOT_MOUNT=y
CONFIG_GRKERNSEC_CHROOT_DOUBLE=y
CONFIG_GRKERNSEC_CHROOT_PIVOT=y
CONFIG_GRKERNSEC_CHROOT_CHDIR=y
CONFIG_GRKERNSEC_CHROOT_CHMOD=y
CONFIG_GRKERNSEC_CHROOT_FCHDIR=y
CONFIG_GRKERNSEC_CHROOT_MKNOD=y
CONFIG_GRKERNSEC_CHROOT_SHMAT=y
CONFIG_GRKERNSEC_CHROOT_UNIX=y
CONFIG_GRKERNSEC_CHROOT_FINDTASK=y
CONFIG_GRKERNSEC_CHROOT_NICE=y
CONFIG_GRKERNSEC_CHROOT_SYSCTL=y
CONFIG_GRKERNSEC_CHROOT_CAPS=y

#
# Kernel Auditing
#
# CONFIG_GRKERNSEC_AUDIT_GROUP is not set
# CONFIG_GRKERNSEC_EXECLOG is not set
# CONFIG_GRKERNSEC_RESLOG is not set
# CONFIG_GRKERNSEC_CHROOT_EXECLOG is not set
# CONFIG_GRKERNSEC_AUDIT_CHDIR is not set
# CONFIG_GRKERNSEC_AUDIT_MOUNT is not set
# CONFIG_GRKERNSEC_AUDIT_IPC is not set
# CONFIG_GRKERNSEC_SIGNAL is not set
# CONFIG_GRKERNSEC_FORKFAIL is not set
# CONFIG_GRKERNSEC_TIME is not set
# CONFIG_GRKERNSEC_PROC_IPADDR is not set
# CONFIG_GRKERNSEC_AUDIT_TEXTREL is not set

#
# Executable Protections
#
CONFIG_GRKERNSEC_EXECVE=y
CONFIG_GRKERNSEC_SHM=y
CONFIG_GRKERNSEC_DMESG=y
CONFIG_GRKERNSEC_RANDPID=y
# CONFIG_GRKERNSEC_TPE is not set

#
# Network Protections
#
CONFIG_GRKERNSEC_RANDNET=y
CONFIG_GRKERNSEC_RANDSRC=y
# CONFIG_GRKERNSEC_SOCKET is not set

#
# Sysctl support
#
# CONFIG_GRKERNSEC_SYSCTL is not set

#
# Logging Options
#
CONFIG_GRKERNSEC_FLOODTIME=10
CONFIG_GRKERNSEC_FLOODBURST=4

#
# PaX
#
CONFIG_PAX=y

#
# PaX Control
#
# CONFIG_PAX_SOFTMODE is not set
CONFIG_PAX_EI_PAX=y
# CONFIG_PAX_PT_PAX_FLAGS is not set
# CONFIG_PAX_NO_ACL_FLAGS is not set
CONFIG_PAX_HAVE_ACL_FLAGS=y
# CONFIG_PAX_HOOK_ACL_FLAGS is not set

#
# Non-executable pages
#
CONFIG_PAX_NOEXEC=y
CONFIG_PAX_SEGMEXEC=y
# CONFIG_PAX_EMUTRAMP is not set
CONFIG_PAX_MPROTECT=y
# CONFIG_PAX_NOELFRELOCS is not set

#
# Address Space Layout Randomization
#
CONFIG_PAX_ASLR=y
CONFIG_PAX_RANDKSTACK=y
CONFIG_PAX_RANDUSTACK=y
CONFIG_PAX_RANDMMAP=y
CONFIG_PAX_NOVSYSCALL=y
# CONFIG_KEYS is not set
# CONFIG_SECURITY is not set


Any comments?

Also, another question. What does it mean when paxtest says xx bits (guessed)?

Carceru wrote:I know that pax cannot protect against all of the return to function tests, but I have seem results here where some of the tests that my system is vulnerable to, others are not.

So my question is. Am I missing something?

RANDEXEC although don't lose much sleep over it, better use PIE for userland executable randomization (e.g., hardened gentoo).

Also, another question. What does it mean when paxtest says xx bits (guessed)?

xx is the amount of bits in the addresses that are random (i.e., different in each process). say, on i386 you have 32 bit addresses, of which xx can be randomized depending on the address region. you can run the get* paxtest binaries by hand to see them in action.