Subject: Re: [vserver] Kernel bug
From:Łukasz Czarniecki <luqe@sanki.roteh.pl>
Date: Tue, 12 Feb 2008 14:49:10 +0100

Natanael Copa wrote:
> BTW... the exploit thats out for this bug didnt work on the
> vserver-grsecurity kernel. A day like this I'm happy I'm using it. 

Hi

I'm using 2.6.22.15-grsec2.1.11-vs2.2.0.5 kernel.
And the exploit works in both vserver and host.

It doesn't let to escape from vserver but it could be possible
according to http://www.debian.org/security/2008/dsa-1494
"In the vserver-enabled kernels, a missing access check on certain 
symlinks in /proc enabled local attackers to access resources in other 
vservers"

Did you just set TPE or some other options?
Which grsecurity option protects against this exploit?
Can you share your config?

Lukasz Czarniecki

Here is my config:
#
# Kernel hacking
#
CONFIG_TRACE_IRQFLAGS_SUPPORT=y
CONFIG_PRINTK_TIME=y
CONFIG_ENABLE_MUST_CHECK=y
CONFIG_MAGIC_SYSRQ=y
CONFIG_UNUSED_SYMBOLS=y
CONFIG_DEBUG_FS=y
# CONFIG_HEADERS_CHECK is not set
CONFIG_DEBUG_KERNEL=y
# CONFIG_DEBUG_SHIRQ is not set
CONFIG_DETECT_SOFTLOCKUP=y
# CONFIG_SCHEDSTATS is not set
# CONFIG_TIMER_STATS is not set
# CONFIG_DEBUG_SLAB is not set
# CONFIG_DEBUG_RT_MUTEXES is not set
# CONFIG_RT_MUTEX_TESTER is not set
# CONFIG_DEBUG_SPINLOCK is not set
# CONFIG_DEBUG_MUTEXES is not set
# CONFIG_DEBUG_LOCK_ALLOC is not set
# CONFIG_PROVE_LOCKING is not set
# CONFIG_DEBUG_SPINLOCK_SLEEP is not set
# CONFIG_DEBUG_LOCKING_API_SELFTESTS is not set
# CONFIG_DEBUG_KOBJECT is not set
CONFIG_DEBUG_BUGVERBOSE=y
# CONFIG_DEBUG_INFO is not set
# CONFIG_DEBUG_VM is not set
# CONFIG_DEBUG_LIST is not set
# CONFIG_FRAME_POINTER is not set
# CONFIG_FORCED_INLINING is not set
# CONFIG_RCU_TORTURE_TEST is not set
# CONFIG_FAULT_INJECTION is not set
# CONFIG_DEBUG_RODATA is not set
# CONFIG_IOMMU_DEBUG is not set
# CONFIG_DEBUG_STACKOVERFLOW is not set
# CONFIG_DEBUG_STACK_USAGE is not set

#
# Linux VServer
#
# CONFIG_VSERVER_LEGACY is not set
# CONFIG_VSERVER_LEGACYNET is not set
CONFIG_VSERVER_REMAP_SADDR=y
CONFIG_VSERVER_COWBL=y
# CONFIG_VSERVER_VTIME is not set
CONFIG_VSERVER_PROC_SECURE=y
CONFIG_VSERVER_HARDCPU=y
CONFIG_VSERVER_IDLETIME=y
CONFIG_VSERVER_IDLELIMIT=y
# CONFIG_TAGGING_NONE is not set
# CONFIG_TAGGING_UID16 is not set
# CONFIG_TAGGING_GID16 is not set
CONFIG_TAGGING_ID24=y
# CONFIG_TAGGING_INTERN is not set
# CONFIG_TAG_NFSD is not set
CONFIG_PROPAGATE=y
CONFIG_VSERVER_PRIVACY=y
CONFIG_VSERVER_CONTEXTS=768
CONFIG_VSERVER_WARN=y
CONFIG_VSERVER_DEBUG=y
CONFIG_VSERVER_HISTORY=y
CONFIG_VSERVER_HISTORY_SIZE=64
# CONFIG_VSERVER_MONITOR is not set
CONFIG_VSERVER=y
CONFIG_VSERVER_NGNET=y

#
# 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_BRUTE=y
CONFIG_GRKERNSEC_MODSTOP=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 is not set
# CONFIG_GRKERNSEC_CHROOT_DOUBLE is not set
CONFIG_GRKERNSEC_CHROOT_PIVOT=y
# CONFIG_GRKERNSEC_CHROOT_CHDIR is not set
# CONFIG_GRKERNSEC_CHROOT_CHMOD is not set
CONFIG_GRKERNSEC_CHROOT_FCHDIR=y
CONFIG_GRKERNSEC_CHROOT_MKNOD=y
CONFIG_GRKERNSEC_CHROOT_SHMAT=y
CONFIG_GRKERNSEC_CHROOT_UNIX=y
# CONFIG_GRKERNSEC_CHROOT_FINDTASK is not set
CONFIG_GRKERNSEC_CHROOT_NICE=y
CONFIG_GRKERNSEC_CHROOT_SYSCTL=y
# CONFIG_GRKERNSEC_CHROOT_CAPS is not set

#
# Kernel Auditing
#
# CONFIG_GRKERNSEC_AUDIT_GROUP is not set
# CONFIG_GRKERNSEC_EXECLOG is not set
CONFIG_GRKERNSEC_RESLOG=y
# 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=y
CONFIG_GRKERNSEC_FORKFAIL=y
CONFIG_GRKERNSEC_TIME=y
CONFIG_GRKERNSEC_PROC_IPADDR=y
# CONFIG_GRKERNSEC_AUDIT_TEXTREL is not set

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

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

#
# Sysctl support
#
CONFIG_GRKERNSEC_SYSCTL=y
CONFIG_GRKERNSEC_SYSCTL_ON=y

#
# Logging Options
#
CONFIG_GRKERNSEC_FLOODTIME=10
CONFIG_GRKERNSEC_FLOODBURST=4

#
# PaX
#
CONFIG_PAX=y

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

#
# Non-executable pages
#
CONFIG_PAX_NOEXEC=y
CONFIG_PAX_PAGEEXEC=y
CONFIG_PAX_MPROTECT=y
CONFIG_PAX_NOELFRELOCS=y

#
# Address Space Layout Randomization
#
CONFIG_PAX_ASLR=y
CONFIG_PAX_RANDUSTACK=y
CONFIG_PAX_RANDMMAP=y

#
# Miscellaneous hardening features
#
CONFIG_PAX_MEMORY_SANITIZE=y
CONFIG_KEYS=y
# CONFIG_KEYS_DEBUG_PROC_KEYS is not set
# CONFIG_SECURITY is not set