linux/security/Kconfig
maximilian attems 5f46ce14bd security: enhance DEFAULT_MMAP_MIN_ADDR description
Got burned by setting the proposed default of 65536
across all Debian archs.

Thus proposing to be more specific on which archs you may
set this. Also propose a value for arm and friends that
doesn't break sshd.

Reword to mention working archs ia64 and ppc64 too.

Signed-off-by: maximilian attems <max@stro.at>
Cc: Martin Michlmayr <tbm@cyrius.com>
Cc: Gordon Farquharson <gordonfarquharson@gmail.com>
Acked-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
2008-04-18 20:26:18 +10:00

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#
# Security configuration
#
menu "Security options"
config KEYS
bool "Enable access key retention support"
help
This option provides support for retaining authentication tokens and
access keys in the kernel.
It also includes provision of methods by which such keys might be
associated with a process so that network filesystems, encryption
support and the like can find them.
Furthermore, a special type of key is available that acts as keyring:
a searchable sequence of keys. Each process is equipped with access
to five standard keyrings: UID-specific, GID-specific, session,
process and thread.
If you are unsure as to whether this is required, answer N.
config KEYS_DEBUG_PROC_KEYS
bool "Enable the /proc/keys file by which keys may be viewed"
depends on KEYS
help
This option turns on support for the /proc/keys file - through which
can be listed all the keys on the system that are viewable by the
reading process.
The only keys included in the list are those that grant View
permission to the reading process whether or not it possesses them.
Note that LSM security checks are still performed, and may further
filter out keys that the current process is not authorised to view.
Only key attributes are listed here; key payloads are not included in
the resulting table.
If you are unsure as to whether this is required, answer N.
config SECURITY
bool "Enable different security models"
depends on SYSFS
help
This allows you to choose different security modules to be
configured into your kernel.
If this option is not selected, the default Linux security
model will be used.
If you are unsure how to answer this question, answer N.
config SECURITY_NETWORK
bool "Socket and Networking Security Hooks"
depends on SECURITY
help
This enables the socket and networking security hooks.
If enabled, a security module can use these hooks to
implement socket and networking access controls.
If you are unsure how to answer this question, answer N.
config SECURITY_NETWORK_XFRM
bool "XFRM (IPSec) Networking Security Hooks"
depends on XFRM && SECURITY_NETWORK
help
This enables the XFRM (IPSec) networking security hooks.
If enabled, a security module can use these hooks to
implement per-packet access controls based on labels
derived from IPSec policy. Non-IPSec communications are
designated as unlabelled, and only sockets authorized
to communicate unlabelled data can send without using
IPSec.
If you are unsure how to answer this question, answer N.
config SECURITY_CAPABILITIES
bool "Default Linux Capabilities"
depends on SECURITY
default y
help
This enables the "default" Linux capabilities functionality.
If you are unsure how to answer this question, answer Y.
config SECURITY_FILE_CAPABILITIES
bool "File POSIX Capabilities (EXPERIMENTAL)"
depends on (SECURITY=n || SECURITY_CAPABILITIES!=n) && EXPERIMENTAL
default n
help
This enables filesystem capabilities, allowing you to give
binaries a subset of root's powers without using setuid 0.
If in doubt, answer N.
config SECURITY_ROOTPLUG
bool "Root Plug Support"
depends on USB=y && SECURITY
help
This is a sample LSM module that should only be used as such.
It prevents any programs running with egid == 0 if a specific
USB device is not present in the system.
See <http://www.linuxjournal.com/article.php?sid=6279> for
more information about this module.
If you are unsure how to answer this question, answer N.
config SECURITY_DEFAULT_MMAP_MIN_ADDR
int "Low address space to protect from user allocation"
depends on SECURITY
default 0
help
This is the portion of low virtual memory which should be protected
from userspace allocation. Keeping a user from writing to low pages
can help reduce the impact of kernel NULL pointer bugs.
For most ia64, ppc64 and x86 users with lots of address space
a value of 65536 is reasonable and should cause no problems.
On arm and other archs it should not be higher than 32768.
Programs which use vm86 functionality would either need additional
permissions from either the LSM or the capabilities module or have
this protection disabled.
This value can be changed after boot using the
/proc/sys/vm/mmap_min_addr tunable.
source security/selinux/Kconfig
source security/smack/Kconfig
endmenu