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Rik van Riel 022c204040 random,stackprotect: introduce get_random_canary function
Patch series "stackprotector: ascii armor the stack canary", v2.

Zero out the first byte of the stack canary value on 64 bit systems, in
order to mitigate unterminated C string overflows.

The null byte both prevents C string functions from reading the canary,
and from writing it if the canary value were guessed or obtained through
some other means.

Reducing the entropy by 8 bits is acceptable on 64-bit systems, which
will still have 56 bits of entropy left, but not on 32 bit systems, so
the "ascii armor" canary is only implemented on 64-bit systems.

Inspired by the "ascii armor" code in execshield and Daniel Micay's
linux-hardened tree.

Also see https://github.com/thestinger/linux-hardened/

This patch (of 5):

Introduce get_random_canary(), which provides a random unsigned long
canary value with the first byte zeroed out on 64 bit architectures, in
order to mitigate non-terminated C string overflows.

The null byte both prevents C string functions from reading the canary,
and from writing it if the canary value were guessed or obtained through
some other means.

Reducing the entropy by 8 bits is acceptable on 64-bit systems, which
will still have 56 bits of entropy left, but not on 32 bit systems, so
the "ascii armor" canary is only implemented on 64-bit systems.

Inspired by the "ascii armor" code in the old execshield patches, and
Daniel Micay's linux-hardened tree.

Link: http://lkml.kernel.org/r/20170524155751.424-2-riel@redhat.com
Signed-off-by: Rik van Riel <riel@redhat.com>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Daniel Micay <danielmicay@gmail.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-12 16:26:03 -07:00
arch sh: mark end of BUG() implementation as unreachable 2017-07-12 16:26:03 -07:00
block
certs
crypto
Documentation fault-inject: support systematic fault injection 2017-07-12 16:26:01 -07:00
drivers IB/rxe: do not copy extra stack memory to skb 2017-07-12 16:26:03 -07:00
firmware
fs fault-inject: support systematic fault injection 2017-07-12 16:26:01 -07:00
include random,stackprotect: introduce get_random_canary function 2017-07-12 16:26:03 -07:00
init random: do not ignore early device randomness 2017-07-12 16:26:00 -07:00
ipc ipc/util.h: update documentation for ipc_getref() and ipc_putref() 2017-07-12 16:26:02 -07:00
kernel kexec_file: adjust declaration of kexec_purgatory 2017-07-12 16:26:02 -07:00
lib include/linux/string.h: add the option of fortified string.h functions 2017-07-12 16:26:03 -07:00
mm
net net/netfilter/x_tables.c: use kvmalloc() in xt_alloc_table_info() 2017-07-12 16:26:02 -07:00
samples kfifo: clean up example to not use page_link 2017-07-12 16:26:01 -07:00
scripts scripts/gdb: lx-dmesg: use explicit encoding=utf8 errors=replace 2017-07-12 16:26:01 -07:00
security include/linux/string.h: add the option of fortified string.h functions 2017-07-12 16:26:03 -07:00
sound
tools test_sysctl: test against int proc_dointvec() array support 2017-07-12 16:26:00 -07:00
usr
virt
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.get_maintainer.ignore
.gitattributes
.gitignore
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README

Linux kernel
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