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authorTheodore Ts'o <tytso@mit.edu>2017-06-08 11:16:59 +0300
committerTheodore Ts'o <tytso@mit.edu>2017-07-15 19:19:28 +0300
commiteecabf567422eda02bd179f2707d8fe24f52d888 (patch)
tree621859908bc9613fa913338d513785072d07ae93 /lib
parentd06bfd1989fe97623b32d6df4ffa6e4338c99dc8 (diff)
downloadlinux-eecabf567422eda02bd179f2707d8fe24f52d888.tar.xz
random: suppress spammy warnings about unseeded randomness
Unfortunately, on some models of some architectures getting a fully seeded CRNG is extremely difficult, and so this can result in dmesg getting spammed for a surprisingly long time. This is really bad from a security perspective, and so architecture maintainers really need to do what they can to get the CRNG seeded sooner after the system is booted. However, users can't do anything actionble to address this, and spamming the kernel messages log will only just annoy people. For developers who want to work on improving this situation, CONFIG_WARN_UNSEEDED_RANDOM has been renamed to CONFIG_WARN_ALL_UNSEEDED_RANDOM. By default the kernel will always print the first use of unseeded randomness. This way, hopefully the security obsessed will be happy that there is _some_ indication when the kernel boots there may be a potential issue with that architecture or subarchitecture. To see all uses of unseeded randomness, developers can enable CONFIG_WARN_ALL_UNSEEDED_RANDOM. Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'lib')
-rw-r--r--lib/Kconfig.debug24
1 files changed, 18 insertions, 6 deletions
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index c4159605bfbf..9d0a244074b9 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1209,10 +1209,9 @@ config STACKTRACE
It is also used by various kernel debugging features that require
stack trace generation.
-config WARN_UNSEEDED_RANDOM
- bool "Warn when kernel uses unseeded randomness"
- default y
- depends on DEBUG_KERNEL
+config WARN_ALL_UNSEEDED_RANDOM
+ bool "Warn for all uses of unseeded randomness"
+ default n
help
Some parts of the kernel contain bugs relating to their use of
cryptographically secure random numbers before it's actually possible
@@ -1222,8 +1221,21 @@ config WARN_UNSEEDED_RANDOM
are going wrong, so that they might contact developers about fixing
it.
- Say Y here, unless you simply do not care about using unseeded
- randomness and do not want a potential warning message in your logs.
+ Unfortunately, on some models of some architectures getting
+ a fully seeded CRNG is extremely difficult, and so this can
+ result in dmesg getting spammed for a surprisingly long
+ time. This is really bad from a security perspective, and
+ so architecture maintainers really need to do what they can
+ to get the CRNG seeded sooner after the system is booted.
+ However, since users can not do anything actionble to
+ address this, by default the kernel will issue only a single
+ warning for the first use of unseeded randomness.
+
+ Say Y here if you want to receive warnings for all uses of
+ unseeded randomness. This will be of use primarily for
+ those developers interersted in improving the security of
+ Linux kernels running on their architecture (or
+ subarchitecture).
config DEBUG_KOBJECT
bool "kobject debugging"