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author | Jason A. Donenfeld <Jason@zx2c4.com> | 2022-06-01 23:45:33 +0300 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-02-25 13:51:50 +0300 |
commit | e4935368448ce8097dada35163598e93567f1110 (patch) | |
tree | abbc2ab3f71a98b45919560417c81b75693335a9 | |
parent | c30e4cc30aeca519e82babfa1f05bfcf146b654b (diff) | |
download | linux-e4935368448ce8097dada35163598e93567f1110.tar.xz |
random: always mix cycle counter in add_latent_entropy()
[ Upstream commit d7bf7f3b813e3755226bcb5114ad2ac477514ebf ]
add_latent_entropy() is called every time a process forks, in
kernel_clone(). This in turn calls add_device_randomness() using the
latent entropy global state. add_device_randomness() does two things:
2) Mixes into the input pool the latent entropy argument passed; and
1) Mixes in a cycle counter, a sort of measurement of when the event
took place, the high precision bits of which are presumably
difficult to predict.
(2) is impossible without CONFIG_GCC_PLUGIN_LATENT_ENTROPY=y. But (1) is
always possible. However, currently CONFIG_GCC_PLUGIN_LATENT_ENTROPY=n
disables both (1) and (2), instead of just (2).
This commit causes the CONFIG_GCC_PLUGIN_LATENT_ENTROPY=n case to still
do (1) by passing NULL (len 0) to add_device_randomness() when add_latent_
entropy() is called.
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: PaX Team <pageexec@freemail.hu>
Cc: Emese Revfy <re.emese@gmail.com>
Fixes: 38addce8b600 ("gcc-plugins: Add latent_entropy plugin")
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
-rw-r--r-- | include/linux/random.h | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/include/linux/random.h b/include/linux/random.h index 3feafab498ad..ed75fb2b0ca9 100644 --- a/include/linux/random.h +++ b/include/linux/random.h @@ -19,14 +19,14 @@ void add_input_randomness(unsigned int type, unsigned int code, void add_interrupt_randomness(int irq) __latent_entropy; void add_hwgenerator_randomness(const void *buf, size_t len, size_t entropy); -#if defined(LATENT_ENTROPY_PLUGIN) && !defined(__CHECKER__) static inline void add_latent_entropy(void) { +#if defined(LATENT_ENTROPY_PLUGIN) && !defined(__CHECKER__) add_device_randomness((const void *)&latent_entropy, sizeof(latent_entropy)); -} #else -static inline void add_latent_entropy(void) { } + add_device_randomness(NULL, 0); #endif +} void get_random_bytes(void *buf, size_t len); size_t __must_check get_random_bytes_arch(void *buf, size_t len); |