diff options
| author | dcashman <dcashman@google.com> | 2016-02-24 13:27:06 -0800 |
|---|---|---|
| committer | Kees Cook <keescook@google.com> | 2016-03-24 15:32:08 -0700 |
| commit | 1a788b5faf8a936314a4f18fef36833a04527759 (patch) | |
| tree | 38e2aaa4ad78f96ee3c61b85d3850ca72fe38ef7 /include/linux/random.h | |
| parent | 113b124387d69a2771fbd80cb8155d556ba0f60b (diff) | |
| download | edison-v3.10-1a788b5faf8a936314a4f18fef36833a04527759.tar.gz | |
FROMLIST: drivers: char: random: add get_random_long()
(cherry picked from commit https://lkml.org/lkml/2016/2/4/831)
d07e22597d1d355 ("mm: mmap: add new /proc tunable for mmap_base ASLR")
added the ability to choose from a range of values to use for entropy
count in generating the random offset to the mmap_base address. The
maximum value on this range was set to 32 bits for 64-bit x86 systems, but
this value could be increased further, requiring more than the 32 bits of
randomness provided by get_random_int(), as is already possible for arm64.
Add a new function: get_random_long() which more naturally fits with the
mmap usage of get_random_int() but operates exactly the same as
get_random_int().
Also, fix the shifting constant in mmap_rnd() to be an unsigned long so
that values greater than 31 bits generate an appropriate mask without
overflow. This is especially important on x86, as its shift instruction
uses a 5-bit mask for the shift operand, which meant that any value for
mmap_rnd_bits over 31 acts as a no-op and effectively disables mmap_base
randomization.
Finally, replace calls to get_random_int() with get_random_long() where
appropriate.
Signed-off-by: Daniel Cashman <dcashman@android.com>
Signed-off-by: Daniel Cashman <dcashman@google.com>
Bug: 27796957
Patchset: ASLR sysctl
Change-Id: Ifd46298e517b522deb1fedb64109acb7b7bdbc19
Signed-off-by: Kees Cook <keescook@google.com>
Diffstat (limited to 'include/linux/random.h')
| -rw-r--r-- | include/linux/random.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/random.h b/include/linux/random.h index bf9085e89fb..1b91d7d186e 100644 --- a/include/linux/random.h +++ b/include/linux/random.h @@ -24,6 +24,7 @@ extern const struct file_operations random_fops, urandom_fops; #endif unsigned int get_random_int(void); +unsigned long get_random_long(void); unsigned long randomize_range(unsigned long start, unsigned long end, unsigned long len); u32 prandom_u32(void); |