ec9ee4acd9
Commit d07e22597d1d ("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.
This patch (of 2):
Add get_random_long().
Signed-off-by: Daniel Cashman <dcashman@android.com>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: David S. Miller <davem@davemloft.net>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Nick Kralevich <nnk@google.com>
Cc: Jeff Vander Stoep <jeffv@google.com>
Cc: Mark Salyzyn <salyzyn@android.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
132 lines
3.4 KiB
C
132 lines
3.4 KiB
C
/*
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* include/linux/random.h
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*
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* Include file for the random number generator.
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*/
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#ifndef _LINUX_RANDOM_H
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#define _LINUX_RANDOM_H
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#include <linux/list.h>
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#include <linux/once.h>
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#include <uapi/linux/random.h>
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struct random_ready_callback {
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struct list_head list;
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void (*func)(struct random_ready_callback *rdy);
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struct module *owner;
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};
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extern void add_device_randomness(const void *, unsigned int);
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extern void add_input_randomness(unsigned int type, unsigned int code,
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unsigned int value);
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extern void add_interrupt_randomness(int irq, int irq_flags);
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extern void get_random_bytes(void *buf, int nbytes);
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extern int add_random_ready_callback(struct random_ready_callback *rdy);
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extern void del_random_ready_callback(struct random_ready_callback *rdy);
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extern void get_random_bytes_arch(void *buf, int nbytes);
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void generate_random_uuid(unsigned char uuid_out[16]);
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extern int random_int_secret_init(void);
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#ifndef MODULE
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extern const struct file_operations random_fops, urandom_fops;
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#endif
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unsigned int get_random_int(void);
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unsigned long get_random_long(void);
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unsigned long randomize_range(unsigned long start, unsigned long end, unsigned long len);
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u32 prandom_u32(void);
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void prandom_bytes(void *buf, size_t nbytes);
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void prandom_seed(u32 seed);
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void prandom_reseed_late(void);
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struct rnd_state {
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__u32 s1, s2, s3, s4;
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};
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u32 prandom_u32_state(struct rnd_state *state);
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void prandom_bytes_state(struct rnd_state *state, void *buf, size_t nbytes);
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void prandom_seed_full_state(struct rnd_state __percpu *pcpu_state);
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#define prandom_init_once(pcpu_state) \
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DO_ONCE(prandom_seed_full_state, (pcpu_state))
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/**
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* prandom_u32_max - returns a pseudo-random number in interval [0, ep_ro)
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* @ep_ro: right open interval endpoint
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*
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* Returns a pseudo-random number that is in interval [0, ep_ro). Note
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* that the result depends on PRNG being well distributed in [0, ~0U]
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* u32 space. Here we use maximally equidistributed combined Tausworthe
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* generator, that is, prandom_u32(). This is useful when requesting a
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* random index of an array containing ep_ro elements, for example.
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*
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* Returns: pseudo-random number in interval [0, ep_ro)
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*/
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static inline u32 prandom_u32_max(u32 ep_ro)
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{
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return (u32)(((u64) prandom_u32() * ep_ro) >> 32);
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}
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/*
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* Handle minimum values for seeds
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*/
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static inline u32 __seed(u32 x, u32 m)
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{
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return (x < m) ? x + m : x;
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}
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/**
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* prandom_seed_state - set seed for prandom_u32_state().
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* @state: pointer to state structure to receive the seed.
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* @seed: arbitrary 64-bit value to use as a seed.
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*/
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static inline void prandom_seed_state(struct rnd_state *state, u64 seed)
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{
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u32 i = (seed >> 32) ^ (seed << 10) ^ seed;
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state->s1 = __seed(i, 2U);
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state->s2 = __seed(i, 8U);
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state->s3 = __seed(i, 16U);
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state->s4 = __seed(i, 128U);
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}
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#ifdef CONFIG_ARCH_RANDOM
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# include <asm/archrandom.h>
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#else
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static inline int arch_get_random_long(unsigned long *v)
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{
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return 0;
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}
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static inline int arch_get_random_int(unsigned int *v)
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{
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return 0;
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}
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static inline int arch_has_random(void)
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{
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return 0;
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}
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static inline int arch_get_random_seed_long(unsigned long *v)
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{
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return 0;
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}
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static inline int arch_get_random_seed_int(unsigned int *v)
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{
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return 0;
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}
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static inline int arch_has_random_seed(void)
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{
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return 0;
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}
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#endif
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/* Pseudo random number generator from numerical recipes. */
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static inline u32 next_pseudo_random32(u32 seed)
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{
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return seed * 1664525 + 1013904223;
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}
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#endif /* _LINUX_RANDOM_H */
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