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6f8746868e
(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. Bug: 26963541 Signed-off-by: Daniel Cashman <dcashman@android.com> Signed-off-by: Daniel Cashman <dcashman@google.com> Change-Id: Ie7552631b5db86f3482cf15e7dc916d89c1c502b
130 lines
3.1 KiB
C
130 lines
3.1 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/types.h>
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#include <linux/ioctl.h>
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#include <linux/irqnr.h>
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/* ioctl()'s for the random number generator */
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/* Get the entropy count. */
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#define RNDGETENTCNT _IOR( 'R', 0x00, int )
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/* Add to (or subtract from) the entropy count. (Superuser only.) */
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#define RNDADDTOENTCNT _IOW( 'R', 0x01, int )
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/* Get the contents of the entropy pool. (Superuser only.) */
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#define RNDGETPOOL _IOR( 'R', 0x02, int [2] )
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/*
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* Write bytes into the entropy pool and add to the entropy count.
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* (Superuser only.)
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*/
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#define RNDADDENTROPY _IOW( 'R', 0x03, int [2] )
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/* Clear entropy count to 0. (Superuser only.) */
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#define RNDZAPENTCNT _IO( 'R', 0x04 )
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/* Clear the entropy pool and associated counters. (Superuser only.) */
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#define RNDCLEARPOOL _IO( 'R', 0x06 )
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struct rand_pool_info {
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int entropy_count;
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int buf_size;
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__u32 buf[0];
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};
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struct rnd_state {
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__u32 s1, s2, s3;
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};
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/* Exported functions */
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/*
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* Flags for getrandom(2)
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*
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* GRND_NONBLOCK Don't block and return EAGAIN instead
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* GRND_RANDOM Use the /dev/random pool instead of /dev/urandom
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*/
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#define GRND_NONBLOCK 0x0001
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#define GRND_RANDOM 0x0002
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#ifdef __KERNEL__
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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 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, int nbytes);
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void prandom_seed(u32 seed);
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void prandom_reseed_late(void);
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/*
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* These macros are preserved for backward compatibility and should be
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* removed as soon as a transition is finished.
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*/
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#define random32() prandom_u32()
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#define srandom32(seed) prandom_seed(seed)
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u32 prandom_u32_state(struct rnd_state *);
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void prandom_bytes_state(struct rnd_state *state, void *buf, int nbytes);
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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, 2);
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state->s2 = __seed(i, 8);
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state->s3 = __seed(i, 16);
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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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#endif
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#endif /* __KERNEL___ */
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#endif /* _LINUX_RANDOM_H */
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