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Subject[PATCH 1/9] random32: introduce random32_get_bytes() and prandom32_get_bytes()
Date
Add functions to get the requested number of pseudo-random bytes.

The difference from get_random_bytes() is that it uses pseudo-random
numbers generated by random32. It is fast, suitable for generating
random bytes for testing, and reproducible if prandom32 interface is used.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Artem Bityutskiy <dedekind1@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: linux-mtd@lists.infradead.org
---
include/linux/random.h | 2 ++
lib/random32.c | 38 ++++++++++++++++++++++++++++++++++++++
2 files changed, 40 insertions(+)

diff --git a/include/linux/random.h b/include/linux/random.h
index 6330ed4..eedf429b 100644
--- a/include/linux/random.h
+++ b/include/linux/random.h
@@ -27,8 +27,10 @@ unsigned long randomize_range(unsigned long start, unsigned long end, unsigned l

u32 random32(void);
void srandom32(u32 seed);
+void random32_get_bytes(void *buf, int nbytes);

u32 prandom32(struct rnd_state *);
+void prandom32_get_bytes(struct rnd_state *state, void *buf, int nbytes);

/*
* Handle minimum values for seeds
diff --git a/lib/random32.c b/lib/random32.c
index 938bde5..aee87dd 100644
--- a/lib/random32.c
+++ b/lib/random32.c
@@ -61,6 +61,44 @@ u32 prandom32(struct rnd_state *state)
EXPORT_SYMBOL(prandom32);

/**
+ * prandom32_get_bytes - get the requested number of pseudo-random bytes
+ * @state: pointer to state structure holding seeded state.
+ * @buf: where to copy the pseudo-random bytes to
+ * @bytes: the requested number of bytes
+ *
+ * This is used for pseudo-randomness with no outside seeding.
+ * For more random results, use random32_get_bytes().
+ */
+void prandom32_get_bytes(struct rnd_state *state, void *buf, int bytes)
+{
+ unsigned char *p = buf;
+
+ for (; bytes > 0 && ((unsigned long)p) % sizeof(u32); bytes--, p++)
+ *p = prandom32(state);
+
+ for (; bytes > sizeof(u32) - 1; bytes -= sizeof(u32), p += sizeof(u32))
+ *(u32 *)p = prandom32(state);
+
+ for (; bytes > 0; bytes--, p++)
+ *p = prandom32(state);
+}
+EXPORT_SYMBOL(prandom32_get_bytes);
+
+/**
+ * random32_get_bytes - get the requested number of pseudo-random bytes
+ * @buf: where to copy the pseudo-random bytes to
+ * @bytes: the requested number of bytes
+ */
+void random32_get_bytes(void *buf, int bytes)
+{
+ struct rnd_state *state = &get_cpu_var(net_rand_state);
+
+ prandom32_get_bytes(state, buf, bytes);
+ put_cpu_var(state);
+}
+EXPORT_SYMBOL(random32_get_bytes);
+
+/**
* random32 - pseudo random number generator
*
* A 32 bit pseudo-random number is generated using a fast
--
1.7.11.7


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