diff --git a/drivers/char/random.c b/drivers/char/random.c index 6da3f250804c9339b2b399ffd9db3d88252ffbab..84c576ec20e907b078c8d8a8be9b0356f2d8db6d 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -255,6 +255,7 @@ #include #include #include +#include #ifdef CONFIG_GENERIC_HARDIRQS # include @@ -302,7 +303,7 @@ static int random_read_wakeup_thresh = 64; * should wake up processes which are selecting or polling on write * access to /dev/random. */ -static int random_write_wakeup_thresh = 128; +static int random_write_wakeup_thresh = 28 * OUTPUT_POOL_WORDS; /* * The minimum number of seconds between urandom pool resending. We @@ -428,6 +429,7 @@ struct entropy_store { __u32 *pool; const char *name; struct entropy_store *pull; + struct work_struct push_work; /* read-write data: */ unsigned long last_pulled; @@ -442,6 +444,7 @@ struct entropy_store { __u8 last_data[EXTRACT_SIZE]; }; +static void push_to_pool(struct work_struct *work); static __u32 input_pool_data[INPUT_POOL_WORDS]; static __u32 blocking_pool_data[OUTPUT_POOL_WORDS]; static __u32 nonblocking_pool_data[OUTPUT_POOL_WORDS]; @@ -460,7 +463,9 @@ static struct entropy_store blocking_pool = { .limit = 1, .pull = &input_pool, .lock = __SPIN_LOCK_UNLOCKED(blocking_pool.lock), - .pool = blocking_pool_data + .pool = blocking_pool_data, + .push_work = __WORK_INITIALIZER(blocking_pool.push_work, + push_to_pool), }; static struct entropy_store nonblocking_pool = { @@ -468,7 +473,9 @@ static struct entropy_store nonblocking_pool = { .name = "nonblocking", .pull = &input_pool, .lock = __SPIN_LOCK_UNLOCKED(nonblocking_pool.lock), - .pool = nonblocking_pool_data + .pool = nonblocking_pool_data, + .push_work = __WORK_INITIALIZER(nonblocking_pool.push_work, + push_to_pool), }; static __u32 const twist_table[8] = { @@ -655,21 +662,48 @@ static void credit_entropy_bits(struct entropy_store *r, int nbits) if (cmpxchg(&r->entropy_count, orig, entropy_count) != orig) goto retry; + r->entropy_total += nbits; if (!r->initialized && nbits > 0) { - r->entropy_total += nbits; - if (r->entropy_total > 128) + if (r->entropy_total > 128) { r->initialized = 1; + r->entropy_total = 0; + } } trace_credit_entropy_bits(r->name, nbits, entropy_count >> ENTROPY_SHIFT, r->entropy_total, _RET_IP_); - /* should we wake readers? */ - if (r == &input_pool && - (entropy_count >> ENTROPY_SHIFT) >= random_read_wakeup_thresh) { - wake_up_interruptible(&random_read_wait); - kill_fasync(&fasync, SIGIO, POLL_IN); + if (r == &input_pool) { + int entropy_bytes = entropy_count >> ENTROPY_SHIFT; + + /* should we wake readers? */ + if (entropy_bytes >= random_read_wakeup_thresh) { + wake_up_interruptible(&random_read_wait); + kill_fasync(&fasync, SIGIO, POLL_IN); + } + /* If the input pool is getting full, send some + * entropy to the two output pools, flipping back and + * forth between them, until the output pools are 75% + * full. + */ + if (entropy_bytes > random_write_wakeup_thresh && + r->initialized && + r->entropy_total >= 2*random_read_wakeup_thresh) { + static struct entropy_store *last = &blocking_pool; + struct entropy_store *other = &blocking_pool; + + if (last == &blocking_pool) + other = &nonblocking_pool; + if (other->entropy_count <= + 3 * other->poolinfo->poolfracbits / 4) + last = other; + if (last->entropy_count <= + 3 * last->poolinfo->poolfracbits / 4) { + schedule_work(&last->push_work); + r->entropy_total = 0; + } + } } } @@ -877,10 +911,9 @@ static ssize_t extract_entropy(struct entropy_store *r, void *buf, * from the primary pool to the secondary extraction pool. We make * sure we pull enough for a 'catastrophic reseed'. */ +static void _xfer_secondary_pool(struct entropy_store *r, size_t nbytes); static void xfer_secondary_pool(struct entropy_store *r, size_t nbytes) { - __u32 tmp[OUTPUT_POOL_WORDS]; - if (r->limit == 0 && random_min_urandom_seed) { unsigned long now = jiffies; @@ -891,26 +924,47 @@ static void xfer_secondary_pool(struct entropy_store *r, size_t nbytes) } if (r->pull && r->entropy_count < (nbytes << (ENTROPY_SHIFT + 3)) && - r->entropy_count < r->poolinfo->poolfracbits) { - /* If we're limited, always leave two wakeup worth's BITS */ - int rsvd = r->limit ? 0 : random_read_wakeup_thresh/4; - int bytes = nbytes; - - /* pull at least as many as BYTES as wakeup BITS */ - bytes = max_t(int, bytes, random_read_wakeup_thresh / 8); - /* but never more than the buffer size */ - bytes = min_t(int, bytes, sizeof(tmp)); - - DEBUG_ENT("going to reseed %s with %d bits " - "(%zu of %d requested)\n", - r->name, bytes * 8, nbytes * 8, - r->entropy_count >> ENTROPY_SHIFT); - - bytes = extract_entropy(r->pull, tmp, bytes, - random_read_wakeup_thresh / 8, rsvd); - mix_pool_bytes(r, tmp, bytes, NULL); - credit_entropy_bits(r, bytes*8); - } + r->entropy_count < r->poolinfo->poolfracbits) + _xfer_secondary_pool(r, nbytes); +} + +static void _xfer_secondary_pool(struct entropy_store *r, size_t nbytes) +{ + __u32 tmp[OUTPUT_POOL_WORDS]; + + /* For /dev/random's pool, always leave two wakeup worth's BITS */ + int rsvd = r->limit ? 0 : random_read_wakeup_thresh/4; + int bytes = nbytes; + + /* pull at least as many as BYTES as wakeup BITS */ + bytes = max_t(int, bytes, random_read_wakeup_thresh / 8); + /* but never more than the buffer size */ + bytes = min_t(int, bytes, sizeof(tmp)); + + DEBUG_ENT("going to reseed %s with %d bits (%zu of %d requested)\n", + r->name, bytes * 8, nbytes * 8, + r->entropy_count >> ENTROPY_SHIFT); + + bytes = extract_entropy(r->pull, tmp, bytes, + random_read_wakeup_thresh / 8, rsvd); + mix_pool_bytes(r, tmp, bytes, NULL); + credit_entropy_bits(r, bytes*8); +} + +/* + * Used as a workqueue function so that when the input pool is getting + * full, we can "spill over" some entropy to the output pools. That + * way the output pools can store some of the excess entropy instead + * of letting it go to waste. + */ +static void push_to_pool(struct work_struct *work) +{ + struct entropy_store *r = container_of(work, struct entropy_store, + push_work); + BUG_ON(!r); + _xfer_secondary_pool(r, random_read_wakeup_thresh/8); + trace_push_to_pool(r->name, r->entropy_count >> ENTROPY_SHIFT, + r->pull->entropy_count >> ENTROPY_SHIFT); } /* diff --git a/include/trace/events/random.h b/include/trace/events/random.h index 2ffcaec5860a36f6597aed339eeb3c226e2ab772..527b5dc1b4166a981dd34ec732e123b5a851b0ce 100644 --- a/include/trace/events/random.h +++ b/include/trace/events/random.h @@ -87,6 +87,28 @@ TRACE_EVENT(credit_entropy_bits, (void *)__entry->IP) ); +TRACE_EVENT(push_to_pool, + TP_PROTO(const char *pool_name, int pool_bits, int input_bits), + + TP_ARGS(pool_name, pool_bits, input_bits), + + TP_STRUCT__entry( + __field( const char *, pool_name ) + __field( int, pool_bits ) + __field( int, input_bits ) + ), + + TP_fast_assign( + __entry->pool_name = pool_name; + __entry->pool_bits = pool_bits; + __entry->input_bits = input_bits; + ), + + TP_printk("%s: pool_bits %d input_pool_bits %d", + __entry->pool_name, __entry->pool_bits, + __entry->input_bits) +); + DECLARE_EVENT_CLASS(random__get_random_bytes, TP_PROTO(int nbytes, unsigned long IP),