Fix a bug reported by and diagnosed by Aaron Straus.

This is a regression intruduced into 2.6.26 by

    commit adc782dae6c4c0f6fb679a48a544cfbcd79ae3dc
    Author: Matt Mackall <mpm@selenic.com>
    Date:   Tue Apr 29 01:03:07 2008 -0700

        random: simplify and rename credit_entropy_store

credit_entropy_bits() does:

	spin_lock_irqsave(&r->lock, flags);
	...
	if (r->entropy_count > r->poolinfo->POOLBITS)
		r->entropy_count = r->poolinfo->POOLBITS;

so there is a time window in which this BUG_ON():

static size_t account(struct entropy_store *r, size_t nbytes, int min,
		      int reserved)
{
	unsigned long flags;

	BUG_ON(r->entropy_count > r->poolinfo->POOLBITS);

	/* Hold lock while accounting */
	spin_lock_irqsave(&r->lock, flags);

can trigger.

We could fix this by moving the assertion inside the lock, but it seems
safer and saner to revert to the old behaviour wherein
entropy_store.entropy_count at no time exceeds
entropy_store.poolinfo->POOLBITS.

Reported-by: Aaron Straus <aaron@merfinllc.com>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: <stable@kernel.org>		[2.6.26.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Use incoming network tuple as seed for NAT port randomization.
This avoids concerns of leaking net_random() bits, and also gives better
port distribution. Don't have NAT server, compile tested only.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>

[ added missing EXPORT_SYMBOL_GPL ]

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

On 32-bit architectures PAGE_ALIGN() truncates 64-bit values to the 32-bit
boundary. For example:

	u64 val = PAGE_ALIGN(size);

always returns a value < 4GB even if size is greater than 4GB.

The problem resides in PAGE_MASK definition (from include/asm-x86/page.h for
example):

#define PAGE_SHIFT      12
#define PAGE_SIZE       (_AC(1,UL) << PAGE_SHIFT)
#define PAGE_MASK       (~(PAGE_SIZE-1))
...
#define PAGE_ALIGN(addr)       (((addr)+PAGE_SIZE-1)&PAGE_MASK)

The "~" is performed on a 32-bit value, so everything in "and" with
PAGE_MASK greater than 4GB will be truncated to the 32-bit boundary.
Using the ALIGN() macro seems to be the right way, because it uses
typeof(addr) for the mask.

Also move the PAGE_ALIGN() definitions out of include/asm-*/page.h in
include/linux/mm.h.

See also lkml discussion: http://lkml.org/lkml/2008/6/11/237

[akpm@linux-foundation.org: fix drivers/media/video/uvc/uvc_queue.c]
[akpm@linux-foundation.org: fix v850]
[akpm@linux-foundation.org: fix powerpc]
[akpm@linux-foundation.org: fix arm]
[akpm@linux-foundation.org: fix mips]
[akpm@linux-foundation.org: fix drivers/media/video/pvrusb2/pvrusb2-dvb.c]
[akpm@linux-foundation.org: fix drivers/mtd/maps/uclinux.c]
[akpm@linux-foundation.org: fix powerpc]
Signed-off-by: Andrea Righi <righi.andrea@gmail.com>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Add async notification support to /dev/random.

A little test case is below.  Without this patch, you get:

$ ./async-random
Drained the pool
Found more randomness

With it, you get:

$ ./async-random
Drained the pool
SIGIO
Found more randomness

#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <errno.h>
#include <fcntl.h>

static void handler(int sig)
{
        printf("SIGIO\n");
}

int main(int argc, char **argv)
{
        int fd, n, err, flags;

        if(signal(SIGIO, handler) < 0){
                perror("setting SIGIO handler");
                exit(1);
        }

        fd = open("/dev/random", O_RDONLY);
        if(fd < 0){
                perror("open");
                exit(1);
        }

        flags = fcntl(fd, F_GETFL);
        if (flags < 0){
                perror("getting flags");
                exit(1);
        }

        flags |= O_NONBLOCK;
        if (fcntl(fd, F_SETFL, flags) < 0){
                perror("setting flags");
                exit(1);
        }

        while((err = read(fd, &n, sizeof(n))) > 0) ;

        if(err == 0){
                printf("random returned 0\n");
                exit(1);
        }
        else if(errno != EAGAIN){
                perror("read");
                exit(1);
        }

        flags |= O_ASYNC;
        if (fcntl(fd, F_SETFL, flags) < 0){
                perror("setting flags");
                exit(1);
        }

        if (fcntl(fd, F_SETOWN, getpid()) < 0) {
                perror("Setting SIGIO");
                exit(1);
        }

        printf("Drained the pool\n");
        read(fd, &n, sizeof(n));
        printf("Found more randomness\n");

        return(0);
}

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Matt Mackall <mpm@selenic.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

- emphasize bits in the name
- make zero bits lock-free
- simplify logic

Signed-off-by: Matt Mackall <mpm@selenic.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Switch add_entropy_words to a byte-oriented interface, eliminating numerous
casts and byte/word size rounding issues.  This also reduces the overall
bit/byte/word confusion in this code.

We now mix a byte at a time into the word-based pool.  This takes four times
as many iterations, but should be negligible compared to hashing overhead.
This also increases our pool churn, which adds some depth against some
theoretical failure modes.

The function name is changed to emphasize pool mixing and deemphasize entropy
(the samples mixed in may not contain any).  extract is added to the core
function to make it clear that it extracts from the pool.

Signed-off-by: Matt Mackall <mpm@selenic.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The add_ptr variable wasn't used in a sensible way, use only i instead.
i got reused later for a different purpose, use j instead.

While we're here, put tap0 first in the tap list and add a comment.

Signed-off-by: Matt Mackall <mpm@selenic.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The urandom output pool (ie the fast path) fits in one cacheline, so
this is pretty unnecessary. Further, the output path has already
fetched the entire pool to hash it before calling in here.

(This was the only user of prefetch_range in the kernel, and it passed
in words rather than bytes!)

Signed-off-by: Matt Mackall <mpm@selenic.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

- eliminate new_rotate
- move input_rotate masking
- simplify input_rotate update
- move input_rotate update to end of inner loop for readability

Signed-off-by: Matt Mackall <mpm@selenic.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Earlier changes greatly reduce the number of times we grab the lock
per output byte, so we shouldn't need this particular hack any more.

Signed-off-by: Matt Mackall <mpm@selenic.com>
Cc: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>