/dev/random cleanup: 04-pool-cleanup

/dev/random cleanup: 04-pool-cleanup

Post by Oliver Xymoro » Sun, 29 Sep 2002 08:00:07



- more meaningful names for pools (predicting next patch)
- cleanup of pool structure
  - store name
  - point to poolinfo table rather than copying entry
  - alloc pool together with structure
- refactor pool creation and initialization
- kill pointless (double!) pool zeroing

diff -urN -x '.patch*' -x '*.orig' orig/drivers/char/random.c work/drivers/char/random.c
--- orig/drivers/char/random.c  2002-09-28 00:16:14.000000000 -0500
+++ work/drivers/char/random.c  2002-09-28 00:16:15.000000000 -0500
@@ -257,12 +257,6 @@
 #include <asm/irq.h>
 #include <asm/io.h>

-/*
- * Configuration information
- */
-#define DEFAULT_POOL_SIZE 512
-#define SECONDARY_POOL_SIZE 128
-#define BATCH_ENTROPY_SIZE 256
 #define USE_SHA

 /*
@@ -287,8 +281,8 @@
  * get the twisting happening as fast as possible.
  */
 static struct poolinfo {
-       int     poolwords;
-       int     tap1, tap2, tap3, tap4, tap5;
+       int poolwords;
+       int tap1, tap2, tap3, tap4, tap5;
 } poolinfo_table[] = {
        /* x^2048 + x^1638 + x^1231 + x^819 + x^411 + x + 1  -- 115 */
        { 2048, 1638,   1231,   819,    411,    1 },
@@ -387,8 +381,7 @@
 /*
  * Static global variables
  */
-static struct entropy_store *random_state; /* The default global store */
-static struct entropy_store *sec_random_state; /* secondary store */
+static struct entropy_store *input_pool, *blocking_pool;
 static DECLARE_WAIT_QUEUE_HEAD(random_read_wait);
 static DECLARE_WAIT_QUEUE_HEAD(random_write_wait);

@@ -396,7 +389,7 @@
  * Forward procedure declarations
  */
 #ifdef CONFIG_SYSCTL
-static void sysctl_init_random(struct entropy_store *random_state);
+static void sysctl_init_random(struct entropy_store *input_pool);
 #endif

 /*****************************************************************
@@ -441,24 +434,19 @@
  **********************************************************************/

 struct entropy_store {
-       unsigned        add_ptr;
-       int             entropy_count;
-       int             input_rotate;
-       struct poolinfo poolinfo;
-       __u32           *pool;
+       const char *name;
+       unsigned add_ptr;
+       int entropy_count;
+       int input_rotate;
+       struct poolinfo *poolinfo;
+       __u32 pool[0];
 };

-/*
- * Initialize the entropy store.  The input argument is the size of
- * the random pool.
- *
- * Returns an negative error if there is a problem.
- */
-static int create_entropy_store(int size, struct entropy_store **ret_bucket)
+struct entropy_store *create_entropy_store(int size, const char *name)
 {
-       struct  entropy_store   *r;
-       struct  poolinfo        *p;
-       int     poolwords;
+       struct entropy_store    *r;
+       struct poolinfo *p;
+       int poolwords;

        poolwords = (size + 3) / 4; /* Convert bytes->words */
        /* The pool size must be a multiple of 16 32-bit words */
@@ -469,43 +457,34 @@
                        break;
        }
        if (p->poolwords == 0)
-               return -EINVAL;
+               return 0;

-       r = kmalloc(sizeof(struct entropy_store), GFP_KERNEL);
+       r = kmalloc(sizeof(struct entropy_store)+POOLBYTES, GFP_KERNEL);
        if (!r)
-               return -ENOMEM;
+               return 0;

-       memset (r, 0, sizeof(struct entropy_store));
-       r->poolinfo = *p;
+       memset(r, 0, sizeof(struct entropy_store));
+       r->name = name;
+       r->poolinfo = p;

-       r->pool = kmalloc(POOLBYTES, GFP_KERNEL);
-       if (!r->pool) {
-               kfree(r);
-               return -ENOMEM;
-       }
-       memset(r->pool, 0, POOLBYTES);
-       *ret_bucket = r;
-       return 0;
+       return r;
 }

-/* Clear the entropy pool and associated counters. */
+/* Clear the entropy pool counters. */
 static void clear_entropy_store(struct entropy_store *r)
 {
        r->add_ptr = 0;
        r->entropy_count = 0;
        r->input_rotate = 0;
-       memset(r->pool, 0, r->poolinfo.POOLBYTES);
 }

 static void free_entropy_store(struct entropy_store *r)
 {
-       if (r->pool)
-               kfree(r->pool);
        kfree(r);
 }

 /*
- * This function adds a word into the entropy "pool".  It does not
+ * This function adds words into the entropy "pool".  It does not
  * update the entropy estimate.  The caller should call
  * credit_entropy_store if this is appropriate.
  *
@@ -522,7 +501,7 @@
                0xedb88320, 0xd6d6a3e8, 0x9b64c2b0, 0xa00ae278 };
        unsigned i;
        int new_rotate;
-       int wordmask = r->poolinfo.poolwords - 1;
+       int wordmask = r->poolinfo->poolwords - 1;
        __u32 w;

        while (nwords--) {
@@ -540,11 +519,11 @@
                r->input_rotate = new_rotate & 31;

                /* XOR in the various taps */
-               w ^= r->pool[(i + r->poolinfo.tap1) & wordmask];
-               w ^= r->pool[(i + r->poolinfo.tap2) & wordmask];
-               w ^= r->pool[(i + r->poolinfo.tap3) & wordmask];
-               w ^= r->pool[(i + r->poolinfo.tap4) & wordmask];
-               w ^= r->pool[(i + r->poolinfo.tap5) & wordmask];
+               w ^= r->pool[(i + r->poolinfo->tap1) & wordmask];
+               w ^= r->pool[(i + r->poolinfo->tap2) & wordmask];
+               w ^= r->pool[(i + r->poolinfo->tap3) & wordmask];
+               w ^= r->pool[(i + r->poolinfo->tap4) & wordmask];
+               w ^= r->pool[(i + r->poolinfo->tap5) & wordmask];
                w ^= r->pool[i];
                r->pool[i] = (w >> 3) ^ twist_table[w & 7];
        }
@@ -559,15 +538,13 @@
                DEBUG_ENT("negative entropy/overflow (%d+%d)\n",
                          r->entropy_count, nbits);
                r->entropy_count = 0;
-       } else if (r->entropy_count + nbits > r->poolinfo.POOLBITS) {
-               r->entropy_count = r->poolinfo.POOLBITS;
+       } else if (r->entropy_count + nbits > r->poolinfo->POOLBITS) {
+               r->entropy_count = r->poolinfo->POOLBITS;
        } else {
                r->entropy_count += nbits;
                if (nbits)
                        DEBUG_ENT("%s added %d bits, now %d\n",
-                                 r == sec_random_state ? "secondary" :
-                                 r == random_state ? "primary" : "unknown",
-                                 nbits, r->entropy_count);
+                                 r->name, nbits, r->entropy_count);
        }
 }

@@ -582,10 +559,10 @@
 static __u32 *batch_entropy_pool=0;
 static int batch_max, batch_pos, batch_credit, batch_samples;
 static struct tq_struct        batch_tqueue;
-static void batch_entropy_process(void *private_);
+static void batch_entropy_process(void *v);

 /* note: the size must be a power of 2 */
-static int __init batch_entropy_init(int size, struct entropy_store *r)
+static int __init batch_entropy_init(int size)
 {
        batch_entropy_pool = kmalloc(size*sizeof(__u32), GFP_KERNEL);
        if (!batch_entropy_pool)
@@ -594,7 +571,6 @@
        batch_pos = batch_credit = batch_samples = 0;
        batch_max = size;
        batch_tqueue.routine = batch_entropy_process;
-       batch_tqueue.data = r;
        return 0;
 }

@@ -624,27 +600,24 @@

 /*
  * Flush out the accumulated entropy operations, adding entropy to the
- * passed store (normally random_state). Alternate between randomizing
+ * passed store (normally input_pool). Alternate between randomizing
  * the data of the primary and secondary stores.
  */
 static void batch_entropy_process(void *private_)
 {
-       struct entropy_store *r = (struct entropy_store *) private_;
+       struct entropy_store *r = input_pool;
        int samples, credit;

        if (!batch_max)
                return;

-       /* switch pools if current full */
-       if (r->entropy_count >= r->poolinfo.POOLBITS) {
-               r = (r == sec_random_state) ?
-                       random_state : sec_random_state;
-       }
-
        credit=batch_credit;
        samples=batch_samples;
        batch_pos = batch_credit = batch_samples = 0;

+       /* switch pools if current full */
+       if (r->entropy_count >= r->poolinfo->POOLBITS) r = blocking_pool;
+
        /* Don't allow more credit BITS than pool WORDS */
        if(credit > batch_max) credit=batch_max;
        /* Check for pool wrap-around */
@@ -653,7 +626,7 @@
        add_entropy_words(r, batch_entropy_pool, samples);
        credit_entropy_store(r, credit);

-       if (r->entropy_count >= random_read_wakeup_thresh)
+       if (input_pool->entropy_count >= random_read_wakeup_thresh)
                wake_up_interruptible(&random_read_wait);
 }

@@ -1200,21 +1173,18 @@
  * in the secondary pool.  The other is after we have extracted 1024 bytes,
  * at which point we do a "catastrophic reseeding".
  */
-static inline void xfer_secondary_pool(struct entropy_store *r,
-                                      size_t nbytes)
+static void xfer_entropy(struct entropy_store *r, size_t nbytes)
 {
        __u32 tmp[TMP_BUF_SIZE];

        if (r->entropy_count < nbytes * 8 &&
-           r->entropy_count < r->poolinfo.POOLBITS) {
+           r->entropy_count < r->poolinfo->POOLBITS) {
                int bytes = min_t(int, nbytes, sizeof(tmp));

                DEBUG_ENT("xfer %d to %s (have %d, need %d)\n",
-                         bytes * 8,
-                         r == sec_random_state ? "secondary" : "unknown",
-                         r->entropy_count, nbytes * 8);
+                         bytes * 8, r->name, r->entropy_count, nbytes * 8);

-               extract_entropy(random_state, tmp, bytes, 0);
+               extract_entropy(input_pool, tmp, bytes, 0);
                add_entropy_words(r, tmp, bytes);
                credit_entropy_store(r, bytes*8);
        }
@@ -1241,16 +1211,14 @@
        __u32 x;

        /* Redundant, but just in case... */
-       if (r->entropy_count > r->poolinfo.POOLBITS)
-               r->entropy_count = r->poolinfo.POOLBITS;
+       if (r->entropy_count > r->poolinfo->POOLBITS)
+               r->entropy_count = r->poolinfo->POOLBITS;

        if (flags & EXTRACT_ENTROPY_SECONDARY)
                xfer_secondary_pool(r, nbytes);

        DEBUG_ENT("%s has %d bits, want %d bits\n",
-                 r == sec_random_state ? "secondary" :
-                 r == random_state ? "primary" : "unknown",
-                 r->entropy_count, nbytes * 8);
+                 r->name, r->entropy_count, nbytes * 8);

        if (r->entropy_count / 8 >= nbytes)
                r->entropy_count -= nbytes*8;
@@ -1290,7 +1258,7 @@
                 * attempts to find previous ouputs), unless the hash
                 * function can be inverted.
                 */
-               for (i = 0, x = 0; i < r->poolinfo.poolwords; i += 16, x+=2) {
+               for (i = 0, x = 0; i < r->poolinfo->poolwords; i += 16, x+=2) {
                        HASH_TRANSFORM(tmp, r->pool+i);
                        add_entropy_words(r, &tmp[x%HASH_BUFFER_SIZE], 1);
                }
@@ -1335,11 +1303,11 @@
  */
 void get_random_bytes(void *buf, int nbytes)
 {
-       if (sec_random_state)  
-               extract_entropy(sec_random_state, (char *) buf, nbytes,
+       if (blocking_pool)  
+               extract_entropy(blocking_pool, (char *) buf, nbytes,
                                EXTRACT_ENTROPY_SECONDARY);
-       else if (random_state)
-               extract_entropy(random_state, (char *) buf, nbytes, 0);
+       else if (input_pool)
+               extract_entropy(input_pool, (char *) buf, nbytes, 0);
        else
                printk(KERN_NOTICE "get_random_bytes called before "
                                   "random driver initialization\n");
@@ -1382,17 +1350,15 @@

 void __init rand_initialize(void)
 {
-       if (create_entropy_store(DEFAULT_POOL_SIZE, &random_state))
-               return;         /* Error, return */
-       if (batch_entropy_init(BATCH_ENTROPY_SIZE, random_state))
-               return;         /* Error, return */
-       if (create_entropy_store(SECONDARY_POOL_SIZE, &sec_random_state))
-               return;         /* Error, return */
-       clear_entropy_store(random_state);
-       clear_entropy_store(sec_random_state);
-       init_std_data(random_state);
+       input_pool = create_entropy_store(512, "input");
+       blocking_pool = create_entropy_store(128, "blocking");
+
+       if(!(input_pool && blocking_pool)) return;
+       if(batch_entropy_init(256)) return;
+
+       init_std_data(input_pool);
 #ifdef CONFIG_SYSCTL
-       sysctl_init_random(random_state);
+       sysctl_init_random(input_pool);
 #endif
        generic_kbd = create_entropy_source(1);
        generic_mouse = create_entropy_source(1);
@@ -1422,8 +1388,8 @@
                n = nbytes;
                if (n > SEC_XFER_SIZE)
                        n = SEC_XFER_SIZE;
-               if (n > random_state->entropy_count / 8)
-                       n = random_state->entropy_count / 8;
+               if (n > blocking_pool->entropy_count / 8)
+                       n = blocking_pool->entropy_count / 8;
                if (n == 0) {
                        if (file->f_flags & O_NONBLOCK) {
                                retval = -EAGAIN;
@@ -1438,12 +1404,13 @@
                }

                DEBUG_ENT("extracting %d bits, p: %d s: %d\n",
-                         n*8, random_state->entropy_count,
-                         sec_random_state->entropy_count);
+                         n*8, input_pool->entropy_count,
+                         blocking_pool->entropy_count);

-               n = extract_entropy(sec_random_state, buf, n,
+               n = extract_entropy(blocking_pool, buf, n,
                                    EXTRACT_ENTROPY_USER |
                                    EXTRACT_ENTROPY_SECONDARY);
+
                if (n < 0) {
                        retval = n;
                        break;
@@ -1471,7 +1438,7 @@
 urandom_read(struct file * file, char * buf,
                      size_t nbytes, loff_t *ppos)
 {
-       return extract_entropy(sec_random_state, buf, nbytes,
+       return extract_entropy(blocking_pool, buf, nbytes,
                               EXTRACT_ENTROPY_USER |
                               EXTRACT_ENTROPY_SECONDARY);
 }
@@ -1484,9 +1451,9 @@
        poll_wait(file, &random_read_wait, wait);
        poll_wait(file, &random_write_wait, wait);
        mask = 0;
-       if (random_state->entropy_count >= random_read_wakeup_thresh)
+       if (input_pool->entropy_count >= random_read_wakeup_thresh)
                mask |= POLLIN | POLLRDNORM;
-       if (random_state->entropy_count < random_write_wakeup_thresh)
+       if (input_pool->entropy_count < random_write_wakeup_thresh)
                mask |= POLLOUT | POLLWRNORM;
        return mask;
 }
@@ -1512,7 +1479,7 @@
                c -= bytes;
                p += bytes;

-               add_entropy_words(random_state, buf, (bytes + 3) / 4);
+               add_entropy_words(input_pool, buf, (bytes + 3) / 4);
        }
        if (p == buffer) {
                return (ssize_t)ret;
@@ -1532,7 +1499,7 @@

        switch (cmd) {
        case RNDGETENTCNT:
-               ent_count = random_state->entropy_count;
+               ent_count = input_pool->entropy_count;
                if (put_user(ent_count, (int *) arg))
                        return -EFAULT;
                return 0;
@@ -1541,28 +1508,28 @@
                        return -EPERM;
                if (get_user(ent_count, (int *) arg))
                        return -EFAULT;
-               credit_entropy_store(random_state, ent_count);
+               credit_entropy_store(input_pool, ent_count);
                /*
                 * Wake up waiting processes if we have enough
                 * entropy.
                 */
-               if (random_state->entropy_count >= random_read_wakeup_thresh)
+               if (input_pool->entropy_count >= random_read_wakeup_thresh)
                        wake_up_interruptible(&random_read_wait);
                return 0;
        case RNDGETPOOL:
                if (!capable(CAP_SYS_ADMIN))
                        return -EPERM;
                p = (int *) arg;
-               ent_count = random_state->entropy_count;
+               ent_count = input_pool->entropy_count;
                if (put_user(ent_count, p++) ||
                    get_user(size, p) ||
-                   put_user(random_state->poolinfo.poolwords, p++))
+                   put_user(input_pool->poolinfo->poolwords, p++))
                        return -EFAULT;
                if (size < 0)
                        return -EINVAL;
-               if (size > random_state->poolinfo.poolwords)
-                       size = random_state->poolinfo.poolwords;
-               if (copy_to_user(p, random_state->pool, size * 4))
+               if (size > input_pool->poolinfo->poolwords)
+                       size = input_pool->poolinfo->poolwords;
+               if (copy_to_user(p, input_pool->pool, size * 4))
                        return -EFAULT;
                return 0;
        case RNDADDENTROPY:
@@ -1579,25 +1546,25 @@
                                      size, &file->f_pos);
                if (retval < 0)
                        return retval;
-               credit_entropy_store(random_state, ent_count);
+               credit_entropy_store(input_pool, ent_count);
                /*
                 * Wake up waiting processes if we have enough
                 * entropy.
                 */
-               if (random_state->entropy_count >= random_read_wakeup_thresh)
+               if (input_pool->entropy_count >= random_read_wakeup_thresh)
                        wake_up_interruptible(&random_read_wait);
                return 0;
        case RNDZAPENTCNT:
                if (!capable(CAP_SYS_ADMIN))
                        return -EPERM;
-               random_state->entropy_count = 0;
+               input_pool->entropy_count = 0;
                return 0;
        case RNDCLEARPOOL:
                /* Clear the entropy pool and associated counters. */
                if (!capable(CAP_SYS_ADMIN))
                        return -EPERM;
-               clear_entropy_store(random_state);
-               init_std_data(random_state);
+               clear_entropy_store(input_pool);
+               init_std_data(input_pool);
                return 0;
        default:
                return -EINVAL;
@@ -1653,7 +1620,7 @@

 /*
  * This function handles a request from the user to change the pool size
- * of the primary entropy store.
+ * of the input entropy store.
  */
 static int change_poolsize(int poolsize)
 {
@@ -1663,13 +1630,13 @@
        if ((ret = create_entropy_store(poolsize, &new_store)))
                return ret;

-       add_entropy_words(new_store, random_state->pool,
-                         random_state->poolinfo.poolwords);
-       credit_entropy_store(new_store, random_state->entropy_count);
+       add_entropy_words(new_store, input_pool->pool,
+                         input_pool->poolinfo->poolwords);
+       credit_entropy_store(new_store, input_pool->entropy_count);

        sysctl_init_random(new_store);
-       old_store = random_state;
-       random_state = batch_tqueue.data = new_store;
+       old_store = input_pool;
+       input_pool = new_store;
        free_entropy_store(old_store);
        return 0;
 }
@@ -1679,11 +1646,11 @@
 {
        int     ret;

-       sysctl_poolsize = random_state->poolinfo.POOLBYTES;
+       sysctl_poolsize = input_pool->poolinfo->POOLBYTES;

        ret = proc_dointvec(table, write, filp, buffer, lenp);
        if (ret || !write ||
-           (sysctl_poolsize == random_state->poolinfo.POOLBYTES))
+           (sysctl_poolsize == input_pool->poolinfo->POOLBYTES))
                return ret;

        return change_poolsize(sysctl_poolsize);
@@ -1695,7 +1662,7 @@
 {
        int     len;

-       sysctl_poolsize = random_state->poolinfo.POOLBYTES;
+       sysctl_poolsize = input_pool->poolinfo->POOLBYTES;

        /*
         * We only handle the write case, since the read case gets
@@ -1710,7 +1677,7 @@
                        return -EFAULT;
        }

-       if (sysctl_poolsize != random_state->poolinfo.POOLBYTES)
+       if (sysctl_poolsize != input_pool->poolinfo->POOLBYTES)
                return change_poolsize(sysctl_poolsize);

        return 0;
@@ -1809,12 +1776,12 @@
        {0}
 };

-static void sysctl_init_random(struct entropy_store *random_state)
+static void sysctl_init_random(struct entropy_store *pool)
 {
        min_read_thresh = 8;
        min_write_thresh = 0;
-       max_read_thresh = max_write_thresh = random_state->poolinfo.POOLBITS;
-       random_table[1].data = &random_state->entropy_count;
+       max_read_thresh = max_write_thresh = pool->poolinfo->POOLBITS;
+       random_table[1].data = &pool->entropy_count;
 }
 #endif         /* CONFIG_SYSCTL */

-
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