Commit 2e8b5d75 authored by Pauli's avatar Pauli
Browse files

Document that lhash isn't thread safe under any circumstances and 


indicate the level of locking required for various operations.

Remove the lock and atomics from the lhash code.  These we're not complete
or adequate.

Refer to #4418 and #4427 for details.

Reviewed-by: default avatarRich Salz <rsalz@openssl.org>
Reviewed-by: default avatarBen Kaduk <kaduk@mit.edu>
Reviewed-by: default avatarAndy Polyakov <appro@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4429)
parent 24b0be11

crypto/lhash/lh_stats.c

+9 −22
Original line number Diff line number Diff line 
/*

 * Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.

 * Copyright 1995-2017 The OpenSSL Project Authors. All Rights Reserved.

 *

 * Licensed under the OpenSSL license (the "License").  You may not use

 * this file except in compliance with the License.  You can obtain a copy
@@ -61,35 +61,22 @@ void OPENSSL_LH_node_usage_stats(const OPENSSL_LHASH *lh, FILE *fp) 


void OPENSSL_LH_stats_bio(const OPENSSL_LHASH *lh, BIO *out)

{

    OPENSSL_LHASH *lh_mut = (OPENSSL_LHASH *) lh;

    int ret;



    BIO_printf(out, "num_items             = %lu\n", lh->num_items);

    BIO_printf(out, "num_nodes             = %u\n",  lh->num_nodes);

    BIO_printf(out, "num_alloc_nodes       = %u\n",  lh->num_alloc_nodes);

    BIO_printf(out, "num_expands           = %lu\n", lh->num_expands);

    BIO_printf(out, "num_expand_reallocs   = %lu\n", lh->num_expand_reallocs);

    BIO_printf(out, "num_contracts         = %lu\n", lh->num_contracts);

    BIO_printf(out, "num_contract_reallocs = %lu\n",

               lh->num_contract_reallocs);

    CRYPTO_atomic_add(&lh_mut->num_hash_calls, 0, &ret,

                      lh->retrieve_stats_lock);

    BIO_printf(out, "num_hash_calls        = %d\n", ret);

    CRYPTO_atomic_add(&lh_mut->num_comp_calls, 0, &ret,

                      lh->retrieve_stats_lock);

    BIO_printf(out, "num_comp_calls        = %d\n", ret);

    BIO_printf(out, "num_contract_reallocs = %lu\n", lh->num_contract_reallocs);

    BIO_printf(out, "num_hash_calls        = %lu\n", lh->num_hash_calls);

    BIO_printf(out, "num_comp_calls        = %lu\n", lh->num_comp_calls);

    BIO_printf(out, "num_insert            = %lu\n", lh->num_insert);

    BIO_printf(out, "num_replace           = %lu\n", lh->num_replace);

    BIO_printf(out, "num_delete            = %lu\n", lh->num_delete);

    BIO_printf(out, "num_no_delete         = %lu\n", lh->num_no_delete);

    CRYPTO_atomic_add(&lh_mut->num_retrieve, 0, &ret, lh->retrieve_stats_lock);

    BIO_printf(out, "num_retrieve          = %d\n", ret);

    CRYPTO_atomic_add(&lh_mut->num_retrieve_miss, 0, &ret,

                      lh->retrieve_stats_lock);

    BIO_printf(out, "num_retrieve_miss     = %d\n", ret);

    CRYPTO_atomic_add(&lh_mut->num_hash_comps, 0, &ret,

                      lh->retrieve_stats_lock);

    BIO_printf(out, "num_hash_comps        = %d\n", ret);

    BIO_printf(out, "num_retrieve          = %lu\n", lh->num_retrieve);

    BIO_printf(out, "num_retrieve_miss     = %lu\n", lh->num_retrieve_miss);

    BIO_printf(out, "num_hash_comps        = %lu\n", lh->num_hash_comps);

}



void OPENSSL_LH_node_stats_bio(const OPENSSL_LHASH *lh, BIO *out)

crypto/lhash/lhash.c

+14 −20
Original line number Diff line number Diff line 
/*

 * Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.

 * Copyright 1995-2017 The OpenSSL Project Authors. All Rights Reserved.

 *

 * Licensed under the OpenSSL license (the "License").  You may not use

 * this file except in compliance with the License.  You can obtain a copy
@@ -32,8 +32,6 @@ OPENSSL_LHASH *OPENSSL_LH_new(OPENSSL_LH_HASHFUNC h, OPENSSL_LH_COMPFUNC c) 
        return NULL;

    if ((ret->b = OPENSSL_zalloc(sizeof(*ret->b) * MIN_NODES)) == NULL)

        goto err;

    if ((ret->retrieve_stats_lock = CRYPTO_THREAD_lock_new()) == NULL)

        goto err;

    ret->comp = ((c == NULL) ? (OPENSSL_LH_COMPFUNC)strcmp : c);

    ret->hash = ((h == NULL) ? (OPENSSL_LH_HASHFUNC)OPENSSL_LH_strhash : h);

    ret->num_nodes = MIN_NODES / 2;
@@ -41,7 +39,7 @@ OPENSSL_LHASH *OPENSSL_LH_new(OPENSSL_LH_HASHFUNC h, OPENSSL_LH_COMPFUNC c) 
    ret->pmax = MIN_NODES / 2;

    ret->up_load = UP_LOAD;

    ret->down_load = DOWN_LOAD;

    return (ret);

    return ret;



err:

    OPENSSL_free(ret->b);
@@ -65,7 +63,6 @@ void OPENSSL_LH_free(OPENSSL_LHASH *lh) 
            n = nn;

        }

    }

    CRYPTO_THREAD_lock_free(lh->retrieve_stats_lock);

    OPENSSL_free(lh->b);

    OPENSSL_free(lh);

}
@@ -85,7 +82,7 @@ void *OPENSSL_LH_insert(OPENSSL_LHASH *lh, void *data) 
    if (*rn == NULL) {

        if ((nn = OPENSSL_malloc(sizeof(*nn))) == NULL) {

            lh->error++;

            return (NULL);

            return NULL;

        }

        nn->data = data;

        nn->next = NULL;
@@ -95,12 +92,11 @@ void *OPENSSL_LH_insert(OPENSSL_LHASH *lh, void *data) 
        lh->num_insert++;

        lh->num_items++;

    } else {                    /* replace same key */



        ret = (*rn)->data;

        (*rn)->data = data;

        lh->num_replace++;

    }

    return (ret);

    return ret;

}



void *OPENSSL_LH_delete(OPENSSL_LHASH *lh, const void *data)
@@ -114,7 +110,7 @@ void *OPENSSL_LH_delete(OPENSSL_LHASH *lh, const void *data) 


    if (*rn == NULL) {

        lh->num_no_delete++;

        return (NULL);

        return NULL;

    } else {

        nn = *rn;

        *rn = nn->next;
@@ -128,7 +124,7 @@ void *OPENSSL_LH_delete(OPENSSL_LHASH *lh, const void *data) 
        (lh->down_load >= (lh->num_items * LH_LOAD_MULT / lh->num_nodes)))

        contract(lh);



    return (ret);

    return ret;

}



void *OPENSSL_LH_retrieve(OPENSSL_LHASH *lh, const void *data)
@@ -136,17 +132,16 @@ void *OPENSSL_LH_retrieve(OPENSSL_LHASH *lh, const void *data) 
    unsigned long hash;

    OPENSSL_LH_NODE **rn;

    void *ret;

    int scratch;



    lh->error = 0;

    rn = getrn(lh, data, &hash);



    if (*rn == NULL) {

        CRYPTO_atomic_add(&lh->num_retrieve_miss, 1, &scratch, lh->retrieve_stats_lock);

        lh->num_retrieve_miss++;

        return NULL;

    } else {

        ret = (*rn)->data;

        CRYPTO_atomic_add(&lh->num_retrieve, 1, &scratch, lh->retrieve_stats_lock);

        lh->num_retrieve++;

    }

    return ret;

}
@@ -274,10 +269,9 @@ static OPENSSL_LH_NODE **getrn(OPENSSL_LHASH *lh, 
    OPENSSL_LH_NODE **ret, *n1;

    unsigned long hash, nn;

    OPENSSL_LH_COMPFUNC cf;

    int scratch;



    hash = (*(lh->hash)) (data);

    CRYPTO_atomic_add(&lh->num_hash_calls, 1, &scratch, lh->retrieve_stats_lock);

    lh->num_hash_calls++;

    *rhash = hash;



    nn = hash % lh->pmax;
@@ -287,17 +281,17 @@ static OPENSSL_LH_NODE **getrn(OPENSSL_LHASH *lh, 
    cf = lh->comp;

    ret = &(lh->b[(int)nn]);

    for (n1 = *ret; n1 != NULL; n1 = n1->next) {

        CRYPTO_atomic_add(&lh->num_hash_comps, 1, &scratch, lh->retrieve_stats_lock);

        lh->num_hash_comps++;

        if (n1->hash != hash) {

            ret = &(n1->next);

            continue;

        }

        CRYPTO_atomic_add(&lh->num_comp_calls, 1, &scratch, lh->retrieve_stats_lock);

        lh->num_comp_calls++;

        if (cf(n1->data, data) == 0)

            break;

        ret = &(n1->next);

    }

    return (ret);

    return ret;

}



/*
@@ -313,7 +307,7 @@ unsigned long OPENSSL_LH_strhash(const char *c) 
    int r;



    if ((c == NULL) || (*c == '\0'))

        return (ret);

        return ret;



    n = 0x100;

    while (*c) {
@@ -325,7 +319,7 @@ unsigned long OPENSSL_LH_strhash(const char *c) 
        ret ^= v * v;

        c++;

    }

    return ((ret >> 16) ^ ret);

    return (ret >> 16) ^ ret;

}



unsigned long OPENSSL_LH_num_items(const OPENSSL_LHASH *lh)

crypto/lhash/lhash_lcl.h

+6 −13
Original line number Diff line number Diff line 
/*

 * Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.

 * Copyright 1995-2017 The OpenSSL Project Authors. All Rights Reserved.

 *

 * Licensed under the OpenSSL license (the "License").  You may not use

 * this file except in compliance with the License.  You can obtain a copy
@@ -18,13 +18,6 @@ struct lhash_st { 
    OPENSSL_LH_NODE **b;

    OPENSSL_LH_COMPFUNC comp;

    OPENSSL_LH_HASHFUNC hash;

    /*

     * some stats are updated on lookup, which callers aren't expecting to have

     * to take an exclusive lock around. This lock protects them on platforms

     * without atomics, and their types are int rather than unsigned long below

     * so they can be adjusted with CRYPTO_atomic_add.

     */

    CRYPTO_RWLOCK *retrieve_stats_lock;

    unsigned int num_nodes;

    unsigned int num_alloc_nodes;

    unsigned int p;
@@ -36,14 +29,14 @@ struct lhash_st { 
    unsigned long num_expand_reallocs;

    unsigned long num_contracts;

    unsigned long num_contract_reallocs;

    int num_hash_calls;

    int num_comp_calls;

    unsigned long num_hash_calls;

    unsigned long num_comp_calls;

    unsigned long num_insert;

    unsigned long num_replace;

    unsigned long num_delete;

    unsigned long num_no_delete;

    int num_retrieve;

    int num_retrieve_miss;

    int num_hash_comps;

    unsigned long num_retrieve;

    unsigned long num_retrieve_miss;

    unsigned long num_hash_comps;

    int error;

};

doc/man3/OPENSSL_LH_COMPFUNC.pod

+8 −1
Original line number Diff line number Diff line
@@ -184,6 +184,13 @@ audit/verify and also opens the window of opportunity for stack 
corruption and other hard-to-find bugs.  It also, apparently, violates

ANSI-C.



The LHASH code is not thread safe. All updating operations must be

performed under a write lock. All retrieve operations should be performed

under a read lock, I<unless> accurate usage statistics are desired.

In which case, a write lock should be used for retrieve operations

as well.  For output of the usage statistics, using the functions from

L<OPENSSL_LH_stats(3)>, a read lock suffices.



The LHASH code regards table entries as constant data.  As such, it

internally represents lh_insert()'d items with a "const void *"

pointer type.  This is why callbacks such as those used by lh_doall()
@@ -229,7 +236,7 @@ type checking. 


=head1 COPYRIGHT



Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.

Copyright 2000-2017 The OpenSSL Project Authors. All Rights Reserved.



Licensed under the OpenSSL license (the "License").  You may not use

this file except in compliance with the License.  You can obtain a copy

doc/man3/OPENSSL_LH_stats.pod

+8 −2
Original line number Diff line number Diff line
@@ -46,13 +46,19 @@ are the same as the above, except that the output goes to a B<BIO>. 


These functions do not return values.



=head1 NOTE



These calls should be made under a read lock. Refer to

L<OPENSSL_LH_COMPFUNC(3)/NOTE> for more details about the locks required

when using the LHASH data structure.



=head1 SEE ALSO



L<bio(7)>, L<LHASH(3)>

L<bio(7)>, L<OPENSSL_LH_COMPFUNC(3)>



=head1 COPYRIGHT



Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.

Copyright 2000-2017 The OpenSSL Project Authors. All Rights Reserved.



Licensed under the OpenSSL license (the "License").  You may not use

this file except in compliance with the License.  You can obtain a copy