Commit 5df04ac9 authored by Stefan Fritsch's avatar Stefan Fritsch
Browse files

Call apr_random_after_fork() manually in the child processes because the MPMs 

use plain fork() and not apr_proc_fork().
Also add some workaround for APR not changing the RNG state in the parent.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1198868 13f79535-47bb-0310-9956-ffa450edef68
parent cea182f3

include/mod_core.h

+3 −0
Changes for include/mod_core.h: 3 added lines, 0 removed lines.
Original line number Diff line number Diff line
@@ -90,6 +90,9 @@ AP_DECLARE(int) ap_send_http_options(request_rec *r); 
/* Used for multipart/byteranges boundary string */

extern AP_DECLARE_DATA const char *ap_multipart_boundary;



/* Update RNG state in parent after fork */

AP_CORE_DECLARE(void) ap_random_parent_after_fork(void);



#ifdef __cplusplus

}

#endif

server/core.c

+29 −7
Changes for server/core.c: 29 added lines, 7 removed lines.
Original line number Diff line number Diff line
@@ -4597,16 +4597,40 @@ AP_DECLARE(int) ap_state_query(int query) 
static apr_random_t *rng = NULL;

#if APR_HAS_THREADS

static apr_thread_mutex_t *rng_mutex = NULL;

#endif



static void create_rng_mutex(apr_pool_t *pchild, server_rec *s)

static void core_child_init(apr_pool_t *pchild, server_rec *s)

{

    apr_proc_t proc;

#if APR_HAS_THREADS

    int threaded_mpm;

    if (ap_mpm_query(AP_MPMQ_IS_THREADED, &threaded_mpm) != APR_SUCCESS)

        return;

    if (threaded_mpm)

    if (ap_mpm_query(AP_MPMQ_IS_THREADED, &threaded_mpm) == APR_SUCCESS

        && threaded_mpm)

    {

        apr_thread_mutex_create(&rng_mutex, APR_THREAD_MUTEX_DEFAULT, pchild);

    }

#endif

    /* The MPMs use plain fork() and not apr_proc_fork(), so we have to call

     * apr_random_after_fork() manually in the child

     */

    proc.pid = getpid();

    apr_random_after_fork(&proc);

}



AP_CORE_DECLARE(void) ap_random_parent_after_fork(void)

{

    /*

     * To ensure that the RNG state in the parent changes after the fork, we

     * pull some data from the RNG and discard it. This ensures that the RNG

     * states in the children ar different even after the pid wraps around.

     * As we only use apr_random for insecure random bytes, pulling 2 bytes

     * should be enough.

     * XXX: APR should probably have some dedicated API to do this, but it

     * XXX: currently doesn't.

     */

    apr_uint16_t data;

    apr_random_insecure_bytes(rng, &data, sizeof(data));

}



static void rng_init(apr_pool_t *p)

{
@@ -4735,9 +4759,7 @@ static void register_hooks(apr_pool_t *p) 
    ap_hook_translate_name(ap_core_translate,NULL,NULL,APR_HOOK_REALLY_LAST);

    ap_hook_map_to_storage(core_map_to_storage,NULL,NULL,APR_HOOK_REALLY_LAST);

    ap_hook_open_logs(ap_open_logs,NULL,NULL,APR_HOOK_REALLY_FIRST);

#if APR_HAS_THREADS

    ap_hook_child_init(create_rng_mutex,NULL,NULL,APR_HOOK_REALLY_FIRST);

#endif

    ap_hook_child_init(core_child_init,NULL,NULL,APR_HOOK_REALLY_FIRST);

    ap_hook_child_init(ap_logs_child_init,NULL,NULL,APR_HOOK_MIDDLE);

    ap_hook_handler(default_handler,NULL,NULL,APR_HOOK_REALLY_LAST);

    /* FIXME: I suspect we can eliminate the need for these do_nothings - Ben */

server/mpm_common.c

+2 −0
Changes for server/mpm_common.c: 2 added lines, 0 removed lines.
Original line number Diff line number Diff line
@@ -41,6 +41,7 @@ 
#include "http_log.h"

#include "http_main.h"

#include "mpm_common.h"

#include "mod_core.h"

#include "ap_mpm.h"

#include "ap_listen.h"

#include "util_mutex.h"
@@ -453,6 +454,7 @@ void ap_core_child_status(server_rec *s, pid_t pid, 
            APR_RING_ELEM_INIT(cur, link);

            APR_RING_INSERT_HEAD(geninfo, cur, mpm_gen_info_t, link);

        }

        ap_random_parent_after_fork();

        ++cur->active;

        break;

    case MPM_CHILD_EXITED: