Index: head/sys/netinet/ip_id.c =================================================================== --- head/sys/netinet/ip_id.c (revision 280787) +++ head/sys/netinet/ip_id.c (revision 280788) @@ -1,188 +1,211 @@ /*- * Copyright (c) 2008 Michael J. Silbersack. * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice unmodified, this list of conditions, and the following * disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ #include __FBSDID("$FreeBSD$"); /* * IP ID generation is a fascinating topic. * * In order to avoid ID collisions during packet reassembly, common sense * dictates that the period between reuse of IDs be as large as possible. * This leads to the classic implementation of a system-wide counter, thereby * ensuring that IDs repeat only once every 2^16 packets. * * Subsequent security researchers have pointed out that using a global * counter makes ID values predictable. This predictability allows traffic * analysis, idle scanning, and even packet injection in specific cases. * These results suggest that IP IDs should be as random as possible. * * The "searchable queues" algorithm used in this IP ID implementation was * proposed by Amit Klein. It is a compromise between the above two * viewpoints that has provable behavior that can be tuned to the user's * requirements. * * The basic concept is that we supplement a standard random number generator * with a queue of the last L IDs that we have handed out to ensure that all * IDs have a period of at least L. * * To efficiently implement this idea, we keep two data structures: a * circular array of IDs of size L and a bitstring of 65536 bits. * * To start, we ask the RNG for a new ID. A quick index into the bitstring * is used to determine if this is a recently used value. The process is * repeated until a value is returned that is not in the bitstring. * * Having found a usable ID, we remove the ID stored at the current position * in the queue from the bitstring and replace it with our new ID. Our new * ID is then added to the bitstring and the queue pointer is incremented. * * The lower limit of 512 was chosen because there doesn't seem to be much * point to having a smaller value. The upper limit of 32768 was chosen for * two reasons. First, every step above 32768 decreases the entropy. Taken * to an extreme, 65533 would offer 1 bit of entropy. Second, the number of * attempts it takes the algorithm to find an unused ID drastically * increases, killing performance. The default value of 8192 was chosen * because it provides a good tradeoff between randomness and non-repetition. * * With L=8192, the queue will use 16K of memory. The bitstring always * uses 8K of memory. No memory is allocated until the use of random ids is * enabled. */ #include #include #include #include #include #include #include #include #include #include #include +#include + +#include + #include #include -#include static MALLOC_DEFINE(M_IPID, "ipid", "randomized ip id state"); -static uint16_t *id_array; -static bitstr_t *id_bits; -static int array_ptr; -static int array_size; -static int random_id_collisions; -static int random_id_total; -static struct mtx ip_id_mtx; +static VNET_DEFINE(uint16_t *, id_array); +static VNET_DEFINE(bitstr_t *, id_bits); +static VNET_DEFINE(int, array_ptr); +static VNET_DEFINE(int, array_size); +static VNET_DEFINE(int, random_id_collisions); +static VNET_DEFINE(int, random_id_total); +static VNET_DEFINE(struct mtx, ip_id_mtx); +#define V_id_array VNET(id_array) +#define V_id_bits VNET(id_bits) +#define V_array_ptr VNET(array_ptr) +#define V_array_size VNET(array_size) +#define V_random_id_collisions VNET(random_id_collisions) +#define V_random_id_total VNET(random_id_total) +#define V_ip_id_mtx VNET(ip_id_mtx) static void ip_initid(int); static int sysctl_ip_id_change(SYSCTL_HANDLER_ARGS); -static void ip_sysinitid(void); +static void ipid_sysinit(void); +static void ipid_sysuninit(void); SYSCTL_DECL(_net_inet_ip); -SYSCTL_PROC(_net_inet_ip, OID_AUTO, random_id_period, CTLTYPE_INT|CTLFLAG_RW, - &array_size, 0, sysctl_ip_id_change, "IU", "IP ID Array size"); -SYSCTL_INT(_net_inet_ip, OID_AUTO, random_id_collisions, CTLFLAG_RD, - &random_id_collisions, 0, "Count of IP ID collisions"); -SYSCTL_INT(_net_inet_ip, OID_AUTO, random_id_total, CTLFLAG_RD, - &random_id_total, 0, "Count of IP IDs created"); +SYSCTL_PROC(_net_inet_ip, OID_AUTO, random_id_period, + CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_VNET, + &VNET_NAME(array_size), 0, sysctl_ip_id_change, "IU", "IP ID Array size"); +SYSCTL_INT(_net_inet_ip, OID_AUTO, random_id_collisions, + CTLFLAG_RD | CTLFLAG_VNET, + &VNET_NAME(random_id_collisions), 0, "Count of IP ID collisions"); +SYSCTL_INT(_net_inet_ip, OID_AUTO, random_id_total, CTLFLAG_RD | CTLFLAG_VNET, + &VNET_NAME(random_id_total), 0, "Count of IP IDs created"); static int sysctl_ip_id_change(SYSCTL_HANDLER_ARGS) { int error, new; - new = array_size; + new = V_array_size; error = sysctl_handle_int(oidp, &new, 0, req); if (error == 0 && req->newptr) { if (new >= 512 && new <= 32768) ip_initid(new); else error = EINVAL; } return (error); } static void ip_initid(int new_size) { uint16_t *new_array; bitstr_t *new_bits; new_array = malloc(new_size * sizeof(uint16_t), M_IPID, M_WAITOK | M_ZERO); new_bits = malloc(bitstr_size(65536), M_IPID, M_WAITOK | M_ZERO); - mtx_lock(&ip_id_mtx); - if (id_array != NULL) { - free(id_array, M_IPID); - free(id_bits, M_IPID); + mtx_lock(&V_ip_id_mtx); + if (V_id_array != NULL) { + free(V_id_array, M_IPID); + free(V_id_bits, M_IPID); } - id_array = new_array; - id_bits = new_bits; - array_size = new_size; - array_ptr = 0; - random_id_collisions = 0; - random_id_total = 0; - mtx_unlock(&ip_id_mtx); + V_id_array = new_array; + V_id_bits = new_bits; + V_array_size = new_size; + V_array_ptr = 0; + V_random_id_collisions = 0; + V_random_id_total = 0; + mtx_unlock(&V_ip_id_mtx); } uint16_t ip_randomid(void) { uint16_t new_id; - mtx_lock(&ip_id_mtx); + mtx_lock(&V_ip_id_mtx); /* * To avoid a conflict with the zeros that the array is initially * filled with, we never hand out an id of zero. */ new_id = 0; do { if (new_id != 0) - random_id_collisions++; + V_random_id_collisions++; arc4rand(&new_id, sizeof(new_id), 0); - } while (bit_test(id_bits, new_id) || new_id == 0); - bit_clear(id_bits, id_array[array_ptr]); - bit_set(id_bits, new_id); - id_array[array_ptr] = new_id; - array_ptr++; - if (array_ptr == array_size) - array_ptr = 0; - random_id_total++; - mtx_unlock(&ip_id_mtx); + } while (bit_test(V_id_bits, new_id) || new_id == 0); + bit_clear(V_id_bits, V_id_array[V_array_ptr]); + bit_set(V_id_bits, new_id); + V_id_array[V_array_ptr] = new_id; + V_array_ptr++; + if (V_array_ptr == V_array_size) + V_array_ptr = 0; + V_random_id_total++; + mtx_unlock(&V_ip_id_mtx); return (new_id); } static void -ip_sysinitid(void) +ipid_sysinit(void) { - mtx_init(&ip_id_mtx, "ip_id_mtx", NULL, MTX_DEF); + mtx_init(&V_ip_id_mtx, "ip_id_mtx", NULL, MTX_DEF); ip_initid(8192); } -SYSINIT(ip_id, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, ip_sysinitid, NULL); +VNET_SYSINIT(ip_id, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, ipid_sysinit, NULL); + +static void +ipid_sysuninit(void) +{ + + mtx_destroy(&V_ip_id_mtx); + free(V_id_array, M_IPID); + free(V_id_bits, M_IPID); +} +VNET_SYSUNINIT(ip_id, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY, ipid_sysuninit, NULL);