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Initialize random IP ID engine via SYSINIT() instead of doing that on

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first packet.  This allow to use M_WAITOK and cut down some error handling.

Sponsored by:	Nginx, Inc.
This commit is contained in:
glebius 2015-03-28 16:06:46 +00:00
parent edcfd40470
commit 96ef75c4d1
1 changed files with 34 additions and 55 deletions
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89
sys/netinet/ip_id.c
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@ -91,18 +91,17 @@ __FBSDID("$FreeBSD$");
static MALLOC_DEFINE(M_IPID, "ipid", "randomized ip id state");
static u_int16_t *id_array = NULL;
static bitstr_t *id_bits = NULL;
static int array_ptr = 0;
static int array_size = 8192;
static int random_id_collisions = 0;
static int random_id_total = 0;
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 void ip_initid(void);
static void ip_initid(int);
static int sysctl_ip_id_change(SYSCTL_HANDLER_ARGS);
MTX_SYSINIT(ip_id_mtx, &ip_id_mtx, "ip_id_mtx", MTX_DEF);
static void ip_sysinitid(void);
SYSCTL_DECL(_net_inet_ip);
SYSCTL_PROC(_net_inet_ip, OID_AUTO, random_id_period, CTLTYPE_INT|CTLFLAG_RW,
@ -120,73 +119,44 @@ sysctl_ip_id_change(SYSCTL_HANDLER_ARGS)
new = array_size;
error = sysctl_handle_int(oidp, &new, 0, req);
if (error == 0 && req->newptr) {
if (new >= 512 && new <= 32768) {
mtx_lock(&ip_id_mtx);
array_size = new;
ip_initid();
mtx_unlock(&ip_id_mtx);
} else
if (new >= 512 && new <= 32768)
ip_initid(new);
else
error = EINVAL;
}
return (error);
}
/*
* ip_initid() runs with a mutex held and may execute in a network context.
* As a result, it uses M_NOWAIT. Ideally, we would always do this
* allocation from the sysctl contact and have it be an invariant that if
* this random ID allocation mode is selected, the buffers are present. This
* would also avoid potential network context failures of IP ID generation.
*/
static void
ip_initid(void)
ip_initid(int new_size)
{
uint16_t *new_array;
bitstr_t *new_bits;
mtx_assert(&ip_id_mtx, MA_OWNED);
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);
}
id_array = new_array;
id_bits = new_bits;
array_size = new_size;
array_ptr = 0;
random_id_collisions = 0;
random_id_total = 0;
array_ptr = 0;
id_array = (u_int16_t *) malloc(array_size * sizeof(u_int16_t),
M_IPID, M_NOWAIT | M_ZERO);
id_bits = (bitstr_t *) malloc(bitstr_size(65536), M_IPID,
M_NOWAIT | M_ZERO);
if (id_array == NULL || id_bits == NULL) {
/* Neither or both. */
if (id_array != NULL) {
free(id_array, M_IPID);
id_array = NULL;
}
if (id_bits != NULL) {
free(id_bits, M_IPID);
id_bits = NULL;
}
}
mtx_unlock(&ip_id_mtx);
}
u_int16_t
uint16_t
ip_randomid(void)
{
u_int16_t new_id;
uint16_t new_id;
mtx_lock(&ip_id_mtx);
if (id_array == NULL)
ip_initid();
/*
* Fail gracefully; return a fixed id if memory allocation failed;
* ideally we wouldn't do allocation in this context in order to
* avoid the possibility of this failure mode.
*/
if (id_array == NULL) {
mtx_unlock(&ip_id_mtx);
return (1);
}
/*
* To avoid a conflict with the zeros that the array is initially
* filled with, we never hand out an id of zero.
@ -207,3 +177,12 @@ ip_randomid(void)
mtx_unlock(&ip_id_mtx);
return (new_id);
}
static void
ip_sysinitid(void)
{
mtx_init(&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);