freebsd-dev/sys/kern/kern_uuid.c
Robert Watson 77dfcdc445 Rework global locks for interface list and index management, correcting
several critical bugs, including race conditions and lock order issues:

Replace the single rwlock, ifnet_lock, with two locks, an rwlock and an
sxlock.  Either can be held to stablize the lists and indexes, but both
are required to write.  This allows the list to be held stable in both
network interrupt contexts and sleepable user threads across sleeping
memory allocations or device driver interactions.  As before, writes to
the interface list must occur from sleepable contexts.

Reviewed by:	bz, julian
MFC after:	3 days
2009-08-23 20:40:19 +00:00

370 lines
9.9 KiB
C

/*-
* Copyright (c) 2002 Marcel Moolenaar
* 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, 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 <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/endian.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/sbuf.h>
#include <sys/socket.h>
#include <sys/sysproto.h>
#include <sys/systm.h>
#include <sys/jail.h>
#include <sys/uuid.h>
#include <net/if.h>
#include <net/if_dl.h>
#include <net/if_types.h>
#include <net/vnet.h>
/*
* See also:
* http://www.opengroup.org/dce/info/draft-leach-uuids-guids-01.txt
* http://www.opengroup.org/onlinepubs/009629399/apdxa.htm
*
* Note that the generator state is itself an UUID, but the time and clock
* sequence fields are written in the native byte order.
*/
CTASSERT(sizeof(struct uuid) == 16);
/* We use an alternative, more convenient representation in the generator. */
struct uuid_private {
union {
uint64_t ll; /* internal. */
struct {
uint32_t low;
uint16_t mid;
uint16_t hi;
} x;
} time;
uint16_t seq; /* Big-endian. */
uint16_t node[UUID_NODE_LEN>>1];
};
CTASSERT(sizeof(struct uuid_private) == 16);
static struct uuid_private uuid_last;
static struct mtx uuid_mutex;
MTX_SYSINIT(uuid_lock, &uuid_mutex, "UUID generator mutex lock", MTX_DEF);
/*
* Return the first MAC address we encounter or, if none was found,
* construct a sufficiently random multicast address. We don't try
* to return the same MAC address as previously returned. We always
* generate a new multicast address if no MAC address exists in the
* system.
* It would be nice to know if 'ifnet' or any of its sub-structures
* has been changed in any way. If not, we could simply skip the
* scan and safely return the MAC address we returned before.
*/
static void
uuid_node(uint16_t *node)
{
struct ifnet *ifp;
struct ifaddr *ifa;
struct sockaddr_dl *sdl;
int i;
CURVNET_SET(TD_TO_VNET(curthread));
IFNET_RLOCK_NOSLEEP();
TAILQ_FOREACH(ifp, &V_ifnet, if_link) {
/* Walk the address list */
IF_ADDR_LOCK(ifp);
TAILQ_FOREACH(ifa, &ifp->if_addrhead, ifa_link) {
sdl = (struct sockaddr_dl*)ifa->ifa_addr;
if (sdl != NULL && sdl->sdl_family == AF_LINK &&
sdl->sdl_type == IFT_ETHER) {
/* Got a MAC address. */
bcopy(LLADDR(sdl), node, UUID_NODE_LEN);
IF_ADDR_UNLOCK(ifp);
IFNET_RUNLOCK_NOSLEEP();
CURVNET_RESTORE();
return;
}
}
IF_ADDR_UNLOCK(ifp);
}
IFNET_RUNLOCK_NOSLEEP();
for (i = 0; i < (UUID_NODE_LEN>>1); i++)
node[i] = (uint16_t)arc4random();
*((uint8_t*)node) |= 0x01;
CURVNET_RESTORE();
}
/*
* Get the current time as a 60 bit count of 100-nanosecond intervals
* since 00:00:00.00, October 15,1582. We apply a magic offset to convert
* the Unix time since 00:00:00.00, January 1, 1970 to the date of the
* Gregorian reform to the Christian calendar.
*/
static uint64_t
uuid_time(void)
{
struct bintime bt;
uint64_t time = 0x01B21DD213814000LL;
bintime(&bt);
time += (uint64_t)bt.sec * 10000000LL;
time += (10000000LL * (uint32_t)(bt.frac >> 32)) >> 32;
return (time & ((1LL << 60) - 1LL));
}
struct uuid *
kern_uuidgen(struct uuid *store, size_t count)
{
struct uuid_private uuid;
uint64_t time;
size_t n;
mtx_lock(&uuid_mutex);
uuid_node(uuid.node);
time = uuid_time();
if (uuid_last.time.ll == 0LL || uuid_last.node[0] != uuid.node[0] ||
uuid_last.node[1] != uuid.node[1] ||
uuid_last.node[2] != uuid.node[2])
uuid.seq = (uint16_t)arc4random() & 0x3fff;
else if (uuid_last.time.ll >= time)
uuid.seq = (uuid_last.seq + 1) & 0x3fff;
else
uuid.seq = uuid_last.seq;
uuid_last = uuid;
uuid_last.time.ll = (time + count - 1) & ((1LL << 60) - 1LL);
mtx_unlock(&uuid_mutex);
/* Set sequence and variant and deal with byte order. */
uuid.seq = htobe16(uuid.seq | 0x8000);
for (n = 0; n < count; n++) {
/* Set time and version (=1). */
uuid.time.x.low = (uint32_t)time;
uuid.time.x.mid = (uint16_t)(time >> 32);
uuid.time.x.hi = ((uint16_t)(time >> 48) & 0xfff) | (1 << 12);
store[n] = *(struct uuid *)&uuid;
time++;
}
return (store);
}
#ifndef _SYS_SYSPROTO_H_
struct uuidgen_args {
struct uuid *store;
int count;
};
#endif
int
uuidgen(struct thread *td, struct uuidgen_args *uap)
{
struct uuid *store;
size_t count;
int error;
/*
* Limit the number of UUIDs that can be created at the same time
* to some arbitrary number. This isn't really necessary, but I
* like to have some sort of upper-bound that's less than 2G :-)
* XXX probably needs to be tunable.
*/
if (uap->count < 1 || uap->count > 2048)
return (EINVAL);
count = uap->count;
store = malloc(count * sizeof(struct uuid), M_TEMP, M_WAITOK);
kern_uuidgen(store, count);
error = copyout(store, uap->store, count * sizeof(struct uuid));
free(store, M_TEMP);
return (error);
}
int
snprintf_uuid(char *buf, size_t sz, struct uuid *uuid)
{
struct uuid_private *id;
int cnt;
id = (struct uuid_private *)uuid;
cnt = snprintf(buf, sz, "%08x-%04x-%04x-%04x-%04x%04x%04x",
id->time.x.low, id->time.x.mid, id->time.x.hi, be16toh(id->seq),
be16toh(id->node[0]), be16toh(id->node[1]), be16toh(id->node[2]));
return (cnt);
}
int
printf_uuid(struct uuid *uuid)
{
char buf[38];
snprintf_uuid(buf, sizeof(buf), uuid);
return (printf("%s", buf));
}
int
sbuf_printf_uuid(struct sbuf *sb, struct uuid *uuid)
{
char buf[38];
snprintf_uuid(buf, sizeof(buf), uuid);
return (sbuf_printf(sb, "%s", buf));
}
/*
* Encode/Decode UUID into byte-stream.
* http://www.opengroup.org/dce/info/draft-leach-uuids-guids-01.txt
*
* 0 1 2 3
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | time_low |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | time_mid | time_hi_and_version |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* |clk_seq_hi_res | clk_seq_low | node (0-1) |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | node (2-5) |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*/
void
le_uuid_enc(void *buf, struct uuid const *uuid)
{
u_char *p;
int i;
p = buf;
le32enc(p, uuid->time_low);
le16enc(p + 4, uuid->time_mid);
le16enc(p + 6, uuid->time_hi_and_version);
p[8] = uuid->clock_seq_hi_and_reserved;
p[9] = uuid->clock_seq_low;
for (i = 0; i < _UUID_NODE_LEN; i++)
p[10 + i] = uuid->node[i];
}
void
le_uuid_dec(void const *buf, struct uuid *uuid)
{
u_char const *p;
int i;
p = buf;
uuid->time_low = le32dec(p);
uuid->time_mid = le16dec(p + 4);
uuid->time_hi_and_version = le16dec(p + 6);
uuid->clock_seq_hi_and_reserved = p[8];
uuid->clock_seq_low = p[9];
for (i = 0; i < _UUID_NODE_LEN; i++)
uuid->node[i] = p[10 + i];
}
void
be_uuid_enc(void *buf, struct uuid const *uuid)
{
u_char *p;
int i;
p = buf;
be32enc(p, uuid->time_low);
be16enc(p + 4, uuid->time_mid);
be16enc(p + 6, uuid->time_hi_and_version);
p[8] = uuid->clock_seq_hi_and_reserved;
p[9] = uuid->clock_seq_low;
for (i = 0; i < _UUID_NODE_LEN; i++)
p[10 + i] = uuid->node[i];
}
void
be_uuid_dec(void const *buf, struct uuid *uuid)
{
u_char const *p;
int i;
p = buf;
uuid->time_low = be32dec(p);
uuid->time_mid = le16dec(p + 4);
uuid->time_hi_and_version = be16dec(p + 6);
uuid->clock_seq_hi_and_reserved = p[8];
uuid->clock_seq_low = p[9];
for (i = 0; i < _UUID_NODE_LEN; i++)
uuid->node[i] = p[10 + i];
}
int
parse_uuid(const char *str, struct uuid *uuid)
{
u_int c[11];
int n;
/* An empty string represents a nil UUID. */
if (*str == '\0') {
bzero(uuid, sizeof(*uuid));
return (0);
}
/* The UUID string representation has a fixed length. */
if (strlen(str) != 36)
return (EINVAL);
/*
* We only work with "new" UUIDs. New UUIDs have the form:
* 01234567-89ab-cdef-0123-456789abcdef
* The so called "old" UUIDs, which we don't support, have the form:
* 0123456789ab.cd.ef.01.23.45.67.89.ab
*/
if (str[8] != '-')
return (EINVAL);
n = sscanf(str, "%8x-%4x-%4x-%2x%2x-%2x%2x%2x%2x%2x%2x", c + 0, c + 1,
c + 2, c + 3, c + 4, c + 5, c + 6, c + 7, c + 8, c + 9, c + 10);
/* Make sure we have all conversions. */
if (n != 11)
return (EINVAL);
/* Successful scan. Build the UUID. */
uuid->time_low = c[0];
uuid->time_mid = c[1];
uuid->time_hi_and_version = c[2];
uuid->clock_seq_hi_and_reserved = c[3];
uuid->clock_seq_low = c[4];
for (n = 0; n < 6; n++)
uuid->node[n] = c[n + 5];
/* Check semantics... */
return (((c[3] & 0x80) != 0x00 && /* variant 0? */
(c[3] & 0xc0) != 0x80 && /* variant 1? */
(c[3] & 0xe0) != 0xc0) ? EINVAL : 0); /* variant 2? */
}