Andrew, could you please consider adding this patch to your 2.6.25 patch series?
This is the third version of the patch in which I cleaned up and fixed quite some stuff according to feedback from Ted. I assume this version is OK, since I didn't received any further feedback since two weeks: http://lkml.org/lkml/2007/11/4/128. Thanks, Helge ------- Title: Add time-based RFC 4122 UUID generator The current Linux kernel currently contains the generate_random_uuid() function, which creates - based on RFC 4122 - truly random UUIDs and provides them to userspace through /proc/sys/kernel/random/boot_id and /proc/sys/kernel/random/uuid. This patch additionally adds the "Time-based UUID" variant of RFC 4122, with which userspace applications can easily get real unique time-based UUIDs through /proc/sys/kernel/random/uuid_time. A new /proc/sys/kernel/random/uuid_time_clockseq sysfs entry is available, so that the clock_seq value can be retained across system bootups (which is required by RFC 4122). The attached implementation uses getnstimeofday() to get very fine-grained granularity. This helps, so that userspace tools can get a lot more UUIDs (if needed) per time than before. A mutex takes care of the proper locking against a mistaken double creation of UUIDs for simultanious running processes. Signed-off-by: Helge Deller <[EMAIL PROTECTED]> drivers/char/random.c | 205 ++++++++++++++++++++++++++++++++++++++++++++----- include/linux/sysctl.h | 5 - 2 files changed, 190 insertions(+), 20 deletions(-) diff --git a/drivers/char/random.c b/drivers/char/random.c index 5fee056..fc48c29 100644 --- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -6,6 +6,9 @@ * Copyright Theodore Ts'o, 1994, 1995, 1996, 1997, 1998, 1999. All * rights reserved. * + * Time based UUID (RFC 4122) generator: + * Copyright Helge Deller <[EMAIL PROTECTED]>, 2007 + * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: @@ -239,6 +242,7 @@ #include <linux/spinlock.h> #include <linux/percpu.h> #include <linux/cryptohash.h> +#include <linux/if_arp.h> #include <asm/processor.h> #include <asm/uaccess.h> @@ -1174,12 +1178,169 @@ EXPORT_SYMBOL(generate_random_uuid); static int min_read_thresh = 8, min_write_thresh; static int max_read_thresh = INPUT_POOL_WORDS * 32; static int max_write_thresh = INPUT_POOL_WORDS * 32; -static char sysctl_bootid[16]; +static unsigned char sysctl_bootid[16] __read_mostly; /* - * These functions is used to return both the bootid UUID, and random - * UUID. The difference is in whether table->data is NULL; if it is, - * then a new UUID is generated and returned to the user. + * Helper functions and variables for time based UUID generator + */ +static unsigned int clock_seq; +static const unsigned int clock_seq_max = 0x3fff; /* 14 bits */ +static int clock_seq_initialized __read_mostly; + +static void init_clockseq(void) +{ + get_random_bytes(&clock_seq, sizeof(clock_seq)); + clock_seq &= clock_seq_max; + clock_seq_initialized = 1; +} + +static int proc_dointvec_clockseq(struct ctl_table *table, int write, + struct file *filp, void __user *buffer, + size_t *lenp, loff_t *ppos) +{ + int ret; + + if (!write && !clock_seq_initialized) + init_clockseq(); + + ret = proc_dointvec(table, write, filp, buffer, lenp, ppos); + + if (write && ret >= 0) { + clock_seq_initialized = 1; + clock_seq &= clock_seq_max; + } + + return ret; +} + +/* + * Generate time based UUID (RFC 4122) + * + * This function is protected with a mutex to ensure system-wide + * uniqiness of the new time based UUID. + */ +static void generate_random_uuid_time(unsigned char uuid_out[16]) +{ + static DEFINE_MUTEX(uuid_mutex); + static u64 last_time_all; + static unsigned int clock_seq_started; + static unsigned char last_mac[ETH_ALEN]; + + struct timespec ts; + u64 time_all; + unsigned char *found_mac = NULL; + struct net_device *d __maybe_unused; + int inc_clock_seq = 0; + + mutex_lock(&uuid_mutex); + + /* Get the spatially unique node identifier */ +#ifdef CONFIG_NET + read_lock(&dev_base_lock); + for_each_netdev(&init_net, d) { + if (d->type == ARPHRD_ETHER && d->addr_len == ETH_ALEN + && d != init_net.loopback_dev) { + if (!memcmp(&last_mac, d->dev_addr, ETH_ALEN)) { + found_mac = last_mac; + break; + } + if (!found_mac) + found_mac = d->dev_addr; + } + } + if (found_mac) + memcpy(&uuid_out[10], found_mac, ETH_ALEN); + read_unlock(&dev_base_lock); +#endif + if (unlikely(!found_mac)) { + /* use bootid's nodeID if no network interface found */ + if (sysctl_bootid[8] == 0) + generate_random_uuid(sysctl_bootid); + memcpy(&uuid_out[10], &sysctl_bootid[10], ETH_ALEN); + } + /* if MAC/NodeID changed, create a new clock_seq value */ + if (unlikely(found_mac != last_mac && + memcmp(&last_mac, &uuid_out[10], ETH_ALEN))) { + memcpy(&last_mac, &uuid_out[10], ETH_ALEN); + inc_clock_seq = 1; + } + + /* Determine 60-bit timestamp value. For UUID version 1, this is + * represented by Coordinated Universal Time (UTC) as a count of 100- + * nanosecond intervals since 00:00:00.00, 15 October 1582 (the date of + * Gregorian reform to the Christian calendar). + */ +advance_time: + getnstimeofday(&ts); + time_all = ((u64) ts.tv_sec) * (NSEC_PER_SEC/100); + time_all += ts.tv_nsec / 100; + + /* add offset from Gregorian Calendar to Jan 1 1970 */ + time_all += 12219292800000ULL * (NSEC_PER_MSEC/100); + time_all &= 0x0fffffffffffffffULL; /* limit to 60 bits */ + + /* Determine clock sequence (max. 14 bit) */ + if (unlikely(!clock_seq_initialized)) { + init_clockseq(); + clock_seq_started = clock_seq; + } else { + if (unlikely(inc_clock_seq || time_all <= last_time_all)) { + clock_seq = (clock_seq+1) & clock_seq_max; + if (unlikely(clock_seq == clock_seq_started)) { + clock_seq = (clock_seq-1) & clock_seq_max; + goto advance_time; + } + } else + clock_seq_started = clock_seq; + } + last_time_all = time_all; + + /* Fill in timestamp and clock_seq values */ + uuid_out[3] = (u8) time_all; + uuid_out[2] = (u8) (time_all >> 8); + uuid_out[1] = (u8) (time_all >> 16); + uuid_out[0] = (u8) (time_all >> 24); + uuid_out[5] = (u8) (time_all >> 32); + uuid_out[4] = (u8) (time_all >> 40); + uuid_out[7] = (u8) (time_all >> 48); + uuid_out[6] = (u8) (time_all >> 56); + + uuid_out[8] = clock_seq >> 8; + uuid_out[9] = clock_seq & 0xff; + + /* Set UUID version to 1 --- time-based generation */ + uuid_out[6] = (uuid_out[6] & 0x0F) | 0x10; + /* Set the UUID variant to DCE */ + uuid_out[8] = (uuid_out[8] & 0x3F) | 0x80; + + mutex_unlock(&uuid_mutex); +} + + +/* + * Get UUID based on requested type. + */ +static unsigned char *get_uuid(void *extra1, unsigned char *uuid) +{ + switch ((int) extra1) { + case RANDOM_BOOT_ID: + uuid = sysctl_bootid; + if (unlikely(uuid[8] == 0)) + generate_random_uuid(uuid); + break; + case RANDOM_UUID: + generate_random_uuid(uuid); + break; + case RANDOM_UUID_TIME: + generate_random_uuid_time(uuid); + break; + } + return uuid; +} + +/* + * These functions are used to return the bootid UUID, random UUID and + * time based UUID. * * If the user accesses this via the proc interface, it will be returned * as an ASCII string in the standard UUID format. If accesses via the @@ -1191,13 +1352,13 @@ static int proc_do_uuid(ctl_table *table, int write, struct file *filp, ctl_table fake_table; unsigned char buf[64], tmp_uuid[16], *uuid; - uuid = table->data; - if (!uuid) { - uuid = tmp_uuid; - uuid[8] = 0; + /* random/time UUIDs need to be read completely at once */ + if ((int)table->extra1 != RANDOM_BOOT_ID && *ppos > 0) { + *lenp = 0; + return 0; } - if (uuid[8] == 0) - generate_random_uuid(uuid); + + uuid = get_uuid(table->extra1, tmp_uuid); sprintf(buf, "%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-" "%02x%02x%02x%02x%02x%02x", @@ -1221,13 +1382,7 @@ static int uuid_strategy(ctl_table *table, int __user *name, int nlen, if (!oldval || !oldlenp) return 1; - uuid = table->data; - if (!uuid) { - uuid = tmp_uuid; - uuid[8] = 0; - } - if (uuid[8] == 0) - generate_random_uuid(uuid); + uuid = get_uuid(table->extra1, tmp_uuid); if (get_user(len, oldlenp)) return -EFAULT; @@ -1284,11 +1439,11 @@ ctl_table random_table[] = { { .ctl_name = RANDOM_BOOT_ID, .procname = "boot_id", - .data = &sysctl_bootid, .maxlen = 16, .mode = 0444, .proc_handler = &proc_do_uuid, .strategy = &uuid_strategy, + .extra1 = (void *) RANDOM_BOOT_ID, }, { .ctl_name = RANDOM_UUID, @@ -1297,6 +1452,20 @@ ctl_table random_table[] = { .mode = 0444, .proc_handler = &proc_do_uuid, .strategy = &uuid_strategy, + .extra1 = (void *) RANDOM_UUID, + }, + { + .procname = "uuid_time", + .mode = 0444, + .proc_handler = &proc_do_uuid, + .extra1 = (void *) RANDOM_UUID_TIME, + }, + { + .procname = "uuid_time_clockseq", + .data = &clock_seq, + .maxlen = sizeof(unsigned int), + .mode = 0644, + .proc_handler = &proc_dointvec_clockseq, }, { .ctl_name = 0 } }; diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h index e99171f..dd09d97 100644 --- a/include/linux/sysctl.h +++ b/include/linux/sysctl.h @@ -248,8 +248,9 @@ enum RANDOM_ENTROPY_COUNT=2, RANDOM_READ_THRESH=3, RANDOM_WRITE_THRESH=4, - RANDOM_BOOT_ID=5, - RANDOM_UUID=6 + RANDOM_BOOT_ID=5, /* rfc4122 version 4, boot UUID */ + RANDOM_UUID=6, /* rfc4122 version 4, random-based */ + RANDOM_UUID_TIME=7 /* rfc4122 version 1, time-based */ }; /* /proc/sys/kernel/pty */ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
