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Two-phase HDB commit via iprop log, + GC for log

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We used to update the iprop log and HDB in different orders depending on
the kadm5 operation, which then led to various race conditions.

The iprop log now functions as a two-phase commit (with roll forward)
log for HDB changes.  The log is auto-truncated, keeping the latest
entries that fit in a configurable maximum number of bytes (defaults to
50MB).  See the log-max-size parameter description in krb5.conf(5).

The iprop log format and the protocol remain backwards-compatible with
earlier versions of Heimdal.  This is NOT a flag-day; there is NO need
to update all the slaves at once with the master, though it is advisable
in general.  Rolling upgrades and downgrades should work.

The sequence of updates is now (with HDB and log open and locked):

a) check that the HDB operation will succeed if attempted,
b) append to iprop log and fsync() it,
c) write to HDB (which should fsync()),
d) mark last log record committed (no fsync in this case).

Every kadm5 write operation recover transactions not yet confirmed as
committed, thus there can be at most one unconfirmed commit on a master
KDC.

Reads via kadm5_get_principal() also attempt to lock the log, and if
successful, recover unconfirmed transactions; readers must have write
access and must win any race to lock the iprop log.

The ipropd-master daemon also attempts to recover unconfirmed
transactions when idle.

The log now starts with a nop record whose payload records the offset of
the logical end of the log: the end of the last confirmed committed
transaction.  This is kown as the "uber record".  Its purpose is
two-fold: act as the confirmation of committed transactions, and provide
an O(1) method of finding the end of the log (i.e., without having to
traverse the entire log front to back).

Two-phase commit makes all kadm5 writes single-operation atomic
transactions (though some kadm5 operations, such as renames of
principals, and changes to principals' aliases, use multiple low-level
HDB write operations, but still all in one transaction).  One can still
hold a lock on the HDB across many operations (e.g., by using the lock
command in a kadmin -l or calling kadm5_lock()) in order to push
multiple transactions in sequence, but this sequence will not be atomic
if the process or host crashes in the middle.

As before, HDB writes which do not go through the kadm5 API are excluded
from all of this, but there should be no such writes.

Lastly, the iprop-log(1) command is enhanced as follows:

 - The dump, last-version, truncate, and replay sub-commands now have an
   option to not lock the log.  This is useful for inspecting a running
   system's log file, especially on slave KDCs.

 - The dump, last-version, truncate, and replay sub-commands now take an
   optional iprop log file positional argument, so that they may be used
   to inspect log files other than the running system's
   configured/default log file.

Extensive code review and some re-writing for clarity by Viktor Dukhovni.
This commit is contained in:
Nicolas Williams
2015-05-29 15:53:40 -05:00
parent d774aeda38
commit 20df2c8706
33 changed files with 3274 additions and 804 deletions
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211
lib/kadm5/iprop-log.c
View File

@@ -46,11 +46,11 @@ get_kadmin_context(const char *config_file, char *realm)
kadm5_config_params conf;
krb5_error_code ret;
void *kadm_handle;
char *file = NULL;
char **files;
int aret;
if (config_file == NULL) {
char *file;
aret = asprintf(&file, "%s/kdc.conf", hdb_db_dir(context));
if (aret == -1 || file == NULL)
errx(1, "out of memory");
@@ -58,6 +58,7 @@ get_kadmin_context(const char *config_file, char *realm)
}
ret = krb5_prepend_config_files_default(config_file, &files);
free(file);
if (ret)
krb5_err(context, 1, ret, "getting configuration files");
@@ -102,7 +103,7 @@ static const char *op_names[] = {
"nop"
};
static void
static kadm5_ret_t
print_entry(kadm5_server_context *server_context,
uint32_t ver,
time_t timestamp,
@@ -112,29 +113,28 @@ print_entry(kadm5_server_context *server_context,
void *ctx)
{
char t[256];
const char *entry_kind = ctx;
int32_t mask;
int32_t nop_time;
uint32_t nop_ver;
hdb_entry ent;
krb5_principal source;
char *name1, *name2;
krb5_data data;
krb5_context scontext = server_context->context;
krb5_error_code ret;
krb5_data_zero(&data);
off_t end = krb5_storage_seek(sp, 0, SEEK_CUR) + len;
krb5_error_code ret;
strftime(t, sizeof(t), "%Y-%m-%d %H:%M:%S", localtime(&timestamp));
if((int)op < (int)kadm_get || (int)op > (int)kadm_nop) {
printf("unknown op: %d\n", op);
krb5_storage_seek(sp, end, SEEK_SET);
return;
return 0;
}
printf ("%s: ver = %u, timestamp = %s, len = %u\n",
op_names[op], ver, t, len);
printf ("%s%s: ver = %u, timestamp = %s, len = %u\n",
entry_kind, op_names[op], ver, t, len);
switch(op) {
case kadm_delete:
krb5_ret_principal(sp, &source);
@@ -261,12 +261,29 @@ print_entry(kadm5_server_context *server_context,
free_hdb_entry(&ent);
break;
case kadm_nop :
if (len == 16) {
uint64_t off;
krb5_ret_uint64(sp, &off);
printf("uberblock offset %llu ", (unsigned long long)off);
} else {
printf("nop");
}
if (len == 16 || len == 8) {
krb5_ret_int32(sp, &nop_time);
krb5_ret_uint32(sp, &nop_ver);
timestamp = nop_time;
strftime(t, sizeof(t), "%Y-%m-%d %H:%M:%S", localtime(&timestamp));
printf("timestamp %s version %u", t, nop_ver);
}
printf("\n");
break;
default:
abort();
}
krb5_data_free(&data);
krb5_storage_seek(sp, end, SEEK_SET);
return 0;
}
int
@@ -274,21 +291,61 @@ iprop_dump(struct dump_options *opt, int argc, char **argv)
{
kadm5_server_context *server_context;
krb5_error_code ret;
enum kadm_iter_opts iter_opts_1st = 0;
enum kadm_iter_opts iter_opts_2nd = 0;
char *desc_1st = "";
char *desc_2nd = "";
server_context = get_kadmin_context(opt->config_file_string,
opt->realm_string);
ret = kadm5_log_init (server_context);
if (ret)
krb5_err (context, 1, ret, "kadm5_log_init");
if (argc > 0) {
free(server_context->log_context.log_file);
server_context->log_context.log_file = strdup(argv[0]);
if (server_context->log_context.log_file == NULL)
krb5_err(context, 1, errno, "strdup");
}
ret = kadm5_log_foreach (server_context, print_entry, NULL);
if(ret)
if (opt->reverse_flag) {
iter_opts_1st = kadm_backward | kadm_unconfirmed;
iter_opts_2nd = kadm_backward | kadm_confirmed;
desc_1st = "unconfirmed ";
} else {
iter_opts_1st = kadm_forward | kadm_confirmed;
iter_opts_2nd = kadm_forward | kadm_unconfirmed;
desc_2nd = "unconfirmed";
}
if (opt->no_lock_flag) {
ret = kadm5_log_init_sharedlock(server_context, LOCK_NB);
if (ret == EAGAIN || ret == EWOULDBLOCK) {
warnx("Not locking the iprop log");
ret = kadm5_log_init_nolock(server_context);
if (ret)
krb5_err(context, 1, ret, "kadm5_log_init_nolock");
}
} else {
warnx("If this command appears to block, try the --no-lock option");
ret = kadm5_log_init_sharedlock(server_context, 0);
if (ret)
krb5_err(context, 1, ret, "kadm5_log_init_sharedlock");
}
ret = kadm5_log_foreach(server_context, iter_opts_1st,
NULL, print_entry, desc_1st);
if (ret)
krb5_warn(context, ret, "kadm5_log_foreach");
ret = kadm5_log_foreach(server_context, iter_opts_2nd,
NULL, print_entry, desc_2nd);
if (ret)
krb5_warn(context, ret, "kadm5_log_foreach");
ret = kadm5_log_end (server_context);
if (ret)
krb5_warn(context, ret, "kadm5_log_end");
kadm5_destroy(server_context);
return 0;
}
@@ -301,10 +358,38 @@ iprop_truncate(struct truncate_options *opt, int argc, char **argv)
server_context = get_kadmin_context(opt->config_file_string,
opt->realm_string);
ret = kadm5_log_truncate (server_context);
if (ret)
krb5_err (context, 1, ret, "kadm5_log_truncate");
if (argc > 0) {
free(server_context->log_context.log_file);
server_context->log_context.log_file = strdup(argv[0]);
if (server_context->log_context.log_file == NULL)
krb5_err(context, 1, errno, "strdup");
}
if (opt->keep_entries_integer < 0 &&
opt->max_bytes_integer < 0) {
opt->keep_entries_integer = 100;
opt->max_bytes_integer = 0;
}
if (opt->keep_entries_integer < 0)
opt->keep_entries_integer = 0;
if (opt->max_bytes_integer < 0)
opt->max_bytes_integer = 0;
if (opt->reset_flag) {
ret = kadm5_log_reinit(server_context);
} else {
ret = kadm5_log_init(server_context);
if (ret)
krb5_err(context, 1, ret, "kadm5_log_init");
ret = kadm5_log_truncate(server_context, opt->keep_entries_integer,
opt->max_bytes_integer);
}
if (ret)
krb5_err(context, 1, ret, "kadm5_log_truncate");
kadm5_log_signal_master(server_context);
kadm5_destroy(server_context);
return 0;
}
@@ -312,26 +397,72 @@ int
last_version(struct last_version_options *opt, int argc, char **argv)
{
kadm5_server_context *server_context;
char *alt_argv[2];
krb5_error_code ret;
uint32_t version;
size_t i;
server_context = get_kadmin_context(opt->config_file_string,
opt->realm_string);
ret = kadm5_log_init (server_context);
if (ret)
krb5_err (context, 1, ret, "kadm5_log_init");
if (argc == 0) {
alt_argv[0] = strdup(server_context->log_context.log_file);
alt_argv[1] = NULL;
if (alt_argv[0] == NULL)
krb5_err(context, 1, errno, "strdup");
argv = alt_argv;
argc = 1;
}
ret = kadm5_log_get_version (server_context, &version);
if (ret)
krb5_err (context, 1, ret, "kadm5_log_get_version");
for (i = 0; i < argc; i++) {
free(server_context->log_context.log_file);
server_context->log_context.log_file = strdup(argv[i]);
if (server_context->log_context.log_file == NULL)
krb5_err(context, 1, errno, "strdup");
ret = kadm5_log_end (server_context);
if (ret)
krb5_warn(context, ret, "kadm5_log_end");
if (opt->no_lock_flag) {
ret = kadm5_log_init_sharedlock(server_context, LOCK_NB);
if (ret == EAGAIN || ret == EWOULDBLOCK) {
warnx("Not locking the iprop log");
ret = kadm5_log_init_nolock(server_context);
if (ret)
krb5_err(context, 1, ret, "kadm5_log_init_nolock");
}
} else {
if (argc == 0)
warnx("If this command appears to block, try the "
"--no-lock option");
ret = kadm5_log_init_sharedlock(server_context, 0);
if (ret)
krb5_err(context, 1, ret, "kadm5_log_init_sharedlock");
}
printf("version: %lu\n", (unsigned long)version);
ret = kadm5_log_get_version (server_context, &version);
if (ret)
krb5_err (context, 1, ret, "kadm5_log_get_version");
ret = kadm5_log_end (server_context);
if (ret)
krb5_warn(context, ret, "kadm5_log_end");
printf("version: %lu\n", (unsigned long)version);
}
kadm5_destroy(server_context);
return 0;
}
int
signal_master(struct signal_options *opt, int argc, char **argv)
{
kadm5_server_context *server_context;
server_context = get_kadmin_context(opt->config_file_string,
opt->realm_string);
kadm5_log_signal_master(server_context);
kadm5_destroy(server_context);
return 0;
}
@@ -342,7 +473,7 @@ last_version(struct last_version_options *opt, int argc, char **argv)
int start_version = -1;
int end_version = -1;
static void
static kadm5_ret_t
apply_entry(kadm5_server_context *server_context,
uint32_t ver,
time_t timestamp,
@@ -357,18 +488,18 @@ apply_entry(kadm5_server_context *server_context,
if((opt->start_version_integer != -1 && ver < (uint32_t)opt->start_version_integer) ||
(opt->end_version_integer != -1 && ver > (uint32_t)opt->end_version_integer)) {
/* XXX skip this entry */
krb5_storage_seek(sp, len, SEEK_CUR);
return;
return 0;
}
printf ("ver %u... ", ver);
fflush (stdout);
ret = kadm5_log_replay (server_context,
op, ver, len, sp);
ret = kadm5_log_replay(server_context, op, ver, len, sp);
if (ret)
krb5_warn (server_context->context, ret, "kadm5_log_replay");
printf ("done\n");
return 0;
}
int
@@ -380,6 +511,13 @@ iprop_replay(struct replay_options *opt, int argc, char **argv)
server_context = get_kadmin_context(opt->config_file_string,
opt->realm_string);
if (argc > 0) {
free(server_context->log_context.log_file);
server_context->log_context.log_file = strdup(argv[0]);
if (server_context->log_context.log_file == NULL)
krb5_err(context, 1, errno, "strdup");
}
ret = server_context->db->hdb_open(context,
server_context->db,
O_RDWR | O_CREAT, 0600);
@@ -390,7 +528,9 @@ iprop_replay(struct replay_options *opt, int argc, char **argv)
if (ret)
krb5_err (context, 1, ret, "kadm5_log_init");
ret = kadm5_log_foreach (server_context, apply_entry, opt);
ret = kadm5_log_foreach(server_context,
kadm_forward | kadm_confirmed | kadm_unconfirmed,
NULL, apply_entry, opt);
if(ret)
krb5_warn(context, ret, "kadm5_log_foreach");
ret = kadm5_log_end (server_context);
@@ -400,6 +540,7 @@ iprop_replay(struct replay_options *opt, int argc, char **argv)
if (ret)
krb5_err (context, 1, ret, "db->close");
kadm5_destroy(server_context);
return 0;
}