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BUG/MEDIUM: server/cli: Fix ABBA deadlock when fqdn is set from the CLI

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To perform servers resolution, the resolver's lock is first acquired then
the server's lock when necessary. However, when the fqdn is set via the CLI,
the opposite is performed. So, it is possible to experience an ABBA
deadlock.

To fix this bug, the server's lock is acquired and released for each
subcommand of "set server" with an exception when the fqdn is set. The
resolver's lock is first acquired. Of course, this means we must be sure to
have a resolver to lock.

This patch must be backported as far as 1.8.
This commit is contained in:
Christopher Faulet 2021-06-15 12:01:29 +02:00
parent a386e78823
commit c7b391aed2
2 changed files with 44 additions and 16 deletions
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2
reg-tests/server/cli_set_fdqn.vtc
View File

@ -27,7 +27,7 @@ haproxy h1 -conf {
haproxy h1 -cli {
send "set server test/www1 fqdn foo.fqdn"
expect ~ "could not update test/www1 FQDN by 'stats socket command'"
expect ~ "set server <b>/<s> fqdn failed because no resolution is configured."
send "show servers state test"
expect ~ "test 1 www1 ${s1_addr} .* - ${s1_port}"
} -wait

58
src/server.c
View File

@ -3906,14 +3906,15 @@ static int cli_parse_set_server(char **args, char *payload, struct appctx *appct
if (!sv)
return 1;
HA_SPIN_LOCK(SERVER_LOCK, &sv->lock);
if (strcmp(args[3], "weight") == 0) {
HA_SPIN_LOCK(SERVER_LOCK, &sv->lock);
warning = server_parse_weight_change_request(sv, args[4]);
HA_SPIN_UNLOCK(SERVER_LOCK, &sv->lock);
if (warning)
cli_err(appctx, warning);
}
else if (strcmp(args[3], "state") == 0) {
HA_SPIN_LOCK(SERVER_LOCK, &sv->lock);
if (strcmp(args[4], "ready") == 0)
srv_adm_set_ready(sv);
else if (strcmp(args[4], "drain") == 0)
@ -3922,8 +3923,10 @@ static int cli_parse_set_server(char **args, char *payload, struct appctx *appct
srv_adm_set_maint(sv);
else
cli_err(appctx, "'set server <srv> state' expects 'ready', 'drain' and 'maint'.\n");
HA_SPIN_UNLOCK(SERVER_LOCK, &sv->lock);
}
else if (strcmp(args[3], "health") == 0) {
HA_SPIN_LOCK(SERVER_LOCK, &sv->lock);
if (sv->track)
cli_err(appctx, "cannot change health on a tracking server.\n");
else if (strcmp(args[4], "up") == 0) {
@ -3940,8 +3943,10 @@ static int cli_parse_set_server(char **args, char *payload, struct appctx *appct
}
else
cli_err(appctx, "'set server <srv> health' expects 'up', 'stopping', or 'down'.\n");
HA_SPIN_UNLOCK(SERVER_LOCK, &sv->lock);
}
else if (strcmp(args[3], "agent") == 0) {
HA_SPIN_LOCK(SERVER_LOCK, &sv->lock);
if (!(sv->agent.state & CHK_ST_ENABLED))
cli_err(appctx, "agent checks are not enabled on this server.\n");
else if (strcmp(args[4], "up") == 0) {
@ -3954,6 +3959,7 @@ static int cli_parse_set_server(char **args, char *payload, struct appctx *appct
}
else
cli_err(appctx, "'set server <srv> agent' expects 'up' or 'down'.\n");
HA_SPIN_UNLOCK(SERVER_LOCK, &sv->lock);
}
else if (strcmp(args[3], "agent-addr") == 0) {
char *addr = NULL;
@ -3961,12 +3967,14 @@ static int cli_parse_set_server(char **args, char *payload, struct appctx *appct
if (strlen(args[4]) == 0) {
cli_err(appctx, "set server <b>/<s> agent-addr requires"
" an address and optionally a port.\n");
goto out_unlock;
goto out;
}
addr = args[4];
if (strcmp(args[5], "port") == 0)
port = args[6];
HA_SPIN_LOCK(SERVER_LOCK, &sv->lock);
warning = srv_update_agent_addr_port(sv, addr, port);
HA_SPIN_UNLOCK(SERVER_LOCK, &sv->lock);
if (warning)
cli_msg(appctx, LOG_WARNING, warning);
}
@ -3975,10 +3983,12 @@ static int cli_parse_set_server(char **args, char *payload, struct appctx *appct
if (strlen(args[4]) == 0) {
cli_err(appctx, "set server <b>/<s> agent-port requires"
" a port.\n");
goto out_unlock;
goto out;
}
port = args[4];
HA_SPIN_LOCK(SERVER_LOCK, &sv->lock);
warning = srv_update_agent_addr_port(sv, NULL, port);
HA_SPIN_UNLOCK(SERVER_LOCK, &sv->lock);
if (warning)
cli_msg(appctx, LOG_WARNING, warning);
}
@ -3996,12 +4006,14 @@ static int cli_parse_set_server(char **args, char *payload, struct appctx *appct
if (strlen(args[4]) == 0) {
cli_err(appctx, "set server <b>/<s> check-addr requires"
" an address and optionally a port.\n");
goto out_unlock;
goto out;
}
addr = args[4];
if (strcmp(args[5], "port") == 0)
port = args[6];
HA_SPIN_LOCK(SERVER_LOCK, &sv->lock);
warning = srv_update_check_addr_port(sv, addr, port);
HA_SPIN_UNLOCK(SERVER_LOCK, &sv->lock);
if (warning)
cli_msg(appctx, LOG_WARNING, warning);
}
@ -4010,10 +4022,12 @@ static int cli_parse_set_server(char **args, char *payload, struct appctx *appct
if (strlen(args[4]) == 0) {
cli_err(appctx, "set server <b>/<s> check-port requires"
" a port.\n");
goto out_unlock;
goto out;
}
port = args[4];
HA_SPIN_LOCK(SERVER_LOCK, &sv->lock);
warning = srv_update_check_addr_port(sv, NULL, port);
HA_SPIN_UNLOCK(SERVER_LOCK, &sv->lock);
if (warning)
cli_msg(appctx, LOG_WARNING, warning);
}
@ -4022,7 +4036,7 @@ static int cli_parse_set_server(char **args, char *payload, struct appctx *appct
char *port = NULL;
if (strlen(args[4]) == 0) {
cli_err(appctx, "set server <b>/<s> addr requires an address and optionally a port.\n");
goto out_unlock;
goto out;
}
else {
addr = args[4];
@ -4030,25 +4044,35 @@ static int cli_parse_set_server(char **args, char *payload, struct appctx *appct
if (strcmp(args[5], "port") == 0) {
port = args[6];
}
HA_SPIN_LOCK(SERVER_LOCK, &sv->lock);
warning = srv_update_addr_port(sv, addr, port, "stats socket command");
if (warning)
cli_msg(appctx, LOG_WARNING, warning);
srv_clr_admin_flag(sv, SRV_ADMF_RMAINT);
HA_SPIN_UNLOCK(SERVER_LOCK, &sv->lock);
}
else if (strcmp(args[3], "fqdn") == 0) {
if (!*args[4]) {
cli_err(appctx, "set server <b>/<s> fqdn requires a FQDN.\n");
goto out_unlock;
goto out;
}
if (!sv->resolvers) {
cli_err(appctx, "set server <b>/<s> fqdn failed because no resolution is configured.\n");
goto out;
}
if (sv->srvrq) {
cli_err(appctx, "set server <b>/<s> fqdn failed because SRV resolution is configured.\n");
goto out_unlock;
goto out;
}
HA_SPIN_LOCK(DNS_LOCK, &sv->resolvers->lock);
HA_SPIN_LOCK(SERVER_LOCK, &sv->lock);
/* ensure runtime resolver will process this new fqdn */
if (sv->flags & SRV_F_NO_RESOLUTION) {
sv->flags &= ~SRV_F_NO_RESOLUTION;
}
warning = srv_update_fqdn(sv, args[4], "stats socket command", 0);
warning = srv_update_fqdn(sv, args[4], "stats socket command", 1);
HA_SPIN_UNLOCK(SERVER_UNLOCK, &sv->lock);
HA_SPIN_UNLOCK(DNS_LOCK, &sv->resolvers->lock);
if (warning)
cli_msg(appctx, LOG_WARNING, warning);
}
@ -4057,16 +4081,21 @@ static int cli_parse_set_server(char **args, char *payload, struct appctx *appct
if (sv->ssl_ctx.ctx == NULL) {
cli_err(appctx, "'set server <srv> ssl' cannot be set. "
" default-server should define ssl settings\n");
goto out_unlock;
} else if (strcmp(args[4], "on") == 0) {
goto out;
}
HA_SPIN_LOCK(SERVER_LOCK, &sv->lock);
if (strcmp(args[4], "on") == 0) {
ssl_sock_set_srv(sv, 1);
} else if (strcmp(args[4], "off") == 0) {
ssl_sock_set_srv(sv, 0);
} else {
HA_SPIN_UNLOCK(SERVER_LOCK, &sv->lock);
cli_err(appctx, "'set server <srv> ssl' expects 'on' or 'off'.\n");
goto out_unlock;
goto out;
}
srv_cleanup_connections(sv);
HA_SPIN_UNLOCK(SERVER_LOCK, &sv->lock);
cli_msg(appctx, LOG_NOTICE, "server ssl setting updated.\n");
#else
cli_msg(appctx, LOG_NOTICE, "server ssl setting not supported.\n");
@ -4078,8 +4107,7 @@ static int cli_parse_set_server(char **args, char *payload, struct appctx *appct
"check-addr | check-port | fqdn | health | ssl | "
"state | weight\n");
}
out_unlock:
HA_SPIN_UNLOCK(SERVER_LOCK, &sv->lock);
out:
return 1;
}