From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 From: Martin Wilck Date: Tue, 22 Aug 2023 22:23:29 +0200 Subject: [PATCH] libmultipath: never allocate an alias that's already taken If the bindings file is changed in a way that multipathd can't handle (e.g. by swapping the aliases of two maps), multipathd must not try to re-use an alias that is already used by another map. Creating or renaming a map with such an alias will fail. We already avoid this for some cases, but not for all. Fix it. Signed-off-by: Martin Wilck Cc: David Bond Reviewed-by: Benjamin Marzinski Signed-off-by: Benjamin Marzinski --- libmultipath/alias.c | 31 +++++++++++++++++++++++-------- tests/alias.c | 2 +- 2 files changed, 24 insertions(+), 9 deletions(-) diff --git a/libmultipath/alias.c b/libmultipath/alias.c index 68f5d848..3e3dfe98 100644 --- a/libmultipath/alias.c +++ b/libmultipath/alias.c @@ -120,7 +120,7 @@ static bool alias_already_taken(const char *alias, const char *map_wwid) if (dm_get_uuid(alias, wwid, sizeof(wwid)) == 0 && strncmp(map_wwid, wwid, sizeof(wwid)) == 0) return false; - condlog(3, "%s: alias '%s' already taken, but not in bindings file. reselecting alias", + condlog(3, "%s: alias '%s' already taken, reselecting alias", map_wwid, alias); return true; } @@ -359,12 +359,11 @@ char *get_user_friendly_alias(const char *wwid, const char *file, const char *al rlookup_binding(f, buff, alias_old); if (strlen(buff) > 0) { - /* if buff is our wwid, it's already - * allocated correctly - */ + /* If buff is our wwid, it's already allocated correctly. */ if (strcmp(buff, wwid) == 0) { alias = strdup(alias_old); goto out; + } else { condlog(0, "alias %s already bound to wwid %s, cannot reuse", alias_old, buff); @@ -372,19 +371,35 @@ char *get_user_friendly_alias(const char *wwid, const char *file, const char *al } } - id = lookup_binding(f, wwid, &alias, NULL, 0); + /* + * Look for an existing alias in the bindings file. + * Pass prefix = NULL, so lookup_binding() won't try to allocate a new id. + */ + lookup_binding(f, wwid, &alias, NULL, 0); if (alias) { - condlog(3, "Use existing binding [%s] for WWID [%s]", - alias, wwid); + if (alias_already_taken(alias, wwid)) { + free(alias); + alias = NULL; + } else + condlog(3, "Use existing binding [%s] for WWID [%s]", + alias, wwid); goto out; } - /* allocate the existing alias in the bindings file */ + /* alias_old is already taken by our WWID, update bindings file. */ id = scan_devname(alias_old, prefix); new_alias: if (id <= 0) { + /* + * no existing alias was provided, or allocating it + * failed. Try a new one. + */ id = lookup_binding(f, wwid, &alias, prefix, 1); + if (id == 0 && alias_already_taken(alias, wwid)) { + free(alias); + alias = NULL; + } if (id <= 0) goto out; else diff --git a/tests/alias.c b/tests/alias.c index 3ca6c28b..11f209e0 100644 --- a/tests/alias.c +++ b/tests/alias.c @@ -398,7 +398,7 @@ static void mock_self_alias(const char *alias, const char *wwid) will_return(__wrap_dm_get_uuid, wwid); } -#define USED_STR(alias_str, wwid_str) wwid_str ": alias '" alias_str "' already taken, but not in bindings file. reselecting alias\n" +#define USED_STR(alias_str, wwid_str) wwid_str ": alias '" alias_str "' already taken, reselecting alias\n" static void mock_failed_alias(const char *alias, char *msg) {