From e714eb26fddc8768a8de279d1de3ffedab35929e Mon Sep 17 00:00:00 2001

From: Benjamin Marzinski <bmarzins@redhat.com>

Date: Fri, 5 Mar 2021 21:40:57 -0600

Subject: [PATCH] libmultipath: check if user_friendly_name is in use

If there are multipath devices that have user_friendly_names but do not

have their bindings in the bindings_file, get_user_friendly_alias() can

currently give out those names again. This can result in an incorrect

entry in the bindings file, and a device that gets created with a WWID

alias instead of a user_friendly_name. This situation can happen after

the pivot root, if a multipath device is created in the initramfs.  If

this device doesn't have a binding in the regular filesystem

bindings_file and a new multipath device is created before it can add

its binding, the new device can steal that user_friendly_name during

multipathd's initial configure.

To solve this, get_user_friendly_alias() now calls lookup_binding() with

a new paramter, telling it to check if the id it found is already in use

by a diffent device. If so, lookup_binding() will continue to check open

ids, until it finds one that it not currently in use by a dm device.

---

 libmultipath/alias.c | 48 +++++++++++++++++++++++++++++++++++++++++---

 tests/alias.c        | 22 ++++++++++----------

 2 files changed, 56 insertions(+), 14 deletions(-)

diff --git a/libmultipath/alias.c b/libmultipath/alias.c

index 14401cae..01f737f4 100644

--- a/libmultipath/alias.c

+++ b/libmultipath/alias.c

@@ -17,6 +17,7 @@

 #include "vector.h"

 #include "checkers.h"

 #include "structs.h"

+#include "devmapper.h"

 /*

@@ -104,6 +105,28 @@ scan_devname(const char *alias, const char *prefix)

 	return n;

 }

+static int

+id_already_taken(int id, const char *prefix, const char *map_wwid)

+{

+	char alias[LINE_MAX];

+

+	if (format_devname(alias, id, LINE_MAX, prefix) < 0)

+		return 0;

+

+	if (dm_map_present(alias)) {

+		char wwid[WWID_SIZE];

+

+		/* If both the name and the wwid match, then it's fine.*/

+		if (dm_get_uuid(alias, wwid, sizeof(wwid)) == 0 &&

+		    strncmp(map_wwid, wwid, sizeof(wwid)) == 0)

+			return 0;

+		condlog(3, "%s: alias '%s' already taken, but not in bindings file. reselecting alias", map_wwid, alias);

+		return 1;

+	}

+	return 0;

+}

+

+

 /*

  * Returns: 0   if matching entry in WWIDs file found

  *         -1   if an error occurs

@@ -113,7 +136,7 @@ scan_devname(const char *alias, const char *prefix)

  */

 static int

 lookup_binding(FILE *f, const char *map_wwid, char **map_alias,

-	       const char *prefix)

+	       const char *prefix, int check_if_taken)

 {

 	char buf[LINE_MAX];

 	unsigned int line_nr = 0;

@@ -168,12 +191,31 @@ lookup_binding(FILE *f, const char *map_wwid, char **map_alias,

 			return 0;

 		}

 	}

+	if (!prefix && check_if_taken)

+		id = -1;

 	if (id >= smallest_bigger_id) {

 		if (biggest_id < INT_MAX)

 			id = biggest_id + 1;

 		else

 			id = -1;

 	}

+	if (id > 0 && check_if_taken) {

+		while(id_already_taken(id, prefix, map_wwid)) {

+			if (id == INT_MAX) {

+				id = -1;

+				break;

+			}

+			id++;

+			if (id == smallest_bigger_id) {

+				if (biggest_id == INT_MAX) {

+					id = -1;

+					break;

+				}

+				if (biggest_id >= smallest_bigger_id)

+					id = biggest_id + 1;

+			}

+		}

+	}

 	if (id < 0) {

 		condlog(0, "no more available user_friendly_names");

 		return -1;

@@ -316,7 +358,7 @@ use_existing_alias (const char *wwid, const char *file, const char *alias_old,

 		goto out;

 	}

-	id = lookup_binding(f, wwid, &alias, NULL);

+	id = lookup_binding(f, wwid, &alias, NULL, 0);

 	if (alias) {

 		condlog(3, "Use existing binding [%s] for WWID [%s]",

 			alias, wwid);

@@ -373,7 +415,7 @@ get_user_friendly_alias(const char *wwid, const char *file, const char *prefix,

 		return NULL;

 	}

-	id = lookup_binding(f, wwid, &alias, prefix);

+	id = lookup_binding(f, wwid, &alias, prefix, 1);

 	if (id < 0) {

 		fclose(f);

 		return NULL;

diff --git a/tests/alias.c b/tests/alias.c

index 30414db0..ab1a9325 100644

--- a/tests/alias.c

+++ b/tests/alias.c

@@ -356,7 +356,7 @@ static void lb_empty(void **state)

 	will_return(__wrap_fgets, NULL);

 	expect_condlog(3, "No matching wwid [WWID0] in bindings file.\n");

-	rc = lookup_binding(NULL, "WWID0", &alias, NULL);

+	rc = lookup_binding(NULL, "WWID0", &alias, NULL, 0);

 	assert_int_equal(rc, 1);

 	assert_ptr_equal(alias, NULL);

 }

@@ -369,7 +369,7 @@ static void lb_match_a(void **state)

 	will_return(__wrap_fgets, "MPATHa WWID0\n");

 	expect_condlog(3, "Found matching wwid [WWID0] in bindings file."

 		       " Setting alias to MPATHa\n");

-	rc = lookup_binding(NULL, "WWID0", &alias, "MPATH");

+	rc = lookup_binding(NULL, "WWID0", &alias, "MPATH", 0);

 	assert_int_equal(rc, 0);

 	assert_ptr_not_equal(alias, NULL);

 	assert_string_equal(alias, "MPATHa");

@@ -384,7 +384,7 @@ static void lb_nomatch_a(void **state)

 	will_return(__wrap_fgets, "MPATHa WWID0\n");

 	will_return(__wrap_fgets, NULL);

 	expect_condlog(3, "No matching wwid [WWID1] in bindings file.\n");

-	rc = lookup_binding(NULL, "WWID1", &alias, "MPATH");

+	rc = lookup_binding(NULL, "WWID1", &alias, "MPATH", 0);

 	assert_int_equal(rc, 2);

 	assert_ptr_equal(alias, NULL);

 }

@@ -398,7 +398,7 @@ static void lb_match_c(void **state)

 	will_return(__wrap_fgets, "MPATHc WWID1\n");

 	expect_condlog(3, "Found matching wwid [WWID1] in bindings file."

 		       " Setting alias to MPATHc\n");

-	rc = lookup_binding(NULL, "WWID1", &alias, "MPATH");

+	rc = lookup_binding(NULL, "WWID1", &alias, "MPATH", 0);

 	assert_int_equal(rc, 0);

 	assert_ptr_not_equal(alias, NULL);

 	assert_string_equal(alias, "MPATHc");

@@ -414,7 +414,7 @@ static void lb_nomatch_a_c(void **state)

 	will_return(__wrap_fgets, "MPATHc WWID1\n");

 	will_return(__wrap_fgets, NULL);

 	expect_condlog(3, "No matching wwid [WWID2] in bindings file.\n");

-	rc = lookup_binding(NULL, "WWID2", &alias, "MPATH");

+	rc = lookup_binding(NULL, "WWID2", &alias, "MPATH", 0);

 	assert_int_equal(rc, 2);

 	assert_ptr_equal(alias, NULL);

 }

@@ -428,7 +428,7 @@ static void lb_nomatch_c_a(void **state)

 	will_return(__wrap_fgets, "MPATHa WWID0\n");

 	will_return(__wrap_fgets, NULL);

 	expect_condlog(3, "No matching wwid [WWID2] in bindings file.\n");

-	rc = lookup_binding(NULL, "WWID2", &alias, "MPATH");

+	rc = lookup_binding(NULL, "WWID2", &alias, "MPATH", 0);

 	assert_int_equal(rc, 2);

 	assert_ptr_equal(alias, NULL);

 }

@@ -443,7 +443,7 @@ static void lb_nomatch_a_b(void **state)

 	will_return(__wrap_fgets, "MPATHb WWID1\n");

 	will_return(__wrap_fgets, NULL);

 	expect_condlog(3, "No matching wwid [WWID2] in bindings file.\n");

-	rc = lookup_binding(NULL, "WWID2", &alias, "MPATH");

+	rc = lookup_binding(NULL, "WWID2", &alias, "MPATH", 0);

 	assert_int_equal(rc, 3);

 	assert_ptr_equal(alias, NULL);

 }

@@ -459,7 +459,7 @@ static void lb_nomatch_a_b_bad(void **state)

 	will_return(__wrap_fgets, NULL);

 	expect_condlog(3, "Ignoring malformed line 3 in bindings file\n");

 	expect_condlog(3, "No matching wwid [WWID2] in bindings file.\n");

-	rc = lookup_binding(NULL, "WWID2", &alias, "MPATH");

+	rc = lookup_binding(NULL, "WWID2", &alias, "MPATH", 0);

 	assert_int_equal(rc, 3);

 	assert_ptr_equal(alias, NULL);

 }

@@ -474,7 +474,7 @@ static void lb_nomatch_b_a(void **state)

 	will_return(__wrap_fgets, "MPATHa WWID0\n");

 	will_return(__wrap_fgets, NULL);

 	expect_condlog(3, "No matching wwid [WWID2] in bindings file.\n");

-	rc = lookup_binding(NULL, "WWID2", &alias, "MPATH");

+	rc = lookup_binding(NULL, "WWID2", &alias, "MPATH", 0);

 	assert_int_equal(rc, 27);

 	assert_ptr_equal(alias, NULL);

 }

@@ -490,7 +490,7 @@ static void lb_nomatch_int_max(void **state)

 	will_return(__wrap_fgets, "MPATHa WWID0\n");

 	will_return(__wrap_fgets, NULL);

 	expect_condlog(0, "no more available user_friendly_names\n");

-	rc = lookup_binding(NULL, "WWID2", &alias, "MPATH");

+	rc = lookup_binding(NULL, "WWID2", &alias, "MPATH", 0);

 	assert_int_equal(rc, -1);

 	assert_ptr_equal(alias, NULL);

 }

@@ -505,7 +505,7 @@ static void lb_nomatch_int_max_m1(void **state)

 	will_return(__wrap_fgets, "MPATHa WWID0\n");

 	will_return(__wrap_fgets, NULL);

 	expect_condlog(3, "No matching wwid [WWID2] in bindings file.\n");

-	rc = lookup_binding(NULL, "WWID2", &alias, "MPATH");

+	rc = lookup_binding(NULL, "WWID2", &alias, "MPATH", 0);

 	assert_int_equal(rc, INT_MAX);

 	assert_ptr_equal(alias, NULL);

 }

-- 

2.17.2