diff -up Linux-PAM-1.3.1/modules/pam_keyinit/pam_keyinit.c.pam_keyinit-thread-safe Linux-PAM-1.3.1/modules/pam_keyinit/pam_keyinit.c

--- Linux-PAM-1.3.1/modules/pam_keyinit/pam_keyinit.c.pam_keyinit-thread-safe	2017-02-10 11:10:15.000000000 +0100

+++ Linux-PAM-1.3.1/modules/pam_keyinit/pam_keyinit.c	2022-04-25 12:10:28.071240439 +0200

@@ -20,6 +20,7 @@

 #include <security/pam_modutil.h>

 #include <security/pam_ext.h>

 #include <sys/syscall.h>

+#include <stdatomic.h>

 #define KEY_SPEC_SESSION_KEYRING	-3 /* ID for session keyring */

 #define KEY_SPEC_USER_KEYRING		-4 /* ID for UID-specific keyring */

@@ -30,12 +31,12 @@

 #define KEYCTL_REVOKE			3 /* revoke a key */

 #define KEYCTL_LINK			8 /* link a key into a keyring */

-static int my_session_keyring;

-static int session_counter;

-static int do_revoke;

-static int revoke_as_uid;

-static int revoke_as_gid;

-static int xdebug = 0;

+static _Thread_local int my_session_keyring = 0;

+static _Atomic int session_counter = 0;

+static _Thread_local int do_revoke = 0;

+static _Thread_local uid_t revoke_as_uid;

+static _Thread_local gid_t revoke_as_gid;

+static _Thread_local int xdebug = 0;

 static void debug(pam_handle_t *pamh, const char *fmt, ...)

 	__attribute__((format(printf, 2, 3)));

@@ -65,6 +66,33 @@ static int error(pam_handle_t *pamh, con

 	return PAM_SESSION_ERR;

 }

+static int pam_setreuid(uid_t ruid, uid_t euid)

+{

+#if defined(SYS_setreuid32)

+    return syscall(SYS_setreuid32, ruid, euid);

+#else

+    return syscall(SYS_setreuid, ruid, euid);

+#endif

+}

+

+static int pam_setregid(gid_t rgid, gid_t egid)

+{

+#if defined(SYS_setregid32)

+    return syscall(SYS_setregid32, rgid, egid);

+#else

+    return syscall(SYS_setregid, rgid, egid);

+#endif

+}

+

+static int pam_setresuid(uid_t ruid, uid_t euid, uid_t suid)

+{

+#if defined(SYS_setresuid32)

+    return syscall(SYS_setresuid32, ruid, euid, suid);

+#else

+    return syscall(SYS_setresuid, ruid, euid, suid);

+#endif

+}

+

 /*

  * initialise the session keyring for this process

  */

@@ -139,23 +167,25 @@ static void kill_keyrings(pam_handle_t *

 		/* switch to the real UID and GID so that we have permission to

 		 * revoke the key */

-		if (revoke_as_gid != old_gid && setregid(-1, revoke_as_gid) < 0)

+		if (revoke_as_gid != old_gid && pam_setregid(-1, revoke_as_gid) < 0)

 			error(pamh, "Unable to change GID to %d temporarily\n",

 			      revoke_as_gid);

-		if (revoke_as_uid != old_uid && setresuid(-1, revoke_as_uid, old_uid) < 0)

+		if (revoke_as_uid != old_uid && pam_setresuid(-1, revoke_as_uid, old_uid) < 0)

 			error(pamh, "Unable to change UID to %d temporarily\n",

 			      revoke_as_uid);

+			if (getegid() != old_gid && pam_setregid(-1, old_gid) < 0)

+				error(pamh, "Unable to change GID back to %d\n", old_gid);

 		syscall(__NR_keyctl,

 			KEYCTL_REVOKE,

 			my_session_keyring);

 		/* return to the orignal UID and GID (probably root) */

-		if (revoke_as_uid != old_uid && setreuid(-1, old_uid) < 0)

+		if (revoke_as_uid != old_uid && pam_setreuid(-1, old_uid) < 0)

 			error(pamh, "Unable to change UID back to %d\n", old_uid);

-		if (revoke_as_gid != old_gid && setregid(-1, old_gid) < 0)

+		if (revoke_as_gid != old_gid && pam_setregid(-1, old_gid) < 0)

 			error(pamh, "Unable to change GID back to %d\n", old_gid);

 		my_session_keyring = 0;

@@ -210,14 +240,14 @@ int pam_sm_open_session(pam_handle_t *pa

 	/* switch to the real UID and GID so that the keyring ends up owned by

 	 * the right user */

-	if (gid != old_gid && setregid(gid, -1) < 0) {

+	if (gid != old_gid && pam_setregid(gid, -1) < 0) {

 		error(pamh, "Unable to change GID to %d temporarily\n", gid);

 		return PAM_SESSION_ERR;

 	}

-	if (uid != old_uid && setreuid(uid, -1) < 0) {

+	if (uid != old_uid && pam_setreuid(uid, -1) < 0) {

 		error(pamh, "Unable to change UID to %d temporarily\n", uid);

-		if (setregid(old_gid, -1) < 0)

+		if (pam_setregid(old_gid, -1) < 0)

 			error(pamh, "Unable to change GID back to %d\n", old_gid);

 		return PAM_SESSION_ERR;

 	}

@@ -225,10 +255,10 @@ int pam_sm_open_session(pam_handle_t *pa

 	ret = init_keyrings(pamh, force);

 	/* return to the orignal UID and GID (probably root) */

-	if (uid != old_uid && setreuid(old_uid, -1) < 0)

+	if (uid != old_uid && pam_setreuid(old_uid, -1) < 0)

 		ret = error(pamh, "Unable to change UID back to %d\n", old_uid);

-	if (gid != old_gid && setregid(old_gid, -1) < 0)

+	if (gid != old_gid && pam_setregid(old_gid, -1) < 0)

 		ret = error(pamh, "Unable to change GID back to %d\n", old_gid);

 	return ret;