Merge pull request #20968 from poettering/homed-pin

homed: pin+lock homes while logged in + keep trying to unmount on logging out + optionally drop caches on logging out

src/basic/socket-util.c

@@ -551,7 +551,7 @@ int getpeername_pretty(int fd, bool include_port, char **ret) {
                 return -errno;
 
         if (sa.sa.sa_family == AF_UNIX) {
-                struct ucred ucred = {};
+                struct ucred ucred = UCRED_INVALID;
 
                 /* UNIX connection sockets are anonymous, so let's use
                  * PID/UID as pretty credentials instead */

src/basic/socket-util.h

@@ -327,3 +327,6 @@ static inline int socket_set_recvfragsize(int fd, int af, bool b) {
 }
 
 int socket_get_mtu(int fd, int af, size_t *ret);
+
+/* an initializer for struct ucred that initialized all fields to the invalid value appropriate for each */
+#define UCRED_INVALID { .pid = 0, .uid = UID_INVALID, .gid = GID_INVALID }

src/basic/user-util.c

@@ -1085,3 +1085,14 @@ int is_this_me(const char *username) {
 
         return uid == getuid();
 }
+
+const char *get_home_root(void) {
+        const char *e;
+
+        /* For debug purposes allow overriding where we look for home dirs */
+        e = secure_getenv("SYSTEMD_HOME_ROOT");
+        if (e && path_is_absolute(e) && path_is_normalized(e))
+                return e;
+
+        return "/home";
+}

src/basic/user-util.h

@@ -112,6 +112,8 @@ bool is_nologin_shell(const char *shell);
 
 int is_this_me(const char *username);
 
+const char *get_home_root(void);
+
 /* A locked *and* invalid password for "struct spwd"'s .sp_pwdp and "struct passwd"'s .pw_passwd field */
 #define PASSWORD_LOCKED_AND_INVALID "!*"