pw: set the user's home directory mode if it existed

The adduser(8) prompt allows one to set the mode of a new home
directory, but pw(8) doesn't honor the -M mode if the home directory
already exists at creation time.  It doesn't seem to make sense to
ignore the mode (which may lead to a security issue on the system being
configured) when we'll happily chown an existing directory, so fix the
inconsistency.

PR:		280099
Reviewed by:	des, jlduran (previous version)

(cherry picked from commit 6a7238fd7c)

usr.sbin/adduser/adduser.8

@@ -27,7 +27,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd April 11, 2024
+.Dd December 1, 2024
 .Dt ADDUSER 8
 .Os
 .Sh NAME
@@ -246,7 +246,9 @@ file can reference the internal variables of the
 script.
 .It Fl M Ar mode
 Create the home directory with permissions set to
-.Ar mode .
+.Ar mode ,
+modified by the current
+.Xr umask 2 .
 .It Fl N
 Do not read the default configuration file.
 .It Fl q

usr.sbin/pw/cpdir.c

@@ -49,13 +49,28 @@ copymkdir(int rootfd, char const * dir, int skelfd, mode_t mode, uid_t uid,
 	if (*dir == '/')
 		dir++;
 
-	if (mkdirat(rootfd, dir, mode) != 0 && errno != EEXIST) {
-		warn("mkdir(%s)", dir);
-		return;
+	if (mkdirat(rootfd, dir, mode) != 0) {
+		mode_t pumask;
+
+		if (errno != EEXIST) {
+			warn("mkdir(%s)", dir);
+			return;
+		}
+
+		pumask = umask(0);
+		umask(pumask);
+
+		if (fchmodat(rootfd, dir, mode & ~pumask,
+		    AT_SYMLINK_NOFOLLOW) == -1)
+			warn("chmod(%s)", dir);
 	}
-	fchownat(rootfd, dir, uid, gid, AT_SYMLINK_NOFOLLOW);
-	if (flags > 0)
-		chflagsat(rootfd, dir, flags, AT_SYMLINK_NOFOLLOW);
+
+	if (fchownat(rootfd, dir, uid, gid, AT_SYMLINK_NOFOLLOW) == -1)
+		warn("chown(%s)", dir);
+
+	if (flags > 0 && chflagsat(rootfd, dir, flags,
+	    AT_SYMLINK_NOFOLLOW) == -1)
+		warn("chflags(%s)", dir);
 
 	if (skelfd == -1)
 		return;