openwrt/package/network/services/dropbear/patches/100-pubkey_path.patch

--- a/svr-authpubkey.c
+++ b/svr-authpubkey.c
@@ -77,6 +77,13 @@ static void send_msg_userauth_pk_ok(cons
 		const unsigned char* keyblob, unsigned int keybloblen);
 static int checkfileperm(char * filename);
 
+static const char * const global_authkeys_dir = "/etc/dropbear";
+static const int        n_global_authkeys_dir = 14; /* + 1 extra byte */
+static const char * const user_authkeys_dir = ".ssh";
+static const int        n_user_authkeys_dir = 5; /* + 1 extra byte */
+static const char * const authkeys_file = "authorized_keys";
+static const int        n_authkeys_file = 16; /* + 1 extra byte */
+
 /* process a pubkey auth request, sending success or failure message as
  * appropriate */
 void svr_auth_pubkey(int valid_user) {
@@ -439,14 +446,21 @@ static int checkpubkey(const char* keyal
 	if (checkpubkeyperms() == DROPBEAR_FAILURE) {
 		TRACE(("bad authorized_keys permissions, or file doesn't exist"))
 	} else {
-		/* we don't need to check pw and pw_dir for validity, since
-		 * its been done in checkpubkeyperms. */
-		len = strlen(ses.authstate.pw_dir);
-		/* allocate max required pathname storage,
-		 * = path + "/.ssh/authorized_keys" + '\0' = pathlen + 22 */
-		filename = m_malloc(len + 22);
-		snprintf(filename, len + 22, "%s/.ssh/authorized_keys",
-					ses.authstate.pw_dir);
+		if (ses.authstate.pw_uid == 0) {
+			len = n_global_authkeys_dir + n_authkeys_file;
+			filename = m_malloc(len);
+			snprintf(filename, len, "%s/%s", global_authkeys_dir, authkeys_file);
+		} else {
+			/* we don't need to check pw and pw_dir for validity, since
+			 * its been done in checkpubkeyperms. */
+			len = strlen(ses.authstate.pw_dir);
+			/* allocate max required pathname storage,
+			 * = path + "/.ssh/authorized_keys" + '\0' = pathlen + 22 */
+			len += n_user_authkeys_dir + n_authkeys_file + 1;
+			filename = m_malloc(len);
+			snprintf(filename, len, "%s/%s/%s", ses.authstate.pw_dir,
+			        user_authkeys_dir, authkeys_file);
+		}
 
 		authfile = fopen(filename, "r");
 		if (!authfile) {
@@ -520,27 +534,41 @@ static int checkpubkeyperms() {
 		goto out;
 	}
 
-	/* allocate max required pathname storage,
-	 * = path + "/.ssh/authorized_keys" + '\0' = pathlen + 22 */
-	len += 22;
-	filename = m_malloc(len);
-	strlcpy(filename, ses.authstate.pw_dir, len);
+	if (ses.authstate.pw_uid == 0) {
+		if (checkfileperm(global_authkeys_dir) != DROPBEAR_SUCCESS) {
+			goto out;
+		}
 
-	/* check ~ */
-	if (checkfileperm(filename) != DROPBEAR_SUCCESS) {
-		goto out;
-	}
+		len = n_global_authkeys_dir + n_authkeys_file;
+		filename = m_malloc(len);
 
-	/* check ~/.ssh */
-	strlcat(filename, "/.ssh", len);
-	if (checkfileperm(filename) != DROPBEAR_SUCCESS) {
-		goto out;
-	}
+		snprintf(filename, len, "%s/%s", global_authkeys_dir, authkeys_file);
+		if (checkfileperm(filename) != DROPBEAR_SUCCESS) {
+			goto out;
+		}
+	} else {
+		/* check ~ */
+		if (checkfileperm(ses.authstate.pw_dir) != DROPBEAR_SUCCESS) {
+			goto out;
+		}
 
-	/* now check ~/.ssh/authorized_keys */
-	strlcat(filename, "/authorized_keys", len);
-	if (checkfileperm(filename) != DROPBEAR_SUCCESS) {
-		goto out;
+		/* allocate max required pathname storage,
+		 * = path + "/.ssh/authorized_keys" + '\0' = pathlen + 22 */
+		len += n_user_authkeys_dir + n_authkeys_file + 1;
+		filename = m_malloc(len);
+
+		/* check ~/.ssh */
+		snprintf(filename, len, "%s/%s", ses.authstate.pw_dir, user_authkeys_dir);
+		if (checkfileperm(filename) != DROPBEAR_SUCCESS) {
+			goto out;
+		}
+
+		/* now check ~/.ssh/authorized_keys */
+		snprintf(filename, len, "%s/%s/%s", ses.authstate.pw_dir,
+		         user_authkeys_dir, authkeys_file);
+		if (checkfileperm(filename) != DROPBEAR_SUCCESS) {
+			goto out;
+		}
 	}
 
 	/* file looks ok, return success */