# HG changeset patch
# User Roy Marples <roy@marples.name>
# Date 1590328181 -3600
# Node ID 95976721c27ddd059aee4979171c291d41c37586
# Parent  9ea5c678d8a6266b38f60b9a817fe8c1f68058e1
privsep: Avoid the /proc/../ escape

diff -r 9ea5c678d8a6 -r 95976721c27d src/privsep-root.c
--- a/src/privsep-root.c	Sun May 24 14:32:15 2020 +0100
+++ b/src/privsep-root.c	Sun May 24 14:49:41 2020 +0100
@@ -288,6 +288,11 @@
 ps_root_validpath(const struct dhcpcd_ctx *ctx, uint16_t cmd, const char *path)
 {
 
+	/* Avoid a previous directory attack to avoid /proc/../
+	 * dhcpcd should never use a path with double dots. */
+	if (strstr(path, "..") != NULL)
+		return false;
+
 	if (cmd == PS_READFILE) {
 		if (strcmp(ctx->cffile, path) == 0)
 			return true;