From bd67b41f329702465d1d548ca2144b609e82927a Mon Sep 17 00:00:00 2001
From: bol-van <none@none.none>
Date: Mon, 3 Feb 2025 22:37:08 +0300
Subject: [PATCH] nfqws,tpws: check accessibility of list files after droproot

---
 docs/changes.txt |  1 +
 nfq/nfqws.c      | 27 +++++++++++++++++++++++++++
 tpws/tpws.c      | 25 ++++++++++++++++++++++++-
 3 files changed, 52 insertions(+), 1 deletion(-)

diff --git a/docs/changes.txt b/docs/changes.txt
index 748dc61..89833e7 100644
--- a/docs/changes.txt
+++ b/docs/changes.txt
@@ -456,3 +456,4 @@ nfqws,blockcheck: --dpi-desync-fake-tls-mod
 v70.1
 
 nfqws: --dpi-desync-fake-tls-mod=dupsid
+nfqws,tpws: test accessibility of list files after privs drop
diff --git a/nfq/nfqws.c b/nfq/nfqws.c
index 93cfffc..5b7b56c 100644
--- a/nfq/nfqws.c
+++ b/nfq/nfqws.c
@@ -120,6 +120,29 @@ static uint8_t processPacketData(uint32_t *mark, const char *ifout, uint8_t *dat
 }
 
 
+static bool test_list_files()
+{
+	struct hostlist_file *hfile;
+	struct ipset_file *ifile;
+
+	LIST_FOREACH(hfile, &params.hostlists, next)
+		if (!file_mod_time(hfile->filename))
+		{
+			DLOG_PERROR("file_mod_time");
+			DLOG_ERR("cannot access hostlist file '%s'\n",hfile->filename);
+			return false;
+		}
+	LIST_FOREACH(ifile, &params.ipsets, next)
+		if (!file_mod_time(ifile->filename))
+		{
+			DLOG_PERROR("file_mod_time");
+			DLOG_ERR("cannot access ipset file '%s'\n",ifile->filename);
+			return false;
+		}
+	return true;
+}
+
+
 #ifdef __linux__
 static int nfq_cb(struct nfq_q_handle *qh, struct nfgenmsg *nfmsg, struct nfq_data *nfa, void *cookie)
 {
@@ -260,6 +283,8 @@ static int nfq_main(void)
 	if (params.droproot && !droproot(params.uid, params.gid))
 		return 1;
 	print_id();
+	if (params.droproot && !test_list_files())
+		return 1;
 
 	pre_desync();
 
@@ -357,6 +382,8 @@ static int dvt_main(void)
 	if (params.droproot && !droproot(params.uid, params.gid))
 		goto exiterr;
 	print_id();
+	if (params.droproot && !test_list_files())
+		goto exiterr;
 
 	pre_desync();
 
diff --git a/tpws/tpws.c b/tpws/tpws.c
index c52a275..ddc7b98 100644
--- a/tpws/tpws.c
+++ b/tpws/tpws.c
@@ -116,6 +116,27 @@ static int8_t block_sigpipe(void)
 	return 0;
 }
 
+static bool test_list_files()
+{
+	struct hostlist_file *hfile;
+	struct ipset_file *ifile;
+
+	LIST_FOREACH(hfile, &params.hostlists, next)
+		if (!file_mod_time(hfile->filename))
+		{
+			DLOG_PERROR("file_mod_time");
+			DLOG_ERR("cannot access hostlist file '%s'\n",hfile->filename);
+			return false;
+		}
+	LIST_FOREACH(ifile, &params.ipsets, next)
+		if (!file_mod_time(ifile->filename))
+		{
+			DLOG_PERROR("file_mod_time");
+			DLOG_ERR("cannot access ipset file '%s'\n",ifile->filename);
+			return false;
+		}
+	return true;
+}
 
 static bool is_interface_online(const char *ifname)
 {
@@ -1918,10 +1939,12 @@ int main(int argc, char *argv[])
 
 	set_ulimit();
 	sec_harden();
-
 	if (params.droproot && !droproot(params.uid,params.gid))
 		goto exiterr;
 	print_id();
+	if (params.droproot && !test_list_files())
+		goto exiterr;
+
 	//splice() causes the process to receive the SIGPIPE-signal if one part (for
 	//example a socket) is closed during splice(). I would rather have splice()
 	//fail and return -1, so blocking SIGPIPE.