From 19ed63e8ed3c5dece47c83949b61815f661c9036 Mon Sep 17 00:00:00 2001
From: Minhua Chen <chenminhua1@huawei.com>
Date: Tue, 21 Jan 2020 00:19:13 +0800
Subject: [PATCH] iproute2: change proc to ipnetnsproc which is private system
proc is mounted shared, if use this, it will cause the list size of mnt_share
become too large to loop, and will casue kernel softlockup.

so we need a private mounted proc which is /ipnetnsproc to avoid
the large list in kernel.

use /etc/iproute_private.conf to switch on or off this patch.
if file exist and file content equals use_ipnetnsproc=1 then
switch on, or else switch off.

Signed-off-by: Minhua Chen <chenminhua1@huawei.com>
---
 ip/ipnetns.c | 72 +++++++++++++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 64 insertions(+), 8 deletions(-)

diff --git a/ip/ipnetns.c b/ip/ipnetns.c
index fc58a04..fedc3db 100644
--- a/ip/ipnetns.c
+++ b/ip/ipnetns.c
@@ -25,6 +25,62 @@
 #include "namespace.h"
 #include "json_print.h"
 
+const char *conf_file = "/etc/iproute2/iproute_private.conf";
+static int conf_file_parsed = 0;
+static int should_use_ipnetnsproc = 0;
+
+static void parse_config()
+{
+	FILE *fp = NULL;
+	char buffer[256] = {0};
+	char *str = NULL;
+	char *p = NULL;
+
+	fp = fopen(conf_file, "r");
+	if(fp){
+		while (fgets(buffer, sizeof(buffer), fp)) {
+			str = buffer;
+			/* skip the space */
+			while (isspace(*str))
+				str++;
+			/* skip the comment line */
+			if (strncmp(str, "#", 1) == 0)
+				continue;
+			/* skip line feed */
+			if((p = strchr(str, '\n')) != NULL)
+				*p = '\0';
+			if (strstr(str, "use_ipnetnsproc") != NULL && (p = strstr(str, "=")) != NULL){
+				str = p + 1;
+				/* skip the space */
+				while (isspace(*str))
+					str++;
+				if (strcmp(str, "1") == 0){
+					should_use_ipnetnsproc = 1;
+				}
+				break;
+			}
+		}
+		fclose(fp);
+		fp = NULL;
+	}
+	conf_file_parsed = 1;
+}
+static int get_should_use_ipnetnsproc()
+{
+	if (!conf_file_parsed)
+		parse_config();
+	return should_use_ipnetnsproc;
+}
+
+static char* get_proc_string()
+{
+	if(get_should_use_ipnetnsproc()){
+		return "/ipnetnsproc";
+	} else {
+		return "/proc";
+	}
+} 
+
 static int usage(void)
 {
 	fprintf(stderr,
@@ -606,10 +663,9 @@ static int netns_pids(int argc, char **argv)
 			strerror(errno));
 		goto out;
 	}
-	dir = opendir("/proc/");
+	dir = opendir(get_proc_string());
 	if (!dir) {
-		fprintf(stderr, "Open of /proc failed: %s\n",
-			strerror(errno));
+		fprintf(stderr, "Open of %s failed: %s\n", get_proc_string(), strerror(errno));
 		goto out;
 	}
 	while ((entry = readdir(dir))) {
@@ -618,8 +674,7 @@ static int netns_pids(int argc, char **argv)
 
 		if (!is_pid(entry->d_name))
 			continue;
-		snprintf(pid_net_path, sizeof(pid_net_path), "/proc/%s/ns/net",
-			entry->d_name);
+		snprintf(pid_net_path, sizeof(pid_net_path), "/%s/%s/ns/net", get_proc_string(), entry->d_name);
 		if (stat(pid_net_path, &st) != 0)
 			continue;
 		if ((st.st_dev == netst.st_dev) &&
@@ -646,7 +701,7 @@ int netns_identify_pid(const char *pidstr, char *name, int len)
 
 	name[0] = '\0';
 
-	snprintf(net_path, sizeof(net_path), "/proc/%s/ns/net", pidstr);
+	snprintf(net_path, sizeof(net_path), "/%s/%s/ns/net", get_proc_string(), pidstr);
 	netns = open(net_path, O_RDONLY);
 	if (netns < 0) {
 		fprintf(stderr, "Cannot open network namespace: %s\n",
@@ -911,9 +965,9 @@ static int netns_add(int argc, char **argv, bool create)
 			goto out_delete;
 		}
 
-		strcpy(proc_path, "/proc/self/ns/net");
+		snprintf(proc_path, sizeof(proc_path), "/%s/self/ns/net", get_proc_string());
 	} else {
-		snprintf(proc_path, sizeof(proc_path), "/proc/%d/ns/net", pid);
+		snprintf(proc_path, sizeof(proc_path), "/%s/%d/ns/net", get_proc_string(), pid);
 	}
 
 	/* Bind the netns last so I can watch for it */
-- 
1.8.3.1