[lxc-devel] [lxc/master] cmd: fix usernet quota handling

[Piscolero on Github]

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From 042692e5ec224cd82d3be952b031073b91285964 Mon Sep 17 00:00:00 2001
From: Matthias Hardt <matthias.hardt at gmail.com>
Date: Wed, 18 Sep 2019 11:20:56 +0200
Subject: [PATCH] cmd: fix usernet quota handling

When comparing the usernet quota definitions with the usernic database
only the owner is evaluated and the nicname is ignored.

The following example leads to 'Quota reached' error although it shouldn't.

  lxc-usernet:
    user veth bridge1 1
    user veth bridge2 1

  container1:
    lxc.net.0.type = veth
    lxc.net.0.link = bridge1
    lxc.net.0.flags = up

  container2:
    lxc.net.0.type = veth
    lxc.net.0.link = bridge2
    lxc.net.0.flags = up

This fix counts only lines with matching user and nicname when checking
the quota.
---
 src/lxc/cmd/lxc_user_nic.c | 31 +++++++++++++++----------------
 1 file changed, 15 insertions(+), 16 deletions(-)

diff --git a/src/lxc/cmd/lxc_user_nic.c b/src/lxc/cmd/lxc_user_nic.c
index afa451deec..98b832866f 100644
--- a/src/lxc/cmd/lxc_user_nic.c
+++ b/src/lxc/cmd/lxc_user_nic.c
@@ -412,7 +412,8 @@ static char *get_eow(char *s, char *e)
 
 static char *find_line(char *buf_start, char *buf_end, char *name,
 		       char *net_type, char *net_link, char *net_dev,
-		       bool *owner, bool *found, bool *keep)
+		       bool *owner, bool *found_link, bool *found_dev,
+		       bool *keep)
 {
 	char *end_of_line, *end_of_word, *line;
 
@@ -420,7 +421,8 @@ static char *find_line(char *buf_start, char *buf_end, char *name,
 		size_t len;
 		char netdev_name[IFNAMSIZ];
 
-		*found = false;
+		*found_link = false;
+		*found_dev = false;
 		*keep = true;
 		*owner = false;
 
@@ -441,10 +443,8 @@ static char *find_line(char *buf_start, char *buf_end, char *name,
 		if (!end_of_word)
 			return NULL;
 
-		if (strncmp(buf_start, name, strlen(name)))
-			*found = false;
-		else
-			if (strlen(name) == (size_t)(end_of_word - buf_start))
+		if (!strncmp(buf_start, name, strlen(name)) &&
+			(strlen(name) == (size_t)(end_of_word - buf_start)))
 				*owner = true;
 
 		buf_start = end_of_word + 1;
@@ -457,9 +457,6 @@ static char *find_line(char *buf_start, char *buf_end, char *name,
 		if (!end_of_word)
 			return NULL;
 
-		if (strncmp(buf_start, net_type, strlen(net_type)))
-			*found = false;
-
 		buf_start = end_of_word + 1;
 		while ((buf_start < buf_end) && isblank(*buf_start))
 			buf_start++;
@@ -470,8 +467,9 @@ static char *find_line(char *buf_start, char *buf_end, char *name,
 		if (!end_of_word)
 			return NULL;
 
-		if (strncmp(buf_start, net_link, strlen(net_link)))
-			*found = false;
+		if (!strncmp(buf_start, net_link, strlen(net_link)) &&
+		    (strlen(net_link) == (size_t)(end_of_word - buf_start)))
+			*found_link = true;
 
 		buf_start = end_of_word + 1;
 		while ((buf_start < buf_end) && isblank(*buf_start))
@@ -493,7 +491,7 @@ static char *find_line(char *buf_start, char *buf_end, char *name,
 		*keep = lxc_nic_exists(netdev_name);
 
 		if (net_dev && !strcmp(netdev_name, net_dev))
-			*found = true;
+			*found_dev = true;
 
 		return line;
 
@@ -645,8 +643,8 @@ static bool cull_entries(int fd, char *name, char *net_type, char *net_link,
 	buf_start = buf;
 	buf_end = buf + sb.st_size;
 	while ((buf_start = find_line(buf_start, buf_end, name, net_type,
-				      net_link, net_dev, &(bool){true}, &found,
-				      &keep))) {
+				      net_link, net_dev, &(bool){true}, &(bool){true},
+				      &found, &keep))) {
 		struct entry_line *newe;
 
 		newe = realloc(entry_lines, sizeof(*entry_lines) * (n + 1));
@@ -693,12 +691,13 @@ static int count_entries(char *buf, off_t len, char *name, char *net_type, char
 {
 	int count = 0;
 	bool owner = false;
+	bool found = false;
 	char *buf_end;
 
 	buf_end = &buf[len];
 	while ((buf = find_line(buf, buf_end, name, net_type, net_link, NULL,
-				&owner, &(bool){true}, &(bool){true}))) {
-		if (owner)
+				&owner, &found, &(bool){true}, &(bool){true}))) {
+		if (owner && found)
 			count++;
 
 		buf = get_eol(buf, buf_end) + 1;