summaryrefslogtreecommitdiff
path: root/package/busybox/patches/006-upstream_CVE-2011-2716_fixes.patch
blob: 532fcee0fb51f9a926f06c34fa1aeb96715244c1 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
--- a/networking/udhcp/common.c
+++ b/networking/udhcp/common.c
@@ -29,16 +29,16 @@ const struct dhcp_optflag dhcp_optflags[
 //	{ OPTION_IP | OPTION_LIST                 , 0x07 }, /* DHCP_LOG_SERVER    */
 //	{ OPTION_IP | OPTION_LIST                 , 0x08 }, /* DHCP_COOKIE_SERVER */
 	{ OPTION_IP | OPTION_LIST                 , 0x09 }, /* DHCP_LPR_SERVER    */
-	{ OPTION_STRING               | OPTION_REQ, 0x0c }, /* DHCP_HOST_NAME     */
+	{ OPTION_STRING_HOST          | OPTION_REQ, 0x0c }, /* DHCP_HOST_NAME     */
 	{ OPTION_U16                              , 0x0d }, /* DHCP_BOOT_SIZE     */
-	{ OPTION_STRING               | OPTION_REQ, 0x0f }, /* DHCP_DOMAIN_NAME   */
+	{ OPTION_STRING_HOST          | OPTION_REQ, 0x0f }, /* DHCP_DOMAIN_NAME   */
 	{ OPTION_IP                               , 0x10 }, /* DHCP_SWAP_SERVER   */
 	{ OPTION_STRING                           , 0x11 }, /* DHCP_ROOT_PATH     */
 	{ OPTION_U8                               , 0x17 }, /* DHCP_IP_TTL        */
 	{ OPTION_U16                              , 0x1a }, /* DHCP_MTU           */
 	{ OPTION_IP                   | OPTION_REQ, 0x1c }, /* DHCP_BROADCAST     */
 	{ OPTION_IP_PAIR | OPTION_LIST            , 0x21 }, /* DHCP_ROUTES        */
-	{ OPTION_STRING                           , 0x28 }, /* DHCP_NIS_DOMAIN    */
+	{ OPTION_STRING_HOST                      , 0x28 }, /* DHCP_NIS_DOMAIN    */
 	{ OPTION_IP | OPTION_LIST                 , 0x29 }, /* DHCP_NIS_SERVER    */
 	{ OPTION_IP | OPTION_LIST     | OPTION_REQ, 0x2a }, /* DHCP_NTP_SERVER    */
 	{ OPTION_IP | OPTION_LIST                 , 0x2c }, /* DHCP_WINS_SERVER   */
@@ -46,7 +46,7 @@ const struct dhcp_optflag dhcp_optflags[
 	{ OPTION_IP                               , 0x36 }, /* DHCP_SERVER_ID     */
 	{ OPTION_STRING                           , 0x38 }, /* DHCP_ERR_MESSAGE   */
 //TODO: must be combined with 'sname' and 'file' handling:
-	{ OPTION_STRING                           , 0x42 }, /* DHCP_TFTP_SERVER_NAME */
+	{ OPTION_STRING_HOST                      , 0x42 }, /* DHCP_TFTP_SERVER_NAME */
 	{ OPTION_STRING                           , 0x43 }, /* DHCP_BOOT_FILE     */
 //TODO: not a string, but a set of LASCII strings:
 //	{ OPTION_STRING                           , 0x4D }, /* DHCP_USER_CLASS    */
@@ -143,6 +143,7 @@ const uint8_t dhcp_option_lengths[] ALIG
 	[OPTION_IP_PAIR] = 8,
 //	[OPTION_BOOLEAN] = 1,
 	[OPTION_STRING] =  1,  /* ignored by udhcp_str2optset */
+	[OPTION_STRING_HOST] = 1,  /* ignored by udhcp_str2optset */
 #if ENABLE_FEATURE_UDHCP_RFC3397
 	[OPTION_DNS_STRING] = 1,  /* ignored by both udhcp_str2optset and xmalloc_optname_optval */
 	[OPTION_SIP_SERVERS] = 1,
@@ -411,7 +412,9 @@ static NOINLINE void attach_option(
 			/* actually 255 is ok too, but adding a space can overlow it */
 
 			existing->data = xrealloc(existing->data, OPT_DATA + 1 + old_len + length);
-			if ((optflag->flags & OPTION_TYPE_MASK) == OPTION_STRING) {
+			if ((optflag->flags & OPTION_TYPE_MASK) == OPTION_STRING
+			 || (optflag->flags & OPTION_TYPE_MASK) == OPTION_STRING_HOST
+			) {
 				/* add space separator between STRING options in a list */
 				existing->data[OPT_DATA + old_len] = ' ';
 				old_len++;
@@ -475,6 +478,7 @@ int FAST_FUNC udhcp_str2optset(const cha
 				retval = udhcp_str2nip(val, buffer + 4);
 			break;
 		case OPTION_STRING:
+		case OPTION_STRING_HOST:
 #if ENABLE_FEATURE_UDHCP_RFC3397
 		case OPTION_DNS_STRING:
 #endif
--- a/networking/udhcp/common.h
+++ b/networking/udhcp/common.h
@@ -80,6 +80,9 @@ enum {
 	OPTION_IP = 1,
 	OPTION_IP_PAIR,
 	OPTION_STRING,
+	/* Opts of STRING_HOST type will be sanitized before they are passed
+	 * to udhcpc script's environment: */
+	OPTION_STRING_HOST,
 //	OPTION_BOOLEAN,
 	OPTION_U8,
 	OPTION_U16,
--- a/networking/udhcp/dhcpc.c
+++ b/networking/udhcp/dhcpc.c
@@ -101,6 +101,7 @@ static const uint8_t len_of_option_as_st
 	[OPTION_IP_PAIR         ] = sizeof("255.255.255.255 ") * 2,
 	[OPTION_STATIC_ROUTES   ] = sizeof("255.255.255.255/32 255.255.255.255 "),
 	[OPTION_STRING          ] = 1,
+	[OPTION_STRING_HOST     ] = 1,
 #if ENABLE_FEATURE_UDHCP_RFC3397
 	[OPTION_DNS_STRING      ] = 1, /* unused */
 	/* Hmmm, this severely overestimates size if SIP_SERVERS option
@@ -135,6 +136,63 @@ static int mton(uint32_t mask)
 	return i;
 }
 
+/* Check if a given label represents a valid DNS label
+ * Return pointer to the first character after the label upon success,
+ * NULL otherwise.
+ * See RFC1035, 2.3.1
+ */
+/* We don't need to be particularly anal. For example, allowing _, hyphen
+ * at the end, or leading and trailing dots would be ok, since it
+ * can't be used for attacks. (Leading hyphen can be, if someone uses
+ * cmd "$hostname"
+ * in the script: then hostname may be treated as an option)
+ */
+static const char *valid_domain_label(const char *label)
+{
+	unsigned char ch;
+	unsigned pos = 0;
+
+	for (;;) {
+		ch = *label;
+		if ((ch|0x20) < 'a' || (ch|0x20) > 'z') {
+			if (pos == 0) {
+				/* label must begin with letter */
+				return NULL;
+			}
+			if (ch < '0' || ch > '9') {
+				if (ch == '\0' || ch == '.')
+					return label;
+				/* DNS allows only '-', but we are more permissive */
+				if (ch != '-' && ch != '_')
+					return NULL;
+			}
+		}
+		label++;
+		pos++;
+		//Do we want this?
+		//if (pos > 63) /* NS_MAXLABEL; labels must be 63 chars or less */
+		//	return NULL;
+	}
+}
+
+/* Check if a given name represents a valid DNS name */
+/* See RFC1035, 2.3.1 */
+static int good_hostname(const char *name)
+{
+	//const char *start = name;
+
+	for (;;) {
+		name = valid_domain_label(name);
+		if (!name)
+			return 0;
+		if (!name[0])
+			return 1;
+			//Do we want this?
+			//return ((name - start) < 1025); /* NS_MAXDNAME */
+		name++;
+	}
+}
+
 /* Create "opt_name=opt_value" string */
 static NOINLINE char *xmalloc_optname_optval(uint8_t *option, const struct dhcp_optflag *optflag, const char *opt_name)
 {
@@ -185,8 +243,11 @@ static NOINLINE char *xmalloc_optname_op
 			break;
 		}
 		case OPTION_STRING:
+		case OPTION_STRING_HOST:
 			memcpy(dest, option, len);
 			dest[len] = '\0';
+			if (type == OPTION_STRING_HOST && !good_hostname(dest))
+				safe_strncpy(dest, "bad", len);
 			return ret;	 /* Short circuit this case */
 		case OPTION_STATIC_ROUTES: {
 			/* Option binary format:
@@ -314,6 +375,7 @@ static char **fill_envp(struct dhcp_pack
 	/* +1 element for each option, +2 for subnet option: */
 	if (packet) {
 		/* note: do not search for "pad" (0) and "end" (255) options */
+//TODO: change logic to scan packet _once_
 		for (i = 1; i < 255; i++) {
 			temp = udhcp_get_option(packet, i);
 			if (temp) {