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#! /bin/sh /usr/share/dpatch/dpatch-run
# Description: fix arbitrary code execution via crafted hostname
# Author: Marius Tomaschewski
# Bug-Debian: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=621099
@DPATCH@
diff -urNad '--exclude=CVS' '--exclude=.svn' '--exclude=.git' '--exclude=.arch' '--exclude=.hg' '--exclude=_darcs' '--exclude=.bzr' dhcp3-3.1.3~/client/dhclient.c dhcp3-3.1.3/client/dhclient.c
--- dhcp3-3.1.3~/client/dhclient.c 2011-04-11 08:57:02.976060280 -0400
+++ dhcp3-3.1.3/client/dhclient.c 2011-04-11 08:57:16.536060277 -0400
@@ -77,6 +77,11 @@
int quiet=0;
int nowait=0;
+static int check_domain_name(const char *ptr, size_t len, int dots);
+static int check_domain_name_list(const char *ptr, size_t len, int dots);
+static int check_option_values(struct universe *universe, unsigned int opt,
+ const char *ptr, size_t len);
+
static void usage PROTO ((void));
int main (argc, argv, envp)
@@ -2524,13 +2529,23 @@
if (data.len) {
char name [256];
if (dhcp_option_ev_name (name, sizeof name,
- oc -> option)) {
- client_envadd (es -> client, es -> prefix,
- name, "%s",
- (pretty_print_option
- (oc -> option,
- data.data, data.len,
- 0, 0)));
+ oc->option)) {
+ const char *value;
+ value = pretty_print_option(oc->option,
+ data.data,
+ data.len, 0, 0);
+ size_t length = strlen(value);
+
+ if (check_option_values(oc->option->universe,
+ oc->option->code,
+ value, length) == 0) {
+ client_envadd(es->client, es->prefix,
+ name, "%s", value);
+ } else {
+ log_error("suspect value in %s "
+ "option - discarded",
+ name);
+ }
data_string_forget (&data, MDL);
}
}
@@ -2610,12 +2625,32 @@
data_string_forget (&data, MDL);
}
- if (lease -> filename)
- client_envadd (client,
- prefix, "filename", "%s", lease -> filename);
- if (lease -> server_name)
- client_envadd (client, prefix, "server_name",
- "%s", lease -> server_name);
+ if (lease->filename) {
+ if (check_option_values(NULL, DHO_ROOT_PATH,
+ lease->filename,
+ strlen(lease->filename)) == 0) {
+ client_envadd(client, prefix, "filename",
+ "%s", lease->filename);
+ } else {
+ log_error("suspect value in %s "
+ "option - discarded",
+ "filename");
+ }
+ }
+
+ if (lease->server_name) {
+ if (check_option_values(NULL, DHO_HOST_NAME,
+ lease->server_name,
+ strlen(lease->server_name)) == 0 ) {
+ client_envadd (client, prefix, "server_name",
+ "%s", lease->server_name);
+ } else {
+ log_error("suspect value in %s "
+ "option - discarded",
+ "server_name");
+ }
+ }
+
for (i = 0; i < lease -> options -> universe_count; i++) {
option_space_foreach ((struct packet *)0, (struct lease *)0,
@@ -3239,3 +3274,112 @@
data_string_forget (&ddns_dhcid, MDL);
return rcode;
}
+
+/*
+ * The following routines are used to check that certain
+ * strings are reasonable before we pass them to the scripts.
+ * This avoids some problems with scripts treating the strings
+ * as commands - see ticket 23722
+ * The domain checking code should be done as part of assembling
+ * the string but we are doing it here for now due to time
+ * constraints.
+ */
+
+static int check_domain_name(const char *ptr, size_t len, int dots)
+{
+ const char *p;
+
+ /* not empty or complete length not over 255 characters */
+ if ((len == 0) || (len > 256))
+ return(-1);
+
+ /* consists of [[:alnum:]-]+ labels separated by [.] */
+ /* a [_] is against RFC but seems to be "widely used"... */
+ for (p=ptr; (*p != 0) && (len-- > 0); p++) {
+ if ((*p == '-') || (*p == '_')) {
+ /* not allowed at begin or end of a label */
+ if (((p - ptr) == 0) || (len == 0) || (p[1] == '.'))
+ return(-1);
+ } else if (*p == '.') {
+ /* each label has to be 1-63 characters;
+ we allow [.] at the end ('foo.bar.') */
+ size_t d = p - ptr;
+ if ((d <= 0) || (d >= 64))
+ return(-1);
+ ptr = p + 1; /* jump to the next label */
+ if ((dots > 0) && (len > 0))
+ dots--;
+ } else if (isalnum((unsigned char)*p) == 0) {
+ /* also numbers at the begin are fine */
+ return(-1);
+ }
+ }
+ return(dots ? -1 : 0);
+}
+
+static int check_domain_name_list(const char *ptr, size_t len, int dots)
+{
+ const char *p;
+ int ret = -1; /* at least one needed */
+
+ if ((ptr == NULL) || (len == 0))
+ return(-1);
+
+ for (p=ptr; (*p != 0) && (len > 0); p++, len--) {
+ if (*p != ' ')
+ continue;
+ if (p > ptr) {
+ if (check_domain_name(ptr, p - ptr, dots) != 0)
+ return(-1);
+ ret = 0;
+ }
+ ptr = p + 1;
+ }
+ if (p > ptr)
+ return(check_domain_name(ptr, p - ptr, dots));
+ else
+ return(ret);
+}
+
+static int check_option_values(struct universe *universe,
+ unsigned int opt,
+ const char *ptr,
+ size_t len)
+{
+ if (ptr == NULL)
+ return(-1);
+
+ /* just reject options we want to protect, will be escaped anyway */
+ if ((universe == NULL) || (universe == &dhcp_universe)) {
+ switch(opt) {
+ case DHO_HOST_NAME:
+ case DHO_NIS_DOMAIN:
+ case DHO_NETBIOS_SCOPE:
+ return check_domain_name(ptr, len, 0);
+ break;
+ case DHO_DOMAIN_NAME: /* accept a list for compatibiliy */
+ return check_domain_name_list(ptr, len, 0);
+ break;
+ case DHO_ROOT_PATH:
+ if (len == 0)
+ return(-1);
+ for (; (*ptr != 0) && (len-- > 0); ptr++) {
+ if(!(isalnum((unsigned char)*ptr) ||
+ *ptr == '#' || *ptr == '%' ||
+ *ptr == '+' || *ptr == '-' ||
+ *ptr == '_' || *ptr == ':' ||
+ *ptr == '.' || *ptr == ',' ||
+ *ptr == '@' || *ptr == '~' ||
+ *ptr == '\\' || *ptr == '/' ||
+ *ptr == '[' || *ptr == ']' ||
+ *ptr == '=' || *ptr == ' '))
+ return(-1);
+ }
+ return(0);
+ break;
+ }
+ }
+
+ return(0);
+}
+
diff -urNad '--exclude=CVS' '--exclude=.svn' '--exclude=.git' '--exclude=.arch' '--exclude=.hg' '--exclude=_darcs' '--exclude=.bzr' dhcp3-3.1.3~/common/options.c dhcp3-3.1.3/common/options.c
--- dhcp3-3.1.3~/common/options.c 2011-04-11 08:57:02.966060280 -0400
+++ dhcp3-3.1.3/common/options.c 2011-04-11 08:57:16.536060277 -0400
@@ -2951,7 +2951,8 @@
count += 4;
}
} else if (**src == '"' || **src == '\'' || **src == '$' ||
- **src == '`' || **src == '\\') {
+ **src == '`' || **src == '\\' || **src == '|' ||
+ **src == '&') {
if (*dst + 2 > dend)
return -1;
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