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authorLinus Torvalds <torvalds@linux-foundation.org>2011-03-03 15:48:01 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2011-03-03 15:48:01 -0800
commitb65a0e0c84cf489bfa00d6aa6c48abc5a237100f (patch)
tree3ed9d7b094e003a7b0d98234cb5b490d671bf3a9
parent4438a02fc4956f5f61918095708f183f5c63a9d3 (diff)
parent1362fa078dae16776cd439791c6605b224ea6171 (diff)
downloadlinux-stericsson-b65a0e0c84cf489bfa00d6aa6c48abc5a237100f.tar.gz
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/security-testing-2.6
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/security-testing-2.6: DNS: Fix a NULL pointer deref when trying to read an error key [CVE-2011-1076]
-rw-r--r--Documentation/networking/dns_resolver.txt9
-rw-r--r--net/dns_resolver/dns_key.c20
2 files changed, 25 insertions, 4 deletions
diff --git a/Documentation/networking/dns_resolver.txt b/Documentation/networking/dns_resolver.txt
index aefd1e681804..04ca06325b08 100644
--- a/Documentation/networking/dns_resolver.txt
+++ b/Documentation/networking/dns_resolver.txt
@@ -61,7 +61,6 @@ before the more general line given above as the first match is the one taken.
create dns_resolver foo:* * /usr/sbin/dns.foo %k
-
=====
USAGE
=====
@@ -104,6 +103,14 @@ implemented in the module can be called after doing:
returned also.
+===============================
+READING DNS KEYS FROM USERSPACE
+===============================
+
+Keys of dns_resolver type can be read from userspace using keyctl_read() or
+"keyctl read/print/pipe".
+
+
=========
MECHANISM
=========
diff --git a/net/dns_resolver/dns_key.c b/net/dns_resolver/dns_key.c
index 739435a6af39..cfa7a5e1c5c9 100644
--- a/net/dns_resolver/dns_key.c
+++ b/net/dns_resolver/dns_key.c
@@ -67,8 +67,9 @@ dns_resolver_instantiate(struct key *key, const void *_data, size_t datalen)
size_t result_len = 0;
const char *data = _data, *end, *opt;
- kenter("%%%d,%s,'%s',%zu",
- key->serial, key->description, data, datalen);
+ kenter("%%%d,%s,'%*.*s',%zu",
+ key->serial, key->description,
+ (int)datalen, (int)datalen, data, datalen);
if (datalen <= 1 || !data || data[datalen - 1] != '\0')
return -EINVAL;
@@ -217,6 +218,19 @@ static void dns_resolver_describe(const struct key *key, struct seq_file *m)
seq_printf(m, ": %u", key->datalen);
}
+/*
+ * read the DNS data
+ * - the key's semaphore is read-locked
+ */
+static long dns_resolver_read(const struct key *key,
+ char __user *buffer, size_t buflen)
+{
+ if (key->type_data.x[0])
+ return key->type_data.x[0];
+
+ return user_read(key, buffer, buflen);
+}
+
struct key_type key_type_dns_resolver = {
.name = "dns_resolver",
.instantiate = dns_resolver_instantiate,
@@ -224,7 +238,7 @@ struct key_type key_type_dns_resolver = {
.revoke = user_revoke,
.destroy = user_destroy,
.describe = dns_resolver_describe,
- .read = user_read,
+ .read = dns_resolver_read,
};
static int __init init_dns_resolver(void)