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Date: Thu, 15 Oct 2015 18:39:09 +0200
From: Jiri Benc <jbenc@...hat.com>
To: netdev@...r.kernel.org
Cc: Thomas Graf <tgraf@...g.ch>
Subject: [RFC PATCH net-next 4/9] netlink: strict attribute validation
Enhance the attribute validation functions to support strict attribute
checking. Keep the semantics of the current nla_validate and nlmsg_validate
functions.
Signed-off-by: Jiri Benc <jbenc@...hat.com>
---
include/net/netlink.h | 67 ++++++++++++++++++++++++++++++++++++++++++++-------
lib/nlattr.c | 24 +++++++++++-------
2 files changed, 73 insertions(+), 18 deletions(-)
diff --git a/include/net/netlink.h b/include/net/netlink.h
index dcca6853913d..233a68e1c955 100644
--- a/include/net/netlink.h
+++ b/include/net/netlink.h
@@ -233,8 +233,8 @@ int netlink_rcv_skb(struct sk_buff *skb, bool strict_supported,
int nlmsg_notify(struct sock *sk, struct sk_buff *skb, u32 portid,
unsigned int group, int report, gfp_t flags);
-int nla_validate(const struct nlattr *head, int len, int maxtype,
- const struct nla_policy *policy);
+int nla_strict_validate(const struct nlattr *head, int len, int maxtype,
+ bool strict, const struct nla_policy *policy);
int nla_strict_parse(struct nlattr **tb, int maxtype, bool strict,
const struct nlattr *head, int len,
const struct nla_policy *policy);
@@ -413,6 +413,26 @@ static inline struct nlattr *nlmsg_find_attr(const struct nlmsghdr *nlh,
}
/**
+ * nlmsg_strict_validate - validate a netlink message including attributes
+ * @nlh: netlinket message header
+ * @hdrlen: length of familiy specific header
+ * @maxtype: maximum attribute type to be expected
+ * @strict: whether to perform strict checking
+ * @policy: validation policy
+ */
+static inline int nlmsg_strict_validate(const struct nlmsghdr *nlh,
+ int hdrlen, int maxtype, bool strict,
+ const struct nla_policy *policy)
+{
+ if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
+ return -EINVAL;
+
+ return nla_strict_validate(nlmsg_attrdata(nlh, hdrlen),
+ nlmsg_attrlen(nlh, hdrlen), maxtype,
+ strict, policy);
+}
+
+/**
* nlmsg_validate - validate a netlink message including attributes
* @nlh: netlinket message header
* @hdrlen: length of familiy specific header
@@ -423,11 +443,7 @@ static inline int nlmsg_validate(const struct nlmsghdr *nlh,
int hdrlen, int maxtype,
const struct nla_policy *policy)
{
- if (nlh->nlmsg_len < nlmsg_msg_size(hdrlen))
- return -EINVAL;
-
- return nla_validate(nlmsg_attrdata(nlh, hdrlen),
- nlmsg_attrlen(nlh, hdrlen), maxtype, policy);
+ return nlmsg_strict_validate(nlh, hdrlen, maxtype, false, policy);
}
/**
@@ -1270,17 +1286,50 @@ static inline void nla_nest_cancel(struct sk_buff *skb, struct nlattr *start)
}
/**
- * nla_validate_nested - Validate a stream of nested attributes
+ * nla_validate - Validate a stream of attributes
+ * @head: head of attribute stream
+ * @len: length of attribute stream
+ * @maxtype: maximum attribute type to be expected
+ * @policy: validation policy
+ *
+ * See nla_strict_validate(). Strict checking is not performed.
+ */
+static inline int nla_validate(const struct nlattr *head, int len,
+ int maxtype, const struct nla_policy *policy)
+{
+ return nla_strict_validate(head, len, maxtype, false, policy);
+}
+
+/**
+ * nla_strict_validate_nested - Validate a stream of nested attributes
* @start: container attribute
* @maxtype: maximum attribute type to be expected
+ * @strict: whether to perform strict checking
* @policy: validation policy
*
* Validates all attributes in the nested attribute stream against the
* specified policy. Attributes with a type exceeding maxtype will be
- * ignored. See documenation of struct nla_policy for more details.
+ * ignored, unless strict is set. See documenation of struct nla_policy for
+ * more details.
*
* Returns 0 on success or a negative error code.
*/
+static inline int nla_strict_validate_nested(const struct nlattr *start,
+ int maxtype, bool strict,
+ const struct nla_policy *policy)
+{
+ return nla_strict_validate(nla_data(start), nla_len(start), maxtype,
+ strict, policy);
+}
+
+/**
+ * nla_validate_nested - Validate a stream of nested attributes
+ * @start: container attribute
+ * @maxtype: maximum attribute type to be expected
+ * @policy: validation policy
+ *
+ * See nla_strict_validate_nested(). Strict checking is not performed.
+ */
static inline int nla_validate_nested(const struct nlattr *start, int maxtype,
const struct nla_policy *policy)
{
diff --git a/lib/nlattr.c b/lib/nlattr.c
index 2b36388eb3a9..86bc0662caee 100644
--- a/lib/nlattr.c
+++ b/lib/nlattr.c
@@ -27,14 +27,17 @@ static const u16 nla_attr_minlen[NLA_TYPE_MAX+1] = {
[NLA_S64] = sizeof(s64),
};
-static int validate_nla(const struct nlattr *nla, int maxtype,
+static int validate_nla(const struct nlattr *nla, int maxtype, bool strict,
const struct nla_policy *policy)
{
const struct nla_policy *pt;
int minlen = 0, attrlen = nla_len(nla), type = nla_type(nla);
- if (type <= 0 || type > maxtype)
+ if (type <= 0 || type > maxtype) {
+ if (strict)
+ return -EINVAL;
return 0;
+ }
pt = &policy[type];
@@ -107,33 +110,35 @@ static int validate_nla(const struct nlattr *nla, int maxtype,
}
/**
- * nla_validate - Validate a stream of attributes
+ * nla_strict_validate - Validate a stream of attributes
* @head: head of attribute stream
* @len: length of attribute stream
* @maxtype: maximum attribute type to be expected
+ * @strict: whether to perform strict checking
* @policy: validation policy
*
* Validates all attributes in the specified attribute stream against the
* specified policy. Attributes with a type exceeding maxtype will be
- * ignored. See documenation of struct nla_policy for more details.
+ * ignored, unless strict is set. See documenation of struct nla_policy for
+ * more details.
*
* Returns 0 on success or a negative error code.
*/
-int nla_validate(const struct nlattr *head, int len, int maxtype,
- const struct nla_policy *policy)
+int nla_strict_validate(const struct nlattr *head, int len, int maxtype,
+ bool strict, const struct nla_policy *policy)
{
const struct nlattr *nla;
int rem, err;
nla_for_each_attr(nla, head, len, rem) {
- err = validate_nla(nla, maxtype, policy);
+ err = validate_nla(nla, maxtype, strict, policy);
if (err < 0)
return err;
}
return 0;
}
-EXPORT_SYMBOL(nla_validate);
+EXPORT_SYMBOL(nla_strict_validate);
/**
* nla_policy_len - Determin the max. length of a policy
@@ -193,7 +198,8 @@ int nla_strict_parse(struct nlattr **tb, int maxtype, bool strict,
if (type > 0 && type <= maxtype) {
if (policy) {
- err = validate_nla(nla, maxtype, policy);
+ err = validate_nla(nla, maxtype, strict,
+ policy);
if (err < 0)
return err;
}
--
1.8.3.1
--
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