diff options
| -rw-r--r-- | include/net/netlink.h | 18 | ||||
| -rw-r--r-- | lib/nlattr.c | 4 |
2 files changed, 22 insertions, 0 deletions
diff --git a/include/net/netlink.h b/include/net/netlink.h index e4dd874412bf..679f649748d4 100644 --- a/include/net/netlink.h +++ b/include/net/netlink.h @@ -299,6 +299,24 @@ struct nla_policy { }; int (*validate)(const struct nlattr *attr, struct netlink_ext_ack *extack); + /* This entry is special, and used for the attribute at index 0 + * only, and specifies special data about the policy, namely it + * specifies the "boundary type" where strict length validation + * starts for any attribute types >= this value, also, strict + * nesting validation starts here. + * + * Additionally, it means that NLA_UNSPEC is actually NLA_REJECT + * for any types >= this, so need to use NLA_MIN_LEN to get the + * previous pure { .len = xyz } behaviour. The advantage of this + * is that types not specified in the policy will be rejected. + * + * For completely new families it should be set to 1 so that the + * validation is enforced for all attributes. For existing ones + * it should be set at least when new attributes are added to + * the enum used by the policy, and be set to the new value that + * was added to enforce strict validation from thereon. + */ + u16 strict_start_type; }; }; diff --git a/lib/nlattr.c b/lib/nlattr.c index af0f8b0309c6..29f6336e2422 100644 --- a/lib/nlattr.c +++ b/lib/nlattr.c @@ -158,10 +158,14 @@ static int validate_nla(const struct nlattr *nla, int maxtype, const struct nla_policy *policy, unsigned int validate, struct netlink_ext_ack *extack) { + u16 strict_start_type = policy[0].strict_start_type; const struct nla_policy *pt; int minlen = 0, attrlen = nla_len(nla), type = nla_type(nla); int err = -ERANGE; + if (strict_start_type && type >= strict_start_type) + validate |= NL_VALIDATE_STRICT; + if (type <= 0 || type > maxtype) return 0; |