diff --git a/include/net/netlink.h b/include/net/netlink.h index 0d698215d4d9..91907852da1c 100644 --- a/include/net/netlink.h +++ b/include/net/netlink.h @@ -200,8 +200,10 @@ enum { * NLA_NUL_STRING Maximum length of string (excluding NUL) * NLA_FLAG Unused * NLA_BINARY Maximum length of attribute payload - * NLA_NESTED Don't use `len' field -- length verification is - * done by checking len of nested header (or empty) + * NLA_NESTED Length verification is done by checking len of + * nested header (or empty); len field is used if + * validation_data is also used, for the max attr + * number in the nested policy. * NLA_U8, NLA_U16, * NLA_U32, NLA_U64, * NLA_S8, NLA_S16, @@ -224,6 +226,10 @@ enum { * NLA_REJECT This attribute is always rejected and validation data * may point to a string to report as the error instead * of the generic one in extended ACK. + * NLA_NESTED Points to a nested policy to validate, must also set + * `len' to the max attribute number. + * Note that nla_parse() will validate, but of course not + * parse, the nested sub-policies. * All other Unused * * Example: @@ -247,6 +253,9 @@ struct nla_policy { #define NLA_POLICY_ETH_ADDR NLA_POLICY_EXACT_LEN(ETH_ALEN) #define NLA_POLICY_ETH_ADDR_COMPAT NLA_POLICY_EXACT_LEN_WARN(ETH_ALEN) +#define NLA_POLICY_NESTED(maxattr, policy) \ + { .type = NLA_NESTED, .validation_data = policy, .len = maxattr } + /** * struct nl_info - netlink source information * @nlh: Netlink message header of original request diff --git a/lib/nlattr.c b/lib/nlattr.c index 6e03d650bec4..04750f88477c 100644 --- a/lib/nlattr.c +++ b/lib/nlattr.c @@ -155,6 +155,20 @@ static int validate_nla(const struct nlattr *nla, int maxtype, */ if (attrlen == 0) break; + if (attrlen < NLA_HDRLEN) + goto out_err; + if (pt->validation_data) { + err = nla_validate(nla_data(nla), nla_len(nla), pt->len, + pt->validation_data, extack); + if (err < 0) { + /* + * return directly to preserve the inner + * error message/attribute pointer + */ + return err; + } + } + break; default: if (pt->len) minlen = pt->len;