From 4b6cc7284ddc9a54910f111085ebf0143ef3f5bd Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Thu, 3 Nov 2011 00:10:05 +0000 Subject: [PATCH] netlink: clarify attribute length check documentation The documentation for how the length of attributes is checked is wrong ("Exact length" isn't true, the policy checks are for "minimum length") and a bit misleading. Make it more complete and explain what really happens. Cc: Thomas Graf Signed-off-by: Johannes Berg Signed-off-by: David S. Miller --- include/net/netlink.h | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/include/net/netlink.h b/include/net/netlink.h index 98c185441bee..cb1f3504687f 100644 --- a/include/net/netlink.h +++ b/include/net/netlink.h @@ -192,8 +192,15 @@ enum { * NLA_NUL_STRING Maximum length of string (excluding NUL) * NLA_FLAG Unused * NLA_BINARY Maximum length of attribute payload - * NLA_NESTED_COMPAT Exact length of structure payload - * All other Exact 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_COMPAT Minimum length of structure payload + * NLA_U8, NLA_U16, + * NLA_U32, NLA_U64, + * NLA_MSECS Leaving the length field zero will verify the + * given type fits, using it verifies minimum length + * just like "All other" + * All other Minimum length of attribute payload * * Example: * static const struct nla_policy my_policy[ATTR_MAX+1] = { -- 2.30.2