redonkable
/
alistair23-linux
1
0
Fork 0
Code Releases Activity

netlink: allow NLA_NESTED to specify nested policy to validate 

Now that we have a validation_data pointer, and the len field in
the policy is unused for NLA_NESTED, we can allow using them both
to have nested validation. This can be nice in code, although we
still have to use nla_parse_nested() or similar which would also
take a policy; however, it also serves as documentation in the
policy without requiring a look at the code.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
hifive-unleashed-5.1
Johannes Berg 2018-09-26 11:15:33 +02:00 committed by David S. Miller
parent c29f1845b2
commit 9a659a35ba
2 changed files with 25 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
include/net/netlink.h
View File

@ -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

14
lib/nlattr.c
View File

@ -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;