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netlink: add validation function to policy 

Add the ability to have an arbitrary validation function attached
to a netlink policy that doesn't already use the validation_data
pointer in another way.

This can be useful to validate for example the content of a binary
attribute, like in nl80211 the "(information) elements", which must
be valid streams of "u8 type, u8 length, u8 value[length]".

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
hifive-unleashed-5.1
Johannes Berg 2018-09-27 11:28:36 +02:00 committed by David S. Miller
parent 3e48be05f3
commit 33188bd643
2 changed files with 30 additions and 1 deletions
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24
include/net/netlink.h
View File

@ -193,13 +193,14 @@ enum nla_policy_validation {
NLA_VALIDATE_RANGE,
NLA_VALIDATE_MIN,
NLA_VALIDATE_MAX,
NLA_VALIDATE_FUNCTION,
};
/**
* struct nla_policy - attribute validation policy
* @type: Type of attribute or NLA_UNSPEC
* @validation_type: type of attribute validation done in addition to
* type-specific validation (e.g. range), see
* type-specific validation (e.g. range, function call), see
* &enum nla_policy_validation
* @len: Type specific length of payload
*
@ -269,6 +270,13 @@ enum nla_policy_validation {
* of s16 - do that as usual in the code instead.
* All other Unused - but note that it's a union
*
* Meaning of `validate' field, use via NLA_POLICY_VALIDATE_FN:
* NLA_BINARY Validation function called for the attribute,
* not compatible with use of the validation_data
* as in NLA_BITFIELD32, NLA_REJECT, NLA_NESTED and
* NLA_NESTED_ARRAY.
* All other Unused - but note that it's a union
*
* Example:
* static const struct nla_policy my_policy[ATTR_MAX+1] = {
* [ATTR_FOO] = { .type = NLA_U16 },
@ -286,6 +294,8 @@ struct nla_policy {
struct {
s16 min, max;
};
int (*validate)(const struct nlattr *attr,
struct netlink_ext_ack *extack);
};
};
@ -307,6 +317,11 @@ struct nla_policy {
tp == NLA_S16 || tp == NLA_U16 || \
tp == NLA_S32 || tp == NLA_U32 || \
tp == NLA_S64 || tp == NLA_U64) + tp)
#define NLA_ENSURE_NO_VALIDATION_PTR(tp) \
(__NLA_ENSURE(tp != NLA_BITFIELD32 && \
tp != NLA_REJECT && \
tp != NLA_NESTED && \
tp != NLA_NESTED_ARRAY) + tp)
#define NLA_POLICY_RANGE(tp, _min, _max) { \
.type = NLA_ENSURE_INT_TYPE(tp), \
@ -327,6 +342,13 @@ struct nla_policy {
.max = _max, \
}
#define NLA_POLICY_VALIDATE_FN(tp, fn, ...) { \
.type = NLA_ENSURE_NO_VALIDATION_PTR(tp), \
.validation_type = NLA_VALIDATE_FUNCTION, \
.validate = fn, \
.len = __VA_ARGS__ + 0, \
}
/**
* struct nl_info - netlink source information
* @nlh: Netlink message header of original request

7
lib/nlattr.c
View File

@ -300,6 +300,13 @@ static int validate_nla(const struct nlattr *nla, int maxtype,
if (err)
return err;
break;
case NLA_VALIDATE_FUNCTION:
if (pt->validate) {
err = pt->validate(nla, extack);
if (err)
return err;
}
break;
}
return 0;