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// SPDX-License-Identifier: GPL-2.0
/*
* NETLINK Policy advertisement to userspace
*
* Authors: Johannes Berg <johannes@sipsolutions.net>
*
* Copyright 2019 Intel Corporation
*/
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/types.h>
#include <net/netlink.h>
#define INITIAL_POLICIES_ALLOC 10
struct netlink_policy_dump_state {
unsigned int policy_idx;
unsigned int attr_idx;
unsigned int n_alloc;
struct {
const struct nla_policy *policy;
unsigned int maxtype;
} policies[];
};
static int add_policy(struct netlink_policy_dump_state **statep,
const struct nla_policy *policy,
unsigned int maxtype)
{
struct netlink_policy_dump_state *state = *statep;
unsigned int n_alloc, i;
if (!policy || !maxtype)
return 0;
for (i = 0; i < state->n_alloc; i++) {
if (state->policies[i].policy == policy &&
state->policies[i].maxtype == maxtype)
return 0;
if (!state->policies[i].policy) {
state->policies[i].policy = policy;
state->policies[i].maxtype = maxtype;
return 0;
}
}
n_alloc = state->n_alloc + INITIAL_POLICIES_ALLOC;
state = krealloc(state, struct_size(state, policies, n_alloc),
GFP_KERNEL);
if (!state)
return -ENOMEM;
memset(&state->policies[state->n_alloc], 0,
flex_array_size(state, policies, n_alloc - state->n_alloc));
state->policies[state->n_alloc].policy = policy;
state->policies[state->n_alloc].maxtype = maxtype;
state->n_alloc = n_alloc;
*statep = state;
return 0;
}
static unsigned int get_policy_idx(struct netlink_policy_dump_state *state,
const struct nla_policy *policy,
unsigned int maxtype)
{
unsigned int i;
for (i = 0; i < state->n_alloc; i++) {
if (state->policies[i].policy == policy &&
state->policies[i].maxtype == maxtype)
return i;
}
WARN_ON_ONCE(1);
return -1;
}
int netlink_policy_dump_start(const struct nla_policy *policy,
unsigned int maxtype,
struct netlink_policy_dump_state **statep)
{
struct netlink_policy_dump_state *state;
unsigned int policy_idx;
int err;
if (*statep)
return 0;
/*
* walk the policies and nested ones first, and build
* a linear list of them.
*/
state = kzalloc(struct_size(state, policies, INITIAL_POLICIES_ALLOC),
GFP_KERNEL);
if (!state)
return -ENOMEM;
state->n_alloc = INITIAL_POLICIES_ALLOC;
err = add_policy(&state, policy, maxtype);
if (err)
return err;
for (policy_idx = 0;
policy_idx < state->n_alloc && state->policies[policy_idx].policy;
policy_idx++) {
const struct nla_policy *policy;
unsigned int type;
policy = state->policies[policy_idx].policy;
for (type = 0;
type <= state->policies[policy_idx].maxtype;
type++) {
switch (policy[type].type) {
case NLA_NESTED:
case NLA_NESTED_ARRAY:
err = add_policy(&state,
policy[type].nested_policy,
policy[type].len);
if (err)
return err;
break;
default:
break;
}
}
}
*statep = state;
return 0;
}
static bool
netlink_policy_dump_finished(struct netlink_policy_dump_state *state)
{
return state->policy_idx >= state->n_alloc ||
!state->policies[state->policy_idx].policy;
}
bool netlink_policy_dump_loop(struct netlink_policy_dump_state *state)
{
return !netlink_policy_dump_finished(state);
}
int netlink_policy_dump_write(struct sk_buff *skb,
struct netlink_policy_dump_state *state)
{
const struct nla_policy *pt;
struct nlattr *policy, *attr;
enum netlink_attribute_type type;
bool again;
send_attribute:
again = false;
pt = &state->policies[state->policy_idx].policy[state->attr_idx];
policy = nla_nest_start(skb, state->policy_idx);
if (!policy)
return -ENOBUFS;
attr = nla_nest_start(skb, state->attr_idx);
if (!attr)
goto nla_put_failure;
switch (pt->type) {
default:
case NLA_UNSPEC:
case NLA_REJECT:
/* skip - use NLA_MIN_LEN to advertise such */
nla_nest_cancel(skb, policy);
again = true;
goto next;
case NLA_NESTED:
type = NL_ATTR_TYPE_NESTED;
fallthrough;
case NLA_NESTED_ARRAY:
if (pt->type == NLA_NESTED_ARRAY)
type = NL_ATTR_TYPE_NESTED_ARRAY;
if (pt->nested_policy && pt->len &&
(nla_put_u32(skb, NL_POLICY_TYPE_ATTR_POLICY_IDX,
get_policy_idx(state, pt->nested_policy,
pt->len)) ||
nla_put_u32(skb, NL_POLICY_TYPE_ATTR_POLICY_MAXTYPE,
pt->len)))
goto nla_put_failure;
break;
case NLA_U8:
case NLA_U16:
case NLA_U32:
case NLA_U64:
case NLA_MSECS: {
struct netlink_range_validation range;
if (pt->type == NLA_U8)
type = NL_ATTR_TYPE_U8;
else if (pt->type == NLA_U16)
type = NL_ATTR_TYPE_U16;
else if (pt->type == NLA_U32)
type = NL_ATTR_TYPE_U32;
else
type = NL_ATTR_TYPE_U64;
nla_get_range_unsigned(pt, &range);
if (nla_put_u64_64bit(skb, NL_POLICY_TYPE_ATTR_MIN_VALUE_U,
range.min, NL_POLICY_TYPE_ATTR_PAD) ||
nla_put_u64_64bit(skb, NL_POLICY_TYPE_ATTR_MAX_VALUE_U,
range.max, NL_POLICY_TYPE_ATTR_PAD))
goto nla_put_failure;
break;
}
case NLA_S8:
case NLA_S16:
case NLA_S32:
case NLA_S64: {
struct netlink_range_validation_signed range;
if (pt->type == NLA_S8)
type = NL_ATTR_TYPE_S8;
else if (pt->type == NLA_S16)
type = NL_ATTR_TYPE_S16;
else if (pt->type == NLA_S32)
type = NL_ATTR_TYPE_S32;
else
type = NL_ATTR_TYPE_S64;
nla_get_range_signed(pt, &range);
if (nla_put_s64(skb, NL_POLICY_TYPE_ATTR_MIN_VALUE_S,
range.min, NL_POLICY_TYPE_ATTR_PAD) ||
nla_put_s64(skb, NL_POLICY_TYPE_ATTR_MAX_VALUE_S,
range.max, NL_POLICY_TYPE_ATTR_PAD))
goto nla_put_failure;
break;
}
case NLA_BITFIELD32:
type = NL_ATTR_TYPE_BITFIELD32;
if (nla_put_u32(skb, NL_POLICY_TYPE_ATTR_BITFIELD32_MASK,
pt->bitfield32_valid))
goto nla_put_failure;
break;
case NLA_STRING:
case NLA_NUL_STRING:
case NLA_BINARY:
if (pt->type == NLA_STRING)
type = NL_ATTR_TYPE_STRING;
else if (pt->type == NLA_NUL_STRING)
type = NL_ATTR_TYPE_NUL_STRING;
else
type = NL_ATTR_TYPE_BINARY;
if (pt->validation_type == NLA_VALIDATE_RANGE ||
pt->validation_type == NLA_VALIDATE_RANGE_WARN_TOO_LONG) {
struct netlink_range_validation range;
nla_get_range_unsigned(pt, &range);
if (range.min &&
nla_put_u32(skb, NL_POLICY_TYPE_ATTR_MIN_LENGTH,
range.min))
goto nla_put_failure;
if (range.max < U16_MAX &&
nla_put_u32(skb, NL_POLICY_TYPE_ATTR_MAX_LENGTH,
range.max))
goto nla_put_failure;
} else if (pt->len &&
nla_put_u32(skb, NL_POLICY_TYPE_ATTR_MAX_LENGTH,
pt->len)) {
goto nla_put_failure;
}
break;
case NLA_FLAG:
type = NL_ATTR_TYPE_FLAG;
break;
}
if (nla_put_u32(skb, NL_POLICY_TYPE_ATTR_TYPE, type))
goto nla_put_failure;
/* finish and move state to next attribute */
nla_nest_end(skb, attr);
nla_nest_end(skb, policy);
next:
state->attr_idx += 1;
if (state->attr_idx > state->policies[state->policy_idx].maxtype) {
state->attr_idx = 0;
state->policy_idx++;
}
if (again) {
if (netlink_policy_dump_finished(state))
return -ENODATA;
goto send_attribute;
}
return 0;
nla_put_failure:
nla_nest_cancel(skb, policy);
return -ENOBUFS;
}
void netlink_policy_dump_free(struct netlink_policy_dump_state *state)
{
kfree(state);
}
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