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netfilter: nf_tables: get set elements via netlink
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This patch adds a new get operation to look up for specific elements in
a set via netlink interface. You can also use it to check if an interval
already exists.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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Pablo Neira Ayuso committed Nov 7, 2017
1 parent 644e334 commit ba0e4d9
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Showing 5 changed files with 264 additions and 55 deletions.
5 changes: 5 additions & 0 deletions include/net/netfilter/nf_tables.h
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Original file line number Diff line number Diff line change
Expand Up @@ -311,6 +311,7 @@ struct nft_expr;
* @flush: deactivate element in the next generation
* @remove: remove element from set
* @walk: iterate over all set elemeennts
* @get: get set elements
* @privsize: function to return size of set private data
* @init: initialize private data of new set instance
* @destroy: destroy private data of set instance
Expand Down Expand Up @@ -350,6 +351,10 @@ struct nft_set_ops {
void (*walk)(const struct nft_ctx *ctx,
struct nft_set *set,
struct nft_set_iter *iter);
void * (*get)(const struct net *net,
const struct nft_set *set,
const struct nft_set_elem *elem,
unsigned int flags);

unsigned int (*privsize)(const struct nlattr * const nla[],
const struct nft_set_desc *desc);
Expand Down
184 changes: 129 additions & 55 deletions net/netfilter/nf_tables_api.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -3586,45 +3586,6 @@ static int nf_tables_dump_set_done(struct netlink_callback *cb)
return 0;
}

static int nf_tables_getsetelem(struct net *net, struct sock *nlsk,
struct sk_buff *skb, const struct nlmsghdr *nlh,
const struct nlattr * const nla[],
struct netlink_ext_ack *extack)
{
u8 genmask = nft_genmask_cur(net);
const struct nft_set *set;
struct nft_ctx ctx;
int err;

err = nft_ctx_init_from_elemattr(&ctx, net, skb, nlh, nla, genmask);
if (err < 0)
return err;

set = nf_tables_set_lookup(ctx.table, nla[NFTA_SET_ELEM_LIST_SET],
genmask);
if (IS_ERR(set))
return PTR_ERR(set);

if (nlh->nlmsg_flags & NLM_F_DUMP) {
struct netlink_dump_control c = {
.dump = nf_tables_dump_set,
.done = nf_tables_dump_set_done,
};
struct nft_set_dump_ctx *dump_ctx;

dump_ctx = kmalloc(sizeof(*dump_ctx), GFP_KERNEL);
if (!dump_ctx)
return -ENOMEM;

dump_ctx->set = set;
dump_ctx->ctx = ctx;

c.data = dump_ctx;
return netlink_dump_start(nlsk, skb, nlh, &c);
}
return -EOPNOTSUPP;
}

static int nf_tables_fill_setelem_info(struct sk_buff *skb,
const struct nft_ctx *ctx, u32 seq,
u32 portid, int event, u16 flags,
Expand Down Expand Up @@ -3670,6 +3631,135 @@ static int nf_tables_fill_setelem_info(struct sk_buff *skb,
return -1;
}

static int nft_setelem_parse_flags(const struct nft_set *set,
const struct nlattr *attr, u32 *flags)
{
if (attr == NULL)
return 0;

*flags = ntohl(nla_get_be32(attr));
if (*flags & ~NFT_SET_ELEM_INTERVAL_END)
return -EINVAL;
if (!(set->flags & NFT_SET_INTERVAL) &&
*flags & NFT_SET_ELEM_INTERVAL_END)
return -EINVAL;

return 0;
}

static int nft_get_set_elem(struct nft_ctx *ctx, struct nft_set *set,
const struct nlattr *attr)
{
struct nlattr *nla[NFTA_SET_ELEM_MAX + 1];
const struct nft_set_ext *ext;
struct nft_data_desc desc;
struct nft_set_elem elem;
struct sk_buff *skb;
uint32_t flags = 0;
void *priv;
int err;

err = nla_parse_nested(nla, NFTA_SET_ELEM_MAX, attr,
nft_set_elem_policy, NULL);
if (err < 0)
return err;

if (!nla[NFTA_SET_ELEM_KEY])
return -EINVAL;

err = nft_setelem_parse_flags(set, nla[NFTA_SET_ELEM_FLAGS], &flags);
if (err < 0)
return err;

err = nft_data_init(ctx, &elem.key.val, sizeof(elem.key), &desc,
nla[NFTA_SET_ELEM_KEY]);
if (err < 0)
return err;

err = -EINVAL;
if (desc.type != NFT_DATA_VALUE || desc.len != set->klen)
return err;

priv = set->ops->get(ctx->net, set, &elem, flags);
if (IS_ERR(priv))
return PTR_ERR(priv);

elem.priv = priv;
ext = nft_set_elem_ext(set, &elem);

err = -ENOMEM;
skb = nlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL);
if (skb == NULL)
goto err1;

err = nf_tables_fill_setelem_info(skb, ctx, ctx->seq, ctx->portid,
NFT_MSG_NEWSETELEM, 0, set, &elem);
if (err < 0)
goto err2;

err = nfnetlink_unicast(skb, ctx->net, ctx->portid, MSG_DONTWAIT);
/* This avoids a loop in nfnetlink. */
if (err < 0)
goto err1;

return 0;
err2:
kfree_skb(skb);
err1:
/* this avoids a loop in nfnetlink. */
return err == -EAGAIN ? -ENOBUFS : err;
}

static int nf_tables_getsetelem(struct net *net, struct sock *nlsk,
struct sk_buff *skb, const struct nlmsghdr *nlh,
const struct nlattr * const nla[],
struct netlink_ext_ack *extack)
{
u8 genmask = nft_genmask_cur(net);
struct nft_set *set;
struct nlattr *attr;
struct nft_ctx ctx;
int rem, err = 0;

err = nft_ctx_init_from_elemattr(&ctx, net, skb, nlh, nla, genmask);
if (err < 0)
return err;

set = nf_tables_set_lookup(ctx.table, nla[NFTA_SET_ELEM_LIST_SET],
genmask);
if (IS_ERR(set))
return PTR_ERR(set);

if (nlh->nlmsg_flags & NLM_F_DUMP) {
struct netlink_dump_control c = {
.dump = nf_tables_dump_set,
.done = nf_tables_dump_set_done,
};
struct nft_set_dump_ctx *dump_ctx;

dump_ctx = kmalloc(sizeof(*dump_ctx), GFP_KERNEL);
if (!dump_ctx)
return -ENOMEM;

dump_ctx->set = set;
dump_ctx->ctx = ctx;

c.data = dump_ctx;
return netlink_dump_start(nlsk, skb, nlh, &c);
}

if (!nla[NFTA_SET_ELEM_LIST_ELEMENTS])
return -EINVAL;

nla_for_each_nested(attr, nla[NFTA_SET_ELEM_LIST_ELEMENTS], rem) {
err = nft_get_set_elem(&ctx, set, attr);
if (err < 0)
break;
}

return err;
}

static void nf_tables_setelem_notify(const struct nft_ctx *ctx,
const struct nft_set *set,
const struct nft_set_elem *elem,
Expand Down Expand Up @@ -3770,22 +3860,6 @@ static void nf_tables_set_elem_destroy(const struct nft_set *set, void *elem)
kfree(elem);
}

static int nft_setelem_parse_flags(const struct nft_set *set,
const struct nlattr *attr, u32 *flags)
{
if (attr == NULL)
return 0;

*flags = ntohl(nla_get_be32(attr));
if (*flags & ~NFT_SET_ELEM_INTERVAL_END)
return -EINVAL;
if (!(set->flags & NFT_SET_INTERVAL) &&
*flags & NFT_SET_ELEM_INTERVAL_END)
return -EINVAL;

return 0;
}

static int nft_add_set_elem(struct nft_ctx *ctx, struct nft_set *set,
const struct nlattr *attr, u32 nlmsg_flags)
{
Expand Down
18 changes: 18 additions & 0 deletions net/netfilter/nft_set_bitmap.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -106,6 +106,23 @@ nft_bitmap_elem_find(const struct nft_set *set, struct nft_bitmap_elem *this,
return NULL;
}

static void *nft_bitmap_get(const struct net *net, const struct nft_set *set,
const struct nft_set_elem *elem, unsigned int flags)
{
const struct nft_bitmap *priv = nft_set_priv(set);
u8 genmask = nft_genmask_cur(net);
struct nft_bitmap_elem *be;

list_for_each_entry_rcu(be, &priv->list, head) {
if (memcmp(nft_set_ext_key(&be->ext), elem->key.val.data, set->klen) ||
!nft_set_elem_active(&be->ext, genmask))
continue;

return be;
}
return ERR_PTR(-ENOENT);
}

static int nft_bitmap_insert(const struct net *net, const struct nft_set *set,
const struct nft_set_elem *elem,
struct nft_set_ext **ext)
Expand Down Expand Up @@ -294,6 +311,7 @@ static struct nft_set_ops nft_bitmap_ops __read_mostly = {
.activate = nft_bitmap_activate,
.lookup = nft_bitmap_lookup,
.walk = nft_bitmap_walk,
.get = nft_bitmap_get,
};

static struct nft_set_type nft_bitmap_type __read_mostly = {
Expand Down
39 changes: 39 additions & 0 deletions net/netfilter/nft_set_hash.c
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Original file line number Diff line number Diff line change
Expand Up @@ -95,6 +95,24 @@ static bool nft_rhash_lookup(const struct net *net, const struct nft_set *set,
return !!he;
}

static void *nft_rhash_get(const struct net *net, const struct nft_set *set,
const struct nft_set_elem *elem, unsigned int flags)
{
struct nft_rhash *priv = nft_set_priv(set);
struct nft_rhash_elem *he;
struct nft_rhash_cmp_arg arg = {
.genmask = nft_genmask_cur(net),
.set = set,
.key = elem->key.val.data,
};

he = rhashtable_lookup_fast(&priv->ht, &arg, nft_rhash_params);
if (he != NULL)
return he;

return ERR_PTR(-ENOENT);
}

static bool nft_rhash_update(struct nft_set *set, const u32 *key,
void *(*new)(struct nft_set *,
const struct nft_expr *,
Expand Down Expand Up @@ -409,6 +427,24 @@ static bool nft_hash_lookup(const struct net *net, const struct nft_set *set,
return false;
}

static void *nft_hash_get(const struct net *net, const struct nft_set *set,
const struct nft_set_elem *elem, unsigned int flags)
{
struct nft_hash *priv = nft_set_priv(set);
u8 genmask = nft_genmask_cur(net);
struct nft_hash_elem *he;
u32 hash;

hash = jhash(elem->key.val.data, set->klen, priv->seed);
hash = reciprocal_scale(hash, priv->buckets);
hlist_for_each_entry_rcu(he, &priv->table[hash], node) {
if (!memcmp(nft_set_ext_key(&he->ext), elem->key.val.data, set->klen) &&
nft_set_elem_active(&he->ext, genmask))
return he;
}
return ERR_PTR(-ENOENT);
}

/* nft_hash_select_ops() makes sure key size can be either 2 or 4 bytes . */
static inline u32 nft_hash_key(const u32 *key, u32 klen)
{
Expand Down Expand Up @@ -600,6 +636,7 @@ static struct nft_set_ops nft_rhash_ops __read_mostly = {
.lookup = nft_rhash_lookup,
.update = nft_rhash_update,
.walk = nft_rhash_walk,
.get = nft_rhash_get,
.features = NFT_SET_MAP | NFT_SET_OBJECT | NFT_SET_TIMEOUT,
};

Expand All @@ -617,6 +654,7 @@ static struct nft_set_ops nft_hash_ops __read_mostly = {
.remove = nft_hash_remove,
.lookup = nft_hash_lookup,
.walk = nft_hash_walk,
.get = nft_hash_get,
.features = NFT_SET_MAP | NFT_SET_OBJECT,
};

Expand All @@ -634,6 +672,7 @@ static struct nft_set_ops nft_hash_fast_ops __read_mostly = {
.remove = nft_hash_remove,
.lookup = nft_hash_lookup_fast,
.walk = nft_hash_walk,
.get = nft_hash_get,
.features = NFT_SET_MAP | NFT_SET_OBJECT,
};

Expand Down
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