[PATCH 0/3] Add userdata and comment support for tables

[PATCH 0/3] Add userdata and comment support for tables

[Jose M. Guisado Gomez]

This patch series enables storing userdata for tables. In addition,
using this userdata to save an optional comment when declaring new tables. 

 * nf-next
 netfilter: nf_tables: add userdata attributes to nft_table

 include/net/netfilter/nf_tables.h        |  2 ++
 include/uapi/linux/netfilter/nf_tables.h |  2 ++
 net/netfilter/nf_tables_api.c            | 25 ++++++++++++++++++++++++
 3 files changed, 29 insertions(+)
 
 * libnftnlt
 table: add userdata support

 include/libnftnl/table.h            |  1 +
 include/libnftnl/udata.h            |  6 ++++++
 include/linux/netfilter/nf_tables.h |  1 +
 src/table.c                         | 33 +++++++++++++++++++++++++++++
 4 files changed, 41 insertions(+)

 * nftables
 src: add comment support when adding tables

 include/rule.h                                |  1 +
 src/mnl.c                                     | 19 +++++++++--
 src/netlink.c                                 | 32 +++++++++++++++++++
 src/parser_bison.y                            |  4 +++
 src/rule.c                                    |  5 +++
 .../testcases/optionals/comments_table_0      |  0
 .../testcases/optionals/comments_table_1      |  0
 .../optionals/dumps/comments_table_0.nft      |  0
 .../optionals/dumps/comments_table_1.nft      |  0
 9 files changed, 59 insertions(+), 2 deletions(-)
 create mode 100755 tests/shell/testcases/optionals/comments_table_0
 create mode 100755 tests/shell/testcases/optionals/comments_table_1
 create mode 100644 tests/shell/testcases/optionals/dumps/comments_table_0.nft
 create mode 100644 tests/shell/testcases/optionals/dumps/comments_table_1.nft

-- 
2.27.0

[PATCH nf-next 1/3] netfilter: nf_tables: add userdata attributes to nft_table

[Jose M. Guisado Gomez]

Enables storing userdata for nft_table. Field udata points to user data
and udlen store its length.

Adds new attribute flag NFTA_TABLE_USERDATA

Signed-off-by: Jose M. Guisado Gomez <guigom@riseup.net>
---
 include/net/netfilter/nf_tables.h        |  2 ++
 include/uapi/linux/netfilter/nf_tables.h |  2 ++
 net/netfilter/nf_tables_api.c            | 25 ++++++++++++++++++++++++
 3 files changed, 29 insertions(+)

diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h
index bf9491b77d16..97a7e147a59a 100644
--- a/include/net/netfilter/nf_tables.h
+++ b/include/net/netfilter/nf_tables.h
@@ -1080,6 +1080,8 @@ struct nft_table {
 					flags:8,
 					genmask:2;
 	char				*name;
+	u16				udlen;
+	u8				*udata;
 };
 
 void nft_register_chain_type(const struct nft_chain_type *);
diff --git a/include/uapi/linux/netfilter/nf_tables.h b/include/uapi/linux/netfilter/nf_tables.h
index 42f351c1f5c5..aeb88cbd303e 100644
--- a/include/uapi/linux/netfilter/nf_tables.h
+++ b/include/uapi/linux/netfilter/nf_tables.h
@@ -172,6 +172,7 @@ enum nft_table_flags {
  * @NFTA_TABLE_NAME: name of the table (NLA_STRING)
  * @NFTA_TABLE_FLAGS: bitmask of enum nft_table_flags (NLA_U32)
  * @NFTA_TABLE_USE: number of chains in this table (NLA_U32)
+ * @NFTA_TABLE_USERDATA: user data (NLA_BINARY)
  */
 enum nft_table_attributes {
 	NFTA_TABLE_UNSPEC,
@@ -180,6 +181,7 @@ enum nft_table_attributes {
 	NFTA_TABLE_USE,
 	NFTA_TABLE_HANDLE,
 	NFTA_TABLE_PAD,
+	NFTA_TABLE_USERDATA,
 	__NFTA_TABLE_MAX
 };
 #define NFTA_TABLE_MAX		(__NFTA_TABLE_MAX - 1)
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index d878e34e3354..ca240a990eea 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -650,6 +650,8 @@ static const struct nla_policy nft_table_policy[NFTA_TABLE_MAX + 1] = {
 				    .len = NFT_TABLE_MAXNAMELEN - 1 },
 	[NFTA_TABLE_FLAGS]	= { .type = NLA_U32 },
 	[NFTA_TABLE_HANDLE]	= { .type = NLA_U64 },
+	[NFTA_TABLE_USERDATA]	= { .type = NLA_BINARY,
+				    .len = NFT_USERDATA_MAXLEN }
 };
 
 static int nf_tables_fill_table_info(struct sk_buff *skb, struct net *net,
@@ -676,6 +678,11 @@ static int nf_tables_fill_table_info(struct sk_buff *skb, struct net *net,
 			 NFTA_TABLE_PAD))
 		goto nla_put_failure;
 
+	if (table->udata) {
+		if (nla_put(skb, NFTA_TABLE_USERDATA, table->udlen, table->udata))
+			goto nla_put_failure;
+	}
+
 	nlmsg_end(skb, nlh);
 	return 0;
 
@@ -980,6 +987,7 @@ static int nf_tables_newtable(struct net *net, struct sock *nlsk,
 	u32 flags = 0;
 	struct nft_ctx ctx;
 	int err;
+	u16 udlen = 0;
 
 	lockdep_assert_held(&net->nft.commit_mutex);
 	attr = nla[NFTA_TABLE_NAME];
@@ -1005,6 +1013,7 @@ static int nf_tables_newtable(struct net *net, struct sock *nlsk,
 			return -EINVAL;
 	}
 
+
 	err = -ENOMEM;
 	table = kzalloc(sizeof(*table), GFP_KERNEL);
 	if (table == NULL)
@@ -1014,6 +1023,20 @@ static int nf_tables_newtable(struct net *net, struct sock *nlsk,
 	if (table->name == NULL)
 		goto err_strdup;
 
+	if (nla[NFTA_TABLE_USERDATA]) {
+		udlen = nla_len(nla[NFTA_TABLE_USERDATA]);
+		table->udata = kzalloc(udlen, GFP_KERNEL);
+		if (table->udata == NULL)
+			goto err_table_udata;
+	} else {
+		table->udata = NULL;
+	}
+
+	if (udlen) {
+		nla_memcpy(table->udata, nla[NFTA_TABLE_USERDATA], udlen);
+		table->udlen = udlen;
+	}
+
 	err = rhltable_init(&table->chains_ht, &nft_chain_ht_params);
 	if (err)
 		goto err_chain_ht;
@@ -1036,6 +1059,8 @@ static int nf_tables_newtable(struct net *net, struct sock *nlsk,
 err_trans:
 	rhltable_destroy(&table->chains_ht);
 err_chain_ht:
+	kfree(table->udata);
+err_table_udata:
 	kfree(table->name);
 err_strdup:
 	kfree(table);
-- 
2.27.0

Re: [PATCH nf-next 1/3] netfilter: nf_tables: add userdata attributes to nft_table

[Pablo Neira Ayuso]

On Thu, Aug 20, 2020 at 10:19:01AM +0200, Jose M. Guisado Gomez wrote:
> Enables storing userdata for nft_table. Field udata points to user data
> and udlen store its length.
> 
> Adds new attribute flag NFTA_TABLE_USERDATA
> 
> Signed-off-by: Jose M. Guisado Gomez <guigom@riseup.net>
> ---
>  include/net/netfilter/nf_tables.h        |  2 ++
>  include/uapi/linux/netfilter/nf_tables.h |  2 ++
>  net/netfilter/nf_tables_api.c            | 25 ++++++++++++++++++++++++
>  3 files changed, 29 insertions(+)
> 
> diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h
> index bf9491b77d16..97a7e147a59a 100644
> --- a/include/net/netfilter/nf_tables.h
> +++ b/include/net/netfilter/nf_tables.h
> @@ -1080,6 +1080,8 @@ struct nft_table {
>  					flags:8,
>  					genmask:2;
>  	char				*name;
> +	u16				udlen;
> +	u8				*udata;
>  };
>  
>  void nft_register_chain_type(const struct nft_chain_type *);
> diff --git a/include/uapi/linux/netfilter/nf_tables.h b/include/uapi/linux/netfilter/nf_tables.h
> index 42f351c1f5c5..aeb88cbd303e 100644
> --- a/include/uapi/linux/netfilter/nf_tables.h
> +++ b/include/uapi/linux/netfilter/nf_tables.h
> @@ -172,6 +172,7 @@ enum nft_table_flags {
>   * @NFTA_TABLE_NAME: name of the table (NLA_STRING)
>   * @NFTA_TABLE_FLAGS: bitmask of enum nft_table_flags (NLA_U32)
>   * @NFTA_TABLE_USE: number of chains in this table (NLA_U32)
> + * @NFTA_TABLE_USERDATA: user data (NLA_BINARY)
>   */
>  enum nft_table_attributes {
>  	NFTA_TABLE_UNSPEC,
> @@ -180,6 +181,7 @@ enum nft_table_attributes {
>  	NFTA_TABLE_USE,
>  	NFTA_TABLE_HANDLE,
>  	NFTA_TABLE_PAD,
> +	NFTA_TABLE_USERDATA,
>  	__NFTA_TABLE_MAX
>  };
>  #define NFTA_TABLE_MAX		(__NFTA_TABLE_MAX - 1)
> diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
> index d878e34e3354..ca240a990eea 100644
> --- a/net/netfilter/nf_tables_api.c
> +++ b/net/netfilter/nf_tables_api.c
> @@ -650,6 +650,8 @@ static const struct nla_policy nft_table_policy[NFTA_TABLE_MAX + 1] = {
>  				    .len = NFT_TABLE_MAXNAMELEN - 1 },
>  	[NFTA_TABLE_FLAGS]	= { .type = NLA_U32 },
>  	[NFTA_TABLE_HANDLE]	= { .type = NLA_U64 },
> +	[NFTA_TABLE_USERDATA]	= { .type = NLA_BINARY,
> +				    .len = NFT_USERDATA_MAXLEN }
>  };
>  
>  static int nf_tables_fill_table_info(struct sk_buff *skb, struct net *net,
> @@ -676,6 +678,11 @@ static int nf_tables_fill_table_info(struct sk_buff *skb, struct net *net,
>  			 NFTA_TABLE_PAD))
>  		goto nla_put_failure;
>  
> +	if (table->udata) {
> +		if (nla_put(skb, NFTA_TABLE_USERDATA, table->udlen, table->udata))
> +			goto nla_put_failure;
> +	}
> +
>  	nlmsg_end(skb, nlh);
>  	return 0;
>  
> @@ -980,6 +987,7 @@ static int nf_tables_newtable(struct net *net, struct sock *nlsk,
>  	u32 flags = 0;
>  	struct nft_ctx ctx;
>  	int err;
> +	u16 udlen = 0;
>  
>  	lockdep_assert_held(&net->nft.commit_mutex);
>  	attr = nla[NFTA_TABLE_NAME];
> @@ -1005,6 +1013,7 @@ static int nf_tables_newtable(struct net *net, struct sock *nlsk,
>  			return -EINVAL;
>  	}
>  
> +
>  	err = -ENOMEM;
>  	table = kzalloc(sizeof(*table), GFP_KERNEL);
>  	if (table == NULL)
> @@ -1014,6 +1023,20 @@ static int nf_tables_newtable(struct net *net, struct sock *nlsk,
>  	if (table->name == NULL)
>  		goto err_strdup;
>  
> +	if (nla[NFTA_TABLE_USERDATA]) {
> +		udlen = nla_len(nla[NFTA_TABLE_USERDATA]);
> +		table->udata = kzalloc(udlen, GFP_KERNEL);
> +		if (table->udata == NULL)
> +			goto err_table_udata;
> +	} else {
> +		table->udata = NULL;
> +	}
> +
> +	if (udlen) {
> +		nla_memcpy(table->udata, nla[NFTA_TABLE_USERDATA], udlen);
> +		table->udlen = udlen;
> +	}

       if (nla[NFTA_TABLE_USERDATA]) {
               udlen = nla_len(nla[NFTA_TABLE_USERDATA]);
               table->udata = kzalloc(udlen, GFP_KERNEL);
               if (table->udata == NULL)
                       goto err_table_udata;

               nla_memcpy(table->udata, nla[NFTA_TABLE_USERDATA], udlen);
               table->udlen = udlen;
       }

Probably this simplification instead? kzalloc() zeroes the table
object, so table->udata is NULL and ->udlen is zero.

Re: [PATCH nf-next 1/3] netfilter: nf_tables: add userdata attributes to nft_table

[Jose M. Guisado]

On 21/8/20 19:21, Pablo Neira Ayuso wrote:
>         if (nla[NFTA_TABLE_USERDATA]) {
>                 udlen = nla_len(nla[NFTA_TABLE_USERDATA]);
>                 table->udata = kzalloc(udlen, GFP_KERNEL);
>                 if (table->udata == NULL)
>                         goto err_table_udata;
> 
>                 nla_memcpy(table->udata, nla[NFTA_TABLE_USERDATA], udlen);
>                 table->udlen = udlen;
>         }
> 
> Probably this simplification instead? kzalloc() zeroes the table
> object, so table->udata is NULL and ->udlen is zero.

I see. The reason why I didn't simplify at first was because when using 
other nf_tables_new* functions with userdata support as reference (like 
newset or newrule), these are checking for userdata length obtained via 
nla_len before calling nla_memcpy.

[PATCH nf-next v2 1/3] netfilter: nf_tables: add userdata attributes to nft_table

[Jose M. Guisado Gomez]

Enables storing userdata for nft_table. Field udata points to user data
and udlen store its length.

Adds new attribute flag NFTA_TABLE_USERDATA

Signed-off-by: Jose M. Guisado Gomez <guigom@riseup.net>
---
 include/net/netfilter/nf_tables.h        |  2 ++
 include/uapi/linux/netfilter/nf_tables.h |  2 ++
 net/netfilter/nf_tables_api.c            | 20 ++++++++++++++++++++
 3 files changed, 24 insertions(+)

diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h
index bf9491b77d16..97a7e147a59a 100644
--- a/include/net/netfilter/nf_tables.h
+++ b/include/net/netfilter/nf_tables.h
@@ -1080,6 +1080,8 @@ struct nft_table {
 					flags:8,
 					genmask:2;
 	char				*name;
+	u16				udlen;
+	u8				*udata;
 };
 
 void nft_register_chain_type(const struct nft_chain_type *);
diff --git a/include/uapi/linux/netfilter/nf_tables.h b/include/uapi/linux/netfilter/nf_tables.h
index 42f351c1f5c5..aeb88cbd303e 100644
--- a/include/uapi/linux/netfilter/nf_tables.h
+++ b/include/uapi/linux/netfilter/nf_tables.h
@@ -172,6 +172,7 @@ enum nft_table_flags {
  * @NFTA_TABLE_NAME: name of the table (NLA_STRING)
  * @NFTA_TABLE_FLAGS: bitmask of enum nft_table_flags (NLA_U32)
  * @NFTA_TABLE_USE: number of chains in this table (NLA_U32)
+ * @NFTA_TABLE_USERDATA: user data (NLA_BINARY)
  */
 enum nft_table_attributes {
 	NFTA_TABLE_UNSPEC,
@@ -180,6 +181,7 @@ enum nft_table_attributes {
 	NFTA_TABLE_USE,
 	NFTA_TABLE_HANDLE,
 	NFTA_TABLE_PAD,
+	NFTA_TABLE_USERDATA,
 	__NFTA_TABLE_MAX
 };
 #define NFTA_TABLE_MAX		(__NFTA_TABLE_MAX - 1)
diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index d878e34e3354..5e9d347780c1 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -650,6 +650,8 @@ static const struct nla_policy nft_table_policy[NFTA_TABLE_MAX + 1] = {
 				    .len = NFT_TABLE_MAXNAMELEN - 1 },
 	[NFTA_TABLE_FLAGS]	= { .type = NLA_U32 },
 	[NFTA_TABLE_HANDLE]	= { .type = NLA_U64 },
+	[NFTA_TABLE_USERDATA]	= { .type = NLA_BINARY,
+				    .len = NFT_USERDATA_MAXLEN }
 };
 
 static int nf_tables_fill_table_info(struct sk_buff *skb, struct net *net,
@@ -676,6 +678,11 @@ static int nf_tables_fill_table_info(struct sk_buff *skb, struct net *net,
 			 NFTA_TABLE_PAD))
 		goto nla_put_failure;
 
+	if (table->udata) {
+		if (nla_put(skb, NFTA_TABLE_USERDATA, table->udlen, table->udata))
+			goto nla_put_failure;
+	}
+
 	nlmsg_end(skb, nlh);
 	return 0;
 
@@ -980,6 +987,7 @@ static int nf_tables_newtable(struct net *net, struct sock *nlsk,
 	u32 flags = 0;
 	struct nft_ctx ctx;
 	int err;
+	u16 udlen = 0;
 
 	lockdep_assert_held(&net->nft.commit_mutex);
 	attr = nla[NFTA_TABLE_NAME];
@@ -1014,6 +1022,16 @@ static int nf_tables_newtable(struct net *net, struct sock *nlsk,
 	if (table->name == NULL)
 		goto err_strdup;
 
+	if (nla[NFTA_TABLE_USERDATA]) {
+		udlen = nla_len(nla[NFTA_TABLE_USERDATA]);
+		table->udata = kzalloc(udlen, GFP_KERNEL);
+		if (table->udata == NULL)
+			goto err_table_udata;
+
+		nla_memcpy(table->udata, nla[NFTA_TABLE_USERDATA], udlen);
+		table->udlen = udlen;
+	}
+
 	err = rhltable_init(&table->chains_ht, &nft_chain_ht_params);
 	if (err)
 		goto err_chain_ht;
@@ -1036,6 +1054,8 @@ static int nf_tables_newtable(struct net *net, struct sock *nlsk,
 err_trans:
 	rhltable_destroy(&table->chains_ht);
 err_chain_ht:
+	kfree(table->udata);
+err_table_udata:
 	kfree(table->name);
 err_strdup:
 	kfree(table);
-- 
2.27.0

Re: [PATCH nf-next v2 1/3] netfilter: nf_tables: add userdata attributes to nft_table

[Pablo Neira Ayuso]

On Sat, Aug 22, 2020 at 11:09:30AM +0200, Jose M. Guisado Gomez wrote:
> Enables storing userdata for nft_table. Field udata points to user data
> and udlen store its length.
> 
> Adds new attribute flag NFTA_TABLE_USERDATA

Applied, thanks.

[PATCH libnftnl 2/3] table: add userdata support

[Jose M. Guisado Gomez]

Signed-off-by: Jose M. Guisado Gomez <guigom@riseup.net>
---
 include/libnftnl/table.h            |  1 +
 include/libnftnl/udata.h            |  6 ++++++
 include/linux/netfilter/nf_tables.h |  1 +
 src/table.c                         | 33 +++++++++++++++++++++++++++++
 4 files changed, 41 insertions(+)

diff --git a/include/libnftnl/table.h b/include/libnftnl/table.h
index 5faec81..a37fba2 100644
--- a/include/libnftnl/table.h
+++ b/include/libnftnl/table.h
@@ -23,6 +23,7 @@ enum nftnl_table_attr {
 	NFTNL_TABLE_FLAGS,
 	NFTNL_TABLE_USE,
 	NFTNL_TABLE_HANDLE,
+	NFTNL_TABLE_USERDATA,
 	__NFTNL_TABLE_MAX
 };
 #define NFTNL_TABLE_MAX (__NFTNL_TABLE_MAX - 1)
diff --git a/include/libnftnl/udata.h b/include/libnftnl/udata.h
index efa3f76..ba6b3ab 100644
--- a/include/libnftnl/udata.h
+++ b/include/libnftnl/udata.h
@@ -9,6 +9,12 @@
 extern "C" {
 #endif
 
+enum nftnl_udata_table_types {
+	NFTNL_UDATA_TABLE_COMMENT,
+	__NFTNL_UDATA_TABLE_MAX
+};
+#define NFTNL_UDATA_TABLE_MAX (__NFTNL_UDATA_TABLE_MAX - 1)
+
 enum nftnl_udata_rule_types {
 	NFTNL_UDATA_RULE_COMMENT,
 	NFTNL_UDATA_RULE_EBTABLES_POLICY,
diff --git a/include/linux/netfilter/nf_tables.h b/include/linux/netfilter/nf_tables.h
index d9b0daa..d508154 100644
--- a/include/linux/netfilter/nf_tables.h
+++ b/include/linux/netfilter/nf_tables.h
@@ -180,6 +180,7 @@ enum nft_table_attributes {
 	NFTA_TABLE_USE,
 	NFTA_TABLE_HANDLE,
 	NFTA_TABLE_PAD,
+	NFTA_TABLE_USERDATA,
 	__NFTA_TABLE_MAX
 };
 #define NFTA_TABLE_MAX		(__NFTA_TABLE_MAX - 1)
diff --git a/src/table.c b/src/table.c
index 94d522b..731c818 100644
--- a/src/table.c
+++ b/src/table.c
@@ -34,6 +34,10 @@ struct nftnl_table {
 	uint64_t 	handle;
 	uint32_t	use;
 	uint32_t	flags;
+	struct {
+		void		*data;
+		uint32_t	len;
+	} user;
 };
 
 EXPORT_SYMBOL(nftnl_table_alloc);
@@ -47,6 +51,8 @@ void nftnl_table_free(const struct nftnl_table *t)
 {
 	if (t->flags & (1 << NFTNL_TABLE_NAME))
 		xfree(t->name);
+	if (t->flags & (1 << NFTNL_TABLE_USERDATA))
+		xfree(t->user.data);
 
 	xfree(t);
 }
@@ -111,6 +117,16 @@ int nftnl_table_set_data(struct nftnl_table *t, uint16_t attr,
 	case NFTNL_TABLE_USE:
 		memcpy(&t->use, data, sizeof(t->use));
 		break;
+	case NFTNL_TABLE_USERDATA:
+		if (t->flags & (1 << NFTNL_TABLE_USERDATA))
+			xfree(t->user.data);
+
+		t->user.data = malloc(data_len);
+		if (!t->user.data)
+			return -1;
+		memcpy(t->user.data, data, data_len);
+		t->user.len = data_len;
+		break;
 	}
 	t->flags |= (1 << attr);
 	return 0;
@@ -169,6 +185,9 @@ const void *nftnl_table_get_data(const struct nftnl_table *t, uint16_t attr,
 	case NFTNL_TABLE_USE:
 		*data_len = sizeof(uint32_t);
 		return &t->use;
+	case NFTNL_TABLE_USERDATA:
+		*data_len = t->user.len;
+		return t->user.data;
 	}
 	return NULL;
 }
@@ -216,6 +235,8 @@ void nftnl_table_nlmsg_build_payload(struct nlmsghdr *nlh, const struct nftnl_ta
 		mnl_attr_put_u64(nlh, NFTA_TABLE_HANDLE, htobe64(t->handle));
 	if (t->flags & (1 << NFTNL_TABLE_FLAGS))
 		mnl_attr_put_u32(nlh, NFTA_TABLE_FLAGS, htonl(t->table_flags));
+	if (t->flags & (1 << NFTNL_TABLE_USERDATA))
+		mnl_attr_put(nlh, NFTA_TABLE_USERDATA, t->user.len, t->user.data);
 }
 
 static int nftnl_table_parse_attr_cb(const struct nlattr *attr, void *data)
@@ -240,6 +261,10 @@ static int nftnl_table_parse_attr_cb(const struct nlattr *attr, void *data)
 		if (mnl_attr_validate(attr, MNL_TYPE_U32) < 0)
 			abi_breakage();
 		break;
+	case NFTA_TABLE_USERDATA:
+		if (mnl_attr_validate(attr, MNL_TYPE_BINARY) < 0)
+			abi_breakage();
+		break;
 	}
 
 	tb[type] = attr;
@@ -251,6 +276,7 @@ int nftnl_table_nlmsg_parse(const struct nlmsghdr *nlh, struct nftnl_table *t)
 {
 	struct nlattr *tb[NFTA_TABLE_MAX+1] = {};
 	struct nfgenmsg *nfg = mnl_nlmsg_get_payload(nlh);
+	int ret;
 
 	if (mnl_attr_parse(nlh, sizeof(*nfg), nftnl_table_parse_attr_cb, tb) < 0)
 		return -1;
@@ -275,6 +301,13 @@ int nftnl_table_nlmsg_parse(const struct nlmsghdr *nlh, struct nftnl_table *t)
 		t->handle = be64toh(mnl_attr_get_u64(tb[NFTA_TABLE_HANDLE]));
 		t->flags |= (1 << NFTNL_TABLE_HANDLE);
 	}
+	if (tb[NFTA_TABLE_USERDATA]) {
+		ret = nftnl_table_set_data(t, NFTNL_TABLE_USERDATA,
+			mnl_attr_get_payload(tb[NFTA_TABLE_USERDATA]),
+			mnl_attr_get_payload_len(tb[NFTA_TABLE_USERDATA]));
+		if (ret < 0)
+			return ret;
+	}
 
 	t->family = nfg->nfgen_family;
 	t->flags |= (1 << NFTNL_TABLE_FAMILY);
-- 
2.27.0

Re: [PATCH libnftnl 2/3] table: add userdata support

[Pablo Neira Ayuso]

Applied, thanks.

[PATCH nftables 3/3] src: add comment support when adding tables

[Jose M. Guisado Gomez]

Adds userdata building logic if a comment is specified when creating a
new table. Adds netlink userdata parsing callback function.

Relies on kernel supporting userdata for nft_table.

Example:

> nft add table ip x { comment "test"\; }
> nft list ruleset

table ip x {
	comment "test"
}

Signed-off-by: Jose M. Guisado Gomez <guigom@riseup.net>
---
 include/rule.h                                |  1 +
 src/mnl.c                                     | 19 +++++++++--
 src/netlink.c                                 | 32 +++++++++++++++++++
 src/parser_bison.y                            |  4 +++
 src/rule.c                                    |  5 +++
 .../testcases/optionals/comments_table_0      |  0
 .../testcases/optionals/comments_table_1      |  0
 .../optionals/dumps/comments_table_0.nft      |  0
 .../optionals/dumps/comments_table_1.nft      |  0
 9 files changed, 59 insertions(+), 2 deletions(-)
 create mode 100755 tests/shell/testcases/optionals/comments_table_0
 create mode 100755 tests/shell/testcases/optionals/comments_table_1
 create mode 100644 tests/shell/testcases/optionals/dumps/comments_table_0.nft
 create mode 100644 tests/shell/testcases/optionals/dumps/comments_table_1.nft

diff --git a/include/rule.h b/include/rule.h
index caca63d0..1167b1fb 100644
--- a/include/rule.h
+++ b/include/rule.h
@@ -159,6 +159,7 @@ struct table {
 	struct list_head	chain_bindings;
 	enum table_flags 	flags;
 	unsigned int		refcnt;
+	const char		*comment;
 };
 
 extern struct table *table_alloc(void);
diff --git a/src/mnl.c b/src/mnl.c
index 388eff8f..3bf13991 100644
--- a/src/mnl.c
+++ b/src/mnl.c
@@ -832,22 +832,37 @@ int mnl_nft_table_add(struct netlink_ctx *ctx, struct cmd *cmd,
 {
 	struct nftnl_table *nlt;
 	struct nlmsghdr *nlh;
+	struct nftnl_udata_buf *udbuf;
 
 	nlt = nftnl_table_alloc();
 	if (nlt == NULL)
 		memory_allocation_error();
 
 	nftnl_table_set_u32(nlt, NFTNL_TABLE_FAMILY, cmd->handle.family);
-	if (cmd->table)
+	if (cmd->table) {
 		nftnl_table_set_u32(nlt, NFTNL_TABLE_FLAGS, cmd->table->flags);
-	else
+
+		if (cmd->table->comment) {
+			udbuf = nftnl_udata_buf_alloc(NFT_USERDATA_MAXLEN);
+			if (!udbuf)
+				memory_allocation_error();
+			if (!nftnl_udata_put_strz(udbuf, NFTNL_UDATA_TABLE_COMMENT, cmd->table->comment))
+				memory_allocation_error();
+			nftnl_table_set_data(nlt, NFTNL_TABLE_USERDATA, nftnl_udata_buf_data(udbuf),
+					     nftnl_udata_buf_len(udbuf));
+			nftnl_udata_buf_free(udbuf);
+		}
+	}
+	else {
 		nftnl_table_set_u32(nlt, NFTNL_TABLE_FLAGS, 0);
+	}
 
 	nlh = nftnl_nlmsg_build_hdr(nftnl_batch_buffer(ctx->batch),
 				    NFT_MSG_NEWTABLE,
 				    cmd->handle.family,
 				    flags, ctx->seqnum);
 
+
 	cmd_add_loc(cmd, nlh->nlmsg_len, &cmd->handle.table.location);
 	mnl_attr_put_strz(nlh, NFTA_TABLE_NAME, cmd->handle.table.name);
 	nftnl_table_nlmsg_build_payload(nlh, nlt);
diff --git a/src/netlink.c b/src/netlink.c
index 20b3cdf5..813f33c1 100644
--- a/src/netlink.c
+++ b/src/netlink.c
@@ -583,10 +583,32 @@ int netlink_list_chains(struct netlink_ctx *ctx, const struct handle *h)
 	return 0;
 }
 
+static int table_parse_udata_cb(const struct nftnl_udata *attr, void *data)
+{
+	unsigned char *value = nftnl_udata_get(attr);
+	const struct nftnl_udata **tb = data;
+	uint8_t type = nftnl_udata_type(attr);
+	uint8_t len = nftnl_udata_len(attr);
+
+	switch (type) {
+		case NFTNL_UDATA_TABLE_COMMENT:
+			if (value[len - 1] != '\0')
+				return -1;
+			break;
+		default:
+			return 0;
+	}
+	tb[type] = attr;
+	return 0;
+}
+
 struct table *netlink_delinearize_table(struct netlink_ctx *ctx,
 					const struct nftnl_table *nlt)
 {
 	struct table *table;
+	const struct nftnl_udata *ud[NFTNL_UDATA_TABLE_MAX + 1] = {};
+	const char *udata;
+	uint32_t ulen;
 
 	table = table_alloc();
 	table->handle.family = nftnl_table_get_u32(nlt, NFTNL_TABLE_FAMILY);
@@ -594,6 +616,16 @@ struct table *netlink_delinearize_table(struct netlink_ctx *ctx,
 	table->flags	     = nftnl_table_get_u32(nlt, NFTNL_TABLE_FLAGS);
 	table->handle.handle.id = nftnl_table_get_u64(nlt, NFTNL_TABLE_HANDLE);
 
+	if (nftnl_table_is_set(nlt, NFTNL_TABLE_USERDATA)) {
+		udata = nftnl_table_get_data(nlt, NFTNL_TABLE_USERDATA, &ulen);
+		if (nftnl_udata_parse(udata, ulen, table_parse_udata_cb, ud) < 0) {
+			netlink_io_error(ctx, NULL, "Cannot parse userdata");
+			return NULL;
+		}
+		if (ud[NFTNL_UDATA_TABLE_COMMENT])
+			table->comment = xstrdup(nftnl_udata_get(ud[NFTNL_UDATA_TABLE_COMMENT]));
+	}
+
 	return table;
 }
 
diff --git a/src/parser_bison.y b/src/parser_bison.y
index 7e094ff6..937468c1 100644
--- a/src/parser_bison.y
+++ b/src/parser_bison.y
@@ -1533,6 +1533,10 @@ table_options		:	FLAGS		STRING
 					YYERROR;
 				}
 			}
+			|	comment_spec
+			{
+				$<table>0->comment = $1;
+			}
 			;
 
 table_block		:	/* empty */	{ $$ = $<table>-1; }
diff --git a/src/rule.c b/src/rule.c
index 2b5685c2..775e05c2 100644
--- a/src/rule.c
+++ b/src/rule.c
@@ -1317,6 +1317,8 @@ void table_free(struct table *table)
 
 	if (--table->refcnt > 0)
 		return;
+	if (table->comment)
+		xfree(table->comment);
 	list_for_each_entry_safe(chain, next, &table->chains, list)
 		chain_free(chain);
 	list_for_each_entry_safe(chain, next, &table->chain_bindings, list)
@@ -1414,6 +1416,9 @@ static void table_print(const struct table *table, struct output_ctx *octx)
 	nft_print(octx, "\n");
 	table_print_options(table, &delim, octx);
 
+	if (table->comment)
+		nft_print(octx, "\tcomment \"%s\"\n", table->comment);
+
 	list_for_each_entry(obj, &table->objs, list) {
 		nft_print(octx, "%s", delim);
 		obj_print(obj, octx);
diff --git a/tests/shell/testcases/optionals/comments_table_0 b/tests/shell/testcases/optionals/comments_table_0
new file mode 100755
index 00000000..e69de29b
diff --git a/tests/shell/testcases/optionals/comments_table_1 b/tests/shell/testcases/optionals/comments_table_1
new file mode 100755
index 00000000..e69de29b
diff --git a/tests/shell/testcases/optionals/dumps/comments_table_0.nft b/tests/shell/testcases/optionals/dumps/comments_table_0.nft
new file mode 100644
index 00000000..e69de29b
diff --git a/tests/shell/testcases/optionals/dumps/comments_table_1.nft b/tests/shell/testcases/optionals/dumps/comments_table_1.nft
new file mode 100644
index 00000000..e69de29b
-- 
2.27.0

[PATCH nftables v2 3/3] src: add comment support when adding tables

[Jose M. Guisado Gomez]

Adds userdata building logic if a comment is specified when creating a
new table. Adds netlink userdata parsing callback function.

Relies on kernel supporting userdata for nft_table.

Example:

> nft add table ip x { comment "test"\; }
> nft list ruleset

table ip x {
	comment "test"
}

Signed-off-by: Jose M. Guisado Gomez <guigom@riseup.net>
---
v2 does not include empty tests file as previous patch version

 include/rule.h                                |  1 +
 src/mnl.c                                     | 18 +++++++++--
 src/netlink.c                                 | 32 +++++++++++++++++++
 src/parser_bison.y                            |  4 +++
 src/rule.c                                    |  5 +++
 .../testcases/optionals/comments_table_0      |  6 ++++
 .../optionals/dumps/comments_table_0.nft      |  3 ++
 7 files changed, 67 insertions(+), 2 deletions(-)
 create mode 100755 tests/shell/testcases/optionals/comments_table_0
 create mode 100644 tests/shell/testcases/optionals/dumps/comments_table_0.nft

diff --git a/include/rule.h b/include/rule.h
index caca63d0..1167b1fb 100644
--- a/include/rule.h
+++ b/include/rule.h
@@ -159,6 +159,7 @@ struct table {
 	struct list_head	chain_bindings;
 	enum table_flags 	flags;
 	unsigned int		refcnt;
+	const char		*comment;
 };
 
 extern struct table *table_alloc(void);
diff --git a/src/mnl.c b/src/mnl.c
index 388eff8f..c79d6c4f 100644
--- a/src/mnl.c
+++ b/src/mnl.c
@@ -832,16 +832,30 @@ int mnl_nft_table_add(struct netlink_ctx *ctx, struct cmd *cmd,
 {
 	struct nftnl_table *nlt;
 	struct nlmsghdr *nlh;
+	struct nftnl_udata_buf *udbuf;
 
 	nlt = nftnl_table_alloc();
 	if (nlt == NULL)
 		memory_allocation_error();
 
 	nftnl_table_set_u32(nlt, NFTNL_TABLE_FAMILY, cmd->handle.family);
-	if (cmd->table)
+	if (cmd->table) {
 		nftnl_table_set_u32(nlt, NFTNL_TABLE_FLAGS, cmd->table->flags);
-	else
+
+		if (cmd->table->comment) {
+			udbuf = nftnl_udata_buf_alloc(NFT_USERDATA_MAXLEN);
+			if (!udbuf)
+				memory_allocation_error();
+			if (!nftnl_udata_put_strz(udbuf, NFTNL_UDATA_TABLE_COMMENT, cmd->table->comment))
+				memory_allocation_error();
+			nftnl_table_set_data(nlt, NFTNL_TABLE_USERDATA, nftnl_udata_buf_data(udbuf),
+					     nftnl_udata_buf_len(udbuf));
+			nftnl_udata_buf_free(udbuf);
+		}
+	}
+	else {
 		nftnl_table_set_u32(nlt, NFTNL_TABLE_FLAGS, 0);
+	}
 
 	nlh = nftnl_nlmsg_build_hdr(nftnl_batch_buffer(ctx->batch),
 				    NFT_MSG_NEWTABLE,
diff --git a/src/netlink.c b/src/netlink.c
index 20b3cdf5..813f33c1 100644
--- a/src/netlink.c
+++ b/src/netlink.c
@@ -583,10 +583,32 @@ int netlink_list_chains(struct netlink_ctx *ctx, const struct handle *h)
 	return 0;
 }
 
+static int table_parse_udata_cb(const struct nftnl_udata *attr, void *data)
+{
+	unsigned char *value = nftnl_udata_get(attr);
+	const struct nftnl_udata **tb = data;
+	uint8_t type = nftnl_udata_type(attr);
+	uint8_t len = nftnl_udata_len(attr);
+
+	switch (type) {
+		case NFTNL_UDATA_TABLE_COMMENT:
+			if (value[len - 1] != '\0')
+				return -1;
+			break;
+		default:
+			return 0;
+	}
+	tb[type] = attr;
+	return 0;
+}
+
 struct table *netlink_delinearize_table(struct netlink_ctx *ctx,
 					const struct nftnl_table *nlt)
 {
 	struct table *table;
+	const struct nftnl_udata *ud[NFTNL_UDATA_TABLE_MAX + 1] = {};
+	const char *udata;
+	uint32_t ulen;
 
 	table = table_alloc();
 	table->handle.family = nftnl_table_get_u32(nlt, NFTNL_TABLE_FAMILY);
@@ -594,6 +616,16 @@ struct table *netlink_delinearize_table(struct netlink_ctx *ctx,
 	table->flags	     = nftnl_table_get_u32(nlt, NFTNL_TABLE_FLAGS);
 	table->handle.handle.id = nftnl_table_get_u64(nlt, NFTNL_TABLE_HANDLE);
 
+	if (nftnl_table_is_set(nlt, NFTNL_TABLE_USERDATA)) {
+		udata = nftnl_table_get_data(nlt, NFTNL_TABLE_USERDATA, &ulen);
+		if (nftnl_udata_parse(udata, ulen, table_parse_udata_cb, ud) < 0) {
+			netlink_io_error(ctx, NULL, "Cannot parse userdata");
+			return NULL;
+		}
+		if (ud[NFTNL_UDATA_TABLE_COMMENT])
+			table->comment = xstrdup(nftnl_udata_get(ud[NFTNL_UDATA_TABLE_COMMENT]));
+	}
+
 	return table;
 }
 
diff --git a/src/parser_bison.y b/src/parser_bison.y
index 7e094ff6..937468c1 100644
--- a/src/parser_bison.y
+++ b/src/parser_bison.y
@@ -1533,6 +1533,10 @@ table_options		:	FLAGS		STRING
 					YYERROR;
 				}
 			}
+			|	comment_spec
+			{
+				$<table>0->comment = $1;
+			}
 			;
 
 table_block		:	/* empty */	{ $$ = $<table>-1; }
diff --git a/src/rule.c b/src/rule.c
index 2b5685c2..775e05c2 100644
--- a/src/rule.c
+++ b/src/rule.c
@@ -1317,6 +1317,8 @@ void table_free(struct table *table)
 
 	if (--table->refcnt > 0)
 		return;
+	if (table->comment)
+		xfree(table->comment);
 	list_for_each_entry_safe(chain, next, &table->chains, list)
 		chain_free(chain);
 	list_for_each_entry_safe(chain, next, &table->chain_bindings, list)
@@ -1414,6 +1416,9 @@ static void table_print(const struct table *table, struct output_ctx *octx)
 	nft_print(octx, "\n");
 	table_print_options(table, &delim, octx);
 
+	if (table->comment)
+		nft_print(octx, "\tcomment \"%s\"\n", table->comment);
+
 	list_for_each_entry(obj, &table->objs, list) {
 		nft_print(octx, "%s", delim);
 		obj_print(obj, octx);
diff --git a/tests/shell/testcases/optionals/comments_table_0 b/tests/shell/testcases/optionals/comments_table_0
new file mode 100755
index 00000000..57d632e6
--- /dev/null
+++ b/tests/shell/testcases/optionals/comments_table_0
@@ -0,0 +1,6 @@
+#!/bin/bash
+
+# comments are shown
+
+$NFT add table test { comment \"test_comment\"\; }
+$NFT -a list table test | grep '\"test_comment\"' >/dev/null
diff --git a/tests/shell/testcases/optionals/dumps/comments_table_0.nft b/tests/shell/testcases/optionals/dumps/comments_table_0.nft
new file mode 100644
index 00000000..32ae3c2d
--- /dev/null
+++ b/tests/shell/testcases/optionals/dumps/comments_table_0.nft
@@ -0,0 +1,3 @@
+table ip test {
+	comment "test_comment"
+}
-- 
2.27.0

Re: [PATCH nftables v2 3/3] src: add comment support when adding tables

[Pablo Neira Ayuso]

On Fri, Aug 21, 2020 at 06:40:30PM +0200, Jose M. Guisado Gomez wrote:
> Adds userdata building logic if a comment is specified when creating a
> new table. Adds netlink userdata parsing callback function.

Applied, thanks.