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Date: Mon, 24 Feb 2020 21:47:33 -0800
From: Song Liu <song@...nel.org>
To: Martin KaFai Lau <kafai@...com>
Cc: bpf <bpf@...r.kernel.org>, Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
David Miller <davem@...emloft.net>,
Kernel Team <kernel-team@...com>,
Networking <netdev@...r.kernel.org>
Subject: Re: [PATCH bpf-next 4/4] bpf: inet_diag: Dump bpf_sk_storages in inet_diag_dump()
On Fri, Feb 21, 2020 at 10:49 AM Martin KaFai Lau <kafai@...com> wrote:
>
> This patch will dump out the bpf_sk_storages of a sk
> if the request has the INET_DIAG_REQ_SK_BPF_STORAGES nlattr.
>
> An array of SK_DIAG_BPF_STORAGE_REQ_MAP_FD can be specified in
> INET_DIAG_REQ_SK_BPF_STORAGES to select which bpf_sk_storage to dump.
> If no map_fd is specified, all bpf_sk_storages of a sk will be dumped.
[...]
> Signed-off-by: Martin KaFai Lau <kafai@...com>
> ---
> include/linux/inet_diag.h | 4 ++
> include/linux/netlink.h | 4 +-
> include/uapi/linux/inet_diag.h | 2 +
> net/ipv4/inet_diag.c | 71 ++++++++++++++++++++++++++++++++++
> 4 files changed, 79 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/inet_diag.h b/include/linux/inet_diag.h
> index 1bb94cac265f..e4ba25d63913 100644
> --- a/include/linux/inet_diag.h
> +++ b/include/linux/inet_diag.h
> @@ -38,9 +38,13 @@ struct inet_diag_handler {
> __u16 idiag_info_size;
> };
>
> +struct bpf_sk_storage_diag;
> struct inet_diag_dump_data {
> struct nlattr *req_nlas[__INET_DIAG_REQ_MAX];
> #define inet_diag_nla_bc req_nlas[INET_DIAG_REQ_BYTECODE]
> +#define inet_diag_nla_bpf_stgs req_nlas[INET_DIAG_REQ_SK_BPF_STORAGES]
> +
> + struct bpf_sk_storage_diag *bpf_stg_diag;
> };
>
> struct inet_connection_sock;
> diff --git a/include/linux/netlink.h b/include/linux/netlink.h
> index 205fa7b1f07a..788969ccbbde 100644
> --- a/include/linux/netlink.h
> +++ b/include/linux/netlink.h
> @@ -188,10 +188,10 @@ struct netlink_callback {
> struct module *module;
> struct netlink_ext_ack *extack;
> u16 family;
> - u16 min_dump_alloc;
> - bool strict_check;
> u16 answer_flags;
> + u32 min_dump_alloc;
Maybe highlight this change in the commit log?
> unsigned int prev_seq, seq;
> + bool strict_check;
> union {
> u8 ctx[48];
>
> diff --git a/include/uapi/linux/inet_diag.h b/include/uapi/linux/inet_diag.h
> index bab9a9f8da12..75dffd78363a 100644
> --- a/include/uapi/linux/inet_diag.h
> +++ b/include/uapi/linux/inet_diag.h
> @@ -64,6 +64,7 @@ struct inet_diag_req_raw {
> enum {
> INET_DIAG_REQ_NONE,
> INET_DIAG_REQ_BYTECODE,
> + INET_DIAG_REQ_SK_BPF_STORAGES,
> __INET_DIAG_REQ_MAX,
> };
>
> @@ -155,6 +156,7 @@ enum {
> INET_DIAG_CLASS_ID, /* request as INET_DIAG_TCLASS */
> INET_DIAG_MD5SIG,
> INET_DIAG_ULP_INFO,
> + INET_DIAG_SK_BPF_STORAGES,
> __INET_DIAG_MAX,
> };
>
> diff --git a/net/ipv4/inet_diag.c b/net/ipv4/inet_diag.c
> index 4bce8a477699..8ca4d54d7c5a 100644
> --- a/net/ipv4/inet_diag.c
> +++ b/net/ipv4/inet_diag.c
> @@ -23,6 +23,7 @@
> #include <net/inet_hashtables.h>
> #include <net/inet_timewait_sock.h>
> #include <net/inet6_hashtables.h>
> +#include <net/bpf_sk_storage.h>
> #include <net/netlink.h>
>
> #include <linux/inet.h>
> @@ -156,6 +157,8 @@ int inet_diag_msg_attrs_fill(struct sock *sk, struct sk_buff *skb,
> }
> EXPORT_SYMBOL_GPL(inet_diag_msg_attrs_fill);
>
> +#define MAX_DUMP_ALLOC_SIZE (KMALLOC_MAX_SIZE - SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
> +
> int inet_sk_diag_fill(struct sock *sk, struct inet_connection_sock *icsk,
> struct sk_buff *skb, struct netlink_callback *cb,
> const struct inet_diag_req_v2 *req,
> @@ -163,12 +166,14 @@ int inet_sk_diag_fill(struct sock *sk, struct inet_connection_sock *icsk,
> {
> const struct tcp_congestion_ops *ca_ops;
> const struct inet_diag_handler *handler;
> + struct inet_diag_dump_data *cb_data;
> int ext = req->idiag_ext;
> struct inet_diag_msg *r;
> struct nlmsghdr *nlh;
> struct nlattr *attr;
> void *info = NULL;
>
> + cb_data = cb->data;
> handler = inet_diag_table[req->sdiag_protocol];
> BUG_ON(!handler);
>
> @@ -302,6 +307,48 @@ int inet_sk_diag_fill(struct sock *sk, struct inet_connection_sock *icsk,
> goto errout;
> }
>
> + /* Keep it at the end for potential retry with a larger skb,
> + * or else do best-effort fitting, which is only done for the
> + * first_nlmsg.
> + */
> + if (cb_data->bpf_stg_diag) {
> + bool first_nlmsg = ((unsigned char *)nlh == skb->data);
> + unsigned int prev_min_dump_alloc;
> + unsigned int total_nla_size = 0;
> + unsigned int msg_len;
> + int err;
> +
> + msg_len = skb_tail_pointer(skb) - (unsigned char *)nlh;
> + err = bpf_sk_storage_diag_put(cb_data->bpf_stg_diag, sk, skb,
> + INET_DIAG_SK_BPF_STORAGES,
> + &total_nla_size);
> +
> + if (!err)
> + goto out;
> +
> + total_nla_size += msg_len;
> + prev_min_dump_alloc = cb->min_dump_alloc;
> + if (total_nla_size > prev_min_dump_alloc)
> + cb->min_dump_alloc = min_t(u32, total_nla_size,
> + MAX_DUMP_ALLOC_SIZE);
> +
> + if (!first_nlmsg)
> + goto errout;
> +
> + if (cb->min_dump_alloc > prev_min_dump_alloc)
> + /* Retry with pskb_expand_head() with
> + * __GFP_DIRECT_RECLAIM
> + */
> + goto errout;
> +
> + WARN_ON_ONCE(total_nla_size <= prev_min_dump_alloc);
> +
> + /* Send what we have for this sk
> + * and move on to the next sk in the following
> + * dump()
> + */
> + }
> +
> out:
> nlmsg_end(skb, nlh);
> return 0;
> @@ -1022,8 +1069,11 @@ static int __inet_diag_dump(struct sk_buff *skb, struct netlink_callback *cb,
> const struct inet_diag_req_v2 *r)
> {
> const struct inet_diag_handler *handler;
> + u32 prev_min_dump_alloc;
> int err = 0;
>
> +again:
> + prev_min_dump_alloc = cb->min_dump_alloc;
> handler = inet_diag_lock_handler(r->sdiag_protocol);
> if (!IS_ERR(handler))
> handler->dump(skb, cb, r);
> @@ -1031,6 +1081,12 @@ static int __inet_diag_dump(struct sk_buff *skb, struct netlink_callback *cb,
> err = PTR_ERR(handler);
> inet_diag_unlock_handler(handler);
>
> + if (!skb->len && cb->min_dump_alloc > prev_min_dump_alloc) {
Why do we check for !skb->len here?
> + err = pskb_expand_head(skb, 0, cb->min_dump_alloc, GFP_KERNEL);
> + if (!err)
> + goto again;
> + }
> +
> return err ? : skb->len;
> }
>
> @@ -1068,6 +1124,18 @@ static int __inet_diag_dump_start(struct netlink_callback *cb, int hdrlen)
> }
> }
>
> + nla = cb_data->inet_diag_nla_bpf_stgs;
> + if (nla) {
> + struct bpf_sk_storage_diag *bpf_stg_diag;
> +
> + bpf_stg_diag = bpf_sk_storage_diag_alloc(nla);
> + if (IS_ERR(bpf_stg_diag)) {
> + kfree(cb_data);
> + return PTR_ERR(bpf_stg_diag);
> + }
> + cb_data->bpf_stg_diag = bpf_stg_diag;
> + }
> +
> cb->data = cb_data;
> return 0;
> }
> @@ -1084,6 +1152,9 @@ static int inet_diag_dump_start_compat(struct netlink_callback *cb)
>
> static int inet_diag_dump_done(struct netlink_callback *cb)
> {
> + struct inet_diag_dump_data *cb_data = cb->data;
> +
> + bpf_sk_storage_diag_free(cb_data->bpf_stg_diag);
> kfree(cb->data);
>
> return 0;
> --
> 2.17.1
>
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