diff options
author | 2020-02-25 15:04:27 -0800 | |
---|---|---|
committer | 2020-02-27 18:50:19 -0800 | |
commit | 085c20cacf2b72991ce1c9d99a5e2f1d9e73bb68 (patch) | |
tree | c46fa77ecfc97e4120c02b7a8bd517e635afc7ee /net | |
parent | bpf: INET_DIAG support in bpf_sk_storage (diff) | |
download | linux-085c20cacf2b72991ce1c9d99a5e2f1d9e73bb68.tar.gz linux-085c20cacf2b72991ce1c9d99a5e2f1d9e73bb68.tar.bz2 linux-085c20cacf2b72991ce1c9d99a5e2f1d9e73bb68.zip |
bpf: inet_diag: Dump bpf_sk_storages in inet_diag_dump()
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.
bpf_sk_storages can be added to the system at runtime. It is difficult
to find a proper static value for cb->min_dump_alloc.
This patch learns the nlattr size required to dump the bpf_sk_storages
of a sk. If it happens to be the very first nlmsg of a dump and it
cannot fit the needed bpf_sk_storages, it will try to expand the
skb by "pskb_expand_head()".
Instead of expanding it in inet_sk_diag_fill(), it is expanded at a
sleepable context in __inet_diag_dump() so __GFP_DIRECT_RECLAIM can
be used. In __inet_diag_dump(), it will retry as long as the
skb is empty and the cb->min_dump_alloc becomes larger than before.
cb->min_dump_alloc is bounded by KMALLOC_MAX_SIZE. The min_dump_alloc
is also changed from 'u16' to 'u32' to accommodate a sk that may have
a few large bpf_sk_storages.
The updated cb->min_dump_alloc will also be used to allocate the skb in
the next dump. This logic already exists in netlink_dump().
Here is the sample output of a locally modified 'ss' and it could be made
more readable by using BTF later:
[root@arch-fb-vm1 ~]# ss --bpf-map-id 14 --bpf-map-id 13 -t6an 'dst [::1]:8989'
State Recv-Q Send-Q Local Address:Port Peer Address:PortProcess
ESTAB 0 0 [::1]:51072 [::1]:8989
bpf_map_id:14 value:[ 3feb ]
bpf_map_id:13 value:[ 3f ]
ESTAB 0 0 [::1]:51070 [::1]:8989
bpf_map_id:14 value:[ 3feb ]
bpf_map_id:13 value:[ 3f ]
[root@arch-fb-vm1 ~]# ~/devshare/github/iproute2/misc/ss --bpf-maps -t6an 'dst [::1]:8989'
State Recv-Q Send-Q Local Address:Port Peer Address:Port Process
ESTAB 0 0 [::1]:51072 [::1]:8989
bpf_map_id:14 value:[ 3feb ]
bpf_map_id:13 value:[ 3f ]
bpf_map_id:12 value:[ 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000... total:65407 ]
ESTAB 0 0 [::1]:51070 [::1]:8989
bpf_map_id:14 value:[ 3feb ]
bpf_map_id:13 value:[ 3f ]
bpf_map_id:12 value:[ 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000... total:65407 ]
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20200225230427.1976129-1-kafai@fb.com
Diffstat (limited to 'net')
-rw-r--r-- | net/ipv4/inet_diag.c | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/net/ipv4/inet_diag.c b/net/ipv4/inet_diag.c index 4bce8a477699..e1cad25909df 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 @@ errout: } 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 +1081,15 @@ static int __inet_diag_dump(struct sk_buff *skb, struct netlink_callback *cb, err = PTR_ERR(handler); inet_diag_unlock_handler(handler); + /* The skb is not large enough to fit one sk info and + * inet_sk_diag_fill() has requested for a larger skb. + */ + if (!skb->len && cb->min_dump_alloc > prev_min_dump_alloc) { + err = pskb_expand_head(skb, 0, cb->min_dump_alloc, GFP_KERNEL); + if (!err) + goto again; + } + return err ? : skb->len; } @@ -1068,6 +1127,18 @@ 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 +1155,9 @@ 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; |