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  1. 28 Feb, 2020 6 commits
    • Alexei Starovoitov's avatar
      Merge branch 'bpf_sk_storage_via_inet_diag' · 812285fa
      Alexei Starovoitov authored 
      Martin KaFai Lau says:

====================
The bpf_prog can store specific info to a sk by using bpf_sk_storage.
In other words, a sk can be extended by a bpf_prog.

This series is to support providing bpf_sk_storage data during inet_diag's
dump.  The primary target is the usage like iproute2's "ss".

The first two patches are refactoring works in inet_diag to make
adding bpf_sk_storage support easier.  The next two patches do
the actual work.

Please see individual patch for details.

v2:
- Add commit message for u16 to u32 change in min_dump_alloc in Patch 4 (Song)
- Add comment to explain the !skb->len check in __inet_diag_dump in Patch 4.
- Do the map->map_type check earlier in Patch 3 for readability.
====================
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
      812285fa
    • Martin KaFai Lau's avatar
      bpf: inet_diag: Dump bpf_sk_storages in inet_diag_dump() · 085c20ca
      Martin KaFai Lau authored 
      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: default avatarMartin KaFai Lau <kafai@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarSong Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20200225230427.1976129-1-kafai@fb.com
      085c20ca
    • Martin KaFai Lau's avatar
      bpf: INET_DIAG support in bpf_sk_storage · 1ed4d924
      Martin KaFai Lau authored 
      This patch adds INET_DIAG support to bpf_sk_storage.

1. Although this series adds bpf_sk_storage diag capability to inet sk,
   bpf_sk_storage is in general applicable to all fullsock.  Hence, the
   bpf_sk_storage logic will operate on SK_DIAG_* nlattr.  The caller
   will pass in its specific nesting nlattr (e.g. INET_DIAG_*) as
   the argument.

2. The request will be like:
	INET_DIAG_REQ_SK_BPF_STORAGES (nla_nest) (defined in latter patch)
		SK_DIAG_BPF_STORAGE_REQ_MAP_FD (nla_put_u32)
		SK_DIAG_BPF_STORAGE_REQ_MAP_FD (nla_put_u32)
		......

   Considering there could have multiple bpf_sk_storages in a sk,
   instead of reusing INET_DIAG_INFO ("ss -i"),  the user can select
   some specific bpf_sk_storage to dump by specifying an array of
   SK_DIAG_BPF_STORAGE_REQ_MAP_FD.

   If no SK_DIAG_BPF_STORAGE_REQ_MAP_FD is specified (i.e. an empty
   INET_DIAG_REQ_SK_BPF_STORAGES), it will dump all bpf_sk_storages
   of a sk.

3. The reply will be like:
	INET_DIAG_BPF_SK_STORAGES (nla_nest) (defined in latter patch)
		SK_DIAG_BPF_STORAGE (nla_nest)
			SK_DIAG_BPF_STORAGE_MAP_ID (nla_put_u32)
			SK_DIAG_BPF_STORAGE_MAP_VALUE (nla_reserve_64bit)
		SK_DIAG_BPF_STORAGE (nla_nest)
			SK_DIAG_BPF_STORAGE_MAP_ID (nla_put_u32)
			SK_DIAG_BPF_STORAGE_MAP_VALUE (nla_reserve_64bit)
		......

4. Unlike other INET_DIAG info of a sk which is pretty static, the size
   required to dump the bpf_sk_storage(s) of a sk is dynamic as the
   system adding more bpf_sk_storage_map.  It is hard to set a static
   min_dump_alloc size.

   Hence, this series learns it at the runtime and adjust the
   cb->min_dump_alloc as it iterates all sk(s) of a system.  The
   "unsigned int *res_diag_size" in bpf_sk_storage_diag_put()
   is for this purpose.

   The next patch will update the cb->min_dump_alloc as it
   iterates the sk(s).
Signed-off-by: default avatarMartin KaFai Lau <kafai@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarSong Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20200225230421.1975729-1-kafai@fb.com
      1ed4d924
    • Martin KaFai Lau's avatar
      inet_diag: Move the INET_DIAG_REQ_BYTECODE nlattr to cb->data · 0df6d328
      Martin KaFai Lau authored 
      The INET_DIAG_REQ_BYTECODE nlattr is currently re-found every time when
the "dump()" is re-started.

In a latter patch, it will also need to parse the new
INET_DIAG_REQ_SK_BPF_STORAGES nlattr to learn the map_fds. Thus, this
patch takes this chance to store the parsed nlattr in cb->data
during the "start" time of a dump.

By doing this, the "bc" argument also becomes unnecessary
and is removed.  Also, the two copies of the INET_DIAG_REQ_BYTECODE
parsing-audit logic between compat/current version can be
consolidated to one.
Signed-off-by: default avatarMartin KaFai Lau <kafai@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarSong Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20200225230415.1975555-1-kafai@fb.com
      0df6d328
    • Martin KaFai Lau's avatar
      inet_diag: Refactor inet_sk_diag_fill(), dump(), and dump_one() · 5682d393
      Martin KaFai Lau authored 
      In a latter patch, there is a need to update "cb->min_dump_alloc"
in inet_sk_diag_fill() as it learns the diffierent bpf_sk_storages
stored in a sk while dumping all sk(s) (e.g. tcp_hashinfo).

The inet_sk_diag_fill() currently does not take the "cb" as an argument.
One of the reason is inet_sk_diag_fill() is used by both dump_one()
and dump() (which belong to the "struct inet_diag_handler".  The dump_one()
interface does not pass the "cb" along.

This patch is to make dump_one() pass a "cb".  The "cb" is created in
inet_diag_cmd_exact().  The "nlh" and "in_skb" are stored in "cb" as
the dump() interface does.  The total number of args in
inet_sk_diag_fill() is also cut from 10 to 7 and
that helps many callers to pass fewer args.

In particular,
"struct user_namespace *user_ns", "u32 pid", and "u32 seq"
can be replaced by accessing "cb->nlh" and "cb->skb".

A similar argument reduction is also made to
inet_twsk_diag_fill() and inet_req_diag_fill().

inet_csk_diag_dump() and inet_csk_diag_fill() are also removed.
They are mostly equivalent to inet_sk_diag_fill().  Their repeated
usages are very limited.  Thus, inet_sk_diag_fill() is directly used
in those occasions.
Signed-off-by: default avatarMartin KaFai Lau <kafai@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarSong Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20200225230409.1975173-1-kafai@fb.com
      5682d393
    • Gustavo A. R. Silva's avatar
      bpf: Replace zero-length array with flexible-array member · d7f10df8
      Gustavo A. R. Silva authored 
      The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by
this change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 76497732 ("cxgb3/l2t: Fix undefined behaviour")
Signed-off-by: default avatarGustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarSong Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20200227001744.GA3317@embeddedor
      d7f10df8
  3. 26 Feb, 2020 8 commits
  5. 25 Feb, 2020 26 commits
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