From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: Yonghong Song <yhs@fb.com>
Cc: Andrii Nakryiko <andriin@fb.com>, bpf <bpf@vger.kernel.org>,
Martin KaFai Lau <kafai@fb.com>,
Networking <netdev@vger.kernel.org>,
Alexei Starovoitov <ast@fb.com>,
Daniel Borkmann <daniel@iogearbox.net>,
Kernel Team <kernel-team@fb.com>
Subject: Re: [PATCH bpf-next v1 07/19] bpf: create anonymous bpf iterator
Date: Tue, 28 Apr 2020 23:56:13 -0700 [thread overview]
Message-ID: <CAEf4BzYtxOrzSW6Yy+0ABbm0Q71dkZTGDOcGCgHCVT=4ty5k1g@mail.gmail.com> (raw)
In-Reply-To: <20200427201242.2995160-1-yhs@fb.com>
On Mon, Apr 27, 2020 at 1:19 PM Yonghong Song <yhs@fb.com> wrote:
>
> A new bpf command BPF_ITER_CREATE is added.
>
> The anonymous bpf iterator is seq_file based.
> The seq_file private data are referenced by targets.
> The bpf_iter infrastructure allocated additional space
> at seq_file->private after the space used by targets
> to store some meta data, e.g.,
> prog: prog to run
> session_id: an unique id for each opened seq_file
> seq_num: how many times bpf programs are queried in this session
> has_last: indicate whether or not bpf_prog has been called after
> all valid objects have been processed
>
> A map between file and prog/link is established to help
> fops->release(). When fops->release() is called, just based on
> inode and file, bpf program cannot be located since target
> seq_priv_size not available. This map helps retrieve the prog
> whose reference count needs to be decremented.
>
> Signed-off-by: Yonghong Song <yhs@fb.com>
> ---
> include/linux/bpf.h | 3 +
> include/uapi/linux/bpf.h | 6 ++
> kernel/bpf/bpf_iter.c | 162 ++++++++++++++++++++++++++++++++-
> kernel/bpf/syscall.c | 27 ++++++
> tools/include/uapi/linux/bpf.h | 6 ++
> 5 files changed, 203 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> index 4fc39d9b5cd0..0f0cafc65a04 100644
> --- a/include/linux/bpf.h
> +++ b/include/linux/bpf.h
> @@ -1112,6 +1112,8 @@ struct bpf_link *bpf_link_get_from_fd(u32 ufd);
> int bpf_obj_pin_user(u32 ufd, const char __user *pathname);
> int bpf_obj_get_user(const char __user *pathname, int flags);
>
> +#define BPF_DUMP_SEQ_NET_PRIVATE BIT(0)
> +
> struct bpf_iter_reg {
> const char *target;
> const char *target_func_name;
> @@ -1133,6 +1135,7 @@ int bpf_iter_run_prog(struct bpf_prog *prog, void *ctx);
> int bpf_iter_link_attach(const union bpf_attr *attr, struct bpf_prog *prog);
> int bpf_iter_link_replace(struct bpf_link *link, struct bpf_prog *old_prog,
> struct bpf_prog *new_prog);
> +int bpf_iter_new_fd(struct bpf_link *link);
>
> int bpf_percpu_hash_copy(struct bpf_map *map, void *key, void *value);
> int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value);
> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
> index f39b9fec37ab..576651110d16 100644
> --- a/include/uapi/linux/bpf.h
> +++ b/include/uapi/linux/bpf.h
> @@ -113,6 +113,7 @@ enum bpf_cmd {
> BPF_MAP_DELETE_BATCH,
> BPF_LINK_CREATE,
> BPF_LINK_UPDATE,
> + BPF_ITER_CREATE,
> };
>
> enum bpf_map_type {
> @@ -590,6 +591,11 @@ union bpf_attr {
> __u32 old_prog_fd;
> } link_update;
>
> + struct { /* struct used by BPF_ITER_CREATE command */
> + __u32 link_fd;
> + __u32 flags;
> + } iter_create;
> +
> } __attribute__((aligned(8)));
>
> /* The description below is an attempt at providing documentation to eBPF
> diff --git a/kernel/bpf/bpf_iter.c b/kernel/bpf/bpf_iter.c
> index fc1ce5ee5c3f..1f4e778d1814 100644
> --- a/kernel/bpf/bpf_iter.c
> +++ b/kernel/bpf/bpf_iter.c
> @@ -2,6 +2,7 @@
> /* Copyright (c) 2020 Facebook */
>
> #include <linux/fs.h>
> +#include <linux/anon_inodes.h>
> #include <linux/filter.h>
> #include <linux/bpf.h>
>
> @@ -19,6 +20,19 @@ struct bpf_iter_link {
> struct bpf_iter_target_info *tinfo;
> };
>
> +struct extra_priv_data {
> + struct bpf_prog *prog;
> + u64 session_id;
> + u64 seq_num;
> + bool has_last;
> +};
> +
> +struct anon_file_prog_assoc {
> + struct list_head list;
> + struct file *file;
> + struct bpf_prog *prog;
> +};
> +
> static struct list_head targets;
> static struct mutex targets_mutex;
> static bool bpf_iter_inited = false;
> @@ -26,6 +40,50 @@ static bool bpf_iter_inited = false;
> /* protect bpf_iter_link.link->prog upddate */
> static struct mutex bpf_iter_mutex;
>
> +/* Since at anon seq_file release function, the prog cannot
> + * be retrieved since target seq_priv_size is not available.
> + * Keep a list of <anon_file, prog> mapping, so that
> + * at file release stage, the prog can be released properly.
> + */
> +static struct list_head anon_iter_info;
> +static struct mutex anon_iter_info_mutex;
> +
> +/* incremented on every opened seq_file */
> +static atomic64_t session_id;
> +
> +static u32 get_total_priv_dsize(u32 old_size)
> +{
> + return roundup(old_size, 8) + sizeof(struct extra_priv_data);
> +}
> +
> +static void *get_extra_priv_dptr(void *old_ptr, u32 old_size)
> +{
> + return old_ptr + roundup(old_size, 8);
> +}
> +
> +static int anon_iter_release(struct inode *inode, struct file *file)
> +{
> + struct anon_file_prog_assoc *finfo;
> +
> + mutex_lock(&anon_iter_info_mutex);
> + list_for_each_entry(finfo, &anon_iter_info, list) {
> + if (finfo->file == file) {
I'll look at this and other patches more thoroughly tomorrow with
clear head, but this iteration to find anon_file_prog_assoc is really
unfortunate.
I think the problem is that you are allowing seq_file infrastructure
to call directly into target implementation of seq_operations without
intercepting them. If you change that and put whatever extra info is
necessary into seq_file->private in front of target's private state,
then you shouldn't need this, right?
This would also make each target's logic a bit simpler because you can:
- centralize creation and initialization of bpf_iter_meta (session_id,
seq, seq_num will be set up once in this generic code);
- loff_t pos increments;
- you can extract and centralize bpf_iter_get_prog() call in show()
implementation as well.
I think with that each target's logic will be simpler and you won't
need to maintain anon_file_prog_assocs.
Are there complications I'm missing?
[...]
next prev parent reply other threads:[~2020-04-29 6:56 UTC|newest]
Thread overview: 81+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-27 20:12 [PATCH bpf-next v1 00/19] bpf: implement bpf iterator for kernel data Yonghong Song
2020-04-27 20:12 ` [PATCH bpf-next v1 01/19] net: refactor net assignment for seq_net_private structure Yonghong Song
2020-04-29 5:38 ` Andrii Nakryiko
2020-04-27 20:12 ` [PATCH bpf-next v1 02/19] bpf: implement an interface to register bpf_iter targets Yonghong Song
2020-04-28 16:20 ` Martin KaFai Lau
2020-04-28 16:50 ` Yonghong Song
2020-04-27 20:12 ` [PATCH bpf-next v1 03/19] bpf: add bpf_map iterator Yonghong Song
2020-04-29 0:37 ` Martin KaFai Lau
2020-04-29 0:48 ` Alexei Starovoitov
2020-04-29 1:15 ` Yonghong Song
2020-04-29 2:44 ` Alexei Starovoitov
2020-04-29 5:09 ` Yonghong Song
2020-04-29 6:08 ` Andrii Nakryiko
2020-04-29 6:20 ` Yonghong Song
2020-04-29 6:30 ` Alexei Starovoitov
2020-04-29 6:40 ` Andrii Nakryiko
2020-04-29 6:44 ` Yonghong Song
2020-04-29 15:34 ` Alexei Starovoitov
2020-04-29 18:14 ` Yonghong Song
2020-04-29 19:19 ` Andrii Nakryiko
2020-04-29 20:15 ` Yonghong Song
2020-04-30 3:06 ` Alexei Starovoitov
2020-04-30 4:01 ` Yonghong Song
2020-04-29 6:34 ` Martin KaFai Lau
2020-04-29 6:51 ` Yonghong Song
2020-04-29 19:25 ` Andrii Nakryiko
2020-04-29 1:02 ` Yonghong Song
2020-04-29 6:04 ` Andrii Nakryiko
2020-04-27 20:12 ` [PATCH bpf-next v1 04/19] bpf: allow loading of a bpf_iter program Yonghong Song
2020-04-29 0:54 ` Martin KaFai Lau
2020-04-29 1:27 ` Yonghong Song
2020-04-27 20:12 ` [PATCH bpf-next v1 05/19] bpf: support bpf tracing/iter programs for BPF_LINK_CREATE Yonghong Song
2020-04-29 1:17 ` [Potential Spoof] " Martin KaFai Lau
2020-04-29 6:25 ` Andrii Nakryiko
2020-04-27 20:12 ` [PATCH bpf-next v1 06/19] bpf: support bpf tracing/iter programs for BPF_LINK_UPDATE Yonghong Song
2020-04-29 1:32 ` Martin KaFai Lau
2020-04-29 5:04 ` Yonghong Song
2020-04-29 5:58 ` Martin KaFai Lau
2020-04-29 6:32 ` Andrii Nakryiko
2020-04-29 6:41 ` Martin KaFai Lau
2020-04-27 20:12 ` [PATCH bpf-next v1 07/19] bpf: create anonymous bpf iterator Yonghong Song
2020-04-29 5:39 ` Martin KaFai Lau
2020-04-29 6:56 ` Andrii Nakryiko [this message]
2020-04-29 7:06 ` Yonghong Song
2020-04-29 18:16 ` Andrii Nakryiko
2020-04-29 18:46 ` Martin KaFai Lau
2020-04-29 19:20 ` Yonghong Song
2020-04-29 20:50 ` Martin KaFai Lau
2020-04-29 20:54 ` Yonghong Song
2020-04-29 19:39 ` Andrii Nakryiko
2020-04-27 20:12 ` [PATCH bpf-next v1 08/19] bpf: create file " Yonghong Song
2020-04-29 20:40 ` Andrii Nakryiko
2020-04-30 18:02 ` Yonghong Song
2020-04-27 20:12 ` [PATCH bpf-next v1 09/19] bpf: add PTR_TO_BTF_ID_OR_NULL support Yonghong Song
2020-04-29 20:46 ` Andrii Nakryiko
2020-04-29 20:51 ` Yonghong Song
2020-04-27 20:12 ` [PATCH bpf-next v1 10/19] bpf: add netlink and ipv6_route targets Yonghong Song
2020-04-28 19:49 ` kbuild test robot
2020-04-28 19:50 ` [RFC PATCH] bpf: __bpf_iter__netlink() can be static kbuild test robot
2020-04-27 20:12 ` [PATCH bpf-next v1 11/19] bpf: add task and task/file targets Yonghong Song
2020-04-30 2:08 ` Andrii Nakryiko
2020-05-01 17:23 ` Yonghong Song
2020-05-01 19:01 ` Andrii Nakryiko
2020-04-27 20:12 ` [PATCH bpf-next v1 12/19] bpf: add bpf_seq_printf and bpf_seq_write helpers Yonghong Song
2020-04-28 6:02 ` kbuild test robot
2020-04-28 16:35 ` Yonghong Song
2020-04-30 20:06 ` Andrii Nakryiko
2020-04-27 20:12 ` [PATCH bpf-next v1 13/19] bpf: handle spilled PTR_TO_BTF_ID properly when checking stack_boundary Yonghong Song
2020-04-27 20:12 ` [PATCH bpf-next v1 14/19] bpf: support variable length array in tracing programs Yonghong Song
2020-04-30 20:04 ` Andrii Nakryiko
2020-04-27 20:12 ` [PATCH bpf-next v1 15/19] tools/libbpf: add bpf_iter support Yonghong Song
2020-04-30 1:41 ` Andrii Nakryiko
2020-05-02 7:17 ` Yonghong Song
2020-04-27 20:12 ` [PATCH bpf-next v1 16/19] tools/bpftool: add bpf_iter support for bptool Yonghong Song
2020-04-28 9:27 ` Quentin Monnet
2020-04-28 17:35 ` Yonghong Song
2020-04-29 8:37 ` Quentin Monnet
2020-04-27 20:12 ` [PATCH bpf-next v1 17/19] tools/bpf: selftests: add iterator programs for ipv6_route and netlink Yonghong Song
2020-04-30 2:12 ` Andrii Nakryiko
2020-04-27 20:12 ` [PATCH bpf-next v1 18/19] tools/bpf: selftests: add iter progs for bpf_map/task/task_file Yonghong Song
2020-04-27 20:12 ` [PATCH bpf-next v1 19/19] tools/bpf: selftests: add bpf_iter selftests Yonghong Song
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