[bpf-next,v2,11/20] bpf: add task and task/file iterator targets

Message ID	20200504062559.2048228-1-yhs@fb.com
State	New
Headers	show Return-Path: <SRS0=PKgQ=6S=vger.kernel.org=netdev-owner@kernel.org> Smtp-Origin-Hostprefix: devbig From: Yonghong Song <yhs@fb.com> Smtp-Origin-Hostname: devbig003.ftw2.facebook.com To: Andrii Nakryiko <andriin@fb.com>, <bpf@vger.kernel.org>, Martin KaFai Lau <kafai@fb.com>, <netdev@vger.kernel.org> CC: Alexei Starovoitov <ast@fb.com>, Daniel Borkmann <daniel@iogearbox.net>, <kernel-team@fb.com> Smtp-Origin-Cluster: ftw2c04 Subject: [PATCH bpf-next v2 11/20] bpf: add task and task/file iterator targets Date: Sun, 3 May 2020 23:25:59 -0700 Message-ID: <20200504062559.2048228-1-yhs@fb.com> In-Reply-To: <20200504062547.2047304-1-yhs@fb.com> References: <20200504062547.2047304-1-yhs@fb.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain Sender: netdev-owner@vger.kernel.org Precedence: bulk
Series	[bpf-next,v2,01/20] bpf: implement an interface to register bpf_iter targets \| expand [bpf-next,v2,01/20] bpf: implement an interface to register bpf_iter targets [bpf-next,v2,03/20] bpf: support bpf tracing/iter programs for BPF_LINK_CREATE [bpf-next,v2,07/20] bpf: create file bpf iterator [bpf-next,v2,08/20] bpf: implement common macros/helpers for target iterators [bpf-next,v2,09/20] bpf: add bpf_map iterator [bpf-next,v2,10/20] net: bpf: add netlink and ipv6_route bpf_iter targets [bpf-next,v2,11/20] bpf: add task and task/file iterator targets [bpf-next,v2,13/20] bpf: add bpf_seq_printf and bpf_seq_write helpers [bpf-next,v2,15/20] bpf: support variable length array in tracing programs [bpf-next,v2,20/20] tools/bpf: selftests: add bpf_iter selftests

diff --git a/kernel/bpf/Makefile b/kernel/bpf/Makefile index b2b5eefc5254..37b2d8620153 100644 --- a/kernel/bpf/Makefile +++ b/kernel/bpf/Makefile @@ -2,7 +2,7 @@ obj-y := core.o CFLAGS_core.o += $(call cc-disable-warning, override-init) -obj-$(CONFIG_BPF_SYSCALL) += syscall.o verifier.o inode.o helpers.o tnum.o bpf_iter.o map_iter.o +obj-$(CONFIG_BPF_SYSCALL) += syscall.o verifier.o inode.o helpers.o tnum.o bpf_iter.o map_iter.o task_iter.o obj-$(CONFIG_BPF_SYSCALL) += hashtab.o arraymap.o percpu_freelist.o bpf_lru_list.o lpm_trie.o map_in_map.o obj-$(CONFIG_BPF_SYSCALL) += local_storage.o queue_stack_maps.o obj-$(CONFIG_BPF_SYSCALL) += disasm.o diff --git a/kernel/bpf/task_iter.c b/kernel/bpf/task_iter.c new file mode 100644 index 000000000000..1ca258f6e9f4 --- /dev/null +++ b/kernel/bpf/task_iter.c @@ -0,0 +1,336 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* Copyright (c) 2020 Facebook */ + +#include <linux/init.h> +#include <linux/namei.h> +#include <linux/pid_namespace.h> +#include <linux/fs.h> +#include <linux/fdtable.h> +#include <linux/filter.h> + +struct bpf_iter_seq_task_common { + struct pid_namespace *ns; +}; + +struct bpf_iter_seq_task_info { + struct bpf_iter_seq_task_common common; + struct task_struct *task; + u32 id; +}; + +static struct task_struct *task_seq_get_next(struct pid_namespace *ns, u32 *id) +{ + struct task_struct *task = NULL; + struct pid *pid; + + rcu_read_lock(); + pid = idr_get_next(&ns->idr, id); + if (pid) + task = get_pid_task(pid, PIDTYPE_PID); + rcu_read_unlock(); + + return task; +} + +static void *task_seq_start(struct seq_file *seq, loff_t *pos) +{ + struct bpf_iter_seq_task_info *info = seq->private; + struct task_struct *task; + u32 id = info->id; + + task = task_seq_get_next(info->common.ns, &id); + if (!task) + return NULL; + + ++*pos; + info->task = task; + info->id = id; + + return task; +} + +static void *task_seq_next(struct seq_file *seq, void *v, loff_t *pos) +{ + struct bpf_iter_seq_task_info *info = seq->private; + struct task_struct *task; + + ++*pos; + ++info->id; + task = task_seq_get_next(info->common.ns, &info->id); + if (!task) + return NULL; + + put_task_struct(info->task); + info->task = task; + return task; +} + +struct bpf_iter__task { + __bpf_md_ptr(struct bpf_iter_meta *, meta); + __bpf_md_ptr(struct task_struct *, task); +}; + +DEFINE_BPF_ITER_FUNC(task, struct bpf_iter_meta *meta, struct task_struct *task) + +static int __task_seq_show(struct seq_file *seq, void *v, bool in_stop) +{ + struct bpf_iter_meta meta; + struct bpf_iter__task ctx; + struct bpf_prog *prog; + int ret = 0; + + meta.seq = seq; + prog = bpf_iter_get_info(&meta, in_stop); + if (prog) { + meta.seq = seq; + ctx.meta = &meta; + ctx.task = v; + ret = bpf_iter_run_prog(prog, &ctx); + } + + return 0; +} + +static int task_seq_show(struct seq_file *seq, void *v) +{ + return __task_seq_show(seq, v, false); +} + +static void task_seq_stop(struct seq_file *seq, void *v) +{ + struct bpf_iter_seq_task_info *info = seq->private; + + if (!v) + __task_seq_show(seq, v, true); + + if (info->task) { + put_task_struct(info->task); + info->task = NULL; + } +} + +static const struct seq_operations task_seq_ops = { + .start = task_seq_start, + .next = task_seq_next, + .stop = task_seq_stop, + .show = task_seq_show, +}; + +struct bpf_iter_seq_task_file_info { + struct bpf_iter_seq_task_common common; + struct task_struct *task; + struct files_struct *files; + u32 id; + u32 fd; +}; + +static struct file *task_file_seq_get_next(struct pid_namespace *ns, u32 *id, + int *fd, struct task_struct **task, + struct files_struct **fstruct) +{ + struct files_struct *files; + struct task_struct *tk; + u32 sid = *id; + int sfd; + + /* If this function returns a non-NULL file object, + * it held a reference to the files_struct and file. + * Otherwise, it does not hold any reference. + */ +again: + if (*fstruct) { + files = *fstruct; + sfd = *fd; + } else { + tk = task_seq_get_next(ns, &sid); + if (!tk) + return NULL; + + files = get_files_struct(tk); + put_task_struct(tk); + if (!files) { + sid = ++(*id); + *fd = 0; + goto again; + } + *fstruct = files; + *task = tk; + if (sid == *id) { + sfd = *fd; + } else { + *id = sid; + sfd = 0; + } + } + + rcu_read_lock(); + for (; sfd < files_fdtable(files)->max_fds; sfd++) { + struct file *f; + + f = fcheck_files(files, sfd); + if (!f) + continue; + *fd = sfd; + get_file(f); + rcu_read_unlock(); + return f; + } + + /* the current task is done, go to the next task */ + rcu_read_unlock(); + put_files_struct(files); + *fstruct = NULL; + sid = ++(*id); + *fd = 0; + goto again; +} + +static void *task_file_seq_start(struct seq_file *seq, loff_t *pos) +{ + struct bpf_iter_seq_task_file_info *info = seq->private; + struct files_struct *files = NULL; + struct task_struct *task = NULL; + struct file *file; + u32 id = info->id; + int fd = info->fd; + + file = task_file_seq_get_next(info->common.ns, &id, &fd, &task, &files); + if (!file) { + info->files = NULL; + return NULL; + } + + ++*pos; + info->id = id; + info->fd = fd; + info->task = task; + info->files = files; + + return file; +} + +static void *task_file_seq_next(struct seq_file *seq, void *v, loff_t *pos) +{ + struct bpf_iter_seq_task_file_info *info = seq->private; + struct files_struct *files = info->files; + struct task_struct *task = info->task; + struct file *file; + + ++*pos; + ++info->fd; + fput((struct file *)v); + file = task_file_seq_get_next(info->common.ns, &info->id, &info->fd, + &task, &files); + if (!file) { + info->files = NULL; + return NULL; + } + + info->task = task; + info->files = files; + + return file; +} + +struct bpf_iter__task_file { + __bpf_md_ptr(struct bpf_iter_meta *, meta); + __bpf_md_ptr(struct task_struct *, task); + u32 fd; + __bpf_md_ptr(struct file *, file); +}; + +DEFINE_BPF_ITER_FUNC(task_file, struct bpf_iter_meta *meta, + struct task_struct *task, u32 fd, + struct file *file) + +static int __task_file_seq_show(struct seq_file *seq, void *v, bool in_stop) +{ + struct bpf_iter_seq_task_file_info *info = seq->private; + struct bpf_iter__task_file ctx; + struct bpf_iter_meta meta; + struct bpf_prog *prog; + int ret = 0; + + meta.seq = seq; + prog = bpf_iter_get_info(&meta, in_stop); + if (prog) { + ctx.meta = &meta; + ctx.task = info->task; + ctx.fd = info->fd; + ctx.file = v; + ret = bpf_iter_run_prog(prog, &ctx); + } + + return ret; +} + +static int task_file_seq_show(struct seq_file *seq, void *v) +{ + return __task_file_seq_show(seq, v, false); +} + +static void task_file_seq_stop(struct seq_file *seq, void *v) +{ + struct bpf_iter_seq_task_file_info *info = seq->private; + + if (!v) + __task_file_seq_show(seq, v, true); + else if (!IS_ERR(v)) + fput((struct file *)v); + + if (info->files) { + put_files_struct(info->files); + info->files = NULL; + } +} + +/* The first field of task/task_file private data is + * struct bpf_iter_seq_task_common. + */ +static int init_seq_pidns(void *priv_data) +{ + struct bpf_iter_seq_task_common *common = priv_data; + + common->ns = get_pid_ns(task_active_pid_ns(current)); + return 0; +} + +static void fini_seq_pidns(void *priv_data) +{ + struct bpf_iter_seq_task_common *common = priv_data; + + put_pid_ns(common->ns); +} + +static const struct seq_operations task_file_seq_ops = { + .start = task_file_seq_start, + .next = task_file_seq_next, + .stop = task_file_seq_stop, + .show = task_file_seq_show, +}; + +static int __init task_iter_init(void) +{ + struct bpf_iter_reg task_file_reg_info = { + .target = "task_file", + .seq_ops = &task_file_seq_ops, + .init_seq_private = init_seq_pidns, + .fini_seq_private = fini_seq_pidns, + .seq_priv_size = sizeof(struct bpf_iter_seq_task_file_info), + }; + struct bpf_iter_reg task_reg_info = { + .target = "task", + .seq_ops = &task_seq_ops, + .init_seq_private = init_seq_pidns, + .fini_seq_private = fini_seq_pidns, + .seq_priv_size = sizeof(struct bpf_iter_seq_task_info), + }; + int ret; + + ret = bpf_iter_reg_target(&task_reg_info); + if (ret) + return ret; + + return bpf_iter_reg_target(&task_file_reg_info); +} +late_initcall(task_iter_init);

[bpf-next,v2,11/20] bpf: add task and task/file iterator targets

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Patch