diff options
Diffstat (limited to 'kernel/bpf/task_iter.c')
| -rw-r--r-- | kernel/bpf/task_iter.c | 361 |
1 files changed, 361 insertions, 0 deletions
diff --git a/kernel/bpf/task_iter.c b/kernel/bpf/task_iter.c new file mode 100644 index 000000000..f3d3a562a --- /dev/null +++ b/kernel/bpf/task_iter.c @@ -0,0 +1,361 @@ +// 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> +#include <linux/btf_ids.h> + +struct bpf_iter_seq_task_common { + struct pid_namespace *ns; +}; + +struct bpf_iter_seq_task_info { + /* The first field must be struct bpf_iter_seq_task_common. + * this is assumed by {init, fini}_seq_pidns() callback functions. + */ + struct bpf_iter_seq_task_common common; + u32 tid; +}; + +static struct task_struct *task_seq_get_next(struct pid_namespace *ns, + u32 *tid, + bool skip_if_dup_files) +{ + struct task_struct *task = NULL; + struct pid *pid; + + rcu_read_lock(); +retry: + pid = find_ge_pid(*tid, ns); + if (pid) { + *tid = pid_nr_ns(pid, ns); + task = get_pid_task(pid, PIDTYPE_PID); + if (!task) { + ++*tid; + goto retry; + } else if (skip_if_dup_files && task->tgid != task->pid && + task->files == task->group_leader->files) { + put_task_struct(task); + task = NULL; + ++*tid; + goto retry; + } + } + 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; + + task = task_seq_get_next(info->common.ns, &info->tid, false); + if (!task) + return NULL; + + if (*pos == 0) + ++*pos; + 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->tid; + put_task_struct((struct task_struct *)v); + task = task_seq_get_next(info->common.ns, &info->tid, false); + if (!task) + return NULL; + + 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, struct task_struct *task, + bool in_stop) +{ + struct bpf_iter_meta meta; + struct bpf_iter__task ctx; + struct bpf_prog *prog; + + meta.seq = seq; + prog = bpf_iter_get_info(&meta, in_stop); + if (!prog) + return 0; + + meta.seq = seq; + ctx.meta = &meta; + ctx.task = task; + return bpf_iter_run_prog(prog, &ctx); +} + +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) +{ + if (!v) + (void)__task_seq_show(seq, v, true); + else + put_task_struct((struct task_struct *)v); +} + +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 { + /* The first field must be struct bpf_iter_seq_task_common. + * this is assumed by {init, fini}_seq_pidns() callback functions. + */ + struct bpf_iter_seq_task_common common; + struct task_struct *task; + struct files_struct *files; + u32 tid; + u32 fd; +}; + +static struct file * +task_file_seq_get_next(struct bpf_iter_seq_task_file_info *info) +{ + struct pid_namespace *ns = info->common.ns; + u32 curr_tid = info->tid, max_fds; + struct files_struct *curr_files; + struct task_struct *curr_task; + int curr_fd = info->fd; + + /* If this function returns a non-NULL file object, + * it held a reference to the task/files_struct/file. + * Otherwise, it does not hold any reference. + */ +again: + if (info->task) { + curr_task = info->task; + curr_files = info->files; + curr_fd = info->fd; + } else { + curr_task = task_seq_get_next(ns, &curr_tid, true); + if (!curr_task) { + info->task = NULL; + info->files = NULL; + info->tid = curr_tid; + return NULL; + } + + curr_files = get_files_struct(curr_task); + if (!curr_files) { + put_task_struct(curr_task); + curr_tid = curr_tid + 1; + info->fd = 0; + goto again; + } + + info->files = curr_files; + info->task = curr_task; + if (curr_tid == info->tid) { + curr_fd = info->fd; + } else { + info->tid = curr_tid; + curr_fd = 0; + } + } + + rcu_read_lock(); + max_fds = files_fdtable(curr_files)->max_fds; + for (; curr_fd < max_fds; curr_fd++) { + struct file *f; + + f = fcheck_files(curr_files, curr_fd); + if (!f) + continue; + if (!get_file_rcu(f)) + continue; + + /* set info->fd */ + info->fd = curr_fd; + rcu_read_unlock(); + return f; + } + + /* the current task is done, go to the next task */ + rcu_read_unlock(); + put_files_struct(curr_files); + put_task_struct(curr_task); + info->task = NULL; + info->files = NULL; + info->fd = 0; + curr_tid = ++(info->tid); + 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 file *file; + + info->task = NULL; + info->files = NULL; + file = task_file_seq_get_next(info); + if (file && *pos == 0) + ++*pos; + + 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; + + ++*pos; + ++info->fd; + fput((struct file *)v); + return task_file_seq_get_next(info); +} + +struct bpf_iter__task_file { + __bpf_md_ptr(struct bpf_iter_meta *, meta); + __bpf_md_ptr(struct task_struct *, task); + u32 fd __aligned(8); + __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, struct file *file, + 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; + + meta.seq = seq; + prog = bpf_iter_get_info(&meta, in_stop); + if (!prog) + return 0; + + ctx.meta = &meta; + ctx.task = info->task; + ctx.fd = info->fd; + ctx.file = file; + return bpf_iter_run_prog(prog, &ctx); +} + +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) { + (void)__task_file_seq_show(seq, v, true); + } else { + fput((struct file *)v); + put_files_struct(info->files); + put_task_struct(info->task); + info->files = NULL; + info->task = NULL; + } +} + +static int init_seq_pidns(void *priv_data, struct bpf_iter_aux_info *aux) +{ + 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, +}; + +BTF_ID_LIST(btf_task_file_ids) +BTF_ID(struct, task_struct) +BTF_ID(struct, file) + +static const struct bpf_iter_seq_info task_seq_info = { + .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), +}; + +static struct bpf_iter_reg task_reg_info = { + .target = "task", + .ctx_arg_info_size = 1, + .ctx_arg_info = { + { offsetof(struct bpf_iter__task, task), + PTR_TO_BTF_ID_OR_NULL }, + }, + .seq_info = &task_seq_info, +}; + +static const struct bpf_iter_seq_info task_file_seq_info = { + .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), +}; + +static struct bpf_iter_reg task_file_reg_info = { + .target = "task_file", + .ctx_arg_info_size = 2, + .ctx_arg_info = { + { offsetof(struct bpf_iter__task_file, task), + PTR_TO_BTF_ID_OR_NULL }, + { offsetof(struct bpf_iter__task_file, file), + PTR_TO_BTF_ID_OR_NULL }, + }, + .seq_info = &task_file_seq_info, +}; + +static int __init task_iter_init(void) +{ + int ret; + + task_reg_info.ctx_arg_info[0].btf_id = btf_task_file_ids[0]; + ret = bpf_iter_reg_target(&task_reg_info); + if (ret) + return ret; + + task_file_reg_info.ctx_arg_info[0].btf_id = btf_task_file_ids[0]; + task_file_reg_info.ctx_arg_info[1].btf_id = btf_task_file_ids[1]; + return bpf_iter_reg_target(&task_file_reg_info); +} +late_initcall(task_iter_init); |