381 lines
9.4 KiB
C
381 lines
9.4 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (c) 2020 Facebook
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* Copyright 2020 Google LLC.
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*/
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#include <linux/pid.h>
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#include <linux/sched.h>
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#include <linux/rculist.h>
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#include <linux/list.h>
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#include <linux/hash.h>
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#include <linux/types.h>
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#include <linux/spinlock.h>
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#include <linux/bpf.h>
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#include <linux/bpf_local_storage.h>
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#include <linux/filter.h>
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#include <uapi/linux/btf.h>
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#include <linux/btf_ids.h>
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#include <linux/fdtable.h>
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#include <linux/rcupdate_trace.h>
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DEFINE_BPF_STORAGE_CACHE(task_cache);
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static DEFINE_PER_CPU(int, bpf_task_storage_busy);
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static void bpf_task_storage_lock(void)
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{
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migrate_disable();
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this_cpu_inc(bpf_task_storage_busy);
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}
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static void bpf_task_storage_unlock(void)
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{
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this_cpu_dec(bpf_task_storage_busy);
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migrate_enable();
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}
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static bool bpf_task_storage_trylock(void)
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{
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migrate_disable();
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if (unlikely(this_cpu_inc_return(bpf_task_storage_busy) != 1)) {
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this_cpu_dec(bpf_task_storage_busy);
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migrate_enable();
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return false;
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}
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return true;
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}
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static struct bpf_local_storage __rcu **task_storage_ptr(void *owner)
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{
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struct task_struct *task = owner;
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return &task->bpf_storage;
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}
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static struct bpf_local_storage_data *
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task_storage_lookup(struct task_struct *task, struct bpf_map *map,
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bool cacheit_lockit)
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{
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struct bpf_local_storage *task_storage;
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struct bpf_local_storage_map *smap;
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task_storage =
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rcu_dereference_check(task->bpf_storage, bpf_rcu_lock_held());
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if (!task_storage)
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return NULL;
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smap = (struct bpf_local_storage_map *)map;
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return bpf_local_storage_lookup(task_storage, smap, cacheit_lockit);
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}
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void bpf_task_storage_free(struct task_struct *task)
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{
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struct bpf_local_storage *local_storage;
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bool free_task_storage = false;
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unsigned long flags;
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rcu_read_lock();
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local_storage = rcu_dereference(task->bpf_storage);
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if (!local_storage) {
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rcu_read_unlock();
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return;
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}
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bpf_task_storage_lock();
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raw_spin_lock_irqsave(&local_storage->lock, flags);
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free_task_storage = bpf_local_storage_unlink_nolock(local_storage);
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raw_spin_unlock_irqrestore(&local_storage->lock, flags);
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bpf_task_storage_unlock();
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rcu_read_unlock();
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if (free_task_storage)
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kfree_rcu(local_storage, rcu);
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}
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static void *bpf_pid_task_storage_lookup_elem(struct bpf_map *map, void *key)
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{
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struct bpf_local_storage_data *sdata;
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struct task_struct *task;
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unsigned int f_flags;
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struct pid *pid;
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int fd, err;
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fd = *(int *)key;
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pid = pidfd_get_pid(fd, &f_flags);
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if (IS_ERR(pid))
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return ERR_CAST(pid);
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/* We should be in an RCU read side critical section, it should be safe
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* to call pid_task.
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*/
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WARN_ON_ONCE(!rcu_read_lock_held());
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task = pid_task(pid, PIDTYPE_PID);
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if (!task) {
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err = -ENOENT;
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goto out;
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}
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bpf_task_storage_lock();
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sdata = task_storage_lookup(task, map, true);
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bpf_task_storage_unlock();
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put_pid(pid);
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return sdata ? sdata->data : NULL;
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out:
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put_pid(pid);
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return ERR_PTR(err);
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}
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static long bpf_pid_task_storage_update_elem(struct bpf_map *map, void *key,
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void *value, u64 map_flags)
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{
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struct bpf_local_storage_data *sdata;
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struct task_struct *task;
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unsigned int f_flags;
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struct pid *pid;
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int fd, err;
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fd = *(int *)key;
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pid = pidfd_get_pid(fd, &f_flags);
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if (IS_ERR(pid))
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return PTR_ERR(pid);
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/* We should be in an RCU read side critical section, it should be safe
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* to call pid_task.
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*/
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WARN_ON_ONCE(!rcu_read_lock_held());
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task = pid_task(pid, PIDTYPE_PID);
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if (!task) {
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err = -ENOENT;
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goto out;
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}
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bpf_task_storage_lock();
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sdata = bpf_local_storage_update(
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task, (struct bpf_local_storage_map *)map, value, map_flags,
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GFP_ATOMIC);
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bpf_task_storage_unlock();
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err = PTR_ERR_OR_ZERO(sdata);
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out:
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put_pid(pid);
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return err;
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}
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static int task_storage_delete(struct task_struct *task, struct bpf_map *map,
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bool nobusy)
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{
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struct bpf_local_storage_data *sdata;
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sdata = task_storage_lookup(task, map, false);
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if (!sdata)
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return -ENOENT;
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if (!nobusy)
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return -EBUSY;
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bpf_selem_unlink(SELEM(sdata), true);
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return 0;
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}
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static long bpf_pid_task_storage_delete_elem(struct bpf_map *map, void *key)
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{
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struct task_struct *task;
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unsigned int f_flags;
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struct pid *pid;
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int fd, err;
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fd = *(int *)key;
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pid = pidfd_get_pid(fd, &f_flags);
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if (IS_ERR(pid))
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return PTR_ERR(pid);
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/* We should be in an RCU read side critical section, it should be safe
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* to call pid_task.
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*/
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WARN_ON_ONCE(!rcu_read_lock_held());
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task = pid_task(pid, PIDTYPE_PID);
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if (!task) {
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err = -ENOENT;
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goto out;
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}
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bpf_task_storage_lock();
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err = task_storage_delete(task, map, true);
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bpf_task_storage_unlock();
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out:
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put_pid(pid);
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return err;
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}
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/* Called by bpf_task_storage_get*() helpers */
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static void *__bpf_task_storage_get(struct bpf_map *map,
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struct task_struct *task, void *value,
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u64 flags, gfp_t gfp_flags, bool nobusy)
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{
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struct bpf_local_storage_data *sdata;
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sdata = task_storage_lookup(task, map, nobusy);
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if (sdata)
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return sdata->data;
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/* only allocate new storage, when the task is refcounted */
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if (refcount_read(&task->usage) &&
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(flags & BPF_LOCAL_STORAGE_GET_F_CREATE) && nobusy) {
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sdata = bpf_local_storage_update(
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task, (struct bpf_local_storage_map *)map, value,
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BPF_NOEXIST, gfp_flags);
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return IS_ERR(sdata) ? NULL : sdata->data;
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}
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return NULL;
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}
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/* *gfp_flags* is a hidden argument provided by the verifier */
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BPF_CALL_5(bpf_task_storage_get_recur, struct bpf_map *, map, struct task_struct *,
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task, void *, value, u64, flags, gfp_t, gfp_flags)
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{
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bool nobusy;
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void *data;
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WARN_ON_ONCE(!bpf_rcu_lock_held());
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if (flags & ~BPF_LOCAL_STORAGE_GET_F_CREATE || !task)
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return (unsigned long)NULL;
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nobusy = bpf_task_storage_trylock();
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data = __bpf_task_storage_get(map, task, value, flags,
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gfp_flags, nobusy);
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if (nobusy)
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bpf_task_storage_unlock();
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return (unsigned long)data;
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}
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/* *gfp_flags* is a hidden argument provided by the verifier */
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BPF_CALL_5(bpf_task_storage_get, struct bpf_map *, map, struct task_struct *,
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task, void *, value, u64, flags, gfp_t, gfp_flags)
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{
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void *data;
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WARN_ON_ONCE(!bpf_rcu_lock_held());
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if (flags & ~BPF_LOCAL_STORAGE_GET_F_CREATE || !task)
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return (unsigned long)NULL;
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bpf_task_storage_lock();
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data = __bpf_task_storage_get(map, task, value, flags,
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gfp_flags, true);
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bpf_task_storage_unlock();
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return (unsigned long)data;
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}
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BPF_CALL_2(bpf_task_storage_delete_recur, struct bpf_map *, map, struct task_struct *,
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task)
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{
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bool nobusy;
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int ret;
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WARN_ON_ONCE(!bpf_rcu_lock_held());
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if (!task)
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return -EINVAL;
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nobusy = bpf_task_storage_trylock();
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/* This helper must only be called from places where the lifetime of the task
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* is guaranteed. Either by being refcounted or by being protected
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* by an RCU read-side critical section.
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*/
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ret = task_storage_delete(task, map, nobusy);
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if (nobusy)
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bpf_task_storage_unlock();
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return ret;
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}
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BPF_CALL_2(bpf_task_storage_delete, struct bpf_map *, map, struct task_struct *,
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task)
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{
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int ret;
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WARN_ON_ONCE(!bpf_rcu_lock_held());
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if (!task)
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return -EINVAL;
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bpf_task_storage_lock();
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/* This helper must only be called from places where the lifetime of the task
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* is guaranteed. Either by being refcounted or by being protected
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* by an RCU read-side critical section.
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*/
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ret = task_storage_delete(task, map, true);
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bpf_task_storage_unlock();
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return ret;
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}
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static int notsupp_get_next_key(struct bpf_map *map, void *key, void *next_key)
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{
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return -ENOTSUPP;
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}
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static struct bpf_map *task_storage_map_alloc(union bpf_attr *attr)
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{
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return bpf_local_storage_map_alloc(attr, &task_cache);
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}
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static void task_storage_map_free(struct bpf_map *map)
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{
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bpf_local_storage_map_free(map, &task_cache, &bpf_task_storage_busy);
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}
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BTF_ID_LIST_GLOBAL_SINGLE(bpf_local_storage_map_btf_id, struct, bpf_local_storage_map)
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const struct bpf_map_ops task_storage_map_ops = {
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.map_meta_equal = bpf_map_meta_equal,
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.map_alloc_check = bpf_local_storage_map_alloc_check,
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.map_alloc = task_storage_map_alloc,
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.map_free = task_storage_map_free,
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.map_get_next_key = notsupp_get_next_key,
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.map_lookup_elem = bpf_pid_task_storage_lookup_elem,
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.map_update_elem = bpf_pid_task_storage_update_elem,
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.map_delete_elem = bpf_pid_task_storage_delete_elem,
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.map_check_btf = bpf_local_storage_map_check_btf,
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.map_btf_id = &bpf_local_storage_map_btf_id[0],
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.map_owner_storage_ptr = task_storage_ptr,
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};
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const struct bpf_func_proto bpf_task_storage_get_recur_proto = {
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.func = bpf_task_storage_get_recur,
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.gpl_only = false,
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.ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
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.arg1_type = ARG_CONST_MAP_PTR,
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.arg2_type = ARG_PTR_TO_BTF_ID,
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.arg2_btf_id = &btf_tracing_ids[BTF_TRACING_TYPE_TASK],
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.arg3_type = ARG_PTR_TO_MAP_VALUE_OR_NULL,
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.arg4_type = ARG_ANYTHING,
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};
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const struct bpf_func_proto bpf_task_storage_get_proto = {
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.func = bpf_task_storage_get,
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.gpl_only = false,
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.ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
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.arg1_type = ARG_CONST_MAP_PTR,
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.arg2_type = ARG_PTR_TO_BTF_ID,
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.arg2_btf_id = &btf_tracing_ids[BTF_TRACING_TYPE_TASK],
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.arg3_type = ARG_PTR_TO_MAP_VALUE_OR_NULL,
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.arg4_type = ARG_ANYTHING,
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};
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const struct bpf_func_proto bpf_task_storage_delete_recur_proto = {
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.func = bpf_task_storage_delete_recur,
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.gpl_only = false,
|
||
|
|
.ret_type = RET_INTEGER,
|
||
|
|
.arg1_type = ARG_CONST_MAP_PTR,
|
||
|
|
.arg2_type = ARG_PTR_TO_BTF_ID,
|
||
|
|
.arg2_btf_id = &btf_tracing_ids[BTF_TRACING_TYPE_TASK],
|
||
|
|
};
|
||
|
|
|
||
|
|
const struct bpf_func_proto bpf_task_storage_delete_proto = {
|
||
|
|
.func = bpf_task_storage_delete,
|
||
|
|
.gpl_only = false,
|
||
|
|
.ret_type = RET_INTEGER,
|
||
|
|
.arg1_type = ARG_CONST_MAP_PTR,
|
||
|
|
.arg2_type = ARG_PTR_TO_BTF_ID,
|
||
|
|
.arg2_btf_id = &btf_tracing_ids[BTF_TRACING_TYPE_TASK],
|
||
|
|
};
|