// SPDX-License-Identifier: GPL-2.0/* * Copyright (c) 2020 Facebook * Copyright 2020 Google LLC. */ #include <linux/pid.h>#include <linux/sched.h>#include <linux/rculist.h>#include <linux/list.h>#include <linux/hash.h>#include <linux/types.h>#include <linux/spinlock.h>#include <linux/bpf.h>#include <linux/bpf_local_storage.h>#include <linux/filter.h>#include <uapi/linux/btf.h>#include <linux/btf_ids.h>#include <linux/fdtable.h> DEFINE_BPF_STORAGE_CACHE(task_cache); static DEFINE_PER_CPU(int, bpf_task_storage_busy); static void bpf_task_storage_lock(void){	migrate_disable();	__this_cpu_inc(bpf_task_storage_busy);} static void bpf_task_storage_unlock(void){	__this_cpu_dec(bpf_task_storage_busy);	migrate_enable();} static bool bpf_task_storage_trylock(void){	migrate_disable();	if (unlikely(__this_cpu_inc_return(bpf_task_storage_busy) != 1)) {		__this_cpu_dec(bpf_task_storage_busy);		migrate_enable();		return false;	}	return true;} static struct bpf_local_storage __rcu **task_storage_ptr(void *owner){	struct task_struct *task = owner; 	return &task->bpf_storage;} static struct bpf_local_storage_data *task_storage_lookup(struct task_struct *task, struct bpf_map *map,		    bool cacheit_lockit){	struct bpf_local_storage *task_storage;	struct bpf_local_storage_map *smap; 	task_storage = rcu_dereference(task->bpf_storage);	if (!task_storage)		return NULL; 	smap = (struct bpf_local_storage_map *)map;	return bpf_local_storage_lookup(task_storage, smap, cacheit_lockit);} void bpf_task_storage_free(struct task_struct *task){	struct bpf_local_storage_elem *selem;	struct bpf_local_storage *local_storage;	bool free_task_storage = false;	struct hlist_node *n;	unsigned long flags; 	rcu_read_lock(); 	local_storage = rcu_dereference(task->bpf_storage);	if (!local_storage) {		rcu_read_unlock();		return;	} 	/* Neither the bpf_prog nor the bpf-map's syscall	 * could be modifying the local_storage->list now.	 * Thus, no elem can be added-to or deleted-from the	 * local_storage->list by the bpf_prog or by the bpf-map's syscall.	 *	 * It is racing with bpf_local_storage_map_free() alone	 * when unlinking elem from the local_storage->list and	 * the map's bucket->list.	 */	bpf_task_storage_lock();	raw_spin_lock_irqsave(&local_storage->lock, flags);	hlist_for_each_entry_safe(selem, n, &local_storage->list, snode) {		/* Always unlink from map before unlinking from		 * local_storage.		 */		bpf_selem_unlink_map(selem);		free_task_storage = bpf_selem_unlink_storage_nolock(			local_storage, selem, false);	}	raw_spin_unlock_irqrestore(&local_storage->lock, flags);	bpf_task_storage_unlock();	rcu_read_unlock(); 	/* free_task_storage should always be true as long as	 * local_storage->list was non-empty.	 */	if (free_task_storage)		kfree_rcu(local_storage, rcu);} static void *bpf_pid_task_storage_lookup_elem(struct bpf_map *map, void *key){	struct bpf_local_storage_data *sdata;	struct task_struct *task;	unsigned int f_flags;	struct pid *pid;	int fd, err; 	fd = *(int *)key;	pid = pidfd_get_pid(fd, &f_flags);	if (IS_ERR(pid))		return ERR_CAST(pid); 	/* We should be in an RCU read side critical section, it should be safe	 * to call pid_task.	 */	WARN_ON_ONCE(!rcu_read_lock_held());	task = pid_task(pid, PIDTYPE_PID);	if (!task) {		err = -ENOENT;		goto out;	} 	bpf_task_storage_lock();	sdata = task_storage_lookup(task, map, true);	bpf_task_storage_unlock();	put_pid(pid);	return sdata ? sdata->data : NULL;out:	put_pid(pid);	return ERR_PTR(err);} static int bpf_pid_task_storage_update_elem(struct bpf_map *map, void *key,					    void *value, u64 map_flags){	struct bpf_local_storage_data *sdata;	struct task_struct *task;	unsigned int f_flags;	struct pid *pid;	int fd, err; 	fd = *(int *)key;	pid = pidfd_get_pid(fd, &f_flags);	if (IS_ERR(pid))		return PTR_ERR(pid); 	/* We should be in an RCU read side critical section, it should be safe	 * to call pid_task.	 */	WARN_ON_ONCE(!rcu_read_lock_held());	task = pid_task(pid, PIDTYPE_PID);	if (!task) {		err = -ENOENT;		goto out;	} 	bpf_task_storage_lock();	sdata = bpf_local_storage_update(		task, (struct bpf_local_storage_map *)map, value, map_flags);	bpf_task_storage_unlock(); 	err = PTR_ERR_OR_ZERO(sdata);out:	put_pid(pid);	return err;} static int task_storage_delete(struct task_struct *task, struct bpf_map *map){	struct bpf_local_storage_data *sdata; 	sdata = task_storage_lookup(task, map, false);	if (!sdata)		return -ENOENT; 	bpf_selem_unlink(SELEM(sdata)); 	return 0;} static int bpf_pid_task_storage_delete_elem(struct bpf_map *map, void *key){	struct task_struct *task;	unsigned int f_flags;	struct pid *pid;	int fd, err; 	fd = *(int *)key;	pid = pidfd_get_pid(fd, &f_flags);	if (IS_ERR(pid))		return PTR_ERR(pid); 	/* We should be in an RCU read side critical section, it should be safe	 * to call pid_task.	 */	WARN_ON_ONCE(!rcu_read_lock_held());	task = pid_task(pid, PIDTYPE_PID);	if (!task) {		err = -ENOENT;		goto out;	} 	bpf_task_storage_lock();	err = task_storage_delete(task, map);	bpf_task_storage_unlock();out:	put_pid(pid);	return err;} BPF_CALL_4(bpf_task_storage_get, struct bpf_map *, map, struct task_struct *,	   task, void *, value, u64, flags){	struct bpf_local_storage_data *sdata; 	if (flags & ~(BPF_LOCAL_STORAGE_GET_F_CREATE))		return (unsigned long)NULL; 	if (!task)		return (unsigned long)NULL; 	if (!bpf_task_storage_trylock())		return (unsigned long)NULL; 	sdata = task_storage_lookup(task, map, true);	if (sdata)		goto unlock; 	/* only allocate new storage, when the task is refcounted */	if (refcount_read(&task->usage) &&	    (flags & BPF_LOCAL_STORAGE_GET_F_CREATE))		sdata = bpf_local_storage_update(			task, (struct bpf_local_storage_map *)map, value,			BPF_NOEXIST); unlock:	bpf_task_storage_unlock();	return IS_ERR_OR_NULL(sdata) ? (unsigned long)NULL :		(unsigned long)sdata->data;} BPF_CALL_2(bpf_task_storage_delete, struct bpf_map *, map, struct task_struct *,	   task){	int ret; 	if (!task)		return -EINVAL; 	if (!bpf_task_storage_trylock())		return -EBUSY; 	/* This helper must only be called from places where the lifetime of the task	 * is guaranteed. Either by being refcounted or by being protected	 * by an RCU read-side critical section.	 */	ret = task_storage_delete(task, map);	bpf_task_storage_unlock();	return ret;} static int notsupp_get_next_key(struct bpf_map *map, void *key, void *next_key){	return -ENOTSUPP;} static struct bpf_map *task_storage_map_alloc(union bpf_attr *attr){	struct bpf_local_storage_map *smap; 	smap = bpf_local_storage_map_alloc(attr);	if (IS_ERR(smap))		return ERR_CAST(smap); 	smap->cache_idx = bpf_local_storage_cache_idx_get(&task_cache);	return &smap->map;} static void task_storage_map_free(struct bpf_map *map){	struct bpf_local_storage_map *smap; 	smap = (struct bpf_local_storage_map *)map;	bpf_local_storage_cache_idx_free(&task_cache, smap->cache_idx);	bpf_local_storage_map_free(smap, &bpf_task_storage_busy);} static int task_storage_map_btf_id;const struct bpf_map_ops task_storage_map_ops = {	.map_meta_equal = bpf_map_meta_equal,	.map_alloc_check = bpf_local_storage_map_alloc_check,	.map_alloc = task_storage_map_alloc,	.map_free = task_storage_map_free,	.map_get_next_key = notsupp_get_next_key,	.map_lookup_elem = bpf_pid_task_storage_lookup_elem,	.map_update_elem = bpf_pid_task_storage_update_elem,	.map_delete_elem = bpf_pid_task_storage_delete_elem,	.map_check_btf = bpf_local_storage_map_check_btf,	.map_btf_name = "bpf_local_storage_map",	.map_btf_id = &task_storage_map_btf_id,	.map_owner_storage_ptr = task_storage_ptr,}; BTF_ID_LIST_SINGLE(bpf_task_storage_btf_ids, struct, task_struct) const struct bpf_func_proto bpf_task_storage_get_proto = {	.func = bpf_task_storage_get,	.gpl_only = false,	.ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,	.arg1_type = ARG_CONST_MAP_PTR,	.arg2_type = ARG_PTR_TO_BTF_ID,	.arg2_btf_id = &bpf_task_storage_btf_ids[0],	.arg3_type = ARG_PTR_TO_MAP_VALUE_OR_NULL,	.arg4_type = ARG_ANYTHING,}; 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 = &bpf_task_storage_btf_ids[0],};