1 // SPDX-License-Identifier: GPL-2.0
3 * Copyright (c) 2020 Facebook
4 * Copyright 2020 Google LLC.
8 #include <linux/sched.h>
9 #include <linux/rculist.h>
10 #include <linux/list.h>
11 #include <linux/hash.h>
12 #include <linux/types.h>
13 #include <linux/spinlock.h>
14 #include <linux/bpf.h>
15 #include <linux/bpf_local_storage.h>
16 #include <linux/filter.h>
17 #include <uapi/linux/btf.h>
18 #include <linux/bpf_lsm.h>
19 #include <linux/btf_ids.h>
20 #include <linux/fdtable.h>
22 DEFINE_BPF_STORAGE_CACHE(task_cache);
24 static struct bpf_local_storage __rcu **task_storage_ptr(void *owner)
26 struct task_struct *task = owner;
27 struct bpf_storage_blob *bsb;
35 static struct bpf_local_storage_data *
36 task_storage_lookup(struct task_struct *task, struct bpf_map *map,
39 struct bpf_local_storage *task_storage;
40 struct bpf_local_storage_map *smap;
41 struct bpf_storage_blob *bsb;
47 task_storage = rcu_dereference(bsb->storage);
51 smap = (struct bpf_local_storage_map *)map;
52 return bpf_local_storage_lookup(task_storage, smap, cacheit_lockit);
55 void bpf_task_storage_free(struct task_struct *task)
57 struct bpf_local_storage_elem *selem;
58 struct bpf_local_storage *local_storage;
59 bool free_task_storage = false;
60 struct bpf_storage_blob *bsb;
69 local_storage = rcu_dereference(bsb->storage);
75 /* Neither the bpf_prog nor the bpf-map's syscall
76 * could be modifying the local_storage->list now.
77 * Thus, no elem can be added-to or deleted-from the
78 * local_storage->list by the bpf_prog or by the bpf-map's syscall.
80 * It is racing with bpf_local_storage_map_free() alone
81 * when unlinking elem from the local_storage->list and
82 * the map's bucket->list.
84 raw_spin_lock_bh(&local_storage->lock);
85 hlist_for_each_entry_safe(selem, n, &local_storage->list, snode) {
86 /* Always unlink from map before unlinking from
89 bpf_selem_unlink_map(selem);
90 free_task_storage = bpf_selem_unlink_storage_nolock(
91 local_storage, selem, false);
93 raw_spin_unlock_bh(&local_storage->lock);
96 /* free_task_storage should always be true as long as
97 * local_storage->list was non-empty.
99 if (free_task_storage)
100 kfree_rcu(local_storage, rcu);
103 static void *bpf_pid_task_storage_lookup_elem(struct bpf_map *map, void *key)
105 struct bpf_local_storage_data *sdata;
106 struct task_struct *task;
107 unsigned int f_flags;
112 pid = pidfd_get_pid(fd, &f_flags);
114 return ERR_CAST(pid);
116 /* We should be in an RCU read side critical section, it should be safe
119 WARN_ON_ONCE(!rcu_read_lock_held());
120 task = pid_task(pid, PIDTYPE_PID);
126 sdata = task_storage_lookup(task, map, true);
128 return sdata ? sdata->data : NULL;
134 static int bpf_pid_task_storage_update_elem(struct bpf_map *map, void *key,
135 void *value, u64 map_flags)
137 struct bpf_local_storage_data *sdata;
138 struct task_struct *task;
139 unsigned int f_flags;
144 pid = pidfd_get_pid(fd, &f_flags);
148 /* We should be in an RCU read side critical section, it should be safe
151 WARN_ON_ONCE(!rcu_read_lock_held());
152 task = pid_task(pid, PIDTYPE_PID);
153 if (!task || !task_storage_ptr(task)) {
158 sdata = bpf_local_storage_update(
159 task, (struct bpf_local_storage_map *)map, value, map_flags);
161 err = PTR_ERR_OR_ZERO(sdata);
167 static int task_storage_delete(struct task_struct *task, struct bpf_map *map)
169 struct bpf_local_storage_data *sdata;
171 sdata = task_storage_lookup(task, map, false);
175 bpf_selem_unlink(SELEM(sdata));
180 static int bpf_pid_task_storage_delete_elem(struct bpf_map *map, void *key)
182 struct task_struct *task;
183 unsigned int f_flags;
188 pid = pidfd_get_pid(fd, &f_flags);
192 /* We should be in an RCU read side critical section, it should be safe
195 WARN_ON_ONCE(!rcu_read_lock_held());
196 task = pid_task(pid, PIDTYPE_PID);
202 err = task_storage_delete(task, map);
208 BPF_CALL_4(bpf_task_storage_get, struct bpf_map *, map, struct task_struct *,
209 task, void *, value, u64, flags)
211 struct bpf_local_storage_data *sdata;
213 if (flags & ~(BPF_LOCAL_STORAGE_GET_F_CREATE))
214 return (unsigned long)NULL;
216 /* explicitly check that the task_storage_ptr is not
217 * NULL as task_storage_lookup returns NULL in this case and
218 * bpf_local_storage_update expects the owner to have a
219 * valid storage pointer.
221 if (!task || !task_storage_ptr(task))
222 return (unsigned long)NULL;
224 sdata = task_storage_lookup(task, map, true);
226 return (unsigned long)sdata->data;
228 /* This helper must only be called from places where the lifetime of the task
229 * is guaranteed. Either by being refcounted or by being protected
230 * by an RCU read-side critical section.
232 if (flags & BPF_LOCAL_STORAGE_GET_F_CREATE) {
233 sdata = bpf_local_storage_update(
234 task, (struct bpf_local_storage_map *)map, value,
236 return IS_ERR(sdata) ? (unsigned long)NULL :
237 (unsigned long)sdata->data;
240 return (unsigned long)NULL;
243 BPF_CALL_2(bpf_task_storage_delete, struct bpf_map *, map, struct task_struct *,
249 /* This helper must only be called from places where the lifetime of the task
250 * is guaranteed. Either by being refcounted or by being protected
251 * by an RCU read-side critical section.
253 return task_storage_delete(task, map);
256 static int notsupp_get_next_key(struct bpf_map *map, void *key, void *next_key)
261 static struct bpf_map *task_storage_map_alloc(union bpf_attr *attr)
263 struct bpf_local_storage_map *smap;
265 smap = bpf_local_storage_map_alloc(attr);
267 return ERR_CAST(smap);
269 smap->cache_idx = bpf_local_storage_cache_idx_get(&task_cache);
273 static void task_storage_map_free(struct bpf_map *map)
275 struct bpf_local_storage_map *smap;
277 smap = (struct bpf_local_storage_map *)map;
278 bpf_local_storage_cache_idx_free(&task_cache, smap->cache_idx);
279 bpf_local_storage_map_free(smap);
282 static int task_storage_map_btf_id;
283 const struct bpf_map_ops task_storage_map_ops = {
284 .map_meta_equal = bpf_map_meta_equal,
285 .map_alloc_check = bpf_local_storage_map_alloc_check,
286 .map_alloc = task_storage_map_alloc,
287 .map_free = task_storage_map_free,
288 .map_get_next_key = notsupp_get_next_key,
289 .map_lookup_elem = bpf_pid_task_storage_lookup_elem,
290 .map_update_elem = bpf_pid_task_storage_update_elem,
291 .map_delete_elem = bpf_pid_task_storage_delete_elem,
292 .map_check_btf = bpf_local_storage_map_check_btf,
293 .map_btf_name = "bpf_local_storage_map",
294 .map_btf_id = &task_storage_map_btf_id,
295 .map_owner_storage_ptr = task_storage_ptr,
298 BTF_ID_LIST_SINGLE(bpf_task_storage_btf_ids, struct, task_struct)
300 const struct bpf_func_proto bpf_task_storage_get_proto = {
301 .func = bpf_task_storage_get,
303 .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
304 .arg1_type = ARG_CONST_MAP_PTR,
305 .arg2_type = ARG_PTR_TO_BTF_ID,
306 .arg2_btf_id = &bpf_task_storage_btf_ids[0],
307 .arg3_type = ARG_PTR_TO_MAP_VALUE_OR_NULL,
308 .arg4_type = ARG_ANYTHING,
311 const struct bpf_func_proto bpf_task_storage_delete_proto = {
312 .func = bpf_task_storage_delete,
314 .ret_type = RET_INTEGER,
315 .arg1_type = ARG_CONST_MAP_PTR,
316 .arg2_type = ARG_PTR_TO_BTF_ID,
317 .arg2_btf_id = &bpf_task_storage_btf_ids[0],