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-rw-r--r--include/linux/bpf.h2
-rw-r--r--include/uapi/linux/bpf.h1
-rw-r--r--kernel/bpf/arraymap.c24
-rw-r--r--kernel/bpf/hashtab.c42
-rw-r--r--kernel/bpf/helpers.c16
-rw-r--r--kernel/bpf/local_storage.c14
-rw-r--r--kernel/bpf/syscall.c25
7 files changed, 110 insertions, 14 deletions
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index 2ae615b48bb8..bd169a7bcc93 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -119,6 +119,8 @@ static inline void copy_map_value(struct bpf_map *map, void *dst, void *src)
memcpy(dst, src, map->value_size);
}
}
+void copy_map_value_locked(struct bpf_map *map, void *dst, void *src,
+ bool lock_src);
struct bpf_offload_dev;
struct bpf_offloaded_map;
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 86f7c438d40f..1777fa0c61e4 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -267,6 +267,7 @@ enum bpf_attach_type {
#define BPF_ANY 0 /* create new element or update existing */
#define BPF_NOEXIST 1 /* create new element if it didn't exist */
#define BPF_EXIST 2 /* update existing element */
+#define BPF_F_LOCK 4 /* spin_lock-ed map_lookup/map_update */
/* flags for BPF_MAP_CREATE command */
#define BPF_F_NO_PREALLOC (1U << 0)
diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index d6d979910a2a..c72e0d8e1e65 100644
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -253,8 +253,9 @@ static int array_map_update_elem(struct bpf_map *map, void *key, void *value,
{
struct bpf_array *array = container_of(map, struct bpf_array, map);
u32 index = *(u32 *)key;
+ char *val;
- if (unlikely(map_flags > BPF_EXIST))
+ if (unlikely((map_flags & ~BPF_F_LOCK) > BPF_EXIST))
/* unknown flags */
return -EINVAL;
@@ -262,18 +263,25 @@ static int array_map_update_elem(struct bpf_map *map, void *key, void *value,
/* all elements were pre-allocated, cannot insert a new one */
return -E2BIG;
- if (unlikely(map_flags == BPF_NOEXIST))
+ if (unlikely(map_flags & BPF_NOEXIST))
/* all elements already exist */
return -EEXIST;
- if (array->map.map_type == BPF_MAP_TYPE_PERCPU_ARRAY)
+ if (unlikely((map_flags & BPF_F_LOCK) &&
+ !map_value_has_spin_lock(map)))
+ return -EINVAL;
+
+ if (array->map.map_type == BPF_MAP_TYPE_PERCPU_ARRAY) {
memcpy(this_cpu_ptr(array->pptrs[index & array->index_mask]),
value, map->value_size);
- else
- copy_map_value(map,
- array->value +
- array->elem_size * (index & array->index_mask),
- value);
+ } else {
+ val = array->value +
+ array->elem_size * (index & array->index_mask);
+ if (map_flags & BPF_F_LOCK)
+ copy_map_value_locked(map, val, value, false);
+ else
+ copy_map_value(map, val, value);
+ }
return 0;
}
diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
index 6d3b22c5ad68..937776531998 100644
--- a/kernel/bpf/hashtab.c
+++ b/kernel/bpf/hashtab.c
@@ -804,11 +804,11 @@ dec_count:
static int check_flags(struct bpf_htab *htab, struct htab_elem *l_old,
u64 map_flags)
{
- if (l_old && map_flags == BPF_NOEXIST)
+ if (l_old && (map_flags & ~BPF_F_LOCK) == BPF_NOEXIST)
/* elem already exists */
return -EEXIST;
- if (!l_old && map_flags == BPF_EXIST)
+ if (!l_old && (map_flags & ~BPF_F_LOCK) == BPF_EXIST)
/* elem doesn't exist, cannot update it */
return -ENOENT;
@@ -827,7 +827,7 @@ static int htab_map_update_elem(struct bpf_map *map, void *key, void *value,
u32 key_size, hash;
int ret;
- if (unlikely(map_flags > BPF_EXIST))
+ if (unlikely((map_flags & ~BPF_F_LOCK) > BPF_EXIST))
/* unknown flags */
return -EINVAL;
@@ -840,6 +840,28 @@ static int htab_map_update_elem(struct bpf_map *map, void *key, void *value,
b = __select_bucket(htab, hash);
head = &b->head;
+ if (unlikely(map_flags & BPF_F_LOCK)) {
+ if (unlikely(!map_value_has_spin_lock(map)))
+ return -EINVAL;
+ /* find an element without taking the bucket lock */
+ l_old = lookup_nulls_elem_raw(head, hash, key, key_size,
+ htab->n_buckets);
+ ret = check_flags(htab, l_old, map_flags);
+ if (ret)
+ return ret;
+ if (l_old) {
+ /* grab the element lock and update value in place */
+ copy_map_value_locked(map,
+ l_old->key + round_up(key_size, 8),
+ value, false);
+ return 0;
+ }
+ /* fall through, grab the bucket lock and lookup again.
+ * 99.9% chance that the element won't be found,
+ * but second lookup under lock has to be done.
+ */
+ }
+
/* bpf_map_update_elem() can be called in_irq() */
raw_spin_lock_irqsave(&b->lock, flags);
@@ -849,6 +871,20 @@ static int htab_map_update_elem(struct bpf_map *map, void *key, void *value,
if (ret)
goto err;
+ if (unlikely(l_old && (map_flags & BPF_F_LOCK))) {
+ /* first lookup without the bucket lock didn't find the element,
+ * but second lookup with the bucket lock found it.
+ * This case is highly unlikely, but has to be dealt with:
+ * grab the element lock in addition to the bucket lock
+ * and update element in place
+ */
+ copy_map_value_locked(map,
+ l_old->key + round_up(key_size, 8),
+ value, false);
+ ret = 0;
+ goto err;
+ }
+
l_new = alloc_htab_elem(htab, key, value, key_size, hash, false, false,
l_old);
if (IS_ERR(l_new)) {
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index fbe544761628..a411fc17d265 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -301,6 +301,22 @@ const struct bpf_func_proto bpf_spin_unlock_proto = {
.arg1_type = ARG_PTR_TO_SPIN_LOCK,
};
+void copy_map_value_locked(struct bpf_map *map, void *dst, void *src,
+ bool lock_src)
+{
+ struct bpf_spin_lock *lock;
+
+ if (lock_src)
+ lock = src + map->spin_lock_off;
+ else
+ lock = dst + map->spin_lock_off;
+ preempt_disable();
+ ____bpf_spin_lock(lock);
+ copy_map_value(map, dst, src);
+ ____bpf_spin_unlock(lock);
+ preempt_enable();
+}
+
#ifdef CONFIG_CGROUPS
BPF_CALL_0(bpf_get_current_cgroup_id)
{
diff --git a/kernel/bpf/local_storage.c b/kernel/bpf/local_storage.c
index 0295427f06e2..6b572e2de7fb 100644
--- a/kernel/bpf/local_storage.c
+++ b/kernel/bpf/local_storage.c
@@ -131,7 +131,14 @@ static int cgroup_storage_update_elem(struct bpf_map *map, void *_key,
struct bpf_cgroup_storage *storage;
struct bpf_storage_buffer *new;
- if (flags != BPF_ANY && flags != BPF_EXIST)
+ if (unlikely(flags & ~(BPF_F_LOCK | BPF_EXIST | BPF_NOEXIST)))
+ return -EINVAL;
+
+ if (unlikely(flags & BPF_NOEXIST))
+ return -EINVAL;
+
+ if (unlikely((flags & BPF_F_LOCK) &&
+ !map_value_has_spin_lock(map)))
return -EINVAL;
storage = cgroup_storage_lookup((struct bpf_cgroup_storage_map *)map,
@@ -139,6 +146,11 @@ static int cgroup_storage_update_elem(struct bpf_map *map, void *_key,
if (!storage)
return -ENOENT;
+ if (flags & BPF_F_LOCK) {
+ copy_map_value_locked(map, storage->buf->data, value, false);
+ return 0;
+ }
+
new = kmalloc_node(sizeof(struct bpf_storage_buffer) +
map->value_size,
__GFP_ZERO | GFP_ATOMIC | __GFP_NOWARN,
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index b29e6dc44650..0834958f1dc4 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -682,7 +682,7 @@ static void *__bpf_copy_key(void __user *ukey, u64 key_size)
}
/* last field in 'union bpf_attr' used by this command */
-#define BPF_MAP_LOOKUP_ELEM_LAST_FIELD value
+#define BPF_MAP_LOOKUP_ELEM_LAST_FIELD flags
static int map_lookup_elem(union bpf_attr *attr)
{
@@ -698,6 +698,9 @@ static int map_lookup_elem(union bpf_attr *attr)
if (CHECK_ATTR(BPF_MAP_LOOKUP_ELEM))
return -EINVAL;
+ if (attr->flags & ~BPF_F_LOCK)
+ return -EINVAL;
+
f = fdget(ufd);
map = __bpf_map_get(f);
if (IS_ERR(map))
@@ -708,6 +711,12 @@ static int map_lookup_elem(union bpf_attr *attr)
goto err_put;
}
+ if ((attr->flags & BPF_F_LOCK) &&
+ !map_value_has_spin_lock(map)) {
+ err = -EINVAL;
+ goto err_put;
+ }
+
key = __bpf_copy_key(ukey, map->key_size);
if (IS_ERR(key)) {
err = PTR_ERR(key);
@@ -758,7 +767,13 @@ static int map_lookup_elem(union bpf_attr *attr)
err = -ENOENT;
} else {
err = 0;
- copy_map_value(map, value, ptr);
+ if (attr->flags & BPF_F_LOCK)
+ /* lock 'ptr' and copy everything but lock */
+ copy_map_value_locked(map, value, ptr, true);
+ else
+ copy_map_value(map, value, ptr);
+ /* mask lock, since value wasn't zero inited */
+ check_and_init_map_lock(map, value);
}
rcu_read_unlock();
}
@@ -818,6 +833,12 @@ static int map_update_elem(union bpf_attr *attr)
goto err_put;
}
+ if ((attr->flags & BPF_F_LOCK) &&
+ !map_value_has_spin_lock(map)) {
+ err = -EINVAL;
+ goto err_put;
+ }
+
key = __bpf_copy_key(ukey, map->key_size);
if (IS_ERR(key)) {
err = PTR_ERR(key);
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.