forked from Minki/linux
bpf: add lookup/update/delete/iterate methods to BPF maps
'maps' is a generic storage of different types for sharing data between kernel and userspace. The maps are accessed from user space via BPF syscall, which has commands: - create a map with given type and attributes fd = bpf(BPF_MAP_CREATE, union bpf_attr *attr, u32 size) returns fd or negative error - lookup key in a given map referenced by fd err = bpf(BPF_MAP_LOOKUP_ELEM, union bpf_attr *attr, u32 size) using attr->map_fd, attr->key, attr->value returns zero and stores found elem into value or negative error - create or update key/value pair in a given map err = bpf(BPF_MAP_UPDATE_ELEM, union bpf_attr *attr, u32 size) using attr->map_fd, attr->key, attr->value returns zero or negative error - find and delete element by key in a given map err = bpf(BPF_MAP_DELETE_ELEM, union bpf_attr *attr, u32 size) using attr->map_fd, attr->key - iterate map elements (based on input key return next_key) err = bpf(BPF_MAP_GET_NEXT_KEY, union bpf_attr *attr, u32 size) using attr->map_fd, attr->key, attr->next_key - close(fd) deletes the map Signed-off-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alexei Starovoitov
David S. Miller
parent
749730ce42
commit
db20fd2b01
@ -9,6 +9,7 @@
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#include <uapi/linux/bpf.h>
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#include <linux/workqueue.h>
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#include <linux/file.h>
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struct bpf_map;
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@ -17,6 +18,12 @@ struct bpf_map_ops {
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/* funcs callable from userspace (via syscall) */
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struct bpf_map *(*map_alloc)(union bpf_attr *attr);
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void (*map_free)(struct bpf_map *);
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int (*map_get_next_key)(struct bpf_map *map, void *key, void *next_key);
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/* funcs callable from userspace and from eBPF programs */
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void *(*map_lookup_elem)(struct bpf_map *map, void *key);
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int (*map_update_elem)(struct bpf_map *map, void *key, void *value);
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int (*map_delete_elem)(struct bpf_map *map, void *key);
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};
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struct bpf_map {
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@ -37,5 +44,6 @@ struct bpf_map_type_list {
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void bpf_register_map_type(struct bpf_map_type_list *tl);
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void bpf_map_put(struct bpf_map *map);
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struct bpf_map *bpf_map_get(struct fd f);
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#endif /* _LINUX_BPF_H */
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@ -70,6 +70,35 @@ enum bpf_cmd {
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* map is deleted when fd is closed
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*/
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BPF_MAP_CREATE,
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/* lookup key in a given map
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* err = bpf(BPF_MAP_LOOKUP_ELEM, union bpf_attr *attr, u32 size)
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* Using attr->map_fd, attr->key, attr->value
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* returns zero and stores found elem into value
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* or negative error
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*/
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BPF_MAP_LOOKUP_ELEM,
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/* create or update key/value pair in a given map
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* err = bpf(BPF_MAP_UPDATE_ELEM, union bpf_attr *attr, u32 size)
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* Using attr->map_fd, attr->key, attr->value
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* returns zero or negative error
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*/
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BPF_MAP_UPDATE_ELEM,
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/* find and delete elem by key in a given map
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* err = bpf(BPF_MAP_DELETE_ELEM, union bpf_attr *attr, u32 size)
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* Using attr->map_fd, attr->key
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* returns zero or negative error
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*/
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BPF_MAP_DELETE_ELEM,
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/* lookup key in a given map and return next key
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* err = bpf(BPF_MAP_GET_NEXT_KEY, union bpf_attr *attr, u32 size)
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* Using attr->map_fd, attr->key, attr->next_key
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* returns zero and stores next key or negative error
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*/
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BPF_MAP_GET_NEXT_KEY,
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};
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enum bpf_map_type {
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@ -83,6 +112,15 @@ union bpf_attr {
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__u32 value_size; /* size of value in bytes */
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__u32 max_entries; /* max number of entries in a map */
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};
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struct { /* anonymous struct used by BPF_MAP_*_ELEM commands */
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__u32 map_fd;
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__aligned_u64 key;
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union {
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__aligned_u64 value;
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__aligned_u64 next_key;
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};
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};
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} __attribute__((aligned(8)));
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#endif /* _UAPI__LINUX_BPF_H__ */
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@ -13,6 +13,7 @@
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#include <linux/syscalls.h>
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#include <linux/slab.h>
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#include <linux/anon_inodes.h>
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#include <linux/file.h>
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static LIST_HEAD(bpf_map_types);
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@ -111,6 +112,228 @@ free_map:
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return err;
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}
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/* if error is returned, fd is released.
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* On success caller should complete fd access with matching fdput()
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*/
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struct bpf_map *bpf_map_get(struct fd f)
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{
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struct bpf_map *map;
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if (!f.file)
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return ERR_PTR(-EBADF);
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if (f.file->f_op != &bpf_map_fops) {
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fdput(f);
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return ERR_PTR(-EINVAL);
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}
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map = f.file->private_data;
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return map;
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}
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/* helper to convert user pointers passed inside __aligned_u64 fields */
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static void __user *u64_to_ptr(__u64 val)
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{
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return (void __user *) (unsigned long) val;
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}
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/* last field in 'union bpf_attr' used by this command */
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#define BPF_MAP_LOOKUP_ELEM_LAST_FIELD value
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static int map_lookup_elem(union bpf_attr *attr)
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{
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void __user *ukey = u64_to_ptr(attr->key);
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void __user *uvalue = u64_to_ptr(attr->value);
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int ufd = attr->map_fd;
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struct fd f = fdget(ufd);
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struct bpf_map *map;
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void *key, *value;
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int err;
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if (CHECK_ATTR(BPF_MAP_LOOKUP_ELEM))
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return -EINVAL;
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map = bpf_map_get(f);
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if (IS_ERR(map))
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return PTR_ERR(map);
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err = -ENOMEM;
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key = kmalloc(map->key_size, GFP_USER);
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if (!key)
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goto err_put;
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err = -EFAULT;
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if (copy_from_user(key, ukey, map->key_size) != 0)
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goto free_key;
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err = -ESRCH;
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rcu_read_lock();
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value = map->ops->map_lookup_elem(map, key);
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if (!value)
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goto err_unlock;
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err = -EFAULT;
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if (copy_to_user(uvalue, value, map->value_size) != 0)
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goto err_unlock;
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err = 0;
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err_unlock:
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rcu_read_unlock();
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free_key:
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kfree(key);
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err_put:
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fdput(f);
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return err;
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}
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#define BPF_MAP_UPDATE_ELEM_LAST_FIELD value
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static int map_update_elem(union bpf_attr *attr)
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{
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void __user *ukey = u64_to_ptr(attr->key);
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void __user *uvalue = u64_to_ptr(attr->value);
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int ufd = attr->map_fd;
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struct fd f = fdget(ufd);
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struct bpf_map *map;
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void *key, *value;
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int err;
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if (CHECK_ATTR(BPF_MAP_UPDATE_ELEM))
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return -EINVAL;
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map = bpf_map_get(f);
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if (IS_ERR(map))
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return PTR_ERR(map);
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err = -ENOMEM;
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key = kmalloc(map->key_size, GFP_USER);
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if (!key)
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goto err_put;
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err = -EFAULT;
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if (copy_from_user(key, ukey, map->key_size) != 0)
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goto free_key;
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err = -ENOMEM;
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value = kmalloc(map->value_size, GFP_USER);
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if (!value)
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goto free_key;
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err = -EFAULT;
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if (copy_from_user(value, uvalue, map->value_size) != 0)
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goto free_value;
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/* eBPF program that use maps are running under rcu_read_lock(),
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* therefore all map accessors rely on this fact, so do the same here
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*/
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rcu_read_lock();
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err = map->ops->map_update_elem(map, key, value);
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rcu_read_unlock();
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free_value:
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kfree(value);
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free_key:
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kfree(key);
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err_put:
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fdput(f);
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return err;
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}
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#define BPF_MAP_DELETE_ELEM_LAST_FIELD key
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static int map_delete_elem(union bpf_attr *attr)
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{
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void __user *ukey = u64_to_ptr(attr->key);
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int ufd = attr->map_fd;
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struct fd f = fdget(ufd);
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struct bpf_map *map;
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void *key;
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int err;
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if (CHECK_ATTR(BPF_MAP_DELETE_ELEM))
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return -EINVAL;
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map = bpf_map_get(f);
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if (IS_ERR(map))
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return PTR_ERR(map);
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err = -ENOMEM;
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key = kmalloc(map->key_size, GFP_USER);
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if (!key)
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goto err_put;
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err = -EFAULT;
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if (copy_from_user(key, ukey, map->key_size) != 0)
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goto free_key;
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rcu_read_lock();
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err = map->ops->map_delete_elem(map, key);
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rcu_read_unlock();
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free_key:
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kfree(key);
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err_put:
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fdput(f);
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return err;
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}
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/* last field in 'union bpf_attr' used by this command */
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#define BPF_MAP_GET_NEXT_KEY_LAST_FIELD next_key
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static int map_get_next_key(union bpf_attr *attr)
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{
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void __user *ukey = u64_to_ptr(attr->key);
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void __user *unext_key = u64_to_ptr(attr->next_key);
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int ufd = attr->map_fd;
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struct fd f = fdget(ufd);
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struct bpf_map *map;
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void *key, *next_key;
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int err;
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if (CHECK_ATTR(BPF_MAP_GET_NEXT_KEY))
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return -EINVAL;
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map = bpf_map_get(f);
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if (IS_ERR(map))
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return PTR_ERR(map);
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err = -ENOMEM;
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key = kmalloc(map->key_size, GFP_USER);
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if (!key)
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goto err_put;
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err = -EFAULT;
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if (copy_from_user(key, ukey, map->key_size) != 0)
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goto free_key;
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err = -ENOMEM;
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next_key = kmalloc(map->key_size, GFP_USER);
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if (!next_key)
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goto free_key;
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rcu_read_lock();
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err = map->ops->map_get_next_key(map, key, next_key);
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rcu_read_unlock();
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if (err)
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goto free_next_key;
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err = -EFAULT;
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if (copy_to_user(unext_key, next_key, map->key_size) != 0)
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goto free_next_key;
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err = 0;
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free_next_key:
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kfree(next_key);
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free_key:
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kfree(key);
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err_put:
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fdput(f);
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return err;
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}
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SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, size)
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{
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union bpf_attr attr = {};
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@ -160,6 +383,18 @@ SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, siz
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case BPF_MAP_CREATE:
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err = map_create(&attr);
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break;
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case BPF_MAP_LOOKUP_ELEM:
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err = map_lookup_elem(&attr);
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break;
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case BPF_MAP_UPDATE_ELEM:
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err = map_update_elem(&attr);
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break;
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case BPF_MAP_DELETE_ELEM:
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err = map_delete_elem(&attr);
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break;
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case BPF_MAP_GET_NEXT_KEY:
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err = map_get_next_key(&attr);
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break;
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default:
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err = -EINVAL;
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break;
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