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authorAlexei Starovoitov <ast@plumgrid.com>2014-09-26 00:16:59 -0700
committerDavid S. Miller <davem@davemloft.net>2014-09-26 15:05:14 -0400
commitdb20fd2b01087bdfbe30bce314a198eefedcc42e (patch)
treec43a4e3edb46deae542c8e79d74d24703ffbdcca /kernel/bpf/syscall.c
parent749730ce42a2121e1c88350d69478bff3994b10a (diff)
downloadlinux-sh-db20fd2b01087bdfbe30bce314a198eefedcc42e.tar.gz
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>
Diffstat (limited to 'kernel/bpf/syscall.c')
-rw-r--r--kernel/bpf/syscall.c235
1 files changed, 235 insertions, 0 deletions
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 428a0e23adc0..f94349ecaf61 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -13,6 +13,7 @@
#include <linux/syscalls.h>
#include <linux/slab.h>
#include <linux/anon_inodes.h>
+#include <linux/file.h>
static LIST_HEAD(bpf_map_types);
@@ -111,6 +112,228 @@ free_map:
return err;
}
+/* if error is returned, fd is released.
+ * On success caller should complete fd access with matching fdput()
+ */
+struct bpf_map *bpf_map_get(struct fd f)
+{
+ struct bpf_map *map;
+
+ if (!f.file)
+ return ERR_PTR(-EBADF);
+
+ if (f.file->f_op != &bpf_map_fops) {
+ fdput(f);
+ return ERR_PTR(-EINVAL);
+ }
+
+ map = f.file->private_data;
+
+ return map;
+}
+
+/* helper to convert user pointers passed inside __aligned_u64 fields */
+static void __user *u64_to_ptr(__u64 val)
+{
+ return (void __user *) (unsigned long) val;
+}
+
+/* last field in 'union bpf_attr' used by this command */
+#define BPF_MAP_LOOKUP_ELEM_LAST_FIELD value
+
+static int map_lookup_elem(union bpf_attr *attr)
+{
+ void __user *ukey = u64_to_ptr(attr->key);
+ void __user *uvalue = u64_to_ptr(attr->value);
+ int ufd = attr->map_fd;
+ struct fd f = fdget(ufd);
+ struct bpf_map *map;
+ void *key, *value;
+ int err;
+
+ if (CHECK_ATTR(BPF_MAP_LOOKUP_ELEM))
+ return -EINVAL;
+
+ map = bpf_map_get(f);
+ if (IS_ERR(map))
+ return PTR_ERR(map);
+
+ err = -ENOMEM;
+ key = kmalloc(map->key_size, GFP_USER);
+ if (!key)
+ goto err_put;
+
+ err = -EFAULT;
+ if (copy_from_user(key, ukey, map->key_size) != 0)
+ goto free_key;
+
+ err = -ESRCH;
+ rcu_read_lock();
+ value = map->ops->map_lookup_elem(map, key);
+ if (!value)
+ goto err_unlock;
+
+ err = -EFAULT;
+ if (copy_to_user(uvalue, value, map->value_size) != 0)
+ goto err_unlock;
+
+ err = 0;
+
+err_unlock:
+ rcu_read_unlock();
+free_key:
+ kfree(key);
+err_put:
+ fdput(f);
+ return err;
+}
+
+#define BPF_MAP_UPDATE_ELEM_LAST_FIELD value
+
+static int map_update_elem(union bpf_attr *attr)
+{
+ void __user *ukey = u64_to_ptr(attr->key);
+ void __user *uvalue = u64_to_ptr(attr->value);
+ int ufd = attr->map_fd;
+ struct fd f = fdget(ufd);
+ struct bpf_map *map;
+ void *key, *value;
+ int err;
+
+ if (CHECK_ATTR(BPF_MAP_UPDATE_ELEM))
+ return -EINVAL;
+
+ map = bpf_map_get(f);
+ if (IS_ERR(map))
+ return PTR_ERR(map);
+
+ err = -ENOMEM;
+ key = kmalloc(map->key_size, GFP_USER);
+ if (!key)
+ goto err_put;
+
+ err = -EFAULT;
+ if (copy_from_user(key, ukey, map->key_size) != 0)
+ goto free_key;
+
+ err = -ENOMEM;
+ value = kmalloc(map->value_size, GFP_USER);
+ if (!value)
+ goto free_key;
+
+ err = -EFAULT;
+ if (copy_from_user(value, uvalue, map->value_size) != 0)
+ goto free_value;
+
+ /* eBPF program that use maps are running under rcu_read_lock(),
+ * therefore all map accessors rely on this fact, so do the same here
+ */
+ rcu_read_lock();
+ err = map->ops->map_update_elem(map, key, value);
+ rcu_read_unlock();
+
+free_value:
+ kfree(value);
+free_key:
+ kfree(key);
+err_put:
+ fdput(f);
+ return err;
+}
+
+#define BPF_MAP_DELETE_ELEM_LAST_FIELD key
+
+static int map_delete_elem(union bpf_attr *attr)
+{
+ void __user *ukey = u64_to_ptr(attr->key);
+ int ufd = attr->map_fd;
+ struct fd f = fdget(ufd);
+ struct bpf_map *map;
+ void *key;
+ int err;
+
+ if (CHECK_ATTR(BPF_MAP_DELETE_ELEM))
+ return -EINVAL;
+
+ map = bpf_map_get(f);
+ if (IS_ERR(map))
+ return PTR_ERR(map);
+
+ err = -ENOMEM;
+ key = kmalloc(map->key_size, GFP_USER);
+ if (!key)
+ goto err_put;
+
+ err = -EFAULT;
+ if (copy_from_user(key, ukey, map->key_size) != 0)
+ goto free_key;
+
+ rcu_read_lock();
+ err = map->ops->map_delete_elem(map, key);
+ rcu_read_unlock();
+
+free_key:
+ kfree(key);
+err_put:
+ fdput(f);
+ return err;
+}
+
+/* last field in 'union bpf_attr' used by this command */
+#define BPF_MAP_GET_NEXT_KEY_LAST_FIELD next_key
+
+static int map_get_next_key(union bpf_attr *attr)
+{
+ void __user *ukey = u64_to_ptr(attr->key);
+ void __user *unext_key = u64_to_ptr(attr->next_key);
+ int ufd = attr->map_fd;
+ struct fd f = fdget(ufd);
+ struct bpf_map *map;
+ void *key, *next_key;
+ int err;
+
+ if (CHECK_ATTR(BPF_MAP_GET_NEXT_KEY))
+ return -EINVAL;
+
+ map = bpf_map_get(f);
+ if (IS_ERR(map))
+ return PTR_ERR(map);
+
+ err = -ENOMEM;
+ key = kmalloc(map->key_size, GFP_USER);
+ if (!key)
+ goto err_put;
+
+ err = -EFAULT;
+ if (copy_from_user(key, ukey, map->key_size) != 0)
+ goto free_key;
+
+ err = -ENOMEM;
+ next_key = kmalloc(map->key_size, GFP_USER);
+ if (!next_key)
+ goto free_key;
+
+ rcu_read_lock();
+ err = map->ops->map_get_next_key(map, key, next_key);
+ rcu_read_unlock();
+ if (err)
+ goto free_next_key;
+
+ err = -EFAULT;
+ if (copy_to_user(unext_key, next_key, map->key_size) != 0)
+ goto free_next_key;
+
+ err = 0;
+
+free_next_key:
+ kfree(next_key);
+free_key:
+ kfree(key);
+err_put:
+ fdput(f);
+ return err;
+}
+
SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, size)
{
union bpf_attr attr = {};
@@ -160,6 +383,18 @@ SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, siz
case BPF_MAP_CREATE:
err = map_create(&attr);
break;
+ case BPF_MAP_LOOKUP_ELEM:
+ err = map_lookup_elem(&attr);
+ break;
+ case BPF_MAP_UPDATE_ELEM:
+ err = map_update_elem(&attr);
+ break;
+ case BPF_MAP_DELETE_ELEM:
+ err = map_delete_elem(&attr);
+ break;
+ case BPF_MAP_GET_NEXT_KEY:
+ err = map_get_next_key(&attr);
+ break;
default:
err = -EINVAL;
break;