summaryrefslogtreecommitdiff
path: root/kernel/bpf/inode.c
diff options
context:
space:
mode:
authorAndrii Nakryiko <andriin@fb.com>2020-03-02 20:31:57 -0800
committerAlexei Starovoitov <ast@kernel.org>2020-03-02 22:06:27 -0800
commit70ed506c3bbcfa846d4636b23051ca79fa4781f7 (patch)
tree82ef162ee20b4d3b4b501c8768ed1c7c4007d968 /kernel/bpf/inode.c
parent775a2be52da1c55fc810a5d151049f86f0fd5362 (diff)
bpf: Introduce pinnable bpf_link abstraction
Introduce bpf_link abstraction, representing an attachment of BPF program to a BPF hook point (e.g., tracepoint, perf event, etc). bpf_link encapsulates ownership of attached BPF program, reference counting of a link itself, when reference from multiple anonymous inodes, as well as ensures that release callback will be called from a process context, so that users can safely take mutex locks and sleep. Additionally, with a new abstraction it's now possible to generalize pinning of a link object in BPF FS, allowing to explicitly prevent BPF program detachment on process exit by pinning it in a BPF FS and let it open from independent other process to keep working with it. Convert two existing bpf_link-like objects (raw tracepoint and tracing BPF program attachments) into utilizing bpf_link framework, making them pinnable in BPF FS. More FD-based bpf_links will be added in follow up patches. Signed-off-by: Andrii Nakryiko <andriin@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200303043159.323675-2-andriin@fb.com
Diffstat (limited to 'kernel/bpf/inode.c')
-rw-r--r--kernel/bpf/inode.c42
1 files changed, 38 insertions, 4 deletions
diff --git a/kernel/bpf/inode.c b/kernel/bpf/inode.c
index 5e40e7fccc21..95087d9f4ed3 100644
--- a/kernel/bpf/inode.c
+++ b/kernel/bpf/inode.c
@@ -25,6 +25,7 @@ enum bpf_type {
BPF_TYPE_UNSPEC = 0,
BPF_TYPE_PROG,
BPF_TYPE_MAP,
+ BPF_TYPE_LINK,
};
static void *bpf_any_get(void *raw, enum bpf_type type)
@@ -36,6 +37,9 @@ static void *bpf_any_get(void *raw, enum bpf_type type)
case BPF_TYPE_MAP:
bpf_map_inc_with_uref(raw);
break;
+ case BPF_TYPE_LINK:
+ bpf_link_inc(raw);
+ break;
default:
WARN_ON_ONCE(1);
break;
@@ -53,6 +57,9 @@ static void bpf_any_put(void *raw, enum bpf_type type)
case BPF_TYPE_MAP:
bpf_map_put_with_uref(raw);
break;
+ case BPF_TYPE_LINK:
+ bpf_link_put(raw);
+ break;
default:
WARN_ON_ONCE(1);
break;
@@ -63,20 +70,32 @@ static void *bpf_fd_probe_obj(u32 ufd, enum bpf_type *type)
{
void *raw;
- *type = BPF_TYPE_MAP;
raw = bpf_map_get_with_uref(ufd);
- if (IS_ERR(raw)) {
+ if (!IS_ERR(raw)) {
+ *type = BPF_TYPE_MAP;
+ return raw;
+ }
+
+ raw = bpf_prog_get(ufd);
+ if (!IS_ERR(raw)) {
*type = BPF_TYPE_PROG;
- raw = bpf_prog_get(ufd);
+ return raw;
}
- return raw;
+ raw = bpf_link_get_from_fd(ufd);
+ if (!IS_ERR(raw)) {
+ *type = BPF_TYPE_LINK;
+ return raw;
+ }
+
+ return ERR_PTR(-EINVAL);
}
static const struct inode_operations bpf_dir_iops;
static const struct inode_operations bpf_prog_iops = { };
static const struct inode_operations bpf_map_iops = { };
+static const struct inode_operations bpf_link_iops = { };
static struct inode *bpf_get_inode(struct super_block *sb,
const struct inode *dir,
@@ -114,6 +133,8 @@ static int bpf_inode_type(const struct inode *inode, enum bpf_type *type)
*type = BPF_TYPE_PROG;
else if (inode->i_op == &bpf_map_iops)
*type = BPF_TYPE_MAP;
+ else if (inode->i_op == &bpf_link_iops)
+ *type = BPF_TYPE_LINK;
else
return -EACCES;
@@ -335,6 +356,12 @@ static int bpf_mkmap(struct dentry *dentry, umode_t mode, void *arg)
&bpffs_map_fops : &bpffs_obj_fops);
}
+static int bpf_mklink(struct dentry *dentry, umode_t mode, void *arg)
+{
+ return bpf_mkobj_ops(dentry, mode, arg, &bpf_link_iops,
+ &bpffs_obj_fops);
+}
+
static struct dentry *
bpf_lookup(struct inode *dir, struct dentry *dentry, unsigned flags)
{
@@ -411,6 +438,9 @@ static int bpf_obj_do_pin(const char __user *pathname, void *raw,
case BPF_TYPE_MAP:
ret = vfs_mkobj(dentry, mode, bpf_mkmap, raw);
break;
+ case BPF_TYPE_LINK:
+ ret = vfs_mkobj(dentry, mode, bpf_mklink, raw);
+ break;
default:
ret = -EPERM;
}
@@ -487,6 +517,8 @@ int bpf_obj_get_user(const char __user *pathname, int flags)
ret = bpf_prog_new_fd(raw);
else if (type == BPF_TYPE_MAP)
ret = bpf_map_new_fd(raw, f_flags);
+ else if (type == BPF_TYPE_LINK)
+ ret = bpf_link_new_fd(raw);
else
return -ENOENT;
@@ -504,6 +536,8 @@ static struct bpf_prog *__get_prog_inode(struct inode *inode, enum bpf_prog_type
if (inode->i_op == &bpf_map_iops)
return ERR_PTR(-EINVAL);
+ if (inode->i_op == &bpf_link_iops)
+ return ERR_PTR(-EINVAL);
if (inode->i_op != &bpf_prog_iops)
return ERR_PTR(-EACCES);