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authorJakub Sitnicki <jakub@cloudflare.com>2020-05-31 10:28:38 +0200
committerAlexei Starovoitov <ast@kernel.org>2020-06-01 15:21:03 -0700
commit7f045a49fee04b5662cbdeaf0838f9322ae8c63a (patch)
treedece77e22630b3ebb07fefe626c652573509690b /include/net
parentb27f7bb590ba835b32ef122389db158e44cfda1e (diff)
downloadlinux-7f045a49fee04b5662cbdeaf0838f9322ae8c63a.tar.bz2
bpf: Add link-based BPF program attachment to network namespace
Extend bpf() syscall subcommands that operate on bpf_link, that is LINK_CREATE, LINK_UPDATE, OBJ_GET_INFO, to accept attach types tied to network namespaces (only flow dissector at the moment). Link-based and prog-based attachment can be used interchangeably, but only one can exist at a time. Attempts to attach a link when a prog is already attached directly, and the other way around, will be met with -EEXIST. Attempts to detach a program when link exists result in -EINVAL. Attachment of multiple links of same attach type to one netns is not supported with the intention to lift the restriction when a use-case presents itself. Because of that link create returns -E2BIG when trying to create another netns link, when one already exists. Link-based attachments to netns don't keep a netns alive by holding a ref to it. Instead links get auto-detached from netns when the latter is being destroyed, using a pernet pre_exit callback. When auto-detached, link lives in defunct state as long there are open FDs for it. -ENOLINK is returned if a user tries to update a defunct link. Because bpf_link to netns doesn't hold a ref to struct net, special care is taken when releasing, updating, or filling link info. The netns might be getting torn down when any of these link operations are in progress. That is why auto-detach and update/release/fill_info are synchronized by the same mutex. Also, link ops have to always check if auto-detach has not happened yet and if netns is still alive (refcnt > 0). Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20200531082846.2117903-5-jakub@cloudflare.com
Diffstat (limited to 'include/net')
-rw-r--r--include/net/netns/bpf.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/include/net/netns/bpf.h b/include/net/netns/bpf.h
index a858d1c5b166..a8dce2a380c8 100644
--- a/include/net/netns/bpf.h
+++ b/include/net/netns/bpf.h
@@ -12,6 +12,7 @@ struct bpf_prog;
struct netns_bpf {
struct bpf_prog __rcu *progs[MAX_NETNS_BPF_ATTACH_TYPE];
+ struct bpf_link *links[MAX_NETNS_BPF_ATTACH_TYPE];
};
#endif /* __NETNS_BPF_H__ */