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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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7f045a49fe
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
65 lines
1.4 KiB
C
65 lines
1.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _BPF_NETNS_H
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#define _BPF_NETNS_H
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#include <linux/mutex.h>
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#include <uapi/linux/bpf.h>
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enum netns_bpf_attach_type {
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NETNS_BPF_INVALID = -1,
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NETNS_BPF_FLOW_DISSECTOR = 0,
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MAX_NETNS_BPF_ATTACH_TYPE
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};
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static inline enum netns_bpf_attach_type
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to_netns_bpf_attach_type(enum bpf_attach_type attach_type)
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{
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switch (attach_type) {
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case BPF_FLOW_DISSECTOR:
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return NETNS_BPF_FLOW_DISSECTOR;
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default:
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return NETNS_BPF_INVALID;
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}
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}
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/* Protects updates to netns_bpf */
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extern struct mutex netns_bpf_mutex;
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union bpf_attr;
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struct bpf_prog;
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#ifdef CONFIG_NET
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int netns_bpf_prog_query(const union bpf_attr *attr,
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union bpf_attr __user *uattr);
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int netns_bpf_prog_attach(const union bpf_attr *attr,
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struct bpf_prog *prog);
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int netns_bpf_prog_detach(const union bpf_attr *attr);
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int netns_bpf_link_create(const union bpf_attr *attr,
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struct bpf_prog *prog);
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#else
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static inline int netns_bpf_prog_query(const union bpf_attr *attr,
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union bpf_attr __user *uattr)
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{
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return -EOPNOTSUPP;
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}
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static inline int netns_bpf_prog_attach(const union bpf_attr *attr,
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struct bpf_prog *prog)
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{
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return -EOPNOTSUPP;
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}
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static inline int netns_bpf_prog_detach(const union bpf_attr *attr)
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{
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return -EOPNOTSUPP;
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}
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static inline int netns_bpf_link_create(const union bpf_attr *attr,
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struct bpf_prog *prog)
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{
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return -EOPNOTSUPP;
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}
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#endif
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#endif /* _BPF_NETNS_H */
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