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author | Jesper Dangaard Brouer <brouer@redhat.com> | 2020-06-09 15:31:46 +0200 |
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committer | Alexei Starovoitov <ast@kernel.org> | 2020-06-09 11:36:18 -0700 |
commit | 281920b7e0b31e0a7706433ff58e7d52ac97c327 (patch) | |
tree | 64eae501b2e4edc6a07a2c530f29bb3c009e0a11 /include/uapi/linux/bpf.h | |
parent | 248e00ac47d64e153b9c50f45aad73cd61894a73 (diff) | |
download | linux-stable-281920b7e0b31e0a7706433ff58e7d52ac97c327.tar.gz linux-stable-281920b7e0b31e0a7706433ff58e7d52ac97c327.tar.bz2 linux-stable-281920b7e0b31e0a7706433ff58e7d52ac97c327.zip |
bpf: Devmap adjust uapi for attach bpf program
V2:
- Defer changing BPF-syscall to start at file-descriptor 1
- Use {} to zero initialise struct.
The recent commit fbee97feed9b ("bpf: Add support to attach bpf program to a
devmap entry"), introduced ability to attach (and run) a separate XDP
bpf_prog for each devmap entry. A bpf_prog is added via a file-descriptor.
As zero were a valid FD, not using the feature requires using value minus-1.
The UAPI is extended via tail-extending struct bpf_devmap_val and using
map->value_size to determine the feature set.
This will break older userspace applications not using the bpf_prog feature.
Consider an old userspace app that is compiled against newer kernel
uapi/bpf.h, it will not know that it need to initialise the member
bpf_prog.fd to minus-1. Thus, users will be forced to update source code to
get program running on newer kernels.
This patch remove the minus-1 checks, and have zero mean feature isn't used.
Followup patches either for kernel or libbpf should handle and avoid
returning file-descriptor zero in the first place.
Fixes: fbee97feed9b ("bpf: Add support to attach bpf program to a devmap entry")
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/159170950687.2102545.7235914718298050113.stgit@firesoul
Diffstat (limited to 'include/uapi/linux/bpf.h')
-rw-r--r-- | include/uapi/linux/bpf.h | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index c65b374a5090..19684813faae 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -3761,6 +3761,19 @@ struct xdp_md { __u32 egress_ifindex; /* txq->dev->ifindex */ }; +/* DEVMAP map-value layout + * + * The struct data-layout of map-value is a configuration interface. + * New members can only be added to the end of this structure. + */ +struct bpf_devmap_val { + __u32 ifindex; /* device index */ + union { + int fd; /* prog fd on map write */ + __u32 id; /* prog id on map read */ + } bpf_prog; +}; + enum sk_action { SK_DROP = 0, SK_PASS, |