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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 /kernel/bpf | |
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 'kernel/bpf')
-rw-r--r-- | kernel/bpf/devmap.c | 17 |
1 files changed, 4 insertions, 13 deletions
diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c index bfdff2faf5cb..0cbb72cdaf63 100644 --- a/kernel/bpf/devmap.c +++ b/kernel/bpf/devmap.c @@ -60,15 +60,6 @@ struct xdp_dev_bulk_queue { unsigned int count; }; -/* DEVMAP values */ -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; -}; - struct bpf_dtab_netdev { struct net_device *dev; /* must be first member, due to tracepoint */ struct hlist_node index_hlist; @@ -619,7 +610,7 @@ static struct bpf_dtab_netdev *__dev_map_alloc_node(struct net *net, if (!dev->dev) goto err_out; - if (val->bpf_prog.fd >= 0) { + if (val->bpf_prog.fd > 0) { prog = bpf_prog_get_type_dev(val->bpf_prog.fd, BPF_PROG_TYPE_XDP, false); if (IS_ERR(prog)) @@ -653,8 +644,8 @@ static int __dev_map_update_elem(struct net *net, struct bpf_map *map, void *key, void *value, u64 map_flags) { struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map); - struct bpf_devmap_val val = { .bpf_prog.fd = -1 }; struct bpf_dtab_netdev *dev, *old_dev; + struct bpf_devmap_val val = {}; u32 i = *(u32 *)key; if (unlikely(map_flags > BPF_EXIST)) @@ -670,7 +661,7 @@ static int __dev_map_update_elem(struct net *net, struct bpf_map *map, if (!val.ifindex) { dev = NULL; /* can not specify fd if ifindex is 0 */ - if (val.bpf_prog.fd != -1) + if (val.bpf_prog.fd > 0) return -EINVAL; } else { dev = __dev_map_alloc_node(net, dtab, &val, i); @@ -700,8 +691,8 @@ static int __dev_map_hash_update_elem(struct net *net, struct bpf_map *map, void *key, void *value, u64 map_flags) { struct bpf_dtab *dtab = container_of(map, struct bpf_dtab, map); - struct bpf_devmap_val val = { .bpf_prog.fd = -1 }; struct bpf_dtab_netdev *dev, *old_dev; + struct bpf_devmap_val val = {}; u32 idx = *(u32 *)key; unsigned long flags; int err = -EEXIST; |