diff options
| author | Toke Høiland-Jørgensen <toke@redhat.com> | 2024-09-20 14:56:24 +0200 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2024-10-01 21:40:12 +0200 |
| commit | 09d88791c7cd888d5195c84733caf9183dcfbd16 (patch) | |
| tree | 36db622740d93e9437fb97d49cc371b795550543 /include/uapi | |
| parent | a41b3828ec056a631ad22413d4560017fed5c3bd (diff) | |
bpf: Make sure internal and UAPI bpf_redirect flags don't overlap
The bpf_redirect_info is shared between the SKB and XDP redirect paths,
and the two paths use the same numeric flag values in the ri->flags
field (specifically, BPF_F_BROADCAST == BPF_F_NEXTHOP). This means that
if skb bpf_redirect_neigh() is used with a non-NULL params argument and,
subsequently, an XDP redirect is performed using the same
bpf_redirect_info struct, the XDP path will get confused and end up
crashing, which syzbot managed to trigger.
With the stack-allocated bpf_redirect_info, the structure is no longer
shared between the SKB and XDP paths, so the crash doesn't happen
anymore. However, different code paths using identically-numbered flag
values in the same struct field still seems like a bit of a mess, so
this patch cleans that up by moving the flag definitions together and
redefining the three flags in BPF_F_REDIRECT_INTERNAL to not overlap
with the flags used for XDP. It also adds a BUILD_BUG_ON() check to make
sure the overlap is not re-introduced by mistake.
Fixes: e624d4ed4aa8 ("xdp: Extend xdp_redirect_map with broadcast support")
Reported-by: syzbot+cca39e6e84a367a7e6f6@syzkaller.appspotmail.com
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Closes: https://syzkaller.appspot.com/bug?extid=cca39e6e84a367a7e6f6
Link: https://lore.kernel.org/bpf/20240920125625.59465-1-toke@redhat.com
Diffstat (limited to 'include/uapi')
| -rw-r--r-- | include/uapi/linux/bpf.h | 13 |
1 files changed, 5 insertions, 8 deletions
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index c6cd7c7aeeee..e8241b320c6d 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -6047,11 +6047,6 @@ enum { BPF_F_MARK_ENFORCE = (1ULL << 6), }; -/* BPF_FUNC_clone_redirect and BPF_FUNC_redirect flags. */ -enum { - BPF_F_INGRESS = (1ULL << 0), -}; - /* BPF_FUNC_skb_set_tunnel_key and BPF_FUNC_skb_get_tunnel_key flags. */ enum { BPF_F_TUNINFO_IPV6 = (1ULL << 0), @@ -6198,10 +6193,12 @@ enum { BPF_F_BPRM_SECUREEXEC = (1ULL << 0), }; -/* Flags for bpf_redirect_map helper */ +/* Flags for bpf_redirect and bpf_redirect_map helpers */ enum { - BPF_F_BROADCAST = (1ULL << 3), - BPF_F_EXCLUDE_INGRESS = (1ULL << 4), + BPF_F_INGRESS = (1ULL << 0), /* used for skb path */ + BPF_F_BROADCAST = (1ULL << 3), /* used for XDP path */ + BPF_F_EXCLUDE_INGRESS = (1ULL << 4), /* used for XDP path */ +#define BPF_F_REDIRECT_FLAGS (BPF_F_INGRESS | BPF_F_BROADCAST | BPF_F_EXCLUDE_INGRESS) }; #define __bpf_md_ptr(type, name) \ |