diff options
author | Daniel Borkmann <daniel@iogearbox.net> | 2024-09-13 22:17:50 +0300 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-10-04 17:29:23 +0300 |
commit | a634fa8e480ac2423f86311a602f6295df2c8ed0 (patch) | |
tree | 67e536cf0ef0b76145699c9f7609de9f231f7783 /net | |
parent | abf7559b4ff697714a6ca2600c16b02cfd75a2cb (diff) | |
download | linux-a634fa8e480ac2423f86311a602f6295df2c8ed0.tar.xz |
bpf: Zero former ARG_PTR_TO_{LONG,INT} args in case of error
[ Upstream commit 4b3786a6c5397dc220b1483d8e2f4867743e966f ]
For all non-tracing helpers which formerly had ARG_PTR_TO_{LONG,INT} as input
arguments, zero the value for the case of an error as otherwise it could leak
memory. For tracing, it is not needed given CAP_PERFMON can already read all
kernel memory anyway hence bpf_get_func_arg() and bpf_get_func_ret() is skipped
in here.
Also, the MTU helpers mtu_len pointer value is being written but also read.
Technically, the MEM_UNINIT should not be there in order to always force init.
Removing MEM_UNINIT needs more verifier rework though: MEM_UNINIT right now
implies two things actually: i) write into memory, ii) memory does not have
to be initialized. If we lift MEM_UNINIT, it then becomes: i) read into memory,
ii) memory must be initialized. This means that for bpf_*_check_mtu() we're
readding the issue we're trying to fix, that is, it would then be able to
write back into things like .rodata BPF maps. Follow-up work will rework the
MEM_UNINIT semantics such that the intent can be better expressed. For now
just clear the *mtu_len on error path which can be lifted later again.
Fixes: 8a67f2de9b1d ("bpf: expose bpf_strtol and bpf_strtoul to all program types")
Fixes: d7a4cb9b6705 ("bpf: Introduce bpf_strtol and bpf_strtoul helpers")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/e5edd241-59e7-5e39-0ee5-a51e31b6840a@iogearbox.net
Link: https://lore.kernel.org/r/20240913191754.13290-5-daniel@iogearbox.net
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'net')
-rw-r--r-- | net/core/filter.c | 44 |
1 files changed, 23 insertions, 21 deletions
diff --git a/net/core/filter.c b/net/core/filter.c index ecde9111fc95..8bfd46a070c1 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -6222,20 +6222,25 @@ BPF_CALL_5(bpf_skb_check_mtu, struct sk_buff *, skb, int ret = BPF_MTU_CHK_RET_FRAG_NEEDED; struct net_device *dev = skb->dev; int skb_len, dev_len; - int mtu; + int mtu = 0; - if (unlikely(flags & ~(BPF_MTU_CHK_SEGS))) - return -EINVAL; + if (unlikely(flags & ~(BPF_MTU_CHK_SEGS))) { + ret = -EINVAL; + goto out; + } - if (unlikely(flags & BPF_MTU_CHK_SEGS && (len_diff || *mtu_len))) - return -EINVAL; + if (unlikely(flags & BPF_MTU_CHK_SEGS && (len_diff || *mtu_len))) { + ret = -EINVAL; + goto out; + } dev = __dev_via_ifindex(dev, ifindex); - if (unlikely(!dev)) - return -ENODEV; + if (unlikely(!dev)) { + ret = -ENODEV; + goto out; + } mtu = READ_ONCE(dev->mtu); - dev_len = mtu + dev->hard_header_len; /* If set use *mtu_len as input, L3 as iph->tot_len (like fib_lookup) */ @@ -6253,15 +6258,12 @@ BPF_CALL_5(bpf_skb_check_mtu, struct sk_buff *, skb, */ if (skb_is_gso(skb)) { ret = BPF_MTU_CHK_RET_SUCCESS; - if (flags & BPF_MTU_CHK_SEGS && !skb_gso_validate_network_len(skb, mtu)) ret = BPF_MTU_CHK_RET_SEGS_TOOBIG; } out: - /* BPF verifier guarantees valid pointer */ *mtu_len = mtu; - return ret; } @@ -6271,19 +6273,21 @@ BPF_CALL_5(bpf_xdp_check_mtu, struct xdp_buff *, xdp, struct net_device *dev = xdp->rxq->dev; int xdp_len = xdp->data_end - xdp->data; int ret = BPF_MTU_CHK_RET_SUCCESS; - int mtu, dev_len; + int mtu = 0, dev_len; /* XDP variant doesn't support multi-buffer segment check (yet) */ - if (unlikely(flags)) - return -EINVAL; + if (unlikely(flags)) { + ret = -EINVAL; + goto out; + } dev = __dev_via_ifindex(dev, ifindex); - if (unlikely(!dev)) - return -ENODEV; + if (unlikely(!dev)) { + ret = -ENODEV; + goto out; + } mtu = READ_ONCE(dev->mtu); - - /* Add L2-header as dev MTU is L3 size */ dev_len = mtu + dev->hard_header_len; /* Use *mtu_len as input, L3 as iph->tot_len (like fib_lookup) */ @@ -6293,10 +6297,8 @@ BPF_CALL_5(bpf_xdp_check_mtu, struct xdp_buff *, xdp, xdp_len += len_diff; /* minus result pass check */ if (xdp_len > dev_len) ret = BPF_MTU_CHK_RET_FRAG_NEEDED; - - /* BPF verifier guarantees valid pointer */ +out: *mtu_len = mtu; - return ret; } |