| Message ID | 20240216234356.32243-2-justin.iurman@uliege.be (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | ioam6: fix write to cloned skb's | expand |
On Sat, 2024-02-17 at 00:43 +0100, Justin Iurman wrote: > ioam6_fill_trace_data() writes inside the skb payload without ensuring > it's writeable (e.g., not cloned). This function is called both from the > input and output path. The output path (ioam6_iptunnel) already does the > check. This commit provides a fix for the input path, inside > ipv6_hop_ioam(). > > Fixes: 9ee11f0fff20 ("ipv6: ioam: Data plane support for Pre-allocated Trace ") > Reported-by: Paolo Abeni <pabeni@redhat.com> > Signed-off-by: Justin Iurman <justin.iurman@uliege.be> > --- > net/ipv6/exthdrs.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/net/ipv6/exthdrs.c b/net/ipv6/exthdrs.c > index 4952ae792450..f68e5faab3aa 100644 > --- a/net/ipv6/exthdrs.c > +++ b/net/ipv6/exthdrs.c > @@ -943,6 +943,14 @@ static bool ipv6_hop_ioam(struct sk_buff *skb, int optoff) > if (!skb_valid_dst(skb)) > ip6_route_input(skb); > > + if (skb_cloned(skb)) { > + if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) > + goto drop; My personal preference would be for using skb_ensure_writable() here, with write_len == optoff + hdr->opt_len. > + > + hdr = (struct ioam6_hdr *)(skb_network_header(skb) + optoff); > + trace = (struct ioam6_trace_hdr *)((u8 *)hdr + sizeof(*hdr)); Note that this can potentially change the network header ptr and the caller - ip6_parse_tlv() - has cached such value in 'nh'. You also need to update ip6_parse_tlv() to reload such pointer. Side note: a bunch of self-tests are apparently stuck after this series. I think it's an unrelated problem. I'll try to have a better look. Cheers, Paolo
On 2/19/24 10:05, Paolo Abeni wrote: > On Sat, 2024-02-17 at 00:43 +0100, Justin Iurman wrote: >> ioam6_fill_trace_data() writes inside the skb payload without ensuring >> it's writeable (e.g., not cloned). This function is called both from the >> input and output path. The output path (ioam6_iptunnel) already does the >> check. This commit provides a fix for the input path, inside >> ipv6_hop_ioam(). >> >> Fixes: 9ee11f0fff20 ("ipv6: ioam: Data plane support for Pre-allocated Trace ") >> Reported-by: Paolo Abeni <pabeni@redhat.com> >> Signed-off-by: Justin Iurman <justin.iurman@uliege.be> >> --- >> net/ipv6/exthdrs.c | 8 ++++++++ >> 1 file changed, 8 insertions(+) >> >> diff --git a/net/ipv6/exthdrs.c b/net/ipv6/exthdrs.c >> index 4952ae792450..f68e5faab3aa 100644 >> --- a/net/ipv6/exthdrs.c >> +++ b/net/ipv6/exthdrs.c >> @@ -943,6 +943,14 @@ static bool ipv6_hop_ioam(struct sk_buff *skb, int optoff) >> if (!skb_valid_dst(skb)) >> ip6_route_input(skb); >> >> + if (skb_cloned(skb)) { >> + if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) >> + goto drop; > > My personal preference would be for using skb_ensure_writable() here, > with write_len == optoff + hdr->opt_len. OK, will do! >> + >> + hdr = (struct ioam6_hdr *)(skb_network_header(skb) + optoff); >> + trace = (struct ioam6_trace_hdr *)((u8 *)hdr + sizeof(*hdr)); > > Note that this can potentially change the network header ptr and the > caller - ip6_parse_tlv() - has cached such value in 'nh'. You also need > to update ip6_parse_tlv() to reload such pointer. +1, I completely missed it, thanks! > Side note: a bunch of self-tests are apparently stuck after this > series. I think it's an unrelated problem. I'll try to have a better > look. Can you share the config to observe such behavior? I'll try to investigate too. > Cheers, > > Paolo >
diff --git a/net/ipv6/exthdrs.c b/net/ipv6/exthdrs.c index 4952ae792450..f68e5faab3aa 100644 --- a/net/ipv6/exthdrs.c +++ b/net/ipv6/exthdrs.c @@ -943,6 +943,14 @@ static bool ipv6_hop_ioam(struct sk_buff *skb, int optoff) if (!skb_valid_dst(skb)) ip6_route_input(skb); + if (skb_cloned(skb)) { + if (pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) + goto drop; + + hdr = (struct ioam6_hdr *)(skb_network_header(skb) + optoff); + trace = (struct ioam6_trace_hdr *)((u8 *)hdr + sizeof(*hdr)); + } + ioam6_fill_trace_data(skb, ns, trace, true); break; default:
ioam6_fill_trace_data() writes inside the skb payload without ensuring it's writeable (e.g., not cloned). This function is called both from the input and output path. The output path (ioam6_iptunnel) already does the check. This commit provides a fix for the input path, inside ipv6_hop_ioam(). Fixes: 9ee11f0fff20 ("ipv6: ioam: Data plane support for Pre-allocated Trace ") Reported-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: Justin Iurman <justin.iurman@uliege.be> --- net/ipv6/exthdrs.c | 8 ++++++++ 1 file changed, 8 insertions(+)