| Message ID | 7741c46545c6ef02e70c80a9b32814b22d9616b3.1628264975.git.gnault@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | [net] bareudp: Fix invalid read beyond skb's linear data | expand |
On Fri, Aug 06, 2021 at 04:22:34PM -0700, Jakub Kicinski wrote: > On Fri, 6 Aug 2021 17:52:06 +0200 Guillaume Nault wrote: > > Data beyond the UDP header might not be part of the skb's linear data. > > Use skb_copy_bits() instead of direct access to skb->data+X, so that > > we read the correct bytes even on a fragmented skb. > > > > Fixes: 4b5f67232d95 ("net: Special handling for IP & MPLS.") > > Signed-off-by: Guillaume Nault <gnault@redhat.com> > > --- > > drivers/net/bareudp.c | 16 +++++++++++----- > > 1 file changed, 11 insertions(+), 5 deletions(-) > > > > diff --git a/drivers/net/bareudp.c b/drivers/net/bareudp.c > > index a7ee0af1af90..54e321a695ce 100644 > > --- a/drivers/net/bareudp.c > > +++ b/drivers/net/bareudp.c > > @@ -71,12 +71,18 @@ static int bareudp_udp_encap_recv(struct sock *sk, struct sk_buff *skb) > > family = AF_INET6; > > > > if (bareudp->ethertype == htons(ETH_P_IP)) { > > - struct iphdr *iphdr; > > + __u8 ipversion; > > > > - iphdr = (struct iphdr *)(skb->data + BAREUDP_BASE_HLEN); > > - if (iphdr->version == 4) { > > - proto = bareudp->ethertype; > > - } else if (bareudp->multi_proto_mode && (iphdr->version == 6)) { > > + if (skb_copy_bits(skb, BAREUDP_BASE_HLEN, &ipversion, > > + sizeof(ipversion))) { > > No preference just curious - could skb_header_pointer() be better suited? I have no preference either. I just used skb_copy_bits() because it didn't seem useful to get a pointer to the buffer (just to read one byte of data). But I don't mind reposting with skb_header_pointer() if anyone prefers that solution.
On Sun, 8 Aug 2021 18:16:25 +0200 Guillaume Nault wrote: > On Fri, Aug 06, 2021 at 04:22:34PM -0700, Jakub Kicinski wrote: > > On Fri, 6 Aug 2021 17:52:06 +0200 Guillaume Nault wrote: > > > Data beyond the UDP header might not be part of the skb's linear data. > > > Use skb_copy_bits() instead of direct access to skb->data+X, so that > > > we read the correct bytes even on a fragmented skb. > > > > > > Fixes: 4b5f67232d95 ("net: Special handling for IP & MPLS.") > > > Signed-off-by: Guillaume Nault <gnault@redhat.com> > > > --- > > > drivers/net/bareudp.c | 16 +++++++++++----- > > > 1 file changed, 11 insertions(+), 5 deletions(-) > > > > > > diff --git a/drivers/net/bareudp.c b/drivers/net/bareudp.c > > > index a7ee0af1af90..54e321a695ce 100644 > > > --- a/drivers/net/bareudp.c > > > +++ b/drivers/net/bareudp.c > > > @@ -71,12 +71,18 @@ static int bareudp_udp_encap_recv(struct sock *sk, struct sk_buff *skb) > > > family = AF_INET6; > > > > > > if (bareudp->ethertype == htons(ETH_P_IP)) { > > > - struct iphdr *iphdr; > > > + __u8 ipversion; > > > > > > - iphdr = (struct iphdr *)(skb->data + BAREUDP_BASE_HLEN); > > > - if (iphdr->version == 4) { > > > - proto = bareudp->ethertype; > > > - } else if (bareudp->multi_proto_mode && (iphdr->version == 6)) { > > > + if (skb_copy_bits(skb, BAREUDP_BASE_HLEN, &ipversion, > > > + sizeof(ipversion))) { > > > > No preference just curious - could skb_header_pointer() be better suited? > > I have no preference either. I just used skb_copy_bits() because it > didn't seem useful to get a pointer to the buffer (just to read one > byte of data). Right, the advantage would be in the "fast" case of skb_header_pointer() being inlined. > But I don't mind reposting with skb_header_pointer() if anyone prefers > that solution.
Hello: This patch was applied to netdev/net.git (refs/heads/master): On Fri, 6 Aug 2021 17:52:06 +0200 you wrote: > Data beyond the UDP header might not be part of the skb's linear data. > Use skb_copy_bits() instead of direct access to skb->data+X, so that > we read the correct bytes even on a fragmented skb. > > Fixes: 4b5f67232d95 ("net: Special handling for IP & MPLS.") > Signed-off-by: Guillaume Nault <gnault@redhat.com> > > [...] Here is the summary with links: - [net] bareudp: Fix invalid read beyond skb's linear data https://git.kernel.org/netdev/net/c/143a8526ab5f You are awesome, thank you! -- Deet-doot-dot, I am a bot. https://korg.docs.kernel.org/patchwork/pwbot.html
On Mon, Aug 09, 2021 at 09:19:18AM -0700, Jakub Kicinski wrote: > On Sun, 8 Aug 2021 18:16:25 +0200 Guillaume Nault wrote: > > On Fri, Aug 06, 2021 at 04:22:34PM -0700, Jakub Kicinski wrote: > > > On Fri, 6 Aug 2021 17:52:06 +0200 Guillaume Nault wrote: > > > > Data beyond the UDP header might not be part of the skb's linear data. > > > > Use skb_copy_bits() instead of direct access to skb->data+X, so that > > > > we read the correct bytes even on a fragmented skb. > > > > > > > > Fixes: 4b5f67232d95 ("net: Special handling for IP & MPLS.") > > > > Signed-off-by: Guillaume Nault <gnault@redhat.com> > > > > --- > > > > drivers/net/bareudp.c | 16 +++++++++++----- > > > > 1 file changed, 11 insertions(+), 5 deletions(-) > > > > > > > > diff --git a/drivers/net/bareudp.c b/drivers/net/bareudp.c > > > > index a7ee0af1af90..54e321a695ce 100644 > > > > --- a/drivers/net/bareudp.c > > > > +++ b/drivers/net/bareudp.c > > > > @@ -71,12 +71,18 @@ static int bareudp_udp_encap_recv(struct sock *sk, struct sk_buff *skb) > > > > family = AF_INET6; > > > > > > > > if (bareudp->ethertype == htons(ETH_P_IP)) { > > > > - struct iphdr *iphdr; > > > > + __u8 ipversion; > > > > > > > > - iphdr = (struct iphdr *)(skb->data + BAREUDP_BASE_HLEN); > > > > - if (iphdr->version == 4) { > > > > - proto = bareudp->ethertype; > > > > - } else if (bareudp->multi_proto_mode && (iphdr->version == 6)) { > > > > + if (skb_copy_bits(skb, BAREUDP_BASE_HLEN, &ipversion, > > > > + sizeof(ipversion))) { > > > > > > No preference just curious - could skb_header_pointer() be better suited? > > > > I have no preference either. I just used skb_copy_bits() because it > > didn't seem useful to get a pointer to the buffer (just to read one > > byte of data). > > Right, the advantage would be in the "fast" case of skb_header_pointer() > being inlined. Yes indeed. The problem was found because of some automated functionnal tests, not because of any practical use cases. So I didn't consider the possible performance differences. I see that you've applied the patch as is already. I can switch to skb_header_pointer() in the future, if anyone sees any practical benefit for it. Thanks for the review.
diff --git a/drivers/net/bareudp.c b/drivers/net/bareudp.c index a7ee0af1af90..54e321a695ce 100644 --- a/drivers/net/bareudp.c +++ b/drivers/net/bareudp.c @@ -71,12 +71,18 @@ static int bareudp_udp_encap_recv(struct sock *sk, struct sk_buff *skb) family = AF_INET6; if (bareudp->ethertype == htons(ETH_P_IP)) { - struct iphdr *iphdr; + __u8 ipversion; - iphdr = (struct iphdr *)(skb->data + BAREUDP_BASE_HLEN); - if (iphdr->version == 4) { - proto = bareudp->ethertype; - } else if (bareudp->multi_proto_mode && (iphdr->version == 6)) { + if (skb_copy_bits(skb, BAREUDP_BASE_HLEN, &ipversion, + sizeof(ipversion))) { + bareudp->dev->stats.rx_dropped++; + goto drop; + } + ipversion >>= 4; + + if (ipversion == 4) { + proto = htons(ETH_P_IP); + } else if (ipversion == 6 && bareudp->multi_proto_mode) { proto = htons(ETH_P_IPV6); } else { bareudp->dev->stats.rx_dropped++;
Data beyond the UDP header might not be part of the skb's linear data. Use skb_copy_bits() instead of direct access to skb->data+X, so that we read the correct bytes even on a fragmented skb. Fixes: 4b5f67232d95 ("net: Special handling for IP & MPLS.") Signed-off-by: Guillaume Nault <gnault@redhat.com> --- drivers/net/bareudp.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-)