Splicing to SOCK_RAW sockets may set MSG_SPLICE_PAGES, but in such a case,
__ip_append_data() will call skb_splice_from_iter() to access the 'from'
data, assuming it to point to a msghdr struct with an iter, instead of
using the provided getfrag function to access it.
In the case of raw_sendmsg(), however, this is not the case and 'from' will
point to a raw_frag_vec struct and raw_getfrag() will be the frag-getting
function. A similar issue may occur with rawv6_sendmsg().
Fix this by ignoring MSG_SPLICE_PAGES if getfrag != ip_generic_getfrag as
ip_generic_getfrag() expects "from" to be a msghdr*, but the other getfrags
don't. Note that this will prevent MSG_SPLICE_PAGES from being effective
for udplite.
This likely affects ping sockets too. udplite looks like it should be okay
as it expects "from" to be a msghdr.
Signed-off-by: David Howells <[email protected]>
Reported-by: [email protected]
Link: https://lore.kernel.org/r/[email protected]/
Fixes: 2dc334f1a63a ("splice, net: Use sendmsg(MSG_SPLICE_PAGES) rather than ->sendpage()")
Tested-by: [email protected]
cc: Willem de Bruijn <[email protected]>
cc: David Ahern <[email protected]>
cc: "David S. Miller" <[email protected]>
cc: Eric Dumazet <[email protected]>
cc: Jakub Kicinski <[email protected]>
cc: Paolo Abeni <[email protected]>
cc: Jens Axboe <[email protected]>
cc: Matthew Wilcox <[email protected]>
cc: [email protected]
---
net/ipv4/ip_output.c | 3 ++-
net/ipv6/ip6_output.c | 3 ++-
2 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 244fb9365d87..4b39ea99f00b 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -1040,7 +1040,8 @@ static int __ip_append_data(struct sock *sk,
} else if ((flags & MSG_SPLICE_PAGES) && length) {
if (inet->hdrincl)
return -EPERM;
- if (rt->dst.dev->features & NETIF_F_SG)
+ if (rt->dst.dev->features & NETIF_F_SG &&
+ getfrag == ip_generic_getfrag)
/* We need an empty buffer to attach stuff to */
paged = true;
else
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index c722cb881b2d..dd845139882c 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1592,7 +1592,8 @@ static int __ip6_append_data(struct sock *sk,
} else if ((flags & MSG_SPLICE_PAGES) && length) {
if (inet_sk(sk)->hdrincl)
return -EPERM;
- if (rt->dst.dev->features & NETIF_F_SG)
+ if (rt->dst.dev->features & NETIF_F_SG &&
+ getfrag == ip_generic_getfrag)
/* We need an empty buffer to attach stuff to */
paged = true;
else
On Wed, 14 Jun 2023 09:04:16 +0100 David Howells wrote:
> Splicing to SOCK_RAW sockets may set MSG_SPLICE_PAGES, but in such a case,
> __ip_append_data() will call skb_splice_from_iter() to access the 'from'
> data, assuming it to point to a msghdr struct with an iter, instead of
> using the provided getfrag function to access it.
>
> In the case of raw_sendmsg(), however, this is not the case and 'from' will
> point to a raw_frag_vec struct and raw_getfrag() will be the frag-getting
> function. A similar issue may occur with rawv6_sendmsg().
>
> Fix this by ignoring MSG_SPLICE_PAGES if getfrag != ip_generic_getfrag as
> ip_generic_getfrag() expects "from" to be a msghdr*, but the other getfrags
> don't. Note that this will prevent MSG_SPLICE_PAGES from being effective
> for udplite.
>
> This likely affects ping sockets too. udplite looks like it should be okay
> as it expects "from" to be a msghdr.
Willem, looks good?
On Fri, Jun 16, 2023 at 7:23 AM Jakub Kicinski <[email protected]> wrote:
>
> On Wed, 14 Jun 2023 09:04:16 +0100 David Howells wrote:
> > Splicing to SOCK_RAW sockets may set MSG_SPLICE_PAGES, but in such a case,
> > __ip_append_data() will call skb_splice_from_iter() to access the 'from'
> > data, assuming it to point to a msghdr struct with an iter, instead of
> > using the provided getfrag function to access it.
> >
> > In the case of raw_sendmsg(), however, this is not the case and 'from' will
> > point to a raw_frag_vec struct and raw_getfrag() will be the frag-getting
> > function. A similar issue may occur with rawv6_sendmsg().
> >
> > Fix this by ignoring MSG_SPLICE_PAGES if getfrag != ip_generic_getfrag as
> > ip_generic_getfrag() expects "from" to be a msghdr*, but the other getfrags
> > don't. Note that this will prevent MSG_SPLICE_PAGES from being effective
> > for udplite.
> >
> > This likely affects ping sockets too. udplite looks like it should be okay
> > as it expects "from" to be a msghdr.
>
> Willem, looks good?
Reviewed-by: Willem de Bruijn <[email protected]>
Disabling splicing if not ip_generic_getfrag sounds great to me.
Willem de Bruijn <[email protected]> wrote:
> Disabling splicing if not ip_generic_getfrag sounds great to me.
I have a patch in the works that passes msghdr through getfrag that allows
this to work if we definitely want to splice into raw and icmp sockets.
David
Hello:
This patch was applied to netdev/net-next.git (main)
by Jakub Kicinski <[email protected]>:
On Wed, 14 Jun 2023 09:04:16 +0100 you wrote:
> Splicing to SOCK_RAW sockets may set MSG_SPLICE_PAGES, but in such a case,
> __ip_append_data() will call skb_splice_from_iter() to access the 'from'
> data, assuming it to point to a msghdr struct with an iter, instead of
> using the provided getfrag function to access it.
>
> In the case of raw_sendmsg(), however, this is not the case and 'from' will
> point to a raw_frag_vec struct and raw_getfrag() will be the frag-getting
> function. A similar issue may occur with rawv6_sendmsg().
>
> [...]
Here is the summary with links:
- [net-next] ip, ip6: Fix splice to raw and ping sockets
https://git.kernel.org/netdev/net-next/c/5a6f6873606e
You are awesome, thank you!
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