* [PATCH 6.3 085/431] sctp: add bpf_bypass_getsockopt proto callback
[not found] <20230709111451.101012554@linuxfoundation.org>
@ 2023-07-09 11:10 ` Greg Kroah-Hartman
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From: Greg Kroah-Hartman @ 2023-07-09 11:10 UTC (permalink / raw)
To: stable
Cc: Greg Kroah-Hartman, patches, Daniel Borkmann, Christian Brauner,
Stanislav Fomichev, Neil Horman, Marcelo Ricardo Leitner,
Xin Long, linux-sctp, linux-kernel, netdev, Alexander Mikhalitsyn,
David S. Miller, Sasha Levin
From: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical•com>
[ Upstream commit 2598619e012cee5273a2821441b9a051ad931249 ]
Implement ->bpf_bypass_getsockopt proto callback and filter out
SCTP_SOCKOPT_PEELOFF, SCTP_SOCKOPT_PEELOFF_FLAGS and SCTP_SOCKOPT_CONNECTX3
socket options from running eBPF hook on them.
SCTP_SOCKOPT_PEELOFF and SCTP_SOCKOPT_PEELOFF_FLAGS options do fd_install(),
and if BPF_CGROUP_RUN_PROG_GETSOCKOPT hook returns an error after success of
the original handler sctp_getsockopt(...), userspace will receive an error
from getsockopt syscall and will be not aware that fd was successfully
installed into a fdtable.
As pointed by Marcelo Ricardo Leitner it seems reasonable to skip
bpf getsockopt hook for SCTP_SOCKOPT_CONNECTX3 sockopt too.
Because internaly, it triggers connect() and if error is masked
then userspace will be confused.
This patch was born as a result of discussion around a new SCM_PIDFD interface:
https://lore.kernel.org/all/20230413133355.350571-3-aleksandr.mikhalitsyn@canonical.com/
Fixes: 0d01da6afc54 ("bpf: implement getsockopt and setsockopt hooks")
Cc: Daniel Borkmann <daniel@iogearbox•net>
Cc: Christian Brauner <brauner@kernel•org>
Cc: Stanislav Fomichev <sdf@google•com>
Cc: Neil Horman <nhorman@tuxdriver•com>
Cc: Marcelo Ricardo Leitner <marcelo.leitner@gmail•com>
Cc: Xin Long <lucien.xin@gmail•com>
Cc: linux-sctp@vger•kernel.org
Cc: linux-kernel@vger•kernel.org
Cc: netdev@vger•kernel.org
Suggested-by: Stanislav Fomichev <sdf@google•com>
Acked-by: Stanislav Fomichev <sdf@google•com>
Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical•com>
Acked-by: Xin Long <lucien.xin@gmail•com>
Signed-off-by: David S. Miller <davem@davemloft•net>
Signed-off-by: Sasha Levin <sashal@kernel•org>
---
net/sctp/socket.c | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 218e0982c3707..0932cbf568ee9 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -8280,6 +8280,22 @@ static int sctp_getsockopt(struct sock *sk, int level, int optname,
return retval;
}
+static bool sctp_bpf_bypass_getsockopt(int level, int optname)
+{
+ if (level == SOL_SCTP) {
+ switch (optname) {
+ case SCTP_SOCKOPT_PEELOFF:
+ case SCTP_SOCKOPT_PEELOFF_FLAGS:
+ case SCTP_SOCKOPT_CONNECTX3:
+ return true;
+ default:
+ return false;
+ }
+ }
+
+ return false;
+}
+
static int sctp_hash(struct sock *sk)
{
/* STUB */
@@ -9649,6 +9665,7 @@ struct proto sctp_prot = {
.shutdown = sctp_shutdown,
.setsockopt = sctp_setsockopt,
.getsockopt = sctp_getsockopt,
+ .bpf_bypass_getsockopt = sctp_bpf_bypass_getsockopt,
.sendmsg = sctp_sendmsg,
.recvmsg = sctp_recvmsg,
.bind = sctp_bind,
@@ -9704,6 +9721,7 @@ struct proto sctpv6_prot = {
.shutdown = sctp_shutdown,
.setsockopt = sctp_setsockopt,
.getsockopt = sctp_getsockopt,
+ .bpf_bypass_getsockopt = sctp_bpf_bypass_getsockopt,
.sendmsg = sctp_sendmsg,
.recvmsg = sctp_recvmsg,
.bind = sctp_bind,
--
2.39.2
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