From 58e7d876ffd50a309b50fbc98dfb77150156f890 Mon Sep 17 00:00:00 2001
From: Etienne Perot <eperot@google.com>
Date: Fri, 28 Aug 2026 13:28:04 -0700
Subject: [PATCH] Fix `//test/syscalls:tcp_socket_test_native` failing on newer
 kernels.

As of Linux commit 5d39580f68e6, SO_ATTACH_FILTER requires CAP_NET_ADMIN for TCP sockets.

Skip in tests if we don't have it, and update Netstack to require it too.

FUTURE_COPYBARA_INTEGRATE_REVIEW=https://github.com/google/gvisor/pull/14478 from EtiennePerot:socket-test-fix 2e2e65ee665a7d48e0358e58191d813174dac8cd
PiperOrigin-RevId: 972759993
---
 pkg/sentry/socket/netstack/netstack.go | 10 +++++++-
 test/syscalls/linux/BUILD              |  1 +
 test/syscalls/linux/tcp_socket.cc      | 32 +++++++++++++++++++++++---
 3 files changed, 39 insertions(+), 4 deletions(-)

diff --git a/pkg/sentry/socket/netstack/netstack.go b/pkg/sentry/socket/netstack/netstack.go
index de5092ee5ea..e1bdaba200d 100644
--- a/pkg/sentry/socket/netstack/netstack.go
+++ b/pkg/sentry/socket/netstack/netstack.go
@@ -36,6 +36,7 @@ import (
 
 	"golang.org/x/sys/unix"
 	"google.golang.org/protobuf/proto"
+
 	"gvisor.dev/gvisor/pkg/abi/linux"
 	"gvisor.dev/gvisor/pkg/abi/linux/errno"
 	"gvisor.dev/gvisor/pkg/context"
@@ -2151,6 +2152,14 @@ func SetSockOptSocket(t *kernel.Task, s socket.Socket, ep commonEndpoint, name i
 		})
 		return nil
 
+	case linux.SO_ATTACH_FILTER:
+		if socket.IsTCP(s) &&
+			!t.HasCapabilityIn(linux.CAP_NET_ADMIN, t.NetworkNamespace().UserNamespace()) {
+			return syserr.ErrNotPermitted
+		}
+		incrementBadSetSocketOptionMetric(t, &socketLevelSocketFieldValue, name)
+		return nil
+
 	case linux.SO_DETACH_FILTER:
 		// optval is ignored.
 		var v tcpip.SocketDetachFilterOption
@@ -2188,7 +2197,6 @@ func SetSockOptSocket(t *kernel.Task, s socket.Socket, ep commonEndpoint, name i
 		linux.SO_BSDCOMPAT,
 		linux.SO_PEERCRED,
 		linux.SO_SNDLOWAT,
-		linux.SO_ATTACH_FILTER,
 		linux.SO_PEERNAME,
 		linux.SO_TIMESTAMP,
 		linux.SO_ACCEPTCONN,
diff --git a/test/syscalls/linux/BUILD b/test/syscalls/linux/BUILD
index 5532f54770f..6fd5698f0b0 100644
--- a/test/syscalls/linux/BUILD
+++ b/test/syscalls/linux/BUILD
@@ -4480,6 +4480,7 @@ cc_binary(
     linkstatic = 1,
     malloc = "//test/util:errno_safe_allocator",
     deps = select_gtest() + [
+        "//test/util:capability_util",
         "//test/util:file_descriptor",
         "//test/util:posix_error",
         "//test/util:socket_util",
diff --git a/test/syscalls/linux/tcp_socket.cc b/test/syscalls/linux/tcp_socket.cc
index 5caa0d6f751..fd4d8163012 100644
--- a/test/syscalls/linux/tcp_socket.cc
+++ b/test/syscalls/linux/tcp_socket.cc
@@ -38,6 +38,7 @@
 #include "absl/status/statusor.h"
 #include "absl/time/clock.h"
 #include "absl/time/time.h"
+#include "test/util/capability_util.h"
 #include "test/util/file_descriptor.h"
 #include "test/util/posix_error.h"
 #include "test/util/socket_util.h"
@@ -2297,9 +2298,14 @@ TEST_P(SimpleTcpSocketTest, SetSocketAttachDetachFilter) {
       .len = std::size(code),
       .filter = code,
   };
-  ASSERT_THAT(
-      setsockopt(s.get(), SOL_SOCKET, SO_ATTACH_FILTER, &bpf, sizeof(bpf)),
-      SyscallSucceeds());
+  int ret =
+      setsockopt(s.get(), SOL_SOCKET, SO_ATTACH_FILTER, &bpf, sizeof(bpf));
+  if (ret < 0 && errno == EPERM) {
+    // Linux 5d39580f68e6 ("tcp: restrict SO_ATTACH_FILTER to priv users")
+    // requires CAP_NET_ADMIN over the socket's network namespace.
+    SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability(CAP_NET_ADMIN)));
+  }
+  ASSERT_THAT(ret, SyscallSucceeds());
 
   constexpr int val = 0;
   ASSERT_THAT(
@@ -2307,6 +2313,26 @@ TEST_P(SimpleTcpSocketTest, SetSocketAttachDetachFilter) {
       SyscallSucceeds());
 }
 
+TEST_P(SimpleTcpSocketTest, SetSocketAttachFilterWithoutNetAdmin) {
+  FileDescriptor s =
+      ASSERT_NO_ERRNO_AND_VALUE(Socket(GetParam(), SOCK_STREAM, IPPROTO_TCP));
+  struct sock_filter code[] = {{0x6, 0, 0, 0x00040000}};  // ret 0x40000
+  struct sock_fprog bpf = {
+      .len = std::size(code),
+      .filter = code,
+  };
+  AutoCapability cap(CAP_NET_ADMIN, false);
+  int ret =
+      setsockopt(s.get(), SOL_SOCKET, SO_ATTACH_FILTER, &bpf, sizeof(bpf));
+  if (!IsRunningOnGvisor() || IsRunningWithHostinet()) {
+    // Only Linux 5d39580f68e6 ("tcp: restrict SO_ATTACH_FILTER to priv
+    // users") and later requires CAP_NET_ADMIN, so this can succeed on
+    // old kernels (including with hostinet on an old kernel).
+    SKIP_IF(ret == 0);
+  }
+  EXPECT_THAT(ret, SyscallFailsWithErrno(EPERM));
+}
+
 #endif  // __linux__
 
 TEST_P(SimpleTcpSocketTest, SetSocketDetachFilterNoInstalledFilter) {