[PATCH bpf-next v2 3/4] selftests/bpf: Correctly handle optlen > 4096

[Stanislav Fomichev <sdf@xxxxxxxxxx>]

Even though it's not relevant in selftests, the people
might still copy-paste from them. So let's take care
of optlen > 4096 cases explicitly.

Signed-off-by: Stanislav Fomichev <sdf@xxxxxxxxxx>
---
 .../progs/cgroup_getset_retval_getsockopt.c   | 12 +++++++++
 .../progs/cgroup_getset_retval_setsockopt.c   | 16 ++++++++++++
 .../selftests/bpf/progs/sockopt_inherit.c     | 16 ++++++++++--
 .../selftests/bpf/progs/sockopt_multi.c       | 24 +++++++++++++++---
 .../selftests/bpf/progs/sockopt_qos_to_cc.c   |  8 +++++-
 .../testing/selftests/bpf/progs/sockopt_sk.c  | 25 +++++++++++++------
 6 files changed, 88 insertions(+), 13 deletions(-)

diff --git a/tools/testing/selftests/bpf/progs/cgroup_getset_retval_getsockopt.c b/tools/testing/selftests/bpf/progs/cgroup_getset_retval_getsockopt.c
index b2a409e6382a..b66454886cc4 100644
--- a/tools/testing/selftests/bpf/progs/cgroup_getset_retval_getsockopt.c
+++ b/tools/testing/selftests/bpf/progs/cgroup_getset_retval_getsockopt.c
@@ -20,6 +20,10 @@ int get_retval(struct bpf_sockopt *ctx)
 	ctx_retval_value = ctx->retval;
 	__sync_fetch_and_add(&invocations, 1);
 
+	/* optval larger than PAGE_SIZE use kernel's buffer. */
+	if (ctx->optlen > 4096)
+		ctx->optlen = 0;
+
 	return 1;
 }
 
@@ -31,6 +35,10 @@ int set_eisconn(struct bpf_sockopt *ctx)
 	if (bpf_set_retval(-EISCONN))
 		assertion_error = 1;
 
+	/* optval larger than PAGE_SIZE use kernel's buffer. */
+	if (ctx->optlen > 4096)
+		ctx->optlen = 0;
+
 	return 1;
 }
 
@@ -41,5 +49,9 @@ int clear_retval(struct bpf_sockopt *ctx)
 
 	ctx->retval = 0;
 
+	/* optval larger than PAGE_SIZE use kernel's buffer. */
+	if (ctx->optlen > 4096)
+		ctx->optlen = 0;
+
 	return 1;
 }
diff --git a/tools/testing/selftests/bpf/progs/cgroup_getset_retval_setsockopt.c b/tools/testing/selftests/bpf/progs/cgroup_getset_retval_setsockopt.c
index d6e5903e06ba..68fce0311771 100644
--- a/tools/testing/selftests/bpf/progs/cgroup_getset_retval_setsockopt.c
+++ b/tools/testing/selftests/bpf/progs/cgroup_getset_retval_setsockopt.c
@@ -18,6 +18,10 @@ int get_retval(struct bpf_sockopt *ctx)
 	retval_value = bpf_get_retval();
 	__sync_fetch_and_add(&invocations, 1);
 
+	/* optval larger than PAGE_SIZE use kernel's buffer. */
+	if (ctx->optlen > 4096)
+		ctx->optlen = 0;
+
 	return 1;
 }
 
@@ -29,6 +33,10 @@ int set_eunatch(struct bpf_sockopt *ctx)
 	if (bpf_set_retval(-EUNATCH))
 		assertion_error = 1;
 
+	/* optval larger than PAGE_SIZE use kernel's buffer. */
+	if (ctx->optlen > 4096)
+		ctx->optlen = 0;
+
 	return 0;
 }
 
@@ -40,6 +48,10 @@ int set_eisconn(struct bpf_sockopt *ctx)
 	if (bpf_set_retval(-EISCONN))
 		assertion_error = 1;
 
+	/* optval larger than PAGE_SIZE use kernel's buffer. */
+	if (ctx->optlen > 4096)
+		ctx->optlen = 0;
+
 	return 0;
 }
 
@@ -48,5 +60,9 @@ int legacy_eperm(struct bpf_sockopt *ctx)
 {
 	__sync_fetch_and_add(&invocations, 1);
 
+	/* optval larger than PAGE_SIZE use kernel's buffer. */
+	if (ctx->optlen > 4096)
+		ctx->optlen = 0;
+
 	return 0;
 }
diff --git a/tools/testing/selftests/bpf/progs/sockopt_inherit.c b/tools/testing/selftests/bpf/progs/sockopt_inherit.c
index 9fb241b97291..78e56070dbcf 100644
--- a/tools/testing/selftests/bpf/progs/sockopt_inherit.c
+++ b/tools/testing/selftests/bpf/progs/sockopt_inherit.c
@@ -55,7 +55,7 @@ int _getsockopt(struct bpf_sockopt *ctx)
 	__u8 *optval = ctx->optval;
 
 	if (ctx->level != SOL_CUSTOM)
-		return 1; /* only interested in SOL_CUSTOM */
+		goto out; /* only interested in SOL_CUSTOM */
 
 	if (optval + 1 > optval_end)
 		return 0; /* EPERM, bounds check */
@@ -70,6 +70,12 @@ int _getsockopt(struct bpf_sockopt *ctx)
 	ctx->optlen = 1;
 
 	return 1;
+
+out:
+	/* optval larger than PAGE_SIZE use kernel's buffer. */
+	if (ctx->optlen > 4096)
+		ctx->optlen = 0;
+	return 1;
 }
 
 SEC("cgroup/setsockopt")
@@ -80,7 +86,7 @@ int _setsockopt(struct bpf_sockopt *ctx)
 	__u8 *optval = ctx->optval;
 
 	if (ctx->level != SOL_CUSTOM)
-		return 1; /* only interested in SOL_CUSTOM */
+		goto out; /* only interested in SOL_CUSTOM */
 
 	if (optval + 1 > optval_end)
 		return 0; /* EPERM, bounds check */
@@ -93,4 +99,10 @@ int _setsockopt(struct bpf_sockopt *ctx)
 	ctx->optlen = -1;
 
 	return 1;
+
+out:
+	/* optval larger than PAGE_SIZE use kernel's buffer. */
+	if (ctx->optlen > 4096)
+		ctx->optlen = 0;
+	return 1;
 }
diff --git a/tools/testing/selftests/bpf/progs/sockopt_multi.c b/tools/testing/selftests/bpf/progs/sockopt_multi.c
index 177a59069dae..f645eb253c6c 100644
--- a/tools/testing/selftests/bpf/progs/sockopt_multi.c
+++ b/tools/testing/selftests/bpf/progs/sockopt_multi.c
@@ -12,7 +12,7 @@ int _getsockopt_child(struct bpf_sockopt *ctx)
 	__u8 *optval = ctx->optval;
 
 	if (ctx->level != SOL_IP || ctx->optname != IP_TOS)
-		return 1;
+		goto out;
 
 	if (optval + 1 > optval_end)
 		return 0; /* EPERM, bounds check */
@@ -26,6 +26,12 @@ int _getsockopt_child(struct bpf_sockopt *ctx)
 	ctx->optlen = 1;
 
 	return 1;
+
+out:
+	/* optval larger than PAGE_SIZE use kernel's buffer. */
+	if (ctx->optlen > 4096)
+		ctx->optlen = 0;
+	return 1;
 }
 
 SEC("cgroup/getsockopt")
@@ -35,7 +41,7 @@ int _getsockopt_parent(struct bpf_sockopt *ctx)
 	__u8 *optval = ctx->optval;
 
 	if (ctx->level != SOL_IP || ctx->optname != IP_TOS)
-		return 1;
+		goto out;
 
 	if (optval + 1 > optval_end)
 		return 0; /* EPERM, bounds check */
@@ -49,6 +55,12 @@ int _getsockopt_parent(struct bpf_sockopt *ctx)
 	ctx->optlen = 1;
 
 	return 1;
+
+out:
+	/* optval larger than PAGE_SIZE use kernel's buffer. */
+	if (ctx->optlen > 4096)
+		ctx->optlen = 0;
+	return 1;
 }
 
 SEC("cgroup/setsockopt")
@@ -58,7 +70,7 @@ int _setsockopt(struct bpf_sockopt *ctx)
 	__u8 *optval = ctx->optval;
 
 	if (ctx->level != SOL_IP || ctx->optname != IP_TOS)
-		return 1;
+		goto out;
 
 	if (optval + 1 > optval_end)
 		return 0; /* EPERM, bounds check */
@@ -67,4 +79,10 @@ int _setsockopt(struct bpf_sockopt *ctx)
 	ctx->optlen = 1;
 
 	return 1;
+
+out:
+	/* optval larger than PAGE_SIZE use kernel's buffer. */
+	if (ctx->optlen > 4096)
+		ctx->optlen = 0;
+	return 1;
 }
diff --git a/tools/testing/selftests/bpf/progs/sockopt_qos_to_cc.c b/tools/testing/selftests/bpf/progs/sockopt_qos_to_cc.c
index 1bce83b6e3a7..597f3e276cf7 100644
--- a/tools/testing/selftests/bpf/progs/sockopt_qos_to_cc.c
+++ b/tools/testing/selftests/bpf/progs/sockopt_qos_to_cc.c
@@ -19,7 +19,7 @@ int sockopt_qos_to_cc(struct bpf_sockopt *ctx)
 	char cc_cubic[TCP_CA_NAME_MAX] = "cubic";
 
 	if (ctx->level != SOL_IPV6 || ctx->optname != IPV6_TCLASS)
-		return 1;
+		goto out;
 
 	if (optval + 1 > optval_end)
 		return 0; /* EPERM, bounds check */
@@ -36,4 +36,10 @@ int sockopt_qos_to_cc(struct bpf_sockopt *ctx)
 			return 0;
 	}
 	return 1;
+
+out:
+	/* optval larger than PAGE_SIZE use kernel's buffer. */
+	if (ctx->optlen > 4096)
+		ctx->optlen = 0;
+	return 1;
 }
diff --git a/tools/testing/selftests/bpf/progs/sockopt_sk.c b/tools/testing/selftests/bpf/progs/sockopt_sk.c
index fe1df4cd206e..e1aed858c208 100644
--- a/tools/testing/selftests/bpf/progs/sockopt_sk.c
+++ b/tools/testing/selftests/bpf/progs/sockopt_sk.c
@@ -37,7 +37,7 @@ int _getsockopt(struct bpf_sockopt *ctx)
 	/* Bypass AF_NETLINK. */
 	sk = ctx->sk;
 	if (sk && sk->family == AF_NETLINK)
-		return 1;
+		goto out;
 
 	/* Make sure bpf_get_netns_cookie is callable.
 	 */
@@ -52,8 +52,7 @@ int _getsockopt(struct bpf_sockopt *ctx)
 		 * let next BPF program in the cgroup chain or kernel
 		 * handle it.
 		 */
-		ctx->optlen = 0; /* bypass optval>PAGE_SIZE */
-		return 1;
+		goto out;
 	}
 
 	if (ctx->level == SOL_SOCKET && ctx->optname == SO_SNDBUF) {
@@ -61,7 +60,7 @@ int _getsockopt(struct bpf_sockopt *ctx)
 		 * let next BPF program in the cgroup chain or kernel
 		 * handle it.
 		 */
-		return 1;
+		goto out;
 	}
 
 	if (ctx->level == SOL_TCP && ctx->optname == TCP_CONGESTION) {
@@ -69,7 +68,7 @@ int _getsockopt(struct bpf_sockopt *ctx)
 		 * let next BPF program in the cgroup chain or kernel
 		 * handle it.
 		 */
-		return 1;
+		goto out;
 	}
 
 	if (ctx->level == SOL_TCP && ctx->optname == TCP_ZEROCOPY_RECEIVE) {
@@ -85,7 +84,7 @@ int _getsockopt(struct bpf_sockopt *ctx)
 		if (((struct tcp_zerocopy_receive *)optval)->address != 0)
 			return 0; /* unexpected data */
 
-		return 1;
+		goto out;
 	}
 
 	if (ctx->level == SOL_IP && ctx->optname == IP_FREEBIND) {
@@ -129,6 +128,12 @@ int _getsockopt(struct bpf_sockopt *ctx)
 	ctx->optlen = 1;
 
 	return 1;
+
+out:
+	/* optval larger than PAGE_SIZE use kernel's buffer. */
+	if (ctx->optlen > 4096)
+		ctx->optlen = 0;
+	return 1;
 }
 
 SEC("cgroup/setsockopt")
@@ -142,7 +147,7 @@ int _setsockopt(struct bpf_sockopt *ctx)
 	/* Bypass AF_NETLINK. */
 	sk = ctx->sk;
 	if (sk && sk->family == AF_NETLINK)
-		return 1;
+		goto out;
 
 	/* Make sure bpf_get_netns_cookie is callable.
 	 */
@@ -224,4 +229,10 @@ int _setsockopt(struct bpf_sockopt *ctx)
 			   */
 
 	return 1;
+
+out:
+	/* optval larger than PAGE_SIZE use kernel's buffer. */
+	if (ctx->optlen > 4096)
+		ctx->optlen = 0;
+	return 1;
 }
-- 
2.40.1.495.gc816e09b53d-goog