1 files changed, 117 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/progs/sock_ops_get_sk.c b/tools/testing/selftests/bpf/progs/sock_ops_get_sk.c
new file mode 100644
index 000000000000..3a0689f8ce7c
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/sock_ops_get_sk.c
@@ -0,0 +1,117 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include "bpf_misc.h"
+
+/*
+ * Test the SOCK_OPS_GET_SK() and SOCK_OPS_GET_FIELD() macros in
+ * sock_ops_convert_ctx_access() when dst_reg == src_reg.
+ *
+ * When dst_reg == src_reg, the macros borrow a temporary register to load
+ * is_fullsock / is_locked_tcp_sock, because dst_reg holds the ctx pointer
+ * and cannot be clobbered before ctx->sk / ctx->field is read. If
+ * is_fullsock == 0 (e.g., TCP_NEW_SYN_RECV with a request_sock), the macro
+ * must still zero dst_reg so the verifier's PTR_TO_SOCKET_OR_NULL /
+ * SCALAR_VALUE type is correct at runtime. A missing clear leaves a stale
+ * ctx pointer in dst_reg that passes NULL checks (GET_SK) or leaks a kernel
+ * address as a scalar (GET_FIELD).
+ *
+ * When dst_reg != src_reg, dst_reg itself is used to load is_fullsock, so
+ * the JEQ (dst_reg == 0) naturally leaves it zeroed on the !fullsock path.
+ */
+
+int bug_detected;
+int null_seen;
+
+SEC("sockops")
+__naked void sock_ops_get_sk_same_reg(void)
+{
+	asm volatile (
+		"r7 = *(u32 *)(r1 + %[is_fullsock_off]);"
+		"r1 = *(u64 *)(r1 + %[sk_off]);"
+		"if r7 != 0 goto 2f;"
+		"if r1 == 0 goto 1f;"
+		"r1 = %[bug_detected] ll;"
+		"r2 = 1;"
+		"*(u32 *)(r1 + 0) = r2;"
+		"goto 2f;"
+	"1:"
+		"r1 = %[null_seen] ll;"
+		"r2 = 1;"
+		"*(u32 *)(r1 + 0) = r2;"
+	"2:"
+		"r0 = 1;"
+		"exit;"
+		:
+		: __imm_const(is_fullsock_off, offsetof(struct bpf_sock_ops, is_fullsock)),
+		  __imm_const(sk_off, offsetof(struct bpf_sock_ops, sk)),
+		  __imm_addr(bug_detected),
+		  __imm_addr(null_seen)
+		: __clobber_all);
+}
+
+/* SOCK_OPS_GET_FIELD: same-register, is_locked_tcp_sock == 0 path. */
+int field_bug_detected;
+int field_null_seen;
+
+SEC("sockops")
+__naked void sock_ops_get_field_same_reg(void)
+{
+	asm volatile (
+		"r7 = *(u32 *)(r1 + %[is_fullsock_off]);"
+		"r1 = *(u32 *)(r1 + %[snd_cwnd_off]);"
+		"if r7 != 0 goto 2f;"
+		"if r1 == 0 goto 1f;"
+		"r1 = %[field_bug_detected] ll;"
+		"r2 = 1;"
+		"*(u32 *)(r1 + 0) = r2;"
+		"goto 2f;"
+	"1:"
+		"r1 = %[field_null_seen] ll;"
+		"r2 = 1;"
+		"*(u32 *)(r1 + 0) = r2;"
+	"2:"
+		"r0 = 1;"
+		"exit;"
+		:
+		: __imm_const(is_fullsock_off, offsetof(struct bpf_sock_ops, is_fullsock)),
+		  __imm_const(snd_cwnd_off, offsetof(struct bpf_sock_ops, snd_cwnd)),
+		  __imm_addr(field_bug_detected),
+		  __imm_addr(field_null_seen)
+		: __clobber_all);
+}
+
+/* SOCK_OPS_GET_SK: different-register, is_fullsock == 0 path. */
+int diff_reg_bug_detected;
+int diff_reg_null_seen;
+
+SEC("sockops")
+__naked void sock_ops_get_sk_diff_reg(void)
+{
+	asm volatile (
+		"r7 = r1;"
+		"r6 = *(u32 *)(r7 + %[is_fullsock_off]);"
+		"r2 = *(u64 *)(r7 + %[sk_off]);"
+		"if r6 != 0 goto 2f;"
+		"if r2 == 0 goto 1f;"
+		"r1 = %[diff_reg_bug_detected] ll;"
+		"r3 = 1;"
+		"*(u32 *)(r1 + 0) = r3;"
+		"goto 2f;"
+	"1:"
+		"r1 = %[diff_reg_null_seen] ll;"
+		"r3 = 1;"
+		"*(u32 *)(r1 + 0) = r3;"
+	"2:"
+		"r0 = 1;"
+		"exit;"
+		:
+		: __imm_const(is_fullsock_off, offsetof(struct bpf_sock_ops, is_fullsock)),
+		  __imm_const(sk_off, offsetof(struct bpf_sock_ops, sk)),
+		  __imm_addr(diff_reg_bug_detected),
+		  __imm_addr(diff_reg_null_seen)
+		: __clobber_all);
+}
+
+char _license[] SEC("license") = "GPL";