selftests: bpf: verifier: add tests for JSET interpretation

Validate that the verifier reasons correctly about the bounds
and removes dead code based on results of JSET instruction.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools/testing/selftests/bpf/test_verifier.c

@@ -14265,6 +14265,102 @@ static struct bpf_test tests[] = {
 		.retval = 2,
 		.data = { 1, 0, 0, 0, 0, 0, 0, 1, },
 	},
+	{
+		"jset: known const compare",
+		.insns = {
+			BPF_MOV64_IMM(BPF_REG_0, 1),
+			BPF_JMP_IMM(BPF_JSET, BPF_REG_0, 1, 1),
+			BPF_LDX_MEM(BPF_B, BPF_REG_8, BPF_REG_9, 0),
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SOCKET_FILTER,
+		.retval_unpriv = 1,
+		.result_unpriv = ACCEPT,
+		.retval = 1,
+		.result = ACCEPT,
+	},
+	{
+		"jset: known const compare bad",
+		.insns = {
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			BPF_JMP_IMM(BPF_JSET, BPF_REG_0, 1, 1),
+			BPF_LDX_MEM(BPF_B, BPF_REG_8, BPF_REG_9, 0),
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SOCKET_FILTER,
+		.errstr_unpriv = "!read_ok",
+		.result_unpriv = REJECT,
+		.errstr = "!read_ok",
+		.result = REJECT,
+	},
+	{
+		"jset: unknown const compare taken",
+		.insns = {
+			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
+				     BPF_FUNC_get_prandom_u32),
+			BPF_JMP_IMM(BPF_JSET, BPF_REG_0, 1, 1),
+			BPF_JMP_IMM(BPF_JA, 0, 0, 1),
+			BPF_LDX_MEM(BPF_B, BPF_REG_8, BPF_REG_9, 0),
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SOCKET_FILTER,
+		.errstr_unpriv = "!read_ok",
+		.result_unpriv = REJECT,
+		.errstr = "!read_ok",
+		.result = REJECT,
+	},
+	{
+		"jset: unknown const compare not taken",
+		.insns = {
+			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
+				     BPF_FUNC_get_prandom_u32),
+			BPF_JMP_IMM(BPF_JSET, BPF_REG_0, 1, 1),
+			BPF_LDX_MEM(BPF_B, BPF_REG_8, BPF_REG_9, 0),
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SOCKET_FILTER,
+		.errstr_unpriv = "!read_ok",
+		.result_unpriv = REJECT,
+		.errstr = "!read_ok",
+		.result = REJECT,
+	},
+	{
+		"jset: half-known const compare",
+		.insns = {
+			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
+				     BPF_FUNC_get_prandom_u32),
+			BPF_ALU64_IMM(BPF_OR, BPF_REG_0, 2),
+			BPF_JMP_IMM(BPF_JSET, BPF_REG_0, 3, 1),
+			BPF_LDX_MEM(BPF_B, BPF_REG_8, BPF_REG_9, 0),
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SOCKET_FILTER,
+		.result_unpriv = ACCEPT,
+		.result = ACCEPT,
+	},
+	{
+		"jset: range",
+		.insns = {
+			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
+				     BPF_FUNC_get_prandom_u32),
+			BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+			BPF_MOV64_IMM(BPF_REG_0, 0),
+			BPF_ALU64_IMM(BPF_AND, BPF_REG_1, 0xff),
+			BPF_JMP_IMM(BPF_JSET, BPF_REG_1, 0xf0, 3),
+			BPF_JMP_IMM(BPF_JLT, BPF_REG_1, 0x10, 1),
+			BPF_LDX_MEM(BPF_B, BPF_REG_8, BPF_REG_9, 0),
+			BPF_EXIT_INSN(),
+			BPF_JMP_IMM(BPF_JSET, BPF_REG_1, 0x10, 1),
+			BPF_EXIT_INSN(),
+			BPF_JMP_IMM(BPF_JGE, BPF_REG_1, 0x10, 1),
+			BPF_LDX_MEM(BPF_B, BPF_REG_8, BPF_REG_9, 0),
+			BPF_EXIT_INSN(),
+		},
+		.prog_type = BPF_PROG_TYPE_SOCKET_FILTER,
+		.result_unpriv = ACCEPT,
+		.result = ACCEPT,
+	},
 };
 
 static int probe_filter_length(const struct bpf_insn *fp)