[PATCH V2 net-next 6/6] test_bpf: add tests checking that JIT/interpreter sets A and X to 0.

Nicolas Schichan
2015-08-04T13:20:59Z

It is mandatory for the JIT or interpreter to reset the A and X
registers to 0 before running the filter. Check that it is the case on
various ALU and JMP instructions.

Signed-off-by: Nicolas Schichan <nschichan@freebox.fr>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>

---
lib/test_bpf.c | 158 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 158 insertions(+)

diff --git a/lib/test_bpf.c b/lib/test_bpf.c
index e6ef56d..d137739 100644
--- a/lib/test_bpf.c
+++ b/lib/test_bpf.c
@@ -4931,6 +4931,164 @@ static struct bpf_test tests[] = {
},
{ {0x40, 0x88ee99ff } },
},
+ /*
+ * verify that the interpreter or JIT correctly sets A and X
+ * to 0.
+ */
+ {
+ "ADD default X",
+ .u.insns = {
+ /*
+ * A = 0x42
+ * A = A + X
+ * ret A
+ */
+ BPF_STMT(BPF_LD | BPF_IMM, 0x42),
+ BPF_STMT(BPF_ALU | BPF_ADD | BPF_X, 0),
+ BPF_STMT(BPF_RET | BPF_A, 0x0),
+ },
+ CLASSIC | FLAG_NO_DATA,
+ {},
+ { {0x1, 0x42 } },
+ },
+ {
+ "ADD default A",
+ .u.insns = {
+ /*
+ * A = A + 0x42
+ * ret A
+ */
+ BPF_STMT(BPF_ALU | BPF_ADD | BPF_K, 0x42),
+ BPF_STMT(BPF_RET | BPF_A, 0x0),
+ },
+ CLASSIC | FLAG_NO_DATA,
+ {},
+ { {0x1, 0x42 } },
+ },
+ {
+ "SUB default X",
+ .u.insns = {
+ /*
+ * A = 0x66
+ * A = A - X
+ * ret A
+ */
+ BPF_STMT(BPF_LD | BPF_IMM, 0x66),
+ BPF_STMT(BPF_ALU | BPF_SUB | BPF_X, 0),
+ BPF_STMT(BPF_RET | BPF_A, 0x0),
+ },
+ CLASSIC | FLAG_NO_DATA,
+ {},
+ { {0x1, 0x66 } },
+ },
+ {
+ "SUB default A",
+ .u.insns = {
+ /*
+ * A = A - -0x66
+ * ret A
+ */
+ BPF_STMT(BPF_ALU | BPF_SUB | BPF_K, -0x66),
+ BPF_STMT(BPF_RET | BPF_A, 0x0),
+ },
+ CLASSIC | FLAG_NO_DATA,
+ {},
+ { {0x1, 0x66 } },
+ },
+ {
+ "MUL default X",
+ .u.insns = {
+ /*
+ * A = 0x42
+ * A = A * X
+ * ret A
+ */
+ BPF_STMT(BPF_LD | BPF_IMM, 0x42),
+ BPF_STMT(BPF_ALU | BPF_MUL | BPF_X, 0),
+ BPF_STMT(BPF_RET | BPF_A, 0x0),
+ },
+ CLASSIC | FLAG_NO_DATA,
+ {},
+ { {0x1, 0x0 } },
+ },
+ {
+ "MUL default A",
+ .u.insns = {
+ /*
+ * A = A * 0x66
+ * ret A
+ */
+ BPF_STMT(BPF_ALU | BPF_MUL | BPF_K, 0x66),
+ BPF_STMT(BPF_RET | BPF_A, 0x0),
+ },
+ CLASSIC | FLAG_NO_DATA,
+ {},
+ { {0x1, 0x0 } },
+ },
+ {
+ "DIV default X",
+ .u.insns = {
+ /*
+ * A = 0x42
+ * A = A / X ; this halt the filter execution if X is 0
+ * ret 0x42
+ */
+ BPF_STMT(BPF_LD | BPF_IMM, 0x42),
+ BPF_STMT(BPF_ALU | BPF_DIV | BPF_X, 0),
+ BPF_STMT(BPF_RET | BPF_K, 0x42),
+ },
+ CLASSIC | FLAG_NO_DATA,
+ {},
+ { {0x1, 0x0 } },
+ },
+ {
+ "DIV default A",
+ .u.insns = {
+ /*
+ * A = A / 1
+ * ret A
+ */
+ BPF_STMT(BPF_ALU | BPF_DIV | BPF_K, 0x1),
+ BPF_STMT(BPF_RET | BPF_A, 0x0),
+ },
+ CLASSIC | FLAG_NO_DATA,
+ {},
+ { {0x1, 0x0 } },
+ },
+ {
+ "JMP EQ default A",
+ .u.insns = {
+ /*
+ * cmp A, 0x0, 0, 1
+ * ret 0x42
+ * ret 0x66
+ */
+ BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, 0x0, 0, 1),
+ BPF_STMT(BPF_RET | BPF_K, 0x42),
+ BPF_STMT(BPF_RET | BPF_K, 0x66),
+ },
+ CLASSIC | FLAG_NO_DATA,
+ {},
+ { {0x1, 0x42 } },
+ },
+ {
+ "JMP EQ default X",
+ .u.insns = {
+ /*
+ * A = 0x0
+ * cmp A, X, 0, 1
+ * ret 0x42
+ * ret 0x66
+ */
+ BPF_STMT(BPF_LD | BPF_IMM, 0x0),
+ BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_X, 0x0, 0, 1),
+ BPF_STMT(BPF_RET | BPF_K, 0x42),
+ BPF_STMT(BPF_RET | BPF_K, 0x66),
+ },
+ CLASSIC | FLAG_NO_DATA,
+ {},
+ { {0x1, 0x42 } },
+ },
};

static struct net_device dev;
--
1.9.1