From: Edward Cree <ecree@solarflare.com>
To: <davem@davemloft.net>,
Alexei Starovoitov <alexei.starovoitov@gmail.com>,
Alexei Starovoitov <ast@fb.com>,
Daniel Borkmann <daniel@iogearbox.net>
Cc: <netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
iovisor-dev <iovisor-dev@lists.iovisor.org>
Subject: [PATCH v5 net-next 06/12] selftests/bpf: add a test to test_align
Date: Mon, 7 Aug 2017 15:28:00 +0100 [thread overview]
Message-ID: <a56184eb-cb65-7ca8-8a05-46160ff39c2e@solarflare.com> (raw)
In-Reply-To: <ad840039-8d4a-b2a9-b2eb-a8f079926b53@solarflare.com>
New test adds 14 to the unknown value before adding to the packet pointer,
meaning there's no 'fixed offset' field and instead we add into the
var_off, yielding a '4n+2' value.
Signed-off-by: Edward Cree <ecree@solarflare.com>
---
tools/testing/selftests/bpf/test_align.c | 67 ++++++++++++++++++++++++++++++++
1 file changed, 67 insertions(+)
diff --git a/tools/testing/selftests/bpf/test_align.c b/tools/testing/selftests/bpf/test_align.c
index 62232e4d..74cc4a6 100644
--- a/tools/testing/selftests/bpf/test_align.c
+++ b/tools/testing/selftests/bpf/test_align.c
@@ -374,6 +374,73 @@ static struct bpf_align_test tests[] = {
{33, "R5=pkt(id=4,off=18,r=22,umax_value=2040,var_off=(0x0; 0x7fc))"},
},
},
+ {
+ .descr = "packet variable offset 2",
+ .insns = {
+ /* Create an unknown offset, (4n+2)-aligned */
+ LOAD_UNKNOWN(BPF_REG_6),
+ BPF_ALU64_IMM(BPF_LSH, BPF_REG_6, 2),
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_6, 14),
+ /* Add it to the packet pointer */
+ BPF_MOV64_REG(BPF_REG_5, BPF_REG_2),
+ BPF_ALU64_REG(BPF_ADD, BPF_REG_5, BPF_REG_6),
+ /* Check bounds and perform a read */
+ BPF_MOV64_REG(BPF_REG_4, BPF_REG_5),
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_4, 4),
+ BPF_JMP_REG(BPF_JGE, BPF_REG_3, BPF_REG_4, 1),
+ BPF_EXIT_INSN(),
+ BPF_LDX_MEM(BPF_W, BPF_REG_6, BPF_REG_5, 0),
+ /* Make a (4n) offset from the value we just read */
+ BPF_ALU64_IMM(BPF_AND, BPF_REG_6, 0xff),
+ BPF_ALU64_IMM(BPF_LSH, BPF_REG_6, 2),
+ /* Add it to the packet pointer */
+ BPF_ALU64_REG(BPF_ADD, BPF_REG_5, BPF_REG_6),
+ /* Check bounds and perform a read */
+ BPF_MOV64_REG(BPF_REG_4, BPF_REG_5),
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_4, 4),
+ BPF_JMP_REG(BPF_JGE, BPF_REG_3, BPF_REG_4, 1),
+ BPF_EXIT_INSN(),
+ BPF_LDX_MEM(BPF_W, BPF_REG_6, BPF_REG_5, 0),
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .prog_type = BPF_PROG_TYPE_SCHED_CLS,
+ .matches = {
+ /* Calculated offset in R6 has unknown value, but known
+ * alignment of 4.
+ */
+ {8, "R2=pkt(id=0,off=0,r=8,imm=0)"},
+ {8, "R6=inv(id=0,umax_value=1020,var_off=(0x0; 0x3fc))"},
+ /* Adding 14 makes R6 be (4n+2) */
+ {9, "R6=inv(id=0,umin_value=14,umax_value=1034,var_off=(0x2; 0x7fc))"},
+ /* Packet pointer has (4n+2) offset */
+ {11, "R5=pkt(id=1,off=0,r=0,umin_value=14,umax_value=1034,var_off=(0x2; 0x7fc))"},
+ {13, "R4=pkt(id=1,off=4,r=0,umin_value=14,umax_value=1034,var_off=(0x2; 0x7fc))"},
+ /* At the time the word size load is performed from R5,
+ * its total fixed offset is NET_IP_ALIGN + reg->off (0)
+ * which is 2. Then the variable offset is (4n+2), so
+ * the total offset is 4-byte aligned and meets the
+ * load's requirements.
+ */
+ {15, "R5=pkt(id=1,off=0,r=4,umin_value=14,umax_value=1034,var_off=(0x2; 0x7fc))"},
+ /* Newly read value in R6 was shifted left by 2, so has
+ * known alignment of 4.
+ */
+ {18, "R6=inv(id=0,umax_value=1020,var_off=(0x0; 0x3fc))"},
+ /* Added (4n) to packet pointer's (4n+2) var_off, giving
+ * another (4n+2).
+ */
+ {19, "R5=pkt(id=2,off=0,r=0,umin_value=14,umax_value=2054,var_off=(0x2; 0xffc))"},
+ {21, "R4=pkt(id=2,off=4,r=0,umin_value=14,umax_value=2054,var_off=(0x2; 0xffc))"},
+ /* At the time the word size load is performed from R5,
+ * its total fixed offset is NET_IP_ALIGN + reg->off (0)
+ * which is 2. Then the variable offset is (4n+2), so
+ * the total offset is 4-byte aligned and meets the
+ * load's requirements.
+ */
+ {23, "R5=pkt(id=2,off=0,r=4,umin_value=14,umax_value=2054,var_off=(0x2; 0xffc))"},
+ },
+ },
};
static int probe_filter_length(const struct bpf_insn *fp)
next prev parent reply other threads:[~2017-08-07 14:28 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-07 14:21 [PATCH v5 net-next 00/12] bpf: rewrite value tracking in verifier Edward Cree
2017-08-07 14:26 ` [PATCH v5 net-next 01/12] bpf/verifier: rework value tracking Edward Cree
2017-08-07 14:26 ` [PATCH v5 net-next 02/12] bpf/verifier: track signed and unsigned min/max values Edward Cree
2017-08-07 14:26 ` [PATCH v5 net-next 03/12] bpf/verifier: more concise register state logs for constant var_off Edward Cree
2017-08-07 14:27 ` [PATCH v5 net-next 04/12] selftests/bpf: change test_verifier expectations Edward Cree
2017-08-07 14:27 ` [PATCH v5 net-next 05/12] selftests/bpf: rewrite test_align Edward Cree
2017-08-07 14:28 ` Edward Cree [this message]
2017-08-07 14:28 ` [PATCH v5 net-next 07/12] selftests/bpf: add test for bogus operations on pointers Edward Cree
2017-08-07 14:29 ` [PATCH v5 net-next 08/12] selftests/bpf: don't try to access past MAX_PACKET_OFF in test_verifier Edward Cree
2017-08-07 14:29 ` [PATCH v5 net-next 09/12] selftests/bpf: add tests for subtraction & negative numbers Edward Cree
2017-08-07 14:29 ` [PATCH v5 net-next 10/12] selftests/bpf: variable offset negative tests Edward Cree
2017-08-07 14:30 ` [PATCH v5 net-next 11/12] Documentation: describe the new eBPF verifier value tracking behaviour Edward Cree
2017-08-07 14:30 ` [PATCH v5 net-next 12/12] bpf/verifier: increase complexity limit to 128k Edward Cree
2017-08-08 0:46 ` [PATCH v5 net-next 00/12] bpf: rewrite value tracking in verifier Daniel Borkmann
2017-08-09 0:51 ` David Miller
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