diff mbox series

[bpf-next,v2,2/3] bpf/selftests: add bpf_get_task_stack retval bounds verifier test

Message ID 20210416204704.2816874-3-davemarchevsky@fb.com (mailing list archive)
State Accepted
Delegated to: BPF
Headers show
Series bpf: refine retval for bpf_get_task_stack helper | expand

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netdev/cc_maintainers warning 7 maintainers not CCed: linux-kselftest@vger.kernel.org netdev@vger.kernel.org kpsingh@kernel.org andrii@kernel.org kafai@fb.com john.fastabend@gmail.com shuah@kernel.org
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Commit Message

Dave Marchevsky April 16, 2021, 8:47 p.m. UTC 
Add a bpf_iter test which feeds bpf_get_task_stack's return value into
seq_write after confirming it's positive. No attempt to bound the value
from above is made.

Load will fail if verifier does not refine retval range based on
buf sz input to bpf_get_task_stack.

Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
---
 .../selftests/bpf/verifier/bpf_get_stack.c    | 43 +++++++++++++++++++
 1 file changed, 43 insertions(+)
diff mbox series

Patch

diff --git a/tools/testing/selftests/bpf/verifier/bpf_get_stack.c b/tools/testing/selftests/bpf/verifier/bpf_get_stack.c
index 69b048cf46d9..3e024c891178 100644
--- a/tools/testing/selftests/bpf/verifier/bpf_get_stack.c
+++ b/tools/testing/selftests/bpf/verifier/bpf_get_stack.c
@@ -42,3 +42,46 @@ 
 	.result = ACCEPT,
 	.prog_type = BPF_PROG_TYPE_TRACEPOINT,
 },
+{
+	"bpf_get_task_stack return R0 range is refined",
+	.insns = {
+	BPF_LDX_MEM(BPF_DW, BPF_REG_6, BPF_REG_1, 0),
+	BPF_LDX_MEM(BPF_DW, BPF_REG_6, BPF_REG_6, 0), // ctx->meta->seq
+	BPF_LDX_MEM(BPF_DW, BPF_REG_7, BPF_REG_1, 8), // ctx->task
+	BPF_LD_MAP_FD(BPF_REG_1, 0), // fixup_map_array_48b
+	BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
+	BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
+	BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
+	BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
+	BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 2),
+	BPF_MOV64_IMM(BPF_REG_0, 0),
+	BPF_EXIT_INSN(),
+	BPF_JMP_IMM(BPF_JNE, BPF_REG_7, 0, 2),
+	BPF_MOV64_IMM(BPF_REG_0, 0),
+	BPF_EXIT_INSN(),
+
+	BPF_MOV64_REG(BPF_REG_1, BPF_REG_7),
+	BPF_MOV64_REG(BPF_REG_2, BPF_REG_0),
+	BPF_MOV64_REG(BPF_REG_9, BPF_REG_0), // keep buf for seq_write
+	BPF_MOV64_IMM(BPF_REG_3, 48),
+	BPF_MOV64_IMM(BPF_REG_4, 0),
+	BPF_EMIT_CALL(BPF_FUNC_get_task_stack),
+	BPF_JMP_IMM(BPF_JSGT, BPF_REG_0, 0, 2),
+	BPF_MOV64_IMM(BPF_REG_0, 0),
+	BPF_EXIT_INSN(),
+
+	BPF_MOV64_REG(BPF_REG_1, BPF_REG_6),
+	BPF_MOV64_REG(BPF_REG_2, BPF_REG_9),
+	BPF_MOV64_REG(BPF_REG_3, BPF_REG_0),
+	BPF_EMIT_CALL(BPF_FUNC_seq_write),
+
+	BPF_MOV64_IMM(BPF_REG_0, 0),
+	BPF_EXIT_INSN(),
+	},
+	.result = ACCEPT,
+	.prog_type = BPF_PROG_TYPE_TRACING,
+	.expected_attach_type = BPF_TRACE_ITER,
+	.kfunc = "task",
+	.runs = -1, // Don't run, just load
+	.fixup_map_array_48b = { 3 },
+},