This is a note to let you know that I've just added the patch titled
selftests/bpf: Add verifier test for PTR_TO_MEM spill
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
selftests-bpf-add-verifier-test-for-ptr_to_mem-spill.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 4237e9f4a96228ccc8a7abe5e4b30834323cd353 Mon Sep 17 00:00:00 2001
From: Gilad Reti <gilad.reti@xxxxxxxxx>
Date: Wed, 13 Jan 2021 07:38:08 +0200
Subject: selftests/bpf: Add verifier test for PTR_TO_MEM spill
From: Gilad Reti <gilad.reti@xxxxxxxxx>
commit 4237e9f4a96228ccc8a7abe5e4b30834323cd353 upstream.
Add a test to check that the verifier is able to recognize spilling of
PTR_TO_MEM registers, by reserving a ringbuf buffer, forcing the spill
of a pointer holding the buffer address to the stack, filling it back
in from the stack and writing to the memory area pointed by it.
The patch was partially contributed by CyberArk Software, Inc.
Signed-off-by: Gilad Reti <gilad.reti@xxxxxxxxx>
Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxx>
Acked-by: Yonghong Song <yhs@xxxxxx>
Acked-by: KP Singh <kpsingh@xxxxxxxxxx>
Link: https://lore.kernel.org/bpf/20210113053810.13518-2-gilad.reti@xxxxxxxxx
Cc: Lorenz Bauer <lmb@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
tools/testing/selftests/bpf/test_verifier.c | 12 ++++++++
tools/testing/selftests/bpf/verifier/spill_fill.c | 30 ++++++++++++++++++++++
2 files changed, 41 insertions(+), 1 deletion(-)
--- a/tools/testing/selftests/bpf/test_verifier.c
+++ b/tools/testing/selftests/bpf/test_verifier.c
@@ -50,7 +50,7 @@
#define MAX_INSNS BPF_MAXINSNS
#define MAX_TEST_INSNS 1000000
#define MAX_FIXUPS 8
-#define MAX_NR_MAPS 20
+#define MAX_NR_MAPS 21
#define MAX_TEST_RUNS 8
#define POINTER_VALUE 0xcafe4all
#define TEST_DATA_LEN 64
@@ -87,6 +87,7 @@ struct bpf_test {
int fixup_sk_storage_map[MAX_FIXUPS];
int fixup_map_event_output[MAX_FIXUPS];
int fixup_map_reuseport_array[MAX_FIXUPS];
+ int fixup_map_ringbuf[MAX_FIXUPS];
const char *errstr;
const char *errstr_unpriv;
uint32_t insn_processed;
@@ -640,6 +641,7 @@ static void do_test_fixup(struct bpf_tes
int *fixup_sk_storage_map = test->fixup_sk_storage_map;
int *fixup_map_event_output = test->fixup_map_event_output;
int *fixup_map_reuseport_array = test->fixup_map_reuseport_array;
+ int *fixup_map_ringbuf = test->fixup_map_ringbuf;
if (test->fill_helper) {
test->fill_insns = calloc(MAX_TEST_INSNS, sizeof(struct bpf_insn));
@@ -817,6 +819,14 @@ static void do_test_fixup(struct bpf_tes
fixup_map_reuseport_array++;
} while (*fixup_map_reuseport_array);
}
+ if (*fixup_map_ringbuf) {
+ map_fds[20] = create_map(BPF_MAP_TYPE_RINGBUF, 0,
+ 0, 4096);
+ do {
+ prog[*fixup_map_ringbuf].imm = map_fds[20];
+ fixup_map_ringbuf++;
+ } while (*fixup_map_ringbuf);
+ }
}
struct libcap {
--- a/tools/testing/selftests/bpf/verifier/spill_fill.c
+++ b/tools/testing/selftests/bpf/verifier/spill_fill.c
@@ -29,6 +29,36 @@
.result_unpriv = ACCEPT,
},
{
+ "check valid spill/fill, ptr to mem",
+ .insns = {
+ /* reserve 8 byte ringbuf memory */
+ BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
+ BPF_LD_MAP_FD(BPF_REG_1, 0),
+ BPF_MOV64_IMM(BPF_REG_2, 8),
+ BPF_MOV64_IMM(BPF_REG_3, 0),
+ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_ringbuf_reserve),
+ /* store a pointer to the reserved memory in R6 */
+ BPF_MOV64_REG(BPF_REG_6, BPF_REG_0),
+ /* check whether the reservation was successful */
+ BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 6),
+ /* spill R6(mem) into the stack */
+ BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_6, -8),
+ /* fill it back in R7 */
+ BPF_LDX_MEM(BPF_DW, BPF_REG_7, BPF_REG_10, -8),
+ /* should be able to access *(R7) = 0 */
+ BPF_ST_MEM(BPF_DW, BPF_REG_7, 0, 0),
+ /* submit the reserved ringbuf memory */
+ BPF_MOV64_REG(BPF_REG_1, BPF_REG_7),
+ BPF_MOV64_IMM(BPF_REG_2, 0),
+ BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_ringbuf_submit),
+ BPF_MOV64_IMM(BPF_REG_0, 0),
+ BPF_EXIT_INSN(),
+ },
+ .fixup_map_ringbuf = { 1 },
+ .result = ACCEPT,
+ .result_unpriv = ACCEPT,
+},
+{
"check corrupted spill/fill",
.insns = {
/* spill R1(ctx) into stack */
Patches currently in stable-queue which might be from gilad.reti@xxxxxxxxx are
queue-5.10/selftests-bpf-add-verifier-test-for-ptr_to_mem-spill.patch
