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authorJiong Wang <jiong.wang@netronome.com>2018-12-15 03:34:40 -0500
committerAlexei Starovoitov <ast@kernel.org>2018-12-18 14:45:01 -0800
commit0bae2d4d62d523f06ff1a8e88ce38b45400acd28 (patch)
treebf6f6180c0843475a553345c96f4e4c00c2272ca /tools
parenta38d1107f937ca95dcf820161ef44ea683d6a0b1 (diff)
downloadtalos-obmc-linux-0bae2d4d62d523f06ff1a8e88ce38b45400acd28.tar.gz
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bpf: correct slot_type marking logic to allow more stack slot sharing
Verifier is supposed to support sharing stack slot allocated to ptr with SCALAR_VALUE for privileged program. However this doesn't happen for some cases. The reason is verifier is not clearing slot_type STACK_SPILL for all bytes, it only clears part of them, while verifier is using: slot_type[0] == STACK_SPILL as a convention to check one slot is ptr type. So, the consequence of partial clearing slot_type is verifier could treat a partially overridden ptr slot, which should now be a SCALAR_VALUE slot, still as ptr slot, and rejects some valid programs. Before this patch, test_xdp_noinline.o under bpf selftests, bpf_lxc.o and bpf_netdev.o under Cilium bpf repo, when built with -mattr=+alu32 are rejected due to this issue. After this patch, they all accepted. There is no processed insn number change before and after this patch on Cilium bpf programs. Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com> Signed-off-by: Jiong Wang <jiong.wang@netronome.com> Reviewed-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'tools')
-rw-r--r--tools/testing/selftests/bpf/test_verifier.c34
1 files changed, 32 insertions, 2 deletions
diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
index f9de7fe0c26d..cf242734e2eb 100644
--- a/tools/testing/selftests/bpf/test_verifier.c
+++ b/tools/testing/selftests/bpf/test_verifier.c
@@ -1001,15 +1001,45 @@ static struct bpf_test tests[] = {
BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_1, -8),
/* mess up with R1 pointer on stack */
BPF_ST_MEM(BPF_B, BPF_REG_10, -7, 0x23),
- /* fill back into R0 should fail */
+ /* fill back into R0 is fine for priv.
+ * R0 now becomes SCALAR_VALUE.
+ */
BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_10, -8),
+ /* Load from R0 should fail. */
+ BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_0, 8),
BPF_EXIT_INSN(),
},
.errstr_unpriv = "attempt to corrupt spilled",
- .errstr = "corrupted spill",
+ .errstr = "R0 invalid mem access 'inv",
.result = REJECT,
},
{
+ "check corrupted spill/fill, LSB",
+ .insns = {
+ BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_1, -8),
+ BPF_ST_MEM(BPF_H, BPF_REG_10, -8, 0xcafe),
+ BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_10, -8),
+ BPF_EXIT_INSN(),
+ },
+ .errstr_unpriv = "attempt to corrupt spilled",
+ .result_unpriv = REJECT,
+ .result = ACCEPT,
+ .retval = POINTER_VALUE,
+ },
+ {
+ "check corrupted spill/fill, MSB",
+ .insns = {
+ BPF_STX_MEM(BPF_DW, BPF_REG_10, BPF_REG_1, -8),
+ BPF_ST_MEM(BPF_W, BPF_REG_10, -4, 0x12345678),
+ BPF_LDX_MEM(BPF_DW, BPF_REG_0, BPF_REG_10, -8),
+ BPF_EXIT_INSN(),
+ },
+ .errstr_unpriv = "attempt to corrupt spilled",
+ .result_unpriv = REJECT,
+ .result = ACCEPT,
+ .retval = POINTER_VALUE,
+ },
+ {
"invalid src register in STX",
.insns = {
BPF_STX_MEM(BPF_B, BPF_REG_10, -1, -1),
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