diff options
| author | Andrey Ignatov <rdna@fb.com> | 2019-04-03 23:22:42 -0700 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2019-04-05 16:50:08 +0200 |
| commit | 07f9196241f8bceef975dd15f894f8ed51425d55 (patch) | |
| tree | a4881fdfd7e9487249bf28017d18394560a02fef /tools | |
| parent | 107c26a70ca81bfc33657366ad69d02fdc9efc9d (diff) | |
| download | linux-07f9196241f8bceef975dd15f894f8ed51425d55.tar.bz2 | |
selftests/bpf: Test unbounded var_off stack access
Test the case when reg->smax_value is too small/big and can overflow,
and separately min and max values outside of stack bounds.
Example of output:
# ./test_verifier
#856/p indirect variable-offset stack access, unbounded OK
#857/p indirect variable-offset stack access, max out of bound OK
#858/p indirect variable-offset stack access, min out of bound OK
Signed-off-by: Andrey Ignatov <rdna@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Diffstat (limited to 'tools')
| -rw-r--r-- | tools/testing/selftests/bpf/verifier/var_off.c | 57 |
1 files changed, 55 insertions, 2 deletions
diff --git a/tools/testing/selftests/bpf/verifier/var_off.c b/tools/testing/selftests/bpf/verifier/var_off.c index f5d5ff18ef22..8504ac937809 100644 --- a/tools/testing/selftests/bpf/verifier/var_off.c +++ b/tools/testing/selftests/bpf/verifier/var_off.c @@ -40,7 +40,35 @@ .prog_type = BPF_PROG_TYPE_LWT_IN, }, { - "indirect variable-offset stack access, out of bound", + "indirect variable-offset stack access, unbounded", + .insns = { + BPF_MOV64_IMM(BPF_REG_2, 6), + BPF_MOV64_IMM(BPF_REG_3, 28), + /* Fill the top 16 bytes of the stack. */ + BPF_ST_MEM(BPF_DW, BPF_REG_10, -16, 0), + BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0), + /* Get an unknown value. */ + BPF_LDX_MEM(BPF_DW, BPF_REG_4, BPF_REG_1, offsetof(struct bpf_sock_ops, + bytes_received)), + /* Check the lower bound but don't check the upper one. */ + BPF_JMP_IMM(BPF_JSLT, BPF_REG_4, 0, 4), + /* Point the lower bound to initialized stack. Offset is now in range + * from fp-16 to fp+0x7fffffffffffffef, i.e. max value is unbounded. + */ + BPF_ALU64_IMM(BPF_SUB, BPF_REG_4, 16), + BPF_ALU64_REG(BPF_ADD, BPF_REG_4, BPF_REG_10), + BPF_MOV64_IMM(BPF_REG_5, 8), + /* Dereference it indirectly. */ + BPF_EMIT_CALL(BPF_FUNC_getsockopt), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }, + .errstr = "R4 unbounded indirect variable offset stack access", + .result = REJECT, + .prog_type = BPF_PROG_TYPE_SOCK_OPS, +}, +{ + "indirect variable-offset stack access, max out of bound", .insns = { /* Fill the top 8 bytes of the stack */ BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0), @@ -60,7 +88,32 @@ BPF_EXIT_INSN(), }, .fixup_map_hash_8b = { 5 }, - .errstr = "invalid stack type R2 var_off", + .errstr = "R2 max value is outside of stack bound", + .result = REJECT, + .prog_type = BPF_PROG_TYPE_LWT_IN, +}, +{ + "indirect variable-offset stack access, min out of bound", + .insns = { + /* Fill the top 8 bytes of the stack */ + BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0), + /* Get an unknown value */ + BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, 0), + /* Make it small and 4-byte aligned */ + BPF_ALU64_IMM(BPF_AND, BPF_REG_2, 4), + BPF_ALU64_IMM(BPF_SUB, BPF_REG_2, 516), + /* add it to fp. We now have either fp-516 or fp-512, but + * we don't know which + */ + BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_10), + /* dereference it indirectly */ + BPF_LD_MAP_FD(BPF_REG_1, 0), + BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }, + .fixup_map_hash_8b = { 5 }, + .errstr = "R2 min value is outside of stack bound", .result = REJECT, .prog_type = BPF_PROG_TYPE_LWT_IN, }, |