Commit efd6286f authored by Eduard Zingerman's avatar Eduard Zingerman Committed by Alexei Starovoitov
Browse files

selftests/bpf: test case for relaxed prunning of active_lock.id 



Check that verifier.c:states_equal() uses check_ids() to match
consistent active_lock/map_value configurations. This allows to prune
states with active spin locks even if numerical values of
active_lock ids do not match across compared states.

Signed-off-by: default avatarEduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20221209135733.28851-8-eddyz87@gmail.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 2026f206

tools/testing/selftests/bpf/verifier/spin_lock.c

+75 −0
Original line number Diff line number Diff line
@@ -370,3 +370,78 @@ 
	.prog_type = BPF_PROG_TYPE_SCHED_CLS,

	.flags = BPF_F_TEST_STATE_FREQ,

},

/* Make sure that regsafe() compares ids for spin lock records using

 * check_ids():

 *  1: r9 = map_lookup_elem(...)  ; r9.id == 1

 *  2: r8 = map_lookup_elem(...)  ; r8.id == 2

 *  3: r7 = ktime_get_ns()

 *  4: r6 = ktime_get_ns()

 *  5: if r6 > r7 goto <9>

 *  6: spin_lock(r8)

 *  7: r9 = r8

 *  8: goto <10>

 *  9: spin_lock(r9)

 * 10: spin_unlock(r9)             ; r9.id == 1 || r9.id == 2 and lock is active,

 *                                 ; second visit to (10) should be considered safe

 *                                 ; if check_ids() is used.

 * 11: exit(0)

 */

{

	"spin_lock: regsafe() check_ids() similar id mappings",

	.insns = {

	BPF_ST_MEM(BPF_W, BPF_REG_10, -4, 0),

	/* r9 = map_lookup_elem(...) */

	BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),

	BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4),

	BPF_LD_MAP_FD(BPF_REG_1,

		      0),

	BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem),

	BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 24),

	BPF_MOV64_REG(BPF_REG_9, BPF_REG_0),

	/* r8 = map_lookup_elem(...) */

	BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),

	BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4),

	BPF_LD_MAP_FD(BPF_REG_1,

		      0),

	BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem),

	BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 18),

	BPF_MOV64_REG(BPF_REG_8, BPF_REG_0),

	/* r7 = ktime_get_ns() */

	BPF_EMIT_CALL(BPF_FUNC_ktime_get_ns),

	BPF_MOV64_REG(BPF_REG_7, BPF_REG_0),

	/* r6 = ktime_get_ns() */

	BPF_EMIT_CALL(BPF_FUNC_ktime_get_ns),

	BPF_MOV64_REG(BPF_REG_6, BPF_REG_0),

	/* if r6 > r7 goto +5      ; no new information about the state is derived from

	 *                         ; this check, thus produced verifier states differ

	 *                         ; only in 'insn_idx'

	 * spin_lock(r8)

	 * r9 = r8

	 * goto unlock

	 */

	BPF_JMP_REG(BPF_JGT, BPF_REG_6, BPF_REG_7, 5),

	BPF_MOV64_REG(BPF_REG_1, BPF_REG_8),

	BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, 4),

	BPF_EMIT_CALL(BPF_FUNC_spin_lock),

	BPF_MOV64_REG(BPF_REG_9, BPF_REG_8),

	BPF_JMP_A(3),

	/* spin_lock(r9) */

	BPF_MOV64_REG(BPF_REG_1, BPF_REG_9),

	BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, 4),

	BPF_EMIT_CALL(BPF_FUNC_spin_lock),

	/* spin_unlock(r9) */

	BPF_MOV64_REG(BPF_REG_1, BPF_REG_9),

	BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, 4),

	BPF_EMIT_CALL(BPF_FUNC_spin_unlock),

	/* exit(0) */

	BPF_MOV64_IMM(BPF_REG_0, 0),

	BPF_EXIT_INSN(),

	},

	.fixup_map_spin_lock = { 3, 10 },

	.result = VERBOSE_ACCEPT,

	.errstr = "28: safe",

	.result_unpriv = REJECT,

	.errstr_unpriv = "",

	.prog_type = BPF_PROG_TYPE_CGROUP_SKB,

	.flags = BPF_F_TEST_STATE_FREQ,

},