diff options
-rw-r--r-- | include/linux/bpf_verifier.h | 1 | ||||
-rw-r--r-- | kernel/bpf/verifier.c | 61 | ||||
-rw-r--r-- | tools/testing/selftests/bpf/test_verifier.c | 120 |
3 files changed, 169 insertions, 13 deletions
diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index 27b74947cd2b..573cca00a0e6 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -172,6 +172,7 @@ struct bpf_verifier_state_list { #define BPF_ALU_SANITIZE_SRC 1U #define BPF_ALU_SANITIZE_DST 2U #define BPF_ALU_NEG_VALUE (1U << 2) +#define BPF_ALU_NON_POINTER (1U << 3) #define BPF_ALU_SANITIZE (BPF_ALU_SANITIZE_SRC | \ BPF_ALU_SANITIZE_DST) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index f6bc62a9ee8e..56674a7c3778 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -3103,6 +3103,40 @@ static int retrieve_ptr_limit(const struct bpf_reg_state *ptr_reg, } } +static bool can_skip_alu_sanitation(const struct bpf_verifier_env *env, + const struct bpf_insn *insn) +{ + return env->allow_ptr_leaks || BPF_SRC(insn->code) == BPF_K; +} + +static int update_alu_sanitation_state(struct bpf_insn_aux_data *aux, + u32 alu_state, u32 alu_limit) +{ + /* If we arrived here from different branches with different + * state or limits to sanitize, then this won't work. + */ + if (aux->alu_state && + (aux->alu_state != alu_state || + aux->alu_limit != alu_limit)) + return -EACCES; + + /* Corresponding fixup done in fixup_bpf_calls(). */ + aux->alu_state = alu_state; + aux->alu_limit = alu_limit; + return 0; +} + +static int sanitize_val_alu(struct bpf_verifier_env *env, + struct bpf_insn *insn) +{ + struct bpf_insn_aux_data *aux = cur_aux(env); + + if (can_skip_alu_sanitation(env, insn)) + return 0; + + return update_alu_sanitation_state(aux, BPF_ALU_NON_POINTER, 0); +} + static int sanitize_ptr_alu(struct bpf_verifier_env *env, struct bpf_insn *insn, const struct bpf_reg_state *ptr_reg, @@ -3117,7 +3151,7 @@ static int sanitize_ptr_alu(struct bpf_verifier_env *env, struct bpf_reg_state tmp; bool ret; - if (env->allow_ptr_leaks || BPF_SRC(insn->code) == BPF_K) + if (can_skip_alu_sanitation(env, insn)) return 0; /* We already marked aux for masking from non-speculative @@ -3133,19 +3167,8 @@ static int sanitize_ptr_alu(struct bpf_verifier_env *env, if (retrieve_ptr_limit(ptr_reg, &alu_limit, opcode, off_is_neg)) return 0; - - /* If we arrived here from different branches with different - * limits to sanitize, then this won't work. - */ - if (aux->alu_state && - (aux->alu_state != alu_state || - aux->alu_limit != alu_limit)) + if (update_alu_sanitation_state(aux, alu_state, alu_limit)) return -EACCES; - - /* Corresponding fixup done in fixup_bpf_calls(). */ - aux->alu_state = alu_state; - aux->alu_limit = alu_limit; - do_sim: /* Simulate and find potential out-of-bounds access under * speculative execution from truncation as a result of @@ -3418,6 +3441,8 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env, s64 smin_val, smax_val; u64 umin_val, umax_val; u64 insn_bitness = (BPF_CLASS(insn->code) == BPF_ALU64) ? 64 : 32; + u32 dst = insn->dst_reg; + int ret; if (insn_bitness == 32) { /* Relevant for 32-bit RSH: Information can propagate towards @@ -3452,6 +3477,11 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env, switch (opcode) { case BPF_ADD: + ret = sanitize_val_alu(env, insn); + if (ret < 0) { + verbose(env, "R%d tried to add from different pointers or scalars\n", dst); + return ret; + } if (signed_add_overflows(dst_reg->smin_value, smin_val) || signed_add_overflows(dst_reg->smax_value, smax_val)) { dst_reg->smin_value = S64_MIN; @@ -3471,6 +3501,11 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env, dst_reg->var_off = tnum_add(dst_reg->var_off, src_reg.var_off); break; case BPF_SUB: + ret = sanitize_val_alu(env, insn); + if (ret < 0) { + verbose(env, "R%d tried to sub from different pointers or scalars\n", dst); + return ret; + } if (signed_sub_overflows(dst_reg->smin_value, smax_val) || signed_sub_overflows(dst_reg->smax_value, smin_val)) { /* Overflow possible, we know nothing */ diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c index 10d44446e801..2fd90d456892 100644 --- a/tools/testing/selftests/bpf/test_verifier.c +++ b/tools/testing/selftests/bpf/test_verifier.c @@ -6934,6 +6934,126 @@ static struct bpf_test tests[] = { .retval = 1, }, { + "map access: mixing value pointer and scalar, 1", + .insns = { + // load map value pointer into r0 and r2 + BPF_MOV64_IMM(BPF_REG_0, 1), + BPF_LD_MAP_FD(BPF_REG_ARG1, 0), + BPF_MOV64_REG(BPF_REG_ARG2, BPF_REG_FP), + BPF_ALU64_IMM(BPF_ADD, BPF_REG_ARG2, -16), + BPF_ST_MEM(BPF_DW, BPF_REG_FP, -16, 0), + BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem), + BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 1), + BPF_EXIT_INSN(), + // load some number from the map into r1 + BPF_LDX_MEM(BPF_B, BPF_REG_1, BPF_REG_0, 0), + // depending on r1, branch: + BPF_JMP_IMM(BPF_JNE, BPF_REG_1, 0, 3), + // branch A + BPF_MOV64_REG(BPF_REG_2, BPF_REG_0), + BPF_MOV64_IMM(BPF_REG_3, 0), + BPF_JMP_A(2), + // branch B + BPF_MOV64_IMM(BPF_REG_2, 0), + BPF_MOV64_IMM(BPF_REG_3, 0x100000), + // common instruction + BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_3), + // depending on r1, branch: + BPF_JMP_IMM(BPF_JNE, BPF_REG_1, 0, 1), + // branch A + BPF_JMP_A(4), + // branch B + BPF_MOV64_IMM(BPF_REG_0, 0x13371337), + // verifier follows fall-through + BPF_JMP_IMM(BPF_JNE, BPF_REG_2, 0x100000, 2), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + // fake-dead code; targeted from branch A to + // prevent dead code sanitization + BPF_LDX_MEM(BPF_B, BPF_REG_0, BPF_REG_0, 0), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }, + .fixup_map_array_48b = { 1 }, + .result = ACCEPT, + .result_unpriv = REJECT, + .errstr_unpriv = "R2 tried to add from different pointers or scalars", + .retval = 0, + }, + { + "map access: mixing value pointer and scalar, 2", + .insns = { + // load map value pointer into r0 and r2 + BPF_MOV64_IMM(BPF_REG_0, 1), + BPF_LD_MAP_FD(BPF_REG_ARG1, 0), + BPF_MOV64_REG(BPF_REG_ARG2, BPF_REG_FP), + BPF_ALU64_IMM(BPF_ADD, BPF_REG_ARG2, -16), + BPF_ST_MEM(BPF_DW, BPF_REG_FP, -16, 0), + BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem), + BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 1), + BPF_EXIT_INSN(), + // load some number from the map into r1 + BPF_LDX_MEM(BPF_B, BPF_REG_1, BPF_REG_0, 0), + // depending on r1, branch: + BPF_JMP_IMM(BPF_JEQ, BPF_REG_1, 0, 3), + // branch A + BPF_MOV64_IMM(BPF_REG_2, 0), + BPF_MOV64_IMM(BPF_REG_3, 0x100000), + BPF_JMP_A(2), + // branch B + BPF_MOV64_REG(BPF_REG_2, BPF_REG_0), + BPF_MOV64_IMM(BPF_REG_3, 0), + // common instruction + BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_3), + // depending on r1, branch: + BPF_JMP_IMM(BPF_JNE, BPF_REG_1, 0, 1), + // branch A + BPF_JMP_A(4), + // branch B + BPF_MOV64_IMM(BPF_REG_0, 0x13371337), + // verifier follows fall-through + BPF_JMP_IMM(BPF_JNE, BPF_REG_2, 0x100000, 2), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + // fake-dead code; targeted from branch A to + // prevent dead code sanitization + BPF_LDX_MEM(BPF_B, BPF_REG_0, BPF_REG_0, 0), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }, + .fixup_map_array_48b = { 1 }, + .result = ACCEPT, + .result_unpriv = REJECT, + .errstr_unpriv = "R2 tried to add from different maps or paths", + .retval = 0, + }, + { + "sanitation: alu with different scalars", + .insns = { + BPF_MOV64_IMM(BPF_REG_0, 1), + BPF_LD_MAP_FD(BPF_REG_ARG1, 0), + BPF_MOV64_REG(BPF_REG_ARG2, BPF_REG_FP), + BPF_ALU64_IMM(BPF_ADD, BPF_REG_ARG2, -16), + BPF_ST_MEM(BPF_DW, BPF_REG_FP, -16, 0), + BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem), + BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, 1), + BPF_EXIT_INSN(), + BPF_LDX_MEM(BPF_B, BPF_REG_1, BPF_REG_0, 0), + BPF_JMP_IMM(BPF_JEQ, BPF_REG_1, 0, 3), + BPF_MOV64_IMM(BPF_REG_2, 0), + BPF_MOV64_IMM(BPF_REG_3, 0x100000), + BPF_JMP_A(2), + BPF_MOV64_IMM(BPF_REG_2, 42), + BPF_MOV64_IMM(BPF_REG_3, 0x100001), + BPF_ALU64_REG(BPF_ADD, BPF_REG_2, BPF_REG_3), + BPF_MOV64_REG(BPF_REG_0, BPF_REG_2), + BPF_EXIT_INSN(), + }, + .fixup_map_array_48b = { 1 }, + .result = ACCEPT, + .retval = 0x100000, + }, + { "map access: value_ptr += known scalar, upper oob arith, test 1", .insns = { BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0), |