Fix: bytecode validator: reject specialized load instructions

[lttng-modules.git] / lttng-filter-validator.c

diff --git a/lttng-filter-validator.c b/lttng-filter-validator.c
index c7b81bb6bbd193187434bd5f2b5f21a48f3fff7a..2a5db1198215aabfc1d4e39f77cfc26e0f1b49cf 100644 (file)
--- a/lttng-filter-validator.c
+++ b/lttng-filter-validator.c
@@ -1,27 +1,10 @@
-/*
+/* SPDX-License-Identifier: MIT
+ *
  * lttng-filter-validator.c
  *
  * LTTng modules filter bytecode validator.
  *
  * Copyright (C) 2010-2016 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this software and associated documentation files (the "Software"), to deal
- * in the Software without restriction, including without limitation the rights
- * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- * copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in
- * all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
- * SOFTWARE.
  */
 
 #include <linux/types.h>
@@ -303,6 +286,7 @@ int bytecode_validate_overflow(struct bytecode_runtime *bytecode,
        }
 
        case FILTER_OP_RETURN:
+       case FILTER_OP_RETURN_S64:
        {
                if (unlikely(pc + sizeof(struct return_op)
                                > start_pc + bytecode->len)) {
@@ -513,6 +497,7 @@ int bytecode_validate_overflow(struct bytecode_runtime *bytecode,
                if (unlikely(pc + sizeof(struct load_op) + sizeof(struct get_symbol)
                                > start_pc + bytecode->len)) {
                        ret = -ERANGE;
+                       break;
                }
                ret = validate_get_symbol(bytecode, sym);
                break;
@@ -586,6 +571,7 @@ int validate_instruction_context(struct bytecode_runtime *bytecode,
        }
 
        case FILTER_OP_RETURN:
+       case FILTER_OP_RETURN_S64:
        {
                goto end;
        }
@@ -990,60 +976,30 @@ int validate_instruction_context(struct bytecode_runtime *bytecode,
                dbg_printk("Validate load field\n");
                break;
        }
+
+       /*
+        * Disallow already specialized bytecode op load field instructions to
+        * ensure that the received bytecode does not:
+        *
+        * - Read user-space memory without proper get_user accessors,
+        * - Read a memory area larger than the memory targeted by the instrumentation.
+        */
        case FILTER_OP_LOAD_FIELD_S8:
-       {
-               dbg_printk("Validate load field s8\n");
-               break;
-       }
        case FILTER_OP_LOAD_FIELD_S16:
-       {
-               dbg_printk("Validate load field s16\n");
-               break;
-       }
        case FILTER_OP_LOAD_FIELD_S32:
-       {
-               dbg_printk("Validate load field s32\n");
-               break;
-       }
        case FILTER_OP_LOAD_FIELD_S64:
-       {
-               dbg_printk("Validate load field s64\n");
-               break;
-       }
        case FILTER_OP_LOAD_FIELD_U8:
-       {
-               dbg_printk("Validate load field u8\n");
-               break;
-       }
        case FILTER_OP_LOAD_FIELD_U16:
-       {
-               dbg_printk("Validate load field u16\n");
-               break;
-       }
        case FILTER_OP_LOAD_FIELD_U32:
-       {
-               dbg_printk("Validate load field u32\n");
-               break;
-       }
        case FILTER_OP_LOAD_FIELD_U64:
-       {
-               dbg_printk("Validate load field u64\n");
-               break;
-       }
        case FILTER_OP_LOAD_FIELD_STRING:
-       {
-               dbg_printk("Validate load field string\n");
-               break;
-       }
        case FILTER_OP_LOAD_FIELD_SEQUENCE:
-       {
-               dbg_printk("Validate load field sequence\n");
-               break;
-       }
        case FILTER_OP_LOAD_FIELD_DOUBLE:
        {
-               dbg_printk("Validate load field double\n");
-               break;
+               dbg_printk("Validate load field, reject specialized load instruction (%d)\n",
+                               (int) opcode);
+               ret = -EINVAL;
+               goto end;
        }
 
        case FILTER_OP_GET_SYMBOL:
@@ -1183,6 +1139,28 @@ int exec_insn(struct bytecode_runtime *bytecode,
                goto end;
        }
 
+       case FILTER_OP_RETURN_S64:
+       {
+               if (!vstack_ax(stack)) {
+                       printk(KERN_WARNING "Empty stack\n");
+                       ret = -EINVAL;
+                       goto end;
+               }
+               switch (vstack_ax(stack)->type) {
+               case REG_S64:
+                       break;
+               default:
+               case REG_TYPE_UNKNOWN:
+                       printk(KERN_WARNING "Unexpected register type %d at end of bytecode\n",
+                               (int) vstack_ax(stack)->type);
+                       ret = -EINVAL;
+                       goto end;
+               }
+
+               ret = 0;
+               goto end;
+       }
+
        /* binary */
        case FILTER_OP_MUL:
        case FILTER_OP_DIV: