32417fb376
Currently, system properties are passed via the environment variable ANDROID_PROPERTY_WORKSPACE and a file descriptor passed from parent to child. This is insecure for setuid executables, as the environment variable can be changed by the caller. Modify system property handling so that we get the properties from a root owned properties file, rather than using an environment variable. Fall back to the environment variable if the file doesn't exist. Bug: 8045561 Change-Id: I54f3efa98cf7d63d88788da5ce0d19e34fd7851a
110 lines
3.5 KiB
C
110 lines
3.5 KiB
C
/*
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* Copyright (C) 2008 The Android Open Source Project
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#ifndef _INCLUDE_SYS__SYSTEM_PROPERTIES_H
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#define _INCLUDE_SYS__SYSTEM_PROPERTIES_H
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#ifndef _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_
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#error you should #include <sys/system_properties.h> instead
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#else
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#include <sys/system_properties.h>
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typedef struct prop_area prop_area;
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typedef struct prop_msg prop_msg;
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#define PROP_AREA_MAGIC 0x504f5250
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#define PROP_AREA_VERSION 0x45434f76
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#define PROP_SERVICE_NAME "property_service"
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#define PROP_FILENAME "/dev/__properties__"
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/* #define PROP_MAX_ENTRIES 247 */
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/* 247 -> 32620 bytes (<32768) */
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#define TOC_NAME_LEN(toc) ((toc) >> 24)
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#define TOC_TO_INFO(area, toc) ((prop_info*) (((char*) area) + ((toc) & 0xFFFFFF)))
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struct prop_area {
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unsigned volatile count;
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unsigned volatile serial;
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unsigned magic;
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unsigned version;
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unsigned reserved[4];
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unsigned toc[1];
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};
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#define SERIAL_VALUE_LEN(serial) ((serial) >> 24)
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#define SERIAL_DIRTY(serial) ((serial) & 1)
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struct prop_info {
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char name[PROP_NAME_MAX];
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unsigned volatile serial;
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char value[PROP_VALUE_MAX];
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};
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struct prop_msg
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{
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unsigned cmd;
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char name[PROP_NAME_MAX];
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char value[PROP_VALUE_MAX];
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};
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#define PROP_MSG_SETPROP 1
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/*
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** Rules:
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**
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** - there is only one writer, but many readers
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** - prop_area.count will never decrease in value
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** - once allocated, a prop_info's name will not change
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** - once allocated, a prop_info's offset will not change
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** - reading a value requires the following steps
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** 1. serial = pi->serial
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** 2. if SERIAL_DIRTY(serial), wait*, then goto 1
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** 3. memcpy(local, pi->value, SERIAL_VALUE_LEN(serial) + 1)
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** 4. if pi->serial != serial, goto 2
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**
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** - writing a value requires the following steps
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** 1. pi->serial = pi->serial | 1
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** 2. memcpy(pi->value, local_value, value_len)
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** 3. pi->serial = (value_len << 24) | ((pi->serial + 1) & 0xffffff)
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**
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** Improvements:
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** - maintain the toc sorted by pi->name to allow lookup
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** by binary search
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**
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*/
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#define PROP_PATH_RAMDISK_DEFAULT "/default.prop"
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#define PROP_PATH_SYSTEM_BUILD "/system/build.prop"
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#define PROP_PATH_SYSTEM_DEFAULT "/system/default.prop"
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#define PROP_PATH_LOCAL_OVERRIDE "/data/local.prop"
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#endif
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#endif
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