Android vendor.img中文件执行权问题

问题

Android 9、11往vendor.img增加文件，烧写到设备后发现增加的可执行文件没有执行权限。经过漫长查找，终于找到了问题的根源，谨以此篇献给哪些脚踏实地的人们。

根本原因

system/core/libcutils/fs_config.cpp文件，fs_config函数根据android_dirs、android_files中的配置修改文件的uid、gui、mode(权限)。除了/vendor/bin/、/vendor/xbin/目录下的文件的有执行权限，/vendor目录下的其他文件都没有执行权限。

vendor.img是如何生成的

build/core/Makefile

INSTALLED_VENDORIMAGE_TARGET 

3314 # We just build this directly to the install location.
3315 INSTALLED_VENDORIMAGE_TARGET := $(BUILT_VENDORIMAGE_TARGET)
3316 $(INSTALLED_VENDORIMAGE_TARGET): \
3317     $(INTERNAL_USERIMAGES_DEPS) \
3318     $(INTERNAL_VENDORIMAGE_FILES) \
3319     $(INSTALLED_FILES_FILE_VENDOR) \
3320     $(RECOVERY_FROM_BOOT_PATCH)
3321     $(build-vendorimage-target)

build-vendorimage-target

BUILT_VENDORIMAGE_TARGET

3294 vendorimage_intermediates := \
3295     $(call intermediates-dir-for,PACKAGING,vendor)
3296 BUILT_VENDORIMAGE_TARGET := $(PRODUCT_OUT)/vendor.img
3297 define build-vendorimage-target
3298   # $(hide) /usr/bin/python build/tools/rcmerge.py $(subst full_,,$(TARGET_PRODUCT)) vnd
3299   $(call pretty,"Target vendor fs image: $(INSTALLED_VENDORIMAGE_TARGET)")
3300   @mkdir -p $(TARGET_OUT_VENDOR)
3301   @rm -rf $(TARGET_OUT_VENDOR)/avm
3302   @mkdir -p $(TARGET_OUT_VENDOR)/avm
3303   $(call create-vendor-odm-symlink)
3304   @mkdir -p $(vendorimage_intermediates) && rm -rf $(vendorimage_intermediates)/vendor_image_info.txt
3305   $(hide) cp -rf $(TOP)/vendor/autochips/proprietary/frameworks/base/avm/file/* $(TARGET_OUT_VENDOR)/avm
3306   $(call generate-image-prop-dictionary, $(vendorimage_intermediates)/vendor_image_info.txt,vendor,skip_fsck=true)
3307   PATH=$(INTERNAL_USERIMAGES_BINARY_PATHS):$$PATH \
3308       $(BUILD_IMAGE) \
3309           $(TARGET_OUT_VENDOR) $(vendorimage_intermediates)/vendor_image_info.txt \
3310           $(INSTALLED_VENDORIMAGE_TARGET) $(TARGET_OUT)
3311   $(call assert-max-image-size,$(INSTALLED_VENDORIMAGE_TARGET) $(RECOVERY_FROM_BOOT_PATCH),$(BOARD_VENDORIMAGE_PARTITION_SIZE))
3312 endef

build_image

build/core/config.mk

635 BUILD_IMAGE := $(HOST_OUT_EXECUTABLES)/build_image$(HOST_EXECUTABLE_SUFFIX)

out/host/linux-x86/bin/build_image

Builds output_image from the given input_directory, properties_file,
and writes the image to target_output_directory.Usage:  build_image input_directory properties_file output_image \target_output_directory

build_image.py

build/tools/releasetools/build_image.py

BuildImageMkfs

231 def BuildImageMkfs(in_dir, prop_dict, out_file, target_out, fs_config):
232   """Builds a pure image for the files under in_dir and writes it to out_file.
233
234   Args:
235     in_dir: Path to input directory.
236     prop_dict: A property dict that contains info like partition size. Values
237         will be updated with computed values.
238     out_file: The output image file.
239     target_out: Path to the TARGET_OUT directory as in Makefile. It actually
240         points to the /system directory under PRODUCT_OUT. fs_config (the one
241         under system/core/libcutils) reads device specific FS config files from
242         there.
243     fs_config: The fs_config file that drives the prototype
244
245   Raises:
246     BuildImageError: On build image failures.
247   """

 build_command

mkuserimg_mke2fs -s out/target/product/ac8257_64bit/vendor out/target/product/ac8257_64bit/vendor.img ext4 vendor 825540608 -j 0 -D out/target/product/ac8257_64bit/system -L vendor -M 0 --inode_size 256  out/target/product/ac8257_64bit/obj/ETC/file_contexts.bin_intermediates/file_contexts.bin

mkuserimg_mke2fs.py

system/extras/ext4_utils/mkuserimg_mke2fs.py

mke2fs

Usage: mke2fs [-c|-l filename] [-b block-size] [-C cluster-size][-i bytes-per-inode] [-I inode-size] [-J journal-options][-G flex-group-size] [-N number-of-inodes] [-d root-directory][-m reserved-blocks-percentage] [-o creator-os][-g blocks-per-group] [-L volume-label] [-M last-mounted-directory][-O feature[,...]] [-r fs-revision] [-E extended-option[,...]][-t fs-type] [-T usage-type ] [-U UUID] [-e errors_behavior][-z undo_file][-jnqvDFSV] device [blocks-count]

MKE2FS_CONFIG=out/soong/.temp/tmpGyRCz5mke2fs -O ^has_journal -L vendor -I 256  -M /vendor -m 0 -E android_sparse -t ext4 -b 4096 out/target/product/ac8257_64bit/vendor.img 201548

e2fsdroid

e2fsdroid -p out/target/product/ac8257_64bit/system -S out/target/product/ac8257_64bit/obj/ETC/file_contexts.bin_intermediates/file_contexts.bin -f out/target/product/ac8257_64bit/vendor -a /vendor out/target/product/ac8257_64bit/vendor.img

file_contexts

obj/ETC/file_contexts.bin_intermediates

system/sepolicy/private/file_contexts
device/autochips/sepolicy/basic/plat_private/file_contexts
device/autochips/sepolicy/bsp/plat_private/file_contexts

SetUpInDirAndFsConfig

e2fsdroid源在何处

external/e2fsprogs/contrib/android/e2fsdroid.c 

Usage

e2fsdroid [-B block_list] [-D basefs_out] [-T timestamp][-C fs_config] [-S file_contexts] [-p product_out][-a mountpoint] [-d basefs_in] [-f src_dir] [-e] [-s] image

android_configure_fs

326 errcode_t android_configure_fs(ext2_filsys fs, char *src_dir, char *target_out,
327                    char *mountpoint,
328                    struct selinux_opt *seopts EXT2FS_ATTR((unused)),
329                    unsigned int nopt EXT2FS_ATTR((unused)),
330                    char *fs_config_file, time_t fixed_time,
331                    const struct ugid_map* uid_map,
332                    const struct ugid_map* gid_map)
333 {359     /* Load the FS config */
360     if (fs_config_file) {
361         retval = load_canned_fs_config(fs_config_file);
362         if (retval < 0) {
363             com_err(__func__, retval,
364                 _("while loading fs_config \"%s\""),
365                 fs_config_file);
366             return retval;
367         }
368         fs_config_func = canned_fs_config;
369     } else if (mountpoint)
370         fs_config_func = fs_config;
371
372     return __android_configure_fs(fs, src_dir, target_out, mountpoint,
373                       fs_config_func, sehnd, fixed_time,
374                       uid_map, gid_map);
375 }

fs_config

system/core/libcutils/fs_config.cpp文件，fs_config函数根据android_dirs、android_files中的配置修改文件的uid、gui、mode(权限)。除了/vendor/bin/、/vendor/xbin/目录下的文件的有执行权限，/vendor目录下的其他文件都没有执行权限。

366     for (pc = dir ? android_dirs : android_files; pc->prefix; pc++) {
367         if (fs_config_cmp(dir, pc->prefix, strlen(pc->prefix), path, plen)) {
368             break;
369         }
370     }
371     *uid = pc->uid;
372     *gid = pc->gid;
373     *mode = (*mode & (~07777)) | pc->mode;
374     *capabilities = pc->capabilities;
375 }

 android_dirs

 59 static const struct fs_path_config android_dirs[] = {60         // clang-format off61     { 00770, AID_SYSTEM,       AID_CACHE,        0, "cache" },62     { 00555, AID_ROOT,         AID_ROOT,         0, "config" },63     { 00771, AID_SYSTEM,       AID_SYSTEM,       0, "data/app" },64     { 00771, AID_SYSTEM,       AID_SYSTEM,       0, "data/app-private" },65     { 00771, AID_SYSTEM,       AID_SYSTEM,       0, "data/app-ephemeral" },66     { 00771, AID_ROOT,         AID_ROOT,         0, "data/dalvik-cache" },67     { 00771, AID_SYSTEM,       AID_SYSTEM,       0, "data/data" },68     { 00771, AID_SHELL,        AID_SHELL,        0, "data/local/tmp" },69     { 00771, AID_SHELL,        AID_SHELL,        0, "data/local" },70     { 00770, AID_DHCP,         AID_DHCP,         0, "data/misc/dhcp" },71     { 00771, AID_SHARED_RELRO, AID_SHARED_RELRO, 0, "data/misc/shared_relro" },72     { 01771, AID_SYSTEM,       AID_MISC,         0, "data/misc" },73     { 00775, AID_MEDIA_RW,     AID_MEDIA_RW,     0, "data/media/Music" },74     { 00775, AID_MEDIA_RW,     AID_MEDIA_RW,     0, "data/media" },75     { 00750, AID_ROOT,         AID_SHELL,        0, "data/nativetest" },76     { 00750, AID_ROOT,         AID_SHELL,        0, "data/nativetest64" },77     { 00750, AID_ROOT,         AID_SHELL,        0, "data/benchmarktest" },78     { 00750, AID_ROOT,         AID_SHELL,        0, "data/benchmarktest64" },79     { 00775, AID_ROOT,         AID_ROOT,         0, "data/preloads" },80     { 00771, AID_SYSTEM,       AID_SYSTEM,       0, "data" },81     { 00755, AID_ROOT,         AID_SYSTEM,       0, "mnt" },82     { 00751, AID_ROOT,         AID_SHELL,        0, "product/bin" },83     { 00777, AID_ROOT,         AID_ROOT,         0, "sdcard" },84     { 00751, AID_ROOT,         AID_SDCARD_R,     0, "storage" },85     { 00751, AID_ROOT,         AID_SHELL,        0, "system/bin" },86     { 00755, AID_ROOT,         AID_ROOT,         0, "system/etc/ppp" },87     { 00755, AID_ROOT,         AID_SHELL,        0, "system/vendor" },88     { 00751, AID_ROOT,         AID_SHELL,        0, "system/xbin" },89     { 00751, AID_ROOT,         AID_SHELL,        0, "system/apex/*/bin" },90     { 00751, AID_ROOT,         AID_SHELL,        0, "system_ext/bin" },91     { 00751, AID_ROOT,         AID_SHELL,        0, "system_ext/apex/*/bin" },92     { 00751, AID_ROOT,         AID_SHELL,        0, "vendor/bin" },93     { 00755, AID_ROOT,         AID_SHELL,        0, "vendor" },94     { 00755, AID_ROOT,         AID_ROOT,         0, 0 },95         // clang-format on96 };

android_files

139 static const struct fs_path_config android_files[] = {
140         // clang-format off
141     { 00644, AID_SYSTEM,    AID_SYSTEM,    0, "data/app/*" },
142     { 00644, AID_SYSTEM,    AID_SYSTEM,    0, "data/app-ephemeral/*" },
143     { 00644, AID_SYSTEM,    AID_SYSTEM,    0, "data/app-private/*" },
144     { 00644, AID_APP,       AID_APP,       0, "data/data/*" },
145     { 00644, AID_MEDIA_RW,  AID_MEDIA_RW,  0, "data/media/*" },
146     { 00640, AID_ROOT,      AID_SHELL,     0, "data/nativetest/tests.txt" },
147     { 00640, AID_ROOT,      AID_SHELL,     0, "data/nativetest64/tests.txt" },
148     { 00750, AID_ROOT,      AID_SHELL,     0, "data/nativetest/*" },
149     { 00750, AID_ROOT,      AID_SHELL,     0, "data/nativetest64/*" },
150     { 00750, AID_ROOT,      AID_SHELL,     0, "data/benchmarktest/*" },
151     { 00750, AID_ROOT,      AID_SHELL,     0, "data/benchmarktest64/*" },
152     { 00600, AID_ROOT,      AID_ROOT,      0, "default.prop" }, // legacy
153     { 00600, AID_ROOT,      AID_ROOT,      0, "system/etc/prop.default" },
154     { 00600, AID_ROOT,      AID_ROOT,      0, "odm/build.prop" }, // legacy; only for P release
155     { 00600, AID_ROOT,      AID_ROOT,      0, "odm/default.prop" }, // legacy; only for P release
156     { 00600, AID_ROOT,      AID_ROOT,      0, "odm/etc/build.prop" },
157     { 00444, AID_ROOT,      AID_ROOT,      0, odm_conf_dir + 1 },
158     { 00444, AID_ROOT,      AID_ROOT,      0, odm_conf_file + 1 },
159     { 00444, AID_ROOT,      AID_ROOT,      0, oem_conf_dir + 1 },
160     { 00444, AID_ROOT,      AID_ROOT,      0, oem_conf_file + 1 },
161     { 00600, AID_ROOT,      AID_ROOT,      0, "product/build.prop" },
162     { 00444, AID_ROOT,      AID_ROOT,      0, product_conf_dir + 1 },
163     { 00444, AID_ROOT,      AID_ROOT,      0, product_conf_file + 1 },
164     { 00600, AID_ROOT,      AID_ROOT,      0, "system_ext/build.prop" },
165     { 00444, AID_ROOT,      AID_ROOT,      0, system_ext_conf_dir + 1 },
166     { 00444, AID_ROOT,      AID_ROOT,      0, system_ext_conf_file + 1 },
167     { 00755, AID_ROOT,      AID_SHELL,     0, "system/bin/crash_dump32" },
168     { 00755, AID_ROOT,      AID_SHELL,     0, "system/bin/crash_dump64" },
169     { 00755, AID_ROOT,      AID_SHELL,     0, "system/bin/debuggerd" },
170     { 00550, AID_LOGD,      AID_LOGD,      0, "system/bin/logd" },
171     { 00700, AID_ROOT,      AID_ROOT,      0, "system/bin/secilc" },
172     { 00750, AID_ROOT,      AID_ROOT,      0, "system/bin/uncrypt" },
173     { 00600, AID_ROOT,      AID_ROOT,      0, "system/build.prop" },
174     { 00444, AID_ROOT,      AID_ROOT,      0, sys_conf_dir + 1 },
175     { 00444, AID_ROOT,      AID_ROOT,      0, sys_conf_file + 1 },
176     { 00440, AID_ROOT,      AID_SHELL,     0, "system/etc/init.goldfish.rc" },
177     { 00550, AID_ROOT,      AID_SHELL,     0, "system/etc/init.goldfish.sh" },
178     { 00550, AID_ROOT,      AID_SHELL,     0, "system/etc/init.ril" },
179     { 00555, AID_ROOT,      AID_ROOT,      0, "system/etc/ppp/*" },
180     { 00555, AID_ROOT,      AID_ROOT,      0, "system/etc/rc.*" },
181     { 00750, AID_ROOT,      AID_ROOT,      0, "vendor/bin/install-recovery.sh" },
182     { 00600, AID_ROOT,      AID_ROOT,      0, "vendor/build.prop" },
183     { 00600, AID_ROOT,      AID_ROOT,      0, "vendor/default.prop" },
184     { 00440, AID_ROOT,      AID_ROOT,      0, "vendor/etc/recovery.img" },
185     { 00444, AID_ROOT,      AID_ROOT,      0, ven_conf_dir + 1 },
186     { 00444, AID_ROOT,      AID_ROOT,      0, ven_conf_file + 1 },
187
188     // the following two files are INTENTIONALLY set-uid, but they
189     // are NOT included on user builds.
190     { 06755, AID_ROOT,      AID_ROOT,      0, "system/xbin/procmem" },
191     { 04750, AID_ROOT,      AID_SHELL,     0, "system/xbin/su" },
192
193     // the following files have enhanced capabilities and ARE included
194     // in user builds.
195     { 00700, AID_SYSTEM,    AID_SHELL,     CAP_MASK_LONG(CAP_BLOCK_SUSPEND),
196                                               "system/bin/inputflinger" },
197     { 00750, AID_ROOT,      AID_SHELL,     CAP_MASK_LONG(CAP_SETUID) |
198                                            CAP_MASK_LONG(CAP_SETGID),
199                                               "system/bin/run-as" },
200     { 00750, AID_ROOT,      AID_SHELL,     CAP_MASK_LONG(CAP_SETUID) |
201                                            CAP_MASK_LONG(CAP_SETGID),
202                                               "system/bin/simpleperf_app_runner" },
203     { 00755, AID_ROOT,      AID_ROOT,      0, "first_stage_ramdisk/system/bin/e2fsck" },
204     { 00755, AID_ROOT,      AID_ROOT,      0, "first_stage_ramdisk/system/bin/tune2fs" },
205     { 00755, AID_ROOT,      AID_ROOT,      0, "first_stage_ramdisk/system/bin/resize2fs" },
206     // generic defaults
207     { 00755, AID_ROOT,      AID_ROOT,      0, "bin/*" },
208     { 00640, AID_ROOT,      AID_SHELL,     0, "fstab.*" },
209     { 00750, AID_ROOT,      AID_SHELL,     0, "init*" },
210     { 00755, AID_ROOT,      AID_SHELL,     0, "odm/bin/*" },
211     { 00755, AID_ROOT,      AID_SHELL,     0, "product/bin/*" },
212     { 00755, AID_ROOT,      AID_SHELL,     0, "system/bin/*" },
213     { 00755, AID_ROOT,      AID_SHELL,     0, "system/xbin/*" },
214     { 00755, AID_ROOT,      AID_SHELL,     0, "system/apex/*/bin/*" },
215     { 00755, AID_ROOT,      AID_SHELL,     0, "system_ext/bin/*" },
216     { 00755, AID_ROOT,      AID_SHELL,     0, "system_ext/apex/*/bin/*" },
217     { 00755, AID_ROOT,      AID_SHELL,     0, "vendor/bin/*" },
218     { 00755, AID_ROOT,      AID_SHELL,     0, "vendor/xbin/*" },
219     { 00771, AID_ROOT,      AID_SYSTEM,    0, "avm/*" },
220     { 00644, AID_ROOT,      AID_ROOT,      0, 0 },
221         // clang-format on
222 };

如何调试

build_image.py

build/core

--- a/tools/releasetools/build_image.py
+++ b/tools/releasetools/build_image.py
@@ -341,8 +341,12 @@ def BuildImageMkfs(in_dir, prop_dict, out_file, target_out, fs_config):raise BuildImageError("Error: unknown filesystem type: {}".format(fs_type))+  if "vendor" == prop_dict["mount_point"]:
+    print("build_command: %s" % (build_command))try:mkfs_output = common.RunAndCheckOutput(build_command)
+    if "vendor" == prop_dict["mount_point"]:
+      print("mkfs_output: %s" % mkfs_output)except:try:du = GetDiskUsage(in_dir)

mkuserimg_mke2fs.py

system/extras

--- a/ext4_utils/mkuserimg_mke2fs.py
+++ b/ext4_utils/mkuserimg_mke2fs.py
@@ -223,6 +223,7 @@ def main(argv):if args.timestamp:mke2fs_env["E2FSPROGS_FAKE_TIME"] = args.timestamp+    print("mke2fs_cmd: %s, mke2fs_env: %s\n" % (mke2fs_cmd, mke2fs_env))output, ret = RunCommand(mke2fs_cmd, mke2fs_env)print(output)if ret != 0:
@@ -234,6 +235,7 @@ def main(argv):if args.timestamp:e2fsdroid_env["E2FSPROGS_FAKE_TIME"] = args.timestamp+  print("e2fsdroid_cmd: %s, e2fsdroid_env: %s\n" % (e2fsdroid_cmd, e2fsdroid_env))output, ret = RunCommand(e2fsdroid_cmd, e2fsdroid_env)# The build script is parsing the raw output of e2fsdroid; keep the pattern# unchanged for now.

 fs_config.cpp

system/core

--- a/libcutils/fs_config.cpp
+++ b/libcutils/fs_config.cpp
@@ -367,6 +367,7 @@ void fs_config(const char* path, int dir, const char* target_out_path, unsigned*break;}}
+    printf("%s %s, prefix: %s %o\n", path, target_out_path, pc->prefix, pc->mode);*uid = pc->uid;*gid = pc->gid;*mode = (*mode & (~07777)) | pc->mode;