Switch run-as to libpackagelistparser.
We already have to have a Java and a native implementation; we don't
need _two_ native implementations.
Change-Id: I0201205ce5079ef9c747abc37b0c8122cf8fb136
diff --git a/run-as/Android.mk b/run-as/Android.mk
index 3774acc..2e305d7 100644
--- a/run-as/Android.mk
+++ b/run-as/Android.mk
@@ -1,12 +1,8 @@
LOCAL_PATH:= $(call my-dir)
+
include $(CLEAR_VARS)
-
-LOCAL_SRC_FILES := run-as.c package.c
-
-LOCAL_SHARED_LIBRARIES := libselinux
-
-LOCAL_MODULE := run-as
-
LOCAL_CFLAGS := -Werror
-
+LOCAL_MODULE := run-as
+LOCAL_SHARED_LIBRARIES := libselinux libpackagelistparser
+LOCAL_SRC_FILES := run-as.cpp
include $(BUILD_EXECUTABLE)
diff --git a/run-as/package.c b/run-as/package.c
deleted file mode 100644
index aea89e5..0000000
--- a/run-as/package.c
+++ /dev/null
@@ -1,556 +0,0 @@
-/*
-**
-** Copyright 2010, The Android Open Source Project
-**
-** Licensed under the Apache License, Version 2.0 (the "License");
-** you may not use this file except in compliance with the License.
-** You may obtain a copy of the License at
-**
-** http://www.apache.org/licenses/LICENSE-2.0
-**
-** Unless required by applicable law or agreed to in writing, software
-** distributed under the License is distributed on an "AS IS" BASIS,
-** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-** See the License for the specific language governing permissions and
-** limitations under the License.
-*/
-#include <errno.h>
-#include <fcntl.h>
-#include <stdio.h>
-#include <string.h>
-#include <sys/mman.h>
-#include <sys/stat.h>
-#include <unistd.h>
-
-#include <private/android_filesystem_config.h>
-#include "package.h"
-
-/*
- * WARNING WARNING WARNING WARNING
- *
- * The following code runs as root on production devices, before
- * the run-as command has dropped the uid/gid. Hence be very
- * conservative and keep in mind the following:
- *
- * - Performance does not matter here, clarity and safety of the code
- * does however. Documentation is a must.
- *
- * - Avoid calling C library functions with complex implementations
- * like malloc() and printf(). You want to depend on simple system
- * calls instead, which behaviour is not going to be altered in
- * unpredictible ways by environment variables or system properties.
- *
- * - Do not trust user input and/or the filesystem whenever possible.
- *
- */
-
-/* The file containing the list of installed packages on the system */
-#define PACKAGES_LIST_FILE "/data/system/packages.list"
-
-/* Copy 'srclen' string bytes from 'src' into buffer 'dst' of size 'dstlen'
- * This function always zero-terminate the destination buffer unless
- * 'dstlen' is 0, even in case of overflow.
- * Returns a pointer into the src string, leaving off where the copy
- * has stopped. The copy will stop when dstlen, srclen or a null
- * character on src has been reached.
- */
-static const char*
-string_copy(char* dst, size_t dstlen, const char* src, size_t srclen)
-{
- const char* srcend = src + srclen;
- const char* dstend = dst + dstlen;
-
- if (dstlen == 0)
- return src;
-
- dstend--; /* make room for terminating zero */
-
- while (dst < dstend && src < srcend && *src != '\0')
- *dst++ = *src++;
-
- *dst = '\0'; /* zero-terminate result */
- return src;
-}
-
-/* Open 'filename' and map it into our address-space.
- * Returns buffer address, or NULL on error
- * On exit, *filesize will be set to the file's size, or 0 on error
- */
-static void*
-map_file(const char* filename, size_t* filesize)
-{
- int fd, ret, old_errno;
- struct stat st;
- size_t length = 0;
- void* address = NULL;
- gid_t oldegid;
-
- *filesize = 0;
-
- /*
- * Temporarily switch effective GID to allow us to read
- * the packages file
- */
-
- oldegid = getegid();
- if (setegid(AID_PACKAGE_INFO) < 0) {
- return NULL;
- }
-
- /* open the file for reading */
- fd = TEMP_FAILURE_RETRY(open(filename, O_RDONLY));
- if (fd < 0) {
- return NULL;
- }
-
- /* restore back to our old egid */
- if (setegid(oldegid) < 0) {
- goto EXIT;
- }
-
- /* get its size */
- ret = TEMP_FAILURE_RETRY(fstat(fd, &st));
- if (ret < 0)
- goto EXIT;
-
- /* Ensure that the file is owned by the system user */
- if ((st.st_uid != AID_SYSTEM) || (st.st_gid != AID_PACKAGE_INFO)) {
- goto EXIT;
- }
-
- /* Ensure that the file has sane permissions */
- if ((st.st_mode & S_IWOTH) != 0) {
- goto EXIT;
- }
-
- /* Ensure that the size is not ridiculously large */
- length = (size_t)st.st_size;
- if ((off_t)length != st.st_size) {
- errno = ENOMEM;
- goto EXIT;
- }
-
- /* Memory-map the file now */
- do {
- address = mmap(NULL, length, PROT_READ, MAP_PRIVATE, fd, 0);
- } while (address == MAP_FAILED && errno == EINTR);
- if (address == MAP_FAILED) {
- address = NULL;
- goto EXIT;
- }
-
- /* We're good, return size */
- *filesize = length;
-
-EXIT:
- /* close the file, preserve old errno for better diagnostics */
- old_errno = errno;
- close(fd);
- errno = old_errno;
-
- return address;
-}
-
-/* unmap the file, but preserve errno */
-static void
-unmap_file(void* address, size_t size)
-{
- int old_errno = errno;
- TEMP_FAILURE_RETRY(munmap(address, size));
- errno = old_errno;
-}
-
-/* Check that a given directory:
- * - exists
- * - is owned by a given uid/gid
- * - is a real directory, not a symlink
- * - isn't readable or writable by others
- *
- * Return 0 on success, or -1 on error.
- * errno is set to EINVAL in case of failed check.
- */
-static int
-check_directory_ownership(const char* path, uid_t uid)
-{
- int ret;
- struct stat st;
-
- do {
- ret = lstat(path, &st);
- } while (ret < 0 && errno == EINTR);
-
- if (ret < 0)
- return -1;
-
- /* must be a real directory, not a symlink */
- if (!S_ISDIR(st.st_mode))
- goto BAD;
-
- /* must be owned by specific uid/gid */
- if (st.st_uid != uid || st.st_gid != uid)
- goto BAD;
-
- /* must not be readable or writable by others */
- if ((st.st_mode & (S_IROTH|S_IWOTH)) != 0)
- goto BAD;
-
- /* everything ok */
- return 0;
-
-BAD:
- errno = EINVAL;
- return -1;
-}
-
-/* This function is used to check the data directory path for safety.
- * We check that every sub-directory is owned by the 'system' user
- * and exists and is not a symlink. We also check that the full directory
- * path is properly owned by the user ID.
- *
- * Return 0 on success, -1 on error.
- */
-int
-check_data_path(const char* dataPath, uid_t uid)
-{
- int nn;
-
- /* the path should be absolute */
- if (dataPath[0] != '/') {
- errno = EINVAL;
- return -1;
- }
-
- /* look for all sub-paths, we do that by finding
- * directory separators in the input path and
- * checking each sub-path independently
- */
- for (nn = 1; dataPath[nn] != '\0'; nn++)
- {
- char subpath[PATH_MAX];
-
- /* skip non-separator characters */
- if (dataPath[nn] != '/')
- continue;
-
- /* handle trailing separator case */
- if (dataPath[nn+1] == '\0') {
- break;
- }
-
- /* found a separator, check that dataPath is not too long. */
- if (nn >= (int)(sizeof subpath)) {
- errno = EINVAL;
- return -1;
- }
-
- /* reject any '..' subpath */
- if (nn >= 3 &&
- dataPath[nn-3] == '/' &&
- dataPath[nn-2] == '.' &&
- dataPath[nn-1] == '.') {
- errno = EINVAL;
- return -1;
- }
-
- /* copy to 'subpath', then check ownership */
- memcpy(subpath, dataPath, nn);
- subpath[nn] = '\0';
-
- if (check_directory_ownership(subpath, AID_SYSTEM) < 0)
- return -1;
- }
-
- /* All sub-paths were checked, now verify that the full data
- * directory is owned by the application uid
- */
- if (check_directory_ownership(dataPath, uid) < 0)
- return -1;
-
- /* all clear */
- return 0;
-}
-
-/* Return TRUE iff a character is a space or tab */
-static inline int
-is_space(char c)
-{
- return (c == ' ' || c == '\t');
-}
-
-/* Skip any space or tab character from 'p' until 'end' is reached.
- * Return new position.
- */
-static const char*
-skip_spaces(const char* p, const char* end)
-{
- while (p < end && is_space(*p))
- p++;
-
- return p;
-}
-
-/* Skip any non-space and non-tab character from 'p' until 'end'.
- * Return new position.
- */
-static const char*
-skip_non_spaces(const char* p, const char* end)
-{
- while (p < end && !is_space(*p))
- p++;
-
- return p;
-}
-
-/* Find the first occurence of 'ch' between 'p' and 'end'
- * Return its position, or 'end' if none is found.
- */
-static const char*
-find_first(const char* p, const char* end, char ch)
-{
- while (p < end && *p != ch)
- p++;
-
- return p;
-}
-
-/* Check that the non-space string starting at 'p' and eventually
- * ending at 'end' equals 'name'. Return new position (after name)
- * on success, or NULL on failure.
- *
- * This function fails is 'name' is NULL, empty or contains any space.
- */
-static const char*
-compare_name(const char* p, const char* end, const char* name)
-{
- /* 'name' must not be NULL or empty */
- if (name == NULL || name[0] == '\0' || p == end)
- return NULL;
-
- /* compare characters to those in 'name', excluding spaces */
- while (*name) {
- /* note, we don't check for *p == '\0' since
- * it will be caught in the next conditional.
- */
- if (p >= end || is_space(*p))
- goto BAD;
-
- if (*p != *name)
- goto BAD;
-
- p++;
- name++;
- }
-
- /* must be followed by end of line or space */
- if (p < end && !is_space(*p))
- goto BAD;
-
- return p;
-
-BAD:
- return NULL;
-}
-
-/* Parse one or more whitespace characters starting from '*pp'
- * until 'end' is reached. Updates '*pp' on exit.
- *
- * Return 0 on success, -1 on failure.
- */
-static int
-parse_spaces(const char** pp, const char* end)
-{
- const char* p = *pp;
-
- if (p >= end || !is_space(*p)) {
- errno = EINVAL;
- return -1;
- }
- p = skip_spaces(p, end);
- *pp = p;
- return 0;
-}
-
-/* Parse a positive decimal number starting from '*pp' until 'end'
- * is reached. Adjust '*pp' on exit. Return decimal value or -1
- * in case of error.
- *
- * If the value is larger than INT_MAX, -1 will be returned,
- * and errno set to EOVERFLOW.
- *
- * If '*pp' does not start with a decimal digit, -1 is returned
- * and errno set to EINVAL.
- */
-static int
-parse_positive_decimal(const char** pp, const char* end)
-{
- const char* p = *pp;
- int value = 0;
- int overflow = 0;
-
- if (p >= end || *p < '0' || *p > '9') {
- errno = EINVAL;
- return -1;
- }
-
- while (p < end) {
- int ch = *p;
- unsigned d = (unsigned)(ch - '0');
- int val2;
-
- if (d >= 10U) /* d is unsigned, no lower bound check */
- break;
-
- val2 = value*10 + (int)d;
- if (val2 < value)
- overflow = 1;
- value = val2;
- p++;
- }
- *pp = p;
-
- if (overflow) {
- errno = EOVERFLOW;
- value = -1;
- }
- return value;
-}
-
-/* Read the system's package database and extract information about
- * 'pkgname'. Return 0 in case of success, or -1 in case of error.
- *
- * If the package is unknown, return -1 and set errno to ENOENT
- * If the package database is corrupted, return -1 and set errno to EINVAL
- */
-int
-get_package_info(const char* pkgName, uid_t userId, PackageInfo *info)
-{
- char* buffer;
- size_t buffer_len;
- const char* p;
- const char* buffer_end;
- int result = -1;
-
- info->uid = 0;
- info->isDebuggable = 0;
- info->dataDir[0] = '\0';
- info->seinfo[0] = '\0';
-
- buffer = map_file(PACKAGES_LIST_FILE, &buffer_len);
- if (buffer == NULL)
- return -1;
-
- p = buffer;
- buffer_end = buffer + buffer_len;
-
- /* expect the following format on each line of the control file:
- *
- * <pkgName> <uid> <debugFlag> <dataDir> <seinfo>
- *
- * where:
- * <pkgName> is the package's name
- * <uid> is the application-specific user Id (decimal)
- * <debugFlag> is 1 if the package is debuggable, or 0 otherwise
- * <dataDir> is the path to the package's data directory (e.g. /data/data/com.example.foo)
- * <seinfo> is the seinfo label associated with the package
- *
- * The file is generated in com.android.server.PackageManagerService.Settings.writeLP()
- */
-
- while (p < buffer_end) {
- /* find end of current line and start of next one */
- const char* end = find_first(p, buffer_end, '\n');
- const char* next = (end < buffer_end) ? end + 1 : buffer_end;
- const char* q;
- int uid, debugFlag;
-
- /* first field is the package name */
- p = compare_name(p, end, pkgName);
- if (p == NULL)
- goto NEXT_LINE;
-
- /* skip spaces */
- if (parse_spaces(&p, end) < 0)
- goto BAD_FORMAT;
-
- /* second field is the pid */
- uid = parse_positive_decimal(&p, end);
- if (uid < 0)
- return -1;
-
- info->uid = (uid_t) uid;
-
- /* skip spaces */
- if (parse_spaces(&p, end) < 0)
- goto BAD_FORMAT;
-
- /* third field is debug flag (0 or 1) */
- debugFlag = parse_positive_decimal(&p, end);
- switch (debugFlag) {
- case 0:
- info->isDebuggable = 0;
- break;
- case 1:
- info->isDebuggable = 1;
- break;
- default:
- goto BAD_FORMAT;
- }
-
- /* skip spaces */
- if (parse_spaces(&p, end) < 0)
- goto BAD_FORMAT;
-
- /* fourth field is data directory path and must not contain
- * spaces.
- */
- q = skip_non_spaces(p, end);
- if (q == p)
- goto BAD_FORMAT;
-
- /* If userId == 0 (i.e. user is device owner) we can use dataDir value
- * from packages.list, otherwise compose data directory as
- * /data/user/$uid/$packageId
- */
- if (userId == 0) {
- p = string_copy(info->dataDir, sizeof info->dataDir, p, q - p);
- } else {
- snprintf(info->dataDir,
- sizeof info->dataDir,
- "/data/user/%d/%s",
- userId,
- pkgName);
- p = q;
- }
-
- /* skip spaces */
- if (parse_spaces(&p, end) < 0)
- goto BAD_FORMAT;
-
- /* fifth field is the seinfo string */
- q = skip_non_spaces(p, end);
- if (q == p)
- goto BAD_FORMAT;
-
- string_copy(info->seinfo, sizeof info->seinfo, p, q - p);
-
- /* Ignore the rest */
- result = 0;
- goto EXIT;
-
- NEXT_LINE:
- p = next;
- }
-
- /* the package is unknown */
- errno = ENOENT;
- result = -1;
- goto EXIT;
-
-BAD_FORMAT:
- errno = EINVAL;
- result = -1;
-
-EXIT:
- unmap_file(buffer, buffer_len);
- return result;
-}
diff --git a/run-as/package.h b/run-as/package.h
deleted file mode 100644
index eeb5913..0000000
--- a/run-as/package.h
+++ /dev/null
@@ -1,44 +0,0 @@
-/*
-**
-** Copyright 2010, The Android Open Source Project
-**
-** Licensed under the Apache License, Version 2.0 (the "License");
-** you may not use this file except in compliance with the License.
-** You may obtain a copy of the License at
-**
-** http://www.apache.org/licenses/LICENSE-2.0
-**
-** Unless required by applicable law or agreed to in writing, software
-** distributed under the License is distributed on an "AS IS" BASIS,
-** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-** See the License for the specific language governing permissions and
-** limitations under the License.
-*/
-#ifndef RUN_AS_PACKAGE_H
-#define RUN_AS_PACKAGE_H
-
-#include <limits.h>
-#include <sys/types.h>
-
-typedef enum {
- PACKAGE_IS_DEBUGGABLE = 0,
- PACKAGE_IS_NOT_DEBUGGABLE,
- PACKAGE_IS_UNKNOWN,
-} PackageStatus;
-
-typedef struct {
- uid_t uid;
- char isDebuggable;
- char dataDir[PATH_MAX];
- char seinfo[PATH_MAX];
-} PackageInfo;
-
-/* see documentation in package.c for these functions */
-
-extern int get_package_info(const char* packageName,
- uid_t userId,
- PackageInfo* info);
-
-extern int check_data_path(const char* dataDir, uid_t uid);
-
-#endif /* RUN_AS_PACKAGE_H */
diff --git a/run-as/run-as.c b/run-as/run-as.c
deleted file mode 100644
index f0fd2fe..0000000
--- a/run-as/run-as.c
+++ /dev/null
@@ -1,224 +0,0 @@
-/*
-**
-** Copyright 2010, The Android Open Source Project
-**
-** Licensed under the Apache License, Version 2.0 (the "License");
-** you may not use this file except in compliance with the License.
-** You may obtain a copy of the License at
-**
-** http://www.apache.org/licenses/LICENSE-2.0
-**
-** Unless required by applicable law or agreed to in writing, software
-** distributed under the License is distributed on an "AS IS" BASIS,
-** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-** See the License for the specific language governing permissions and
-** limitations under the License.
-*/
-
-#define PROGNAME "run-as"
-#define LOG_TAG PROGNAME
-
-#include <dirent.h>
-#include <errno.h>
-#include <paths.h>
-#include <pwd.h>
-#include <stdarg.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <sys/capability.h>
-#include <sys/cdefs.h>
-#include <sys/stat.h>
-#include <sys/types.h>
-#include <time.h>
-#include <unistd.h>
-
-#include <private/android_filesystem_config.h>
-#include <selinux/android.h>
-
-#include "package.h"
-
-/*
- * WARNING WARNING WARNING WARNING
- *
- * This program runs with CAP_SETUID and CAP_SETGID capabilities on Android
- * production devices. Be very conservative when modifying it to avoid any
- * serious security issue. Keep in mind the following:
- *
- * - This program should only run for the 'root' or 'shell' users
- *
- * - Avoid anything that is more complex than simple system calls
- * until the uid/gid has been dropped to that of a normal user
- * or you are sure to exit.
- *
- * This avoids depending on environment variables, system properties
- * and other external factors that may affect the C library in
- * unpredictable ways.
- *
- * - Do not trust user input and/or the filesystem whenever possible.
- *
- * Read README.TXT for more details.
- *
- *
- *
- * The purpose of this program is to run a command as a specific
- * application user-id. Typical usage is:
- *
- * run-as <package-name> <command> <args>
- *
- * The 'run-as' binary is installed with CAP_SETUID and CAP_SETGID file
- * capabilities, but will check the following:
- *
- * - that it is invoked from the 'shell' or 'root' user (abort otherwise)
- * - that '<package-name>' is the name of an installed and debuggable package
- * - that the package's data directory is well-formed (see package.c)
- *
- * If so, it will drop to the application's user id / group id, cd to the
- * package's data directory, then run the command there.
- *
- * NOTE: In the future it might not be possible to cd to the package's data
- * directory under that package's user id / group id, in which case this
- * utility will need to be changed accordingly.
- *
- * This can be useful for a number of different things on production devices:
- *
- * - Allow application developers to look at their own applicative data
- * during development.
- *
- * - Run the 'gdbserver' binary executable to allow native debugging
- */
-
-__noreturn static void
-panic(const char* format, ...)
-{
- va_list args;
- int e = errno;
-
- fprintf(stderr, "%s: ", PROGNAME);
- va_start(args, format);
- vfprintf(stderr, format, args);
- va_end(args);
- exit(e ? -e : 1);
-}
-
-static void
-usage(void)
-{
- panic("Usage:\n " PROGNAME " <package-name> [--user <uid>] <command> [<args>]\n");
-}
-
-int main(int argc, char **argv)
-{
- const char* pkgname;
- uid_t myuid, uid, gid, userAppId = 0;
- int commandArgvOfs = 2, userId = 0;
- PackageInfo info;
- struct __user_cap_header_struct capheader;
- struct __user_cap_data_struct capdata[2];
-
- /* check arguments */
- if (argc < 2) {
- usage();
- }
-
- /* check userid of caller - must be 'shell' or 'root' */
- myuid = getuid();
- if (myuid != AID_SHELL && myuid != AID_ROOT) {
- panic("only 'shell' or 'root' users can run this program\n");
- }
-
- memset(&capheader, 0, sizeof(capheader));
- memset(&capdata, 0, sizeof(capdata));
- capheader.version = _LINUX_CAPABILITY_VERSION_3;
- capdata[CAP_TO_INDEX(CAP_SETUID)].effective |= CAP_TO_MASK(CAP_SETUID);
- capdata[CAP_TO_INDEX(CAP_SETGID)].effective |= CAP_TO_MASK(CAP_SETGID);
- capdata[CAP_TO_INDEX(CAP_SETUID)].permitted |= CAP_TO_MASK(CAP_SETUID);
- capdata[CAP_TO_INDEX(CAP_SETGID)].permitted |= CAP_TO_MASK(CAP_SETGID);
-
- if (capset(&capheader, &capdata[0]) < 0) {
- panic("Could not set capabilities: %s\n", strerror(errno));
- }
-
- pkgname = argv[1];
-
- /* get user_id from command line if provided */
- if ((argc >= 4) && !strcmp(argv[2], "--user")) {
- userId = atoi(argv[3]);
- if (userId < 0)
- panic("Negative user id %d is provided\n", userId);
- commandArgvOfs += 2;
- }
-
- /* retrieve package information from system (does setegid) */
- if (get_package_info(pkgname, userId, &info) < 0) {
- panic("Package '%s' is unknown\n", pkgname);
- }
-
- /* verify that user id is not too big. */
- if ((UID_MAX - info.uid) / AID_USER < (uid_t)userId) {
- panic("User id %d is too big\n", userId);
- }
-
- /* calculate user app ID. */
- userAppId = (AID_USER * userId) + info.uid;
-
- /* reject system packages */
- if (userAppId < AID_APP) {
- panic("Package '%s' is not an application\n", pkgname);
- }
-
- /* reject any non-debuggable package */
- if (!info.isDebuggable) {
- panic("Package '%s' is not debuggable\n", pkgname);
- }
-
- /* check that the data directory path is valid */
- if (check_data_path(info.dataDir, userAppId) < 0) {
- panic("Package '%s' has corrupt installation\n", pkgname);
- }
-
- /* Ensure that we change all real/effective/saved IDs at the
- * same time to avoid nasty surprises.
- */
- uid = gid = userAppId;
- if(setresgid(gid,gid,gid) || setresuid(uid,uid,uid)) {
- panic("Permission denied\n");
- }
-
- /* Required if caller has uid and gid all non-zero */
- memset(&capdata, 0, sizeof(capdata));
- if (capset(&capheader, &capdata[0]) < 0) {
- panic("Could not clear all capabilities: %s\n", strerror(errno));
- }
-
- if (selinux_android_setcontext(uid, 0, info.seinfo, pkgname) < 0) {
- panic("Could not set SELinux security context: %s\n", strerror(errno));
- }
-
- // cd into the data directory, and set $HOME correspondingly.
- if (TEMP_FAILURE_RETRY(chdir(info.dataDir)) < 0) {
- panic("Could not cd to package's data directory: %s\n", strerror(errno));
- }
- setenv("HOME", info.dataDir, 1);
-
- // Reset parts of the environment, like su would.
- setenv("PATH", _PATH_DEFPATH, 1);
- unsetenv("IFS");
-
- // Set the user-specific parts for this user.
- struct passwd* pw = getpwuid(uid);
- setenv("LOGNAME", pw->pw_name, 1);
- setenv("SHELL", pw->pw_shell, 1);
- setenv("USER", pw->pw_name, 1);
-
- /* User specified command for exec. */
- if ((argc >= commandArgvOfs + 1) &&
- (execvp(argv[commandArgvOfs], argv+commandArgvOfs) < 0)) {
- panic("exec failed for %s: %s\n", argv[commandArgvOfs], strerror(errno));
- }
-
- /* Default exec shell. */
- execlp("/system/bin/sh", "sh", NULL);
-
- panic("exec failed: %s\n", strerror(errno));
-}
diff --git a/run-as/run-as.cpp b/run-as/run-as.cpp
new file mode 100644
index 0000000..50b47b9
--- /dev/null
+++ b/run-as/run-as.cpp
@@ -0,0 +1,246 @@
+/*
+ * Copyright (C) 2010 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <errno.h>
+#include <error.h>
+#include <paths.h>
+#include <pwd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/capability.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <packagelistparser/packagelistparser.h>
+#include <private/android_filesystem_config.h>
+#include <selinux/android.h>
+
+// The purpose of this program is to run a command as a specific
+// application user-id. Typical usage is:
+//
+// run-as <package-name> <command> <args>
+//
+// The 'run-as' binary is installed with CAP_SETUID and CAP_SETGID file
+// capabilities, but will check the following:
+//
+// - that it is invoked from the 'shell' or 'root' user (abort otherwise)
+// - that '<package-name>' is the name of an installed and debuggable package
+// - that the package's data directory is well-formed
+//
+// If so, it will drop to the application's user id / group id, cd to the
+// package's data directory, then run the command there.
+//
+// This can be useful for a number of different things on production devices:
+//
+// - Allow application developers to look at their own application data
+// during development.
+//
+// - Run the 'gdbserver' binary executable to allow native debugging
+//
+
+static bool packagelist_parse_callback(pkg_info* this_package, void* userdata) {
+ pkg_info* p = reinterpret_cast<pkg_info*>(userdata);
+ if (strcmp(p->name, this_package->name) == 0) {
+ *p = *this_package;
+ return false; // Stop searching.
+ }
+ packagelist_free(this_package);
+ return true; // Keep searching.
+}
+
+static bool check_directory(const char* path, uid_t uid) {
+ struct stat st;
+ if (TEMP_FAILURE_RETRY(lstat(path, &st)) == -1) return false;
+
+ // /data/user/0 is a known safe symlink.
+ if (strcmp("/data/user/0", path) == 0) return true;
+
+ // Must be a real directory, not a symlink.
+ if (!S_ISDIR(st.st_mode)) return false;
+
+ // Must be owned by specific uid/gid.
+ if (st.st_uid != uid || st.st_gid != uid) return false;
+
+ // Must not be readable or writable by others.
+ if ((st.st_mode & (S_IROTH|S_IWOTH)) != 0) return false;
+
+ return true;
+}
+
+// This function is used to check the data directory path for safety.
+// We check that every sub-directory is owned by the 'system' user
+// and exists and is not a symlink. We also check that the full directory
+// path is properly owned by the user ID.
+static bool check_data_path(const char* data_path, uid_t uid) {
+ // The path should be absolute.
+ if (data_path[0] != '/') return false;
+
+ // Look for all sub-paths, we do that by finding
+ // directory separators in the input path and
+ // checking each sub-path independently.
+ for (int nn = 1; data_path[nn] != '\0'; nn++) {
+ char subpath[PATH_MAX];
+
+ /* skip non-separator characters */
+ if (data_path[nn] != '/') continue;
+
+ /* handle trailing separator case */
+ if (data_path[nn+1] == '\0') break;
+
+ /* found a separator, check that data_path is not too long. */
+ if (nn >= (int)(sizeof subpath)) return false;
+
+ /* reject any '..' subpath */
+ if (nn >= 3 &&
+ data_path[nn-3] == '/' &&
+ data_path[nn-2] == '.' &&
+ data_path[nn-1] == '.') {
+ return false;
+ }
+
+ /* copy to 'subpath', then check ownership */
+ memcpy(subpath, data_path, nn);
+ subpath[nn] = '\0';
+
+ if (!check_directory(subpath, AID_SYSTEM)) return false;
+ }
+
+ // All sub-paths were checked, now verify that the full data
+ // directory is owned by the application uid.
+ return check_directory(data_path, uid);
+}
+
+int main(int argc, char* argv[]) {
+ // Check arguments.
+ if (argc < 2) {
+ error(1, 0, "usage: run-as <package-name> [--user <uid>] <command> [<args>]\n");
+ }
+
+ // This program runs with CAP_SETUID and CAP_SETGID capabilities on Android
+ // production devices. Check user id of caller --- must be 'shell' or 'root'.
+ if (getuid() != AID_SHELL && getuid() != AID_ROOT) {
+ error(1, 0, "only 'shell' or 'root' users can run this program");
+ }
+
+ __user_cap_header_struct capheader;
+ __user_cap_data_struct capdata[2];
+ memset(&capheader, 0, sizeof(capheader));
+ memset(&capdata, 0, sizeof(capdata));
+ capheader.version = _LINUX_CAPABILITY_VERSION_3;
+ capdata[CAP_TO_INDEX(CAP_SETUID)].effective |= CAP_TO_MASK(CAP_SETUID);
+ capdata[CAP_TO_INDEX(CAP_SETGID)].effective |= CAP_TO_MASK(CAP_SETGID);
+ capdata[CAP_TO_INDEX(CAP_SETUID)].permitted |= CAP_TO_MASK(CAP_SETUID);
+ capdata[CAP_TO_INDEX(CAP_SETGID)].permitted |= CAP_TO_MASK(CAP_SETGID);
+ if (capset(&capheader, &capdata[0]) == -1) {
+ error(1, errno, "couldn't set capabilities");
+ }
+
+ char* pkgname = argv[1];
+ int cmd_argv_offset = 2;
+
+ // Get user_id from command line if provided.
+ int userId = 0;
+ if ((argc >= 4) && !strcmp(argv[2], "--user")) {
+ userId = atoi(argv[3]);
+ if (userId < 0) error(1, 0, "negative user id: %d", userId);
+ cmd_argv_offset += 2;
+ }
+
+ // Retrieve package information from system, switching egid so we can read the file.
+ gid_t old_egid = getegid();
+ if (setegid(AID_PACKAGE_INFO) == -1) error(1, errno, "setegid(AID_PACKAGE_INFO) failed");
+ pkg_info info;
+ memset(&info, 0, sizeof(info));
+ info.name = pkgname;
+ if (!packagelist_parse(packagelist_parse_callback, &info)) {
+ error(1, errno, "packagelist_parse failed");
+ }
+ if (info.uid == 0) {
+ error(1, 0, "unknown package: %s", pkgname);
+ }
+ if (setegid(old_egid) == -1) error(1, errno, "couldn't restore egid");
+
+ // Verify that user id is not too big.
+ if ((UID_MAX - info.uid) / AID_USER < (uid_t)userId) {
+ error(1, 0, "user id too big: %d", userId);
+ }
+
+ // Calculate user app ID.
+ uid_t userAppId = (AID_USER * userId) + info.uid;
+
+ // Reject system packages.
+ if (userAppId < AID_APP) {
+ error(1, 0, "package not an application: %s", pkgname);
+ }
+
+ // Reject any non-debuggable package.
+ if (!info.debuggable) {
+ error(1, 0, "package not debuggable: %s", pkgname);
+ }
+
+ // Check that the data directory path is valid.
+ if (!check_data_path(info.data_dir, userAppId)) {
+ error(1, 0, "package has corrupt installation: %s", pkgname);
+ }
+
+ // Ensure that we change all real/effective/saved IDs at the
+ // same time to avoid nasty surprises.
+ uid_t uid = userAppId;
+ uid_t gid = userAppId;
+ if (setresgid(gid, gid, gid) == -1) {
+ error(1, errno, "setresgid failed");
+ }
+ if (setresuid(uid, uid, uid) == -1) {
+ error(1, errno, "setresuid failed");
+ }
+
+ // Required if caller has uid and gid all non-zero.
+ memset(&capdata, 0, sizeof(capdata));
+ if (capset(&capheader, &capdata[0]) == -1) {
+ error(1, errno, "couldn't clear all capabilities");
+ }
+
+ if (selinux_android_setcontext(uid, 0, info.seinfo, pkgname) < 0) {
+ error(1, errno, "couldn't set SELinux security context");
+ }
+
+ // cd into the data directory, and set $HOME correspondingly.
+ if (TEMP_FAILURE_RETRY(chdir(info.data_dir)) == -1) {
+ error(1, errno, "couldn't chdir to package's data directory");
+ }
+ setenv("HOME", info.data_dir, 1);
+
+ // Reset parts of the environment, like su would.
+ setenv("PATH", _PATH_DEFPATH, 1);
+ unsetenv("IFS");
+
+ // Set the user-specific parts for this user.
+ passwd* pw = getpwuid(uid);
+ setenv("LOGNAME", pw->pw_name, 1);
+ setenv("SHELL", pw->pw_shell, 1);
+ setenv("USER", pw->pw_name, 1);
+
+ // User specified command for exec.
+ if ((argc >= cmd_argv_offset + 1) &&
+ (execvp(argv[cmd_argv_offset], argv+cmd_argv_offset) == -1)) {
+ error(1, errno, "exec failed for %s", argv[cmd_argv_offset]);
+ }
+
+ // Default exec shell.
+ execlp(_PATH_BSHELL, "sh", NULL);
+ error(1, errno, "exec failed");
+}