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Commit 978fd0ea authored by Mark Salyzyn's avatar Mark Salyzyn
Browse files

init: service file command only opens existing files 

Mixing open or create, along with attribute(MAC) and permissions(DAC)
is a security and confusion issue.

Fix an issue where fcntl F_SETFD was called to clear O_NONBLOCK, when
it should have been F_SETFL.  Did not present a problem because the
current user of this feature does writes and control messages only.

Test: gTest logd-unit-tests and check dmesg for logd content.
Bug: 32450474
Bug: 33242020
Change-Id: I23cb9a9be5ddb7e8e9c58c79838bc07536e766e6
parent e218fc67

init/Android.mk

+0 −1
Original line number Diff line number Diff line
@@ -126,7 +126,6 @@ LOCAL_SRC_FILES := \ 
LOCAL_SHARED_LIBRARIES += \

    libcutils \

    libbase \

    libselinux \



LOCAL_STATIC_LIBRARIES := libinit

LOCAL_SANITIZE := integer

init/descriptors.cpp

+26 −5
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ 
#include <unistd.h>



#include <android-base/stringprintf.h>

#include <android-base/unique_fd.h>

#include <cutils/android_get_control_file.h>

#include <cutils/sockets.h>
@@ -89,14 +90,34 @@ const std::string SocketInfo::key() const { 


FileInfo::FileInfo(const std::string& name, const std::string& type, uid_t uid,

                   gid_t gid, int perm, const std::string& context)

        // defaults OK for uid,..., they are ignored for this class.

        : DescriptorInfo(name, type, uid, gid, perm, context) {

}



int FileInfo::Create(const std::string& context) const {

  int flags = ((type() == "r" ? O_RDONLY :

                (type() == "w" ? (O_WRONLY | O_CREAT) :

                 (O_RDWR | O_CREAT))));

  return create_file(name().c_str(), flags, perm(), uid(), gid(), context.c_str());

int FileInfo::Create(const std::string&) const {

  int flags = (type() == "r") ? O_RDONLY :

              (type() == "w") ? O_WRONLY :

                                O_RDWR;



  // Make sure we do not block on open (eg: devices can chose to block on

  // carrier detect).  Our intention is never to delay launch of a service

  // for such a condition.  The service can perform its own blocking on

  // carrier detect.

  android::base::unique_fd fd(TEMP_FAILURE_RETRY(open(name().c_str(),

                                                      flags | O_NONBLOCK)));



  if (fd < 0) {

    PLOG(ERROR) << "Failed to open file '" << name().c_str() << "'";

    return -1;

  }



  // Fixup as we set O_NONBLOCK for open, the intent for fd is to block reads.

  fcntl(fd, F_SETFL, flags);



  LOG(INFO) << "Opened file '" << name().c_str() << "'"

            << ", flags " << std::oct << flags << std::dec;



  return fd.release();

}



const std::string FileInfo::key() const {

init/readme.txt

+4 −7
Original line number Diff line number Diff line
@@ -148,13 +148,10 @@ socket <name> <type> <perm> [ <user> [ <group> [ <seclabel> ] ] ] 
  seclabel or computed based on the service executable file security context.

  For native executables see libcutils android_get_control_socket().



file <path> <type> <perm> [ <user> [ <group> [ <seclabel> ] ] ]

  Open/Create a file path and pass its fd to the launched process.  <type> must

  be "r", "w" or "rw".  User and group default to 0.  'seclabel' is the SELinux

  security context for the file if it must be created.  It defaults to the

  service security context, as specified by seclabel or computed based on the

  service executable file security context.  For native executables see

  libcutils android_get_control_file().

file <path> <type>

  Open a file path and pass its fd to the launched process.  <type> must be

  "r", "w" or "rw".  For native executables see libcutils

  android_get_control_file().



user <username>

  Change to 'username' before exec'ing this service.

init/service.cpp

+1 −1
Original line number Diff line number Diff line
@@ -526,7 +526,7 @@ Service::OptionParserMap::Map& Service::OptionParserMap::map() const { 
        {"seclabel",    {1,     1,    &Service::ParseSeclabel}},

        {"setenv",      {2,     2,    &Service::ParseSetenv}},

        {"socket",      {3,     6,    &Service::ParseSocket}},

        {"file",        {2,     6,    &Service::ParseFile}},

        {"file",        {2,     2,    &Service::ParseFile}},

        {"user",        {1,     1,    &Service::ParseUser}},

        {"writepid",    {1,     kMax, &Service::ParseWritepid}},

    };

init/util.cpp

+0 −63
Original line number Diff line number Diff line
@@ -160,69 +160,6 @@ out_unlink: 
    return -1;

}



/*

 * create_file - opens and creates a file as dictated in init.rc.

 * This file is inherited by the daemon. We communicate the file

 * descriptor's value via the environment variable ANDROID_FILE_<basename>

 */

int create_file(const char *path, int flags, mode_t perm, uid_t uid,

                  gid_t gid, const char *filecon)

{

    char *secontext = NULL;



    if (filecon) {

        if (setsockcreatecon(filecon) == -1) {

            PLOG(ERROR) << "setsockcreatecon(\"" << filecon << "\") failed";

            return -1;

        }

    } else if (sehandle) {

        if (selabel_lookup(sehandle, &secontext, path, perm) != -1) {

            if (setfscreatecon(secontext) == -1) {

                freecon(secontext); // does not upset errno value

                PLOG(ERROR) << "setfscreatecon(\"" << secontext << "\") failed";

                return -1;

            }

        }

    }



    android::base::unique_fd fd(TEMP_FAILURE_RETRY(open(path, flags | O_NDELAY, perm)));

    int savederrno = errno;



    if (filecon) {

        setsockcreatecon(NULL);

        lsetfilecon(path, filecon);

    } else {

        setfscreatecon(NULL);

        freecon(secontext);

    }



    if (fd < 0) {

        errno = savederrno;

        PLOG(ERROR) << "Failed to open/create file '" << path << "'";

        return -1;

    }



    if (!(flags & O_NDELAY)) fcntl(fd, F_SETFD, flags);



    if (lchown(path, uid, gid)) {

        PLOG(ERROR) << "Failed to lchown file '" << path << "'";

        return -1;

    }

    if (perm != static_cast<mode_t>(-1)) {

        if (fchmodat(AT_FDCWD, path, perm, AT_SYMLINK_NOFOLLOW)) {

            PLOG(ERROR) << "Failed to fchmodat file '" << path << "'";

            return -1;

        }

    }



    LOG(INFO) << "Created file '" << path << "'"

              << ", mode " << std::oct << perm << std::dec

              << ", user " << uid

              << ", group " << gid;



    return fd.release();

}



bool read_file(const char* path, std::string* content) {

    content->clear();