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Commit 1e59dcc2 authored by Tom Cherry's avatar Tom Cherry
Browse files

liblog: remove client side permissions checking 

There's no point in client side security checks in this library.  If a
process has access to these files, then they'll be able to do any of
these operations themselves.

Test: liblog unit tests
Change-Id: I75d4e1509eb8ff0ac4579f820a8968f4f5ad4e06
parent f5bad500

liblog/pmsg_reader.cpp

+24 −88
Original line number Original line Diff line number Diff line
@@ -62,59 +62,10 @@ static int pmsgAvailable(log_id_t logId) { 
  return -EBADF;

  return -EBADF;

}

}





/* Determine the credentials of the caller */

static bool uid_has_log_permission(uid_t uid) {

  return (uid == AID_SYSTEM) || (uid == AID_LOG) || (uid == AID_ROOT) || (uid == AID_LOGD);

}



static uid_t get_best_effective_uid() {

  uid_t euid;

  uid_t uid;

  gid_t gid;

  ssize_t i;

  static uid_t last_uid = (uid_t)-1;



  if (last_uid != (uid_t)-1) {

    return last_uid;

  }

  uid = __android_log_uid();

  if (uid_has_log_permission(uid)) {

    return last_uid = uid;

  }

  euid = geteuid();

  if (uid_has_log_permission(euid)) {

    return last_uid = euid;

  }

  gid = getgid();

  if (uid_has_log_permission(gid)) {

    return last_uid = gid;

  }

  gid = getegid();

  if (uid_has_log_permission(gid)) {

    return last_uid = gid;

  }

  i = getgroups((size_t)0, NULL);

  if (i > 0) {

    gid_t list[i];



    getgroups(i, list);

    while (--i >= 0) {

      if (uid_has_log_permission(list[i])) {

        return last_uid = list[i];

      }

    }

  }

  return last_uid = uid;

}



static int pmsgClear(struct android_log_logger* logger __unused,

static int pmsgClear(struct android_log_logger* logger __unused,

                     struct android_log_transport_context* transp __unused) {

                     struct android_log_transport_context* transp __unused) {

  if (uid_has_log_permission(get_best_effective_uid())) {

  return unlink("/sys/fs/pstore/pmsg-ramoops-0");

  return unlink("/sys/fs/pstore/pmsg-ramoops-0");

}

}

  errno = EPERM;

  return -1;

}





/*

/*

 * returns the logger version

 * returns the logger version
@@ -128,14 +79,12 @@ static int pmsgRead(struct android_log_logger_list* logger_list, 
                    struct android_log_transport_context* transp, struct log_msg* log_msg) {

                    struct android_log_transport_context* transp, struct log_msg* log_msg) {

  ssize_t ret;

  ssize_t ret;

  off_t current, next;

  off_t current, next;

  uid_t uid;

  struct __attribute__((__packed__)) {

  struct __attribute__((__packed__)) {

    android_pmsg_log_header_t p;

    android_pmsg_log_header_t p;

    android_log_header_t l;

    android_log_header_t l;

    uint8_t prio;

    uint8_t prio;

  } buf;

  } buf;

  static uint8_t preread_count;

  static uint8_t preread_count;

  bool is_system;





  memset(log_msg, 0, sizeof(*log_msg));

  memset(log_msg, 0, sizeof(*log_msg));
@@ -195,10 +144,7 @@ static int pmsgRead(struct android_log_logger_list* logger_list, 
          ((logger_list->start.tv_sec != buf.l.realtime.tv_sec) ||

          ((logger_list->start.tv_sec != buf.l.realtime.tv_sec) ||

           (logger_list->start.tv_nsec <= buf.l.realtime.tv_nsec)))) &&

           (logger_list->start.tv_nsec <= buf.l.realtime.tv_nsec)))) &&

        (!logger_list->pid || (logger_list->pid == buf.p.pid))) {

        (!logger_list->pid || (logger_list->pid == buf.p.pid))) {

      uid = get_best_effective_uid();

      char* msg = log_msg->entry_v4.msg;

      is_system = uid_has_log_permission(uid);

      if (is_system || (uid == buf.p.uid)) {

        char* msg = is_system ? log_msg->entry_v4.msg : log_msg->entry_v3.msg;

      *msg = buf.prio;

      *msg = buf.prio;

      fd = atomic_load(&transp->context.fd);

      fd = atomic_load(&transp->context.fd);

      if (fd <= 0) {

      if (fd <= 0) {
@@ -213,20 +159,16 @@ static int pmsgRead(struct android_log_logger_list* logger_list, 
      }

      }





      log_msg->entry_v4.len = buf.p.len - sizeof(buf) + sizeof(buf.prio);

      log_msg->entry_v4.len = buf.p.len - sizeof(buf) + sizeof(buf.prio);

        log_msg->entry_v4.hdr_size =

      log_msg->entry_v4.hdr_size = sizeof(log_msg->entry_v4);

            is_system ? sizeof(log_msg->entry_v4) : sizeof(log_msg->entry_v3);

      log_msg->entry_v4.pid = buf.p.pid;

      log_msg->entry_v4.pid = buf.p.pid;

      log_msg->entry_v4.tid = buf.l.tid;

      log_msg->entry_v4.tid = buf.l.tid;

      log_msg->entry_v4.sec = buf.l.realtime.tv_sec;

      log_msg->entry_v4.sec = buf.l.realtime.tv_sec;

      log_msg->entry_v4.nsec = buf.l.realtime.tv_nsec;

      log_msg->entry_v4.nsec = buf.l.realtime.tv_nsec;

      log_msg->entry_v4.lid = buf.l.id;

      log_msg->entry_v4.lid = buf.l.id;

        if (is_system) {

      log_msg->entry_v4.uid = buf.p.uid;

      log_msg->entry_v4.uid = buf.p.uid;

        }





      return ret + sizeof(buf.prio) + log_msg->entry_v4.hdr_size;

      return ret + sizeof(buf.prio) + log_msg->entry_v4.hdr_size;

    }

    }

    }





    fd = atomic_load(&transp->context.fd);

    fd = atomic_load(&transp->context.fd);

    if (fd <= 0) {

    if (fd <= 0) {
@@ -273,13 +215,7 @@ ssize_t __android_log_pmsg_file_read(log_id_t logId, char prio, const char* pref 
  struct android_log_transport_context transp;

  struct android_log_transport_context transp;

  struct content {

  struct content {

    struct listnode node;

    struct listnode node;

    union {

    struct logger_entry_v4 entry;

    struct logger_entry_v4 entry;

      struct logger_entry_v4 entry_v4;

      struct logger_entry_v3 entry_v3;

      struct logger_entry_v2 entry_v2;

      struct logger_entry entry_v1;

    };

  } * content;

  } * content;

  struct names {

  struct names {

    struct listnode node;

    struct listnode node;