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Commit 3a60e68b authored by Yabin Cui's avatar Yabin Cui
Browse files

run-as: add shared app gid in supplementary groups. 

This is to read profile guide compiled oat files of debuggable apps, which is
needed by simpleperf for profiling.

Bug: none
Test: run run-as manually.
Change-Id: I8ec8897b882be650f02124413c7d20ed8b1b444b
parent 37b5edf6

run-as/run-as.cpp

+22 −1
Original line number Diff line number Diff line
@@ -26,6 +26,7 @@ 
#include <unistd.h>



#include <string>

#include <vector>



#include <libminijail.h>

#include <scoped_minijail.h>
@@ -131,6 +132,25 @@ static bool check_data_path(const char* data_path, uid_t uid) { 
  return check_directory(data_path, uid);

}



std::vector<gid_t> get_supplementary_gids(uid_t userAppId) {

  std::vector<gid_t> gids;

  int size = getgroups(0, &gids[0]);

  if (size < 0) {

    error(1, errno, "getgroups failed");

  }

  gids.resize(size);

  size = getgroups(size, &gids[0]);

  if (size != static_cast<int>(gids.size())) {

    error(1, errno, "getgroups failed");

  }

  // Profile guide compiled oat files (like /data/app/xxx/oat/arm64/base.odex) are not readable

  // worldwide (DEXOPT_PUBLIC flag isn't set). To support reading them (needed by simpleperf for

  // profiling), add shared app gid to supplementary groups.

  gid_t shared_app_gid = userAppId % AID_USER_OFFSET - AID_APP_START + AID_SHARED_GID_START;

  gids.push_back(shared_app_gid);

  return gids;

}



int main(int argc, char* argv[]) {

  // Check arguments.

  if (argc < 2) {
@@ -210,10 +230,11 @@ int main(int argc, char* argv[]) { 
  // same time to avoid nasty surprises.

  uid_t uid = userAppId;

  uid_t gid = userAppId;

  std::vector<gid_t> supplementary_gids = get_supplementary_gids(userAppId);

  ScopedMinijail j(minijail_new());

  minijail_change_uid(j.get(), uid);

  minijail_change_gid(j.get(), gid);

  minijail_keep_supplementary_gids(j.get());

  minijail_set_supplementary_gids(j.get(), supplementary_gids.size(), supplementary_gids.data());

  minijail_enter(j.get());



  std::string seinfo = std::string(info.seinfo) + ":fromRunAs";