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platform_system_core
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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
This commit is contained in:
Yabin Cui 2019-01-10 15:08:22 -08:00
parent 37b5edf61b
commit 3a60e68b72
1 changed files with 22 additions and 1 deletions
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23
run-as/run-as.cpp
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@ -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";