Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 1c7acfdb authored by Samiul Islam's avatar Samiul Islam
Browse files

Create utility method for calculating supplemental_uid from app_uid 

Every app will now have a corresponding supplemental process associated
with it. We need an utility method to map one to the other.

Implementation details: supplemental process uid will be between range
20k-30k. As such, it will be a 10k offset from app id. See ag/16621743.

Bug: 211763739
Test: atest installd_service_test
Ignore-AOSP-First: Feature is being developed in internal branch
Change-Id: I2b6d6b086985bcb24c837eaa95a937d429d6a583
parent 9d656230

libcutils/include/cutils/multiuser.h

+1 −0
Original line number Diff line number Diff line
@@ -30,6 +30,7 @@ extern userid_t multiuser_get_user_id(uid_t uid); 
extern appid_t multiuser_get_app_id(uid_t uid);



extern uid_t multiuser_get_uid(userid_t user_id, appid_t app_id);

extern uid_t multiuser_get_supplemental_uid(userid_t user_id, appid_t app_id);



extern gid_t multiuser_get_cache_gid(userid_t user_id, appid_t app_id);

extern gid_t multiuser_get_ext_gid(userid_t user_id, appid_t app_id);

libcutils/include/private/android_filesystem_config.h

+4 −0
Original line number Diff line number Diff line
@@ -210,6 +210,10 @@ 
 */

#define AID_OVERFLOWUID 65534 /* unmapped user in the user namespace */



/* use the ranges below to determine whether a process is supplemental */

#define AID_SUPPLEMENTAL_PROCESS_START 20000 /* start of uids allocated to supplemental process */

#define AID_SUPPLEMENTAL_PROCESS_END 29999   /* end of uids allocated to supplemental process */



/* use the ranges below to determine whether a process is isolated */

#define AID_ISOLATED_START 90000 /* start of uids for fully isolated sandboxed processes */

#define AID_ISOLATED_END 99999   /* end of uids for fully isolated sandboxed processes */

libcutils/multiuser.cpp

+9 −0
Original line number Diff line number Diff line
@@ -29,6 +29,15 @@ uid_t multiuser_get_uid(userid_t user_id, appid_t app_id) { 
    return (user_id * AID_USER_OFFSET) + (app_id % AID_USER_OFFSET);

}



uid_t multiuser_get_supplemental_uid(userid_t user_id, appid_t app_id) {

    int supplementalProcessOffset = AID_SUPPLEMENTAL_PROCESS_START - AID_APP_START;

    if (app_id >= AID_APP_START && app_id <= AID_APP_END) {

        return (user_id * AID_USER_OFFSET) + (app_id % AID_USER_OFFSET) + supplementalProcessOffset;

    } else {

        return -1;

    }

}



gid_t multiuser_get_cache_gid(userid_t user_id, appid_t app_id) {

    if (app_id >= AID_APP_START && app_id <= AID_APP_END) {

        return multiuser_get_uid(user_id, (app_id - AID_APP_START) + AID_CACHE_GID_START);

libcutils/multiuser_test.cpp

+17 −0
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ 
#include <gtest/gtest.h>



static constexpr auto ERR_GID = static_cast<gid_t>(-1);

static constexpr auto ERR_UID = static_cast<uid_t>(-1);



TEST(MultiuserTest, TestMerge) {

    EXPECT_EQ(0U, multiuser_get_uid(0, 0));
@@ -30,6 +31,22 @@ TEST(MultiuserTest, TestMerge) { 
    EXPECT_EQ(1050000U, multiuser_get_uid(10, 50000));

}



TEST(MultiuserTest, TestSupplementalUid) {

    EXPECT_EQ(ERR_UID, multiuser_get_supplemental_uid(0, 0));

    EXPECT_EQ(ERR_UID, multiuser_get_supplemental_uid(0, 1000));

    EXPECT_EQ(20000U, multiuser_get_supplemental_uid(0, 10000));

    EXPECT_EQ(25000U, multiuser_get_supplemental_uid(0, 15000));

    EXPECT_EQ(29999U, multiuser_get_supplemental_uid(0, 19999));

    EXPECT_EQ(ERR_UID, multiuser_get_supplemental_uid(0, 50000));



    EXPECT_EQ(ERR_UID, multiuser_get_supplemental_uid(10, 0));

    EXPECT_EQ(ERR_UID, multiuser_get_supplemental_uid(10, 1000));

    EXPECT_EQ(1020000U, multiuser_get_supplemental_uid(10, 10000));

    EXPECT_EQ(1025000U, multiuser_get_supplemental_uid(10, 15000));

    EXPECT_EQ(ERR_UID, multiuser_get_supplemental_uid(10, 20000));

    EXPECT_EQ(ERR_UID, multiuser_get_supplemental_uid(10, 50000));

}



TEST(MultiuserTest, TestSplitUser) {

    EXPECT_EQ(0U, multiuser_get_user_id(0));

    EXPECT_EQ(0U, multiuser_get_user_id(1000));