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Commit da31778f authored by Oleksiy Vyalov's avatar Oleksiy Vyalov
Browse files

Extend run-as with optional --user argument. 

1. Calculate AID for spawned process as (100000 * $user) + uid_from_packages.list
2. Use /data/user/$user/$packageDir as a root of a new process if $user != 0.

Change-Id: I761dfb481114bd51e5a950307fcaf403e96eef10
parent 9187fb59

run-as/package.c

+16 −2
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ 
*/

#include <errno.h>

#include <fcntl.h>

#include <stdio.h>

#include <string.h>

#include <sys/mman.h>

#include <sys/stat.h>
@@ -421,7 +422,7 @@ parse_positive_decimal(const char** pp, const char* end) 
 * If the package database is corrupted, return -1 and set errno to EINVAL

 */

int

get_package_info(const char* pkgName, PackageInfo *info)

get_package_info(const char* pkgName, uid_t userId, PackageInfo *info)

{

    char*        buffer;

    size_t       buffer_len;
@@ -506,7 +507,20 @@ get_package_info(const char* pkgName, PackageInfo *info) 
        if (q == p)

            goto BAD_FORMAT;



        /* If userId == 0 (i.e. user is device owner) we can use dataDir value

         * from packages.list, otherwise compose data directory as

         * /data/user/$uid/$packageId

         */

        if (userId == 0) {

            p = string_copy(info->dataDir, sizeof info->dataDir, p, q - p);

        } else {

            snprintf(info->dataDir,

                     sizeof info->dataDir,

                     "/data/user/%d/%s",

                     userId,

                     pkgName);

            p = q;

        }



        /* skip spaces */

        if (parse_spaces(&p, end) < 0)

run-as/package.h

+4 −2
Original line number Diff line number Diff line
@@ -33,9 +33,11 @@ typedef struct { 
    char   seinfo[PATH_MAX];

} PackageInfo;



/* see documentation in package.c for these functiosn */

/* see documentation in package.c for these functions */



extern int  get_package_info(const char* packageName, PackageInfo*  info);

extern int  get_package_info(const char* packageName,

                             uid_t userId,

                             PackageInfo*  info);



extern int  check_data_path(const char* dataDir, uid_t uid);

run-as/run-as.c

+28 −9
Original line number Diff line number Diff line
@@ -102,13 +102,14 @@ panic(const char* format, ...) 
static void

usage(void)

{

    panic("Usage:\n    " PROGNAME " <package-name> <command> [<args>]\n");

    panic("Usage:\n    " PROGNAME " <package-name> [--user <uid>] <command> [<args>]\n");

}



int main(int argc, char **argv)

{

    const char* pkgname;

    int myuid, uid, gid;

    uid_t myuid, uid, gid, userAppId = 0;

    int commandArgvOfs = 2, userId = 0;

    PackageInfo info;

    struct __user_cap_header_struct capheader;

    struct __user_cap_data_struct capdata[2];
@@ -136,14 +137,31 @@ int main(int argc, char **argv) 
        panic("Could not set capabilities: %s\n", strerror(errno));

    }



    /* retrieve package information from system (does setegid) */

    pkgname = argv[1];

    if (get_package_info(pkgname, &info) < 0) {



    /* get user_id from command line if provided */

    if ((argc >= 4) && !strcmp(argv[2], "--user")) {

        userId = atoi(argv[3]);

        if (userId < 0)

            panic("Negative user id %d is provided\n", userId);

        commandArgvOfs += 2;

    }



    /* retrieve package information from system (does setegid) */

    if (get_package_info(pkgname, userId, &info) < 0) {

        panic("Package '%s' is unknown\n", pkgname);

    }



    /* verify that user id is not too big. */

    if ((UID_MAX - info.uid) / AID_USER < (uid_t)userId) {

        panic("User id %d is too big\n", userId);

    }



    /* calculate user app ID. */

    userAppId = (AID_USER * userId) + info.uid;



    /* reject system packages */

    if (info.uid < AID_APP) {

    if (userAppId < AID_APP) {

        panic("Package '%s' is not an application\n", pkgname);

    }
@@ -153,14 +171,14 @@ int main(int argc, char **argv) 
    }



    /* check that the data directory path is valid */

    if (check_data_path(info.dataDir, info.uid) < 0) {

    if (check_data_path(info.dataDir, userAppId) < 0) {

        panic("Package '%s' has corrupt installation\n", pkgname);

    }



    /* Ensure that we change all real/effective/saved IDs at the

     * same time to avoid nasty surprises.

     */

    uid = gid = info.uid;

    uid = gid = userAppId;

    if(setresgid(gid,gid,gid) || setresuid(uid,uid,uid)) {

        panic("Permission denied\n");

    }
@@ -181,8 +199,9 @@ int main(int argc, char **argv) 
    }



    /* User specified command for exec. */

    if ((argc >= 3) && (execvp(argv[2], argv+2) < 0)) {

        panic("exec failed for %s: %s\n", argv[2], strerror(errno));

    if ((argc >= commandArgvOfs + 1) &&

        (execvp(argv[commandArgvOfs], argv+commandArgvOfs) < 0)) {

        panic("exec failed for %s: %s\n", argv[commandArgvOfs], strerror(errno));

    }



    /* Default exec shell. */