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Commit 3aa261c0 authored by Daniel Rosenberg's avatar Daniel Rosenberg
Browse files

Revert "Revert "sdcard: Support sdcardfs"" 

Issue resolved by commit
6855c48093e109c92df39340a8355a3be2540b8e
"Skip mounting sdcardfs in core mode."

This reverts commit f8fccd2f.

Bug: 27932087
Change-Id: Ibdb72ad16a1e6c3a01edcb03d003c42de7a03cd6
parent f8fccd2f

sdcard/sdcard.c

+104 −1
Original line number Diff line number Diff line
@@ -1894,6 +1894,105 @@ static void run(const char* source_path, const char* label, uid_t uid, 
    exit(1);

}



static int sdcardfs_setup(const char *source_path, const char *dest_path, uid_t fsuid,

                        gid_t fsgid, bool multi_user, userid_t userid, gid_t gid, mode_t mask) {

    char opts[256];



    snprintf(opts, sizeof(opts),

            "fsuid=%d,fsgid=%d,%smask=%d,userid=%d,gid=%d",

            fsuid, fsgid, multi_user?"multiuser,":"", mask, userid, gid);



    if (mount(source_path, dest_path, "sdcardfs",

                        MS_NOSUID | MS_NODEV | MS_NOEXEC | MS_NOATIME, opts) != 0) {

        ERROR("failed to mount sdcardfs filesystem: %s\n", strerror(errno));

        return -1;

    }



    return 0;

}



static void run_sdcardfs(const char* source_path, const char* label, uid_t uid,

        gid_t gid, userid_t userid, bool multi_user, bool full_write) {

    char dest_path_default[PATH_MAX];

    char dest_path_read[PATH_MAX];

    char dest_path_write[PATH_MAX];

    char obb_path[PATH_MAX];

    snprintf(dest_path_default, PATH_MAX, "/mnt/runtime/default/%s", label);

    snprintf(dest_path_read, PATH_MAX, "/mnt/runtime/read/%s", label);

    snprintf(dest_path_write, PATH_MAX, "/mnt/runtime/write/%s", label);



    umask(0);

    if (multi_user) {

        /* Multi-user storage is fully isolated per user, so "other"

         * permissions are completely masked off. */

        if (sdcardfs_setup(source_path, dest_path_default, uid, gid, multi_user, userid,

                                                      AID_SDCARD_RW, 0006)

                || sdcardfs_setup(source_path, dest_path_read, uid, gid, multi_user, userid,

                                                      AID_EVERYBODY, 0027)

                || sdcardfs_setup(source_path, dest_path_write, uid, gid, multi_user, userid,

                                                      AID_EVERYBODY, full_write ? 0007 : 0027)) {

            ERROR("failed to fuse_setup\n");

            exit(1);

        }

    } else {

        /* Physical storage is readable by all users on device, but

         * the Android directories are masked off to a single user

         * deep inside attr_from_stat(). */

        if (sdcardfs_setup(source_path, dest_path_default, uid, gid, multi_user, userid,

                                                      AID_SDCARD_RW, 0006)

                || sdcardfs_setup(source_path, dest_path_read, uid, gid, multi_user, userid,

                                                      AID_EVERYBODY, full_write ? 0027 : 0022)

                || sdcardfs_setup(source_path, dest_path_write, uid, gid, multi_user, userid,

                                                      AID_EVERYBODY, full_write ? 0007 : 0022)) {

            ERROR("failed to fuse_setup\n");

            exit(1);

        }

    }



    /* Drop privs */

    if (setgroups(sizeof(kGroups) / sizeof(kGroups[0]), kGroups) < 0) {

        ERROR("cannot setgroups: %s\n", strerror(errno));

        exit(1);

    }

    if (setgid(gid) < 0) {

        ERROR("cannot setgid: %s\n", strerror(errno));

        exit(1);

    }

    if (setuid(uid) < 0) {

        ERROR("cannot setuid: %s\n", strerror(errno));

        exit(1);

    }



    if (multi_user) {

        snprintf(obb_path, sizeof(obb_path), "%s/obb", source_path);

        fs_prepare_dir(&obb_path[0], 0775, uid, gid);

    }



    exit(0);

}



static bool supports_sdcardfs(void) {

    FILE *fp;

    char *buf = NULL;

    size_t buflen = 0;



    fp = fopen("/proc/filesystems", "r");

    if (!fp) {

        ERROR("Could not read /proc/filesystems, error: %s\n", strerror(errno));

        return false;

    }

    while ((getline(&buf, &buflen, fp)) > 0) {

        if (strstr(buf, "sdcardfs\n")) {

            free(buf);

            fclose(fp);

            return true;

        }

    }

    free(buf);

    fclose(fp);

    return false;

}



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

    const char *source_path = NULL;

    const char *label = NULL;
@@ -1966,6 +2065,10 @@ int main(int argc, char **argv) { 
        sleep(1);

    }



    if (supports_sdcardfs()) {

        run_sdcardfs(source_path, label, uid, gid, userid, multi_user, full_write);

    } else {

        run(source_path, label, uid, gid, userid, multi_user, full_write);

    }

    return 1;

}