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Commit 1b4e7328 authored by Paul Crowley's avatar Paul Crowley
Browse files

Straighten out do_mkdir 

Use lstat(), and then make only the system calls needed to fix the
directory up.

Bug: 140027478
Test: boots twice, no worrying log messages.
Change-Id: I1c1445baae3ec1c1ce17626ede388aa04d5f7781
parent 285e5d6d

init/builtins.cpp

+47 −34
Original line number Diff line number Diff line
@@ -357,51 +357,64 @@ static Result<void> do_interface_stop(const BuiltinArguments& args) { 
// mkdir <path> [mode] [owner] [group]

static Result<void> do_mkdir(const BuiltinArguments& args) {

    mode_t mode = 0755;

    if (args.size() >= 3) {

        mode = std::strtoul(args[2].c_str(), 0, 8);

    }



    if (!make_dir(args[1], mode)) {

        /* chmod in case the directory already exists */

        if (errno == EEXIST) {

            if (fchmodat(AT_FDCWD, args[1].c_str(), mode, AT_SYMLINK_NOFOLLOW) == -1) {

                return ErrnoError() << "fchmodat() failed";

            }

        } else {

            return ErrnoErrorIgnoreEnoent() << "mkdir() failed";

        }

    }



    if (args.size() >= 4) {

        auto uid = DecodeUid(args[3]);

        if (!uid) {

            return Error() << "Unable to decode UID for '" << args[3] << "': " << uid.error();

        }

    Result<uid_t> uid = -1;

    Result<gid_t> gid = -1;



        if (args.size() == 5) {

    switch (args.size()) {

        case 5:

            gid = DecodeUid(args[4]);

            if (!gid) {

                return Error() << "Unable to decode GID for '" << args[4] << "': " << gid.error();

            }

            FALLTHROUGH_INTENDED;

        case 4:

            uid = DecodeUid(args[3]);

            if (!uid) {

                return Error() << "Unable to decode UID for '" << args[3] << "': " << uid.error();

            }



        if (lchown(args[1].c_str(), *uid, *gid) == -1) {

            return ErrnoError() << "lchown failed";

            FALLTHROUGH_INTENDED;

        case 3:

            mode = std::strtoul(args[2].c_str(), 0, 8);

            FALLTHROUGH_INTENDED;

        case 2:

            break;

        default:

            return Error() << "Unexpected argument count: " << args.size();

    }



        /* chown may have cleared S_ISUID and S_ISGID, chmod again */

        if (mode & (S_ISUID | S_ISGID)) {

            if (fchmodat(AT_FDCWD, args[1].c_str(), mode, AT_SYMLINK_NOFOLLOW) == -1) {

                return ErrnoError() << "fchmodat failed";

    std::string target = args[1];

    struct stat mstat;

    if (lstat(target.c_str(), &mstat) != 0) {

        if (errno != ENOENT) {

            return ErrnoError() << "lstat() failed on " << target;

        }

        if (!make_dir(target, mode)) {

            return ErrnoErrorIgnoreEnoent() << "mkdir() failed on " << target;

        }

        if (lstat(target.c_str(), &mstat) != 0) {

            return ErrnoError() << "lstat() failed on new " << target;

        }

    }

    if (!S_ISDIR(mstat.st_mode)) {

        return Error() << "Not a directory on " << target;

    }

    bool needs_chmod = (mstat.st_mode & ~S_IFMT) != mode;

    if ((*uid != static_cast<uid_t>(-1) && *uid != mstat.st_uid) ||

        (*gid != static_cast<gid_t>(-1) && *gid != mstat.st_gid)) {

        if (lchown(target.c_str(), *uid, *gid) == -1) {

            return ErrnoError() << "lchown failed on " << target;

        }

        // chown may have cleared S_ISUID and S_ISGID, chmod again

        needs_chmod = true;

    }

    if (needs_chmod) {

        if (fchmodat(AT_FDCWD, target.c_str(), mode, AT_SYMLINK_NOFOLLOW) == -1) {

            return ErrnoError() << "fchmodat() failed on " << target;

        }

    }



    if (fscrypt_is_native()) {

        if (fscrypt_set_directory_policy(args[1])) {

        if (fscrypt_set_directory_policy(target)) {

            return reboot_into_recovery(

                {"--prompt_and_wipe_data", "--reason=set_policy_failed:"s + args[1]});

                    {"--prompt_and_wipe_data", "--reason=set_policy_failed:"s + target});

        }

    }

    return {};