From patchwork Tue Sep 1 20:27:33 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Laurent Vivier X-Patchwork-Id: 513052 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 2F1761401C7 for ; Wed, 2 Sep 2015 06:28:07 +1000 (AEST) Received: from localhost ([::1]:58342 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZWsA1-0002Co-Bh for incoming@patchwork.ozlabs.org; Tue, 01 Sep 2015 16:28:05 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:33271) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZWs9h-0001nS-42 for qemu-devel@nongnu.org; Tue, 01 Sep 2015 16:27:46 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZWs9d-0001OT-Nx for qemu-devel@nongnu.org; Tue, 01 Sep 2015 16:27:45 -0400 Received: from smtp4-g21.free.fr ([212.27.42.4]:19841) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZWs9d-0001O7-IT for qemu-devel@nongnu.org; Tue, 01 Sep 2015 16:27:41 -0400 Received: from Quad.localdomain (unknown [78.238.229.36]) by smtp4-g21.free.fr (Postfix) with ESMTPS id 7C5884C804F; Tue, 1 Sep 2015 22:27:39 +0200 (CEST) From: Laurent Vivier To: riku.voipio@iki.fi, qemu-devel@nongnu.org, peter.maydell@linaro.org Date: Tue, 1 Sep 2015 22:27:33 +0200 Message-Id: <1441139253-6578-1-git-send-email-laurent@vivier.eu> X-Mailer: git-send-email 2.4.3 X-detected-operating-system: by eggs.gnu.org: Windows NT kernel [generic] [fuzzy] X-Received-From: 212.27.42.4 Cc: Laurent Vivier Subject: [Qemu-devel] [PATCH v2] linux-user: add name_to_handle_at/open_by_handle_at X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org This patch allows to run example given by open_by_handle_at(2): The following shell session demonstrates the use of these two programs: $ echo 'Can you please think about it?' > cecilia.txt $ ./t_name_to_handle_at cecilia.txt > fh $ ./t_open_by_handle_at < fh open_by_handle_at: Operation not permitted $ sudo ./t_open_by_handle_at < fh # Need CAP_SYS_ADMIN Read 31 bytes $ rm cecilia.txt Now we delete and (quickly) re-create the file so that it has the same content and (by chance) the same inode.[...] $ stat --printf="%i\n" cecilia.txt # Display inode number 4072121 $ rm cecilia.txt $ echo 'Can you please think about it?' > cecilia.txt $ stat --printf="%i\n" cecilia.txt # Check inode number 4072121 $ sudo ./t_open_by_handle_at < fh open_by_handle_at: Stale NFS file handle See the man page for source code. Signed-off-by: Laurent Vivier Reviewed-by: Peter Maydell --- v2: Rename function parameters, swap fh->handle_type in both functions, When I have re-tested the patch I have found a bug in the size of the data, so I fix this too (handle_bytes is the size of f_handle[] only, not of the whole structure) linux-user/syscall.c | 98 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 98 insertions(+) diff --git a/linux-user/syscall.c b/linux-user/syscall.c index f62c698..8a17351 100644 --- a/linux-user/syscall.c +++ b/linux-user/syscall.c @@ -5246,6 +5246,94 @@ static int do_futex(target_ulong uaddr, int op, int val, target_ulong timeout, return -TARGET_ENOSYS; } } +#if defined(TARGET_NR_name_to_handle_at) && defined(CONFIG_OPEN_BY_HANDLE) +static abi_long do_name_to_handle_at(abi_long dirfd, abi_long pathname, + abi_long handle, abi_long mount_id, + abi_long flags) +{ + struct file_handle *target_fh; + struct file_handle *fh; + int mid = 0; + abi_long ret; + char *name; + unsigned int size, total_size; + + if (get_user_s32(size, handle)) { + return -TARGET_EFAULT; + } + + name = lock_user_string(pathname); + if (!name) { + return -TARGET_EFAULT; + } + + total_size = sizeof(struct file_handle) + size; + target_fh = lock_user(VERIFY_WRITE, handle, total_size, 0); + if (!target_fh) { + unlock_user(name, pathname, 0); + return -TARGET_EFAULT; + } + + fh = g_malloc0(total_size); + fh->handle_bytes = size; + + ret = get_errno(name_to_handle_at(dirfd, path(name), fh, &mid, flags)); + unlock_user(name, pathname, 0); + + /* man name_to_handle_at(2): + * Other than the use of the handle_bytes field, the caller should treat + * the file_handle structure as an opaque data type + */ + + memcpy(target_fh, fh, total_size); + target_fh->handle_bytes = tswap32(fh->handle_bytes); + target_fh->handle_type = tswap32(fh->handle_type); + g_free(fh); + unlock_user(target_fh, handle, total_size); + + if (put_user_s32(mid, mount_id)) { + return -TARGET_EFAULT; + } + + return ret; + +} +#endif + +#if defined(TARGET_NR_open_by_handle_at) && defined(CONFIG_OPEN_BY_HANDLE) +static abi_long do_open_by_handle_at(abi_long mount_fd, abi_long handle, + abi_long flags) +{ + struct file_handle *target_fh; + struct file_handle *fh; + unsigned int size, total_size; + abi_long ret; + + if (get_user_s32(size, handle)) { + return -TARGET_EFAULT; + } + + total_size = sizeof(struct file_handle) + size; + target_fh = lock_user(VERIFY_READ, handle, total_size, 1); + if (!target_fh) { + return -TARGET_EFAULT; + } + + fh = g_malloc0(total_size); + memcpy(fh, target_fh, total_size); + fh->handle_bytes = size; + fh->handle_type = tswap32(target_fh->handle_type); + + ret = get_errno(open_by_handle_at(mount_fd, fh, + target_to_host_bitmask(flags, fcntl_flags_tbl))); + + g_free(fh); + + unlock_user(target_fh, handle, total_size); + + return ret; +} +#endif /* Map host to target signal numbers for the wait family of syscalls. Assume all other status bits are the same. */ @@ -5655,6 +5743,16 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1, arg4)); unlock_user(p, arg2, 0); break; +#if defined(TARGET_NR_name_to_handle_at) && defined(CONFIG_OPEN_BY_HANDLE) + case TARGET_NR_name_to_handle_at: + ret = do_name_to_handle_at(arg1, arg2, arg3, arg4, arg5); + break; +#endif +#if defined(TARGET_NR_open_by_handle_at) && defined(CONFIG_OPEN_BY_HANDLE) + case TARGET_NR_open_by_handle_at: + ret = do_open_by_handle_at(arg1, arg2, arg3); + break; +#endif case TARGET_NR_close: ret = get_errno(close(arg1)); break;