From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5D022C54EED for ; Wed, 25 Jan 2023 22:08:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230257AbjAYWIH (ORCPT ); Wed, 25 Jan 2023 17:08:07 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57076 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230253AbjAYWIG (ORCPT ); Wed, 25 Jan 2023 17:08:06 -0500 Received: from mail-yb1-xb36.google.com (mail-yb1-xb36.google.com [IPv6:2607:f8b0:4864:20::b36]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 99DF4272E for ; Wed, 25 Jan 2023 14:08:00 -0800 (PST) Received: by mail-yb1-xb36.google.com with SMTP id 129so20886363ybb.0 for ; Wed, 25 Jan 2023 14:08:00 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=8cCX3Y5tMpHTPxdGP+eKd5H05mGoGhd8poBDVYoeLTo=; b=Kfk6HOfsvcxS2w6EkpDVfvvJgCCF/DvffgNZiCN2kvPi1KgC+riOaURGWiiHIBPvUM tinoQZVroy8ARazmEY+SSuc64b6tSLat9K6JYKix9+fj781rEz/rgOIHXtOpFuW1J68D c24RA6qzkEbHfi2faBuMKy3wnloeCgvN86U35SK+CCQz/2OyBgEUDxmbmYgDOXtBY0Io 1tXG+wo92Zfzjr6tja4/CWvhIJI9zPjiMSvncDQi5aZu/0REMikqGGySAXRXu8VIwJIY yVdUx5tucq3wqUsN2YKOqiTOOmiIMkpJCUKyG9a/fkjEUF9J4n0BBaPFz/BdGFSSkVRB KdtA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=8cCX3Y5tMpHTPxdGP+eKd5H05mGoGhd8poBDVYoeLTo=; b=KAyd56L5I1r+hyOavE+I8S3pPi9H9WXzuHWqfWmh6XfjomqWH+Pfob6FBlKPrHGbWq hi2fEz5J7eW7Jjem0BAU2iaTHlMfvzB4S2gADJEazjT0oIaNcTMPJLd6S+X2jqXkw9ZY Hx0XhQxHFXQkyzkymUSFKhot9OITVNVEXy4QKzV1Q8U6uk+HX1obVcGUmCUmfWAHwjns GRYaFOhBhqfApy3zdsu6wC+z3HAVDfGYkJ/UvmS9dYV+z8/DQq1gKLvtrsBpN3Y4DAIi GFDIWOFzS97EfdHzKPU0oQbuQybRfzNeK6yg5OE4alHcn15b4GBwGeu8cP5r/MYaWHCk KWSQ== X-Gm-Message-State: AFqh2kqP9/I5EvtCNpoJ5Kyw9FlcC7l3T8fuQiCiD+viJwtbkumQXAsU pBdwJJIwDGh6DDNcuapZg+4HKkWKpPVzEHdywnLTKA== X-Google-Smtp-Source: AMrXdXs7G0Oy1eOkRMD5hv9YO0RT324jdvsOMEaNF6TPQ8kzN5s9vSottpKNjr7WBsHmKfVNJPGh0dkRyT4f73X221U= X-Received: by 2002:a25:d505:0:b0:7bf:d201:60cb with SMTP id r5-20020a25d505000000b007bfd20160cbmr2763028ybe.365.1674684479589; Wed, 25 Jan 2023 14:07:59 -0800 (PST) MIME-Version: 1.0 References: <20230123191728.2928839-1-tjmercier@google.com> <20230123191728.2928839-4-tjmercier@google.com> In-Reply-To: From: "T.J. Mercier" Date: Wed, 25 Jan 2023 14:07:48 -0800 Message-ID: Subject: Re: [PATCH v2 3/4] binder: Add flags to relinquish ownership of fds To: Carlos Llamas Cc: Tejun Heo , Zefan Li , Johannes Weiner , Jonathan Corbet , Greg Kroah-Hartman , =?UTF-8?B?QXJ2ZSBIasO4bm5ldsOlZw==?= , Todd Kjos , Martijn Coenen , Joel Fernandes , Christian Brauner , Suren Baghdasaryan , daniel.vetter@ffwll.ch, android-mm@google.com, jstultz@google.com, jeffv@google.com, linux-security-module@vger.kernel.org, selinux@vger.kernel.org, cgroups@vger.kernel.org, Hridya Valsaraju , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On Wed, Jan 25, 2023 at 9:30 AM Carlos Llamas wrote: > > On Mon, Jan 23, 2023 at 07:17:25PM +0000, T.J. Mercier wrote: > > From: Hridya Valsaraju > > > > This patch introduces flag BINDER_FD_FLAG_XFER_CHARGE that a process > > sending an individual fd or fd array to another process over binder IPC > > can set to relinquish ownership of the fd(s) being sent for memory > > accounting purposes. If the flag is found to be set during the fd or fd > > array translation and the fd is for a DMA-BUF, the buffer is uncharged > > from the sender's cgroup and charged to the receiving process's cgroup > > instead. > > > > It is up to the sending process to ensure that it closes the fds > > regardless of whether the transfer failed or succeeded. > > > > Most graphics shared memory allocations in Android are done by the > > graphics allocator HAL process. On requests from clients, the HAL > > process allocates memory and sends the fds to the clients over binder > > IPC. The graphics allocator HAL will not retain any references to the > > buffers. When the HAL sets BINDER_FD_FLAG_XFER_CHARGE, binder will > > transfer the charge for the buffer from the allocator process cgroup to > > the client process cgroup. > > > > The pad [1] and pad_flags [2] fields of binder_fd_object and > > binder_fda_array_object come from alignment with flat_binder_object and > > have never been exposed for use from userspace. This new flags use > > follows the pattern set by binder_buffer_object. > > > > [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/include/uapi/linux/android/binder.h?id=feba3900cabb8e7c87368faa28e7a6936809ba22 > > [2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/include/uapi/linux/android/binder.h?id=5cdcf4c6a638591ec0e98c57404a19e7f9997567 > > > > Signed-off-by: Hridya Valsaraju > > Signed-off-by: T.J. Mercier > > --- > > Documentation/admin-guide/cgroup-v2.rst | 3 ++- > > drivers/android/binder.c | 25 +++++++++++++++++++++---- > > include/uapi/linux/android/binder.h | 19 +++++++++++++++---- > > 3 files changed, 38 insertions(+), 9 deletions(-) > > > > diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst > > index 538ae22bc514..d225295932c0 100644 > > --- a/Documentation/admin-guide/cgroup-v2.rst > > +++ b/Documentation/admin-guide/cgroup-v2.rst > > @@ -1457,7 +1457,8 @@ PAGE_SIZE multiple when read back. > > > > dmabuf (npn) > > Amount of memory used for exported DMA buffers allocated by the cgroup. > > - Stays with the allocating cgroup regardless of how the buffer is shared. > > + Stays with the allocating cgroup regardless of how the buffer is shared > > + unless explicitly transferred. > > > > workingset_refault_anon > > Number of refaults of previously evicted anonymous pages. > > diff --git a/drivers/android/binder.c b/drivers/android/binder.c > > index 880224ec6abb..5e707974793f 100644 > > --- a/drivers/android/binder.c > > +++ b/drivers/android/binder.c > > @@ -42,6 +42,7 @@ > > > > #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt > > > > +#include > > #include > > #include > > #include > > @@ -2237,7 +2238,7 @@ static int binder_translate_handle(struct flat_binder_object *fp, > > return ret; > > } > > > > -static int binder_translate_fd(u32 fd, binder_size_t fd_offset, > > +static int binder_translate_fd(u32 fd, binder_size_t fd_offset, __u32 flags, > > struct binder_transaction *t, > > struct binder_thread *thread, > > struct binder_transaction *in_reply_to) > > @@ -2275,6 +2276,20 @@ static int binder_translate_fd(u32 fd, binder_size_t fd_offset, > > goto err_security; > > } > > > > + if (IS_ENABLED(CONFIG_MEMCG) && (flags & BINDER_FD_FLAG_XFER_CHARGE)) { > > Do we need to test for MEMCG here? it seems this has been offloaded to > dma_buf_transfer_charge()? > Nope, that's a duplicate check now. Will remove. > > + ret = dma_buf_transfer_charge(file, target_proc->tsk); > > + if (unlikely(ret == -EBADF)) { > > + binder_user_error( > > + "%d:%d got transaction with XFER_CHARGE for non-DMA-BUF fd, %d\n", > > + proc->pid, thread->pid, fd); > > + goto err_dmabuf; > > + } else if (ret) { > > + pr_warn("%d:%d Unable to transfer DMA-BUF fd charge to %d\n", > > + proc->pid, thread->pid, target_proc->pid); > > + goto err_xfer; > > + } > > + } > > + > > /* > > * Add fixup record for this transaction. The allocation > > * of the fd in the target needs to be done from a > > @@ -2294,6 +2309,8 @@ static int binder_translate_fd(u32 fd, binder_size_t fd_offset, > > return ret; > > > > err_alloc: > > +err_xfer: > > +err_dmabuf: > > err_security: > > fput(file); > > err_fget: > > @@ -2604,7 +2621,7 @@ static int binder_translate_fd_array(struct list_head *pf_head, > > > > ret = copy_from_user(&fd, sender_ufda_base + sender_uoffset, sizeof(fd)); > > if (!ret) > > - ret = binder_translate_fd(fd, offset, t, thread, > > + ret = binder_translate_fd(fd, offset, fda->flags, t, thread, > > in_reply_to); > > if (ret) > > return ret > 0 ? -EINVAL : ret; > > @@ -3383,8 +3400,8 @@ static void binder_transaction(struct binder_proc *proc, > > struct binder_fd_object *fp = to_binder_fd_object(hdr); > > binder_size_t fd_offset = object_offset + > > (uintptr_t)&fp->fd - (uintptr_t)fp; > > - int ret = binder_translate_fd(fp->fd, fd_offset, t, > > - thread, in_reply_to); > > + int ret = binder_translate_fd(fp->fd, fd_offset, fp->flags, > > + t, thread, in_reply_to); > > > > fp->pad_binder = 0; > > if (ret < 0 || > > diff --git a/include/uapi/linux/android/binder.h b/include/uapi/linux/android/binder.h > > index e72e4de8f452..4b20dd1dccb1 100644 > > --- a/include/uapi/linux/android/binder.h > > +++ b/include/uapi/linux/android/binder.h > > @@ -91,14 +91,14 @@ struct flat_binder_object { > > /** > > * struct binder_fd_object - describes a filedescriptor to be fixed up. > > * @hdr: common header structure > > - * @pad_flags: padding to remain compatible with old userspace code > > + * @flags: One or more BINDER_FD_FLAG_* flags > > * @pad_binder: padding to remain compatible with old userspace code > > * @fd: file descriptor > > * @cookie: opaque data, used by user-space > > */ > > struct binder_fd_object { > > struct binder_object_header hdr; > > - __u32 pad_flags; > > + __u32 flags; > > union { > > binder_uintptr_t pad_binder; > > __u32 fd; > > @@ -107,6 +107,17 @@ struct binder_fd_object { > > binder_uintptr_t cookie; > > }; > > > > +enum { > > + /** > > + * @BINDER_FD_FLAG_XFER_CHARGE > > + * > > + * When set, the sender of a binder_fd_object wishes to relinquish ownership of the fd for > > + * memory accounting purposes. If the fd is for a DMA-BUF, the buffer is uncharged from the > > + * sender's cgroup and charged to the receiving process's cgroup instead. > > + */ > > + BINDER_FD_FLAG_XFER_CHARGE = 0x01, > > +}; > > + > > /* struct binder_buffer_object - object describing a userspace buffer > > * @hdr: common header structure > > * @flags: one or more BINDER_BUFFER_* flags > > @@ -141,7 +152,7 @@ enum { > > > > /* struct binder_fd_array_object - object describing an array of fds in a buffer > > * @hdr: common header structure > > - * @pad: padding to ensure correct alignment > > + * @flags: One or more BINDER_FD_FLAG_* flags > > * @num_fds: number of file descriptors in the buffer > > * @parent: index in offset array to buffer holding the fd array > > * @parent_offset: start offset of fd array in the buffer > > @@ -162,7 +173,7 @@ enum { > > */ > > struct binder_fd_array_object { > > struct binder_object_header hdr; > > - __u32 pad; > > + __u32 flags; > > binder_size_t num_fds; > > binder_size_t parent; > > binder_size_t parent_offset; > > -- > > 2.39.0.246.g2a6d74b583-goog > > > > Other than the previous question this looks good to me. Also, the error > from the test robot seems to indicate a missing stub for > dma_buf_transfer_charg() when !CONFIG_DMA_SHARED_BUFFER. However, this > is likely to be fixed outside of this patch. Feel free to add this tag > to the following round: > > Acked-by: Carlos Llamas > > Thanks, Got it, thanks!