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Mon, 2 Nov 2026 14:53:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793631221; bh=1qgL1NkV0P+SHvidYZZZVaI2a05IzcudOOYTRjrcE88=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=B3KPtGIP7tGmYNWXeX+H1i7tzVg1QuBKxBa4wYZl9yFfxSPwV/nb6la4JTArPoEWx ykM6GuLSG4T3qFKBXJYZCkJGC3vo8ibb5AaiCteOj34CmMoEHIQ9jN+136jYWHeTth F1T67wbusbZFJFAB68aEdSrwP7ELsjghDN+oafO9DTOUCxgQLH239365ae129l0kUM nRwyjSkChWEnrjfxrrWb5DyXYYNqiMK3X+fZLo7P3uKVMTCCcTjvGOV03/bfp2Z8WD FOtEMf9oTbUWnSFUeeH5hrLQ9dj/aKDWVT6F7HwyJbdDISBaRlBZGt5VGMwbWH7Jme DcXRqIaFfxaXw== From: Christian Brauner Date: Mon, 02 Nov 2026 15:48:52 +0100 Subject: [PATCH RFC 12/16] proc: copy in writes to the network namespace entries before pinning X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Owner: List-Post: List-Archive: , List-Subscribe: , , Precedence: list X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261102-work-procfs-core-v1-12-75df35e4f8b8@kernel.org> References: <20261102-work-procfs-core-v1-0-75df35e4f8b8@kernel.org> In-Reply-To: <20261102-work-procfs-core-v1-0-75df35e4f8b8@kernel.org> To: linux-fsdevel@vger.kernel.org Cc: Linus Torvalds , Jann Horn , Josef Bacik , Chris Mason , Jeff Layton , NeilBrown , Eric Dumazet , Thomas Gleixner , Al Viro , Jonathan Corbet , Christoph Hellwig , Greg Kroah-Hartman , Joel Granados , Kees Cook , Jan Kara , Jan Kara , linux-kernel@vger.kernel.org, linux-nfs@vger.kernel.org, linux-acpi@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-s390@vger.kernel.org, linux-scsi@vger.kernel.org, linux-um@lists.infradead.org, linux-wireless@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, netdev@vger.kernel.org, ntfs3@lists.linux.dev, platform-driver-x86@vger.kernel.org, coreteam@netfilter.org, kexec@lists.infradead.org, linux-pci@vger.kernel.org, linux-sound@vger.kernel.org, netfilter-devel@vger.kernel.org, dri-devel@lists.freedesktop.org, ibm-acpi-devel@lists.sourceforge.net, jfs-discussion@lists.sourceforge.net, linux-alpha@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-cifs@vger.kernel.org, linux-fbdev@vger.kernel.org, linux-hwmon@vger.kernel.org, linux-mm@kvack.org, linux-sh@vger.kernel.org, linux-usb@vger.kernel.org, samba-technical@lists.samba.org, sparclinux@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-doc@vger.kernel.org, linux-serial@vger.kernel.org, linux-atm-general@lists.sourceforge.net, Takashi Iwai , linux-input@vger.kernel.org, linux-raid@vger.kernel.org, linux-ext4@vger.kernel.org, linux-modules@vger.kernel.org, linux-debuggers@vger.kernel.org, "Christian Brauner (Amutable)" , Chuck Lever X-Mailer: b4 0.17-dev X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 proc_simple_write() already hands ->write() a kernel copy of what was written but makes that copy with the entry pinned. Let procfs make it before it pins the entry instead. That covers everything created with proc_create_net_data_write() and proc_create_net_single_write(), the afs files and the rxrpc stats. So a write to a proc_create_net_single() file without ->write() can fail with -EINVAL or -EFAULT now before proc_simple_write() gets to refuse it with -EACCES. Signed-off-by: Christian Brauner (Amutable) --- fs/proc/generic.c | 15 ++++----------- fs/proc/internal.h | 2 +- fs/proc/proc_net.c | 4 ++-- 3 files changed, 7 insertions(+), 14 deletions(-) diff --git a/fs/proc/generic.c b/fs/proc/generic.c index 7dc7df101286..83d273778a60 100644 --- a/fs/proc/generic.c +++ b/fs/proc/generic.c @@ -904,26 +904,19 @@ void proc_remove(struct proc_dir_entry *de) EXPORT_SYMBOL(proc_remove); /* - * Pull a user buffer into memory and pass it to the file's write handler if - * one is supplied. The ->write() method is permitted to modify the - * kernel-side buffer. + * Pass what was written to the file's write handler if one is supplied. The + * ->write() method is permitted to modify the buffer. */ -ssize_t proc_simple_write(struct file *f, const char __user *ubuf, size_t size, - loff_t *_pos) +ssize_t proc_simple_write(struct file *f, char *buf, size_t size, loff_t *_pos) { struct proc_dir_entry *pde = PDE(file_inode(f)); - char *buf; int ret; if (!pde->write) return -EACCES; - if (size == 0 || size > PAGE_SIZE - 1) + if (size == 0) return -EINVAL; - buf = memdup_user_nul(ubuf, size); - if (IS_ERR(buf)) - return PTR_ERR(buf); ret = pde->write(f, buf, size); - kfree(buf); return ret == 0 ? size : ret; } diff --git a/fs/proc/internal.h b/fs/proc/internal.h index 80b346a3299d..ed22c6dfb0bf 100644 --- a/fs/proc/internal.h +++ b/fs/proc/internal.h @@ -317,7 +317,7 @@ static inline bool is_empty_pde(const struct proc_dir_entry *pde) { return S_ISDIR(pde->mode) && !pde->proc_iops; } -extern ssize_t proc_simple_write(struct file *, const char __user *, size_t, loff_t *); +extern ssize_t proc_simple_write(struct file *, char *, size_t, loff_t *); /* * inode.c diff --git a/fs/proc/proc_net.c b/fs/proc/proc_net.c index fa485581d05e..cdeb2e025d2e 100644 --- a/fs/proc/proc_net.c +++ b/fs/proc/proc_net.c @@ -77,7 +77,7 @@ static int seq_release_net(struct inode *ino, struct file *f) static const struct proc_ops proc_net_seq_ops = { .proc_open = seq_open_net, - .proc_write = proc_simple_write, + .proc_write_buf = proc_simple_write, .proc_release = seq_release_net, }; @@ -186,7 +186,7 @@ static int single_release_net(struct inode *ino, struct file *f) static const struct proc_ops proc_net_single_ops = { .proc_open = single_open_net, - .proc_write = proc_simple_write, + .proc_write_buf = proc_simple_write, .proc_release = single_release_net, }; -- 2.53.0