From patchwork Mon Jul 31 22:42:45 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mike Tipton X-Patchwork-Id: 13335570 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 7F519C04A94 for ; Mon, 31 Jul 2023 22:43:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231133AbjGaWnQ (ORCPT ); Mon, 31 Jul 2023 18:43:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52010 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230356AbjGaWnP (ORCPT ); Mon, 31 Jul 2023 18:43:15 -0400 Received: from mx0b-0031df01.pphosted.com (mx0b-0031df01.pphosted.com [205.220.180.131]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8F5D419AC; Mon, 31 Jul 2023 15:43:14 -0700 (PDT) Received: from pps.filterd (m0279871.ppops.net [127.0.0.1]) by mx0a-0031df01.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 36VMUJgO025108; Mon, 31 Jul 2023 22:43:02 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=quicinc.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-type; s=qcppdkim1; bh=1SexRd3xlFPruhYV9RcOM8lB8ZoFnhXy4eJIe3MFfPY=; b=oFaCvuxt+BMzBY3tCODX4ya28AVGlb0ukM8sOqB9L1W6nL3SUggT2sRzpLylSBzh8zw7 bzyn+wNiY9U/MyxBzDo9POWW0jY5G8QwZU2xWQfQwax0NTrX6d/qgMjM6iJ0cC790ZTJ bHxVF+m6UyH7hdnnc3szut7wwOOPmzNi2HlqTHYoVVq/vV4gR+yeci9x06GdeLiMNk/1 EnnawfEXyKFA0uVpjUEc9pSuE6Kc5vbkpDOcMOjv2i5depjvYCLAnbrsJksQkP19hBpJ EDScd+dzWimpR5LjABsgv/CiPf55poIsiH1xyO9cXknqBuF1r5t7xpqCTIGRTizBmAt9 UQ== Received: from nalasppmta03.qualcomm.com (Global_NAT1.qualcomm.com [129.46.96.20]) by mx0a-0031df01.pphosted.com (PPS) with ESMTPS id 3s6d8gsguj-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 31 Jul 2023 22:43:02 +0000 Received: from nalasex01a.na.qualcomm.com (nalasex01a.na.qualcomm.com [10.47.209.196]) by NALASPPMTA03.qualcomm.com (8.17.1.5/8.17.1.5) with ESMTPS id 36VMh1oF030893 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 31 Jul 2023 22:43:01 GMT Received: from hu-mdtipton-lv.qualcomm.com (10.49.16.6) by nalasex01a.na.qualcomm.com (10.47.209.196) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1118.30; Mon, 31 Jul 2023 15:43:00 -0700 From: Mike Tipton To: , , , CC: , , , , , , Mike Tipton Subject: [PATCH v2 1/3] debugfs: Add write support to debugfs_create_str() Date: Mon, 31 Jul 2023 15:42:45 -0700 Message-ID: <20230731224247.10846-2-quic_mdtipton@quicinc.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20230731224247.10846-1-quic_mdtipton@quicinc.com> References: <20230731224247.10846-1-quic_mdtipton@quicinc.com> MIME-Version: 1.0 X-Originating-IP: [10.49.16.6] X-ClientProxiedBy: nalasex01a.na.qualcomm.com (10.47.209.196) To nalasex01a.na.qualcomm.com (10.47.209.196) X-QCInternal: smtphost X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=5800 signatures=585085 X-Proofpoint-ORIG-GUID: dlBiTlv5mbC4vvtxmDVArgBJFKBClj8_ X-Proofpoint-GUID: dlBiTlv5mbC4vvtxmDVArgBJFKBClj8_ X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.254,Aquarius:18.0.957,Hydra:6.0.591,FMLib:17.11.176.26 definitions=2023-07-31_15,2023-07-31_02,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxscore=0 lowpriorityscore=0 bulkscore=0 suspectscore=0 impostorscore=0 spamscore=0 adultscore=0 phishscore=0 priorityscore=1501 clxscore=1015 mlxlogscore=663 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2306200000 definitions=main-2307310206 Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org Currently, debugfs_create_str() only supports reading strings from debugfs. Add support for writing them as well. Based on original implementation by Peter Zijlstra [0]. Write support was present in the initial patch version, but dropped in v2 due to lack of users. We have a user now, so reintroduce it. [0] https://lore.kernel.org/all/YF3Hv5zXb%2F6lauzs@hirez.programming.kicks-ass.net/ Signed-off-by: Mike Tipton --- fs/debugfs/file.c | 48 +++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 46 insertions(+), 2 deletions(-) diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c index b7711888dd17..87b3753aa4b1 100644 --- a/fs/debugfs/file.c +++ b/fs/debugfs/file.c @@ -904,8 +904,52 @@ EXPORT_SYMBOL_GPL(debugfs_create_str); static ssize_t debugfs_write_file_str(struct file *file, const char __user *user_buf, size_t count, loff_t *ppos) { - /* This is really only for read-only strings */ - return -EINVAL; + struct dentry *dentry = F_DENTRY(file); + char *old, *new = NULL; + int pos = *ppos; + int r; + + r = debugfs_file_get(dentry); + if (unlikely(r)) + return r; + + old = *(char **)file->private_data; + + /* only allow strict concatenation */ + r = -EINVAL; + if (pos && pos != strlen(old)) + goto error; + + r = -E2BIG; + if (pos + count + 1 > PAGE_SIZE) + goto error; + + r = -ENOMEM; + new = kmalloc(pos + count + 1, GFP_KERNEL); + if (!new) + goto error; + + if (pos) + memcpy(new, old, pos); + + r = -EFAULT; + if (copy_from_user(new + pos, user_buf, count)) + goto error; + + new[pos + count] = '\0'; + strim(new); + + rcu_assign_pointer(*(char **)file->private_data, new); + synchronize_rcu(); + kfree(old); + + debugfs_file_put(dentry); + return count; + +error: + kfree(new); + debugfs_file_put(dentry); + return r; } static const struct file_operations fops_str = {