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Received-SPF: Pass (protection.outlook.com: domain of amd.com designates 165.204.84.17 as permitted sender) receiver=protection.outlook.com; client-ip=165.204.84.17; helo=SATLEXMB04.amd.com; pr=C Received: from SATLEXMB04.amd.com (165.204.84.17) by SA2PEPF00001504.mail.protection.outlook.com (10.167.242.36) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.20.7002.20 via Frontend Transport; Thu, 16 Nov 2023 22:48:05 +0000 Received: from titanite-d354host.amd.com (10.180.168.240) by SATLEXMB04.amd.com (10.181.40.145) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.32; Thu, 16 Nov 2023 16:48:03 -0600 From: Avadhut Naik To: , CC: , , , , , , , , , Subject: [PATCH v6 2/4] fs: debugfs: Add write functionality to debugfs blobs Date: Thu, 16 Nov 2023 16:47:23 -0600 Message-ID: <20231116224725.3695952-3-avadhut.naik@amd.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231116224725.3695952-1-avadhut.naik@amd.com> References: <20231116224725.3695952-1-avadhut.naik@amd.com> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Originating-IP: [10.180.168.240] X-ClientProxiedBy: SATLEXMB03.amd.com (10.181.40.144) To SATLEXMB04.amd.com (10.181.40.145) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SA2PEPF00001504:EE_|PH7PR12MB7162:EE_ X-MS-Office365-Filtering-Correlation-Id: 00f46e63-b25b-466c-a4fb-08dbe6f61888 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 16 Nov 2023 22:48:05.0383 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 00f46e63-b25b-466c-a4fb-08dbe6f61888 X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[SATLEXMB04.amd.com] X-MS-Exchange-CrossTenant-AuthSource: SA2PEPF00001504.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH7PR12MB7162 From: Avadhut Naik Currently, debugfs_create_blob() creates read-only debugfs binary blob files. In some cases, however, userspace tools need to write variable length data structures into predetermined memory addresses. An example is when injecting Vendor-defined error types through the einj module. In such cases, the functionality to write to these blob files in debugfs would be desired since the mapping aspect can be handled within the modules with userspace tools only needing to write into the blob files. Implement a write callback to enable writing to these blob files, created in debugfs, by owners only. Signed-off-by: Avadhut Naik Reviewed-by: Alexey Kardashevskiy Reviewed-by: Greg Kroah-Hartman Reviewed-by: Tony Luck --- fs/debugfs/file.c | 28 +++++++++++++++++++++++----- 1 file changed, 23 insertions(+), 5 deletions(-) diff --git a/fs/debugfs/file.c b/fs/debugfs/file.c index c45e8c2d62e1..00b834269aad 100644 --- a/fs/debugfs/file.c +++ b/fs/debugfs/file.c @@ -1008,17 +1008,35 @@ static ssize_t read_file_blob(struct file *file, char __user *user_buf, return r; } +static ssize_t write_file_blob(struct file *file, const char __user *user_buf, + size_t count, loff_t *ppos) +{ + struct debugfs_blob_wrapper *blob = file->private_data; + struct dentry *dentry = F_DENTRY(file); + ssize_t r; + + r = debugfs_file_get(dentry); + if (unlikely(r)) + return r; + r = simple_write_to_buffer(blob->data, blob->size, ppos, user_buf, + count); + + debugfs_file_put(dentry); + return r; +} + static const struct file_operations fops_blob = { .read = read_file_blob, + .write = write_file_blob, .open = simple_open, .llseek = default_llseek, }; /** - * debugfs_create_blob - create a debugfs file that is used to read a binary blob + * debugfs_create_blob - create a debugfs file that is used to read and write + * a binary blob * @name: a pointer to a string containing the name of the file to create. - * @mode: the read permission that the file should have (other permissions are - * masked out) + * @mode: the permission that the file should have * @parent: a pointer to the parent dentry for this file. This should be a * directory dentry if set. If this parameter is %NULL, then the * file will be created in the root of the debugfs filesystem. @@ -1027,7 +1045,7 @@ static const struct file_operations fops_blob = { * * This function creates a file in debugfs with the given name that exports * @blob->data as a binary blob. If the @mode variable is so set it can be - * read from. Writing is not supported. + * read from and written to. * * This function will return a pointer to a dentry if it succeeds. This * pointer must be passed to the debugfs_remove() function when the file is @@ -1042,7 +1060,7 @@ struct dentry *debugfs_create_blob(const char *name, umode_t mode, struct dentry *parent, struct debugfs_blob_wrapper *blob) { - return debugfs_create_file_unsafe(name, mode & 0444, parent, blob, &fops_blob); + return debugfs_create_file_unsafe(name, mode & 0644, parent, blob, &fops_blob); } EXPORT_SYMBOL_GPL(debugfs_create_blob);