From patchwork Wed Nov 29 21:50:26 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Seth Forshee (DigitalOcean)" X-Patchwork-Id: 13473552 X-Patchwork-Delegate: paul@paul-moore.com Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7C8A761FB4; Wed, 29 Nov 2023 21:50:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="ZCKANpzA" Received: by smtp.kernel.org (Postfix) with ESMTPS id E4CFEC433A9; Wed, 29 Nov 2023 21:50:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1701294657; bh=+rNu+aEJtyNDKr3Mz+sg00VpaKJj7LN1+EUYKCn22bc=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=ZCKANpzAjVN+iZhP0a6dpqp1xM6AJIp2C/3VFbXbPYlklUhPNfzkn7v5VbXxJQC6K tG9adpxF0Ec+kk2XBpQKlvQ8nOZM8jViq/EUplejF8Ou74+FGM8NfvmloHfXpcJWyK PEUQuZHqvIGBnfWoR5GC9oEFQT/S8Db+3lCwLHiWRA7O75lHulk+06FP0AAG6ps/W4 LFnbaTUFtdTWirRytgxK7jlaOPlsU4ZjJScsstI8DQzYfzilT/jO/Nbir0wlEHQiOg gWdY5zqroFCJ85q5h1BLBB+tC9Htz3qr+N/JSJBmoFz0UBeXD9nKePkkkoNIOEXgaW 7Fn8kko3KkrXA== Received: from aws-us-west-2-korg-lkml-1.web.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.lore.kernel.org (Postfix) with ESMTP id D4AABC10DC3; Wed, 29 Nov 2023 21:50:57 +0000 (UTC) From: "Seth Forshee (DigitalOcean)" Date: Wed, 29 Nov 2023 15:50:26 -0600 Subject: [PATCH 08/16] fs: add vfs_get_fscaps() Precedence: bulk X-Mailing-List: linux-security-module@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20231129-idmap-fscap-refactor-v1-8-da5a26058a5b@kernel.org> References: <20231129-idmap-fscap-refactor-v1-0-da5a26058a5b@kernel.org> In-Reply-To: <20231129-idmap-fscap-refactor-v1-0-da5a26058a5b@kernel.org> To: Christian Brauner , Serge Hallyn , Paul Moore , Eric Paris , James Morris , Alexander Viro , Miklos Szeredi , Amir Goldstein Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-security-module@vger.kernel.org, audit@vger.kernel.org, linux-unionfs@vger.kernel.org, "Seth Forshee (DigitalOcean)" X-Mailer: b4 0.12.4 X-Developer-Signature: v=1; a=openpgp-sha256; l=3647; i=sforshee@kernel.org; h=from:subject:message-id; bh=+rNu+aEJtyNDKr3Mz+sg00VpaKJj7LN1+EUYKCn22bc=; =?utf-8?q?b=3DowEBbQGS/pANAwAKAVMDma7l9DHJAcsmYgBlZ7I4/avu6/WjMpQysJRD4e086?= =?utf-8?q?dAG/Cwb8KohO3Og_fd3i1iGJATMEAAEKAB0WIQSQnt+rKAvnETy4Hc9TA5mu5fQxy?= =?utf-8?q?QUCZWeyOAAKCRBTA5mu5fQxyUF1B/_9oQr2DVGypJwRSipJa6KV9qSjXlv20xo0hN?= =?utf-8?q?hsSFvuH9Ach0ImZwoiRJyWGJTQ1qBcQPq7seTQQ+7B+_S2dK266E1ICJEoRmy+cIe?= =?utf-8?q?8P+BJme5M6yUAyFiSPqel1NPeKIbMFIGG6LST8fWtudf6UinqfhFZKyvd_qE1ALWh?= =?utf-8?q?6jQ12XE2xqlEPn0/tDpmo8eT7EU0F0z5LdbBiLGrQIQwMQpHnldwMwrCZkrjFnViq?= =?utf-8?q?2fZbAj_wzu2f79hmFumu4lFZ7Y4Gtb7CrOmipp/+6R4MsVmbtiaiiDpWIn3MrIlDO?= =?utf-8?q?0ivXbVWESxV66lWPdbWZ?= CcbdRRuAOliiqvt4XyKPp1qO4gEpFI X-Developer-Key: i=sforshee@kernel.org; a=openpgp; fpr=2ABCA7498D83E1D32D51D3B5AB4800A62DB9F73A X-Endpoint-Received: by B4 Relay for sforshee@kernel.org/default with auth_id=103 Provide a type-safe interface for retrieving filesystem capabilities and a generic implementation suitable for most filesystems. Also add an internal interface, __vfs_get_fscaps(), which skips security checks for later use from the capability code. Signed-off-by: Seth Forshee (DigitalOcean) --- fs/xattr.c | 66 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ include/linux/fs.h | 4 ++++ 2 files changed, 70 insertions(+) diff --git a/fs/xattr.c b/fs/xattr.c index 09d927603433..3abaf9bef0a5 100644 --- a/fs/xattr.c +++ b/fs/xattr.c @@ -181,6 +181,72 @@ xattr_supports_user_prefix(struct inode *inode) } EXPORT_SYMBOL(xattr_supports_user_prefix); +static int generic_get_fscaps(struct mnt_idmap *idmap, struct dentry *dentry, + struct vfs_caps *caps) +{ + struct inode *inode = d_inode(dentry); + struct vfs_ns_cap_data *nscaps = NULL; + int ret; + + ret = (int)vfs_getxattr_alloc(idmap, dentry, XATTR_NAME_CAPS, + (char **)&nscaps, 0, GFP_NOFS); + + if (ret >= 0) + ret = vfs_caps_from_xattr(idmap, i_user_ns(inode), caps, nscaps, ret); + + kfree(nscaps); + return ret; +} + +/** + * __vfs_get_fscaps - get filesystem capabilities without security checks + * @idmap: idmap of the mount the inode was found from + * @dentry: the dentry from which to get filesystem capabilities + * @caps: storage in which to return the filesystem capabilities + * + * This function gets the filesystem capabilities for the dentry and returns + * them in @caps. It does not perform security checks. + * + * Return: 0 on success, a negative errno on error. + */ +int __vfs_get_fscaps(struct mnt_idmap *idmap, struct dentry *dentry, + struct vfs_caps *caps) +{ + struct inode *inode = d_inode(dentry); + + if (inode->i_op->get_fscaps) + return inode->i_op->get_fscaps(idmap, dentry, caps); + return generic_get_fscaps(idmap, dentry, caps); +} + +/** + * vfs_get_fscaps - get filesystem capabilities + * @idmap: idmap of the mount the inode was found from + * @dentry: the dentry from which to get filesystem capabilities + * @caps: storage in which to return the filesystem capabilities + * + * This function gets the filesystem capabilities for the dentry and returns + * them in @caps. + * + * Return: 0 on success, a negative errno on error. + */ +int vfs_get_fscaps(struct mnt_idmap *idmap, struct dentry *dentry, + struct vfs_caps *caps) +{ + int error; + + /* + * The VFS has no restrictions on reading security.* xattrs, so + * xattr_permission() isn't needed. Only LSMs get a say. + */ + error = security_inode_getxattr(dentry, XATTR_NAME_CAPS); + if (error) + return error; + + return __vfs_get_fscaps(idmap, dentry, caps); +} +EXPORT_SYMBOL(vfs_get_fscaps); + int __vfs_setxattr(struct mnt_idmap *idmap, struct dentry *dentry, struct inode *inode, const char *name, const void *value, diff --git a/include/linux/fs.h b/include/linux/fs.h index a0a77f67b999..e25b39e4017a 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2055,6 +2055,10 @@ extern int vfs_dedupe_file_range(struct file *file, extern loff_t vfs_dedupe_file_range_one(struct file *src_file, loff_t src_pos, struct file *dst_file, loff_t dst_pos, loff_t len, unsigned int remap_flags); +extern int __vfs_get_fscaps(struct mnt_idmap *idmap, struct dentry *dentry, + struct vfs_caps *caps); +extern int vfs_get_fscaps(struct mnt_idmap *idmap, struct dentry *dentry, + struct vfs_caps *caps); enum freeze_holder { FREEZE_HOLDER_KERNEL = (1U << 0),