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Message-Id: <20200518060734.7159-1-janneke@gnu.org> Date: Mon, 18 May 2020 08:07:34 +0200 From: "Jan (janneke) Nieuwenhuizen" <janneke@....org> To: linux-ext4@...r.kernel.org, Theodore Ts'o <tytso@....edu>, Andreas Dilger <adilger.kernel@...ger.ca> Cc: Danny Milosavljevic <dannym@...atchpost.org>, Samuel Thibault <samuel.thibault@....org> Subject: [PATCH] ext4: support xattr gnu.* namespace for the Hurd The Hurd gained[0] support for moving the translator and author fields out of the inode and into the "gnu.*" xattr namespace. In anticipation of that, an xattr INDEX was reserved[1]. The Hurd has now been brought into compliance[2] with that. This patch adds support for reading and writing such attributes from Linux; you can now do something like dd if=/dev/zero of=file bs=1k count=1000 losetup /dev/loop0 file mke2fs -t ext2 -o hurd -O ext_attr /dev/loop0 mount -t ext2 /dev/loop0 /mnt mkdir -p /mnt/servers/socket touch /mnt/servers/socket/1 setfattr --name=gnu.translator --value='"/hurd/pflocal\0"' \ /mnt/servers/socket/1 getfattr --name=gnu.translator /mnt/servers/socket/1 # file: 1 gnu.translator="/hurd/pflocal" to setup a pipe translator, which is being used to create[3] a vm-image for the Hurd from GNU Guix. [0] https://summerofcode.withgoogle.com/projects/#5869799859027968 [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=3980bd3b406addb327d858aebd19e229ea340b9a [2] https://git.savannah.gnu.org/cgit/hurd/hurd.git/commit/?id=a04c7bf83172faa7cb080fbe3b6c04a8415ca645 [3] https://git.savannah.gnu.org/cgit/guix.git/log/?h=wip-hurd-vm --- fs/ext4/Kconfig | 11 ++++++++ fs/ext4/Makefile | 1 + fs/ext4/xattr.c | 6 ++++ fs/ext4/xattr.h | 1 + fs/ext4/xattr_hurd.c | 57 ++++++++++++++++++++++++++++++++++++++ include/uapi/linux/xattr.h | 4 +++ 6 files changed, 80 insertions(+) create mode 100644 fs/ext4/xattr_hurd.c diff --git a/fs/ext4/Kconfig b/fs/ext4/Kconfig index 2a592e38cdfe..e08f818eec4c 100644 --- a/fs/ext4/Kconfig +++ b/fs/ext4/Kconfig @@ -92,6 +92,17 @@ config EXT4_FS_SECURITY If you are not using a security module that requires using extended attributes for file security labels, say N. +config EXT4_FS_HURD + bool "Ext4 xattr gnu.* namespace support for the Hurd" + depends on EXT4_FS + help + Extended attributes are name:value pairs associated with inodes by + the kernel or by users (see the attr(5) manual page for details). + This option adds support for the gnu.* namespace ext4 file + systems for the Hurd. + + If you don't know what the GNU Hurd is, say N + config EXT4_DEBUG bool "Ext4 debugging support" depends on EXT4_FS diff --git a/fs/ext4/Makefile b/fs/ext4/Makefile index 4ccb3c9189d8..3c2c43167dbf 100644 --- a/fs/ext4/Makefile +++ b/fs/ext4/Makefile @@ -16,3 +16,4 @@ ext4-$(CONFIG_EXT4_FS_SECURITY) += xattr_security.o ext4-inode-test-objs += inode-test.o obj-$(CONFIG_EXT4_KUNIT_TESTS) += ext4-inode-test.o ext4-$(CONFIG_FS_VERITY) += verity.o +ext4-$(CONFIG_EXT4_FS_HURD) += xattr_hurd.o diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c index 21df43a25328..084361183a55 100644 --- a/fs/ext4/xattr.c +++ b/fs/ext4/xattr.c @@ -93,6 +93,9 @@ static const struct xattr_handler * const ext4_xattr_handler_map[] = { #ifdef CONFIG_EXT4_FS_SECURITY [EXT4_XATTR_INDEX_SECURITY] = &ext4_xattr_security_handler, #endif +#ifdef CONFIG_EXT4_FS_HURD + [EXT4_XATTR_INDEX_HURD] = &ext4_xattr_hurd_handler, +#endif }; const struct xattr_handler *ext4_xattr_handlers[] = { @@ -104,6 +107,9 @@ const struct xattr_handler *ext4_xattr_handlers[] = { #endif #ifdef CONFIG_EXT4_FS_SECURITY &ext4_xattr_security_handler, +#endif +#ifdef CONFIG_EXT4_FS_HURD + &ext4_xattr_hurd_handler, #endif NULL }; diff --git a/fs/ext4/xattr.h b/fs/ext4/xattr.h index ffe21ac77f78..730b91fa0dd7 100644 --- a/fs/ext4/xattr.h +++ b/fs/ext4/xattr.h @@ -124,6 +124,7 @@ struct ext4_xattr_inode_array { extern const struct xattr_handler ext4_xattr_user_handler; extern const struct xattr_handler ext4_xattr_trusted_handler; extern const struct xattr_handler ext4_xattr_security_handler; +extern const struct xattr_handler ext4_xattr_hurd_handler; #define EXT4_XATTR_NAME_ENCRYPTION_CONTEXT "c" diff --git a/fs/ext4/xattr_hurd.c b/fs/ext4/xattr_hurd.c new file mode 100644 index 000000000000..bc97cdcd5e65 --- /dev/null +++ b/fs/ext4/xattr_hurd.c @@ -0,0 +1,57 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * linux/fs/ext4/xattr_hurd.c + * Handler for extended gnu attributes for the Hurd. + * + * Copyright (C) 2001 by Andreas Gruenbacher, <a.gruenbacher@...puter.org> + * Copyright (C) 2020 by Jan (janneke) Nieuwenhuizen, <janneke@....org> + */ + +#include <linux/init.h> +#include <linux/string.h> +#include "ext4.h" +#include "xattr.h" + +static bool +ext4_xattr_hurd_list(struct dentry *dentry) +{ + return test_opt(dentry->d_sb, XATTR_USER) && + EXT4_SB(dentry->d_sb)->s_es->s_creator_os == + cpu_to_le32(EXT4_OS_HURD); +} + +static int +ext4_xattr_hurd_get(const struct xattr_handler *handler, + struct dentry *unused, struct inode *inode, + const char *name, void *buffer, size_t size) +{ + if (!test_opt(inode->i_sb, XATTR_USER) || + EXT4_SB(inode->i_sb)->s_es->s_creator_os != + cpu_to_le32(EXT4_OS_HURD)) + return -EOPNOTSUPP; + + return ext4_xattr_get(inode, EXT4_XATTR_INDEX_HURD, + name, buffer, size); +} + +static int +ext4_xattr_hurd_set(const struct xattr_handler *handler, + struct dentry *unused, struct inode *inode, + const char *name, const void *value, + size_t size, int flags) +{ + if (!test_opt(inode->i_sb, XATTR_USER) || + EXT4_SB(inode->i_sb)->s_es->s_creator_os != + cpu_to_le32(EXT4_OS_HURD)) + return -EOPNOTSUPP; + + return ext4_xattr_set(inode, EXT4_XATTR_INDEX_HURD, + name, value, size, flags); +} + +const struct xattr_handler ext4_xattr_hurd_handler = { + .prefix = XATTR_HURD_PREFIX, + .list = ext4_xattr_hurd_list, + .get = ext4_xattr_hurd_get, + .set = ext4_xattr_hurd_set, +}; diff --git a/include/uapi/linux/xattr.h b/include/uapi/linux/xattr.h index c1395b5bd432..9463db2dfa9d 100644 --- a/include/uapi/linux/xattr.h +++ b/include/uapi/linux/xattr.h @@ -7,6 +7,7 @@ Copyright (C) 2001 by Andreas Gruenbacher <a.gruenbacher@...puter.org> Copyright (c) 2001-2002 Silicon Graphics, Inc. All Rights Reserved. Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@...hat.com> + Copyright (c) 2020 Jan (janneke) Nieuwenhuizen <janneke@....org> */ #include <linux/libc-compat.h> @@ -31,6 +32,9 @@ #define XATTR_BTRFS_PREFIX "btrfs." #define XATTR_BTRFS_PREFIX_LEN (sizeof(XATTR_BTRFS_PREFIX) - 1) +#define XATTR_HURD_PREFIX "gnu." +#define XATTR_HURD_PREFIX_LEN (sizeof(XATTR_HURD_PREFIX) - 1) + #define XATTR_SECURITY_PREFIX "security." #define XATTR_SECURITY_PREFIX_LEN (sizeof(XATTR_SECURITY_PREFIX) - 1) -- 2.26.2
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