[PATCH v6 11/24] erofs: introduce xattr & posixacl support

Gao Xiang
2019-08-02T12:56:00Z

This implements xattr and posixacl functionalities.

1) Inline and shared xattrs are introduced for flexibility.

Specifically, if the same xattr is used for a large number of
inodes or the size of a xattr is so large that unsuitable to
inline, a shared xattr will be used instead in xattr meta.

2) Add .get_acl() to read the file's acl from its xattrs to
make POSIX ACL usable.

Here is the on-disk detail,
fullname: system.posix_acl_access
struct erofs_xattr_entry:
.e_name_len = 0
.e_name_index = EROFS_XATTR_INDEX_POSIX_ACL_ACCESS (2)

fullname: system.posix_acl_default
struct erofs_xattr_entry:
.e_name_len = 0
.e_name_index = EROFS_XATTR_INDEX_POSIX_ACL_DEFAULT (3)

Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
---
fs/erofs/Kconfig | 38 +++
fs/erofs/Makefile | 1 +
fs/erofs/inode.c | 14 +-
fs/erofs/internal.h | 16 +
fs/erofs/namei.c | 6 +-
fs/erofs/super.c | 77 ++++-
fs/erofs/xattr.c | 700 ++++++++++++++++++++++++++++++++++++++++++++
fs/erofs/xattr.h | 94 ++++++
8 files changed, 943 insertions(+), 3 deletions(-)
create mode 100644 fs/erofs/xattr.c
create mode 100644 fs/erofs/xattr.h

diff --git a/fs/erofs/Kconfig b/fs/erofs/Kconfig
index 98f05043448a..c5e7c5ae026e 100644
--- a/fs/erofs/Kconfig
+++ b/fs/erofs/Kconfig
@@ -34,3 +34,41 @@ config EROFS_FAULT_INJECTION
Test EROFS to inject faults such as ENOMEM, EIO, and so on.
If unsure, say N.

+config EROFS_FS_XATTR
+ bool "EROFS extended attributes"
+ depends on EROFS_FS
+ default y
+ help
+ Extended attributes are name:value pairs associated with inodes by
+ the kernel or by users (see the attr(5) manual page, or visit
+ <http://acl.bestbits.at/> for details).
+
+ If unsure, say N.
+
+config EROFS_FS_POSIX_ACL
+ bool "EROFS Access Control Lists"
+ depends on EROFS_FS_XATTR
+ select FS_POSIX_ACL
+ default y
+ help
+ Posix Access Control Lists (ACLs) support permissions for users and
+ groups beyond the owner/group/world scheme.
+
+ To learn more about Access Control Lists, visit the POSIX ACLs for
+ Linux website <http://acl.bestbits.at/>.
+
+ If you don't know what Access Control Lists are, say N.
+
+config EROFS_FS_SECURITY
+ bool "EROFS Security Labels"
+ depends on EROFS_FS_XATTR
+ default y
+ help
+ Security labels provide an access control facility to support Linux
+ Security Models (LSMs) accepted by AppArmor, SELinux, Smack and TOMOYO
+ Linux. This option enables an extended attribute handler for file
+ security labels in the erofs filesystem, so that it requires enabling
+ the extended attribute support in advance.
+
+ If you are not using a security module, say N.
+
diff --git a/fs/erofs/Makefile b/fs/erofs/Makefile
index c3f4e549ef90..190a73083f23 100644
--- a/fs/erofs/Makefile
+++ b/fs/erofs/Makefile
@@ -6,4 +6,5 @@ ccflags-y += -DEROFS_VERSION=\"$(EROFS_VERSION)\"

obj-$(CONFIG_EROFS_FS) += erofs.o
erofs-objs := super.o inode.o data.o namei.o dir.o
+erofs-$(CONFIG_EROFS_FS_XATTR) += xattr.o

diff --git a/fs/erofs/inode.c b/fs/erofs/inode.c
index 637bf6e4de44..aee53988aef5 100644
--- a/fs/erofs/inode.c
+++ b/fs/erofs/inode.c
@@ -6,7 +6,7 @@
* http://www.huawei.com/
* Created by Gao Xiang <gaoxiang25@huawei.com>
*/
-#include "internal.h"
+#include "xattr.h"

#include <trace/events/erofs.h>

@@ -300,15 +300,27 @@ int erofs_getattr(const struct path *path, struct kstat *stat,

const struct inode_operations erofs_generic_iops = {
.getattr = erofs_getattr,
+#ifdef CONFIG_EROFS_FS_XATTR
+ .listxattr = erofs_listxattr,
+#endif
+ .get_acl = erofs_get_acl,
};

const struct inode_operations erofs_symlink_iops = {
.get_link = page_get_link,
.getattr = erofs_getattr,
+#ifdef CONFIG_EROFS_FS_XATTR
+ .listxattr = erofs_listxattr,
+#endif
+ .get_acl = erofs_get_acl,
};

const struct inode_operations erofs_fast_symlink_iops = {
.get_link = simple_get_link,
.getattr = erofs_getattr,
+#ifdef CONFIG_EROFS_FS_XATTR
+ .listxattr = erofs_listxattr,
+#endif
+ .get_acl = erofs_get_acl,
};

diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index 2c94149d7218..004d5dbf2e7a 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -63,6 +63,9 @@ typedef u32 erofs_blk_t;
struct erofs_sb_info {
u32 blocks;
u32 meta_blkaddr;
+#ifdef CONFIG_EROFS_FS_XATTR
+ u32 xattr_blkaddr;
+#endif

/* inode slot unit size in bit shift */
unsigned char islotbits;
@@ -133,6 +136,8 @@ static inline void *erofs_kmalloc(struct erofs_sb_info *sbi,
#define EROFS_I_SB(inode) ((struct erofs_sb_info *)(inode)->i_sb->s_fs_info)

/* Mount flags set via mount options or defaults */
+#define EROFS_MOUNT_XATTR_USER 0x00000010
+#define EROFS_MOUNT_POSIX_ACL 0x00000020
#define EROFS_MOUNT_FAULT_INJECTION 0x00000040

#define clear_opt(sbi, option) ((sbi)->mount_opt &= ~EROFS_MOUNT_##option)
@@ -167,13 +172,24 @@ static inline erofs_off_t iloc(struct erofs_sb_info *sbi, erofs_nid_t nid)
return blknr_to_addr(sbi->meta_blkaddr) + (nid << sbi->islotbits);
}

+/* atomic flag definitions */
+#define EROFS_V_EA_INITED_BIT 0
+
+/* bitlock definitions (arranged in reverse order) */
+#define EROFS_V_BL_XATTR_BIT (BITS_PER_LONG - 1)
struct erofs_vnode {
erofs_nid_t nid;

+ /* atomic flags (including bitlocks) */
+ unsigned long flags;
+
unsigned char datamode;
unsigned char inode_isize;
unsigned short xattr_isize;

+ unsigned int xattr_shared_count;
+ unsigned int *xattr_shared_xattrs;
+
erofs_blk_t raw_blkaddr;
/* the corresponding vfs inode */
struct inode vfs_inode;
diff --git a/fs/erofs/namei.c b/fs/erofs/namei.c
index 73bf61637907..ccce53d46547 100644
--- a/fs/erofs/namei.c
+++ b/fs/erofs/namei.c
@@ -6,7 +6,7 @@
* http://www.huawei.com/
* Created by Gao Xiang <gaoxiang25@huawei.com>
*/
-#include "internal.h"
+#include "xattr.h"

#include <trace/events/erofs.h>

@@ -243,5 +243,9 @@ static struct dentry *erofs_lookup(struct inode *dir,
const struct inode_operations erofs_dir_iops = {
.lookup = erofs_lookup,
.getattr = erofs_getattr,
+#ifdef CONFIG_EROFS_FS_XATTR
+ .listxattr = erofs_listxattr,
+#endif
+ .get_acl = erofs_get_acl,
};

diff --git a/fs/erofs/super.c b/fs/erofs/super.c
index cd4bd6f48173..561ae6f7fe13 100644
--- a/fs/erofs/super.c
+++ b/fs/erofs/super.c
@@ -11,7 +11,7 @@
#include <linux/statfs.h>
#include <linux/parser.h>
#include <linux/seq_file.h>
-#include "internal.h"
+#include "xattr.h"

#define CREATE_TRACE_POINTS
#include <trace/events/erofs.h>
@@ -61,6 +61,8 @@ static void free_inode(struct inode *inode)
if (is_inode_fast_symlink(inode))
kfree(inode->i_link);

+ kfree(vi->xattr_shared_xattrs);
+
kmem_cache_free(erofs_inode_cachep, vi);
}

@@ -118,6 +120,9 @@ static int superblock_read(struct super_block *sb)

sbi->blocks = le32_to_cpu(layout->blocks);
sbi->meta_blkaddr = le32_to_cpu(layout->meta_blkaddr);
+#ifdef CONFIG_EROFS_FS_XATTR
+ sbi->xattr_blkaddr = le32_to_cpu(layout->xattr_blkaddr);
+#endif
sbi->islotbits = ffs(sizeof(struct erofs_inode_v1)) - 1;
sbi->root_nid = le16_to_cpu(layout->root_nid);
sbi->inos = le64_to_cpu(layout->inos);
@@ -195,14 +200,28 @@ static unsigned int erofs_get_fault_rate(struct erofs_sb_info *sbi)
/* set up default EROFS parameters */
static void default_options(struct erofs_sb_info *sbi)
{
+#ifdef CONFIG_EROFS_FS_XATTR
+ set_opt(sbi, XATTR_USER);
+#endif
+#ifdef CONFIG_EROFS_FS_POSIX_ACL
+ set_opt(sbi, POSIX_ACL);
+#endif
}

enum {
+ Opt_user_xattr,
+ Opt_nouser_xattr,
+ Opt_acl,
+ Opt_noacl,
Opt_fault_injection,
Opt_err
};

static match_table_t erofs_tokens = {
+ {Opt_user_xattr, "user_xattr"},
+ {Opt_nouser_xattr, "nouser_xattr"},
+ {Opt_acl, "acl"},
+ {Opt_noacl, "noacl"},
{Opt_fault_injection, "fault_injection=%u"},
{Opt_err, NULL}
};
@@ -226,6 +245,36 @@ static int parse_options(struct super_block *sb, char *options)
token = match_token(p, erofs_tokens, args);

switch (token) {
+#ifdef CONFIG_EROFS_FS_XATTR
+ case Opt_user_xattr:
+ set_opt(EROFS_SB(sb), XATTR_USER);
+ break;
+ case Opt_nouser_xattr:
+ clear_opt(EROFS_SB(sb), XATTR_USER);
+ break;
+#else
+ case Opt_user_xattr:
+ infoln("user_xattr options not supported");
+ break;
+ case Opt_nouser_xattr:
+ infoln("nouser_xattr options not supported");
+ break;
+#endif
+#ifdef CONFIG_EROFS_FS_POSIX_ACL
+ case Opt_acl:
+ set_opt(EROFS_SB(sb), POSIX_ACL);
+ break;
+ case Opt_noacl:
+ clear_opt(EROFS_SB(sb), POSIX_ACL);
+ break;
+#else
+ case Opt_acl:
+ infoln("acl options not supported");
+ break;
+ case Opt_noacl:
+ infoln("noacl options not supported");
+ break;
+#endif
case Opt_fault_injection:
err = erofs_build_fault_attr(EROFS_SB(sb), args);
if (err)
@@ -270,6 +319,10 @@ static int erofs_fill_super(struct super_block *sb, void *data, int silent)

sb->s_op = &erofs_sops;

+#ifdef CONFIG_EROFS_FS_XATTR
+ sb->s_xattr = erofs_xattr_handlers;
+#endif
+
/* set erofs default mount options */
default_options(sbi);

@@ -280,6 +333,11 @@ static int erofs_fill_super(struct super_block *sb, void *data, int silent)
if (!silent)
infoln("root inode @ nid %llu", ROOT_NID(sbi));

+ if (test_opt(sbi, POSIX_ACL))
+ sb->s_flags |= SB_POSIXACL;
+ else
+ sb->s_flags &= ~SB_POSIXACL;
+
/* get the root inode */
inode = erofs_iget(sb, ROOT_NID(sbi), true);
if (IS_ERR(inode))
@@ -393,6 +451,18 @@ static int erofs_show_options(struct seq_file *seq, struct dentry *root)
{
struct erofs_sb_info *sbi __maybe_unused = EROFS_SB(root->d_sb);

+#ifdef CONFIG_EROFS_FS_XATTR
+ if (test_opt(sbi, XATTR_USER))
+ seq_puts(seq, ",user_xattr");
+ else
+ seq_puts(seq, ",nouser_xattr");
+#endif
+#ifdef CONFIG_EROFS_FS_POSIX_ACL
+ if (test_opt(sbi, POSIX_ACL))
+ seq_puts(seq, ",acl");
+ else
+ seq_puts(seq, ",noacl");
+#endif
if (test_opt(sbi, FAULT_INJECTION))
seq_printf(seq, ",fault_injection=%u",
erofs_get_fault_rate(sbi));
@@ -411,6 +481,11 @@ static int erofs_remount(struct super_block *sb, int *flags, char *data)
if (err)
goto out;

+ if (test_opt(sbi, POSIX_ACL))
+ sb->s_flags |= SB_POSIXACL;
+ else
+ sb->s_flags &= ~SB_POSIXACL;
+
*flags |= SB_RDONLY;
return 0;
out:
diff --git a/fs/erofs/xattr.c b/fs/erofs/xattr.c
new file mode 100644
index 000000000000..148ceaf72790
--- /dev/null
+++ b/fs/erofs/xattr.c
@@ -0,0 +1,700 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * linux/fs/erofs/xattr.c
+ *
+ * Copyright (C) 2017-2018 HUAWEI, Inc.
+ * http://www.huawei.com/
+ * Created by Gao Xiang <gaoxiang25@huawei.com>
+ */
+#include <linux/security.h>
+#include "xattr.h"
+
+struct xattr_iter {
+ struct super_block *sb;
+ struct page *page;
+ void *kaddr;
+
+ erofs_blk_t blkaddr;
+ unsigned int ofs;
+};
+
+static inline void xattr_iter_end(struct xattr_iter *it, bool atomic)
+{
+ /* the only user of kunmap() is 'init_inode_xattrs' */
+ if (unlikely(!atomic))
+ kunmap(it->page);
+ else
+ kunmap_atomic(it->kaddr);
+
+ unlock_page(it->page);
+ put_page(it->page);
+}
+
+static inline void xattr_iter_end_final(struct xattr_iter *it)
+{
+ if (!it->page)
+ return;
+
+ xattr_iter_end(it, true);
+}
+
+static int init_inode_xattrs(struct inode *inode)
+{
+ struct erofs_vnode *const vi = EROFS_V(inode);
+ struct xattr_iter it;
+ unsigned int i;
+ struct erofs_xattr_ibody_header *ih;
+ struct super_block *sb;
+ struct erofs_sb_info *sbi;
+ bool atomic_map;
+ int ret = 0;
+
+ /* the most case is that xattrs of this inode are initialized. */
+ if (test_bit(EROFS_V_EA_INITED_BIT, &vi->flags))
+ return 0;
+
+ if (wait_on_bit_lock(&vi->flags, EROFS_V_BL_XATTR_BIT, TASK_KILLABLE))
+ return -ERESTARTSYS;
+
+ /* someone has initialized xattrs for us? */
+ if (test_bit(EROFS_V_EA_INITED_BIT, &vi->flags))
+ goto out_unlock;
+
+ /*
+ * bypass all xattr operations if ->xattr_isize is not greater than
+ * sizeof(struct erofs_xattr_ibody_header), in detail:
+ * 1) it is not enough to contain erofs_xattr_ibody_header then
+ * ->xattr_isize should be 0 (it means no xattr);
+ * 2) it is just to contain erofs_xattr_ibody_header, which is on-disk
+ * undefined right now (maybe use later with some new sb feature).
+ */
+ if (vi->xattr_isize == sizeof(struct erofs_xattr_ibody_header)) {
+ errln("xattr_isize %d of nid %llu is not supported yet",
+ vi->xattr_isize, vi->nid);
+ ret = -ENOTSUPP;
+ goto out_unlock;
+ } else if (vi->xattr_isize < sizeof(struct erofs_xattr_ibody_header)) {
+ if (unlikely(vi->xattr_isize)) {
+ DBG_BUGON(1);
+ ret = -EIO;
+ goto out_unlock; /* xattr ondisk layout error */
+ }
+ ret = -ENOATTR;
+ goto out_unlock;
+ }
+
+ sb = inode->i_sb;
+ sbi = EROFS_SB(sb);
+ it.blkaddr = erofs_blknr(iloc(sbi, vi->nid) + vi->inode_isize);
+ it.ofs = erofs_blkoff(iloc(sbi, vi->nid) + vi->inode_isize);
+
+ it.page = erofs_get_inline_page(inode, it.blkaddr);
+ if (IS_ERR(it.page)) {
+ ret = PTR_ERR(it.page);
+ goto out_unlock;
+ }
+
+ /* read in shared xattr array (non-atomic, see kmalloc below) */
+ it.kaddr = kmap(it.page);
+ atomic_map = false;
+
+ ih = (struct erofs_xattr_ibody_header *)(it.kaddr + it.ofs);
+
+ vi->xattr_shared_count = ih->h_shared_count;
+ vi->xattr_shared_xattrs = kmalloc_array(vi->xattr_shared_count,
+ sizeof(uint), GFP_KERNEL);
+ if (!vi->xattr_shared_xattrs) {
+ xattr_iter_end(&it, atomic_map);
+ ret = -ENOMEM;
+ goto out_unlock;
+ }
+
+ /* let's skip ibody header */
+ it.ofs += sizeof(struct erofs_xattr_ibody_header);
+
+ for (i = 0; i < vi->xattr_shared_count; ++i) {
+ if (unlikely(it.ofs >= EROFS_BLKSIZ)) {
+ /* cannot be unaligned */
+ BUG_ON(it.ofs != EROFS_BLKSIZ);
+ xattr_iter_end(&it, atomic_map);
+
+ it.page = erofs_get_meta_page(sb, ++it.blkaddr,
+ S_ISDIR(inode->i_mode));
+ if (IS_ERR(it.page)) {
+ kfree(vi->xattr_shared_xattrs);
+ vi->xattr_shared_xattrs = NULL;
+ ret = PTR_ERR(it.page);
+ goto out_unlock;
+ }
+
+ it.kaddr = kmap_atomic(it.page);
+ atomic_map = true;
+ it.ofs = 0;
+ }
+ vi->xattr_shared_xattrs[i] =
+ le32_to_cpu(*(__le32 *)(it.kaddr + it.ofs));
+ it.ofs += sizeof(__le32);
+ }
+ xattr_iter_end(&it, atomic_map);
+
+ set_bit(EROFS_V_EA_INITED_BIT, &vi->flags);
+
+out_unlock:
+ clear_and_wake_up_bit(EROFS_V_BL_XATTR_BIT, &vi->flags);
+ return ret;
+}
+
+/*
+ * the general idea for these return values is
+ * if 0 is returned, go on processing the current xattr;
+ * 1 (> 0) is returned, skip this round to process the next xattr;
+ * -err (< 0) is returned, an error (maybe ENOXATTR) occurred
+ * and need to be handled
+ */
+struct xattr_iter_handlers {
+ int (*entry)(struct xattr_iter *_it, struct erofs_xattr_entry *entry);
+ int (*name)(struct xattr_iter *_it, unsigned int processed, char *buf,
+ unsigned int len);
+ int (*alloc_buffer)(struct xattr_iter *_it, unsigned int value_sz);
+ void (*value)(struct xattr_iter *_it, unsigned int processed, char *buf,
+ unsigned int len);
+};
+
+static inline int xattr_iter_fixup(struct xattr_iter *it)
+{
+ if (it->ofs < EROFS_BLKSIZ)
+ return 0;
+
+ xattr_iter_end(it, true);
+
+ it->blkaddr += erofs_blknr(it->ofs);
+
+ it->page = erofs_get_meta_page(it->sb, it->blkaddr, false);
+ if (IS_ERR(it->page)) {
+ int err = PTR_ERR(it->page);
+
+ it->page = NULL;
+ return err;
+ }
+
+ it->kaddr = kmap_atomic(it->page);
+ it->ofs = erofs_blkoff(it->ofs);
+ return 0;
+}
+
+static int inline_xattr_iter_begin(struct xattr_iter *it,
+ struct inode *inode)
+{
+ struct erofs_vnode *const vi = EROFS_V(inode);
+ struct erofs_sb_info *const sbi = EROFS_SB(inode->i_sb);
+ unsigned int xattr_header_sz, inline_xattr_ofs;
+
+ xattr_header_sz = inlinexattr_header_size(inode);
+ if (unlikely(xattr_header_sz >= vi->xattr_isize)) {
+ BUG_ON(xattr_header_sz > vi->xattr_isize);
+ return -ENOATTR;
+ }
+
+ inline_xattr_ofs = vi->inode_isize + xattr_header_sz;
+
+ it->blkaddr = erofs_blknr(iloc(sbi, vi->nid) + inline_xattr_ofs);
+ it->ofs = erofs_blkoff(iloc(sbi, vi->nid) + inline_xattr_ofs);
+
+ it->page = erofs_get_inline_page(inode, it->blkaddr);
+ if (IS_ERR(it->page))
+ return PTR_ERR(it->page);
+
+ it->kaddr = kmap_atomic(it->page);
+ return vi->xattr_isize - xattr_header_sz;
+}
+
+/*
+ * Regardless of success or failure, `xattr_foreach' will end up with
+ * `ofs' pointing to the next xattr item rather than an arbitrary position.
+ */
+static int xattr_foreach(struct xattr_iter *it,
+ const struct xattr_iter_handlers *op,
+ unsigned int *tlimit)
+{
+ struct erofs_xattr_entry entry;
+ unsigned int value_sz, processed, slice;
+ int err;
+
+ /* 0. fixup blkaddr, ofs, ipage */
+ err = xattr_iter_fixup(it);
+ if (err)
+ return err;
+
+ /*
+ * 1. read xattr entry to the memory,
+ * since we do EROFS_XATTR_ALIGN
+ * therefore entry should be in the page
+ */
+ entry = *(struct erofs_xattr_entry *)(it->kaddr + it->ofs);
+ if (tlimit) {
+ unsigned int entry_sz = EROFS_XATTR_ENTRY_SIZE(&entry);
+
+ BUG_ON(*tlimit < entry_sz);
+ *tlimit -= entry_sz;
+ }
+
+ it->ofs += sizeof(struct erofs_xattr_entry);
+ value_sz = le16_to_cpu(entry.e_value_size);
+
+ /* handle entry */
+ err = op->entry(it, &entry);
+ if (err) {
+ it->ofs += entry.e_name_len + value_sz;
+ goto out;
+ }
+
+ /* 2. handle xattr name (ofs will finally be at the end of name) */
+ processed = 0;
+
+ while (processed < entry.e_name_len) {
+ if (it->ofs >= EROFS_BLKSIZ) {
+ BUG_ON(it->ofs > EROFS_BLKSIZ);
+
+ err = xattr_iter_fixup(it);
+ if (err)
+ goto out;
+ it->ofs = 0;
+ }
+
+ slice = min_t(unsigned int, PAGE_SIZE - it->ofs,
+ entry.e_name_len - processed);
+
+ /* handle name */
+ err = op->name(it, processed, it->kaddr + it->ofs, slice);
+ if (err) {
+ it->ofs += entry.e_name_len - processed + value_sz;
+ goto out;
+ }
+
+ it->ofs += slice;
+ processed += slice;
+ }
+
+ /* 3. handle xattr value */
+ processed = 0;
+
+ if (op->alloc_buffer) {
+ err = op->alloc_buffer(it, value_sz);
+ if (err) {
+ it->ofs += value_sz;
+ goto out;
+ }
+ }
+
+ while (processed < value_sz) {
+ if (it->ofs >= EROFS_BLKSIZ) {
+ BUG_ON(it->ofs > EROFS_BLKSIZ);
+
+ err = xattr_iter_fixup(it);
+ if (err)
+ goto out;
+ it->ofs = 0;
+ }
+
+ slice = min_t(unsigned int, PAGE_SIZE - it->ofs,
+ value_sz - processed);
+ op->value(it, processed, it->kaddr + it->ofs, slice);
+ it->ofs += slice;
+ processed += slice;
+ }
+
+out:
+ /* xattrs should be 4-byte aligned (on-disk constraint) */
+ it->ofs = EROFS_XATTR_ALIGN(it->ofs);
+ return err < 0 ? err : 0;
+}
+
+struct getxattr_iter {
+ struct xattr_iter it;
+
+ char *buffer;
+ int buffer_size, index;
+ struct qstr name;
+};
+
+static int xattr_entrymatch(struct xattr_iter *_it,
+ struct erofs_xattr_entry *entry)
+{
+ struct getxattr_iter *it = container_of(_it, struct getxattr_iter, it);
+
+ return (it->index != entry->e_name_index ||
+ it->name.len != entry->e_name_len) ? -ENOATTR : 0;
+}
+
+static int xattr_namematch(struct xattr_iter *_it,
+ unsigned int processed, char *buf, unsigned int len)
+{
+ struct getxattr_iter *it = container_of(_it, struct getxattr_iter, it);
+
+ return memcmp(buf, it->name.name + processed, len) ? -ENOATTR : 0;
+}
+
+static int xattr_checkbuffer(struct xattr_iter *_it,
+ unsigned int value_sz)
+{
+ struct getxattr_iter *it = container_of(_it, struct getxattr_iter, it);
+ int err = it->buffer_size < value_sz ? -ERANGE : 0;
+
+ it->buffer_size = value_sz;
+ return !it->buffer ? 1 : err;
+}
+
+static void xattr_copyvalue(struct xattr_iter *_it,
+ unsigned int processed,
+ char *buf, unsigned int len)
+{
+ struct getxattr_iter *it = container_of(_it, struct getxattr_iter, it);
+
+ memcpy(it->buffer + processed, buf, len);
+}
+
+static const struct xattr_iter_handlers find_xattr_handlers = {
+ .entry = xattr_entrymatch,
+ .name = xattr_namematch,
+ .alloc_buffer = xattr_checkbuffer,
+ .value = xattr_copyvalue
+};
+
+static int inline_getxattr(struct inode *inode, struct getxattr_iter *it)
+{
+ int ret;
+ unsigned int remaining;
+
+ ret = inline_xattr_iter_begin(&it->it, inode);
+ if (ret < 0)
+ return ret;
+
+ remaining = ret;
+ while (remaining) {
+ ret = xattr_foreach(&it->it, &find_xattr_handlers, &remaining);
+ if (ret != -ENOATTR)
+ break;
+ }
+ xattr_iter_end_final(&it->it);
+
+ return ret ? ret : it->buffer_size;
+}
+
+static int shared_getxattr(struct inode *inode, struct getxattr_iter *it)
+{
+ struct erofs_vnode *const vi = EROFS_V(inode);
+ struct super_block *const sb = inode->i_sb;
+ struct erofs_sb_info *const sbi = EROFS_SB(sb);
+ unsigned int i;
+ int ret = -ENOATTR;
+
+ for (i = 0; i < vi->xattr_shared_count; ++i) {
+ erofs_blk_t blkaddr =
+ xattrblock_addr(sbi, vi->xattr_shared_xattrs[i]);
+
+ it->it.ofs = xattrblock_offset(sbi, vi->xattr_shared_xattrs[i]);
+
+ if (!i || blkaddr != it->it.blkaddr) {
+ if (i)
+ xattr_iter_end(&it->it, true);
+
+ it->it.page = erofs_get_meta_page(sb, blkaddr, false);
+ if (IS_ERR(it->it.page))
+ return PTR_ERR(it->it.page);
+
+ it->it.kaddr = kmap_atomic(it->it.page);
+ it->it.blkaddr = blkaddr;
+ }
+
+ ret = xattr_foreach(&it->it, &find_xattr_handlers, NULL);
+ if (ret != -ENOATTR)
+ break;
+ }
+ if (vi->xattr_shared_count)
+ xattr_iter_end_final(&it->it);
+
+ return ret ? ret : it->buffer_size;
+}
+
+static bool erofs_xattr_user_list(struct dentry *dentry)
+{
+ return test_opt(EROFS_SB(dentry->d_sb), XATTR_USER);
+}
+
+static bool erofs_xattr_trusted_list(struct dentry *dentry)
+{
+ return capable(CAP_SYS_ADMIN);
+}
+
+int erofs_getxattr(struct inode *inode, int index,
+ const char *name,
+ void *buffer, size_t buffer_size)
+{
+ int ret;
+ struct getxattr_iter it;
+
+ if (unlikely(!name))
+ return -EINVAL;
+
+ ret = init_inode_xattrs(inode);
+ if (ret)
+ return ret;
+
+ it.index = index;
+
+ it.name.len = strlen(name);
+ if (it.name.len > EROFS_NAME_LEN)
+ return -ERANGE;
+ it.name.name = name;
+
+ it.buffer = buffer;
+ it.buffer_size = buffer_size;
+
+ it.it.sb = inode->i_sb;
+ ret = inline_getxattr(inode, &it);
+ if (ret == -ENOATTR)
+ ret = shared_getxattr(inode, &it);
+ return ret;
+}
+
+static int erofs_xattr_generic_get(const struct xattr_handler *handler,
+ struct dentry *unused, struct inode *inode,
+ const char *name, void *buffer, size_t size)
+{
+ struct erofs_sb_info *const sbi = EROFS_I_SB(inode);
+
+ switch (handler->flags) {
+ case EROFS_XATTR_INDEX_USER:
+ if (!test_opt(sbi, XATTR_USER))
+ return -EOPNOTSUPP;
+ break;
+ case EROFS_XATTR_INDEX_TRUSTED:
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+ break;
+ case EROFS_XATTR_INDEX_SECURITY:
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ return erofs_getxattr(inode, handler->flags, name, buffer, size);
+}
+
+const struct xattr_handler erofs_xattr_user_handler = {
+ .prefix = XATTR_USER_PREFIX,
+ .flags = EROFS_XATTR_INDEX_USER,
+ .list = erofs_xattr_user_list,
+ .get = erofs_xattr_generic_get,
+};
+
+const struct xattr_handler erofs_xattr_trusted_handler = {
+ .prefix = XATTR_TRUSTED_PREFIX,
+ .flags = EROFS_XATTR_INDEX_TRUSTED,
+ .list = erofs_xattr_trusted_list,
+ .get = erofs_xattr_generic_get,
+};
+
+#ifdef CONFIG_EROFS_FS_SECURITY
+const struct xattr_handler __maybe_unused erofs_xattr_security_handler = {
+ .prefix = XATTR_SECURITY_PREFIX,
+ .flags = EROFS_XATTR_INDEX_SECURITY,
+ .get = erofs_xattr_generic_get,
+};
+#endif
+
+const struct xattr_handler *erofs_xattr_handlers[] = {
+ &erofs_xattr_user_handler,
+#ifdef CONFIG_EROFS_FS_POSIX_ACL
+ &posix_acl_access_xattr_handler,
+ &posix_acl_default_xattr_handler,
+#endif
+ &erofs_xattr_trusted_handler,
+#ifdef CONFIG_EROFS_FS_SECURITY
+ &erofs_xattr_security_handler,
+#endif
+ NULL,
+};
+
+struct listxattr_iter {
+ struct xattr_iter it;
+
+ struct dentry *dentry;
+ char *buffer;
+ int buffer_size, buffer_ofs;
+};
+
+static int xattr_entrylist(struct xattr_iter *_it,
+ struct erofs_xattr_entry *entry)
+{
+ struct listxattr_iter *it =
+ container_of(_it, struct listxattr_iter, it);
+ unsigned int prefix_len;
+ const char *prefix;
+
+ const struct xattr_handler *h =
+ erofs_xattr_handler(entry->e_name_index);
+
+ if (!h || (h->list && !h->list(it->dentry)))
+ return 1;
+
+ prefix = xattr_prefix(h);
+ prefix_len = strlen(prefix);
+
+ if (!it->buffer) {
+ it->buffer_ofs += prefix_len + entry->e_name_len + 1;
+ return 1;
+ }
+
+ if (it->buffer_ofs + prefix_len
+ + entry->e_name_len + 1 > it->buffer_size)
+ return -ERANGE;
+
+ memcpy(it->buffer + it->buffer_ofs, prefix, prefix_len);
+ it->buffer_ofs += prefix_len;
+ return 0;
+}
+
+static int xattr_namelist(struct xattr_iter *_it,
+ unsigned int processed, char *buf, unsigned int len)
+{
+ struct listxattr_iter *it =
+ container_of(_it, struct listxattr_iter, it);
+
+ memcpy(it->buffer + it->buffer_ofs, buf, len);
+ it->buffer_ofs += len;
+ return 0;
+}
+
+static int xattr_skipvalue(struct xattr_iter *_it,
+ unsigned int value_sz)
+{
+ struct listxattr_iter *it =
+ container_of(_it, struct listxattr_iter, it);
+
+ it->buffer[it->buffer_ofs++] = '\0';
+ return 1;
+}
+
+static const struct xattr_iter_handlers list_xattr_handlers = {
+ .entry = xattr_entrylist,
+ .name = xattr_namelist,
+ .alloc_buffer = xattr_skipvalue,
+ .value = NULL
+};
+
+static int inline_listxattr(struct listxattr_iter *it)
+{
+ int ret;
+ unsigned int remaining;
+
+ ret = inline_xattr_iter_begin(&it->it, d_inode(it->dentry));
+ if (ret < 0)
+ return ret;
+
+ remaining = ret;
+ while (remaining) {
+ ret = xattr_foreach(&it->it, &list_xattr_handlers, &remaining);
+ if (ret)
+ break;
+ }
+ xattr_iter_end_final(&it->it);
+ return ret ? ret : it->buffer_ofs;
+}
+
+static int shared_listxattr(struct listxattr_iter *it)
+{
+ struct inode *const inode = d_inode(it->dentry);
+ struct erofs_vnode *const vi = EROFS_V(inode);
+ struct super_block *const sb = inode->i_sb;
+ struct erofs_sb_info *const sbi = EROFS_SB(sb);
+ unsigned int i;
+ int ret = 0;
+
+ for (i = 0; i < vi->xattr_shared_count; ++i) {
+ erofs_blk_t blkaddr =
+ xattrblock_addr(sbi, vi->xattr_shared_xattrs[i]);
+
+ it->it.ofs = xattrblock_offset(sbi, vi->xattr_shared_xattrs[i]);
+ if (!i || blkaddr != it->it.blkaddr) {
+ if (i)
+ xattr_iter_end(&it->it, true);
+
+ it->it.page = erofs_get_meta_page(sb, blkaddr, false);
+ if (IS_ERR(it->it.page))
+ return PTR_ERR(it->it.page);
+
+ it->it.kaddr = kmap_atomic(it->it.page);
+ it->it.blkaddr = blkaddr;
+ }
+
+ ret = xattr_foreach(&it->it, &list_xattr_handlers, NULL);
+ if (ret)
+ break;
+ }
+ if (vi->xattr_shared_count)
+ xattr_iter_end_final(&it->it);
+
+ return ret ? ret : it->buffer_ofs;
+}
+
+ssize_t erofs_listxattr(struct dentry *dentry,
+ char *buffer, size_t buffer_size)
+{
+ int ret;
+ struct listxattr_iter it;
+
+ ret = init_inode_xattrs(d_inode(dentry));
+ if (ret)
+ return ret;
+
+ it.dentry = dentry;
+ it.buffer = buffer;
+ it.buffer_size = buffer_size;
+ it.buffer_ofs = 0;
+
+ it.it.sb = dentry->d_sb;
+
+ ret = inline_listxattr(&it);
+ if (ret < 0 && ret != -ENOATTR)
+ return ret;
+ return shared_listxattr(&it);
+}
+
+#ifdef CONFIG_EROFS_FS_POSIX_ACL
+struct posix_acl *erofs_get_acl(struct inode *inode, int type)
+{
+ struct posix_acl *acl;
+ int prefix, rc;
+ char *value = NULL;
+
+ switch (type) {
+ case ACL_TYPE_ACCESS:
+ prefix = EROFS_XATTR_INDEX_POSIX_ACL_ACCESS;
+ break;
+ case ACL_TYPE_DEFAULT:
+ prefix = EROFS_XATTR_INDEX_POSIX_ACL_DEFAULT;
+ break;
+ default:
+ return ERR_PTR(-EINVAL);
+ }
+
+ rc = erofs_getxattr(inode, prefix, "", NULL, 0);
+ if (rc > 0) {
+ value = kmalloc(rc, GFP_KERNEL);
+ if (!value)
+ return ERR_PTR(-ENOMEM);
+ rc = erofs_getxattr(inode, prefix, "", value, rc);
+ }
+
+ if (rc == -ENOATTR)
+ acl = NULL;
+ else if (rc < 0)
+ acl = ERR_PTR(rc);
+ else
+ acl = posix_acl_from_xattr(&init_user_ns, value, rc);
+ kfree(value);
+ return acl;
+}
+#endif
+
diff --git a/fs/erofs/xattr.h b/fs/erofs/xattr.h
new file mode 100644
index 000000000000..d4213fff57e7
--- /dev/null
+++ b/fs/erofs/xattr.h
@@ -0,0 +1,94 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * linux/fs/erofs/xattr.h
+ *
+ * Copyright (C) 2017-2018 HUAWEI, Inc.
+ * http://www.huawei.com/
+ * Created by Gao Xiang <gaoxiang25@huawei.com>
+ */
+#ifndef __EROFS_XATTR_H
+#define __EROFS_XATTR_H
+
+#include "internal.h"
+#include <linux/posix_acl_xattr.h>
+#include <linux/xattr.h>
+
+/* Attribute not found */
+#define ENOATTR ENODATA
+
+static inline unsigned int inlinexattr_header_size(struct inode *inode)
+{
+ return sizeof(struct erofs_xattr_ibody_header)
+ + sizeof(u32) * EROFS_V(inode)->xattr_shared_count;
+}
+
+static inline erofs_blk_t xattrblock_addr(struct erofs_sb_info *sbi,
+ unsigned int xattr_id)
+{
+#ifdef CONFIG_EROFS_FS_XATTR
+ return sbi->xattr_blkaddr +
+ xattr_id * sizeof(__u32) / EROFS_BLKSIZ;
+#else
+ return 0;
+#endif
+}
+
+static inline unsigned int xattrblock_offset(struct erofs_sb_info *sbi,
+ unsigned int xattr_id)
+{
+ return (xattr_id * sizeof(__u32)) % EROFS_BLKSIZ;
+}
+
+#ifdef CONFIG_EROFS_FS_XATTR
+extern const struct xattr_handler erofs_xattr_user_handler;
+extern const struct xattr_handler erofs_xattr_trusted_handler;
+#ifdef CONFIG_EROFS_FS_SECURITY
+extern const struct xattr_handler erofs_xattr_security_handler;
+#endif
+
+static inline const struct xattr_handler *erofs_xattr_handler(unsigned int idx)
+{
+static const struct xattr_handler *xattr_handler_map[] = {
+ [EROFS_XATTR_INDEX_USER] = &erofs_xattr_user_handler,
+#ifdef CONFIG_EROFS_FS_POSIX_ACL
+ [EROFS_XATTR_INDEX_POSIX_ACL_ACCESS] = &posix_acl_access_xattr_handler,
+ [EROFS_XATTR_INDEX_POSIX_ACL_DEFAULT] =
+ &posix_acl_default_xattr_handler,
+#endif
+ [EROFS_XATTR_INDEX_TRUSTED] = &erofs_xattr_trusted_handler,
+#ifdef CONFIG_EROFS_FS_SECURITY
+ [EROFS_XATTR_INDEX_SECURITY] = &erofs_xattr_security_handler,
+#endif
+};
+
+ return idx && idx < ARRAY_SIZE(xattr_handler_map) ?
+ xattr_handler_map[idx] : NULL;
+}
+
+extern const struct xattr_handler *erofs_xattr_handlers[];
+
+int erofs_getxattr(struct inode *, int, const char *, void *, size_t);
+ssize_t erofs_listxattr(struct dentry *, char *, size_t);
+#else
+static inline int erofs_getxattr(struct inode *inode, int index,
+ const char *name, void *buffer,
+ size_t buffer_size)
+{
+ return -ENOTSUPP;
+}
+
+static inline ssize_t erofs_listxattr(struct dentry *dentry,
+ char *buffer, size_t buffer_size)
+{
+ return -ENOTSUPP;
+}
+#endif /* !CONFIG_EROFS_FS_XATTR */
+
+#ifdef CONFIG_EROFS_FS_POSIX_ACL
+struct posix_acl *erofs_get_acl(struct inode *inode, int type);
+#else
+#define erofs_get_acl (NULL)
+#endif
+
+#endif
+
--
2.17.1