linux-zen-desktop/fs/erofs/xattr.c

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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2017-2018 HUAWEI, Inc.
* https://www.huawei.com/
* Copyright (C) 2021-2022, Alibaba Cloud
*/
#include <linux/security.h>
#include "xattr.h"
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struct erofs_xattr_iter {
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struct super_block *sb;
struct erofs_buf buf;
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erofs_off_t pos;
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void *kaddr;
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char *buffer;
int buffer_size, buffer_ofs;
/* getxattr */
int index, infix_len;
struct qstr name;
/* listxattr */
struct dentry *dentry;
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};
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static int erofs_init_inode_xattrs(struct inode *inode)
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{
struct erofs_inode *const vi = EROFS_I(inode);
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struct erofs_xattr_iter it;
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unsigned int i;
struct erofs_xattr_ibody_header *ih;
struct super_block *sb = inode->i_sb;
int ret = 0;
/* the most case is that xattrs of this inode are initialized. */
if (test_bit(EROFS_I_EA_INITED_BIT, &vi->flags)) {
/*
* paired with smp_mb() at the end of the function to ensure
* fields will only be observed after the bit is set.
*/
smp_mb();
return 0;
}
if (wait_on_bit_lock(&vi->flags, EROFS_I_BL_XATTR_BIT, TASK_KILLABLE))
return -ERESTARTSYS;
/* someone has initialized xattrs for us? */
if (test_bit(EROFS_I_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)) {
erofs_err(sb,
"xattr_isize %d of nid %llu is not supported yet",
vi->xattr_isize, vi->nid);
ret = -EOPNOTSUPP;
goto out_unlock;
} else if (vi->xattr_isize < sizeof(struct erofs_xattr_ibody_header)) {
if (vi->xattr_isize) {
erofs_err(sb, "bogus xattr ibody @ nid %llu", vi->nid);
DBG_BUGON(1);
ret = -EFSCORRUPTED;
goto out_unlock; /* xattr ondisk layout error */
}
ret = -ENOATTR;
goto out_unlock;
}
it.buf = __EROFS_BUF_INITIALIZER;
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erofs_init_metabuf(&it.buf, sb);
it.pos = erofs_iloc(inode) + vi->inode_isize;
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/* read in shared xattr array (non-atomic, see kmalloc below) */
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it.kaddr = erofs_bread(&it.buf, erofs_blknr(sb, it.pos), EROFS_KMAP);
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if (IS_ERR(it.kaddr)) {
ret = PTR_ERR(it.kaddr);
goto out_unlock;
}
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ih = it.kaddr + erofs_blkoff(sb, it.pos);
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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) {
erofs_put_metabuf(&it.buf);
ret = -ENOMEM;
goto out_unlock;
}
/* let's skip ibody header */
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it.pos += sizeof(struct erofs_xattr_ibody_header);
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for (i = 0; i < vi->xattr_shared_count; ++i) {
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it.kaddr = erofs_bread(&it.buf, erofs_blknr(sb, it.pos),
EROFS_KMAP);
if (IS_ERR(it.kaddr)) {
kfree(vi->xattr_shared_xattrs);
vi->xattr_shared_xattrs = NULL;
ret = PTR_ERR(it.kaddr);
goto out_unlock;
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}
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vi->xattr_shared_xattrs[i] = le32_to_cpu(*(__le32 *)
(it.kaddr + erofs_blkoff(sb, it.pos)));
it.pos += sizeof(__le32);
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}
erofs_put_metabuf(&it.buf);
/* paired with smp_mb() at the beginning of the function. */
smp_mb();
set_bit(EROFS_I_EA_INITED_BIT, &vi->flags);
out_unlock:
clear_and_wake_up_bit(EROFS_I_BL_XATTR_BIT, &vi->flags);
return ret;
}
static bool erofs_xattr_user_list(struct dentry *dentry)
{
return test_opt(&EROFS_SB(dentry->d_sb)->opt, XATTR_USER);
}
static bool erofs_xattr_trusted_list(struct dentry *dentry)
{
return capable(CAP_SYS_ADMIN);
}
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)
{
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if (handler->flags == EROFS_XATTR_INDEX_USER &&
!test_opt(&EROFS_I_SB(inode)->opt, XATTR_USER))
return -EOPNOTSUPP;
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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,
&erofs_xattr_trusted_handler,
#ifdef CONFIG_EROFS_FS_SECURITY
&erofs_xattr_security_handler,
#endif
NULL,
};
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static int erofs_xattr_copy_to_buffer(struct erofs_xattr_iter *it,
unsigned int len)
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{
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unsigned int slice, processed;
struct super_block *sb = it->sb;
void *src;
for (processed = 0; processed < len; processed += slice) {
it->kaddr = erofs_bread(&it->buf, erofs_blknr(sb, it->pos),
EROFS_KMAP);
if (IS_ERR(it->kaddr))
return PTR_ERR(it->kaddr);
src = it->kaddr + erofs_blkoff(sb, it->pos);
slice = min_t(unsigned int, sb->s_blocksize -
erofs_blkoff(sb, it->pos), len - processed);
memcpy(it->buffer + it->buffer_ofs, src, slice);
it->buffer_ofs += slice;
it->pos += slice;
}
return 0;
}
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static int erofs_listxattr_foreach(struct erofs_xattr_iter *it)
{
struct erofs_xattr_entry entry;
unsigned int base_index, name_total, prefix_len, infix_len = 0;
const char *prefix, *infix = NULL;
int err;
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/* 1. handle xattr entry */
entry = *(struct erofs_xattr_entry *)
(it->kaddr + erofs_blkoff(it->sb, it->pos));
it->pos += sizeof(struct erofs_xattr_entry);
base_index = entry.e_name_index;
if (entry.e_name_index & EROFS_XATTR_LONG_PREFIX) {
struct erofs_sb_info *sbi = EROFS_SB(it->sb);
struct erofs_xattr_prefix_item *pf = sbi->xattr_prefixes +
(entry.e_name_index & EROFS_XATTR_LONG_PREFIX_MASK);
if (pf >= sbi->xattr_prefixes + sbi->xattr_prefix_count)
return 0;
infix = pf->prefix->infix;
infix_len = pf->infix_len;
base_index = pf->prefix->base_index;
}
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prefix = erofs_xattr_prefix(base_index, it->dentry);
if (!prefix)
return 0;
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prefix_len = strlen(prefix);
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name_total = prefix_len + infix_len + entry.e_name_len + 1;
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if (!it->buffer) {
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it->buffer_ofs += name_total;
return 0;
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}
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if (it->buffer_ofs + name_total > it->buffer_size)
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return -ERANGE;
memcpy(it->buffer + it->buffer_ofs, prefix, prefix_len);
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memcpy(it->buffer + it->buffer_ofs + prefix_len, infix, infix_len);
it->buffer_ofs += prefix_len + infix_len;
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/* 2. handle xattr name */
err = erofs_xattr_copy_to_buffer(it, entry.e_name_len);
if (err)
return err;
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it->buffer[it->buffer_ofs++] = '\0';
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return 0;
}
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static int erofs_getxattr_foreach(struct erofs_xattr_iter *it)
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{
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struct super_block *sb = it->sb;
struct erofs_xattr_entry entry;
unsigned int slice, processed, value_sz;
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/* 1. handle xattr entry */
entry = *(struct erofs_xattr_entry *)
(it->kaddr + erofs_blkoff(sb, it->pos));
it->pos += sizeof(struct erofs_xattr_entry);
value_sz = le16_to_cpu(entry.e_value_size);
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/* should also match the infix for long name prefixes */
if (entry.e_name_index & EROFS_XATTR_LONG_PREFIX) {
struct erofs_sb_info *sbi = EROFS_SB(sb);
struct erofs_xattr_prefix_item *pf = sbi->xattr_prefixes +
(entry.e_name_index & EROFS_XATTR_LONG_PREFIX_MASK);
if (pf >= sbi->xattr_prefixes + sbi->xattr_prefix_count)
return -ENOATTR;
if (it->index != pf->prefix->base_index ||
it->name.len != entry.e_name_len + pf->infix_len)
return -ENOATTR;
if (memcmp(it->name.name, pf->prefix->infix, pf->infix_len))
return -ENOATTR;
it->infix_len = pf->infix_len;
} else {
if (it->index != entry.e_name_index ||
it->name.len != entry.e_name_len)
return -ENOATTR;
it->infix_len = 0;
}
/* 2. handle xattr name */
for (processed = 0; processed < entry.e_name_len; processed += slice) {
it->kaddr = erofs_bread(&it->buf, erofs_blknr(sb, it->pos),
EROFS_KMAP);
if (IS_ERR(it->kaddr))
return PTR_ERR(it->kaddr);
slice = min_t(unsigned int,
sb->s_blocksize - erofs_blkoff(sb, it->pos),
entry.e_name_len - processed);
if (memcmp(it->name.name + it->infix_len + processed,
it->kaddr + erofs_blkoff(sb, it->pos), slice))
return -ENOATTR;
it->pos += slice;
}
/* 3. handle xattr value */
if (!it->buffer) {
it->buffer_ofs = value_sz;
return 0;
}
if (it->buffer_size < value_sz)
return -ERANGE;
return erofs_xattr_copy_to_buffer(it, value_sz);
}
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static int erofs_xattr_iter_inline(struct erofs_xattr_iter *it,
struct inode *inode, bool getxattr)
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{
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struct erofs_inode *const vi = EROFS_I(inode);
unsigned int xattr_header_sz, remaining, entry_sz;
erofs_off_t next_pos;
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int ret;
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xattr_header_sz = sizeof(struct erofs_xattr_ibody_header) +
sizeof(u32) * vi->xattr_shared_count;
if (xattr_header_sz >= vi->xattr_isize) {
DBG_BUGON(xattr_header_sz > vi->xattr_isize);
return -ENOATTR;
}
remaining = vi->xattr_isize - xattr_header_sz;
it->pos = erofs_iloc(inode) + vi->inode_isize + xattr_header_sz;
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while (remaining) {
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it->kaddr = erofs_bread(&it->buf, erofs_blknr(it->sb, it->pos),
EROFS_KMAP);
if (IS_ERR(it->kaddr))
return PTR_ERR(it->kaddr);
entry_sz = erofs_xattr_entry_size(it->kaddr +
erofs_blkoff(it->sb, it->pos));
/* xattr on-disk corruption: xattr entry beyond xattr_isize */
if (remaining < entry_sz) {
DBG_BUGON(1);
return -EFSCORRUPTED;
}
remaining -= entry_sz;
next_pos = it->pos + entry_sz;
if (getxattr)
ret = erofs_getxattr_foreach(it);
else
ret = erofs_listxattr_foreach(it);
if ((getxattr && ret != -ENOATTR) || (!getxattr && ret))
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break;
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it->pos = next_pos;
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}
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return ret;
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}
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static int erofs_xattr_iter_shared(struct erofs_xattr_iter *it,
struct inode *inode, bool getxattr)
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{
struct erofs_inode *const vi = EROFS_I(inode);
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struct super_block *const sb = it->sb;
struct erofs_sb_info *sbi = EROFS_SB(sb);
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unsigned int i;
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int ret = -ENOATTR;
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for (i = 0; i < vi->xattr_shared_count; ++i) {
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it->pos = erofs_pos(sb, sbi->xattr_blkaddr) +
vi->xattr_shared_xattrs[i] * sizeof(__le32);
it->kaddr = erofs_bread(&it->buf, erofs_blknr(sb, it->pos),
EROFS_KMAP);
if (IS_ERR(it->kaddr))
return PTR_ERR(it->kaddr);
if (getxattr)
ret = erofs_getxattr_foreach(it);
else
ret = erofs_listxattr_foreach(it);
if ((getxattr && ret != -ENOATTR) || (!getxattr && ret))
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break;
}
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return ret;
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}
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int erofs_getxattr(struct inode *inode, int index, const char *name,
void *buffer, size_t buffer_size)
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{
int ret;
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struct erofs_xattr_iter it;
if (!name)
return -EINVAL;
ret = erofs_init_inode_xattrs(inode);
if (ret)
return ret;
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it.index = index;
it.name = (struct qstr)QSTR_INIT(name, strlen(name));
if (it.name.len > EROFS_NAME_LEN)
return -ERANGE;
it.sb = inode->i_sb;
it.buf = __EROFS_BUF_INITIALIZER;
erofs_init_metabuf(&it.buf, it.sb);
it.buffer = buffer;
it.buffer_size = buffer_size;
it.buffer_ofs = 0;
ret = erofs_xattr_iter_inline(&it, inode, true);
if (ret == -ENOATTR)
ret = erofs_xattr_iter_shared(&it, inode, true);
erofs_put_metabuf(&it.buf);
return ret ? ret : it.buffer_ofs;
}
ssize_t erofs_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
{
int ret;
struct erofs_xattr_iter it;
struct inode *inode = d_inode(dentry);
ret = erofs_init_inode_xattrs(inode);
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if (ret == -ENOATTR)
return 0;
if (ret)
return ret;
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it.sb = dentry->d_sb;
it.buf = __EROFS_BUF_INITIALIZER;
erofs_init_metabuf(&it.buf, it.sb);
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it.dentry = dentry;
it.buffer = buffer;
it.buffer_size = buffer_size;
it.buffer_ofs = 0;
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ret = erofs_xattr_iter_inline(&it, inode, false);
if (!ret || ret == -ENOATTR)
ret = erofs_xattr_iter_shared(&it, inode, false);
if (ret == -ENOATTR)
ret = 0;
erofs_put_metabuf(&it.buf);
return ret ? ret : it.buffer_ofs;
}
void erofs_xattr_prefixes_cleanup(struct super_block *sb)
{
struct erofs_sb_info *sbi = EROFS_SB(sb);
int i;
if (sbi->xattr_prefixes) {
for (i = 0; i < sbi->xattr_prefix_count; i++)
kfree(sbi->xattr_prefixes[i].prefix);
kfree(sbi->xattr_prefixes);
sbi->xattr_prefixes = NULL;
}
}
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int erofs_xattr_prefixes_init(struct super_block *sb)
{
struct erofs_sb_info *sbi = EROFS_SB(sb);
struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
erofs_off_t pos = (erofs_off_t)sbi->xattr_prefix_start << 2;
struct erofs_xattr_prefix_item *pfs;
int ret = 0, i, len;
if (!sbi->xattr_prefix_count)
return 0;
pfs = kzalloc(sbi->xattr_prefix_count * sizeof(*pfs), GFP_KERNEL);
if (!pfs)
return -ENOMEM;
if (sbi->packed_inode)
buf.inode = sbi->packed_inode;
else
erofs_init_metabuf(&buf, sb);
for (i = 0; i < sbi->xattr_prefix_count; i++) {
void *ptr = erofs_read_metadata(sb, &buf, &pos, &len);
if (IS_ERR(ptr)) {
ret = PTR_ERR(ptr);
break;
} else if (len < sizeof(*pfs->prefix) ||
len > EROFS_NAME_LEN + sizeof(*pfs->prefix)) {
kfree(ptr);
ret = -EFSCORRUPTED;
break;
}
pfs[i].prefix = ptr;
pfs[i].infix_len = len - sizeof(struct erofs_xattr_long_prefix);
}
erofs_put_metabuf(&buf);
sbi->xattr_prefixes = pfs;
if (ret)
erofs_xattr_prefixes_cleanup(sb);
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return ret;
}
#ifdef CONFIG_EROFS_FS_POSIX_ACL
struct posix_acl *erofs_get_acl(struct inode *inode, int type, bool rcu)
{
struct posix_acl *acl;
int prefix, rc;
char *value = NULL;
if (rcu)
return ERR_PTR(-ECHILD);
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