1 files changed, 560 insertions, 0 deletions

diff --git a/fs/erofs/xattr.c b/fs/erofs/xattr.c
new file mode 100644
index 000000000..09d341675
--- /dev/null
+++ b/fs/erofs/xattr.c
@@ -0,0 +1,560 @@
+// 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 <linux/xxhash.h>
+#include "xattr.h"
+
+struct erofs_xattr_iter {
+	struct super_block *sb;
+	struct erofs_buf buf;
+	erofs_off_t pos;
+	void *kaddr;
+
+	char *buffer;
+	int buffer_size, buffer_ofs;
+
+	/* getxattr */
+	int index, infix_len;
+	struct qstr name;
+
+	/* listxattr */
+	struct dentry *dentry;
+};
+
+static int erofs_init_inode_xattrs(struct inode *inode)
+{
+	struct erofs_inode *const vi = EROFS_I(inode);
+	struct erofs_xattr_iter it;
+	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;
+	erofs_init_metabuf(&it.buf, sb);
+	it.pos = erofs_iloc(inode) + vi->inode_isize;
+
+	/* read in shared xattr array (non-atomic, see kmalloc below) */
+	it.kaddr = erofs_bread(&it.buf, erofs_blknr(sb, it.pos), EROFS_KMAP);
+	if (IS_ERR(it.kaddr)) {
+		ret = PTR_ERR(it.kaddr);
+		goto out_unlock;
+	}
+
+	ih = it.kaddr + erofs_blkoff(sb, it.pos);
+	vi->xattr_name_filter = le32_to_cpu(ih->h_name_filter);
+	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 */
+	it.pos += sizeof(struct erofs_xattr_ibody_header);
+
+	for (i = 0; i < vi->xattr_shared_count; ++i) {
+		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;
+		}
+		vi->xattr_shared_xattrs[i] = le32_to_cpu(*(__le32 *)
+				(it.kaddr + erofs_blkoff(sb, it.pos)));
+		it.pos += sizeof(__le32);
+	}
+	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)
+{
+	if (handler->flags == EROFS_XATTR_INDEX_USER &&
+	    !test_opt(&EROFS_I_SB(inode)->opt, XATTR_USER))
+		return -EOPNOTSUPP;
+
+	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,
+};
+
+static int erofs_xattr_copy_to_buffer(struct erofs_xattr_iter *it,
+				      unsigned int len)
+{
+	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;
+}
+
+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;
+
+	/* 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;
+	}
+
+	prefix = erofs_xattr_prefix(base_index, it->dentry);
+	if (!prefix)
+		return 0;
+	prefix_len = strlen(prefix);
+	name_total = prefix_len + infix_len + entry.e_name_len + 1;
+
+	if (!it->buffer) {
+		it->buffer_ofs += name_total;
+		return 0;
+	}
+
+	if (it->buffer_ofs + name_total > it->buffer_size)
+		return -ERANGE;
+
+	memcpy(it->buffer + it->buffer_ofs, prefix, prefix_len);
+	memcpy(it->buffer + it->buffer_ofs + prefix_len, infix, infix_len);
+	it->buffer_ofs += prefix_len + infix_len;
+
+	/* 2. handle xattr name */
+	err = erofs_xattr_copy_to_buffer(it, entry.e_name_len);
+	if (err)
+		return err;
+
+	it->buffer[it->buffer_ofs++] = '\0';
+	return 0;
+}
+
+static int erofs_getxattr_foreach(struct erofs_xattr_iter *it)
+{
+	struct super_block *sb = it->sb;
+	struct erofs_xattr_entry entry;
+	unsigned int slice, processed, value_sz;
+
+	/* 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);
+
+	/* 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);
+}
+
+static int erofs_xattr_iter_inline(struct erofs_xattr_iter *it,
+				   struct inode *inode, bool getxattr)
+{
+	struct erofs_inode *const vi = EROFS_I(inode);
+	unsigned int xattr_header_sz, remaining, entry_sz;
+	erofs_off_t next_pos;
+	int ret;
+
+	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;
+
+	while (remaining) {
+		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))
+			break;
+
+		it->pos = next_pos;
+	}
+	return ret;
+}
+
+static int erofs_xattr_iter_shared(struct erofs_xattr_iter *it,
+				   struct inode *inode, bool getxattr)
+{
+	struct erofs_inode *const vi = EROFS_I(inode);
+	struct super_block *const sb = it->sb;
+	struct erofs_sb_info *sbi = EROFS_SB(sb);
+	unsigned int i;
+	int ret = -ENOATTR;
+
+	for (i = 0; i < vi->xattr_shared_count; ++i) {
+		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))
+			break;
+	}
+	return ret;
+}
+
+int erofs_getxattr(struct inode *inode, int index, const char *name,
+		   void *buffer, size_t buffer_size)
+{
+	int ret;
+	unsigned int hashbit;
+	struct erofs_xattr_iter it;
+	struct erofs_inode *vi = EROFS_I(inode);
+	struct erofs_sb_info *sbi = EROFS_SB(inode->i_sb);
+
+	if (!name)
+		return -EINVAL;
+
+	ret = erofs_init_inode_xattrs(inode);
+	if (ret)
+		return ret;
+
+	/* reserved flag is non-zero if there's any change of on-disk format */
+	if (erofs_sb_has_xattr_filter(sbi) && !sbi->xattr_filter_reserved) {
+		hashbit = xxh32(name, strlen(name),
+				EROFS_XATTR_FILTER_SEED + index);
+		hashbit &= EROFS_XATTR_FILTER_BITS - 1;
+		if (vi->xattr_name_filter & (1U << hashbit))
+			return -ENOATTR;
+	}
+
+	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);
+	if (ret == -ENOATTR)
+		return 0;
+	if (ret)
+		return ret;
+
+	it.sb = dentry->d_sb;
+	it.buf = __EROFS_BUF_INITIALIZER;
+	erofs_init_metabuf(&it.buf, it.sb);
+	it.dentry = dentry;
+	it.buffer = buffer;
+	it.buffer_size = buffer_size;
+	it.buffer_ofs = 0;
+
+	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;
+	}
+}
+
+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);
+	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