1 files changed, 654 insertions, 0 deletions

diff --git a/fs/erofs/xattr.c b/fs/erofs/xattr.c
new file mode 100644
index 000000000..a2776abf3
--- /dev/null
+++ b/fs/erofs/xattr.c
@@ -0,0 +1,654 @@
+// 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"
+
+struct xattr_iter {
+	struct super_block *sb;
+	struct erofs_buf buf;
+	void *kaddr;
+
+	erofs_blk_t blkaddr;
+	unsigned int ofs;
+};
+
+static int init_inode_xattrs(struct inode *inode)
+{
+	struct erofs_inode *const vi = EROFS_I(inode);
+	struct 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;
+	it.blkaddr = erofs_blknr(erofs_iloc(inode) + vi->inode_isize);
+	it.ofs = erofs_blkoff(erofs_iloc(inode) + vi->inode_isize);
+
+	/* read in shared xattr array (non-atomic, see kmalloc below) */
+	it.kaddr = erofs_read_metabuf(&it.buf, sb, it.blkaddr, EROFS_KMAP);
+	if (IS_ERR(it.kaddr)) {
+		ret = PTR_ERR(it.kaddr);
+		goto out_unlock;
+	}
+
+	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) {
+		erofs_put_metabuf(&it.buf);
+		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 (it.ofs >= EROFS_BLKSIZ) {
+			/* cannot be unaligned */
+			DBG_BUGON(it.ofs != EROFS_BLKSIZ);
+
+			it.kaddr = erofs_read_metabuf(&it.buf, sb, ++it.blkaddr,
+						      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;
+			}
+			it.ofs = 0;
+		}
+		vi->xattr_shared_xattrs[i] =
+			le32_to_cpu(*(__le32 *)(it.kaddr + it.ofs));
+		it.ofs += 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;
+}
+
+/*
+ * 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;
+
+	it->blkaddr += erofs_blknr(it->ofs);
+	it->kaddr = erofs_read_metabuf(&it->buf, it->sb, it->blkaddr,
+				       EROFS_KMAP_ATOMIC);
+	if (IS_ERR(it->kaddr))
+		return PTR_ERR(it->kaddr);
+	it->ofs = erofs_blkoff(it->ofs);
+	return 0;
+}
+
+static int inline_xattr_iter_begin(struct xattr_iter *it,
+				   struct inode *inode)
+{
+	struct erofs_inode *const vi = EROFS_I(inode);
+	unsigned int xattr_header_sz, inline_xattr_ofs;
+
+	xattr_header_sz = inlinexattr_header_size(inode);
+	if (xattr_header_sz >= vi->xattr_isize) {
+		DBG_BUGON(xattr_header_sz > vi->xattr_isize);
+		return -ENOATTR;
+	}
+
+	inline_xattr_ofs = vi->inode_isize + xattr_header_sz;
+
+	it->blkaddr = erofs_blknr(erofs_iloc(inode) + inline_xattr_ofs);
+	it->ofs = erofs_blkoff(erofs_iloc(inode) + inline_xattr_ofs);
+	it->kaddr = erofs_read_metabuf(&it->buf, inode->i_sb, it->blkaddr,
+				       EROFS_KMAP_ATOMIC);
+	if (IS_ERR(it->kaddr))
+		return PTR_ERR(it->kaddr);
+	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);
+
+		/* xattr on-disk corruption: xattr entry beyond xattr_isize */
+		if (*tlimit < entry_sz) {
+			DBG_BUGON(1);
+			return -EFSCORRUPTED;
+		}
+		*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) {
+			DBG_BUGON(it->ofs > EROFS_BLKSIZ);
+
+			err = xattr_iter_fixup(it);
+			if (err)
+				goto out;
+			it->ofs = 0;
+		}
+
+		slice = min_t(unsigned int, EROFS_BLKSIZ - 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) {
+			DBG_BUGON(it->ofs > EROFS_BLKSIZ);
+
+			err = xattr_iter_fixup(it);
+			if (err)
+				goto out;
+			it->ofs = 0;
+		}
+
+		slice = min_t(unsigned int, EROFS_BLKSIZ - 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;
+	}
+	return ret ? ret : it->buffer_size;
+}
+
+static int shared_getxattr(struct inode *inode, struct getxattr_iter *it)
+{
+	struct erofs_inode *const vi = EROFS_I(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]);
+		it->it.kaddr = erofs_read_metabuf(&it->it.buf, sb, blkaddr,
+						  EROFS_KMAP_ATOMIC);
+		if (IS_ERR(it->it.kaddr))
+			return PTR_ERR(it->it.kaddr);
+		it->it.blkaddr = blkaddr;
+
+		ret = xattr_foreach(&it->it, &find_xattr_handlers, NULL);
+		if (ret != -ENOATTR)
+			break;
+	}
+	return ret ? ret : it->buffer_size;
+}
+
+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);
+}
+
+int erofs_getxattr(struct inode *inode, int index,
+		   const char *name,
+		   void *buffer, size_t buffer_size)
+{
+	int ret;
+	struct getxattr_iter it;
+
+	if (!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.it.buf = __EROFS_BUF_INITIALIZER;
+	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);
+	erofs_put_metabuf(&it.it.buf);
+	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->opt, XATTR_USER))
+			return -EOPNOTSUPP;
+		break;
+	case EROFS_XATTR_INDEX_TRUSTED:
+		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;
+	}
+	return ret ? ret : it->buffer_ofs;
+}
+
+static int shared_listxattr(struct listxattr_iter *it)
+{
+	struct inode *const inode = d_inode(it->dentry);
+	struct erofs_inode *const vi = EROFS_I(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]);
+		it->it.kaddr = erofs_read_metabuf(&it->it.buf, sb, blkaddr,
+						  EROFS_KMAP_ATOMIC);
+		if (IS_ERR(it->it.kaddr))
+			return PTR_ERR(it->it.kaddr);
+		it->it.blkaddr = blkaddr;
+
+		ret = xattr_foreach(&it->it, &list_xattr_handlers, NULL);
+		if (ret)
+			break;
+	}
+	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 == -ENOATTR)
+		return 0;
+	if (ret)
+		return ret;
+
+	it.it.buf = __EROFS_BUF_INITIALIZER;
+	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)
+		ret = shared_listxattr(&it);
+	erofs_put_metabuf(&it.it.buf);
+	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