linux/fs/bcachefs/xattr.c

// SPDX-License-Identifier: GPL-2.0

#include "bcachefs.h"
#include "acl.h"
#include "bkey_methods.h"
#include "btree_update.h"
#include "extents.h"
#include "fs.h"
#include "rebalance.h"
#include "str_hash.h"
#include "xattr.h"

#include <linux/dcache.h>
#include <linux/posix_acl_xattr.h>
#include <linux/xattr.h>

static const struct xattr_handler *bch2_xattr_type_to_handler(unsigned);

static u64 bch2_xattr_hash(const struct bch_hash_info *info,
			  const struct xattr_search_key *key)
{
	struct bch_str_hash_ctx ctx;

	bch2_str_hash_init(&ctx, info);
	bch2_str_hash_update(&ctx, info, &key->type, sizeof(key->type));
	bch2_str_hash_update(&ctx, info, key->name.name, key->name.len);

	return bch2_str_hash_end(&ctx, info);
}

static u64 xattr_hash_key(const struct bch_hash_info *info, const void *key)
{
	return bch2_xattr_hash(info, key);
}

static u64 xattr_hash_bkey(const struct bch_hash_info *info, struct bkey_s_c k)
{
	struct bkey_s_c_xattr x = bkey_s_c_to_xattr(k);

	return bch2_xattr_hash(info,
		 &X_SEARCH(x.v->x_type, x.v->x_name_and_value, x.v->x_name_len));
}

static bool xattr_cmp_key(struct bkey_s_c _l, const void *_r)
{
	struct bkey_s_c_xattr l = bkey_s_c_to_xattr(_l);
	const struct xattr_search_key *r = _r;

	return l.v->x_type != r->type ||
		l.v->x_name_len != r->name.len ||
		memcmp(l.v->x_name_and_value, r->name.name, r->name.len);
}

static bool xattr_cmp_bkey(struct bkey_s_c _l, struct bkey_s_c _r)
{
	struct bkey_s_c_xattr l = bkey_s_c_to_xattr(_l);
	struct bkey_s_c_xattr r = bkey_s_c_to_xattr(_r);

	return l.v->x_type != r.v->x_type ||
		l.v->x_name_len != r.v->x_name_len ||
		memcmp(l.v->x_name_and_value, r.v->x_name_and_value, r.v->x_name_len);
}

const struct bch_hash_desc bch2_xattr_hash_desc = {
	.btree_id	= BTREE_ID_xattrs,
	.key_type	= KEY_TYPE_xattr,
	.hash_key	= xattr_hash_key,
	.hash_bkey	= xattr_hash_bkey,
	.cmp_key	= xattr_cmp_key,
	.cmp_bkey	= xattr_cmp_bkey,
};

int bch2_xattr_validate(struct bch_fs *c, struct bkey_s_c k,
			struct bkey_validate_context from)
{
	struct bkey_s_c_xattr xattr = bkey_s_c_to_xattr(k);
	unsigned val_u64s = xattr_val_u64s(xattr.v->x_name_len,
					   le16_to_cpu(xattr.v->x_val_len));
	int ret = 0;

	bkey_fsck_err_on(bkey_val_u64s(k.k) < val_u64s,
			 c, xattr_val_size_too_small,
			 "value too small (%zu < %u)",
			 bkey_val_u64s(k.k), val_u64s);

	/* XXX why +4 ? */
	val_u64s = xattr_val_u64s(xattr.v->x_name_len,
				  le16_to_cpu(xattr.v->x_val_len) + 4);

	bkey_fsck_err_on(bkey_val_u64s(k.k) > val_u64s,
			 c, xattr_val_size_too_big,
			 "value too big (%zu > %u)",
			 bkey_val_u64s(k.k), val_u64s);

	bkey_fsck_err_on(!bch2_xattr_type_to_handler(xattr.v->x_type),
			 c, xattr_invalid_type,
			 "invalid type (%u)", xattr.v->x_type);

	bkey_fsck_err_on(memchr(xattr.v->x_name_and_value, '\0', xattr.v->x_name_len),
			 c, xattr_name_invalid_chars,
			 "xattr name has invalid characters");
fsck_err:
	return ret;
}

void bch2_xattr_to_text(struct printbuf *out, struct bch_fs *c,
			struct bkey_s_c k)
{
	const struct xattr_handler *handler;
	struct bkey_s_c_xattr xattr = bkey_s_c_to_xattr(k);

	handler = bch2_xattr_type_to_handler(xattr.v->x_type);
	if (handler && handler->prefix)
		prt_printf(out, "%s", handler->prefix);
	else if (handler)
		prt_printf(out, "(type %u)", xattr.v->x_type);
	else
		prt_printf(out, "(unknown type %u)", xattr.v->x_type);

	unsigned name_len = xattr.v->x_name_len;
	unsigned val_len  = le16_to_cpu(xattr.v->x_val_len);
	unsigned max_name_val_bytes = bkey_val_bytes(xattr.k) -
		offsetof(struct bch_xattr, x_name_and_value);

	val_len  = min_t(int, val_len, max_name_val_bytes - name_len);
	name_len = min(name_len, max_name_val_bytes);

	prt_printf(out, "%.*s:%.*s",
		   name_len, xattr.v->x_name_and_value,
		   val_len,  (char *) xattr_val(xattr.v));

	if (xattr.v->x_type == KEY_TYPE_XATTR_INDEX_POSIX_ACL_ACCESS ||
	    xattr.v->x_type == KEY_TYPE_XATTR_INDEX_POSIX_ACL_DEFAULT) {
		prt_char(out, ' ');
		bch2_acl_to_text(out, xattr_val(xattr.v),
				 le16_to_cpu(xattr.v->x_val_len));
	}
}

static int bch2_xattr_get_trans(struct btree_trans *trans, struct bch_inode_info *inode,
				const char *name, void *buffer, size_t size, int type)
{
	struct bch_hash_info hash = bch2_hash_info_init(trans->c, &inode->ei_inode);
	struct xattr_search_key search = X_SEARCH(type, name, strlen(name));
	struct btree_iter iter;
	struct bkey_s_c k = bch2_hash_lookup(trans, &iter, bch2_xattr_hash_desc, &hash,
					     inode_inum(inode), &search, 0);
	int ret = bkey_err(k);
	if (ret)
		return ret;

	struct bkey_s_c_xattr xattr = bkey_s_c_to_xattr(k);
	ret = le16_to_cpu(xattr.v->x_val_len);
	if (buffer) {
		if (ret > size)
			ret = -ERANGE;
		else
			memcpy(buffer, xattr_val(xattr.v), ret);
	}
	bch2_trans_iter_exit(trans, &iter);
	return ret;
}

int bch2_xattr_set(struct btree_trans *trans, subvol_inum inum,
		   struct bch_inode_unpacked *inode_u,
		   const struct bch_hash_info *hash_info,
		   const char *name, const void *value, size_t size,
		   int type, int flags)
{
	struct bch_fs *c = trans->c;
	struct btree_iter inode_iter = {};
	int ret;

	ret   = bch2_subvol_is_ro_trans(trans, inum.subvol) ?:
		bch2_inode_peek(trans, &inode_iter, inode_u, inum, BTREE_ITER_intent);
	if (ret)
		return ret;

	/*
	 * Besides the ctime update, extents, dirents and xattrs updates require
	 * that an inode update also happens - to ensure that if a key exists in
	 * one of those btrees with a given snapshot ID an inode is also present
	 */
	inode_u->bi_ctime = bch2_current_time(c);

	ret = bch2_inode_write(trans, &inode_iter, inode_u);
	bch2_trans_iter_exit(trans, &inode_iter);

	if (ret)
		return ret;

	if (value) {
		struct bkey_i_xattr *xattr;
		unsigned namelen = strlen(name);
		unsigned u64s = BKEY_U64s +
			xattr_val_u64s(namelen, size);

		if (u64s > U8_MAX)
			return -ERANGE;

		xattr = bch2_trans_kmalloc(trans, u64s * sizeof(u64));
		if (IS_ERR(xattr))
			return PTR_ERR(xattr);

		bkey_xattr_init(&xattr->k_i);
		xattr->k.u64s		= u64s;
		xattr->v.x_type		= type;
		xattr->v.x_name_len	= namelen;
		xattr->v.x_val_len	= cpu_to_le16(size);
		memcpy(xattr->v.x_name_and_value, name, namelen);
		memcpy(xattr_val(&xattr->v), value, size);

		ret = bch2_hash_set(trans, bch2_xattr_hash_desc, hash_info,
			      inum, &xattr->k_i,
			      (flags & XATTR_CREATE ? STR_HASH_must_create : 0)|
			      (flags & XATTR_REPLACE ? STR_HASH_must_replace : 0));
	} else {
		struct xattr_search_key search =
			X_SEARCH(type, name, strlen(name));

		ret = bch2_hash_delete(trans, bch2_xattr_hash_desc,
				       hash_info, inum, &search);
	}

	if (bch2_err_matches(ret, ENOENT))
		ret = flags & XATTR_REPLACE ? -ENODATA : 0;

	return ret;
}

struct xattr_buf {
	char		*buf;
	size_t		len;
	size_t		used;
};

static int __bch2_xattr_emit(const char *prefix,
			     const char *name, size_t name_len,
			     struct xattr_buf *buf)
{
	const size_t prefix_len = strlen(prefix);
	const size_t total_len = prefix_len + name_len + 1;

	if (buf->buf) {
		if (buf->used + total_len > buf->len)
			return -ERANGE;

		memcpy(buf->buf + buf->used, prefix, prefix_len);
		memcpy(buf->buf + buf->used + prefix_len,
		       name, name_len);
		buf->buf[buf->used + prefix_len + name_len] = '\0';
	}

	buf->used += total_len;
	return 0;
}

static inline const char *bch2_xattr_prefix(unsigned type, struct dentry *dentry)
{
	const struct xattr_handler *handler = bch2_xattr_type_to_handler(type);

	if (!xattr_handler_can_list(handler, dentry))
		return NULL;

	return xattr_prefix(handler);
}

static int bch2_xattr_emit(struct dentry *dentry,
			    const struct bch_xattr *xattr,
			    struct xattr_buf *buf)
{
	const char *prefix;

	prefix = bch2_xattr_prefix(xattr->x_type, dentry);
	if (!prefix)
		return 0;

	return __bch2_xattr_emit(prefix, xattr->x_name_and_value, xattr->x_name_len, buf);
}

static int bch2_xattr_list_bcachefs(struct bch_fs *c,
				    struct bch_inode_unpacked *inode,
				    struct xattr_buf *buf,
				    bool all)
{
	const char *prefix = all ? "bcachefs_effective." : "bcachefs.";
	unsigned id;
	int ret = 0;
	u64 v;

	for (id = 0; id < Inode_opt_nr; id++) {
		v = bch2_inode_opt_get(inode, id);
		if (!v)
			continue;

		if (!all &&
		    !(inode->bi_fields_set & (1 << id)))
			continue;

		ret = __bch2_xattr_emit(prefix, bch2_inode_opts[id],
					strlen(bch2_inode_opts[id]), buf);
		if (ret)
			break;
	}

	return ret;
}

ssize_t bch2_xattr_list(struct dentry *dentry, char *buffer, size_t buffer_size)
{
	struct bch_fs *c = dentry->d_sb->s_fs_info;
	struct bch_inode_info *inode = to_bch_ei(dentry->d_inode);
	struct xattr_buf buf = { .buf = buffer, .len = buffer_size };
	u64 offset = 0, inum = inode->ei_inode.bi_inum;

	int ret = bch2_trans_run(c,
		for_each_btree_key_in_subvolume_max(trans, iter, BTREE_ID_xattrs,
				   POS(inum, offset),
				   POS(inum, U64_MAX),
				   inode->ei_inum.subvol, 0, k, ({
			if (k.k->type != KEY_TYPE_xattr)
				continue;

			bch2_xattr_emit(dentry, bkey_s_c_to_xattr(k).v, &buf);
		}))) ?:
		bch2_xattr_list_bcachefs(c, &inode->ei_inode, &buf, false) ?:
		bch2_xattr_list_bcachefs(c, &inode->ei_inode, &buf, true);

	return ret ? bch2_err_class(ret) : buf.used;
}

static int bch2_xattr_get_handler(const struct xattr_handler *handler,
				  struct dentry *dentry, struct inode *vinode,
				  const char *name, void *buffer, size_t size)
{
	struct bch_inode_info *inode = to_bch_ei(vinode);
	struct bch_fs *c = inode->v.i_sb->s_fs_info;
	int ret = bch2_trans_do(c,
		bch2_xattr_get_trans(trans, inode, name, buffer, size, handler->flags));

	if (ret < 0 && bch2_err_matches(ret, ENOENT))
		ret = -ENODATA;

	return bch2_err_class(ret);
}

static int bch2_xattr_set_handler(const struct xattr_handler *handler,
				  struct mnt_idmap *idmap,
				  struct dentry *dentry, struct inode *vinode,
				  const char *name, const void *value,
				  size_t size, int flags)
{
	struct bch_inode_info *inode = to_bch_ei(vinode);
	struct bch_fs *c = inode->v.i_sb->s_fs_info;
	struct bch_hash_info hash = bch2_hash_info_init(c, &inode->ei_inode);
	struct bch_inode_unpacked inode_u;
	int ret;

	ret = bch2_trans_run(c,
		commit_do(trans, NULL, NULL, 0,
			bch2_xattr_set(trans, inode_inum(inode), &inode_u,
				       &hash, name, value, size,
				       handler->flags, flags)) ?:
		(bch2_inode_update_after_write(trans, inode, &inode_u, ATTR_CTIME), 0));

	return bch2_err_class(ret);
}

static const struct xattr_handler bch_xattr_user_handler = {
	.prefix	= XATTR_USER_PREFIX,
	.get	= bch2_xattr_get_handler,
	.set	= bch2_xattr_set_handler,
	.flags	= KEY_TYPE_XATTR_INDEX_USER,
};

static bool bch2_xattr_trusted_list(struct dentry *dentry)
{
	return capable(CAP_SYS_ADMIN);
}

static const struct xattr_handler bch_xattr_trusted_handler = {
	.prefix	= XATTR_TRUSTED_PREFIX,
	.list	= bch2_xattr_trusted_list,
	.get	= bch2_xattr_get_handler,
	.set	= bch2_xattr_set_handler,
	.flags	= KEY_TYPE_XATTR_INDEX_TRUSTED,
};

static const struct xattr_handler bch_xattr_security_handler = {
	.prefix	= XATTR_SECURITY_PREFIX,
	.get	= bch2_xattr_get_handler,
	.set	= bch2_xattr_set_handler,
	.flags	= KEY_TYPE_XATTR_INDEX_SECURITY,
};

#ifndef NO_BCACHEFS_FS

static int opt_to_inode_opt(int id)
{
	switch (id) {
#define x(name, ...)				\
	case Opt_##name: return Inode_opt_##name;
	BCH_INODE_OPTS()
#undef  x
	default:
		return -1;
	}
}

static int __bch2_xattr_bcachefs_get(const struct xattr_handler *handler,
				struct dentry *dentry, struct inode *vinode,
				const char *name, void *buffer, size_t size,
				bool all)
{
	struct bch_inode_info *inode = to_bch_ei(vinode);
	struct bch_fs *c = inode->v.i_sb->s_fs_info;
	struct bch_opts opts =
		bch2_inode_opts_to_opts(&inode->ei_inode);
	const struct bch_option *opt;
	int id, inode_opt_id;
	struct printbuf out = PRINTBUF;
	int ret;
	u64 v;

	id = bch2_opt_lookup(name);
	if (id < 0 || !bch2_opt_is_inode_opt(id))
		return -EINVAL;

	inode_opt_id = opt_to_inode_opt(id);
	if (inode_opt_id < 0)
		return -EINVAL;

	opt = bch2_opt_table + id;

	if (!bch2_opt_defined_by_id(&opts, id))
		return -ENODATA;

	if (!all &&
	    !(inode->ei_inode.bi_fields_set & (1 << inode_opt_id)))
		return -ENODATA;

	v = bch2_opt_get_by_id(&opts, id);
	bch2_opt_to_text(&out, c, c->disk_sb.sb, opt, v, 0);

	ret = out.pos;

	if (out.allocation_failure) {
		ret = -ENOMEM;
	} else if (buffer) {
		if (out.pos > size)
			ret = -ERANGE;
		else
			memcpy(buffer, out.buf, out.pos);
	}

	printbuf_exit(&out);
	return ret;
}

static int bch2_xattr_bcachefs_get(const struct xattr_handler *handler,
				   struct dentry *dentry, struct inode *vinode,
				   const char *name, void *buffer, size_t size)
{
	return __bch2_xattr_bcachefs_get(handler, dentry, vinode,
					 name, buffer, size, false);
}

struct inode_opt_set {
	int			id;
	u64			v;
	bool			defined;
};

static int inode_opt_set_fn(struct btree_trans *trans,
			    struct bch_inode_info *inode,
			    struct bch_inode_unpacked *bi,
			    void *p)
{
	struct inode_opt_set *s = p;

	if (s->id == Inode_opt_casefold) {
		int ret = bch2_inode_set_casefold(trans, inode_inum(inode), bi, s->v);
		if (ret)
			return ret;
	}

	if (s->defined)
		bi->bi_fields_set |= 1U << s->id;
	else
		bi->bi_fields_set &= ~(1U << s->id);

	bch2_inode_opt_set(bi, s->id, s->v);

	return 0;
}

static int bch2_xattr_bcachefs_set(const struct xattr_handler *handler,
				   struct mnt_idmap *idmap,
				   struct dentry *dentry, struct inode *vinode,
				   const char *name, const void *value,
				   size_t size, int flags)
{
	struct bch_inode_info *inode = to_bch_ei(vinode);
	struct bch_fs *c = inode->v.i_sb->s_fs_info;
	const struct bch_option *opt;
	char *buf;
	struct inode_opt_set s;
	int opt_id, inode_opt_id, ret;

	opt_id = bch2_opt_lookup(name);
	if (opt_id < 0)
		return -EINVAL;

	opt = bch2_opt_table + opt_id;

	inode_opt_id = opt_to_inode_opt(opt_id);
	if (inode_opt_id < 0)
		return -EINVAL;

	s.id = inode_opt_id;

	if (value) {
		u64 v = 0;

		buf = kmalloc(size + 1, GFP_KERNEL);
		if (!buf)
			return -ENOMEM;
		memcpy(buf, value, size);
		buf[size] = '\0';

		ret = bch2_opt_parse(c, opt, buf, &v, NULL);
		kfree(buf);

		if (ret < 0)
			goto err_class_exit;

		ret = bch2_opt_hook_pre_set(c, NULL, opt_id, v);
		if (ret < 0)
			goto err_class_exit;

		s.v = v + 1;
		s.defined = true;
	} else {
		/*
		 * Check if this option was set on the parent - if so, switched
		 * back to inheriting from the parent:
		 *
		 * rename() also has to deal with keeping inherited options up
		 * to date - see bch2_reinherit_attrs()
		 */
		spin_lock(&dentry->d_lock);
		if (!IS_ROOT(dentry)) {
			struct bch_inode_info *dir =
				to_bch_ei(d_inode(dentry->d_parent));

			s.v = bch2_inode_opt_get(&dir->ei_inode, inode_opt_id);
		} else {
			s.v = 0;
		}
		spin_unlock(&dentry->d_lock);

		s.defined = false;
	}

	mutex_lock(&inode->ei_update_lock);
	if (inode_opt_id == Inode_opt_project) {
		/*
		 * inode fields accessible via the xattr interface are stored
		 * with a +1 bias, so that 0 means unset:
		 */
		ret = bch2_set_projid(c, inode, s.v ? s.v - 1 : 0);
		if (ret)
			goto err;
	}

	ret = bch2_write_inode(c, inode, inode_opt_set_fn, &s, 0);
err:
	mutex_unlock(&inode->ei_update_lock);
err_class_exit:
	return bch2_err_class(ret);
}

static const struct xattr_handler bch_xattr_bcachefs_handler = {
	.prefix	= "bcachefs.",
	.get	= bch2_xattr_bcachefs_get,
	.set	= bch2_xattr_bcachefs_set,
};

static int bch2_xattr_bcachefs_get_effective(
				const struct xattr_handler *handler,
				struct dentry *dentry, struct inode *vinode,
				const char *name, void *buffer, size_t size)
{
	return __bch2_xattr_bcachefs_get(handler, dentry, vinode,
					 name, buffer, size, true);
}

/* Noop - xattrs in the bcachefs_effective namespace are inherited */
static int bch2_xattr_bcachefs_set_effective(const struct xattr_handler *handler,
				   struct mnt_idmap *idmap,
				   struct dentry *dentry, struct inode *vinode,
				   const char *name, const void *value,
				   size_t size, int flags)
{
	return 0;
}

static const struct xattr_handler bch_xattr_bcachefs_effective_handler = {
	.prefix	= "bcachefs_effective.",
	.get	= bch2_xattr_bcachefs_get_effective,
	.set	= bch2_xattr_bcachefs_set_effective,
};

#endif /* NO_BCACHEFS_FS */

const struct xattr_handler * const bch2_xattr_handlers[] = {
	&bch_xattr_user_handler,
	&bch_xattr_trusted_handler,
	&bch_xattr_security_handler,
#ifndef NO_BCACHEFS_FS
	&bch_xattr_bcachefs_handler,
	&bch_xattr_bcachefs_effective_handler,
#endif
	NULL
};

static const struct xattr_handler *bch_xattr_handler_map[] = {
	[KEY_TYPE_XATTR_INDEX_USER]			= &bch_xattr_user_handler,
	[KEY_TYPE_XATTR_INDEX_POSIX_ACL_ACCESS]	=
		&nop_posix_acl_access,
	[KEY_TYPE_XATTR_INDEX_POSIX_ACL_DEFAULT]	=
		&nop_posix_acl_default,
	[KEY_TYPE_XATTR_INDEX_TRUSTED]		= &bch_xattr_trusted_handler,
	[KEY_TYPE_XATTR_INDEX_SECURITY]		= &bch_xattr_security_handler,
};

static const struct xattr_handler *bch2_xattr_type_to_handler(unsigned type)
{
	return type < ARRAY_SIZE(bch_xattr_handler_map)
		? bch_xattr_handler_map[type]
		: NULL;
}