// SPDX-License-Identifier: GPL-2.0

#include "bcachefs.h"

#include "acl.h"
#include "xattr.h"

#include <linux/posix_acl.h>

static const char * const acl_types[] = {
	[ACL_USER_OBJ]	= "user_obj",
	[ACL_USER]	= "user",
	[ACL_GROUP_OBJ]	= "group_obj",
	[ACL_GROUP]	= "group",
	[ACL_MASK]	= "mask",
	[ACL_OTHER]	= "other",
	NULL,
};

__cold void bch2_acl_to_text(struct printbuf *out, const void *value, size_t size)
{
	const void *p, *end = value + size;

	if (!value ||
	    size < sizeof(bch_acl_header) ||
	    ((bch_acl_header *)value)->a_version != cpu_to_le32(BCH_ACL_VERSION))
		return;

	p = value + sizeof(bch_acl_header);
	while (p < end) {
		const bch_acl_entry *in = p;
		unsigned tag = le16_to_cpu(in->e_tag);

		prt_str(out, acl_types[tag]);

		switch (tag) {
		case ACL_USER_OBJ:
		case ACL_GROUP_OBJ:
		case ACL_MASK:
		case ACL_OTHER:
			p += sizeof(bch_acl_entry_short);
			break;
		case ACL_USER:
			prt_printf(out, " uid %u", le32_to_cpu(in->e_id));
			p += sizeof(bch_acl_entry);
			break;
		case ACL_GROUP:
			prt_printf(out, " gid %u", le32_to_cpu(in->e_id));
			p += sizeof(bch_acl_entry);
			break;
		}

		prt_printf(out, " %o", le16_to_cpu(in->e_perm));

		if (p != end)
			prt_char(out, ' ');
	}
}

#ifndef NO_BCACHEFS_FS

#include "vfs/fs.h"

#include <linux/fs.h>
#include <linux/posix_acl_xattr.h>
#include <linux/sched.h>
#include <linux/slab.h>

static inline size_t bch2_acl_size(unsigned nr_short, unsigned nr_long)
{
	return sizeof(bch_acl_header) +
		sizeof(bch_acl_entry_short) * nr_short +
		sizeof(bch_acl_entry) * nr_long;
}

static inline int acl_to_xattr_type(int type)
{
	switch (type) {
	case ACL_TYPE_ACCESS:
		return KEY_TYPE_XATTR_INDEX_POSIX_ACL_ACCESS;
	case ACL_TYPE_DEFAULT:
		return KEY_TYPE_XATTR_INDEX_POSIX_ACL_DEFAULT;
	default:
		BUG();
	}
}

static struct posix_acl *acl_entry_invalid(struct bkey_s_c_xattr xattr)
{
	pr_err("invalid acl entry");
	return ERR_PTR(-EINVAL);
}

/*
 * Convert from filesystem to in-memory representation.
 */
static struct posix_acl *bch2_acl_from_disk(struct btree_trans *trans,
					    struct bkey_s_c_xattr xattr)
{
	const void *value = xattr_val(xattr.v);
	size_t size = le16_to_cpu(xattr.v->x_val_len);
	const void *p, *end = value + size;
	struct posix_acl *acl;
	struct posix_acl_entry *out;
	unsigned count = 0;
	int ret;

	if (!value)
		return NULL;
	if (size < sizeof(bch_acl_header))
		return acl_entry_invalid(xattr);
	if (((bch_acl_header *)value)->a_version !=
	    cpu_to_le32(BCH_ACL_VERSION))
		return acl_entry_invalid(xattr);

	p = value + sizeof(bch_acl_header);
	while (p < end) {
		const bch_acl_entry *entry = p;

		if (p + sizeof(bch_acl_entry_short) > end)
			return acl_entry_invalid(xattr);

		switch (le16_to_cpu(entry->e_tag)) {
		case ACL_USER_OBJ:
		case ACL_GROUP_OBJ:
		case ACL_MASK:
		case ACL_OTHER:
			p += sizeof(bch_acl_entry_short);
			break;
		case ACL_USER:
		case ACL_GROUP:
			p += sizeof(bch_acl_entry);
			break;
		default:
			return acl_entry_invalid(xattr);
		}

		count++;
	}

	if (p > end)
		return acl_entry_invalid(xattr);

	if (!count)
		return NULL;

	acl = allocate_dropping_locks(trans, ret,
			posix_acl_alloc(count, _gfp));
	if (!acl && !ret)
		ret = bch_err_throw(trans->c, ENOMEM_acl);
	if (ret) {
		kfree(acl);
		return ERR_PTR(ret);
	}

	out = acl->a_entries;

	p = value + sizeof(bch_acl_header);
	while (p < end) {
		const bch_acl_entry *in = p;

		out->e_tag  = le16_to_cpu(in->e_tag);
		out->e_perm = le16_to_cpu(in->e_perm);

		switch (out->e_tag) {
		case ACL_USER_OBJ:
		case ACL_GROUP_OBJ:
		case ACL_MASK:
		case ACL_OTHER:
			p += sizeof(bch_acl_entry_short);
			break;
		case ACL_USER:
			out->e_uid = make_kuid(&init_user_ns,
					       le32_to_cpu(in->e_id));
			p += sizeof(bch_acl_entry);
			break;
		case ACL_GROUP:
			out->e_gid = make_kgid(&init_user_ns,
					       le32_to_cpu(in->e_id));
			p += sizeof(bch_acl_entry);
			break;
		}

		out++;
	}

	BUG_ON(out != acl->a_entries + acl->a_count);

	return acl;
}

/*
 * Convert from in-memory to filesystem representation.
 */
static struct bkey_i_xattr *
bch2_acl_to_xattr(struct btree_trans *trans,
		  const struct posix_acl *acl,
		  int type)
{
	struct bkey_i_xattr *xattr;
	bch_acl_header *acl_header;
	const struct posix_acl_entry *acl_e, *pe;
	void *outptr;
	unsigned nr_short = 0, nr_long = 0, acl_len, u64s;

	FOREACH_ACL_ENTRY(acl_e, acl, pe) {
		switch (acl_e->e_tag) {
		case ACL_USER:
		case ACL_GROUP:
			nr_long++;
			break;
		case ACL_USER_OBJ:
		case ACL_GROUP_OBJ:
		case ACL_MASK:
		case ACL_OTHER:
			nr_short++;
			break;
		default:
			return ERR_PTR(-EINVAL);
		}
	}

	acl_len = bch2_acl_size(nr_short, nr_long);
	u64s = BKEY_U64s + xattr_val_u64s(0, acl_len);

	if (u64s > U8_MAX)
		return ERR_PTR(-E2BIG);

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

	bkey_xattr_init(&xattr->k_i);
	xattr->k.u64s		= u64s;
	xattr->v.x_type		= acl_to_xattr_type(type);
	xattr->v.x_name_len	= 0;
	xattr->v.x_val_len	= cpu_to_le16(acl_len);

	acl_header = xattr_val(&xattr->v);
	acl_header->a_version = cpu_to_le32(BCH_ACL_VERSION);

	outptr = (void *) acl_header + sizeof(*acl_header);

	FOREACH_ACL_ENTRY(acl_e, acl, pe) {
		bch_acl_entry *entry = outptr;

		entry->e_tag = cpu_to_le16(acl_e->e_tag);
		entry->e_perm = cpu_to_le16(acl_e->e_perm);
		switch (acl_e->e_tag) {
		case ACL_USER:
			entry->e_id = cpu_to_le32(
				from_kuid(&init_user_ns, acl_e->e_uid));
			outptr += sizeof(bch_acl_entry);
			break;
		case ACL_GROUP:
			entry->e_id = cpu_to_le32(
				from_kgid(&init_user_ns, acl_e->e_gid));
			outptr += sizeof(bch_acl_entry);
			break;

		case ACL_USER_OBJ:
		case ACL_GROUP_OBJ:
		case ACL_MASK:
		case ACL_OTHER:
			outptr += sizeof(bch_acl_entry_short);
			break;
		}
	}

	BUG_ON(outptr != xattr_val(&xattr->v) + acl_len);

	return xattr;
}

struct posix_acl *bch2_get_acl(struct inode *vinode, int type, bool rcu)
{
	struct bch_inode_info *inode = to_bch_ei(vinode);
	struct bch_fs *c = inode->v.i_sb->s_fs_info;

	if (rcu)
		return ERR_PTR(-ECHILD);

	/*
	 * Fast path: if the inode flag for this ACL type is clear, no acl
	 * xattr exists and we can skip the btree lookup. Also populate the
	 * VFS negative cache, so subsequent permission checks on this inode
	 * short-circuit at the VFS layer:
	 */
	u64 flag = type == ACL_TYPE_ACCESS
		? BCH_INODE_has_access_acl
		: BCH_INODE_has_default_acl;
	if (!(inode->ei_inode.bi_flags & flag)) {
		set_cached_acl(&inode->v, type, NULL);
		return NULL;
	}

	struct bch_hash_info hash;
	struct xattr_search_key search = X_SEARCH(acl_to_xattr_type(type), "", 0);

	CLASS(btree_trans, trans)(c);
	CLASS(btree_iter_uninit, iter)(trans);
	struct bkey_s_c k;
	int ret = bch2_hash_info_init(c, &inode->ei_inode, &hash) ?:
		lockrestart_do(trans,
			bkey_err(k = bch2_hash_lookup(trans, &iter, bch2_xattr_hash_desc,
					     &hash, inode_inum(inode), &search, 0)));
	if (ret) {
		if (bch2_err_matches(ret, ENOENT)) {
			set_cached_acl(&inode->v, type, NULL);
			return NULL;
		}
		return ERR_PTR(ret);
	}

	struct bkey_s_c_xattr xattr = bkey_s_c_to_xattr(k);
	struct posix_acl *acl = bch2_acl_from_disk(trans, xattr);
	ret = PTR_ERR_OR_ZERO(acl);
	if (ret)
		return ERR_PTR(ret);

	set_cached_acl(&inode->v, type, acl);
	return acl;
}

int bch2_set_acl_trans(struct btree_trans *trans, subvol_inum inum,
		       struct bch_inode_unpacked *inode_u,
		       struct posix_acl *acl, int type)
{
	struct bch_hash_info hash_info;
	try(bch2_hash_info_init(trans->c, inode_u, &hash_info));

	if (type == ACL_TYPE_DEFAULT &&
	    !S_ISDIR(inode_u->bi_mode))
		return acl ? -EACCES : 0;

	int ret;
	if (acl) {
		struct bkey_i_xattr *xattr =
			bch2_acl_to_xattr(trans, acl, type);
		if (IS_ERR(xattr))
			return PTR_ERR(xattr);

		ret = bch2_hash_set(trans, bch2_xattr_hash_desc, &hash_info,
				    inum, &xattr->k_i, 0);
	} else {
		struct xattr_search_key search =
			X_SEARCH(acl_to_xattr_type(type), "", 0);

		ret = bch2_hash_delete(trans, bch2_xattr_hash_desc, &hash_info,
				       inum, &search);
		if (bch2_err_matches(ret, ENOENT))
			ret = 0;
	}

	if (ret)
		return ret;

	u64 flag = type == ACL_TYPE_ACCESS
		? BCH_INODE_has_access_acl
		: BCH_INODE_has_default_acl;
	if (acl)
		inode_u->bi_flags |=  flag;
	else
		inode_u->bi_flags &= ~flag;

	return 0;
}

static int __bch2_set_acl(struct btree_trans *trans,
			  struct mnt_idmap *idmap,
			  struct bch_inode_info *inode,
			  struct posix_acl *acl, int type)
{
	u32 snapshot;
	try(bch2_subvol_is_ro_trans(trans, inode_inum(inode).subvol, &snapshot));

	CLASS(btree_iter_uninit, inode_iter)(trans);
	struct bch_inode_unpacked inode_u;
	try(bch2_inode_peek(trans, &inode_iter, &inode_u, inode_inum(inode), BTREE_ITER_intent));

	umode_t mode = inode_u.bi_mode;

	if (type == ACL_TYPE_ACCESS)
		try(posix_acl_update_mode(idmap, &inode->v, &mode, &acl));

	try(bch2_set_acl_trans(trans, inode_inum(inode), &inode_u, acl, type));

	inode_u.bi_ctime	= bch2_current_time(trans->c);
	inode_u.bi_mode		= mode;

	try(bch2_inode_write(trans, &inode_iter, &inode_u));
	try(bch2_trans_commit(trans, NULL, NULL, 0));

	bch2_inode_update_after_write(trans, inode, &inode_u, ATTR_CTIME|ATTR_MODE);
	set_cached_acl(&inode->v, type, acl);
	return 0;
}

int bch2_set_acl(struct mnt_idmap *idmap,
		 struct dentry *dentry,
		 struct posix_acl *acl, int type)
{
	struct bch_inode_info *inode = to_bch_ei(dentry->d_inode);
	struct bch_fs *c = inode->v.i_sb->s_fs_info;

	guard(mutex)(&inode->ei_update_lock);
	CLASS(btree_trans, trans)(c);
	return bch2_err_class(lockrestart_do(trans, __bch2_set_acl(trans, idmap, inode, acl, type)));
}

int bch2_acl_chmod(struct btree_trans *trans, subvol_inum inum,
		   struct bch_inode_unpacked *inode,
		   umode_t mode,
		   struct posix_acl **new_acl)
{
	struct bch_hash_info hash_info;
	try(bch2_hash_info_init(trans->c, inode, &hash_info));

	struct xattr_search_key search = X_SEARCH(KEY_TYPE_XATTR_INDEX_POSIX_ACL_ACCESS, "", 0);

	CLASS(btree_iter_uninit, iter)(trans);
	struct bkey_s_c k = bch2_hash_lookup(trans, &iter, bch2_xattr_hash_desc,
			       &hash_info, inum, &search, BTREE_ITER_intent);
	int ret = bkey_err(k);
	if (ret)
		return bch2_err_matches(ret, ENOENT) ? 0 : ret;

	struct bkey_s_c_xattr xattr = bkey_s_c_to_xattr(k);

	struct posix_acl *acl __free(kfree) = errptr_try(bch2_acl_from_disk(trans, xattr));

	try(allocate_dropping_locks_errcode(trans, __posix_acl_chmod(&acl, _gfp, mode)));

	struct bkey_i_xattr *new = errptr_try(bch2_acl_to_xattr(trans, acl, ACL_TYPE_ACCESS));

	new->k.p = iter.pos;
	ret = bch2_trans_update(trans, &iter, &new->k_i, 0);
	*new_acl = acl;
	acl = NULL;
	return 0;
}

#endif /* NO_BCACHEFS_FS */
