// 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 const char *erofs_xattr_prefix(unsigned int idx, struct dentry *dentry);

static int erofs_init_inode_xattrs(struct inode *inode)
{
        struct erofs_buf buf = __EROFS_BUF_INITIALIZER;
        struct erofs_inode *vi = EROFS_I(inode);
        struct super_block *sb = inode->i_sb;
        const struct erofs_xattr_ibody_header *ih;
        __le32 *xattr_id;
        erofs_off_t pos;
        unsigned int i;
        int ret = 0;

        if (!vi->xattr_isize)
                return -ENODATA;

        /* 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)) {
                erofs_err(sb, "bogus xattr ibody @ nid %llu", vi->nid);
                DBG_BUGON(1);
                ret = -EFSCORRUPTED;
                goto out_unlock;
        }

        pos = erofs_iloc(inode) + vi->inode_isize;
        ih = erofs_read_metabuf(&buf, sb, pos, erofs_inode_in_metabox(inode));
        if (IS_ERR(ih)) {
                ret = PTR_ERR(ih);
                goto out_unlock;
        }
        vi->xattr_name_filter = le32_to_cpu(ih->h_name_filter);
        vi->xattr_shared_count = ih->h_shared_count;
        vi->xattr_shared_xattrs = kmalloc_objs(uint, vi->xattr_shared_count);
        if (!vi->xattr_shared_xattrs) {
                erofs_put_metabuf(&buf);
                ret = -ENOMEM;
                goto out_unlock;
        }

        /* skip the ibody header and read the shared xattr array */
        pos += sizeof(struct erofs_xattr_ibody_header);
        for (i = 0; i < vi->xattr_shared_count; ++i) {
                xattr_id = erofs_bread(&buf, pos + i * sizeof(__le32), true);
                if (IS_ERR(xattr_id)) {
                        kfree(vi->xattr_shared_xattrs);
                        vi->xattr_shared_xattrs = NULL;
                        ret = PTR_ERR(xattr_id);
                        goto out_unlock;
                }
                vi->xattr_shared_xattrs[i] = le32_to_cpu(*xattr_id);
        }
        erofs_put_metabuf(&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 int erofs_xattr_copy_to_buffer(struct erofs_xattr_iter *it,
                                      unsigned int len)
{
        unsigned int slice, processed;
        struct super_block *sb = it->sb;

        for (processed = 0; processed < len; processed += slice) {
                it->kaddr = erofs_bread(&it->buf, it->pos, true);
                if (IS_ERR(it->kaddr))
                        return PTR_ERR(it->kaddr);

                slice = min_t(unsigned int, sb->s_blocksize -
                                erofs_blkoff(sb, it->pos), len - processed);
                memcpy(it->buffer + it->buffer_ofs, it->kaddr, 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;
        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;
        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 -ENODATA;

                if (it->index != pf->prefix->base_index ||
                    it->name.len != entry.e_name_len + pf->infix_len)
                        return -ENODATA;

                if (memcmp(it->name.name, pf->prefix->infix, pf->infix_len))
                        return -ENODATA;

                it->infix_len = pf->infix_len;
        } else {
                if (it->index != entry.e_name_index ||
                    it->name.len != entry.e_name_len)
                        return -ENODATA;

                it->infix_len = 0;
        }

        /* 2. handle xattr name */
        for (processed = 0; processed < entry.e_name_len; processed += slice) {
                it->kaddr = erofs_bread(&it->buf, it->pos, true);
                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, slice))
                        return -ENODATA;
                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 -ENODATA;
        }

        ret = erofs_init_metabuf(&it->buf, it->sb, erofs_inode_in_metabox(inode));
        if (ret)
                return ret;
        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, it->pos, true);
                if (IS_ERR(it->kaddr))
                        return PTR_ERR(it->kaddr);

                entry_sz = erofs_xattr_entry_size(it->kaddr);
                /* 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 != -ENODATA) || (!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 = 0;
        int ret;

        ret = erofs_init_metabuf(&it->buf, sb,
                                 erofs_sb_has_shared_ea_in_metabox(sbi));
        if (ret)
                return ret;

        while (i < vi->xattr_shared_count) {
                it->pos = erofs_pos(sb, sbi->xattr_blkaddr) +
                                vi->xattr_shared_xattrs[i++] * sizeof(__le32);
                it->kaddr = erofs_bread(&it->buf, it->pos, true);
                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 != -ENODATA) || (!getxattr && ret))
                        break;
        }
        return i ? ret : -ENODATA;
}

static 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 -ENODATA;
        }

        it.index = index;
        it.name = QSTR(name);
        if (it.name.len > EROFS_NAME_LEN)
                return -ERANGE;

        it.sb = inode->i_sb;
        it.buf = __EROFS_BUF_INITIALIZER;
        it.buffer = buffer;
        it.buffer_size = buffer_size;
        it.buffer_ofs = 0;

        ret = erofs_xattr_iter_inline(&it, inode, true);
        if (ret == -ENODATA)
                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 == -ENODATA)
                return 0;
        if (ret)
                return ret;

        it.sb = dentry->d_sb;
        it.buf = __EROFS_BUF_INITIALIZER;
        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 == -ENODATA)
                ret = erofs_xattr_iter_shared(&it, inode, false);
        if (ret == -ENODATA)
                ret = 0;
        erofs_put_metabuf(&it.buf);
        return ret ? ret : it.buffer_ofs;
}

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);
}

static 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,
};

static 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
static const struct xattr_handler erofs_xattr_security_handler = {
        .prefix = XATTR_SECURITY_PREFIX,
        .flags  = EROFS_XATTR_INDEX_SECURITY,
        .get    = erofs_xattr_generic_get,
};
#endif

const struct xattr_handler * const erofs_xattr_handlers[] = {
        &erofs_xattr_user_handler,
        &erofs_xattr_trusted_handler,
#ifdef CONFIG_EROFS_FS_SECURITY
        &erofs_xattr_security_handler,
#endif
        NULL,
};

static const char *erofs_xattr_prefix(unsigned int idx, struct dentry *dentry)
{
        static const struct xattr_handler * const xattr_handler_map[] = {
                [EROFS_XATTR_INDEX_USER] = &erofs_xattr_user_handler,
#ifdef CONFIG_EROFS_FS_POSIX_ACL
                [EROFS_XATTR_INDEX_POSIX_ACL_ACCESS] = &nop_posix_acl_access,
                [EROFS_XATTR_INDEX_POSIX_ACL_DEFAULT] = &nop_posix_acl_default,
#endif
                [EROFS_XATTR_INDEX_TRUSTED] = &erofs_xattr_trusted_handler,
#ifdef CONFIG_EROFS_FS_SECURITY
                [EROFS_XATTR_INDEX_SECURITY] = &erofs_xattr_security_handler,
#endif
        };
        const struct xattr_handler *handler = NULL;

        if (idx && idx < ARRAY_SIZE(xattr_handler_map)) {
                handler = xattr_handler_map[idx];
                if (xattr_handler_can_list(handler, dentry))
                        return xattr_prefix(handler);
        }
        return NULL;
}

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;
        bool plain = erofs_sb_has_plain_xattr_pfx(sbi);

        if (!sbi->xattr_prefix_count)
                return 0;

        pfs = kzalloc_objs(*pfs, sbi->xattr_prefix_count);
        if (!pfs)
                return -ENOMEM;

        if (!plain) {
                if (erofs_sb_has_metabox(sbi))
                        (void)erofs_init_metabuf(&buf, sb, true);
                else if (sbi->packed_inode)
                        buf.mapping = sbi->packed_inode->i_mapping;
                else
                        plain = true;
        }
        if (plain)
                (void)erofs_init_metabuf(&buf, sb, false);

        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);
        if (!ret && erofs_sb_has_ishare_xattrs(sbi)) {
                struct erofs_xattr_prefix_item *pf = pfs + sbi->ishare_xattr_prefix_id;
                struct erofs_xattr_long_prefix *newpfx;

                newpfx = krealloc(pf->prefix,
                        sizeof(*newpfx) + pf->infix_len + 1, GFP_KERNEL);
                if (newpfx) {
                        newpfx->infix[pf->infix_len] = '\0';
                        pf->prefix = newpfx;
                } else {
                        ret = -ENOMEM;
                }
        }
        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 == -ENODATA)
                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;
}

bool erofs_inode_has_noacl(struct inode *inode, void *kaddr, unsigned int ofs)
{
        static const unsigned int bitmask =
                BIT(21) |       /* system.posix_acl_default */
                BIT(30);        /* system.posix_acl_access */
        struct erofs_sb_info *sbi = EROFS_I_SB(inode);
        const struct erofs_xattr_ibody_header *ih = kaddr + ofs;

        if (EROFS_I(inode)->xattr_isize < sizeof(*ih))
                return true;

        if (erofs_sb_has_xattr_filter(sbi) && !sbi->xattr_filter_reserved &&
            !check_add_overflow(ofs, sizeof(*ih), &ofs) &&
            ofs <= i_blocksize(inode)) {
                if ((le32_to_cpu(ih->h_name_filter) & bitmask) == bitmask)
                        return true;
        }
        return false;
}
#endif

#ifdef CONFIG_EROFS_FS_PAGE_CACHE_SHARE
int erofs_xattr_fill_inode_fingerprint(struct erofs_inode_fingerprint *fp,
                                       struct inode *inode, const char *domain_id)
{
        struct erofs_sb_info *sbi = EROFS_SB(inode->i_sb);
        struct erofs_xattr_prefix_item *prefix;
        const char *infix;
        int valuelen, base_index;

        if (!test_opt(&sbi->opt, INODE_SHARE))
                return -EOPNOTSUPP;
        if (!sbi->xattr_prefixes)
                return -EINVAL;
        prefix = sbi->xattr_prefixes + sbi->ishare_xattr_prefix_id;
        infix = prefix->prefix->infix;
        base_index = prefix->prefix->base_index;
        valuelen = erofs_getxattr(inode, base_index, infix, NULL, 0);
        if (valuelen <= 0 || valuelen > (1 << sbi->blkszbits))
                return -EFSCORRUPTED;
        fp->size = valuelen + (domain_id ? strlen(domain_id) : 0);
        fp->opaque = kmalloc(fp->size, GFP_KERNEL);
        if (!fp->opaque)
                return -ENOMEM;
        if (valuelen != erofs_getxattr(inode, base_index, infix,
                                       fp->opaque, valuelen)) {
                kfree(fp->opaque);
                fp->opaque = NULL;
                return -EFSCORRUPTED;
        }
        memcpy(fp->opaque + valuelen, domain_id, fp->size - valuelen);
        return 0;
}
#endif