// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2008 Christoph Hellwig.
 * Portions Copyright (C) 2000-2008 Silicon Graphics, Inc.
 */

#include "xfs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_log_format.h"
#include "xfs_da_format.h"
#include "xfs_inode.h"
#include "xfs_attr.h"

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


static int
xfs_xattr_get(const struct xattr_handler *handler, struct dentry *unused,
                struct inode *inode, const char *name, void *value, size_t size)
{
        int xflags = handler->flags;
        struct xfs_inode *ip = XFS_I(inode);
        int error, asize = size;

        /* Convert Linux syscall to XFS internal ATTR flags */
        if (!size) {
                xflags |= ATTR_KERNOVAL;
                value = NULL;
        }

        error = xfs_attr_get(ip, (unsigned char *)name, value, &asize, xflags);
        if (error)
                return error;
        return asize;
}

void
xfs_forget_acl(
        struct inode            *inode,
        const char              *name,
        int                     xflags)
{
        /*
         * Invalidate any cached ACLs if the user has bypassed the ACL
         * interface. We don't validate the content whatsoever so it is caller
         * responsibility to provide data in valid format and ensure i_mode is
         * consistent.
         */
        if (xflags & ATTR_ROOT) {
#ifdef CONFIG_XFS_POSIX_ACL
                if (!strcmp(name, SGI_ACL_FILE))
                        forget_cached_acl(inode, ACL_TYPE_ACCESS);
                else if (!strcmp(name, SGI_ACL_DEFAULT))
                        forget_cached_acl(inode, ACL_TYPE_DEFAULT);
#endif
        }
}

static int
xfs_xattr_set(const struct xattr_handler *handler, struct dentry *unused,
                struct inode *inode, const char *name, const void *value,
                size_t size, int flags)
{
        int                     xflags = handler->flags;
        struct xfs_inode        *ip = XFS_I(inode);
        int                     error;

        /* Convert Linux syscall to XFS internal ATTR flags */
        if (flags & XATTR_CREATE)
                xflags |= ATTR_CREATE;
        if (flags & XATTR_REPLACE)
                xflags |= ATTR_REPLACE;

        if (!value)
                return xfs_attr_remove(ip, (unsigned char *)name, xflags);
        error = xfs_attr_set(ip, (unsigned char *)name,
                                (void *)value, size, xflags);
        if (!error)
                xfs_forget_acl(inode, name, xflags);

        return error;
}

static const struct xattr_handler xfs_xattr_user_handler = {
        .prefix = XATTR_USER_PREFIX,
        .flags  = 0, /* no flags implies user namespace */
        .get    = xfs_xattr_get,
        .set    = xfs_xattr_set,
};

static const struct xattr_handler xfs_xattr_trusted_handler = {
        .prefix = XATTR_TRUSTED_PREFIX,
        .flags  = ATTR_ROOT,
        .get    = xfs_xattr_get,
        .set    = xfs_xattr_set,
};

static const struct xattr_handler xfs_xattr_security_handler = {
        .prefix = XATTR_SECURITY_PREFIX,
        .flags  = ATTR_SECURE,
        .get    = xfs_xattr_get,
        .set    = xfs_xattr_set,
};

const struct xattr_handler *xfs_xattr_handlers[] = {
        &xfs_xattr_user_handler,
        &xfs_xattr_trusted_handler,
        &xfs_xattr_security_handler,
#ifdef CONFIG_XFS_POSIX_ACL
        &posix_acl_access_xattr_handler,
        &posix_acl_default_xattr_handler,
#endif
        NULL
};

static void
__xfs_xattr_put_listent(
        struct xfs_attr_list_context *context,
        char *prefix,
        int prefix_len,
        unsigned char *name,
        int namelen)
{
        char *offset;
        int arraytop;

        if (context->count < 0 || context->seen_enough)
                return;

        if (!context->alist)
                goto compute_size;

        arraytop = context->count + prefix_len + namelen + 1;
        if (arraytop > context->firstu) {
                context->count = -1;    /* insufficient space */
                context->seen_enough = 1;
                return;
        }
        offset = (char *)context->alist + context->count;
        strncpy(offset, prefix, prefix_len);
        offset += prefix_len;
        strncpy(offset, (char *)name, namelen);                 /* real name */
        offset += namelen;
        *offset = '\0';

compute_size:
        context->count += prefix_len + namelen + 1;
        return;
}

static void
xfs_xattr_put_listent(
        struct xfs_attr_list_context *context,
        int             flags,
        unsigned char   *name,
        int             namelen,
        int             valuelen)
{
        char *prefix;
        int prefix_len;

        ASSERT(context->count >= 0);

        if (flags & XFS_ATTR_ROOT) {
#ifdef CONFIG_XFS_POSIX_ACL
                if (namelen == SGI_ACL_FILE_SIZE &&
                    strncmp(name, SGI_ACL_FILE,
                            SGI_ACL_FILE_SIZE) == 0) {
                        __xfs_xattr_put_listent(
                                        context, XATTR_SYSTEM_PREFIX,
                                        XATTR_SYSTEM_PREFIX_LEN,
                                        XATTR_POSIX_ACL_ACCESS,
                                        strlen(XATTR_POSIX_ACL_ACCESS));
                } else if (namelen == SGI_ACL_DEFAULT_SIZE &&
                         strncmp(name, SGI_ACL_DEFAULT,
                                 SGI_ACL_DEFAULT_SIZE) == 0) {
                        __xfs_xattr_put_listent(
                                        context, XATTR_SYSTEM_PREFIX,
                                        XATTR_SYSTEM_PREFIX_LEN,
                                        XATTR_POSIX_ACL_DEFAULT,
                                        strlen(XATTR_POSIX_ACL_DEFAULT));
                }
#endif

                /*
                 * Only show root namespace entries if we are actually allowed to
                 * see them.
                 */
                if (!capable(CAP_SYS_ADMIN))
                        return;

                prefix = XATTR_TRUSTED_PREFIX;
                prefix_len = XATTR_TRUSTED_PREFIX_LEN;
        } else if (flags & XFS_ATTR_SECURE) {
                prefix = XATTR_SECURITY_PREFIX;
                prefix_len = XATTR_SECURITY_PREFIX_LEN;
        } else {
                prefix = XATTR_USER_PREFIX;
                prefix_len = XATTR_USER_PREFIX_LEN;
        }

        __xfs_xattr_put_listent(context, prefix, prefix_len, name,
                                namelen);
        return;
}

ssize_t
xfs_vn_listxattr(
        struct dentry   *dentry,
        char            *data,
        size_t          size)
{
        struct xfs_attr_list_context context;
        struct attrlist_cursor_kern cursor = { 0 };
        struct inode    *inode = d_inode(dentry);
        int             error;

        /*
         * First read the regular on-disk attributes.
         */
        memset(&context, 0, sizeof(context));
        context.dp = XFS_I(inode);
        context.cursor = &cursor;
        context.resynch = 1;
        context.alist = size ? data : NULL;
        context.bufsize = size;
        context.firstu = context.bufsize;
        context.put_listent = xfs_xattr_put_listent;

        error = xfs_attr_list_int(&context);
        if (error)
                return error;
        if (context.count < 0)
                return -ERANGE;

        return context.count;
}