// SPDX-License-Identifier: GPL-2.0
/*
 * (C) 2001 Clemson University and The University of Chicago
 * Copyright 2018 Omnibond Systems, L.L.C.
 *
 * See COPYING in top-level directory.
 */

/*
 *  Linux VFS extended attribute operations.
 */

#include "protocol.h"
#include "orangefs-kernel.h"
#include "orangefs-bufmap.h"
#include <linux/posix_acl_xattr.h>
#include <linux/xattr.h>
#include <linux/hashtable.h>

#define SYSTEM_ORANGEFS_KEY "system.pvfs2."
#define SYSTEM_ORANGEFS_KEY_LEN 13

/*
 * this function returns
 *   0 if the key corresponding to name is not meant to be printed as part
 *     of a listxattr.
 *   1 if the key corresponding to name is meant to be returned as part of
 *     a listxattr.
 * The ones that start SYSTEM_ORANGEFS_KEY are the ones to avoid printing.
 */
static int is_reserved_key(const char *key, size_t size)
{

        if (size < SYSTEM_ORANGEFS_KEY_LEN)
                return 1;

        return strncmp(key, SYSTEM_ORANGEFS_KEY, SYSTEM_ORANGEFS_KEY_LEN) ?  1 : 0;
}

static inline int convert_to_internal_xattr_flags(int setxattr_flags)
{
        int internal_flag = 0;

        if (setxattr_flags & XATTR_REPLACE) {
                /* Attribute must exist! */
                internal_flag = ORANGEFS_XATTR_REPLACE;
        } else if (setxattr_flags & XATTR_CREATE) {
                /* Attribute must not exist */
                internal_flag = ORANGEFS_XATTR_CREATE;
        }
        return internal_flag;
}

static unsigned int xattr_key(const char *key)
{
        unsigned int i = 0;
        if (!key)
                return 0;
        while (*key)
                i += *key++;
        return i % 16;
}

static struct orangefs_cached_xattr *find_cached_xattr(struct inode *inode,
    const char *key)
{
        struct orangefs_inode_s *orangefs_inode = ORANGEFS_I(inode);
        struct orangefs_cached_xattr *cx;
        struct hlist_head *h;
        struct hlist_node *tmp;
        h = &orangefs_inode->xattr_cache[xattr_key(key)];
        if (hlist_empty(h))
                return NULL;
        hlist_for_each_entry_safe(cx, tmp, h, node) {
/*              if (!time_before(jiffies, cx->timeout)) {
                        hlist_del(&cx->node);
                        kfree(cx);
                        continue;
                }*/
                if (!strcmp(cx->key, key))
                        return cx;
        }
        return NULL;
}

/*
 * Tries to get a specified key's attributes of a given
 * file into a user-specified buffer. Note that the getxattr
 * interface allows for the users to probe the size of an
 * extended attribute by passing in a value of 0 to size.
 * Thus our return value is always the size of the attribute
 * unless the key does not exist for the file and/or if
 * there were errors in fetching the attribute value.
 */
ssize_t orangefs_inode_getxattr(struct inode *inode, const char *name,
                                void *buffer, size_t size)
{
        struct orangefs_inode_s *orangefs_inode = ORANGEFS_I(inode);
        struct orangefs_kernel_op_s *new_op = NULL;
        struct orangefs_cached_xattr *cx;
        ssize_t ret = -ENOMEM;
        ssize_t length = 0;
        int fsuid;
        int fsgid;

        gossip_debug(GOSSIP_XATTR_DEBUG,
                     "%s: name %s, buffer_size %zd\n",
                     __func__, name, size);

        if (S_ISLNK(inode->i_mode))
                return -EOPNOTSUPP;

        if (strlen(name) >= ORANGEFS_MAX_XATTR_NAMELEN)
                return -EINVAL;

        fsuid = from_kuid(&init_user_ns, current_fsuid());
        fsgid = from_kgid(&init_user_ns, current_fsgid());

        gossip_debug(GOSSIP_XATTR_DEBUG,
                     "getxattr on inode %pU, name %s "
                     "(uid %o, gid %o)\n",
                     get_khandle_from_ino(inode),
                     name,
                     fsuid,
                     fsgid);

        down_read(&orangefs_inode->xattr_sem);

        cx = find_cached_xattr(inode, name);
        if (cx && time_before(jiffies, cx->timeout)) {
                if (cx->length == -1) {
                        ret = -ENODATA;
                        goto out_unlock;
                } else {
                        if (size == 0) {
                                ret = cx->length;
                                goto out_unlock;
                        }
                        if (cx->length > size) {
                                ret = -ERANGE;
                                goto out_unlock;
                        }
                        memcpy(buffer, cx->val, cx->length);
                        memset(buffer + cx->length, 0, size - cx->length);
                        ret = cx->length;
                        goto out_unlock;
                }
        }

        new_op = op_alloc(ORANGEFS_VFS_OP_GETXATTR);
        if (!new_op)
                goto out_unlock;

        new_op->upcall.req.getxattr.refn = orangefs_inode->refn;
        strscpy(new_op->upcall.req.getxattr.key, name);

        /*
         * NOTE: Although keys are meant to be NULL terminated textual
         * strings, I am going to explicitly pass the length just in case
         * we change this later on...
         */
        new_op->upcall.req.getxattr.key_sz = strlen(name) + 1;

        ret = service_operation(new_op, "orangefs_inode_getxattr",
                                get_interruptible_flag(inode));
        if (ret != 0) {
                if (ret == -ENOENT) {
                        ret = -ENODATA;
                        gossip_debug(GOSSIP_XATTR_DEBUG,
                                     "orangefs_inode_getxattr: inode %pU key %s"
                                     " does not exist!\n",
                                     get_khandle_from_ino(inode),
                                     (char *)new_op->upcall.req.getxattr.key);
                        cx = kmalloc_obj(*cx);
                        if (cx) {
                                strscpy(cx->key, name);
                                cx->length = -1;
                                cx->timeout = jiffies +
                                    orangefs_getattr_timeout_msecs*HZ/1000;
                                hlist_add_head( &cx->node,
                                   &orangefs_inode->xattr_cache[xattr_key(cx->key)]);
                        }
                }
                goto out_release_op;
        }

        /*
         * Length returned includes null terminator.
         */
        length = new_op->downcall.resp.getxattr.val_sz;

        /*
         * Just return the length of the queried attribute.
         */
        if (size == 0) {
                ret = length;
                goto out_release_op;
        }

        /*
         * Check to see if key length is > provided buffer size.
         */
        if (length > size) {
                ret = -ERANGE;
                goto out_release_op;
        }

        memcpy(buffer, new_op->downcall.resp.getxattr.val, length);
        memset(buffer + length, 0, size - length);
        gossip_debug(GOSSIP_XATTR_DEBUG,
             "orangefs_inode_getxattr: inode %pU "
             "key %s key_sz %d, val_len %d\n",
             get_khandle_from_ino(inode),
             (char *)new_op->
                upcall.req.getxattr.key,
                     (int)new_op->
                upcall.req.getxattr.key_sz,
             (int)ret);

        ret = length;

        if (cx) {
                strscpy(cx->key, name);
                memcpy(cx->val, buffer, length);
                cx->length = length;
                cx->timeout = jiffies + HZ;
        } else {
                cx = kmalloc_obj(*cx);
                if (cx) {
                        strscpy(cx->key, name);
                        memcpy(cx->val, buffer, length);
                        cx->length = length;
                        cx->timeout = jiffies + HZ;
                        hlist_add_head(&cx->node,
                                &orangefs_inode->xattr_cache[xattr_key(cx->key)]);
                }
        }

out_release_op:
        op_release(new_op);
out_unlock:
        up_read(&orangefs_inode->xattr_sem);
        return ret;
}

static int orangefs_inode_removexattr(struct inode *inode, const char *name,
                                      int flags)
{
        struct orangefs_inode_s *orangefs_inode = ORANGEFS_I(inode);
        struct orangefs_kernel_op_s *new_op = NULL;
        struct orangefs_cached_xattr *cx;
        struct hlist_head *h;
        struct hlist_node *tmp;
        int ret = -ENOMEM;

        if (strlen(name) >= ORANGEFS_MAX_XATTR_NAMELEN)
                return -EINVAL;

        down_write(&orangefs_inode->xattr_sem);
        new_op = op_alloc(ORANGEFS_VFS_OP_REMOVEXATTR);
        if (!new_op)
                goto out_unlock;

        new_op->upcall.req.removexattr.refn = orangefs_inode->refn;
        /*
         * NOTE: Although keys are meant to be NULL terminated
         * textual strings, I am going to explicitly pass the
         * length just in case we change this later on...
         */
        strscpy(new_op->upcall.req.removexattr.key, name);
        new_op->upcall.req.removexattr.key_sz = strlen(name) + 1;

        gossip_debug(GOSSIP_XATTR_DEBUG,
                     "orangefs_inode_removexattr: key %s, key_sz %d\n",
                     (char *)new_op->upcall.req.removexattr.key,
                     (int)new_op->upcall.req.removexattr.key_sz);

        ret = service_operation(new_op,
                                "orangefs_inode_removexattr",
                                get_interruptible_flag(inode));
        if (ret == -ENOENT) {
                /*
                 * Request to replace a non-existent attribute is an error.
                 */
                if (flags & XATTR_REPLACE)
                        ret = -ENODATA;
                else
                        ret = 0;
        }

        gossip_debug(GOSSIP_XATTR_DEBUG,
                     "orangefs_inode_removexattr: returning %d\n", ret);

        op_release(new_op);

        h = &orangefs_inode->xattr_cache[xattr_key(name)];
        hlist_for_each_entry_safe(cx, tmp, h, node) {
                if (!strcmp(cx->key, name)) {
                        hlist_del(&cx->node);
                        kfree(cx);
                        break;
                }
        }

out_unlock:
        up_write(&orangefs_inode->xattr_sem);
        return ret;
}

/*
 * Tries to set an attribute for a given key on a file.
 *
 * Returns a -ve number on error and 0 on success.  Key is text, but value
 * can be binary!
 */
int orangefs_inode_setxattr(struct inode *inode, const char *name,
                            const void *value, size_t size, int flags)
{
        struct orangefs_inode_s *orangefs_inode = ORANGEFS_I(inode);
        struct orangefs_kernel_op_s *new_op;
        int internal_flag = 0;
        struct orangefs_cached_xattr *cx;
        struct hlist_head *h;
        struct hlist_node *tmp;
        int ret = -ENOMEM;

        gossip_debug(GOSSIP_XATTR_DEBUG,
                     "%s: name %s, buffer_size %zd\n",
                     __func__, name, size);

        if (size > ORANGEFS_MAX_XATTR_VALUELEN)
                return -EINVAL;
        if (strlen(name) >= ORANGEFS_MAX_XATTR_NAMELEN)
                return -EINVAL;

        internal_flag = convert_to_internal_xattr_flags(flags);

        /* This is equivalent to a removexattr */
        if (size == 0 && !value) {
                gossip_debug(GOSSIP_XATTR_DEBUG,
                             "removing xattr (%s)\n",
                             name);
                return orangefs_inode_removexattr(inode, name, flags);
        }

        gossip_debug(GOSSIP_XATTR_DEBUG,
                     "setxattr on inode %pU, name %s\n",
                     get_khandle_from_ino(inode),
                     name);

        down_write(&orangefs_inode->xattr_sem);
        new_op = op_alloc(ORANGEFS_VFS_OP_SETXATTR);
        if (!new_op)
                goto out_unlock;


        new_op->upcall.req.setxattr.refn = orangefs_inode->refn;
        new_op->upcall.req.setxattr.flags = internal_flag;
        /*
         * NOTE: Although keys are meant to be NULL terminated textual
         * strings, I am going to explicitly pass the length just in
         * case we change this later on...
         */
        strscpy(new_op->upcall.req.setxattr.keyval.key, name);
        new_op->upcall.req.setxattr.keyval.key_sz = strlen(name) + 1;
        memcpy(new_op->upcall.req.setxattr.keyval.val, value, size);
        new_op->upcall.req.setxattr.keyval.val_sz = size;

        gossip_debug(GOSSIP_XATTR_DEBUG,
                     "orangefs_inode_setxattr: key %s, key_sz %d "
                     " value size %zd\n",
                     (char *)new_op->upcall.req.setxattr.keyval.key,
                     (int)new_op->upcall.req.setxattr.keyval.key_sz,
                     size);

        ret = service_operation(new_op,
                                "orangefs_inode_setxattr",
                                get_interruptible_flag(inode));

        gossip_debug(GOSSIP_XATTR_DEBUG,
                     "orangefs_inode_setxattr: returning %d\n",
                     ret);

        /* when request is serviced properly, free req op struct */
        op_release(new_op);

        h = &orangefs_inode->xattr_cache[xattr_key(name)];
        hlist_for_each_entry_safe(cx, tmp, h, node) {
                if (!strcmp(cx->key, name)) {
                        hlist_del(&cx->node);
                        kfree(cx);
                        break;
                }
        }

out_unlock:
        up_write(&orangefs_inode->xattr_sem);
        return ret;
}

/*
 * Tries to get a specified object's keys into a user-specified buffer of a
 * given size.  Note that like the previous instances of xattr routines, this
 * also allows you to pass in a NULL pointer and 0 size to probe the size for
 * subsequent memory allocations. Thus our return value is always the size of
 * all the keys unless there were errors in fetching the keys!
 */
ssize_t orangefs_listxattr(struct dentry *dentry, char *buffer, size_t size)
{
        struct inode *inode = dentry->d_inode;
        struct orangefs_inode_s *orangefs_inode = ORANGEFS_I(inode);
        struct orangefs_kernel_op_s *new_op;
        __u64 token = ORANGEFS_ITERATE_START;
        ssize_t ret = -ENOMEM;
        ssize_t total = 0;
        int count_keys = 0;
        int key_size;
        int i = 0;
        int returned_count = 0;

        if (size > 0 && !buffer) {
                gossip_err("%s: bogus NULL pointers\n", __func__);
                return -EINVAL;
        }

        down_read(&orangefs_inode->xattr_sem);
        new_op = op_alloc(ORANGEFS_VFS_OP_LISTXATTR);
        if (!new_op)
                goto out_unlock;

        if (buffer && size > 0)
                memset(buffer, 0, size);

try_again:
        key_size = 0;
        new_op->upcall.req.listxattr.refn = orangefs_inode->refn;
        new_op->upcall.req.listxattr.token = token;
        new_op->upcall.req.listxattr.requested_count =
            (size == 0) ? 0 : ORANGEFS_MAX_XATTR_LISTLEN;
        ret = service_operation(new_op, __func__,
                                get_interruptible_flag(inode));
        if (ret != 0)
                goto done;

        if (size == 0) {
                /*
                 * This is a bit of a big upper limit, but I did not want to
                 * spend too much time getting this correct, since users end
                 * up allocating memory rather than us...
                 */
                total = new_op->downcall.resp.listxattr.returned_count *
                        ORANGEFS_MAX_XATTR_NAMELEN;
                goto done;
        }

        returned_count = new_op->downcall.resp.listxattr.returned_count;
        if (returned_count < 0 ||
            returned_count > ORANGEFS_MAX_XATTR_LISTLEN) {
                gossip_err("%s: impossible value for returned_count:%d:\n",
                __func__,
                returned_count);
                ret = -EIO;
                goto done;
        }

        /*
         * Check to see how much can be fit in the buffer. Fit only whole keys.
         */
        for (i = 0; i < returned_count; i++) {
                if (new_op->downcall.resp.listxattr.lengths[i] < 0 ||
                    new_op->downcall.resp.listxattr.lengths[i] >
                    ORANGEFS_MAX_XATTR_NAMELEN) {
                        gossip_err("%s: impossible value for lengths[%d]\n",
                            __func__,
                            new_op->downcall.resp.listxattr.lengths[i]);
                        ret = -EIO;
                        goto done;
                }
                if (total + new_op->downcall.resp.listxattr.lengths[i] > size)
                        goto done;

                /*
                 * Since many dumb programs try to setxattr() on our reserved
                 * xattrs this is a feeble attempt at defeating those by not
                 * listing them in the output of listxattr.. sigh
                 */
                if (is_reserved_key(new_op->downcall.resp.listxattr.key +
                                    key_size,
                                    new_op->downcall.resp.
                                        listxattr.lengths[i])) {
                        gossip_debug(GOSSIP_XATTR_DEBUG, "Copying key %d -> %s\n",
                                        i, new_op->downcall.resp.listxattr.key +
                                                key_size);
                        memcpy(buffer + total,
                                new_op->downcall.resp.listxattr.key + key_size,
                                new_op->downcall.resp.listxattr.lengths[i]);
                        total += new_op->downcall.resp.listxattr.lengths[i];
                        count_keys++;
                } else {
                        gossip_debug(GOSSIP_XATTR_DEBUG, "[RESERVED] key %d -> %s\n",
                                        i, new_op->downcall.resp.listxattr.key +
                                                key_size);
                }
                key_size += new_op->downcall.resp.listxattr.lengths[i];
        }

        /*
         * Since the buffer was large enough, we might have to continue
         * fetching more keys!
         */
        token = new_op->downcall.resp.listxattr.token;
        if (token != ORANGEFS_ITERATE_END)
                goto try_again;

done:
        gossip_debug(GOSSIP_XATTR_DEBUG, "%s: returning %d"
                     " [size of buffer %ld] (filled in %d keys)\n",
                     __func__,
                     ret ? (int)ret : (int)total,
                     (long)size,
                     count_keys);
        op_release(new_op);
        if (ret == 0)
                ret = total;
out_unlock:
        up_read(&orangefs_inode->xattr_sem);
        return ret;
}

static int orangefs_xattr_set_default(const struct xattr_handler *handler,
                                      struct mnt_idmap *idmap,
                                      struct dentry *unused,
                                      struct inode *inode,
                                      const char *name,
                                      const void *buffer,
                                      size_t size,
                                      int flags)
{
        return orangefs_inode_setxattr(inode, name, buffer, size, flags);
}

static int orangefs_xattr_get_default(const struct xattr_handler *handler,
                                      struct dentry *unused,
                                      struct inode *inode,
                                      const char *name,
                                      void *buffer,
                                      size_t size)
{
        return orangefs_inode_getxattr(inode, name, buffer, size);

}

static const struct xattr_handler orangefs_xattr_default_handler = {
        .prefix = "",  /* match any name => handlers called with full name */
        .get = orangefs_xattr_get_default,
        .set = orangefs_xattr_set_default,
};

const struct xattr_handler * const orangefs_xattr_handlers[] = {
        &orangefs_xattr_default_handler,
        NULL
};