// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * linux/ipc/msgutil.c
 * Copyright (C) 1999, 2004 Manfred Spraul
 */

#include <linux/spinlock.h>
#include <linux/init.h>
#include <linux/security.h>
#include <linux/slab.h>
#include <linux/ipc.h>
#include <linux/msg.h>
#include <linux/ipc_namespace.h>
#include <linux/utsname.h>
#include <linux/proc_ns.h>
#include <linux/uaccess.h>
#include <linux/sched.h>
#include <linux/nstree.h>

#include "util.h"

DEFINE_SPINLOCK(mq_lock);

/*
 * The next 2 defines are here bc this is the only file
 * compiled when either CONFIG_SYSVIPC and CONFIG_POSIX_MQUEUE
 * and not CONFIG_IPC_NS.
 */
struct ipc_namespace init_ipc_ns = {
        .ns = NS_COMMON_INIT(init_ipc_ns),
        .user_ns = &init_user_ns,
};

struct msg_msgseg {
        struct msg_msgseg *next;
        /* the next part of the message follows immediately */
};

#define DATALEN_MSG     ((size_t)PAGE_SIZE-sizeof(struct msg_msg))
#define DATALEN_SEG     ((size_t)PAGE_SIZE-sizeof(struct msg_msgseg))

static kmem_buckets *msg_buckets __ro_after_init;

static int __init init_msg_buckets(void)
{
        msg_buckets = kmem_buckets_create("msg_msg", SLAB_ACCOUNT,
                                          sizeof(struct msg_msg),
                                          DATALEN_MSG, NULL);

        return 0;
}
subsys_initcall(init_msg_buckets);

static struct msg_msg *alloc_msg(size_t len)
{
        struct msg_msg *msg;
        struct msg_msgseg **pseg;
        size_t alen;

        alen = min(len, DATALEN_MSG);
        msg = kmem_buckets_alloc(msg_buckets, sizeof(*msg) + alen, GFP_KERNEL);
        if (msg == NULL)
                return NULL;

        msg->next = NULL;
        msg->security = NULL;

        len -= alen;
        pseg = &msg->next;
        while (len > 0) {
                struct msg_msgseg *seg;

                cond_resched();

                alen = min(len, DATALEN_SEG);
                seg = kmalloc(sizeof(*seg) + alen, GFP_KERNEL_ACCOUNT);
                if (seg == NULL)
                        goto out_err;
                *pseg = seg;
                seg->next = NULL;
                pseg = &seg->next;
                len -= alen;
        }

        return msg;

out_err:
        free_msg(msg);
        return NULL;
}

struct msg_msg *load_msg(const void __user *src, size_t len)
{
        struct msg_msg *msg;
        struct msg_msgseg *seg;
        int err = -EFAULT;
        size_t alen;

        msg = alloc_msg(len);
        if (msg == NULL)
                return ERR_PTR(-ENOMEM);

        alen = min(len, DATALEN_MSG);
        if (copy_from_user(msg + 1, src, alen))
                goto out_err;

        for (seg = msg->next; seg != NULL; seg = seg->next) {
                len -= alen;
                src = (char __user *)src + alen;
                alen = min(len, DATALEN_SEG);
                if (copy_from_user(seg + 1, src, alen))
                        goto out_err;
        }

        err = security_msg_msg_alloc(msg);
        if (err)
                goto out_err;

        return msg;

out_err:
        free_msg(msg);
        return ERR_PTR(err);
}
#ifdef CONFIG_CHECKPOINT_RESTORE
struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst)
{
        struct msg_msgseg *dst_pseg, *src_pseg;
        size_t len = src->m_ts;
        size_t alen;

        if (src->m_ts > dst->m_ts)
                return ERR_PTR(-EINVAL);

        alen = min(len, DATALEN_MSG);
        memcpy(dst + 1, src + 1, alen);

        for (dst_pseg = dst->next, src_pseg = src->next;
             src_pseg != NULL;
             dst_pseg = dst_pseg->next, src_pseg = src_pseg->next) {

                len -= alen;
                alen = min(len, DATALEN_SEG);
                memcpy(dst_pseg + 1, src_pseg + 1, alen);
        }

        dst->m_type = src->m_type;
        dst->m_ts = src->m_ts;

        return dst;
}
#else
struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst)
{
        return ERR_PTR(-ENOSYS);
}
#endif
int store_msg(void __user *dest, struct msg_msg *msg, size_t len)
{
        size_t alen;
        struct msg_msgseg *seg;

        alen = min(len, DATALEN_MSG);
        if (copy_to_user(dest, msg + 1, alen))
                return -1;

        for (seg = msg->next; seg != NULL; seg = seg->next) {
                len -= alen;
                dest = (char __user *)dest + alen;
                alen = min(len, DATALEN_SEG);
                if (copy_to_user(dest, seg + 1, alen))
                        return -1;
        }
        return 0;
}

void free_msg(struct msg_msg *msg)
{
        struct msg_msgseg *seg;

        security_msg_msg_free(msg);

        seg = msg->next;
        kfree(msg);
        while (seg != NULL) {
                struct msg_msgseg *tmp = seg->next;

                cond_resched();
                kfree(seg);
                seg = tmp;
        }
}