/*
 * GPL HEADER START
 *
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 only,
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License version 2 for more details (a copy is included
 * in the LICENSE file that accompanied this code).
 *
 * You should have received a copy of the GNU General Public License
 * version 2 along with this program; If not, see
 * http://www.sun.com/software/products/lustre/docs/GPLv2.pdf
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 *
 * GPL HEADER END
 */
/*
 * Copyright (c) 2008, 2010, Oracle and/or its affiliates. All rights reserved.
 * Use is subject to license terms.
 *
 * Copyright (c) 2011, 2012, Intel Corporation.
 */
/*
 * This file is part of Lustre, http://www.lustre.org/
 * Lustre is a trademark of Sun Microsystems, Inc.
 *
 * libcfs/libcfs/linux/linux-curproc.c
 *
 * Lustre curproc API implementation for Linux kernel
 *
 * Author: Nikita Danilov <nikita@clusterfs.com>
 */

#include <linux/sched.h>
#include <linux/fs_struct.h>

#include <linux/compat.h>
#include <linux/thread_info.h>

#define DEBUG_SUBSYSTEM S_LNET

#include <linux/libcfs/libcfs.h>

/*
 * Implementation of cfs_curproc API (see portals/include/libcfs/curproc.h)
 * for Linux kernel.
 */

int    cfs_curproc_groups_nr(void)
{
        int nr;

        task_lock(current);
        nr = current_cred()->group_info->ngroups;
        task_unlock(current);
        return nr;
}

void   cfs_curproc_groups_dump(gid_t *array, int size)
{
        task_lock(current);
        size = min_t(int, size, current_cred()->group_info->ngroups);
        memcpy(array, current_cred()->group_info->blocks[0], size * sizeof(__u32));
        task_unlock(current);
}


int    current_is_in_group(gid_t gid)
{
        return in_group_p(gid);
}

/* Currently all the CFS_CAP_* defines match CAP_* ones. */
#define cfs_cap_pack(cap) (cap)
#define cfs_cap_unpack(cap) (cap)

void cfs_cap_raise(cfs_cap_t cap)
{
        struct cred *cred;
        if ((cred = prepare_creds())) {
                cap_raise(cred->cap_effective, cfs_cap_unpack(cap));
                commit_creds(cred);
        }
}

void cfs_cap_lower(cfs_cap_t cap)
{
        struct cred *cred;
        if ((cred = prepare_creds())) {
                cap_lower(cred->cap_effective, cfs_cap_unpack(cap));
                commit_creds(cred);
        }
}

int cfs_cap_raised(cfs_cap_t cap)
{
        return cap_raised(current_cap(), cfs_cap_unpack(cap));
}

void cfs_kernel_cap_pack(kernel_cap_t kcap, cfs_cap_t *cap)
{
#if defined (_LINUX_CAPABILITY_VERSION) && _LINUX_CAPABILITY_VERSION == 0x19980330
        *cap = cfs_cap_pack(kcap);
#elif defined (_LINUX_CAPABILITY_VERSION) && _LINUX_CAPABILITY_VERSION == 0x20071026
        *cap = cfs_cap_pack(kcap[0]);
#elif defined(_KERNEL_CAPABILITY_VERSION) && _KERNEL_CAPABILITY_VERSION == 0x20080522
        /* XXX lost high byte */
        *cap = cfs_cap_pack(kcap.cap[0]);
#else
        #error "need correct _KERNEL_CAPABILITY_VERSION "
#endif
}

void cfs_kernel_cap_unpack(kernel_cap_t *kcap, cfs_cap_t cap)
{
#if defined (_LINUX_CAPABILITY_VERSION) && _LINUX_CAPABILITY_VERSION == 0x19980330
        *kcap = cfs_cap_unpack(cap);
#elif defined (_LINUX_CAPABILITY_VERSION) && _LINUX_CAPABILITY_VERSION == 0x20071026
        (*kcap)[0] = cfs_cap_unpack(cap);
#elif defined(_KERNEL_CAPABILITY_VERSION) && _KERNEL_CAPABILITY_VERSION == 0x20080522
        kcap->cap[0] = cfs_cap_unpack(cap);
#else
        #error "need correct _KERNEL_CAPABILITY_VERSION "
#endif
}

cfs_cap_t cfs_curproc_cap_pack(void)
{
        cfs_cap_t cap;
        cfs_kernel_cap_pack(current_cap(), &cap);
        return cap;
}

void cfs_curproc_cap_unpack(cfs_cap_t cap)
{
        struct cred *cred;
        if ((cred = prepare_creds())) {
                cfs_kernel_cap_unpack(&cred->cap_effective, cap);
                commit_creds(cred);
        }
}

int cfs_capable(cfs_cap_t cap)
{
        return capable(cfs_cap_unpack(cap));
}

/* Check if task is running in 32-bit API mode, for the purpose of
 * userspace binary interfaces.  On 32-bit Linux this is (unfortunately)
 * always true, even if the application is using LARGEFILE64 and 64-bit
 * APIs, because Linux provides no way for the filesystem to know if it
 * is called via 32-bit or 64-bit APIs.  Other clients may vary.  On
 * 64-bit systems, this will only be true if the binary is calling a
 * 32-bit system call. */
int current_is_32bit(void)
{
        return is_compat_task();
}

static int cfs_access_process_vm(struct task_struct *tsk, unsigned long addr,
                                 void *buf, int len, int write)
{
        /* Just copied from kernel for the kernels which doesn't
         * have access_process_vm() exported */
        struct mm_struct *mm;
        struct vm_area_struct *vma;
        struct page *page;
        void *old_buf = buf;

        mm = get_task_mm(tsk);
        if (!mm)
                return 0;

        down_read(&mm->mmap_sem);
        /* ignore errors, just check how much was sucessfully transfered */
        while (len) {
                int bytes, rc, offset;
                void *maddr;

                rc = get_user_pages(tsk, mm, addr, 1,
                                     write, 1, &page, &vma);
                if (rc <= 0)
                        break;

                bytes = len;
                offset = addr & (PAGE_SIZE-1);
                if (bytes > PAGE_SIZE-offset)
                        bytes = PAGE_SIZE-offset;

                maddr = kmap(page);
                if (write) {
                        copy_to_user_page(vma, page, addr,
                                          maddr + offset, buf, bytes);
                        set_page_dirty_lock(page);
                } else {
                        copy_from_user_page(vma, page, addr,
                                            buf, maddr + offset, bytes);
                }
                kunmap(page);
                page_cache_release(page);
                len -= bytes;
                buf += bytes;
                addr += bytes;
        }
        up_read(&mm->mmap_sem);
        mmput(mm);

        return buf - old_buf;
}

/* Read the environment variable of current process specified by @key. */
int cfs_get_environ(const char *key, char *value, int *val_len)
{
        struct mm_struct *mm;
        char *buffer, *tmp_buf = NULL;
        int buf_len = PAGE_CACHE_SIZE;
        int key_len = strlen(key);
        unsigned long addr;
        int rc;
        ENTRY;

        buffer = kmalloc(buf_len, GFP_USER);
        if (!buffer)
                RETURN(-ENOMEM);

        mm = get_task_mm(current);
        if (!mm) {
                kfree(buffer);
                RETURN(-EINVAL);
        }

        /* Avoid deadlocks on mmap_sem if called from sys_mmap_pgoff(),
         * which is already holding mmap_sem for writes.  If some other
         * thread gets the write lock in the meantime, this thread will
         * block, but at least it won't deadlock on itself.  LU-1735 */
        if (down_read_trylock(&mm->mmap_sem) == 0)
                return -EDEADLK;
        up_read(&mm->mmap_sem);

        addr = mm->env_start;
        while (addr < mm->env_end) {
                int this_len, retval, scan_len;
                char *env_start, *env_end;

                memset(buffer, 0, buf_len);

                this_len = min_t(int, mm->env_end - addr, buf_len);
                retval = cfs_access_process_vm(current, addr, buffer,
                                               this_len, 0);
                if (retval != this_len)
                        break;

                addr += retval;

                /* Parse the buffer to find out the specified key/value pair.
                 * The "key=value" entries are separated by '\0'. */
                env_start = buffer;
                scan_len = this_len;
                while (scan_len) {
                        char *entry;
                        int entry_len;

                        env_end = memscan(env_start, '\0', scan_len);
                        LASSERT(env_end >= env_start &&
                                env_end <= env_start + scan_len);

                        /* The last entry of this buffer cross the buffer
                         * boundary, reread it in next cycle. */
                        if (unlikely(env_end - env_start == scan_len)) {
                                /* This entry is too large to fit in buffer */
                                if (unlikely(scan_len == this_len)) {
                                        CERROR("Too long env variable.\n");
                                        GOTO(out, rc = -EINVAL);
                                }
                                addr -= scan_len;
                                break;
                        }

                        entry = env_start;
                        entry_len = env_end - env_start;

                        /* Key length + length of '=' */
                        if (entry_len > key_len + 1 &&
                            !memcmp(entry, key, key_len)) {
                                entry += key_len + 1;
                                entry_len -= key_len + 1;
                                /* The 'value' buffer passed in is too small.*/
                                if (entry_len >= *val_len)
                                        GOTO(out, rc = -EOVERFLOW);

                                memcpy(value, entry, entry_len);
                                *val_len = entry_len;
                                GOTO(out, rc = 0);
                        }

                        scan_len -= (env_end - env_start + 1);
                        env_start = env_end + 1;
                }
        }
        GOTO(out, rc = -ENOENT);

out:
        mmput(mm);
        kfree((void *)buffer);
        if (tmp_buf)
                kfree((void *)tmp_buf);
        return rc;
}
EXPORT_SYMBOL(cfs_get_environ);

EXPORT_SYMBOL(cfs_curproc_groups_nr);
EXPORT_SYMBOL(cfs_curproc_groups_dump);
EXPORT_SYMBOL(current_is_in_group);
EXPORT_SYMBOL(cfs_cap_raise);
EXPORT_SYMBOL(cfs_cap_lower);
EXPORT_SYMBOL(cfs_cap_raised);
EXPORT_SYMBOL(cfs_curproc_cap_pack);
EXPORT_SYMBOL(cfs_curproc_cap_unpack);
EXPORT_SYMBOL(cfs_capable);
EXPORT_SYMBOL(current_is_32bit);

/*
 * Local variables:
 * c-indentation-style: "K&R"
 * c-basic-offset: 8
 * tab-width: 8
 * fill-column: 80
 * scroll-step: 1
 * End:
 */