drivers/staging/lustre/lustre/libcfs/linux/linux-curproc.c - kernel/lockdown - Git at Google

 /*
  * 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;
 }

 /* 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));
 }

 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 successfully transferred */
 	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;

 	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) {
 		kfree(buffer);
 		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_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);

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

	/* 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));
	}

	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 successfully transferred */
	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;

	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) {
	kfree(buffer);
	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_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);

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