include/linux/random.h


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/*
 * include/linux/random.h
 *
 * Include file for the random number generator.
 */

#ifndef _LINUX_RANDOM_H
#define _LINUX_RANDOM_H

#include <linux/types.h>
#include <linux/ioctl.h>
#include <linux/irqnr.h>

/* ioctl()'s for the random number generator */

/* Get the entropy count. */
#define RNDGETENTCNT	_IOR( 'R', 0x00, int )

/* Add to (or subtract from) the entropy count.  (Superuser only.) */
#define RNDADDTOENTCNT	_IOW( 'R', 0x01, int )

/* Get the contents of the entropy pool.  (Superuser only.) */
#define RNDGETPOOL	_IOR( 'R', 0x02, int [2] )

/* 
 * Write bytes into the entropy pool and add to the entropy count.
 * (Superuser only.)
 */
#define RNDADDENTROPY	_IOW( 'R', 0x03, int [2] )

/* Clear entropy count to 0.  (Superuser only.) */
#define RNDZAPENTCNT	_IO( 'R', 0x04 )

/* Clear the entropy pool and associated counters.  (Superuser only.) */
#define RNDCLEARPOOL	_IO( 'R', 0x06 )

struct rand_pool_info {
	int	entropy_count;
	int	buf_size;
	__u32	buf[0];
};

/* Exported functions */

#ifdef __KERNEL__

extern void rand_initialize_irq(int irq);

extern void add_input_randomness(unsigned int type, unsigned int code,
				 unsigned int value);
extern void add_interrupt_randomness(int irq);

extern void get_random_bytes(void *buf, int nbytes);
void generate_random_uuid(unsigned char uuid_out[16]);

extern __u32 secure_ip_id(__be32 daddr);
extern u32 secure_ipv4_port_ephemeral(__be32 saddr, __be32 daddr, __be16 dport);
extern u32 secure_ipv6_port_ephemeral(const __be32 *saddr, const __be32 *daddr,
				      __be16 dport);
extern __u32 secure_tcp_sequence_number(__be32 saddr, __be32 daddr,
					__be16 sport, __be16 dport);
extern __u32 secure_tcpv6_sequence_number(__be32 *saddr, __be32 *daddr,
					  __be16 sport, __be16 dport);
extern u64 secure_dccp_sequence_number(__be32 saddr, __be32 daddr,
				       __be16 sport, __be16 dport);

#ifndef MODULE
extern const struct file_operations random_fops, urandom_fops;
#endif

unsigned int get_random_int(void);
unsigned long randomize_range(unsigned long start, unsigned long end, unsigned long len);

u32 random32(void);
void srandom32(u32 seed);

#endif /* __KERNEL___ */

#endif /* _LINUX_RANDOM_H */
/*
 *  linux/fs/read_write.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

#include <linux/slab.h> 
#include <linux/stat.h>
#include <linux/fcntl.h>
#include <linux/file.h>
#include <linux/uio.h>
#include <linux/smp_lock.h>
#include <linux/fsnotify.h>
#include <linux/security.h>
#include <linux/module.h>
#include <linux/syscalls.h>

#include <asm/uaccess.h>
#include <asm/unistd.h>

struct file_operations generic_ro_fops = {
	.llseek		= generic_file_llseek,
	.read		= generic_file_read,
	.mmap		= generic_file_readonly_mmap,
	.sendfile	= generic_file_sendfile,
};

EXPORT_SYMBOL(generic_ro_fops);

loff_t generic_file_llseek(struct file *file, loff_t offset, int origin)
{
	long long retval;
	struct inode *inode = file->f_mapping->host;

	down(&inode->i_sem);
	switch (origin) {
		case 2:
			offset += inode->i_size;
			break;
		case 1:
			offset += file->f_pos;
	}
	retval = -EINVAL;
	if (offset>=0 && offset<=inode->i_sb->s_maxbytes) {
		if (offset != file->f_pos) {
			file->f_pos = offset;
			file->f_version = 0;
		}
		retval = offset;
	}
	up(&inode->i_sem);
	return retval;
}

EXPORT_SYMBOL(generic_file_llseek);

loff_t remote_llseek(struct file *file, loff_t offset, int origin)
{
	long long retval;

	lock_kernel();
	switch (origin) {
		case 2:
			offset += i_size_read(file->f_dentry->d_inode);
			break;
		case 1:
			offset += file->f_pos;
	}
	retval = -EINVAL;
	if (offset>=0 && offset<=file->f_dentry->d_inode->i_sb->s_maxbytes) {
		if (offset != file->f_pos) {
			file->f_pos = offset;
			file->f_version = 0;
		}
		retval = offset;
	}
	unlock_kernel();
	return retval;
}
EXPORT_SYMBOL(remote_llseek);

loff_t no_llseek(struct file *file, loff_t offset, int origin)
{
	return -ESPIPE;
}
EXPORT_SYMBOL(no_llseek);

loff_t default_llseek(struct file *file, loff_t offset, int origin)
{
	long long retval;

	lock_kernel();
	switch (origin) {
		case 2:
			offset += i_size_read(file->f_dentry->d_inode);
			break;
		case 1:
			offset += file->f_pos;
	}
	retval = -EINVAL;
	if (offset >= 0) {
		if (offset != file->f_pos) {
			file->f_pos = offset;
			file->f_version = 0;
		}
		retval = offset;
	}
	unlock_kernel();
	return retval;
}
EXPORT_SYMBOL(default_llseek);

loff_t vfs_llseek(struct file *file, loff_t offset, int origin)
{
	loff_t (*fn)(struct file *, loff_t, int);

	fn = no_llseek;
	if (file->f_mode & FMODE_LSEEK) {
		fn = default_llseek;
		if (file->f_op && file->f_op->llseek)
			fn = file->f_op->llseek;
	}
	return fn(file, offset, origin);
}
EXPORT_SYMBOL(vfs_llseek);

asmlinkage off_t sys_lseek(unsigned int fd, off_t offset, unsigned int origin)
{
	off_t retval;
	struct file * file;
	int fput_needed;

	retval = -EBADF;
	file = fget_light(fd, &fput_needed);
	if (!file)
		goto bad;

	retval = -EINVAL;
	if (origin <= 2) {
		loff_t res = vfs_llseek(file, offset, origin);
		retval = res;
		if (res != (loff_t)retval)
			retval = -EOVERFLOW;	/* LFS: should only happen on 32 bit platforms */
	}
	fput_light(file, fput_needed);
bad:
	return retval;
}

#ifdef __ARCH_WANT_SYS_LLSEEK
asmlinkage long sys_llseek(unsigned int fd, unsigned long offset_high,
			   unsigned long offset_low, loff_t __user * result,
			   unsigned int origin)
{
	int retval;
	struct file * file;
	loff_t offset;
	int fput_needed;

	retval = -EBADF;
	file = fget_light(fd, &fput_needed);
	if (!file)
		goto bad;

	retval = -EINVAL;
	if (origin > 2)
		goto out_putf;

	offset = vfs_llseek(file, ((loff_t) offset_high << 32) | offset_low,
			origin);

	retval = (int)offset;
	if (offset >= 0) {
		retval = -EFAULT;
		if (!copy_to_user(result, &offset, sizeof(offset)))
			retval = 0;
	}
out_putf:
	fput_light(file, fput_needed);
bad:
	return retval;
}
#endif


int rw_verify_area(int read_write, struct file *file, loff_t *ppos, size_t count)
{
	struct inode *inode;
	loff_t pos;

	if (unlikely(count > INT_MAX))
		goto Einval;
	pos = *ppos;
	if (unlikely((pos < 0) || (loff_t) (pos + count) < 0))
		goto Einval;

	inode = file->f_dentry->d_inode;
	if (inode->i_flock && MANDATORY_LOCK(inode))
		return locks_mandatory_area(read_write == READ ? FLOCK_VERIFY_READ : FLOCK_VERIFY_WRITE, inode, file, pos, count);
	return 0;

Einval:
	return -EINVAL;
}

static void wait_on_retry_sync_kiocb(struct kiocb *iocb)
{
	set_current_state(TASK_UNINTERRUPTIBLE);
	if (!kiocbIsKicked(iocb))
		schedule();
	else
		kiocbClearKicked(iocb);
	__set_current_state(TASK_RUNNING);
}

ssize_t do_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos)
{
	struct kiocb kiocb;
	ssize_t ret;

	init_sync_kiocb(&kiocb, filp);
	kiocb.ki_pos = *ppos;
	while (-EIOCBRETRY ==
		(ret = filp->f_op->aio_read(&kiocb, buf, len, kiocb.ki_pos)))
		wait_on_retry_sync_kiocb(&kiocb);

	if (-EIOCBQUEUED == ret)
		ret = wait_on_sync_kiocb(&kiocb);
	*ppos = kiocb.ki_pos;
	return ret;
}

EXPORT_SYMBOL(do_sync_read);

ssize_t vfs_read(struct file *file, char __user *buf, size_t count, loff_t *pos)
{
	ssize_t ret;

	if (!(file->f_mode & FMODE_READ))
		return -EBADF;
	if (!file->f_op || (!file->f_op->read && !file->f_op->aio_read))
		return -EINVAL;
	if (unlikely(!access_ok(VERIFY_WRITE, buf, count)))
		return -EFAULT;

	ret = rw_verify_area(READ, file, pos, count);
	if (!ret) {
		ret = security_file_permission (file, MAY_READ);
		if (!ret) {
			if (file->f_op->read)
				ret = file->f_op->read(file, buf, count, pos);
			else
				ret = do_sync_read(file, buf, count, pos);
			if (ret > 0) {
				fsnotify_access(file->f_dentry);
				current->rchar += ret;
			}
			current->syscr++;
		}
	}

	return ret;
}

EXPORT_SYMBOL(vfs_read);

ssize_t do_sync_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos)
{
	struct kiocb kiocb;
	ssize_t ret;

	init_sync_kiocb(&kiocb, filp);
	kiocb.ki_pos = *ppos;
	while (-EIOCBRETRY ==
	       (ret = filp->f_op->aio_write(&kiocb, buf, len, kiocb.ki_pos)))
		wait_on_retry_sync_kiocb(&kiocb);

	if (-EIOCBQUEUED == ret)
		ret = wait_on_sync_kiocb(&kiocb);
	*ppos = kiocb.ki_pos;
	return ret;
}

EXPORT_SYMBOL(do_sync_write);

ssize_t vfs_write(struct file *file, const char __user *buf, size_t count, loff_t *pos)
{
	ssize_t ret;

	if (!(file->f_mode & FMODE_WRITE))
		return -EBADF;
	if (!file->f_op || (!file->f_op->write && !file->f_op->aio_write))
		return -EINVAL;
	if (unlikely(!access_ok(VERIFY_READ, buf, count)))
		return -EFAULT;

	ret = rw_verify_area(WRITE, file, pos, count);
	if (!ret) {
		ret = security_file_permission (file, MAY_WRITE);
		if (!ret) {
			if (file->f_op->write)
				ret = file->f_op->write(file, buf, count, pos);
			else
				ret = do_sync_write(file, buf, count, pos);
			if (ret > 0) {
				fsnotify_modify(file->f_dentry);
				current->wchar += ret;
			}
			current->syscw++;
		}
	}

	return ret;
}

EXPORT_SYMBOL(vfs_write);

static inline loff_t file_pos_read(struct file *file)
{
	return file->f_pos;
}

static inline void file_pos_write(struct file *file, loff_t pos)
{
	file->f_pos = pos;
}

asmlinkage ssize_t sys_read(unsigned int fd, char __user * buf, size_t count)
{
	struct file *file;
	ssize_t ret = -EBADF;
	int fput_needed;

	file = fget_light(fd, &fput_needed);
	if (file) {
		loff_t pos = file_pos_read(file);
		ret = vfs_read(file, buf, count, &pos);
		file_pos_write(file, pos);
		fput_light(file, fput_needed);
	}

	return ret;
}
EXPORT_SYMBOL_GPL(sys_read);

asmlinkage ssize_t sys_write(unsigned int fd, const char __user * buf, size_t count)
{
	struct file *file;
	ssize_t ret = -EBADF;
	int fput_needed;

	file = fget_light(fd, &fput_needed);
	if (file) {
		loff_t pos = file_pos_read(file);
		ret = vfs_write(file, buf, count, &pos);
		file_pos_write(file, pos);
		fput_light(file, fput_needed);
	}

	return ret;
}

asmlinkage ssize_t sys_pread64(unsigned int fd, char __user *buf,
			     size_t count, loff_t pos)
{
	struct file *file;
	ssize_t ret = -EBADF;
	int fput_needed;

	if (pos < 0)
		return -EINVAL;

	file = fget_light(fd, &fput_needed);
	if (file) {
		ret = -ESPIPE;
		if (file->f_mode & FMODE_PREAD)
			ret = vfs_read(file, buf, count, &pos);
		fput_light(file, fput_needed);
	}

	return ret;
}

asmlinkage ssize_t sys_pwrite64(unsigned int fd, const char __user *buf,
			      size_t count, loff_t pos)
{
	struct file *file;
	ssize_t ret = -EBADF;
	int fput_needed;

	if (pos < 0)
		return -EINVAL;

	file = fget_light(fd, &fput_needed);
	if (file) {
		ret = -ESPIPE;
		if (file->f_mode & FMODE_PWRITE)  
			ret = vfs_write(file, buf, count, &pos);
		fput_light(file, fput_needed);
	}

	return ret;
}

/*
 * Reduce an iovec's length in-place.  Return the resulting number of segments
 */
unsigned long iov_shorten(struct iovec *iov, unsigned long nr_segs, size_t to)
{
	unsigned long seg = 0;
	size_t len = 0;

	while (seg < nr_segs) {
		seg++;
		if (len + iov->iov_len >= to) {
			iov->iov_len = to - len;
			break;
		}
		len += iov->iov_len;
		iov++;
	}
	return seg;
}

EXPORT_SYMBOL(iov_shorten);

/* A write operation does a read from user space and vice versa */
#define vrfy_dir(type) ((type) == READ ? VERIFY_WRITE : VERIFY_READ)

static ssize_t do_readv_writev(int type, struct file *file,
			       const struct iovec __user * uvector,
			       unsigned long nr_segs, loff_t *pos)
{
	typedef ssize_t (*io_fn_t)(struct file *, char __user *, size_t, loff_t *);
	typedef ssize_t (*iov_fn_t)(struct file *, const struct iovec *, unsigned long, loff_t *);

	size_t tot_len;
	struct iovec iovstack[UIO_FASTIOV];
	struct iovec *iov=iovstack, *vector;
	ssize_t ret;
	int seg;
	io_fn_t fn;
	iov_fn_t fnv;

	/*
	 * SuS says "The readv() function *may* fail if the iovcnt argument
	 * was less than or equal to 0, or greater than {IOV_MAX}.  Linux has
	 * traditionally returned zero for zero segments, so...
	 */
	ret = 0;
	if (nr_segs == 0)
		goto out;

	/*
	 * First get the "struct iovec" from user memory and
	 * verify all the pointers
	 */
	ret = -EINVAL;
	if ((nr_segs > UIO_MAXIOV) || (nr_segs <= 0))
		goto out;
	if (!file->f_op)
		goto out;
	if (nr_segs > UIO_FASTIOV) {
		ret = -ENOMEM;
		iov = kmalloc(nr_segs*sizeof(struct iovec), GFP_KERNEL);
		if (!iov)
			goto out;
	}
	ret = -EFAULT;
	if (copy_from_user(iov, uvector, nr_segs*sizeof(*uvector)))
		goto out;

	/*
	 * Single unix specification:
	 * We should -EINVAL if an element length is not >= 0 and fitting an
	 * ssize_t.  The total length is fitting an ssize_t
	 *
	 * Be careful here because iov_len is a size_t not an ssize_t
	 */
	tot_len = 0;
	ret = -EINVAL;
	for (seg = 0; seg < nr_segs; seg++) {
		void __user *buf = iov[seg].iov_base;
		ssize_t len = (ssize_t)iov[seg].iov_len;

		if (len < 0)	/* size_t not fitting an ssize_t .. */
			goto out;