sysctl_binary.c

				str++;
			
			result = -EFAULT;
			if (put_user(value, vec + i))
				goto out_kfree;

			copied += sizeof(*vec);
			if (!isdigit(*str))
				break;
		}
	}

	if (newval && newlen) {
		unsigned __user *vec = newval;
		size_t length = newlen / sizeof(*vec);
		char *str, *end;
		int i;

		str = buffer;
		end = str + BUFSZ;
		for (i = 0; i < length; i++) {
			unsigned long value;

			result = -EFAULT;
			if (get_user(value, vec + i))
				goto out_kfree;

			str += snprintf(str, end - str, "%lu\t", value);
		}

		result = kernel_write(file, buffer, str - buffer, 0);
		if (result < 0)
			goto out_kfree;
	}
	result = copied;
out_kfree:
	kfree(buffer);
out:
	return result;
}

static ssize_t bin_ulongvec(struct file *file,
	void __user *oldval, size_t oldlen, void __user *newval, size_t newlen)
{
	ssize_t copied = 0;
	char *buffer;
	ssize_t result;

	result = -ENOMEM;
	buffer = kmalloc(BUFSZ, GFP_KERNEL);
	if (!buffer)
		goto out;

	if (oldval && oldlen) {
		unsigned long __user *vec = oldval;
		size_t length = oldlen / sizeof(*vec);
		char *str, *end;
		int i;

		result = kernel_read(file, 0, buffer, BUFSZ - 1);
		if (result < 0)
			goto out_kfree;

		str = buffer;
		end = str + result;
		*end++ = '\0';
		for (i = 0; i < length; i++) {
			unsigned long value;

			value = simple_strtoul(str, &str, 10);
			while (isspace(*str))
				str++;
			
			result = -EFAULT;
			if (put_user(value, vec + i))
				goto out_kfree;

			copied += sizeof(*vec);
			if (!isdigit(*str))
				break;
		}
	}

	if (newval && newlen) {
		unsigned long __user *vec = newval;
		size_t length = newlen / sizeof(*vec);
		char *str, *end;
		int i;

		str = buffer;
		end = str + BUFSZ;
		for (i = 0; i < length; i++) {
			unsigned long value;

			result = -EFAULT;
			if (get_user(value, vec + i))
				goto out_kfree;

			str += snprintf(str, end - str, "%lu\t", value);
		}

		result = kernel_write(file, buffer, str - buffer, 0);
		if (result < 0)
			goto out_kfree;
	}
	result = copied;
out_kfree:
	kfree(buffer);
out:
	return result;
}

static ssize_t bin_uuid(struct file *file,
	void __user *oldval, size_t oldlen, void __user *newval, size_t newlen)
{
	ssize_t result, copied = 0;

	/* Only supports reads */
	if (oldval && oldlen) {
		char buf[40], *str = buf;
		unsigned char uuid[16];
		int i;

		result = kernel_read(file, 0, buf, sizeof(buf) - 1);
		if (result < 0)
			goto out;

		buf[result] = '\0';

		/* Convert the uuid to from a string to binary */
		for (i = 0; i < 16; i++) {
			result = -EIO;
			if (!isxdigit(str[0]) || !isxdigit(str[1]))
				goto out;

			uuid[i] = (hex_to_bin(str[0]) << 4) |
					hex_to_bin(str[1]);
			str += 2;
			if (*str == '-')
				str++;
		}

		if (oldlen > 16)
			oldlen = 16;

		result = -EFAULT;
		if (copy_to_user(oldval, uuid, oldlen))
			goto out;

		copied = oldlen;
	}
	result = copied;
out:
	return result;
}

static ssize_t bin_dn_node_address(struct file *file,
	void __user *oldval, size_t oldlen, void __user *newval, size_t newlen)
{
	ssize_t result, copied = 0;

	if (oldval && oldlen) {
		char buf[15], *nodep;
		unsigned long area, node;
		__le16 dnaddr;

		result = kernel_read(file, 0, buf, sizeof(buf) - 1);
		if (result < 0)
			goto out;

		buf[result] = '\0';

		/* Convert the decnet address to binary */
		result = -EIO;
		nodep = strchr(buf, '.');
		if (!nodep)
			goto out;
		++nodep;

		area = simple_strtoul(buf, NULL, 10);
		node = simple_strtoul(nodep, NULL, 10);

		result = -EIO;
		if ((area > 63)||(node > 1023))
			goto out;

		dnaddr = cpu_to_le16((area << 10) | node);

		result = -EFAULT;
		if (put_user(dnaddr, (__le16 __user *)oldval))
			goto out;

		copied = sizeof(dnaddr);
	}

	if (newval && newlen) {
		__le16 dnaddr;
		char buf[15];
		int len;

		result = -EINVAL;
		if (newlen != sizeof(dnaddr))
			goto out;

		result = -EFAULT;
		if (get_user(dnaddr, (__le16 __user *)newval))
			goto out;

		len = snprintf(buf, sizeof(buf), "%hu.%hu",
				le16_to_cpu(dnaddr) >> 10,
				le16_to_cpu(dnaddr) & 0x3ff);

		result = kernel_write(file, buf, len, 0);
		if (result < 0)
			goto out;
	}

	result = copied;
out:
	return result;
}

static const struct bin_table *get_sysctl(const int *name, int nlen, char *path)
{
	const struct bin_table *table = &bin_root_table[0];
	int ctl_name;

	/* The binary sysctl tables have a small maximum depth so
	 * there is no danger of overflowing our path as it PATH_MAX
	 * bytes long.
	 */
	memcpy(path, "sys/", 4);
	path += 4;

repeat:
	if (!nlen)
		return ERR_PTR(-ENOTDIR);
	ctl_name = *name;
	name++;
	nlen--;
	for ( ; table->convert; table++) {
		int len = 0;

		/*
		 * For a wild card entry map from ifindex to network
		 * device name.
		 */
		if (!table->ctl_name) {
#ifdef CONFIG_NET
			struct net *net = current->nsproxy->net_ns;
			struct net_device *dev;
			dev = dev_get_by_index(net, ctl_name);
			if (dev) {
				len = strlen(dev->name);
				memcpy(path, dev->name, len);
				dev_put(dev);
			}
#endif
		/* Use the well known sysctl number to proc name mapping */
		} else if (ctl_name == table->ctl_name) {
			len = strlen(table->procname);
			memcpy(path, table->procname, len);
		}
		if (len) {
			path += len;
			if (table->child) {
				*path++ = '/';
				table = table->child;
				goto repeat;
			}
			*path = '\0';
			return table;
		}
	}
	return ERR_PTR(-ENOTDIR);
}

static char *sysctl_getname(const int *name, int nlen, const struct bin_table **tablep)
{
	char *tmp, *result;

	result = ERR_PTR(-ENOMEM);
	tmp = __getname();
	if (tmp) {
		const struct bin_table *table = get_sysctl(name, nlen, tmp);
		result = tmp;
		*tablep = table;
		if (IS_ERR(table)) {
			__putname(tmp);
			result = ERR_CAST(table);
		}
	}
	return result;
}

static ssize_t binary_sysctl(const int *name, int nlen,
	void __user *oldval, size_t oldlen, void __user *newval, size_t newlen)
{
	const struct bin_table *table = NULL;
	struct vfsmount *mnt;
	struct file *file;
	ssize_t result;
	char *pathname;
	int flags;

	pathname = sysctl_getname(name, nlen, &table);
	result = PTR_ERR(pathname);
	if (IS_ERR(pathname))
		goto out;

	/* How should the sysctl be accessed? */
	if (oldval && oldlen && newval && newlen) {
		flags = O_RDWR;
	} else if (newval && newlen) {
		flags = O_WRONLY;
	} else if (oldval && oldlen) {
		flags = O_RDONLY;
	} else {
		result = 0;
		goto out_putname;
	}

	mnt = task_active_pid_ns(current)->proc_mnt;
	file = file_open_root(mnt->mnt_root, mnt, pathname, flags);
	result = PTR_ERR(file);
	if (IS_ERR(file))
		goto out_putname;

	result = table->convert(file, oldval, oldlen, newval, newlen);

	fput(file);
out_putname:
	__putname(pathname);
out:
	return result;
}


#else /* CONFIG_SYSCTL_SYSCALL */

static ssize_t binary_sysctl(const int *name, int nlen,
	void __user *oldval, size_t oldlen, void __user *newval, size_t newlen)
{
	return -ENOSYS;
}

#endif /* CONFIG_SYSCTL_SYSCALL */


static void deprecated_sysctl_warning(const int *name, int nlen)
{
	int i;

	/*
	 * CTL_KERN/KERN_VERSION is used by older glibc and cannot
	 * ever go away.
	 */
	if (name[0] == CTL_KERN && name[1] == KERN_VERSION)
		return;

	if (printk_ratelimit()) {
		printk(KERN_INFO
			"warning: process `%s' used the deprecated sysctl "
			"system call with ", current->comm);
		for (i = 0; i < nlen; i++)
			printk("%d.", name[i]);
		printk("\n");
	}
	return;
}

#define WARN_ONCE_HASH_BITS 8
#define WARN_ONCE_HASH_SIZE (1<<WARN_ONCE_HASH_BITS)

static DECLARE_BITMAP(warn_once_bitmap, WARN_ONCE_HASH_SIZE);

#define FNV32_OFFSET 2166136261U
#define FNV32_PRIME 0x01000193

/*
 * Print each legacy sysctl (approximately) only once.
 * To avoid making the tables non-const use a external
 * hash-table instead.
 * Worst case hash collision: 6, but very rarely.
 * NOTE! We don't use the SMP-safe bit tests. We simply
 * don't care enough.
 */
static void warn_on_bintable(const int *name, int nlen)
{
	int i;
	u32 hash = FNV32_OFFSET;

	for (i = 0; i < nlen; i++)
		hash = (hash ^ name[i]) * FNV32_PRIME;
	hash %= WARN_ONCE_HASH_SIZE;
	if (__test_and_set_bit(hash, warn_once_bitmap))
		return;
	deprecated_sysctl_warning(name, nlen);
}

static ssize_t do_sysctl(int __user *args_name, int nlen,
	void __user *oldval, size_t oldlen, void __user *newval, size_t newlen)
{
	int name[CTL_MAXNAME];
	int i;

	/* Check args->nlen. */
	if (nlen < 0 || nlen > CTL_MAXNAME)
		return -ENOTDIR;
	/* Read in the sysctl name for simplicity */
	for (i = 0; i < nlen; i++)
		if (get_user(name[i], args_name + i))
			return -EFAULT;

	warn_on_bintable(name, nlen);

	return binary_sysctl(name, nlen, oldval, oldlen, newval, newlen);
}

SYSCALL_DEFINE1(sysctl, struct __sysctl_args __user *, args)
{
	struct __sysctl_args tmp;
	size_t oldlen = 0;
	ssize_t result;

	if (copy_from_user(&tmp, args, sizeof(tmp)))
		return -EFAULT;

	if (tmp.oldval && !tmp.oldlenp)
		return -EFAULT;

	if (tmp.oldlenp && get_user(oldlen, tmp.oldlenp))
		return -EFAULT;

	result = do_sysctl(tmp.name, tmp.nlen, tmp.oldval, oldlen,
			   tmp.newval, tmp.newlen);

	if (result >= 0) {
		oldlen = result;
		result = 0;
	}

	if (tmp.oldlenp && put_user(oldlen, tmp.oldlenp))
		return -EFAULT;

	return result;
}


#ifdef CONFIG_COMPAT

struct compat_sysctl_args {
	compat_uptr_t	name;
	int		nlen;
	compat_uptr_t	oldval;
	compat_uptr_t	oldlenp;
	compat_uptr_t	newval;
	compat_size_t	newlen;
	compat_ulong_t	__unused[4];
};

COMPAT_SYSCALL_DEFINE1(sysctl, struct compat_sysctl_args __user *, args)
{
	struct compat_sysctl_args tmp;
	compat_size_t __user *compat_oldlenp;
	size_t oldlen = 0;
	ssize_t result;

	if (copy_from_user(&tmp, args, sizeof(tmp)))
		return -EFAULT;

	if (tmp.oldval && !tmp.oldlenp)
		return -EFAULT;

	compat_oldlenp = compat_ptr(tmp.oldlenp);
	if (compat_oldlenp && get_user(oldlen, compat_oldlenp))
		return -EFAULT;

	result = do_sysctl(compat_ptr(tmp.name), tmp.nlen,
			   compat_ptr(tmp.oldval), oldlen,
			   compat_ptr(tmp.newval), tmp.newlen);

	if (result >= 0) {
		oldlen = result;
		result = 0;
	}

	if (compat_oldlenp && put_user(oldlen, compat_oldlenp))
		return -EFAULT;

	return result;
}

#endif /* CONFIG_COMPAT */