sysctl.c

linux 2.6.19 kernel source code before patching

				if (sysctl_perm(table, 001))
					return -EPERM;
				name++;
				nlen--;
				table = table->child;
				goto repeat;
			}
			error = do_sysctl_strategy(table, name, nlen,
						   oldval, oldlenp,
						   newval, newlen);
			return error;
		}
	}
	return -ENOTDIR;
}

/* Perform the actual read/write of a sysctl table entry. */
int do_sysctl_strategy (ctl_table *table, 
			int __user *name, int nlen,
			void __user *oldval, size_t __user *oldlenp,
			void __user *newval, size_t newlen)
{
	int op = 0, rc;
	size_t len;

	if (oldval)
		op |= 004;
	if (newval) 
		op |= 002;
	if (sysctl_perm(table, op))
		return -EPERM;

	if (table->strategy) {
		rc = table->strategy(table, name, nlen, oldval, oldlenp,
				     newval, newlen);
		if (rc < 0)
			return rc;
		if (rc > 0)
			return 0;
	}

	/* If there is no strategy routine, or if the strategy returns
	 * zero, proceed with automatic r/w */
	if (table->data && table->maxlen) {
		if (oldval && oldlenp) {
			if (get_user(len, oldlenp))
				return -EFAULT;
			if (len) {
				if (len > table->maxlen)
					len = table->maxlen;
				if(copy_to_user(oldval, table->data, len))
					return -EFAULT;
				if(put_user(len, oldlenp))
					return -EFAULT;
			}
		}
		if (newval && newlen) {
			len = newlen;
			if (len > table->maxlen)
				len = table->maxlen;
			if(copy_from_user(table->data, newval, len))
				return -EFAULT;
		}
	}
	return 0;
}
#endif /* CONFIG_SYSCTL_SYSCALL */

static void sysctl_set_parent(struct ctl_table *parent, struct ctl_table *table)
{
	for (; table->ctl_name || table->procname; table++) {
		table->parent = parent;
		if (table->child)
			sysctl_set_parent(table, table->child);
	}
}

static __init int sysctl_init(void)
{
	sysctl_set_parent(NULL, root_table);
	return 0;
}

core_initcall(sysctl_init);

/**
 * register_sysctl_table - register a sysctl hierarchy
 * @table: the top-level table structure
 *
 * Register a sysctl table hierarchy. @table should be a filled in ctl_table
 * array. An entry with a ctl_name of 0 terminates the table. 
 *
 * The members of the &ctl_table structure are used as follows:
 *
 * ctl_name - This is the numeric sysctl value used by sysctl(2). The number
 *            must be unique within that level of sysctl
 *
 * procname - the name of the sysctl file under /proc/sys. Set to %NULL to not
 *            enter a sysctl file
 *
 * data - a pointer to data for use by proc_handler
 *
 * maxlen - the maximum size in bytes of the data
 *
 * mode - the file permissions for the /proc/sys file, and for sysctl(2)
 *
 * child - a pointer to the child sysctl table if this entry is a directory, or
 *         %NULL.
 *
 * proc_handler - the text handler routine (described below)
 *
 * strategy - the strategy routine (described below)
 *
 * de - for internal use by the sysctl routines
 *
 * extra1, extra2 - extra pointers usable by the proc handler routines
 *
 * Leaf nodes in the sysctl tree will be represented by a single file
 * under /proc; non-leaf nodes will be represented by directories.
 *
 * sysctl(2) can automatically manage read and write requests through
 * the sysctl table.  The data and maxlen fields of the ctl_table
 * struct enable minimal validation of the values being written to be
 * performed, and the mode field allows minimal authentication.
 *
 * More sophisticated management can be enabled by the provision of a
 * strategy routine with the table entry.  This will be called before
 * any automatic read or write of the data is performed.
 *
 * The strategy routine may return
 *
 * < 0 - Error occurred (error is passed to user process)
 *
 * 0   - OK - proceed with automatic read or write.
 *
 * > 0 - OK - read or write has been done by the strategy routine, so
 *       return immediately.
 *
 * There must be a proc_handler routine for any terminal nodes
 * mirrored under /proc/sys (non-terminals are handled by a built-in
 * directory handler).  Several default handlers are available to
 * cover common cases -
 *
 * proc_dostring(), proc_dointvec(), proc_dointvec_jiffies(),
 * proc_dointvec_userhz_jiffies(), proc_dointvec_minmax(), 
 * proc_doulongvec_ms_jiffies_minmax(), proc_doulongvec_minmax()
 *
 * It is the handler's job to read the input buffer from user memory
 * and process it. The handler should return 0 on success.
 *
 * This routine returns %NULL on a failure to register, and a pointer
 * to the table header on success.
 */
struct ctl_table_header *register_sysctl_table(ctl_table * table)
{
	struct ctl_table_header *tmp;
	tmp = kmalloc(sizeof(struct ctl_table_header), GFP_KERNEL);
	if (!tmp)
		return NULL;
	tmp->ctl_table = table;
	INIT_LIST_HEAD(&tmp->ctl_entry);
	tmp->used = 0;
	tmp->unregistering = NULL;
	sysctl_set_parent(NULL, table);
	spin_lock(&sysctl_lock);
	list_add_tail(&tmp->ctl_entry, &root_table_header.ctl_entry);
	spin_unlock(&sysctl_lock);
	return tmp;
}

/**
 * unregister_sysctl_table - unregister a sysctl table hierarchy
 * @header: the header returned from register_sysctl_table
 *
 * Unregisters the sysctl table and all children. proc entries may not
 * actually be removed until they are no longer used by anyone.
 */
void unregister_sysctl_table(struct ctl_table_header * header)
{
	might_sleep();
	spin_lock(&sysctl_lock);
	start_unregistering(header);
	spin_unlock(&sysctl_lock);
	kfree(header);
}

#else /* !CONFIG_SYSCTL */
struct ctl_table_header *register_sysctl_table(ctl_table * table)
{
	return NULL;
}

void unregister_sysctl_table(struct ctl_table_header * table)
{
}

#endif /* CONFIG_SYSCTL */

/*
 * /proc/sys support
 */

#ifdef CONFIG_PROC_SYSCTL

static int _proc_do_string(void* data, int maxlen, int write,
			   struct file *filp, void __user *buffer,
			   size_t *lenp, loff_t *ppos)
{
	size_t len;
	char __user *p;
	char c;

	if (!data || !maxlen || !*lenp) {
		*lenp = 0;
		return 0;
	}

	if (write) {
		len = 0;
		p = buffer;
		while (len < *lenp) {
			if (get_user(c, p++))
				return -EFAULT;
			if (c == 0 || c == '\n')
				break;
			len++;
		}
		if (len >= maxlen)
			len = maxlen-1;
		if(copy_from_user(data, buffer, len))
			return -EFAULT;
		((char *) data)[len] = 0;
		*ppos += *lenp;
	} else {
		len = strlen(data);
		if (len > maxlen)
			len = maxlen;

		if (*ppos > len) {
			*lenp = 0;
			return 0;
		}

		data += *ppos;
		len  -= *ppos;

		if (len > *lenp)
			len = *lenp;
		if (len)
			if(copy_to_user(buffer, data, len))
				return -EFAULT;
		if (len < *lenp) {
			if(put_user('\n', ((char __user *) buffer) + len))
				return -EFAULT;
			len++;
		}
		*lenp = len;
		*ppos += len;
	}
	return 0;
}

/**
 * proc_dostring - read a string sysctl
 * @table: the sysctl table
 * @write: %TRUE if this is a write to the sysctl file
 * @filp: the file structure
 * @buffer: the user buffer
 * @lenp: the size of the user buffer
 * @ppos: file position
 *
 * Reads/writes a string from/to the user buffer. If the kernel
 * buffer provided is not large enough to hold the string, the
 * string is truncated. The copied string is %NULL-terminated.
 * If the string is being read by the user process, it is copied
 * and a newline '\n' is added. It is truncated if the buffer is
 * not large enough.
 *
 * Returns 0 on success.
 */
int proc_dostring(ctl_table *table, int write, struct file *filp,
		  void __user *buffer, size_t *lenp, loff_t *ppos)
{
	return _proc_do_string(table->data, table->maxlen, write, filp,
			       buffer, lenp, ppos);
}


static int do_proc_dointvec_conv(int *negp, unsigned long *lvalp,
				 int *valp,
				 int write, void *data)
{
	if (write) {
		*valp = *negp ? -*lvalp : *lvalp;
	} else {
		int val = *valp;
		if (val < 0) {
			*negp = -1;
			*lvalp = (unsigned long)-val;
		} else {
			*negp = 0;
			*lvalp = (unsigned long)val;
		}
	}
	return 0;
}

static int __do_proc_dointvec(void *tbl_data, ctl_table *table,
		  int write, struct file *filp, void __user *buffer,
		  size_t *lenp, loff_t *ppos,
		  int (*conv)(int *negp, unsigned long *lvalp, int *valp,
			      int write, void *data),
		  void *data)
{
#define TMPBUFLEN 21
	int *i, vleft, first=1, neg, val;
	unsigned long lval;
	size_t left, len;
	
	char buf[TMPBUFLEN], *p;
	char __user *s = buffer;
	
	if (!tbl_data || !table->maxlen || !*lenp ||
	    (*ppos && !write)) {
		*lenp = 0;
		return 0;
	}
	
	i = (int *) tbl_data;
	vleft = table->maxlen / sizeof(*i);
	left = *lenp;

	if (!conv)
		conv = do_proc_dointvec_conv;

	for (; left && vleft--; i++, first=0) {
		if (write) {
			while (left) {
				char c;
				if (get_user(c, s))
					return -EFAULT;
				if (!isspace(c))
					break;
				left--;
				s++;
			}
			if (!left)
				break;
			neg = 0;
			len = left;
			if (len > sizeof(buf) - 1)
				len = sizeof(buf) - 1;
			if (copy_from_user(buf, s, len))
				return -EFAULT;
			buf[len] = 0;
			p = buf;
			if (*p == '-' && left > 1) {
				neg = 1;
				p++;
			}
			if (*p < '0' || *p > '9')
				break;

			lval = simple_strtoul(p, &p, 0);

			len = p-buf;
			if ((len < left) && *p && !isspace(*p))
				break;
			if (neg)
				val = -val;
			s += len;
			left -= len;

			if (conv(&neg, &lval, i, 1, data))
				break;
		} else {
			p = buf;
			if (!first)
				*p++ = '\t';
	
			if (conv(&neg, &lval, i, 0, data))
				break;

			sprintf(p, "%s%lu", neg ? "-" : "", lval);
			len = strlen(buf);
			if (len > left)
				len = left;
			if(copy_to_user(s, buf, len))
				return -EFAULT;
			left -= len;
			s += len;
		}
	}

	if (!write && !first && left) {
		if(put_user('\n', s))
			return -EFAULT;
		left--, s++;
	}
	if (write) {
		while (left) {
			char c;
			if (get_user(c, s++))
				return -EFAULT;
			if (!isspace(c))
				break;
			left--;
		}
	}
	if (write && first)
		return -EINVAL;
	*lenp -= left;
	*ppos += *lenp;
	return 0;
#undef TMPBUFLEN
}

static int do_proc_dointvec(ctl_table *table, int write, struct file *filp,
		  void __user *buffer, size_t *lenp, loff_t *ppos,
		  int (*conv)(int *negp, unsigned long *lvalp, int *valp,
			      int write, void *data),
		  void *data)
{
	return __do_proc_dointvec(table->data, table, write, filp,
			buffer, lenp, ppos, conv, data);
}

/**
 * proc_dointvec - read a vector of integers
 * @table: the sysctl table
 * @write: %TRUE if this is a write to the sysctl file
 * @filp: the file structure
 * @buffer: the user buffer
 * @lenp: the size of the user buffer
 * @ppos: file position
 *
 * Reads/writes up to table->maxlen/sizeof(unsigned int) integer
 * values from/to the user buffer, treated as an ASCII string. 
 *
 * Returns 0 on success.
 */
int proc_dointvec(ctl_table *table, int write, struct file *filp,
		     void __user *buffer, size_t *lenp, loff_t *ppos)
{
    return do_proc_dointvec(table,write,filp,buffer,lenp,ppos,
		    	    NULL,NULL);
}

#define OP_SET	0
#define OP_AND	1
#define OP_OR	2

static int do_proc_dointvec_bset_conv(int *negp, unsigned long *lvalp,
				      int *valp,
				      int write, void *data)
{
	int op = *(int *)data;
	if (write) {
		int val = *negp ? -*lvalp : *lvalp;
		switch(op) {
		case OP_SET:	*valp = val; break;
		case OP_AND:	*valp &= val; break;
		case OP_OR:	*valp |= val; break;
		}
	} else {
		int val = *valp;
		if (val < 0) {
			*negp = -1;
			*lvalp = (unsigned long)-val;
		} else {
			*negp = 0;
			*lvalp = (unsigned long)val;
		}
	}
	return 0;
}

/*
 *	init may raise the set.
 */
 
int proc_dointvec_bset(ctl_table *table, int write, struct file *filp,
			void __user *buffer, size_t *lenp, loff_t *ppos)
{
	int op;

	if (write && !capable(CAP_SYS_MODULE)) {
		return -EPERM;
	}

	op = is_init(current) ? OP_SET : OP_AND;
	return do_proc_dointvec(table,write,filp,buffer,lenp,ppos,
				do_proc_dointvec_bset_conv,&op);
}

/*
 *	Taint values can only be increased
 */
static int proc_dointvec_taint(ctl_table *table, int write, struct file *filp,
			       void __user *buffer, size_t *lenp, loff_t *ppos)
{
	int op;

	if (write && !capable(CAP_SYS_ADMIN))
		return -EPERM;

	op = OP_OR;
	return do_proc_dointvec(table,write,filp,buffer,lenp,ppos,
				do_proc_dointvec_bset_conv,&op);
}

struct do_proc_dointvec_minmax_conv_param {
	int *min;
	int *max;
};

static int do_proc_dointvec_minmax_conv(int *negp, unsigned long *lvalp, 
					int *valp, 
					int write, void *data)
{
	struct do_proc_dointvec_minmax_conv_param *param = data;
	if (write) {
		int val = *negp ? -*lvalp : *lvalp;
		if ((param->min && *param->min > val) ||
		    (param->max && *param->max < val))
			return -EINVAL;
		*valp = val;
	} else {
		int val = *valp;
		if (val < 0) {
			*negp = -1;
			*lvalp = (unsigned long)-val;
		} else {
			*negp = 0;
			*lvalp = (unsigned long)val;
		}
	}
	return 0;
}

/**
 * proc_dointvec_minmax - read a vector of integers with min/max values
 * @table: the sysctl table
 * @write: %TRUE if this is a write to the sysctl file
 * @filp: the file structure
 * @buffer: the user buffer
 * @lenp: the size of the user buffer
 * @ppos: file position
 *
 * Reads/writes up to table->maxlen/sizeof(unsigned int) integer
 * values from/to the user buffer, treated as an ASCII string.
 *
 * This routine will ensure the values are within the range specified by
 * table->extra1 (min) and table->extra2 (max).
 *
 * Returns 0 on success.
 */
int proc_dointvec_minmax(ctl_table *table, int write, struct file *filp,
		  void __user *buffer, size_t *lenp, loff_t *ppos)
{
	struct do_proc_dointvec_minmax_conv_param param = {
		.min = (int *) table->extra1,
		.max = (int *) table->extra2,
	};
	return do_proc_dointvec(table, write, filp, buffer, lenp, ppos,
				do_proc_dointvec_minmax_conv, &param);
}

static int __do_proc_doulongvec_minmax(void *data, ctl_table *table, int write,
				     struct file *filp,
				     void __user *buffer,
				     size_t *lenp, loff_t *ppos,
				     unsigned long convmul,
				     unsigned long convdiv)
{
#define TMPBUFLEN 21
	unsigned long *i, *min, *max, val;
	int vleft, first=1, neg;
	size_t len, left;
	char buf[TMPBUFLEN], *p;
	char __user *s = buffer;
	
	if (!data || !table->maxlen || !*lenp ||
	    (*ppos && !write)) {
		*lenp = 0;
		return 0;
	}
	
	i = (unsigned long *) data;
	min = (unsigned long *) table->extra1;
	max = (unsigned long *) table->extra2;
	vleft = table->maxlen / sizeof(unsigned long);
	left = *lenp;
	
	for (; left && vleft--; i++, min++, max++, first=0) {
		if (write) {
			while (left) {
				char c;
				if (get_user(c, s))