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/*

 * NETLINK      Netlink attributes

 *

 *              Authors:        Thomas Graf <tgraf@suug.ch>

 *                              Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>

 */

#include <linux/module.h>

#include <linux/kernel.h>

#include <linux/errno.h>

#include <linux/jiffies.h>

#include <linux/netdevice.h>

#include <linux/skbuff.h>

#include <linux/string.h>

#include <linux/types.h>

#include <net/netlink.h>

static u16 nla_attr_minlen[NLA_TYPE_MAX+1] __read_mostly = {

        [NLA_U8]        = sizeof(u8),

        [NLA_U16]       = sizeof(u16),

        [NLA_U32]       = sizeof(u32),

        [NLA_U64]       = sizeof(u64),

        [NLA_NESTED]    = NLA_HDRLEN,

};

static int validate_nla(struct nlattr *nla, int maxtype,

                        const struct nla_policy *policy)

{

        const struct nla_policy *pt;

        int minlen = 0, attrlen = nla_len(nla), type = nla_type(nla);

        if (type <= 0 || type > maxtype)

                return 0;

        pt = &policy[type];

        BUG_ON(pt->type > NLA_TYPE_MAX);

        switch (pt->type) {

        case NLA_FLAG:

                if (attrlen > 0)

                        return -ERANGE;

                break;

        case NLA_NUL_STRING:

                if (pt->len)

                        minlen = min_t(int, attrlen, pt->len + 1);

                else

                        minlen = attrlen;

                if (!minlen || memchr(nla_data(nla), '\0', minlen) == NULL)

                        return -EINVAL;

                /* fall through */

        case NLA_STRING:

                if (attrlen < 1)

                        return -ERANGE;

                if (pt->len) {

                        char *buf = nla_data(nla);

                        if (buf[attrlen - 1] == '\0')

                                attrlen--;

                        if (attrlen > pt->len)

                                return -ERANGE;

                }

                break;

        case NLA_BINARY:

                if (pt->len && attrlen > pt->len)

                        return -ERANGE;

                break;

        case NLA_NESTED_COMPAT:

                if (attrlen < pt->len)

                        return -ERANGE;

                if (attrlen < NLA_ALIGN(pt->len))

                        break;

                if (attrlen < NLA_ALIGN(pt->len) + NLA_HDRLEN)

                        return -ERANGE;

                nla = nla_data(nla) + NLA_ALIGN(pt->len);

                if (attrlen < NLA_ALIGN(pt->len) + NLA_HDRLEN + nla_len(nla))

                        return -ERANGE;

                break;

        default:

                if (pt->len)

                        minlen = pt->len;

                else if (pt->type != NLA_UNSPEC)

                        minlen = nla_attr_minlen[pt->type];

                if (attrlen < minlen)

                        return -ERANGE;

        }

        return 0;

}

/**

 * nla_validate - Validate a stream of attributes

 * @head: head of attribute stream

 * @len: length of attribute stream

 * @maxtype: maximum attribute type to be expected

 * @policy: validation policy

 *

 * Validates all attributes in the specified attribute stream against the

 * specified policy. Attributes with a type exceeding maxtype will be

 * ignored. See documenation of struct nla_policy for more details.

 *

 * Returns 0 on success or a negative error code.

 */

int nla_validate(struct nlattr *head, int len, int maxtype,

                 const struct nla_policy *policy)

{

        struct nlattr *nla;

        int rem, err;

        nla_for_each_attr(nla, head, len, rem) {

                err = validate_nla(nla, maxtype, policy);

                if (err < 0)

                        goto errout;

        }

        err = 0;

errout:

        return err;

}

/**

 * nla_parse - Parse a stream of attributes into a tb buffer

 * @tb: destination array with maxtype+1 elements

 * @maxtype: maximum attribute type to be expected

 * @head: head of attribute stream

 * @len: length of attribute stream

 *

 * Parses a stream of attributes and stores a pointer to each attribute in

 * the tb array accessable via the attribute type. Attributes with a type

 * exceeding maxtype will be silently ignored for backwards compatibility

 * reasons. policy may be set to NULL if no validation is required.

 *

 * Returns 0 on success or a negative error code.

 */

int nla_parse(struct nlattr *tb[], int maxtype, struct nlattr *head, int len,

              const struct nla_policy *policy)

{

        struct nlattr *nla;

        int rem, err;

        memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));

        nla_for_each_attr(nla, head, len, rem) {

                u16 type = nla_type(nla);

                if (type > 0 && type <= maxtype) {

                        if (policy) {

                                err = validate_nla(nla, maxtype, policy);

                                if (err < 0)

                                        goto errout;

                        }

                        tb[type] = nla;

                }

        }

        if (unlikely(rem > 0))

                printk(KERN_WARNING "netlink: %d bytes leftover after parsing "

                       "attributes.\n", rem);

        err = 0;

errout:

        return err;

}

/**

 * nla_find - Find a specific attribute in a stream of attributes

 * @head: head of attribute stream

 * @len: length of attribute stream

 * @attrtype: type of attribute to look for

 *

 * Returns the first attribute in the stream matching the specified type.

 */

struct nlattr *nla_find(struct nlattr *head, int len, int attrtype)

{

        struct nlattr *nla;

        int rem;

        nla_for_each_attr(nla, head, len, rem)

                if (nla_type(nla) == attrtype)

                        return nla;

        return NULL;

}

/**

 * nla_strlcpy - Copy string attribute payload into a sized buffer

 * @dst: where to copy the string to

 * @src: attribute to copy the string from

 * @dstsize: size of destination buffer

 *

 * Copies at most dstsize - 1 bytes into the destination buffer.

 * The result is always a valid NUL-terminated string. Unlike

 * strlcpy the destination buffer is always padded out.

 *

 * Returns the length of the source buffer.

 */

size_t nla_strlcpy(char *dst, const struct nlattr *nla, size_t dstsize)

{

        size_t srclen = nla_len(nla);

        char *src = nla_data(nla);

        if (srclen > 0 && src[srclen - 1] == '\0')

                srclen--;

        if (dstsize > 0) {

                size_t len = (srclen >= dstsize) ? dstsize - 1 : srclen;

                memset(dst, 0, dstsize);

                memcpy(dst, src, len);

        }

        return srclen;

}

/**

 * nla_memcpy - Copy a netlink attribute into another memory area

 * @dest: where to copy to memcpy

 * @src: netlink attribute to copy from

 * @count: size of the destination area

 *

 * Note: The number of bytes copied is limited by the length of

 *       attribute's payload. memcpy

 *

 * Returns the number of bytes copied.

 */

int nla_memcpy(void *dest, struct nlattr *src, int count)

{

        int minlen = min_t(int, count, nla_len(src));

        memcpy(dest, nla_data(src), minlen);

        return minlen;

}

/**

 * nla_memcmp - Compare an attribute with sized memory area

 * @nla: netlink attribute

 * @data: memory area

 * @size: size of memory area

 */

int nla_memcmp(const struct nlattr *nla, const void *data,

                             size_t size)

{

        int d = nla_len(nla) - size;

        if (d == 0)

                d = memcmp(nla_data(nla), data, size);

        return d;

}

/**

 * nla_strcmp - Compare a string attribute against a string

 * @nla: netlink string attribute

 * @str: another string

 */

int nla_strcmp(const struct nlattr *nla, const char *str)

{

        int len = strlen(str) + 1;

        int d = nla_len(nla) - len;

        if (d == 0)

                d = memcmp(nla_data(nla), str, len);

        return d;

}

/**

 * __nla_reserve - reserve room for attribute on the skb

 * @skb: socket buffer to reserve room on

 * @attrtype: attribute type

 * @attrlen: length of attribute payload

 *

 * Adds a netlink attribute header to a socket buffer and reserves

 * room for the payload but does not copy it.

 *

 * The caller is responsible to ensure that the skb provides enough

 * tailroom for the attribute header and payload.

 */

struct nlattr *__nla_reserve(struct sk_buff *skb, int attrtype, int attrlen)

{

        struct nlattr *nla;

        nla = (struct nlattr *) skb_put(skb, nla_total_size(attrlen));

        nla->nla_type = attrtype;

        nla->nla_len = nla_attr_size(attrlen);

        memset((unsigned char *) nla + nla->nla_len, 0, nla_padlen(attrlen));

        return nla;

}

/**

 * __nla_reserve_nohdr - reserve room for attribute without header

 * @skb: socket buffer to reserve room on

 * @attrlen: length of attribute payload

 *

 * Reserves room for attribute payload without a header.

 *

 * The caller is responsible to ensure that the skb provides enough

 * tailroom for the payload.

 */

void *__nla_reserve_nohdr(struct sk_buff *skb, int attrlen)

{

        void *start;

        start = skb_put(skb, NLA_ALIGN(attrlen));

        memset(start, 0, NLA_ALIGN(attrlen));

        return start;

}

/**

 * nla_reserve - reserve room for attribute on the skb

 * @skb: socket buffer to reserve room on

 * @attrtype: attribute type

 * @attrlen: length of attribute payload

 *

 * Adds a netlink attribute header to a socket buffer and reserves

 * room for the payload but does not copy it.

 *

 * Returns NULL if the tailroom of the skb is insufficient to store

 * the attribute header and payload.

 */

struct nlattr *nla_reserve(struct sk_buff *skb, int attrtype, int attrlen)

{

        if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen)))

                return NULL;

        return __nla_reserve(skb, attrtype, attrlen);

}

/**

 * nla_reserve - reserve room for attribute without header

 * @skb: socket buffer to reserve room on

 * @len: length of attribute payload

 *

 * Reserves room for attribute payload without a header.

 *

 * Returns NULL if the tailroom of the skb is insufficient to store

 * the attribute payload.

 */

void *nla_reserve_nohdr(struct sk_buff *skb, int attrlen)

{

        if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))

                return NULL;

        return __nla_reserve_nohdr(skb, attrlen);

}

/**

 * __nla_put - Add a netlink attribute to a socket buffer

 * @skb: socket buffer to add attribute to

 * @attrtype: attribute type

 * @attrlen: length of attribute payload

 * @data: head of attribute payload

 *

 * The caller is responsible to ensure that the skb provides enough

 * tailroom for the attribute header and payload.

 */

void __nla_put(struct sk_buff *skb, int attrtype, int attrlen,

                             const void *data)

{

        struct nlattr *nla;

        nla = __nla_reserve(skb, attrtype, attrlen);

        memcpy(nla_data(nla), data, attrlen);

}

/**

 * __nla_put_nohdr - Add a netlink attribute without header

 * @skb: socket buffer to add attribute to

 * @attrlen: length of attribute payload

 * @data: head of attribute payload

 *

 * The caller is responsible to ensure that the skb provides enough

 * tailroom for the attribute payload.

 */

void __nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data)

{

        void *start;

        start = __nla_reserve_nohdr(skb, attrlen);

        memcpy(start, data, attrlen);

}

/**

 * nla_put - Add a netlink attribute to a socket buffer

 * @skb: socket buffer to add attribute to

 * @attrtype: attribute type

 * @attrlen: length of attribute payload

 * @data: head of attribute payload

 *

 * Returns -1 if the tailroom of the skb is insufficient to store

 * the attribute header and payload.

 */

int nla_put(struct sk_buff *skb, int attrtype, int attrlen, const void *data)

{

        if (unlikely(skb_tailroom(skb) < nla_total_size(attrlen)))

                return -1;

        __nla_put(skb, attrtype, attrlen, data);

        return 0;

}

/**

 * nla_put_nohdr - Add a netlink attribute without header

 * @skb: socket buffer to add attribute to

 * @attrlen: length of attribute payload

 * @data: head of attribute payload

 *

 * Returns -1 if the tailroom of the skb is insufficient to store

 * the attribute payload.

 */

int nla_put_nohdr(struct sk_buff *skb, int attrlen, const void *data)

{

        if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))

                return -1;

        __nla_put_nohdr(skb, attrlen, data);

        return 0;

}

EXPORT_SYMBOL(nla_validate);

EXPORT_SYMBOL(nla_parse);

EXPORT_SYMBOL(nla_find);

EXPORT_SYMBOL(nla_strlcpy);

EXPORT_SYMBOL(__nla_reserve);

EXPORT_SYMBOL(__nla_reserve_nohdr);

EXPORT_SYMBOL(nla_reserve);

EXPORT_SYMBOL(nla_reserve_nohdr);

EXPORT_SYMBOL(__nla_put);

EXPORT_SYMBOL(__nla_put_nohdr);

EXPORT_SYMBOL(nla_put);

EXPORT_SYMBOL(nla_put_nohdr);

EXPORT_SYMBOL(nla_memcpy);

EXPORT_SYMBOL(nla_memcmp);

EXPORT_SYMBOL(nla_strcmp);