// SPDX-License-Identifier: GPL-2.0
/*
* NETLINK Netlink attributes
*
* Authors: Thomas Graf <tgraf@suug.ch>
* Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
*/
#include <linux/export.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/jiffies.h>
#include <linux/skbuff.h>
#include <linux/string.h>
#include <linux/types.h>
#include <net/netlink.h>
/* For these data types, attribute length should be exactly the given
* size. However, to maintain compatibility with broken commands, if the
* attribute length does not match the expected size a warning is emitted
* to the user that the command is sending invalid data and needs to be fixed.
*/
static const u8 nla_attr_len[NLA_TYPE_MAX+1] = {
[NLA_U8] = sizeof(u8),
[NLA_U16] = sizeof(u16),
[NLA_U32] = sizeof(u32),
[NLA_U64] = sizeof(u64),
[NLA_S8] = sizeof(s8),
[NLA_S16] = sizeof(s16),
[NLA_S32] = sizeof(s32),
[NLA_S64] = sizeof(s64),
};
static const u8 nla_attr_minlen[NLA_TYPE_MAX+1] = {
[NLA_U8] = sizeof(u8),
[NLA_U16] = sizeof(u16),
[NLA_U32] = sizeof(u32),
[NLA_U64] = sizeof(u64),
[NLA_MSECS] = sizeof(u64),
[NLA_NESTED] = NLA_HDRLEN,
[NLA_S8] = sizeof(s8),
[NLA_S16] = sizeof(s16),
[NLA_S32] = sizeof(s32),
[NLA_S64] = sizeof(s64),
};
static int validate_nla_bitfield32(const struct nlattr *nla,
const u32 *valid_flags_mask)
{
const struct nla_bitfield32 *bf = nla_data(nla);
if (!valid_flags_mask)
return -EINVAL;
/*disallow invalid bit selector */
if (bf->selector & ~*valid_flags_mask)
return -EINVAL;
/*disallow invalid bit values */
if (bf->value & ~*valid_flags_mask)
return -EINVAL;
/*disallow valid bit values that are not selected*/
if (bf->value & ~bf->selector)
return -EINVAL;
return 0;
}
static int nla_validate_array(const struct nlattr *head, int len, int maxtype,
const struct nla_policy *policy,
struct netlink_ext_ack *extack)
{
const struct nlattr *entry;
int rem;
nla_for_each_attr(entry, head, len, rem) {
int ret;
if (nla_len(entry) == 0)
continue;
if (nla_len(entry) < NLA_HDRLEN) {
NL_SET_ERR_MSG_ATTR(extack, entry,
"Array element too short");
return -ERANGE;
}
ret = nla_validate(nla_data(entry), nla_len(entry),
maxtype, policy, extack);
if (ret < 0)
return ret;
}
return 0;
}
static int nla_validate_int_range(const struct nla_policy *pt,
const struct nlattr *nla,
struct netlink_ext_ack *extack)
{
bool validate_min, validate_max;
s64 value;
validate_min = pt->validation_type == NLA_VALIDATE_RANGE ||
pt->validation_type == NLA_VALIDATE_MIN;
validate_max = pt->validation_type == NLA_VALIDATE_RANGE ||
pt->validation_type == NLA_VALIDATE_MAX;
switch (pt->type) {
case NLA_U8:
value = nla_get_u8(nla);
break;
case NLA_U16:
value = nla_get_u16(nla);
break;
case NLA_U32:
value = nla_get_u32(nla);
break;
case NLA_S8:
value = nla_get_s8(nla);
break;
case NLA_S16:
value = nla_get_s16(nla);
break;
case NLA_S32:
value = nla_get_s32(nla);
break;
case NLA_S64:
value = nla_get_s64(nla);
break;
case NLA_U64:
/* treat this one specially, since it may not fit into s64 */
if ((validate_min && nla_get_u64(nla) < pt->min) ||
(validate_max && nla_get_u64(nla) > pt->max)) {
NL_SET_ERR_MSG_ATTR(extack, nla,
"integer out of range");
return -ERANGE;
}
return 0;
default:
WARN_ON(1);
return -EINVAL;
}
if ((validate_min && value < pt->min) ||
(validate_max && value > pt->max)) {
NL_SET_ERR_MSG_ATTR(extack, nla,
"integer out of range");
return -ERANGE;
}
return 0;
}
static int validate_nla(const struct nlattr *nla, int maxtype,
const struct nla_policy *policy,
struct netlink_ext_ack *extack)
{
const struct nla_policy *pt;
int minlen = 0, attrlen = nla_len(nla), type = nla_type(nla);
int err = -ERANGE;
if (type <= 0 || type > maxtype)
return 0;
pt = &policy[type];
BUG_ON(pt->type > NLA_TYPE_MAX);
if ((nla_attr_len[pt->type] && attrlen != nla_attr_len[pt->type]) ||
(pt->type == NLA_EXACT_LEN_WARN && attrlen != pt->len)) {
pr_warn_ratelimited("netlink: '%s': attribute type %d has an invalid length.\n",
current->comm, type);
}
switch (pt->type) {
case NLA_EXACT_LEN:
if (attrlen != pt->len)
goto out_err;
break;
case NLA_REJECT:
if (extack && pt->validation_data) {
NL_SET_BAD_ATTR(extack, nla);
extack->_msg = pt->validation_data;
return -EINVAL;
}
err = -EINVAL;
goto out_err;
case NLA_FLAG:
if (attrlen > 0)
goto out_err;
break;
case NLA_BITFIELD32:
if (attrlen != sizeof(struct nla_bitfield32))
goto out_err;
err = validate_nla_bitfield32(nla, pt->validation_data);
if (err)
goto out_err;
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) {
err = -EINVAL;
goto out_err;
}
/* fall through */
case NLA_STRING:
if (attrlen < 1)
goto out_err;
if (pt->len) {
char *buf = nla_data(nla);
if (buf[attrlen - 1] == '\0')
attrlen--;
if (attrlen > pt->len)
goto out_err;
}
break;
case NLA_BINARY:
if (pt->len && attrlen > pt->len)
goto out_err;
break;
case NLA_NESTED:
/* a nested attributes is allowed to be empty; if its not,
* it must have a size of at least NLA_HDRLEN.
*/
if (attrlen == 0)
break;
if (attrlen < NLA_HDRLEN)
goto out_err;
if (pt->validation_data) {
err = nla_validate(nla_data(nla), nla_len(nla), pt->len,
pt->validation_data, extack);
if (err < 0) {
/*
* return directly to preserve the inner
* error message/attribute pointer
*/
return err;
}
}
break;
case NLA_NESTED_ARRAY:
/* a nested array attribute is allowed to be empty; if its not,
* it must have a size of at least NLA_HDRLEN.
*/
if (attrlen == 0)
break;
if (attrlen < NLA_HDRLEN)
goto out_err;
if (pt->validation_data) {
int err;
err = nla_validate_array(nla_data(nla), nla_len(nla),
pt->len, pt->validation_data,
extack);
if (err < 0) {
/*
* return directly to preserve the inner
* error message/attribute pointer
*/
return err;
}
}
break;
default:
if (pt->len)
minlen = pt->len;
else if (pt->type != NLA_UNSPEC)
minlen = nla_attr_minlen[pt->type];
if (attrlen < minlen)
goto out_err;
}
/* further validation */
switch (pt->validation_type) {
case NLA_VALIDATE_NONE:
/* nothing to do */
break;
case NLA_VALIDATE_RANGE:
case NLA_VALIDATE_MIN:
case NLA_VALIDATE_MAX:
err = nla_validate_int_range(pt, nla, extack);
if (err)
return err;
break;
case NLA_VALIDATE_FUNCTION:
if (pt->validate) {
err = pt->validate(nla, extack);
if (err)
return err;
}
break;
}
return 0;
out_err:
NL_SET_ERR_MSG_ATTR(extack, nla, "Attribute failed policy validation");
return err;
}
/**
* 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
* @extack: extended ACK report struct
*
* 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(const struct nlattr *head, int len, int maxtype,
const struct nla_policy *policy,
struct netlink_ext_ack *extack)
{
const struct nlattr *nla;
int rem;
nla_for_each_attr(nla, head, len, rem) {
int err = validate_nla(nla, maxtype, policy, extack);
if (err < 0)
return err;
}
return 0;
}
EXPORT_SYMBOL(nla_validate);
/**
* nla_policy_len - Determin the max. length of a policy
* @policy: policy to use
* @n: number of policies
*
* Determines the max. length of the policy. It is currently used
* to allocated Netlink buffers roughly the size of the actual
* message.
*
* Returns 0 on success or a negative error code.
*/
int
nla_policy_len(const struct nla_policy *p, int n)
{
int i, len = 0;
for (i = 0; i < n; i++, p++) {
if (p->len)
len += nla_total_size(p->len);
else if (nla_attr_len[p->type])
len += nla_total_size(nla_attr_len[p->type]);
else if (nla_attr_minlen[p->type])
len += nla_total_size(nla_attr_minlen[p->type]);
}
return len;
}
EXPORT_SYMBOL(nla_policy_len);
/**
* 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
* @policy: validation policy
*
* Parses a stream of attributes and stores a pointer to each attribute in
* the tb array accessible 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.
*/
static int __nla_parse(struct nlattr **tb, int maxtype,
const struct nlattr *head, int len,
bool strict, const struct nla_policy *policy,
struct netlink_ext_ack *extack)
{
const struct nlattr *nla;
int rem;
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 (strict) {
NL_SET_ERR_MSG(extack, "Unknown attribute type");
return -EINVAL;
}
continue;
}
if (policy) {
int err = validate_nla(nla, maxtype, policy, extack);
if (err < 0)
return err;
}
tb[type] = (struct nlattr *)nla;
}
if (unlikely(rem > 0)) {
pr_warn_ratelimited("netlink: %d bytes leftover after parsing attributes in process `%s'.\n",
rem, current->comm);
NL_SET_ERR_MSG(extack, "bytes leftover after parsing attributes");
if (strict)
return -EINVAL;
}
return 0;
}
int nla_parse(struct nlattr **tb, int maxtype, const struct nlattr *head,
int len, const struct nla_policy *policy,
struct netlink_ext_ack *extack)
{
return __nla_parse(tb, maxtype, head, len, false, policy, extack);
}
EXPORT_SYMBOL(nla_parse);
int nla_parse_strict(struct nlattr **tb, int maxtype, const struct nlattr *head,
int len, const struct nla_policy *policy,
struct netlink_ext_ack *extack)
{
return __nla_parse(tb, maxtype, head, len, true, policy, extack);
}
EXPORT_SYMBOL(nla_parse_strict);
/**
* 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(const struct nlattr *head, int len, int attrtype)
{
const struct nlattr *nla;
int rem;
nla_for_each_attr(nla, head, len, rem)
if (nla_type(nla) == attrtype)
return (struct nlattr *)nla;
return NULL;
}
EXPORT_SYMBOL(nla_find);
/**
* nla_strlcpy - Copy string attribute payload into a sized buffer
* @dst: where to copy the string to
* @nla: 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;
}
EXPORT_SYMBOL(nla_strlcpy);
/**
* nla_strdup - Copy string attribute payload into a newly allocated buffer
* @nla: attribute to copy the string from
* @flags: the type of memory to allocate (see kmalloc).
*
* Returns a pointer to the allocated buffer or NULL on error.
*/
char *nla_strdup(const struct nlattr *nla, gfp_t flags)
{
size_t srclen = nla_len(nla);
char *src = nla_data(nla), *dst;
if (srclen > 0 && src[srclen - 1] == '\0')
srclen--;
dst = kmalloc(srclen + 1, flags);
if (dst != NULL) {
memcpy(dst, src, srclen);
dst[srclen] = '\0';
}
return dst;
}
EXPORT_SYMBOL(nla_strdup);
/**
* 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, const struct nlattr *src, int count)
{
int minlen = min_t(int, count, nla_len(src));
memcpy(dest, nla_data(src), minlen);
if (count > minlen)
memset(dest + minlen, 0, count - minlen);
return minlen;
}
EXPORT_SYMBOL(nla_memcpy);
/**
* 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;
}
EXPORT_SYMBOL(nla_memcmp);
/**
* 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);
char *buf = nla_data(nla);
int attrlen = nla_len(nla);
int d;
if (attrlen > 0 && buf[attrlen - 1] == '\0')
attrlen--;
d = attrlen - len;
if (d == 0)
d = memcmp(nla_data(nla), str, len);
return d;
}
EXPORT_SYMBOL(nla_strcmp);
#ifdef CONFIG_NET
/**
* __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 = 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;
}
EXPORT_SYMBOL(__nla_reserve);
/**
* __nla_reserve_64bit - reserve room for attribute on the skb and align it
* @skb: socket buffer to reserve room on
* @attrtype: attribute type
* @attrlen: length of attribute payload
* @padattr: attribute type for the padding
*
* Adds a netlink attribute header to a socket buffer and reserves
* room for the payload but does not copy it. It also ensure that this
* attribute will have a 64-bit aligned nla_data() area.
*
* The caller is responsible to ensure that the skb provides enough
* tailroom for the attribute header and payload.
*/
struct nlattr *__nla_reserve_64bit(struct sk_buff *skb, int attrtype,
int attrlen, int padattr)
{
if (nla_need_padding_for_64bit(skb))
nla_align_64bit(skb, padattr);
return __nla_reserve(skb, attrtype, attrlen);
}
EXPORT_SYMBOL(__nla_reserve_64bit);
/**
* __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)
{
return skb_put_zero(skb, NLA_ALIGN(attrlen));
}
EXPORT_SYMBOL(__nla_reserve_nohdr);
/**
* 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);
}
EXPORT_SYMBOL(nla_reserve);
/**
* nla_reserve_64bit - reserve room for attribute on the skb and align it
* @skb: socket buffer to reserve room on
* @attrtype: attribute type
* @attrlen: length of attribute payload
* @padattr: attribute type for the padding
*
* Adds a netlink attribute header to a socket buffer and reserves
* room for the payload but does not copy it. It also ensure that this
* attribute will have a 64-bit aligned nla_data() area.
*
* Returns NULL if the tailroom of the skb is insufficient to store
* the attribute header and payload.
*/
struct nlattr *nla_reserve_64bit(struct sk_buff *skb, int attrtype, int attrlen,
int padattr)
{
size_t len;
if (nla_need_padding_for_64bit(skb))
len = nla_total_size_64bit(attrlen);
else
len = nla_total_size(attrlen);
if (unlikely(skb_tailroom(skb) < len))
return NULL;
return __nla_reserve_64bit(skb, attrtype, attrlen, padattr);
}
EXPORT_SYMBOL(nla_reserve_64bit);
/**
* 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.
*
* 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);
}
EXPORT_SYMBOL(nla_reserve_nohdr);
/**
* __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);
}
EXPORT_SYMBOL(__nla_put);
/**
* __nla_put_64bit - Add a netlink attribute to a socket buffer and align it
* @skb: socket buffer to add attribute to
* @attrtype: attribute type
* @attrlen: length of attribute payload
* @data: head of attribute payload
* @padattr: attribute type for the padding
*
* The caller is responsible to ensure that the skb provides enough
* tailroom for the attribute header and payload.
*/
void __nla_put_64bit(struct sk_buff *skb, int attrtype, int attrlen,
const void *data, int padattr)
{
struct nlattr *nla;
nla = __nla_reserve_64bit(skb, attrtype, attrlen, padattr);
memcpy(nla_data(nla), data, attrlen);
}
EXPORT_SYMBOL(__nla_put_64bit);
/**
* __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);
}
EXPORT_SYMBOL(__nla_put_nohdr);
/**
* 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 -EMSGSIZE 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 -EMSGSIZE;
__nla_put(skb, attrtype, attrlen, data);
return 0;
}
EXPORT_SYMBOL(nla_put);
/**
* nla_put_64bit - Add a netlink attribute to a socket buffer and align it
* @skb: socket buffer to add attribute to
* @attrtype: attribute type
* @attrlen: length of attribute payload
* @data: head of attribute payload
* @padattr: attribute type for the padding
*
* Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
* the attribute header and payload.
*/
int nla_put_64bit(struct sk_buff *skb, int attrtype, int attrlen,
const void *data, int padattr)
{
size_t len;
if (nla_need_padding_for_64bit(skb))
len = nla_total_size_64bit(attrlen);
else
len = nla_total_size(attrlen);
if (unlikely(skb_tailroom(skb) < len))
return -EMSGSIZE;
__nla_put_64bit(skb, attrtype, attrlen, data, padattr);
return 0;
}
EXPORT_SYMBOL(nla_put_64bit);
/**
* 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 -EMSGSIZE 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 -EMSGSIZE;
__nla_put_nohdr(skb, attrlen, data);
return 0;
}
EXPORT_SYMBOL(nla_put_nohdr);
/**
* nla_append - Add a netlink attribute without header or padding
* @skb: socket buffer to add attribute to
* @attrlen: length of attribute payload
* @data: head of attribute payload
*
* Returns -EMSGSIZE if the tailroom of the skb is insufficient to store
* the attribute payload.
*/
int nla_append(struct sk_buff *skb, int attrlen, const void *data)
{
if (unlikely(skb_tailroom(skb) < NLA_ALIGN(attrlen)))
return -EMSGSIZE;
skb_put_data(skb, data, attrlen);
return 0;
}
EXPORT_SYMBOL(nla_append);
#endif
