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Merge branch 'net-introduce-nlmsg_payload-helper'

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Breno Leitao says:

====================
net: Introduce nlmsg_payload helper

In the current codebase, there are multiple instances where the
structure size is checked before assigning it to a Netlink message. This
check is crucial for ensuring that the structure is correctly mapped
onto the Netlink message, providing a layer of security.

To streamline this process, Jakub Kicinski suggested creating a helper
function, `nlmsg_payload`, which verifies if the structure fits within
the message. If it does, the function returns the data; otherwise, it
returns NULL. This approach simplifies the code and reduces redundancy.

This patchset introduces the `nlmsg_payload` helper and updates several
parts of the code to use it. Further updates will follow in subsequent
patchsets.

v1: https://lore.kernel.org/20250411-nlmsg-v1-0-ddd4e065cb15@debian.org
====================

Link: https://patch.msgid.link/20250414-nlmsg-v2-0-3d90cb42c6af@debian.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Jakub Kicinski
2025-04-15 08:28:57 -07:00
parent 0418711f60 8ff9530361
commit 2f8cc49d86
6 changed files with 38 additions and 20 deletions
Download Patch File Download Diff File Expand all files Collapse all files

16
include/net/netlink.h
View File

@@ -611,6 +611,22 @@ static inline int nlmsg_len(const struct nlmsghdr *nlh)
return nlh->nlmsg_len - NLMSG_HDRLEN;
}
/**
* nlmsg_payload - message payload if the data fits in the len
* @nlh: netlink message header
* @len: struct length
*
* Returns: The netlink message payload/data if the length is sufficient,
* otherwise NULL.
*/
static inline void *nlmsg_payload(const struct nlmsghdr *nlh, size_t len)
{
if (nlh->nlmsg_len < nlmsg_msg_size(len))
return NULL;
return nlmsg_data(nlh);
}
/**
* nlmsg_attrdata - head of attributes data
* @nlh: netlink message header

14
net/core/fib_rules.c
View File

@@ -852,13 +852,14 @@ int fib_newrule(struct net *net, struct sk_buff *skb, struct nlmsghdr *nlh,
struct netlink_ext_ack *extack, bool rtnl_held)
{
struct fib_rule *rule = NULL, *r, *last = NULL;
struct fib_rule_hdr *frh = nlmsg_data(nlh);
int err = -EINVAL, unresolved = 0;
struct fib_rules_ops *ops = NULL;
struct nlattr *tb[FRA_MAX + 1];
bool user_priority = false;
struct fib_rule_hdr *frh;
if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh))) {
frh = nlmsg_payload(nlh, sizeof(*frh));
if (!frh) {
NL_SET_ERR_MSG(extack, "Invalid msg length");
goto errout;
}
@@ -980,13 +981,14 @@ int fib_delrule(struct net *net, struct sk_buff *skb, struct nlmsghdr *nlh,
struct netlink_ext_ack *extack, bool rtnl_held)
{
struct fib_rule *rule = NULL, *nlrule = NULL;
struct fib_rule_hdr *frh = nlmsg_data(nlh);
struct fib_rules_ops *ops = NULL;
struct nlattr *tb[FRA_MAX+1];
bool user_priority = false;
struct fib_rule_hdr *frh;
int err = -EINVAL;
if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh))) {
frh = nlmsg_payload(nlh, sizeof(*frh));
if (!frh) {
NL_SET_ERR_MSG(extack, "Invalid msg length");
goto errout;
}
@@ -1238,12 +1240,12 @@ static int fib_valid_dumprule_req(const struct nlmsghdr *nlh,
{
struct fib_rule_hdr *frh;
if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh))) {
frh = nlmsg_payload(nlh, sizeof(*frh));
if (!frh) {
NL_SET_ERR_MSG(extack, "Invalid header for fib rule dump request");
return -EINVAL;
}
frh = nlmsg_data(nlh);
if (frh->dst_len || frh->src_len || frh->tos || frh->table ||
frh->res1 || frh->res2 || frh->action || frh->flags) {
NL_SET_ERR_MSG(extack,

8
net/core/neighbour.c
View File

@@ -2430,12 +2430,12 @@ static int neightbl_valid_dump_info(const struct nlmsghdr *nlh,
{
struct ndtmsg *ndtm;
if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*ndtm))) {
ndtm = nlmsg_payload(nlh, sizeof(*ndtm));
if (!ndtm) {
NL_SET_ERR_MSG(extack, "Invalid header for neighbor table dump request");
return -EINVAL;
}
ndtm = nlmsg_data(nlh);
if (ndtm->ndtm_pad1 || ndtm->ndtm_pad2) {
NL_SET_ERR_MSG(extack, "Invalid values in header for neighbor table dump request");
return -EINVAL;
@@ -2855,12 +2855,12 @@ static int neigh_valid_get_req(const struct nlmsghdr *nlh,
struct ndmsg *ndm;
int err, i;
if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*ndm))) {
ndm = nlmsg_payload(nlh, sizeof(*ndm));
if (!ndm) {
NL_SET_ERR_MSG(extack, "Invalid header for neighbor get request");
return -EINVAL;
}
ndm = nlmsg_data(nlh);
if (ndm->ndm_pad1 || ndm->ndm_pad2 || ndm->ndm_state ||
ndm->ndm_type) {
NL_SET_ERR_MSG(extack, "Invalid values in header for neighbor get request");

4
net/core/rtnetlink.c
View File

@@ -4887,12 +4887,12 @@ static int valid_fdb_dump_strict(const struct nlmsghdr *nlh,
struct ndmsg *ndm;
int err, i;
if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*ndm))) {
ndm = nlmsg_payload(nlh, sizeof(*ndm));
if (!ndm) {
NL_SET_ERR_MSG(extack, "Invalid header for fdb dump request");
return -EINVAL;
}
ndm = nlmsg_data(nlh);
if (ndm->ndm_pad1 || ndm->ndm_pad2 || ndm->ndm_state ||
ndm->ndm_flags || ndm->ndm_type) {
NL_SET_ERR_MSG(extack, "Invalid values in header for fdb dump request");

8
net/ipv6/addrconf.c
View File

@@ -5346,12 +5346,12 @@ static int inet6_valid_dump_ifaddr_req(const struct nlmsghdr *nlh,
struct ifaddrmsg *ifm;
int err, i;
if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*ifm))) {
ifm = nlmsg_payload(nlh, sizeof(*ifm));
if (!ifm) {
NL_SET_ERR_MSG_MOD(extack, "Invalid header for address dump request");
return -EINVAL;
}
ifm = nlmsg_data(nlh);
if (ifm->ifa_prefixlen || ifm->ifa_flags || ifm->ifa_scope) {
NL_SET_ERR_MSG_MOD(extack, "Invalid values in header for address dump request");
return -EINVAL;
@@ -5484,7 +5484,8 @@ static int inet6_rtm_valid_getaddr_req(struct sk_buff *skb,
struct ifaddrmsg *ifm;
int i, err;
if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*ifm))) {
ifm = nlmsg_payload(nlh, sizeof(*ifm));
if (!ifm) {
NL_SET_ERR_MSG_MOD(extack, "Invalid header for get address request");
return -EINVAL;
}
@@ -5493,7 +5494,6 @@ static int inet6_rtm_valid_getaddr_req(struct sk_buff *skb,
return nlmsg_parse_deprecated(nlh, sizeof(*ifm), tb, IFA_MAX,
ifa_ipv6_policy, extack);
ifm = nlmsg_data(nlh);
if (ifm->ifa_prefixlen || ifm->ifa_flags || ifm->ifa_scope) {
NL_SET_ERR_MSG_MOD(extack, "Invalid values in header for get address request");
return -EINVAL;

8
net/mpls/af_mpls.c
View File

@@ -2095,12 +2095,12 @@ static int mpls_valid_fib_dump_req(struct net *net, const struct nlmsghdr *nlh,
struct rtmsg *rtm;
int err, i;
if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*rtm))) {
rtm = nlmsg_payload(nlh, sizeof(*rtm));
if (!rtm) {
NL_SET_ERR_MSG_MOD(extack, "Invalid header for FIB dump request");
return -EINVAL;
}
rtm = nlmsg_data(nlh);
if (rtm->rtm_dst_len || rtm->rtm_src_len || rtm->rtm_tos ||
rtm->rtm_table || rtm->rtm_scope || rtm->rtm_type ||
rtm->rtm_flags) {
@@ -2288,7 +2288,8 @@ static int mpls_valid_getroute_req(struct sk_buff *skb,
struct rtmsg *rtm;
int i, err;
if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*rtm))) {
rtm = nlmsg_payload(nlh, sizeof(*rtm));
if (!rtm) {
NL_SET_ERR_MSG_MOD(extack,
"Invalid header for get route request");
return -EINVAL;
@@ -2298,7 +2299,6 @@ static int mpls_valid_getroute_req(struct sk_buff *skb,
return nlmsg_parse_deprecated(nlh, sizeof(*rtm), tb, RTA_MAX,
rtm_mpls_policy, extack);
rtm = nlmsg_data(nlh);
if ((rtm->rtm_dst_len && rtm->rtm_dst_len != 20) ||
rtm->rtm_src_len || rtm->rtm_tos || rtm->rtm_table ||
rtm->rtm_protocol || rtm->rtm_scope || rtm->rtm_type) {