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netlink: use consistent variable lifetime in the default snl(3) parsers.

Browse source 
Currently, parsers use original strings/nla pointers instead of
duplicating them. These pointers refer to the temporary packet buffer,
 which can be silently rewritten when the next message is read.
Instead, duplicate all string/nla attributes using snl_allocz(3) to
 give control over variable lifetime to the user.

MFC after:	2 weeks
This commit is contained in:
Alexander V. Chernikov 2023-05-09 14:45:57 +00:00
parent de9bed030f
commit ba9c815d30
2 changed files with 53 additions and 8 deletions
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45
sys/netlink/netlink_snl.h
View file

@ -606,6 +606,23 @@ snl_attr_copy_string(struct snl_state *ss, struct nlattr *nla,
return (false);
}
static inline bool
snl_attr_dup_string(struct snl_state *ss __unused, struct nlattr *nla,
const void *arg __unused, void *target)
{
size_t maxlen = NLA_DATA_LEN(nla);
if (strnlen((char *)NLA_DATA(nla), maxlen) < maxlen) {
char *buf = snl_allocz(ss, maxlen);
if (buf == NULL)
return (false);
memcpy(buf, NLA_DATA(nla), maxlen);
*((char **)target) = buf;
return (true);
}
return (false);
}
static inline bool
snl_attr_get_nested(struct snl_state *ss, struct nlattr *nla, const void *arg, void *target)
{
@ -623,6 +640,20 @@ snl_attr_get_nla(struct snl_state *ss __unused, struct nlattr *nla,
return (true);
}
static inline bool
snl_attr_dup_nla(struct snl_state *ss __unused, struct nlattr *nla,
const void *arg __unused, void *target)
{
void *ptr = snl_allocz(ss, nla->nla_len);
if (ptr != NULL) {
memcpy(ptr, nla, nla->nla_len);
*((void **)target) = ptr;
return (true);
}
return (false);
}
static inline bool
snl_attr_copy_struct(struct snl_state *ss, struct nlattr *nla,
const void *arg __unused, void *target)
@ -637,6 +668,20 @@ snl_attr_copy_struct(struct snl_state *ss, struct nlattr *nla,
return (false);
}
static inline bool
snl_attr_dup_struct(struct snl_state *ss, struct nlattr *nla,
const void *arg __unused, void *target)
{
void *ptr = snl_allocz(ss, NLA_DATA_LEN(nla));
if (ptr != NULL) {
memcpy(ptr, NLA_DATA(nla), NLA_DATA_LEN(nla));
*((void **)target) = ptr;
return (true);
}
return (false);
}
static inline void
snl_field_get_uint8(struct snl_state *ss __unused, void *src, void *target)
{

16
sys/netlink/netlink_snl_route_parsers.h
View file

@ -177,13 +177,13 @@ struct snl_parsed_link {
#define _IN(_field) offsetof(struct ifinfomsg, _field)
#define _OUT(_field) offsetof(struct snl_parsed_link, _field)
static const struct snl_attr_parser _nla_p_link[] = {
{ .type = IFLA_ADDRESS, .off = _OUT(ifla_address), .cb = snl_attr_get_nla },
{ .type = IFLA_BROADCAST, .off = _OUT(ifla_broadcast), .cb = snl_attr_get_nla },
{ .type = IFLA_IFNAME, .off = _OUT(ifla_ifname), .cb = snl_attr_get_string },
{ .type = IFLA_ADDRESS, .off = _OUT(ifla_address), .cb = snl_attr_dup_nla },
{ .type = IFLA_BROADCAST, .off = _OUT(ifla_broadcast), .cb = snl_attr_dup_nla },
{ .type = IFLA_IFNAME, .off = _OUT(ifla_ifname), .cb = snl_attr_dup_string },
{ .type = IFLA_MTU, .off = _OUT(ifla_mtu), .cb = snl_attr_get_uint32 },
{ .type = IFLA_OPERSTATE, .off = _OUT(ifla_operstate), .cb = snl_attr_get_uint8 },
{ .type = IFLA_IFALIAS, .off = _OUT(ifla_ifalias), .cb = snl_attr_get_string },
{ .type = IFLA_STATS64, .off = _OUT(ifla_stats64), .cb = snl_attr_copy_struct },
{ .type = IFLA_IFALIAS, .off = _OUT(ifla_ifalias), .cb = snl_attr_dup_string },
{ .type = IFLA_STATS64, .off = _OUT(ifla_stats64), .cb = snl_attr_dup_struct },
{ .type = IFLA_PROMISCUITY, .off = _OUT(ifla_promiscuity), .cb = snl_attr_get_uint32 },
{ .type = IFLA_CARRIER, .off = _OUT(ifla_carrier), .cb = snl_attr_get_uint8 },
};
@ -208,7 +208,7 @@ struct snl_parsed_link_simple {
#define _IN(_field) offsetof(struct ifinfomsg, _field)
#define _OUT(_field) offsetof(struct snl_parsed_link_simple, _field)
static struct snl_attr_parser _nla_p_link_s[] = {
{ .type = IFLA_IFNAME, .off = _OUT(ifla_ifname), .cb = snl_attr_get_string },
{ .type = IFLA_IFNAME, .off = _OUT(ifla_ifname), .cb = snl_attr_dup_string },
{ .type = IFLA_MTU, .off = _OUT(ifla_mtu), .cb = snl_attr_get_uint32 },
};
static struct snl_field_parser _fp_p_link_s[] = {
@ -240,7 +240,7 @@ SNL_DECLARE_ATTR_PARSER(_neigh_fbsd_parser, _nla_p_neigh_fbsd);
static struct snl_attr_parser _nla_p_neigh_s[] = {
{ .type = NDA_DST, .off = _OUT(nda_dst), .cb = snl_attr_get_ip },
{ .type = NDA_LLADDR , .off = _OUT(nda_lladdr), .cb = snl_attr_get_nla },
{ .type = NDA_LLADDR , .off = _OUT(nda_lladdr), .cb = snl_attr_dup_nla },
{ .type = NDA_PROBES, .off = _OUT(nda_probes), .cb = snl_attr_get_uint32 },
{ .type = NDA_IFINDEX, .off = _OUT(nda_ifindex), .cb = snl_attr_get_uint32 },
{ .type = NDA_FREEBSD, .arg = &_neigh_fbsd_parser, .cb = snl_attr_get_nested },
@ -270,7 +270,7 @@ struct snl_parsed_addr {
static struct snl_attr_parser _nla_p_addr_s[] = {
{ .type = IFA_ADDRESS, .off = _OUT(ifa_address), .cb = snl_attr_get_ip },
{ .type = IFA_LOCAL, .off = _OUT(ifa_local), .cb = snl_attr_get_ip },
{ .type = IFA_LABEL, .off = _OUT(ifa_label), .cb = snl_attr_get_string },
{ .type = IFA_LABEL, .off = _OUT(ifa_label), .cb = snl_attr_dup_string },
{ .type = IFA_BROADCAST, .off = _OUT(ifa_broadcast), .cb = snl_attr_get_ip },
};
static struct snl_field_parser _fp_p_addr_s[] = {