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netlink: return optional metadata with the operation result.

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Some operations like interface creation may need to return metadata
 - in this case, interface name - back to the caller if the operation
 is successful.
This change implements attaching an `NLMSGERR_ATTR_COOKIE` nla to the
operation reply message via `nlmsg_report_cookie()`.
Additionally, on successful interface creation, interface index and
 interface name are returned in the `IFLA_NEW_IFINDEX` and `IFLA_IFNAME
 TLVs, encapsulated in the `NLMSGERR_ATTR_COOKIE`.

Reviewed By: pauamma
Differential Revision: https://reviews.freebsd.org/D38283
MFC after:	1 week
This commit is contained in:
Alexander V. Chernikov 2023-02-09 14:53:44 +00:00
parent 08b0c98006
commit 25c2dd2f2c
9 changed files with 209 additions and 60 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
share/man/man4/netlink.4
View File

@ -217,6 +217,10 @@ socket option is set, the kernel may add a
string TLV with the textual error description, optionally followed by the
.Dv NLMSGERR_ATTR_OFFS
TLV, indicating the offset from the message start that triggered an error.
Some operations may return additional metadata encapsulated in the
.Dv NLMSGERR_ATTR_COOKIE
TLV.
The metadata format is specific to the operation.
If the operation reply is a multipart message, then no
.Dv NLMSG_ERROR
reply is generated, only a

7
share/man/man4/rtnetlink.4
View File

@ -284,6 +284,13 @@ struct ifinfomsg {
Creates a new interface.
The only mandatory TLV is
.Dv IFLA_IFNAME .
The following attributes are returned inside the nested
.Dv NLMSGERR_ATTR_COOKIE :
.Pp
.Bd -literal -offset indent -compact
IFLA_NEW_IFINDEX (uint32) created interface index
IFLA_IFNAME (string) created interface name
.Ed
.Ss RTM_DELLINK
Deletes the interface specified by
.Dv IFLA_IFNAME .

19
sys/netlink/netlink_message_parser.c
View File

@ -78,6 +78,25 @@ nlmsg_report_err_offset(struct nl_pstate *npt, uint32_t off)
return (true);
}
void
nlmsg_report_cookie(struct nl_pstate *npt, struct nlattr *nla)
{
MPASS(nla->nla_type == NLMSGERR_ATTR_COOKIE);
MPASS(nla->nla_len >= sizeof(struct nlattr));
npt->cookie = nla;
}
void
nlmsg_report_cookie_u32(struct nl_pstate *npt, uint32_t val)
{
struct nlattr *nla = npt_alloc(npt, sizeof(*nla) + sizeof(uint32_t));
nla->nla_type = NLMSGERR_ATTR_COOKIE;
nla->nla_len = sizeof(*nla) + sizeof(uint32_t);
memcpy(nla + 1, &val, sizeof(uint32_t));
nlmsg_report_cookie(npt, nla);
}
static const struct nlattr_parser *
search_states(const struct nlattr_parser *ps, int pslen, int key)
{

4
sys/netlink/netlink_message_parser.h
View File

@ -71,6 +71,7 @@ struct nl_pstate {
uint32_t err_off; /* error offset from hdr start */
int error; /* last operation error */
char *err_msg; /* Description of last error */
struct nlattr *cookie; /* NLA to return to the userspace */
bool strict; /* Strict parsing required */
};
@ -198,6 +199,9 @@ bool nlmsg_report_err_msg(struct nl_pstate *npt, const char *fmt, ...);
bool nlmsg_report_err_offset(struct nl_pstate *npt, uint32_t off);
void nlmsg_report_cookie(struct nl_pstate *npt, struct nlattr *nla);
void nlmsg_report_cookie_u32(struct nl_pstate *npt, uint32_t val);
/*
* Have it inline so compiler can optimize field accesses into
* the list of direct function calls without iteration.

6
sys/netlink/netlink_message_writer.c
View File

@ -643,10 +643,6 @@ nlmsg_ack(struct nlpcb *nlp, int error, struct nlmsghdr *hdr,
if ((npt->err_msg || npt->err_off) && nlp->nl_flags & NLF_EXT_ACK)
nl_flags |= NLM_F_ACK_TLVS;
/*
* TODO: handle cookies
*/
NL_LOG(LOG_DEBUG3, "acknowledging message type %d seq %d",
hdr->nlmsg_type, hdr->nlmsg_seq);
@ -662,6 +658,8 @@ nlmsg_ack(struct nlpcb *nlp, int error, struct nlmsghdr *hdr,
nlattr_add_string(nw, NLMSGERR_ATTR_MSG, npt->err_msg);
if (npt->err_off != 0 && nlp->nl_flags & NLF_EXT_ACK)
nlattr_add_u32(nw, NLMSGERR_ATTR_OFFS, npt->err_off);
if (npt->cookie != NULL)
nlattr_add_raw(nw, npt->cookie);
if (nlmsg_end(nw))
return;

31
sys/netlink/netlink_message_writer.h
View File

@ -163,6 +163,27 @@ _nlmsg_reserve_attr(struct nl_writer *nw, uint16_t nla_type, uint16_t sz)
}
#define nlmsg_reserve_attr(_ns, _at, _t) ((_t *)_nlmsg_reserve_attr(_ns, _at, NLA_ALIGN(sizeof(_t))))
static inline bool
nlattr_add_nla(struct nl_writer *nw, const struct nlattr *nla_src)
{
MPASS(nla_src->nla_len >= sizeof(struct nlattr));
int required_len = NLA_ALIGN(nla_src->nla_len);
if (__predict_false(nw->offset + required_len > nw->alloc_len)) {
if (!nlmsg_refill_buffer(nw, required_len))
return (false);
}
struct nlattr *nla = (struct nlattr *)(&nw->data[nw->offset]);
if ((nla_src->nla_len % 4) != 0) {
/* clear padding bytes */
bzero((char *)nla + nla_src->nla_len - 4, 4);
}
memcpy(nla, nla_src, nla_src->nla_len);
nw->offset += required_len;
return (true);
}
static inline bool
nlattr_add(struct nl_writer *nw, int attr_type, int attr_len, const void *data)
{
@ -188,6 +209,16 @@ nlattr_add(struct nl_writer *nw, int attr_type, int attr_len, const void *data)
return (true);
}
static inline bool
nlattr_add_raw(struct nl_writer *nw, const struct nlattr *nla_src)
{
int attr_len = nla_src->nla_len - sizeof(struct nlattr);
MPASS(attr_len >= 0);
return (nlattr_add(nw, nla_src->nla_type, attr_len, (const void *)(nla_src + 1)));
}
static inline bool
nlattr_add_u8(struct nl_writer *nw, int attrtype, uint8_t value)
{

37
sys/netlink/route/iface_drivers.c
View File

@ -109,6 +109,41 @@ modify_generic(struct ifnet *ifp, struct nl_parsed_link *lattrs,
return (0);
}
/*
* Saves the resulting ifindex and ifname to report them
* to userland along with the operation result.
* NLA format:
* NLMSGERR_ATTR_COOKIE(nested)
* IFLA_NEW_IFINDEX(u32)
* IFLA_IFNAME(string)
*/
static void
store_cookie(struct nl_pstate *npt, struct ifnet *ifp)
{
int ifname_len = strlen(if_name(ifp));
uint32_t ifindex = (uint32_t)ifp->if_index;
int nla_len = sizeof(struct nlattr) * 3 +
sizeof(ifindex) + NL_ITEM_ALIGN(ifname_len + 1);
struct nlattr *nla_cookie = npt_alloc(npt, nla_len);
/* Nested TLV */
nla_cookie->nla_len = nla_len;
nla_cookie->nla_type = NLMSGERR_ATTR_COOKIE;
struct nlattr *nla = nla_cookie + 1;
nla->nla_len = sizeof(struct nlattr) + sizeof(ifindex);
nla->nla_type = IFLA_NEW_IFINDEX;
memcpy(NLA_DATA(nla), &ifindex, sizeof(ifindex));
nla = NLA_NEXT(nla);
nla->nla_len = sizeof(struct nlattr) + ifname_len + 1;
nla->nla_type = IFLA_IFNAME;
strlcpy(NLA_DATA(nla), if_name(ifp), ifname_len + 1);
nlmsg_report_cookie(npt, nla_cookie);
}
/*
* Generic creation interface handler.
* Responsible for creating interfaces w/o parameters and setting
@ -135,6 +170,8 @@ create_generic(struct nl_parsed_link *lattrs, const struct nlattr_bmask *bm,
if (!success)
return (EINVAL);
error = modify_generic(ifp, lattrs, bm, nlp, npt);
if (error == 0)
store_cookie(npt, ifp);
if_rele(ifp);
}

126
tests/atf_python/sys/net/netlink.py
View File

@ -950,58 +950,68 @@ def prepare_attrs_map(attrs: List[AttrDescr]) -> Dict[str, Dict]:
return ret
rtnl_route_attrs = [
AttrDescr(RtattrType.RTA_DST, NlAttrIp),
AttrDescr(RtattrType.RTA_SRC, NlAttrIp),
AttrDescr(RtattrType.RTA_IIF, NlAttrIfindex),
AttrDescr(RtattrType.RTA_OIF, NlAttrIfindex),
AttrDescr(RtattrType.RTA_GATEWAY, NlAttrTable),
AttrDescr(RtattrType.RTA_VIA, NlAttrVia),
AttrDescr(RtattrType.RTA_NH_ID, NlAttrNhId),
AttrDescr(
RtattrType.RTA_METRICS,
NlAttrNested,
[
AttrDescr(NlRtaxType.RTAX_MTU, NlAttrU32),
],
),
]
rtnl_route_attrs = prepare_attrs_map(
[
AttrDescr(RtattrType.RTA_DST, NlAttrIp),
AttrDescr(RtattrType.RTA_SRC, NlAttrIp),
AttrDescr(RtattrType.RTA_IIF, NlAttrIfindex),
AttrDescr(RtattrType.RTA_OIF, NlAttrIfindex),
AttrDescr(RtattrType.RTA_GATEWAY, NlAttrTable),
AttrDescr(RtattrType.RTA_VIA, NlAttrVia),
AttrDescr(RtattrType.RTA_NH_ID, NlAttrNhId),
AttrDescr(
RtattrType.RTA_METRICS,
NlAttrNested,
[
AttrDescr(NlRtaxType.RTAX_MTU, NlAttrU32),
],
),
]
)
nldone_attrs = []
nldone_attrs = prepare_attrs_map([])
nlerr_attrs = [
AttrDescr(NlErrattrType.NLMSGERR_ATTR_MSG, NlAttrStr),
AttrDescr(NlErrattrType.NLMSGERR_ATTR_OFFS, NlAttrU32),
]
nlerr_attrs = prepare_attrs_map(
[
AttrDescr(NlErrattrType.NLMSGERR_ATTR_MSG, NlAttrStr),
AttrDescr(NlErrattrType.NLMSGERR_ATTR_OFFS, NlAttrU32),
AttrDescr(NlErrattrType.NLMSGERR_ATTR_COOKIE, NlAttr),
]
)
rtnl_ifla_attrs = [
AttrDescr(IflattrType.IFLA_ADDRESS, NlAttrMac),
AttrDescr(IflattrType.IFLA_BROADCAST, NlAttrMac),
AttrDescr(IflattrType.IFLA_IFNAME, NlAttrStr),
AttrDescr(IflattrType.IFLA_MTU, NlAttrU32),
AttrDescr(IflattrType.IFLA_PROMISCUITY, NlAttrU32),
AttrDescr(IflattrType.IFLA_OPERSTATE, NlAttrU8),
AttrDescr(IflattrType.IFLA_CARRIER, NlAttrU8),
AttrDescr(IflattrType.IFLA_IFALIAS, NlAttrStr),
AttrDescr(IflattrType.IFLA_STATS64, NlAttrIfStats),
AttrDescr(
IflattrType.IFLA_LINKINFO,
NlAttrNested,
[
AttrDescr(IflinkInfo.IFLA_INFO_KIND, NlAttrStr),
AttrDescr(IflinkInfo.IFLA_INFO_DATA, NlAttr),
],
),
]
rtnl_ifla_attrs = prepare_attrs_map(
[
AttrDescr(IflattrType.IFLA_ADDRESS, NlAttrMac),
AttrDescr(IflattrType.IFLA_BROADCAST, NlAttrMac),
AttrDescr(IflattrType.IFLA_IFNAME, NlAttrStr),
AttrDescr(IflattrType.IFLA_MTU, NlAttrU32),
AttrDescr(IflattrType.IFLA_PROMISCUITY, NlAttrU32),
AttrDescr(IflattrType.IFLA_OPERSTATE, NlAttrU8),
AttrDescr(IflattrType.IFLA_CARRIER, NlAttrU8),
AttrDescr(IflattrType.IFLA_IFALIAS, NlAttrStr),
AttrDescr(IflattrType.IFLA_STATS64, NlAttrIfStats),
AttrDescr(IflattrType.IFLA_NEW_IFINDEX, NlAttrU32),
AttrDescr(
IflattrType.IFLA_LINKINFO,
NlAttrNested,
[
AttrDescr(IflinkInfo.IFLA_INFO_KIND, NlAttrStr),
AttrDescr(IflinkInfo.IFLA_INFO_DATA, NlAttr),
],
),
]
)
rtnl_ifa_attrs = [
AttrDescr(IfattrType.IFA_ADDRESS, NlAttrIp),
AttrDescr(IfattrType.IFA_LOCAL, NlAttrIp),
AttrDescr(IfattrType.IFA_LABEL, NlAttrStr),
AttrDescr(IfattrType.IFA_BROADCAST, NlAttrIp),
AttrDescr(IfattrType.IFA_ANYCAST, NlAttrIp),
AttrDescr(IfattrType.IFA_FLAGS, NlAttrU32),
]
rtnl_ifa_attrs = prepare_attrs_map(
[
AttrDescr(IfattrType.IFA_ADDRESS, NlAttrIp),
AttrDescr(IfattrType.IFA_LOCAL, NlAttrIp),
AttrDescr(IfattrType.IFA_LABEL, NlAttrStr),
AttrDescr(IfattrType.IFA_BROADCAST, NlAttrIp),
AttrDescr(IfattrType.IFA_ANYCAST, NlAttrIp),
AttrDescr(IfattrType.IFA_FLAGS, NlAttrU32),
]
)
class BaseNetlinkMessage(object):
@ -1140,7 +1150,7 @@ def from_bytes(cls, helper, data):
raise
return self
def _parse_attrs(self, data: bytes, attr_map):
def parse_attrs(self, data: bytes, attr_map):
ret = []
off = 0
while len(data) - off >= 4:
@ -1157,7 +1167,7 @@ def _parse_attrs(self, data: bytes, attr_map):
val = v["ad"].cls.from_bytes(data[off : off + nla_len], v["ad"].val)
if "child" in v:
# nested
attrs, _ = self._parse_attrs(data[off : off + nla_len], v["child"])
attrs, _ = self.parse_attrs(data[off : off + nla_len], v["child"])
val = NlAttrNested(raw_nla_type, attrs)
else:
# unknown attribute
@ -1167,7 +1177,7 @@ def _parse_attrs(self, data: bytes, attr_map):
return ret, off
def parse_nla_list(self, data: bytes) -> List[NlAttr]:
return self._parse_attrs(data, self.nl_attrs_map)
return self.parse_attrs(data, self.nl_attrs_map)
def print_message(self):
self.print_nl_header(self.nl_hdr)
@ -1178,7 +1188,7 @@ def print_message(self):
class NetlinkDoneMessage(StdNetlinkMessage):
messages = [NlMsgType.NLMSG_DONE.value]
nl_attrs_map = prepare_attrs_map(nldone_attrs)
nl_attrs_map = nldone_attrs
@property
def error_code(self):
@ -1197,7 +1207,7 @@ def print_base_header(self, hdr, prepend=""):
class NetlinkErrorMessage(StdNetlinkMessage):
messages = [NlMsgType.NLMSG_ERROR.value]
nl_attrs_map = prepare_attrs_map(nlerr_attrs)
nl_attrs_map = nlerr_attrs
@property
def error_code(self):
@ -1217,6 +1227,10 @@ def error_offset(self):
return nla.u32
return None
@property
def cookie(self):
return self.get_nla(NlErrattrType.NLMSGERR_ATTR_COOKIE)
def parse_base_header(self, data):
if len(data) < sizeof(Nlmsgerr):
raise ValueError("length less than nlmsgerr header")
@ -1257,7 +1271,7 @@ class NetlinkRtMessage(BaseNetlinkRtMessage):
NlRtMsgType.RTM_DELROUTE.value,
NlRtMsgType.RTM_GETROUTE.value,
]
nl_attrs_map = prepare_attrs_map(rtnl_route_attrs)
nl_attrs_map = rtnl_route_attrs
def __init__(self, helper, nlm_type):
super().__init__(helper, nlm_type)
@ -1297,7 +1311,7 @@ class NetlinkIflaMessage(BaseNetlinkRtMessage):
NlRtMsgType.RTM_DELLINK.value,
NlRtMsgType.RTM_GETLINK.value,
]
nl_attrs_map = prepare_attrs_map(rtnl_ifla_attrs)
nl_attrs_map = rtnl_ifla_attrs
def __init__(self, helper, nlm_type):
super().__init__(helper, nlm_type)
@ -1329,7 +1343,7 @@ class NetlinkIfaMessage(BaseNetlinkRtMessage):
NlRtMsgType.RTM_DELADDR.value,
NlRtMsgType.RTM_GETADDR.value,
]
nl_attrs_map = prepare_attrs_map(rtnl_ifa_attrs)
nl_attrs_map = rtnl_ifa_attrs
def __init__(self, helper, nlm_type):
super().__init__(helper, nlm_type)

35
tests/sys/netlink/test_rtnl_iface.py
View File

@ -17,6 +17,7 @@
from atf_python.sys.net.netlink import NlmNewFlags
from atf_python.sys.net.netlink import NlMsgType
from atf_python.sys.net.netlink import NlRtMsgType
from atf_python.sys.net.netlink import rtnl_ifla_attrs
from atf_python.sys.net.vnet import SingleVnetTestTemplate
@ -91,6 +92,40 @@ def test_create_iface_plain(self):
self.get_interface_byname("lo10")
@pytest.mark.require_user("root")
def test_create_iface_plain_retvals(self):
"""Tests loopback creation w/o any parameters"""
flags = NlmNewFlags.NLM_F_EXCL.value | NlmNewFlags.NLM_F_CREATE.value
msg = NetlinkIflaMessage(self.helper, NlRtMsgType.RTM_NEWLINK.value)
msg.nl_hdr.nlmsg_flags = (
flags | NlmBaseFlags.NLM_F_ACK.value | NlmBaseFlags.NLM_F_REQUEST.value
)
msg.add_nla(NlAttrStr(IflattrType.IFLA_IFNAME, "lo10"))
msg.add_nla(
NlAttrNested(
IflattrType.IFLA_LINKINFO,
[
NlAttrStrn(IflinkInfo.IFLA_INFO_KIND, "lo"),
],
)
)
rx_msg = self.get_reply(msg)
assert rx_msg.is_type(NlMsgType.NLMSG_ERROR)
assert rx_msg.error_code == 0
assert rx_msg.cookie is not None
nla_list, _ = rx_msg.parse_attrs(bytes(rx_msg.cookie)[4:], rtnl_ifla_attrs)
nla_map = {n.nla_type: n for n in nla_list}
assert IflattrType.IFLA_IFNAME.value in nla_map
assert nla_map[IflattrType.IFLA_IFNAME.value].text == "lo10"
assert IflattrType.IFLA_NEW_IFINDEX.value in nla_map
assert nla_map[IflattrType.IFLA_NEW_IFINDEX.value].u32 > 0
lo_msg = self.get_interface_byname("lo10")
assert (
lo_msg.base_hdr.ifi_index == nla_map[IflattrType.IFLA_NEW_IFINDEX.value].u32
)
@pytest.mark.require_user("root")
def test_create_iface_attrs(self):
"""Tests interface creation with additional properties"""