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netlink: Fill in netlink header fields from nl_req()

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Currently netlink functions need to fill in a full netlink header, as well
as a payload then call nl_req() to submit that to the kernel.  It makes
things a bit terser if we just give the relevant header fields as
parameters to nl_req() and have it complete the header.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
This commit is contained in:
David Gibson 2023-08-03 17:19:48 +10:00 committed by Stefano Brivio
parent f62600b2df
commit 282581ba84
1 changed files with 42 additions and 84 deletions
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126
netlink.c
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@ -97,25 +97,29 @@ fail:
}
/**
* nl_req() - Send netlink request and read response
* nl_req() - Prepare and send netlink request, read response
* @s: Netlink socket
* @buf: Buffer for response (at least NLBUFSIZ long)
* @req: Request with netlink header
* @req: Request (will fill netlink header)
* @type: Request type
* @flags: Extra request flags (NLM_F_REQUEST and NLM_F_ACK assumed)
* @len: Request length
*
* Return: received length on success, terminates on error
*/
static ssize_t nl_req(int s, char *buf, const void *req, ssize_t len)
static ssize_t nl_req(int s, char *buf, void *req,
uint16_t type, uint16_t flags, ssize_t len)
{
char flush[NLBUFSIZ];
struct nlmsghdr *nh;
int done = 0;
ssize_t n;
while (!done && (n = recv(s, flush, sizeof(flush), MSG_DONTWAIT)) > 0) {
struct nlmsghdr *nh = (struct nlmsghdr *)flush;
size_t nm = n;
for ( ; NLMSG_OK(nh, nm); nh = NLMSG_NEXT(nh, nm)) {
for (nh = (struct nlmsghdr *)flush;
NLMSG_OK(nh, nm); nh = NLMSG_NEXT(nh, nm)) {
if (nh->nlmsg_type == NLMSG_DONE ||
nh->nlmsg_type == NLMSG_ERROR) {
done = 1;
@ -124,6 +128,13 @@ static ssize_t nl_req(int s, char *buf, const void *req, ssize_t len)
}
}
nh = (struct nlmsghdr *)req;
nh->nlmsg_type = type;
nh->nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK | flags;
nh->nlmsg_len = len;
nh->nlmsg_seq = nl_seq++;
nh->nlmsg_pid = 0;
n = send(s, req, len, 0);
if (n < 0)
die("netlink: Failed to send(): %s", strerror(errno));
@ -148,11 +159,6 @@ static ssize_t nl_req(int s, char *buf, const void *req, ssize_t len)
unsigned int nl_get_ext_if(int s, sa_family_t af)
{
struct { struct nlmsghdr nlh; struct rtmsg rtm; } req = {
.nlh.nlmsg_type = RTM_GETROUTE,
.nlh.nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP,
.nlh.nlmsg_len = NLMSG_LENGTH(sizeof(struct rtmsg)),
.nlh.nlmsg_seq = nl_seq++,
.rtm.rtm_table = RT_TABLE_MAIN,
.rtm.rtm_scope = RT_SCOPE_UNIVERSE,
.rtm.rtm_type = RTN_UNICAST,
@ -164,7 +170,7 @@ unsigned int nl_get_ext_if(int s, sa_family_t af)
ssize_t n;
size_t na;
n = nl_req(s, buf, &req, sizeof(req));
n = nl_req(s, buf, &req, RTM_GETROUTE, NLM_F_DUMP, sizeof(req));
nh = (struct nlmsghdr *)buf;
@ -205,11 +211,6 @@ void nl_route_get_def(int s, unsigned int ifi, sa_family_t af, void *gw)
struct rtattr rta;
unsigned int ifi;
} req = {
.nlh.nlmsg_type = RTM_GETROUTE,
.nlh.nlmsg_len = sizeof(req),
.nlh.nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP,
.nlh.nlmsg_seq = nl_seq++,
.rtm.rtm_family = af,
.rtm.rtm_table = RT_TABLE_MAIN,
.rtm.rtm_scope = RT_SCOPE_UNIVERSE,
@ -223,7 +224,7 @@ void nl_route_get_def(int s, unsigned int ifi, sa_family_t af, void *gw)
char buf[NLBUFSIZ];
ssize_t n;
n = nl_req(s, buf, &req, req.nlh.nlmsg_len);
n = nl_req(s, buf, &req, RTM_GETROUTE, NLM_F_DUMP, sizeof(req));
for (nh = (struct nlmsghdr *)buf;
NLMSG_OK(nh, n) && nh->nlmsg_type != NLMSG_DONE;
@ -278,11 +279,6 @@ void nl_route_set_def(int s, unsigned int ifi, sa_family_t af, void *gw)
} r4;
} set;
} req = {
.nlh.nlmsg_type = RTM_NEWROUTE,
.nlh.nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK |
NLM_F_CREATE | NLM_F_EXCL,
.nlh.nlmsg_seq = nl_seq++,
.rtm.rtm_family = af,
.rtm.rtm_table = RT_TABLE_MAIN,
.rtm.rtm_scope = RT_SCOPE_UNIVERSE,
@ -294,12 +290,12 @@ void nl_route_set_def(int s, unsigned int ifi, sa_family_t af, void *gw)
.ifi = ifi,
};
char buf[NLBUFSIZ];
ssize_t len;
if (af == AF_INET6) {
size_t rta_len = RTA_LENGTH(sizeof(req.set.r6.d));
req.nlh.nlmsg_len = offsetof(struct req_t, set.r6)
+ sizeof(req.set.r6);
len = offsetof(struct req_t, set.r6) + sizeof(req.set.r6);
req.set.r6.rta_dst.rta_type = RTA_DST;
req.set.r6.rta_dst.rta_len = rta_len;
@ -310,8 +306,7 @@ void nl_route_set_def(int s, unsigned int ifi, sa_family_t af, void *gw)
} else {
size_t rta_len = RTA_LENGTH(sizeof(req.set.r4.d));
req.nlh.nlmsg_len = offsetof(struct req_t, set.r4)
+ sizeof(req.set.r4);
len = offsetof(struct req_t, set.r4) + sizeof(req.set.r4);
req.set.r4.rta_dst.rta_type = RTA_DST;
req.set.r4.rta_dst.rta_len = rta_len;
@ -321,7 +316,7 @@ void nl_route_set_def(int s, unsigned int ifi, sa_family_t af, void *gw)
req.set.r4.rta_gw.rta_len = rta_len;
}
nl_req(s, buf, &req, req.nlh.nlmsg_len);
nl_req(s, buf, &req, RTM_NEWROUTE, NLM_F_CREATE | NLM_F_EXCL, len);
}
/**
@ -341,11 +336,6 @@ void nl_route_dup(int s_src, unsigned int ifi_src,
struct rtattr rta;
unsigned int ifi;
} req = {
.nlh.nlmsg_type = RTM_GETROUTE,
.nlh.nlmsg_len = sizeof(req),
.nlh.nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP,
.nlh.nlmsg_seq = nl_seq++,
.rtm.rtm_family = af,
.rtm.rtm_table = RT_TABLE_MAIN,
.rtm.rtm_scope = RT_SCOPE_UNIVERSE,
@ -361,7 +351,8 @@ void nl_route_dup(int s_src, unsigned int ifi_src,
char buf[NLBUFSIZ];
unsigned i;
nlmsgs_size = nl_req(s_src, buf, &req, req.nlh.nlmsg_len);
nlmsgs_size = nl_req(s_src, buf, &req,
RTM_GETROUTE, NLM_F_DUMP, sizeof(req));
for (nh = (struct nlmsghdr *)buf, n = nlmsgs_size;
NLMSG_OK(nh, n) && nh->nlmsg_type != NLMSG_DONE;
@ -373,10 +364,6 @@ void nl_route_dup(int s_src, unsigned int ifi_src,
if (nh->nlmsg_type != RTM_NEWROUTE)
continue;
nh->nlmsg_pid = 0;
nh->nlmsg_flags &= ~NLM_F_DUMP_FILTERED;
nh->nlmsg_flags |= NLM_F_REQUEST | NLM_F_ACK |
NLM_F_CREATE;
dup_routes++;
for (rta = RTM_RTA(rtm), na = RTM_PAYLOAD(nh); RTA_OK(rta, na);
@ -397,13 +384,15 @@ void nl_route_dup(int s_src, unsigned int ifi_src,
for (nh = (struct nlmsghdr *)buf, n = nlmsgs_size;
NLMSG_OK(nh, n) && nh->nlmsg_type != NLMSG_DONE;
nh = NLMSG_NEXT(nh, n)) {
uint16_t flags = nh->nlmsg_flags;
char resp[NLBUFSIZ];
if (nh->nlmsg_type != RTM_NEWROUTE)
continue;
nh->nlmsg_seq = nl_seq++;
nl_req(s_dst, resp, nh, nh->nlmsg_len);
nl_req(s_dst, resp, nh, RTM_NEWROUTE,
(flags & ~NLM_F_DUMP_FILTERED) | NLM_F_CREATE,
nh->nlmsg_len);
}
}
}
@ -424,11 +413,6 @@ void nl_addr_get(int s, unsigned int ifi, sa_family_t af,
struct nlmsghdr nlh;
struct ifaddrmsg ifa;
} req = {
.nlh.nlmsg_type = RTM_GETADDR,
.nlh.nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK | NLM_F_DUMP,
.nlh.nlmsg_len = sizeof(req),
.nlh.nlmsg_seq = nl_seq++,
.ifa.ifa_family = af,
.ifa.ifa_index = ifi,
};
@ -436,7 +420,7 @@ void nl_addr_get(int s, unsigned int ifi, sa_family_t af,
char buf[NLBUFSIZ];
ssize_t n;
n = nl_req(s, buf, &req, req.nlh.nlmsg_len);
n = nl_req(s, buf, &req, RTM_GETADDR, NLM_F_DUMP, sizeof(req));
for (nh = (struct nlmsghdr *)buf;
NLMSG_OK(nh, n) && nh->nlmsg_type != NLMSG_DONE;
@ -500,18 +484,13 @@ void nl_addr_set(int s, unsigned int ifi, sa_family_t af,
} a6;
} set;
} req = {
.nlh.nlmsg_type = RTM_NEWADDR,
.nlh.nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK |
NLM_F_CREATE | NLM_F_EXCL,
.nlh.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifaddrmsg)),
.nlh.nlmsg_seq = nl_seq++,
.ifa.ifa_family = af,
.ifa.ifa_index = ifi,
.ifa.ifa_prefixlen = prefix_len,
.ifa.ifa_scope = RT_SCOPE_UNIVERSE,
};
char buf[NLBUFSIZ];
ssize_t len;
if (af == AF_INET6) {
size_t rta_len = RTA_LENGTH(sizeof(req.set.a6.l));
@ -519,8 +498,7 @@ void nl_addr_set(int s, unsigned int ifi, sa_family_t af,
/* By default, strictly speaking, it's duplicated */
req.ifa.ifa_flags = IFA_F_NODAD;
req.nlh.nlmsg_len = offsetof(struct req_t, set.a6)
+ sizeof(req.set.a6);
len = offsetof(struct req_t, set.a6) + sizeof(req.set.a6);
memcpy(&req.set.a6.l, addr, sizeof(req.set.a6.l));
req.set.a6.rta_l.rta_len = rta_len;
@ -531,8 +509,7 @@ void nl_addr_set(int s, unsigned int ifi, sa_family_t af,
} else {
size_t rta_len = RTA_LENGTH(sizeof(req.set.a4.l));
req.nlh.nlmsg_len = offsetof(struct req_t, set.a4)
+ sizeof(req.set.a4);
len = offsetof(struct req_t, set.a4) + sizeof(req.set.a4);
memcpy(&req.set.a4.l, addr, sizeof(req.set.a4.l));
req.set.a4.rta_l.rta_len = rta_len;
@ -541,7 +518,7 @@ void nl_addr_set(int s, unsigned int ifi, sa_family_t af,
req.set.a4.rta_a.rta_type = IFA_ADDRESS;
}
nl_req(s, buf, &req, req.nlh.nlmsg_len);
nl_req(s, buf, &req, RTM_NEWADDR, NLM_F_CREATE | NLM_F_EXCL, len);
}
/**
@ -559,11 +536,6 @@ void nl_addr_dup(int s_src, unsigned int ifi_src,
struct nlmsghdr nlh;
struct ifaddrmsg ifa;
} req = {
.nlh.nlmsg_type = RTM_GETADDR,
.nlh.nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP,
.nlh.nlmsg_len = sizeof(req),
.nlh.nlmsg_seq = nl_seq++,
.ifa.ifa_family = af,
.ifa.ifa_index = ifi_src,
.ifa.ifa_prefixlen = 0,
@ -572,7 +544,7 @@ void nl_addr_dup(int s_src, unsigned int ifi_src,
struct nlmsghdr *nh;
ssize_t n;
n = nl_req(s_src, buf, &req, sizeof(req));
n = nl_req(s_src, buf, &req, RTM_GETADDR, NLM_F_DUMP, sizeof(req));
for (nh = (struct nlmsghdr *)buf;
NLMSG_OK(nh, n) && nh->nlmsg_type != NLMSG_DONE;
@ -585,11 +557,6 @@ void nl_addr_dup(int s_src, unsigned int ifi_src,
if (nh->nlmsg_type != RTM_NEWADDR)
continue;
nh->nlmsg_seq = nl_seq++;
nh->nlmsg_pid = 0;
nh->nlmsg_flags &= ~NLM_F_DUMP_FILTERED;
nh->nlmsg_flags |= NLM_F_REQUEST | NLM_F_ACK | NLM_F_CREATE;
ifa = (struct ifaddrmsg *)NLMSG_DATA(nh);
if (ifa->ifa_scope == RT_SCOPE_LINK ||
@ -604,7 +571,9 @@ void nl_addr_dup(int s_src, unsigned int ifi_src,
rta->rta_type = IFA_UNSPEC;
}
nl_req(s_dst, resp, nh, nh->nlmsg_len);
nl_req(s_dst, resp, nh, RTM_NEWADDR,
(nh->nlmsg_flags & ~NLM_F_DUMP_FILTERED) | NLM_F_CREATE,
nh->nlmsg_len);
}
}
@ -620,10 +589,6 @@ void nl_link_get_mac(int s, unsigned int ifi, void *mac)
struct nlmsghdr nlh;
struct ifinfomsg ifm;
} req = {
.nlh.nlmsg_type = RTM_GETLINK,
.nlh.nlmsg_len = sizeof(req),
.nlh.nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK,
.nlh.nlmsg_seq = nl_seq++,
.ifm.ifi_family = AF_UNSPEC,
.ifm.ifi_index = ifi,
};
@ -631,7 +596,7 @@ void nl_link_get_mac(int s, unsigned int ifi, void *mac)
char buf[NLBUFSIZ];
ssize_t n;
n = nl_req(s, buf, &req, sizeof(req));
n = nl_req(s, buf, &req, RTM_GETLINK, 0, sizeof(req));
for (nh = (struct nlmsghdr *)buf;
NLMSG_OK(nh, n) && nh->nlmsg_type != NLMSG_DONE;
nh = NLMSG_NEXT(nh, n)) {
@ -669,10 +634,6 @@ void nl_link_set_mac(int s, unsigned int ifi, void *mac)
struct rtattr rta;
unsigned char mac[ETH_ALEN];
} req = {
.nlh.nlmsg_type = RTM_NEWLINK,
.nlh.nlmsg_len = sizeof(req),
.nlh.nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK,
.nlh.nlmsg_seq = nl_seq++,
.ifm.ifi_family = AF_UNSPEC,
.ifm.ifi_index = ifi,
.rta.rta_type = IFLA_ADDRESS,
@ -682,7 +643,7 @@ void nl_link_set_mac(int s, unsigned int ifi, void *mac)
memcpy(req.mac, mac, ETH_ALEN);
nl_req(s, buf, &req, sizeof(req));
nl_req(s, buf, &req, RTM_NEWLINK, 0, sizeof(req));
}
/**
@ -699,10 +660,6 @@ void nl_link_up(int s, unsigned int ifi, int mtu)
struct rtattr rta;
unsigned int mtu;
} req = {
.nlh.nlmsg_type = RTM_NEWLINK,
.nlh.nlmsg_len = sizeof(req),
.nlh.nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK,
.nlh.nlmsg_seq = nl_seq++,
.ifm.ifi_family = AF_UNSPEC,
.ifm.ifi_index = ifi,
.ifm.ifi_flags = IFF_UP,
@ -711,11 +668,12 @@ void nl_link_up(int s, unsigned int ifi, int mtu)
.rta.rta_len = RTA_LENGTH(sizeof(unsigned int)),
.mtu = mtu,
};
ssize_t len = sizeof(req);
char buf[NLBUFSIZ];
if (!mtu)
/* Shorten request to drop MTU attribute */
req.nlh.nlmsg_len = offsetof(struct req_t, rta);
len = offsetof(struct req_t, rta);
nl_req(s, buf, &req, req.nlh.nlmsg_len);
nl_req(s, buf, &req, RTM_NEWLINK, 0, len);
}