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resolved: simplify error handling in manager_dns_stub_{udp,tcp}_fd()

Browse Source 
Make sure an error is always printed… When systemd-resolved is started in a
user namespace without private network, it would fail on setsockopt, but the
error wouldn't be particularly informative:
"Failed to start manager: permission denied."
This commit is contained in:
Zbigniew Jędrzejewski-Szmek 2016-10-09 14:19:06 -04:00
parent 084f580557
commit 424e490b94
2 changed files with 54 additions and 101 deletions
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152
src/resolve/resolved-dns-stub.c
View File

@ -25,6 +25,9 @@
* IP and UDP header sizes */
#define ADVERTISE_DATAGRAM_SIZE_MAX (65536U-14U-20U-8U)
static int manager_dns_stub_udp_fd(Manager *m);
static int manager_dns_stub_tcp_fd(Manager *m);
static int dns_stub_make_reply_packet(
uint16_t id,
int rcode,
@ -354,66 +357,48 @@ static int on_dns_stub_packet(sd_event_source *s, int fd, uint32_t revents, void
return 0;
}
int manager_dns_stub_udp_fd(Manager *m) {
static int manager_dns_stub_udp_fd(Manager *m) {
static const int one = 1;
union sockaddr_union sa = {
.in.sin_family = AF_INET,
.in.sin_port = htobe16(53),
.in.sin_addr.s_addr = htobe32(INADDR_DNS_STUB),
};
_cleanup_close_ int fd = -1;
int r;
if (m->dns_stub_udp_fd >= 0)
return m->dns_stub_udp_fd;
m->dns_stub_udp_fd = socket(AF_INET, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
if (m->dns_stub_udp_fd < 0)
fd = socket(AF_INET, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
if (fd < 0)
return -errno;
r = setsockopt(m->dns_stub_udp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
if (r < 0) {
r = -errno;
goto fail;
}
if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof one) < 0)
return -errno;
r = setsockopt(m->dns_stub_udp_fd, IPPROTO_IP, IP_PKTINFO, &one, sizeof(one));
if (r < 0) {
r = -errno;
goto fail;
}
if (setsockopt(fd, IPPROTO_IP, IP_PKTINFO, &one, sizeof one) < 0)
return -errno;
r = setsockopt(m->dns_stub_udp_fd, IPPROTO_IP, IP_RECVTTL, &one, sizeof(one));
if (r < 0) {
r = -errno;
goto fail;
}
if (setsockopt(fd, IPPROTO_IP, IP_RECVTTL, &one, sizeof one) < 0)
return -errno;
/* Make sure no traffic from outside the local host can leak to onto this socket */
r = setsockopt(m->dns_stub_udp_fd, SOL_SOCKET, SO_BINDTODEVICE, "lo", 3);
if (r < 0) {
r = -errno;
goto fail;
}
if (setsockopt(fd, SOL_SOCKET, SO_BINDTODEVICE, "lo", 3) < 0)
return -errno;
r = bind(m->dns_stub_udp_fd, &sa.sa, sizeof(sa.in));
if (r < 0) {
r = -errno;
goto fail;
}
if (bind(fd, &sa.sa, sizeof(sa.in)) < 0)
return -errno;
r = sd_event_add_io(m->event, &m->dns_stub_udp_event_source, m->dns_stub_udp_fd, EPOLLIN, on_dns_stub_packet, m);
r = sd_event_add_io(m->event, &m->dns_stub_udp_event_source, fd, EPOLLIN, on_dns_stub_packet, m);
if (r < 0)
goto fail;
return r;
(void) sd_event_source_set_description(m->dns_stub_udp_event_source, "dns-stub-udp");
m->dns_stub_udp_fd = fd;
fd = -1;
return m->dns_stub_udp_fd;
fail:
m->dns_stub_udp_fd = safe_close(m->dns_stub_udp_fd);
return r;
}
static int on_dns_stub_stream_packet(DnsStream *s) {
@ -461,106 +446,77 @@ static int on_dns_stub_stream(sd_event_source *s, int fd, uint32_t revents, void
return 0;
}
int manager_dns_stub_tcp_fd(Manager *m) {
static int manager_dns_stub_tcp_fd(Manager *m) {
static const int one = 1;
union sockaddr_union sa = {
.in.sin_family = AF_INET,
.in.sin_addr.s_addr = htobe32(INADDR_DNS_STUB),
.in.sin_port = htobe16(53),
};
_cleanup_close_ int fd = -1;
int r;
if (m->dns_stub_tcp_fd >= 0)
return m->dns_stub_tcp_fd;
m->dns_stub_tcp_fd = socket(AF_INET, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
if (m->dns_stub_tcp_fd < 0)
fd = socket(AF_INET, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
if (fd < 0)
return -errno;
r = setsockopt(m->dns_stub_tcp_fd, IPPROTO_IP, IP_TTL, &one, sizeof(one));
if (r < 0) {
r = -errno;
goto fail;
}
if (setsockopt(fd, IPPROTO_IP, IP_TTL, &one, sizeof one) < 0)
return -errno;
r = setsockopt(m->dns_stub_tcp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
if (r < 0) {
r = -errno;
goto fail;
}
if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof one) < 0)
return -errno;
r = setsockopt(m->dns_stub_tcp_fd, IPPROTO_IP, IP_PKTINFO, &one, sizeof(one));
if (r < 0) {
r = -errno;
goto fail;
}
if (setsockopt(fd, IPPROTO_IP, IP_PKTINFO, &one, sizeof one) < 0)
return -errno;
r = setsockopt(m->dns_stub_tcp_fd, IPPROTO_IP, IP_RECVTTL, &one, sizeof(one));
if (r < 0) {
r = -errno;
goto fail;
}
if (setsockopt(fd, IPPROTO_IP, IP_RECVTTL, &one, sizeof one) < 0)
return -errno;
/* Make sure no traffic from outside the local host can leak to onto this socket */
r = setsockopt(m->dns_stub_tcp_fd, SOL_SOCKET, SO_BINDTODEVICE, "lo", 3);
if (r < 0) {
r = -errno;
goto fail;
}
if (setsockopt(fd, SOL_SOCKET, SO_BINDTODEVICE, "lo", 3) < 0)
return -errno;
r = bind(m->dns_stub_tcp_fd, &sa.sa, sizeof(sa.in));
if (r < 0) {
r = -errno;
goto fail;
}
if (bind(fd, &sa.sa, sizeof(sa.in)) < 0)
return -errno;
r = listen(m->dns_stub_tcp_fd, SOMAXCONN);
if (r < 0) {
r = -errno;
goto fail;
}
if (listen(fd, SOMAXCONN) < 0)
return -errno;
r = sd_event_add_io(m->event, &m->dns_stub_tcp_event_source, m->dns_stub_tcp_fd, EPOLLIN, on_dns_stub_stream, m);
r = sd_event_add_io(m->event, &m->dns_stub_tcp_event_source, fd, EPOLLIN, on_dns_stub_stream, m);
if (r < 0)
goto fail;
return r;
(void) sd_event_source_set_description(m->dns_stub_tcp_event_source, "dns-stub-tcp");
m->dns_stub_tcp_fd = fd;
fd = -1;
return m->dns_stub_tcp_fd;
fail:
m->dns_stub_tcp_fd = safe_close(m->dns_stub_tcp_fd);
return r;
}
int manager_dns_stub_start(Manager *m) {
const char *t = "UDP";
int r;
assert(m);
if (IN_SET(m->dns_stub_listener_mode, DNS_STUB_LISTENER_YES, DNS_STUB_LISTENER_UDP)) {
if (IN_SET(m->dns_stub_listener_mode, DNS_STUB_LISTENER_YES, DNS_STUB_LISTENER_UDP))
r = manager_dns_stub_udp_fd(m);
if (r == -EADDRINUSE)
goto eaddrinuse;
if (r < 0)
return r;
}
if (IN_SET(m->dns_stub_listener_mode, DNS_STUB_LISTENER_YES, DNS_STUB_LISTENER_TCP)) {
if (r >= 0 &&
IN_SET(m->dns_stub_listener_mode, DNS_STUB_LISTENER_YES, DNS_STUB_LISTENER_TCP)) {
t = "TCP";
r = manager_dns_stub_tcp_fd(m);
if (r == -EADDRINUSE)
goto eaddrinuse;
if (r < 0)
return r;
}
return 0;
eaddrinuse:
log_warning("Another process is already listening on 127.0.0.53:53. Turning off local DNS stub support.");
manager_dns_stub_stop(m);
if (r == -EADDRINUSE) {
log_warning("Another process is already listening on %s socket 127.0.0.53:53.\n"
"Turning off local DNS stub support.", t);
manager_dns_stub_stop(m);
} else if (r < 0)
return log_error_errno(r, "Failed to listen on %s socket 127.0.0.53:53: %m", t);
return 0;
}

3
src/resolve/resolved-dns-stub.h
View File

@ -24,8 +24,5 @@
/* 127.0.0.53 in native endian */
#define INADDR_DNS_STUB ((in_addr_t) 0x7f000035U)
int manager_dns_stub_udp_fd(Manager *m);
int manager_dns_stub_tcp_fd(Manager *m);
void manager_dns_stub_stop(Manager *m);
int manager_dns_stub_start(Manager *m);