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Systemd/src/basic/socket-util.c
Franck Bui 10ce2e0681 socket-util: attempt SO_RCVBUFFORCE/SO_SNDBUFFORCE only if SO_RCVBUF/SO_SNDBUF fails 
Both SO_SNDBUFFORCE and SO_RCVBUFFORCE requires capability 'net_admin'.

If this capability is not granted to the service the first attempt to increase
the recv/snd buffers (via sd_notify()) with SO_RCVBUFFORCE/SO_SNDBUFFORCE will
fail, even if the requested size is lower than the limit enforced by the
kernel.

If apparmor is used, the DENIED logs for net_admin will show up. These log
entries are seen as red warning light, because they could indicate that a
program has been hacked and tries to compromise the system.

It would be nicer if they can be avoided without giving services (relying on
sd_notify) net_admin capability or dropping DENIED logs for all such services
via their apparmor profile.

I'm not sure if sd_notify really needs to forcibly increase the buffer sizes,
but at least if the requested size is below the kernel limit, the capability
(hence the log entries) should be avoided.

Hence let's first ask politely for increasing the buffers and only if it fails
then ignore the kernel limit if we have sufficient privileges.
2018-09-14 13:00:38 +02:00

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/* SPDX-License-Identifier: LGPL-2.1+ */
#include <arpa/inet.h>
#include <errno.h>
#include <limits.h>
#include <net/if.h>
#include <netdb.h>
#include <netinet/ip.h>
#include <poll.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "alloc-util.h"
#include "fd-util.h"
#include "fileio.h"
#include "format-util.h"
#include "log.h"
#include "macro.h"
#include "missing.h"
#include "parse-util.h"
#include "path-util.h"
#include "process-util.h"
#include "socket-util.h"
#include "string-table.h"
#include "string-util.h"
#include "strv.h"
#include "user-util.h"
#include "utf8.h"
#include "util.h"
#if ENABLE_IDN
# define IDN_FLAGS NI_IDN
#else
# define IDN_FLAGS 0
#endif
static const char* const socket_address_type_table[] = {
[SOCK_STREAM] = "Stream",
[SOCK_DGRAM] = "Datagram",
[SOCK_RAW] = "Raw",
[SOCK_RDM] = "ReliableDatagram",
[SOCK_SEQPACKET] = "SequentialPacket",
[SOCK_DCCP] = "DatagramCongestionControl",
};
DEFINE_STRING_TABLE_LOOKUP(socket_address_type, int);
int socket_address_parse(SocketAddress *a, const char *s) {
_cleanup_free_ char *n = NULL;
char *e;
int r;
assert(a);
assert(s);
zero(*a);
a->type = SOCK_STREAM;
if (*s == '[') {
uint16_t port;
/* IPv6 in [x:.....:z]:p notation */
e = strchr(s+1, ']');
if (!e)
return -EINVAL;
n = strndup(s+1, e-s-1);
if (!n)
return -ENOMEM;
errno = 0;
if (inet_pton(AF_INET6, n, &a->sockaddr.in6.sin6_addr) <= 0)
return errno > 0 ? -errno : -EINVAL;
e++;
if (*e != ':')
return -EINVAL;
e++;
r = parse_ip_port(e, &port);
if (r < 0)
return r;
a->sockaddr.in6.sin6_family = AF_INET6;
a->sockaddr.in6.sin6_port = htobe16(port);
a->size = sizeof(struct sockaddr_in6);
} else if (*s == '/') {
/* AF_UNIX socket */
size_t l;
l = strlen(s);
if (l >= sizeof(a->sockaddr.un.sun_path))
return -EINVAL;
a->sockaddr.un.sun_family = AF_UNIX;
memcpy(a->sockaddr.un.sun_path, s, l);
a->size = offsetof(struct sockaddr_un, sun_path) + l + 1;
} else if (*s == '@') {
/* Abstract AF_UNIX socket */
size_t l;
l = strlen(s+1);
if (l >= sizeof(a->sockaddr.un.sun_path) - 1)
return -EINVAL;
a->sockaddr.un.sun_family = AF_UNIX;
memcpy(a->sockaddr.un.sun_path+1, s+1, l);
a->size = offsetof(struct sockaddr_un, sun_path) + 1 + l;
} else if (startswith(s, "vsock:")) {
/* AF_VSOCK socket in vsock:cid:port notation */
const char *cid_start = s + STRLEN("vsock:");
unsigned port;
e = strchr(cid_start, ':');
if (!e)
return -EINVAL;
r = safe_atou(e+1, &port);
if (r < 0)
return r;
n = strndup(cid_start, e - cid_start);
if (!n)
return -ENOMEM;
if (!isempty(n)) {
r = safe_atou(n, &a->sockaddr.vm.svm_cid);
if (r < 0)
return r;
} else
a->sockaddr.vm.svm_cid = VMADDR_CID_ANY;
a->sockaddr.vm.svm_family = AF_VSOCK;
a->sockaddr.vm.svm_port = port;
a->size = sizeof(struct sockaddr_vm);
} else {
uint16_t port;
e = strchr(s, ':');
if (e) {
r = parse_ip_port(e + 1, &port);
if (r < 0)
return r;
n = strndup(s, e-s);
if (!n)
return -ENOMEM;
/* IPv4 in w.x.y.z:p notation? */
r = inet_pton(AF_INET, n, &a->sockaddr.in.sin_addr);
if (r < 0)
return -errno;
if (r > 0) {
/* Gotcha, it's a traditional IPv4 address */
a->sockaddr.in.sin_family = AF_INET;
a->sockaddr.in.sin_port = htobe16(port);
a->size = sizeof(struct sockaddr_in);
} else {
unsigned idx;
if (strlen(n) > IF_NAMESIZE-1)
return -EINVAL;
/* Uh, our last resort, an interface name */
idx = if_nametoindex(n);
if (idx == 0)
return -EINVAL;
a->sockaddr.in6.sin6_family = AF_INET6;
a->sockaddr.in6.sin6_port = htobe16(port);
a->sockaddr.in6.sin6_scope_id = idx;
a->sockaddr.in6.sin6_addr = in6addr_any;
a->size = sizeof(struct sockaddr_in6);
}
} else {
/* Just a port */
r = parse_ip_port(s, &port);
if (r < 0)
return r;
if (socket_ipv6_is_supported()) {
a->sockaddr.in6.sin6_family = AF_INET6;
a->sockaddr.in6.sin6_port = htobe16(port);
a->sockaddr.in6.sin6_addr = in6addr_any;
a->size = sizeof(struct sockaddr_in6);
} else {
a->sockaddr.in.sin_family = AF_INET;
a->sockaddr.in.sin_port = htobe16(port);
a->sockaddr.in.sin_addr.s_addr = INADDR_ANY;
a->size = sizeof(struct sockaddr_in);
}
}
}
return 0;
}
int socket_address_parse_and_warn(SocketAddress *a, const char *s) {
SocketAddress b;
int r;
/* Similar to socket_address_parse() but warns for IPv6 sockets when we don't support them. */
r = socket_address_parse(&b, s);
if (r < 0)
return r;
if (!socket_ipv6_is_supported() && b.sockaddr.sa.sa_family == AF_INET6) {
log_warning("Binding to IPv6 address not available since kernel does not support IPv6.");
return -EAFNOSUPPORT;
}
*a = b;
return 0;
}
int socket_address_parse_netlink(SocketAddress *a, const char *s) {
int family;
unsigned group = 0;
_cleanup_free_ char *sfamily = NULL;
assert(a);
assert(s);
zero(*a);
a->type = SOCK_RAW;
errno = 0;
if (sscanf(s, "%ms %u", &sfamily, &group) < 1)
return errno > 0 ? -errno : -EINVAL;
family = netlink_family_from_string(sfamily);
if (family < 0)
return -EINVAL;
a->sockaddr.nl.nl_family = AF_NETLINK;
a->sockaddr.nl.nl_groups = group;
a->type = SOCK_RAW;
a->size = sizeof(struct sockaddr_nl);
a->protocol = family;
return 0;
}
int socket_address_verify(const SocketAddress *a) {
assert(a);
switch (socket_address_family(a)) {
case AF_INET:
if (a->size != sizeof(struct sockaddr_in))
return -EINVAL;
if (a->sockaddr.in.sin_port == 0)
return -EINVAL;
if (!IN_SET(a->type, SOCK_STREAM, SOCK_DGRAM))
return -EINVAL;
return 0;
case AF_INET6:
if (a->size != sizeof(struct sockaddr_in6))
return -EINVAL;
if (a->sockaddr.in6.sin6_port == 0)
return -EINVAL;
if (!IN_SET(a->type, SOCK_STREAM, SOCK_DGRAM))
return -EINVAL;
return 0;
case AF_UNIX:
if (a->size < offsetof(struct sockaddr_un, sun_path))
return -EINVAL;
if (a->size > offsetof(struct sockaddr_un, sun_path)) {
if (a->sockaddr.un.sun_path[0] != 0) {
char *e;
/* path */
e = memchr(a->sockaddr.un.sun_path, 0, sizeof(a->sockaddr.un.sun_path));
if (!e)
return -EINVAL;
if (a->size != offsetof(struct sockaddr_un, sun_path) + (e - a->sockaddr.un.sun_path) + 1)
return -EINVAL;
}
}
if (!IN_SET(a->type, SOCK_STREAM, SOCK_DGRAM, SOCK_SEQPACKET))
return -EINVAL;
return 0;
case AF_NETLINK:
if (a->size != sizeof(struct sockaddr_nl))
return -EINVAL;
if (!IN_SET(a->type, SOCK_RAW, SOCK_DGRAM))
return -EINVAL;
return 0;
case AF_VSOCK:
if (a->size != sizeof(struct sockaddr_vm))
return -EINVAL;
if (!IN_SET(a->type, SOCK_STREAM, SOCK_DGRAM))
return -EINVAL;
return 0;
default:
return -EAFNOSUPPORT;
}
}
int socket_address_print(const SocketAddress *a, char **ret) {
int r;
assert(a);
assert(ret);
r = socket_address_verify(a);
if (r < 0)
return r;
if (socket_address_family(a) == AF_NETLINK) {
_cleanup_free_ char *sfamily = NULL;
r = netlink_family_to_string_alloc(a->protocol, &sfamily);
if (r < 0)
return r;
r = asprintf(ret, "%s %u", sfamily, a->sockaddr.nl.nl_groups);
if (r < 0)
return -ENOMEM;
return 0;
}
return sockaddr_pretty(&a->sockaddr.sa, a->size, false, true, ret);
}
bool socket_address_can_accept(const SocketAddress *a) {
assert(a);
return
IN_SET(a->type, SOCK_STREAM, SOCK_SEQPACKET);
}
bool socket_address_equal(const SocketAddress *a, const SocketAddress *b) {
assert(a);
assert(b);
/* Invalid addresses are unequal to all */
if (socket_address_verify(a) < 0 ||
socket_address_verify(b) < 0)
return false;
if (a->type != b->type)
return false;
if (socket_address_family(a) != socket_address_family(b))
return false;
switch (socket_address_family(a)) {
case AF_INET:
if (a->sockaddr.in.sin_addr.s_addr != b->sockaddr.in.sin_addr.s_addr)
return false;
if (a->sockaddr.in.sin_port != b->sockaddr.in.sin_port)
return false;
break;
case AF_INET6:
if (memcmp(&a->sockaddr.in6.sin6_addr, &b->sockaddr.in6.sin6_addr, sizeof(a->sockaddr.in6.sin6_addr)) != 0)
return false;
if (a->sockaddr.in6.sin6_port != b->sockaddr.in6.sin6_port)
return false;
break;
case AF_UNIX:
if (a->size <= offsetof(struct sockaddr_un, sun_path) ||
b->size <= offsetof(struct sockaddr_un, sun_path))
return false;
if ((a->sockaddr.un.sun_path[0] == 0) != (b->sockaddr.un.sun_path[0] == 0))
return false;
if (a->sockaddr.un.sun_path[0]) {
if (!path_equal_or_files_same(a->sockaddr.un.sun_path, b->sockaddr.un.sun_path, 0))
return false;
} else {
if (a->size != b->size)
return false;
if (memcmp(a->sockaddr.un.sun_path, b->sockaddr.un.sun_path, a->size) != 0)
return false;
}
break;
case AF_NETLINK:
if (a->protocol != b->protocol)
return false;
if (a->sockaddr.nl.nl_groups != b->sockaddr.nl.nl_groups)
return false;
break;
case AF_VSOCK:
if (a->sockaddr.vm.svm_cid != b->sockaddr.vm.svm_cid)
return false;
if (a->sockaddr.vm.svm_port != b->sockaddr.vm.svm_port)
return false;
break;
default:
/* Cannot compare, so we assume the addresses are different */
return false;
}
return true;
}
bool socket_address_is(const SocketAddress *a, const char *s, int type) {
struct SocketAddress b;
assert(a);
assert(s);
if (socket_address_parse(&b, s) < 0)
return false;
b.type = type;
return socket_address_equal(a, &b);
}
bool socket_address_is_netlink(const SocketAddress *a, const char *s) {
struct SocketAddress b;
assert(a);
assert(s);
if (socket_address_parse_netlink(&b, s) < 0)
return false;
return socket_address_equal(a, &b);
}
const char* socket_address_get_path(const SocketAddress *a) {
assert(a);
if (socket_address_family(a) != AF_UNIX)
return NULL;
if (a->sockaddr.un.sun_path[0] == 0)
return NULL;
return a->sockaddr.un.sun_path;
}
bool socket_ipv6_is_supported(void) {
if (access("/proc/net/if_inet6", F_OK) != 0)
return false;
return true;
}
bool socket_address_matches_fd(const SocketAddress *a, int fd) {
SocketAddress b;
socklen_t solen;
assert(a);
assert(fd >= 0);
b.size = sizeof(b.sockaddr);
if (getsockname(fd, &b.sockaddr.sa, &b.size) < 0)
return false;
if (b.sockaddr.sa.sa_family != a->sockaddr.sa.sa_family)
return false;
solen = sizeof(b.type);
if (getsockopt(fd, SOL_SOCKET, SO_TYPE, &b.type, &solen) < 0)
return false;
if (b.type != a->type)
return false;
if (a->protocol != 0) {
solen = sizeof(b.protocol);
if (getsockopt(fd, SOL_SOCKET, SO_PROTOCOL, &b.protocol, &solen) < 0)
return false;
if (b.protocol != a->protocol)
return false;
}
return socket_address_equal(a, &b);
}
int sockaddr_port(const struct sockaddr *_sa, unsigned *ret_port) {
union sockaddr_union *sa = (union sockaddr_union*) _sa;
/* Note, this returns the port as 'unsigned' rather than 'uint16_t', as AF_VSOCK knows larger ports */
assert(sa);
switch (sa->sa.sa_family) {
case AF_INET:
*ret_port = be16toh(sa->in.sin_port);
return 0;
case AF_INET6:
*ret_port = be16toh(sa->in6.sin6_port);
return 0;
case AF_VSOCK:
*ret_port = sa->vm.svm_port;
return 0;
default:
return -EAFNOSUPPORT;
}
}
int sockaddr_pretty(const struct sockaddr *_sa, socklen_t salen, bool translate_ipv6, bool include_port, char **ret) {
union sockaddr_union *sa = (union sockaddr_union*) _sa;
char *p;
int r;
assert(sa);
assert(salen >= sizeof(sa->sa.sa_family));
switch (sa->sa.sa_family) {
case AF_INET: {
uint32_t a;
a = be32toh(sa->in.sin_addr.s_addr);
if (include_port)
r = asprintf(&p,
"%u.%u.%u.%u:%u",
a >> 24, (a >> 16) & 0xFF, (a >> 8) & 0xFF, a & 0xFF,
be16toh(sa->in.sin_port));
else
r = asprintf(&p,
"%u.%u.%u.%u",
a >> 24, (a >> 16) & 0xFF, (a >> 8) & 0xFF, a & 0xFF);
if (r < 0)
return -ENOMEM;
break;
}
case AF_INET6: {
static const unsigned char ipv4_prefix[] = {
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xFF, 0xFF
};
if (translate_ipv6 &&
memcmp(&sa->in6.sin6_addr, ipv4_prefix, sizeof(ipv4_prefix)) == 0) {
const uint8_t *a = sa->in6.sin6_addr.s6_addr+12;
if (include_port)
r = asprintf(&p,
"%u.%u.%u.%u:%u",
a[0], a[1], a[2], a[3],
be16toh(sa->in6.sin6_port));
else
r = asprintf(&p,
"%u.%u.%u.%u",
a[0], a[1], a[2], a[3]);
if (r < 0)
return -ENOMEM;
} else {
char a[INET6_ADDRSTRLEN];
inet_ntop(AF_INET6, &sa->in6.sin6_addr, a, sizeof(a));
if (include_port) {
r = asprintf(&p,
"[%s]:%u",
a,
be16toh(sa->in6.sin6_port));
if (r < 0)
return -ENOMEM;
} else {
p = strdup(a);
if (!p)
return -ENOMEM;
}
}
break;
}
case AF_UNIX:
if (salen <= offsetof(struct sockaddr_un, sun_path)) {
p = strdup("<unnamed>");
if (!p)
return -ENOMEM;
} else if (sa->un.sun_path[0] == 0) {
/* abstract */
/* FIXME: We assume we can print the
* socket path here and that it hasn't
* more than one NUL byte. That is
* actually an invalid assumption */
p = new(char, sizeof(sa->un.sun_path)+1);
if (!p)
return -ENOMEM;
p[0] = '@';
memcpy(p+1, sa->un.sun_path+1, sizeof(sa->un.sun_path)-1);
p[sizeof(sa->un.sun_path)] = 0;
} else {
p = strndup(sa->un.sun_path, sizeof(sa->un.sun_path));
if (!p)
return -ENOMEM;
}
break;
case AF_VSOCK:
if (include_port)
r = asprintf(&p,
"vsock:%u:%u",
sa->vm.svm_cid,
sa->vm.svm_port);
else
r = asprintf(&p, "vsock:%u", sa->vm.svm_cid);
if (r < 0)
return -ENOMEM;
break;
default:
return -EOPNOTSUPP;
}
*ret = p;
return 0;
}
int getpeername_pretty(int fd, bool include_port, char **ret) {
union sockaddr_union sa;
socklen_t salen = sizeof(sa);
int r;
assert(fd >= 0);
assert(ret);
if (getpeername(fd, &sa.sa, &salen) < 0)
return -errno;
if (sa.sa.sa_family == AF_UNIX) {
struct ucred ucred = {};
/* UNIX connection sockets are anonymous, so let's use
* PID/UID as pretty credentials instead */
r = getpeercred(fd, &ucred);
if (r < 0)
return r;
if (asprintf(ret, "PID "PID_FMT"/UID "UID_FMT, ucred.pid, ucred.uid) < 0)
return -ENOMEM;
return 0;
}
/* For remote sockets we translate IPv6 addresses back to IPv4
* if applicable, since that's nicer. */
return sockaddr_pretty(&sa.sa, salen, true, include_port, ret);
}
int getsockname_pretty(int fd, char **ret) {
union sockaddr_union sa;
socklen_t salen = sizeof(sa);
assert(fd >= 0);
assert(ret);
if (getsockname(fd, &sa.sa, &salen) < 0)
return -errno;
/* For local sockets we do not translate IPv6 addresses back
* to IPv6 if applicable, since this is usually used for
* listening sockets where the difference between IPv4 and
* IPv6 matters. */
return sockaddr_pretty(&sa.sa, salen, false, true, ret);
}
int socknameinfo_pretty(union sockaddr_union *sa, socklen_t salen, char **_ret) {
int r;
char host[NI_MAXHOST], *ret;
assert(_ret);
r = getnameinfo(&sa->sa, salen, host, sizeof(host), NULL, 0, IDN_FLAGS);
if (r != 0) {
int saved_errno = errno;
r = sockaddr_pretty(&sa->sa, salen, true, true, &ret);
if (r < 0)
return r;
log_debug_errno(saved_errno, "getnameinfo(%s) failed: %m", ret);
} else {
ret = strdup(host);
if (!ret)
return -ENOMEM;
}
*_ret = ret;
return 0;
}
int socket_address_unlink(SocketAddress *a) {
assert(a);
if (socket_address_family(a) != AF_UNIX)
return 0;
if (a->sockaddr.un.sun_path[0] == 0)
return 0;
if (unlink(a->sockaddr.un.sun_path) < 0)
return -errno;
return 1;
}
static const char* const netlink_family_table[] = {
[NETLINK_ROUTE] = "route",
[NETLINK_FIREWALL] = "firewall",
[NETLINK_INET_DIAG] = "inet-diag",
[NETLINK_NFLOG] = "nflog",
[NETLINK_XFRM] = "xfrm",
[NETLINK_SELINUX] = "selinux",
[NETLINK_ISCSI] = "iscsi",
[NETLINK_AUDIT] = "audit",
[NETLINK_FIB_LOOKUP] = "fib-lookup",
[NETLINK_CONNECTOR] = "connector",
[NETLINK_NETFILTER] = "netfilter",
[NETLINK_IP6_FW] = "ip6-fw",
[NETLINK_DNRTMSG] = "dnrtmsg",
[NETLINK_KOBJECT_UEVENT] = "kobject-uevent",
[NETLINK_GENERIC] = "generic",
[NETLINK_SCSITRANSPORT] = "scsitransport",
[NETLINK_ECRYPTFS] = "ecryptfs",
[NETLINK_RDMA] = "rdma",
};
DEFINE_STRING_TABLE_LOOKUP_WITH_FALLBACK(netlink_family, int, INT_MAX);
static const char* const socket_address_bind_ipv6_only_table[_SOCKET_ADDRESS_BIND_IPV6_ONLY_MAX] = {
[SOCKET_ADDRESS_DEFAULT] = "default",
[SOCKET_ADDRESS_BOTH] = "both",
[SOCKET_ADDRESS_IPV6_ONLY] = "ipv6-only"
};
DEFINE_STRING_TABLE_LOOKUP(socket_address_bind_ipv6_only, SocketAddressBindIPv6Only);
SocketAddressBindIPv6Only socket_address_bind_ipv6_only_or_bool_from_string(const char *n) {
int r;
r = parse_boolean(n);
if (r > 0)
return SOCKET_ADDRESS_IPV6_ONLY;
if (r == 0)
return SOCKET_ADDRESS_BOTH;
return socket_address_bind_ipv6_only_from_string(n);
}
bool sockaddr_equal(const union sockaddr_union *a, const union sockaddr_union *b) {
assert(a);
assert(b);
if (a->sa.sa_family != b->sa.sa_family)
return false;
if (a->sa.sa_family == AF_INET)
return a->in.sin_addr.s_addr == b->in.sin_addr.s_addr;
if (a->sa.sa_family == AF_INET6)
return memcmp(&a->in6.sin6_addr, &b->in6.sin6_addr, sizeof(a->in6.sin6_addr)) == 0;
if (a->sa.sa_family == AF_VSOCK)
return a->vm.svm_cid == b->vm.svm_cid;
return false;
}
int fd_inc_sndbuf(int fd, size_t n) {
int r, value;
socklen_t l = sizeof(value);
r = getsockopt(fd, SOL_SOCKET, SO_SNDBUF, &value, &l);
if (r >= 0 && l == sizeof(value) && (size_t) value >= n*2)
return 0;
/* If we have the privileges we will ignore the kernel limit. */
value = (int) n;
if (setsockopt(fd, SOL_SOCKET, SO_SNDBUF, &value, sizeof(value)) < 0)
if (setsockopt(fd, SOL_SOCKET, SO_SNDBUFFORCE, &value, sizeof(value)) < 0)
return -errno;
return 1;
}
int fd_inc_rcvbuf(int fd, size_t n) {
int r, value;
socklen_t l = sizeof(value);
r = getsockopt(fd, SOL_SOCKET, SO_RCVBUF, &value, &l);
if (r >= 0 && l == sizeof(value) && (size_t) value >= n*2)
return 0;
/* If we have the privileges we will ignore the kernel limit. */
value = (int) n;
if (setsockopt(fd, SOL_SOCKET, SO_RCVBUF, &value, sizeof(value)) < 0)
if (setsockopt(fd, SOL_SOCKET, SO_RCVBUFFORCE, &value, sizeof(value)) < 0)
return -errno;
return 1;
}
static const char* const ip_tos_table[] = {
[IPTOS_LOWDELAY] = "low-delay",
[IPTOS_THROUGHPUT] = "throughput",
[IPTOS_RELIABILITY] = "reliability",
[IPTOS_LOWCOST] = "low-cost",
};
DEFINE_STRING_TABLE_LOOKUP_WITH_FALLBACK(ip_tos, int, 0xff);
bool ifname_valid(const char *p) {
bool numeric = true;
/* Checks whether a network interface name is valid. This is inspired by dev_valid_name() in the kernel sources
* but slightly stricter, as we only allow non-control, non-space ASCII characters in the interface name. We
* also don't permit names that only container numbers, to avoid confusion with numeric interface indexes. */
if (isempty(p))
return false;
if (strlen(p) >= IFNAMSIZ)
return false;
if (dot_or_dot_dot(p))
return false;
while (*p) {
if ((unsigned char) *p >= 127U)
return false;
if ((unsigned char) *p <= 32U)
return false;
if (IN_SET(*p, ':', '/'))
return false;
numeric = numeric && (*p >= '0' && *p <= '9');
p++;
}
if (numeric)
return false;
return true;
}
bool address_label_valid(const char *p) {
if (isempty(p))
return false;
if (strlen(p) >= IFNAMSIZ)
return false;
while (*p) {
if ((uint8_t) *p >= 127U)
return false;
if ((uint8_t) *p <= 31U)
return false;
p++;
}
return true;
}
int getpeercred(int fd, struct ucred *ucred) {
socklen_t n = sizeof(struct ucred);
struct ucred u;
int r;
assert(fd >= 0);
assert(ucred);
r = getsockopt(fd, SOL_SOCKET, SO_PEERCRED, &u, &n);
if (r < 0)
return -errno;
if (n != sizeof(struct ucred))
return -EIO;
/* Check if the data is actually useful and not suppressed due to namespacing issues */
if (!pid_is_valid(u.pid))
return -ENODATA;
/* Note that we don't check UID/GID here, as namespace translation works differently there: instead of
* receiving in "invalid" user/group we get the overflow UID/GID. */
*ucred = u;
return 0;
}
int getpeersec(int fd, char **ret) {
_cleanup_free_ char *s = NULL;
socklen_t n = 64;
assert(fd >= 0);
assert(ret);
for (;;) {
s = new0(char, n+1);
if (!s)
return -ENOMEM;
if (getsockopt(fd, SOL_SOCKET, SO_PEERSEC, s, &n) >= 0)
break;
if (errno != ERANGE)
return -errno;
s = mfree(s);
}
if (isempty(s))
return -EOPNOTSUPP;
*ret = TAKE_PTR(s);
return 0;
}
int getpeergroups(int fd, gid_t **ret) {
socklen_t n = sizeof(gid_t) * 64;
_cleanup_free_ gid_t *d = NULL;
assert(fd >= 0);
assert(ret);
for (;;) {
d = malloc(n);
if (!d)
return -ENOMEM;
if (getsockopt(fd, SOL_SOCKET, SO_PEERGROUPS, d, &n) >= 0)
break;
if (errno != ERANGE)
return -errno;
d = mfree(d);
}
assert_se(n % sizeof(gid_t) == 0);
n /= sizeof(gid_t);
if ((socklen_t) (int) n != n)
return -E2BIG;
*ret = TAKE_PTR(d);
return (int) n;
}
ssize_t send_one_fd_iov_sa(
int transport_fd,
int fd,
struct iovec *iov, size_t iovlen,
const struct sockaddr *sa, socklen_t len,
int flags) {
union {
struct cmsghdr cmsghdr;
uint8_t buf[CMSG_SPACE(sizeof(int))];
} control = {};
struct msghdr mh = {
.msg_name = (struct sockaddr*) sa,
.msg_namelen = len,
.msg_iov = iov,
.msg_iovlen = iovlen,
};
ssize_t k;
assert(transport_fd >= 0);
/*
* We need either an FD or data to send.
* If there's nothing, return an error.
*/
if (fd < 0 && !iov)
return -EINVAL;
if (fd >= 0) {
struct cmsghdr *cmsg;
mh.msg_control = &control;
mh.msg_controllen = sizeof(control);
cmsg = CMSG_FIRSTHDR(&mh);
cmsg->cmsg_level = SOL_SOCKET;
cmsg->cmsg_type = SCM_RIGHTS;
cmsg->cmsg_len = CMSG_LEN(sizeof(int));
memcpy(CMSG_DATA(cmsg), &fd, sizeof(int));
mh.msg_controllen = CMSG_SPACE(sizeof(int));
}
k = sendmsg(transport_fd, &mh, MSG_NOSIGNAL | flags);
if (k < 0)
return (ssize_t) -errno;
return k;
}
int send_one_fd_sa(
int transport_fd,
int fd,
const struct sockaddr *sa, socklen_t len,
int flags) {
assert(fd >= 0);
return (int) send_one_fd_iov_sa(transport_fd, fd, NULL, 0, sa, len, flags);
}
ssize_t receive_one_fd_iov(
int transport_fd,
struct iovec *iov, size_t iovlen,
int flags,
int *ret_fd) {
union {
struct cmsghdr cmsghdr;
uint8_t buf[CMSG_SPACE(sizeof(int))];
} control = {};
struct msghdr mh = {
.msg_control = &control,
.msg_controllen = sizeof(control),
.msg_iov = iov,
.msg_iovlen = iovlen,
};
struct cmsghdr *cmsg, *found = NULL;
ssize_t k;
assert(transport_fd >= 0);
assert(ret_fd);
/*
* Receive a single FD via @transport_fd. We don't care for
* the transport-type. We retrieve a single FD at most, so for
* packet-based transports, the caller must ensure to send
* only a single FD per packet. This is best used in
* combination with send_one_fd().
*/
k = recvmsg(transport_fd, &mh, MSG_CMSG_CLOEXEC | flags);
if (k < 0)
return (ssize_t) -errno;
CMSG_FOREACH(cmsg, &mh) {
if (cmsg->cmsg_level == SOL_SOCKET &&
cmsg->cmsg_type == SCM_RIGHTS &&
cmsg->cmsg_len == CMSG_LEN(sizeof(int))) {
assert(!found);
found = cmsg;
break;
}
}
if (!found)
cmsg_close_all(&mh);
/* If didn't receive an FD or any data, return an error. */
if (k == 0 && !found)
return -EIO;
if (found)
*ret_fd = *(int*) CMSG_DATA(found);
else
*ret_fd = -1;
return k;
}
int receive_one_fd(int transport_fd, int flags) {
int fd;
ssize_t k;
k = receive_one_fd_iov(transport_fd, NULL, 0, flags, &fd);
if (k == 0)
return fd;
/* k must be negative, since receive_one_fd_iov() only returns
* a positive value if data was received through the iov. */
assert(k < 0);
return (int) k;
}
ssize_t next_datagram_size_fd(int fd) {
ssize_t l;
int k;
/* This is a bit like FIONREAD/SIOCINQ, however a bit more powerful. The difference being: recv(MSG_PEEK) will
* actually cause the next datagram in the queue to be validated regarding checksums, which FIONREAD doesn't
* do. This difference is actually of major importance as we need to be sure that the size returned here
* actually matches what we will read with recvmsg() next, as otherwise we might end up allocating a buffer of
* the wrong size. */
l = recv(fd, NULL, 0, MSG_PEEK|MSG_TRUNC);
if (l < 0) {
if (IN_SET(errno, EOPNOTSUPP, EFAULT))
goto fallback;
return -errno;
}
if (l == 0)
goto fallback;
return l;
fallback:
k = 0;
/* Some sockets (AF_PACKET) do not support null-sized recv() with MSG_TRUNC set, let's fall back to FIONREAD
* for them. Checksums don't matter for raw sockets anyway, hence this should be fine. */
if (ioctl(fd, FIONREAD, &k) < 0)
return -errno;
return (ssize_t) k;
}
int flush_accept(int fd) {
struct pollfd pollfd = {
.fd = fd,
.events = POLLIN,
};
int r;
/* Similar to flush_fd() but flushes all incoming connection by accepting them and immediately closing them. */
for (;;) {
int cfd;
r = poll(&pollfd, 1, 0);
if (r < 0) {
if (errno == EINTR)
continue;
return -errno;
} else if (r == 0)
return 0;
cfd = accept4(fd, NULL, NULL, SOCK_NONBLOCK|SOCK_CLOEXEC);
if (cfd < 0) {
if (errno == EINTR)
continue;
if (errno == EAGAIN)
return 0;
return -errno;
}
close(cfd);
}
}
struct cmsghdr* cmsg_find(struct msghdr *mh, int level, int type, socklen_t length) {
struct cmsghdr *cmsg;
assert(mh);
CMSG_FOREACH(cmsg, mh)
if (cmsg->cmsg_level == level &&
cmsg->cmsg_type == type &&
(length == (socklen_t) -1 || length == cmsg->cmsg_len))
return cmsg;
return NULL;
}
int socket_ioctl_fd(void) {
int fd;
/* Create a socket to invoke the various network interface ioctl()s on. Traditionally only AF_INET was good for
* that. Since kernel 4.6 AF_NETLINK works for this too. We first try to use AF_INET hence, but if that's not
* available (for example, because it is made unavailable via SECCOMP or such), we'll fall back to the more
* generic AF_NETLINK. */
fd = socket(AF_INET, SOCK_DGRAM|SOCK_CLOEXEC, 0);
if (fd < 0)
fd = socket(AF_NETLINK, SOCK_RAW|SOCK_CLOEXEC, NETLINK_GENERIC);
if (fd < 0)
return -errno;
return fd;
}
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