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-rw-r--r--clientname.c538
1 files changed, 538 insertions, 0 deletions
diff --git a/clientname.c b/clientname.c
new file mode 100644
index 0000000..ea94894
--- /dev/null
+++ b/clientname.c
@@ -0,0 +1,538 @@
+/*
+ * Functions for looking up the remote name or addr of a socket.
+ *
+ * Copyright (C) 1992-2001 Andrew Tridgell <tridge@samba.org>
+ * Copyright (C) 2001, 2002 Martin Pool <mbp@samba.org>
+ * Copyright (C) 2002-2022 Wayne Davison
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, visit the http://fsf.org website.
+ */
+
+/*
+ * This file is now converted to use the new-style getaddrinfo()
+ * interface, which supports IPv6 but is also supported on recent
+ * IPv4-only machines. On systems that don't have that interface, we
+ * emulate it using the KAME implementation.
+ */
+
+#include "rsync.h"
+#include "itypes.h"
+
+extern int am_daemon;
+
+static const char default_name[] = "UNKNOWN";
+static const char proxyv2sig[] = "\r\n\r\n\0\r\nQUIT\n";
+
+static char ipaddr_buf[100];
+
+#define PROXY_V2_SIG_SIZE ((int)sizeof proxyv2sig - 1)
+#define PROXY_V2_HEADER_SIZE (PROXY_V2_SIG_SIZE + 1 + 1 + 2)
+
+#define CMD_LOCAL 0
+#define CMD_PROXY 1
+
+#define PROXY_FAM_TCPv4 0x11
+#define PROXY_FAM_TCPv6 0x21
+
+#define GET_SOCKADDR_FAMILY(ss) ((struct sockaddr*)ss)->sa_family
+
+static void client_sockaddr(int fd, struct sockaddr_storage *ss, socklen_t *ss_len);
+static int check_name(const char *ipaddr, const struct sockaddr_storage *ss, char *name_buf, size_t name_buf_size);
+static int valid_ipaddr(const char *s, int allow_scope);
+
+/* Return the IP addr of the client as a string. */
+char *client_addr(int fd)
+{
+ struct sockaddr_storage ss;
+ socklen_t length = sizeof ss;
+
+ if (*ipaddr_buf)
+ return ipaddr_buf;
+
+ if (am_daemon < 0) { /* daemon over --rsh mode */
+ char *env_str;
+ strlcpy(ipaddr_buf, "0.0.0.0", sizeof ipaddr_buf);
+ if ((env_str = getenv("REMOTE_HOST")) != NULL
+ || (env_str = getenv("SSH_CONNECTION")) != NULL
+ || (env_str = getenv("SSH_CLIENT")) != NULL
+ || (env_str = getenv("SSH2_CLIENT")) != NULL) {
+ char *p;
+ strlcpy(ipaddr_buf, env_str, sizeof ipaddr_buf);
+ /* Truncate the value to just the IP address. */
+ if ((p = strchr(ipaddr_buf, ' ')) != NULL)
+ *p = '\0';
+ }
+ if (valid_ipaddr(ipaddr_buf, True))
+ return ipaddr_buf;
+ }
+
+ client_sockaddr(fd, &ss, &length);
+ getnameinfo((struct sockaddr *)&ss, length, ipaddr_buf, sizeof ipaddr_buf, NULL, 0, NI_NUMERICHOST);
+
+ return ipaddr_buf;
+}
+
+
+/**
+ * Return the DNS name of the client.
+ *
+ * The name is statically cached so that repeated lookups are quick,
+ * so there is a limit of one lookup per customer.
+ *
+ * If anything goes wrong, including the name->addr->name check, then
+ * we just use "UNKNOWN", so you can use that value in hosts allow
+ * lines.
+ *
+ * After translation from sockaddr to name we do a forward lookup to
+ * make sure nobody is spoofing PTR records.
+ **/
+char *client_name(const char *ipaddr)
+{
+ static char name_buf[100];
+ char port_buf[100];
+ struct sockaddr_storage ss;
+ socklen_t ss_len;
+ struct addrinfo hint, *answer;
+ int err;
+
+ if (*name_buf)
+ return name_buf;
+
+ strlcpy(name_buf, default_name, sizeof name_buf);
+
+ if (strcmp(ipaddr, "0.0.0.0") == 0)
+ return name_buf;
+
+ memset(&ss, 0, sizeof ss);
+ memset(&hint, 0, sizeof hint);
+
+#ifdef AI_NUMERICHOST
+ hint.ai_flags = AI_NUMERICHOST;
+#endif
+ hint.ai_socktype = SOCK_STREAM;
+
+ if ((err = getaddrinfo(ipaddr, NULL, &hint, &answer)) != 0) {
+ rprintf(FLOG, "malformed address %s: %s\n", ipaddr, gai_strerror(err));
+ return name_buf;
+ }
+
+ switch (answer->ai_family) {
+ case AF_INET:
+ ss_len = sizeof (struct sockaddr_in);
+ memcpy(&ss, answer->ai_addr, ss_len);
+ break;
+#ifdef INET6
+ case AF_INET6:
+ ss_len = sizeof (struct sockaddr_in6);
+ memcpy(&ss, answer->ai_addr, ss_len);
+ break;
+#endif
+ default:
+ NOISY_DEATH("Unknown ai_family value");
+ }
+ freeaddrinfo(answer);
+
+ /* reverse lookup */
+ err = getnameinfo((struct sockaddr*)&ss, ss_len, name_buf, sizeof name_buf,
+ port_buf, sizeof port_buf, NI_NAMEREQD | NI_NUMERICSERV);
+ if (err) {
+ strlcpy(name_buf, default_name, sizeof name_buf);
+ rprintf(FLOG, "name lookup failed for %s: %s\n", ipaddr, gai_strerror(err));
+ } else
+ check_name(ipaddr, &ss, name_buf, sizeof name_buf);
+
+ return name_buf;
+}
+
+
+/* Try to read a proxy protocol header (V1 or V2). Returns 1 on success or 0 on failure. */
+int read_proxy_protocol_header(int fd)
+{
+ union {
+ struct {
+ char line[108];
+ } v1;
+ struct {
+ char sig[PROXY_V2_SIG_SIZE];
+ char ver_cmd;
+ char fam;
+ char len[2];
+ union {
+ struct {
+ char src_addr[4];
+ char dst_addr[4];
+ char src_port[2];
+ char dst_port[2];
+ } ip4;
+ struct {
+ char src_addr[16];
+ char dst_addr[16];
+ char src_port[2];
+ char dst_port[2];
+ } ip6;
+ struct {
+ char src_addr[108];
+ char dst_addr[108];
+ } unx;
+ } addr;
+ } v2;
+ } hdr;
+
+ read_buf(fd, (char*)&hdr, PROXY_V2_SIG_SIZE);
+
+ if (memcmp(hdr.v2.sig, proxyv2sig, PROXY_V2_SIG_SIZE) == 0) { /* Proxy V2 */
+ int ver, cmd, size;
+
+ read_buf(fd, (char*)&hdr + PROXY_V2_SIG_SIZE, PROXY_V2_HEADER_SIZE - PROXY_V2_SIG_SIZE);
+
+ ver = (hdr.v2.ver_cmd & 0xf0) >> 4;
+ cmd = (hdr.v2.ver_cmd & 0x0f);
+ size = (hdr.v2.len[0] << 8) + hdr.v2.len[1];
+
+ if (ver != 2 || size + PROXY_V2_HEADER_SIZE > (int)sizeof hdr)
+ return 0;
+
+ /* Grab all the remaining data in the binary request. */
+ read_buf(fd, (char*)&hdr + PROXY_V2_HEADER_SIZE, size);
+
+ switch (cmd) {
+ case CMD_PROXY:
+ switch (hdr.v2.fam) {
+ case PROXY_FAM_TCPv4:
+ if (size != sizeof hdr.v2.addr.ip4)
+ return 0;
+ inet_ntop(AF_INET, hdr.v2.addr.ip4.src_addr, ipaddr_buf, sizeof ipaddr_buf);
+ return valid_ipaddr(ipaddr_buf, False);
+#ifdef INET6
+ case PROXY_FAM_TCPv6:
+ if (size != sizeof hdr.v2.addr.ip6)
+ return 0;
+ inet_ntop(AF_INET6, hdr.v2.addr.ip6.src_addr, ipaddr_buf, sizeof ipaddr_buf);
+ return valid_ipaddr(ipaddr_buf, False);
+#endif
+ default:
+ break;
+ }
+ /* For an unsupported protocol we'll ignore the proxy data (leaving ipaddr_buf unset)
+ * and accept the connection, which will get handled as a normal socket addr. */
+ return 1;
+ case CMD_LOCAL:
+ return 1;
+ default:
+ break;
+ }
+
+ return 0;
+ }
+
+ if (memcmp(hdr.v1.line, "PROXY", 5) == 0) { /* Proxy V1 */
+ char *endc, *sp, *p = hdr.v1.line + PROXY_V2_SIG_SIZE;
+ int port_chk;
+
+ *p = '\0';
+ if (!strchr(hdr.v1.line, '\n')) {
+ while (1) {
+ read_buf(fd, p, 1);
+ if (*p++ == '\n')
+ break;
+ if (p - hdr.v1.line >= (int)sizeof hdr.v1.line - 1)
+ return 0;
+ }
+ *p = '\0';
+ }
+
+ endc = strchr(hdr.v1.line, '\r');
+ if (!endc || endc[1] != '\n' || endc[2])
+ return 0;
+ *endc = '\0';
+
+ p = hdr.v1.line + 5;
+
+ if (!isSpace(p++))
+ return 0;
+ if (strncmp(p, "TCP4", 4) == 0)
+ p += 4;
+ else if (strncmp(p, "TCP6", 4) == 0)
+ p += 4;
+ else if (strncmp(p, "UNKNOWN", 7) == 0)
+ return 1;
+ else
+ return 0;
+
+ if (!isSpace(p++))
+ return 0;
+
+ if ((sp = strchr(p, ' ')) == NULL)
+ return 0;
+ *sp = '\0';
+ if (!valid_ipaddr(p, False))
+ return 0;
+ strlcpy(ipaddr_buf, p, sizeof ipaddr_buf); /* It will always fit when valid. */
+
+ p = sp + 1;
+ if ((sp = strchr(p, ' ')) == NULL)
+ return 0;
+ *sp = '\0';
+ if (!valid_ipaddr(p, False))
+ return 0;
+ /* Ignore destination address. */
+
+ p = sp + 1;
+ if ((sp = strchr(p, ' ')) == NULL)
+ return 0;
+ *sp = '\0';
+ port_chk = strtol(p, &endc, 10);
+ if (*endc || port_chk == 0)
+ return 0;
+ /* Ignore source port. */
+
+ p = sp + 1;
+ port_chk = strtol(p, &endc, 10);
+ if (*endc || port_chk == 0)
+ return 0;
+ /* Ignore destination port. */
+
+ return 1;
+ }
+
+ return 0;
+}
+
+
+/**
+ * Get the sockaddr for the client.
+ *
+ * If it comes in as an ipv4 address mapped into IPv6 format then we
+ * convert it back to a regular IPv4.
+ **/
+static void client_sockaddr(int fd, struct sockaddr_storage *ss, socklen_t *ss_len)
+{
+ memset(ss, 0, sizeof *ss);
+
+ if (getpeername(fd, (struct sockaddr *) ss, ss_len)) {
+ /* FIXME: Can we really not continue? */
+ rsyserr(FLOG, errno, "getpeername on fd%d failed", fd);
+ exit_cleanup(RERR_SOCKETIO);
+ }
+
+#ifdef INET6
+ if (GET_SOCKADDR_FAMILY(ss) == AF_INET6
+ && IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)ss)->sin6_addr)) {
+ /* OK, so ss is in the IPv6 family, but it is really
+ * an IPv4 address: something like
+ * "::ffff:10.130.1.2". If we use it as-is, then the
+ * reverse lookup might fail or perhaps something else
+ * bad might happen. So instead we convert it to an
+ * equivalent address in the IPv4 address family. */
+ struct sockaddr_in6 sin6;
+ struct sockaddr_in *sin;
+
+ memcpy(&sin6, ss, sizeof sin6);
+ sin = (struct sockaddr_in *)ss;
+ memset(sin, 0, sizeof *sin);
+ sin->sin_family = AF_INET;
+ *ss_len = sizeof (struct sockaddr_in);
+#ifdef HAVE_SOCKADDR_IN_LEN
+ sin->sin_len = *ss_len;
+#endif
+ sin->sin_port = sin6.sin6_port;
+
+ /* There is a macro to extract the mapped part
+ * (IN6_V4MAPPED_TO_SINADDR ?), but it does not seem
+ * to be present in the Linux headers. */
+ memcpy(&sin->sin_addr, &sin6.sin6_addr.s6_addr[12], sizeof sin->sin_addr);
+ }
+#endif
+}
+
+
+/**
+ * Compare an addrinfo from the resolver to a sockinfo.
+ *
+ * Like strcmp, returns 0 for identical.
+ **/
+static int compare_addrinfo_sockaddr(const struct addrinfo *ai, const struct sockaddr_storage *ss)
+{
+ int ss_family = GET_SOCKADDR_FAMILY(ss);
+ const char fn[] = "compare_addrinfo_sockaddr";
+
+ if (ai->ai_family != ss_family) {
+ rprintf(FLOG, "%s: response family %d != %d\n",
+ fn, ai->ai_family, ss_family);
+ return 1;
+ }
+
+ /* The comparison method depends on the particular AF. */
+ if (ss_family == AF_INET) {
+ const struct sockaddr_in *sin1, *sin2;
+
+ sin1 = (const struct sockaddr_in *) ss;
+ sin2 = (const struct sockaddr_in *) ai->ai_addr;
+
+ return memcmp(&sin1->sin_addr, &sin2->sin_addr, sizeof sin1->sin_addr);
+ }
+
+#ifdef INET6
+ if (ss_family == AF_INET6) {
+ const struct sockaddr_in6 *sin1, *sin2;
+
+ sin1 = (const struct sockaddr_in6 *) ss;
+ sin2 = (const struct sockaddr_in6 *) ai->ai_addr;
+
+ if (ai->ai_addrlen < (int)sizeof (struct sockaddr_in6)) {
+ rprintf(FLOG, "%s: too short sockaddr_in6; length=%d\n",
+ fn, (int)ai->ai_addrlen);
+ return 1;
+ }
+
+ if (memcmp(&sin1->sin6_addr, &sin2->sin6_addr, sizeof sin1->sin6_addr))
+ return 1;
+
+#ifdef HAVE_SOCKADDR_IN6_SCOPE_ID
+ if (sin1->sin6_scope_id != sin2->sin6_scope_id)
+ return 1;
+#endif
+ return 0;
+ }
+#endif /* INET6 */
+
+ /* don't know */
+ return 1;
+}
+
+
+/**
+ * Do a forward lookup on @p name_buf and make sure it corresponds to
+ * @p ss -- otherwise we may be being spoofed. If we suspect we are,
+ * then we don't abort the connection but just emit a warning, and
+ * change @p name_buf to be "UNKNOWN".
+ *
+ * We don't do anything with the service when checking the name,
+ * because it doesn't seem that it could be spoofed in any way, and
+ * getaddrinfo on random service names seems to cause problems on AIX.
+ **/
+static int check_name(const char *ipaddr, const struct sockaddr_storage *ss, char *name_buf, size_t name_buf_size)
+{
+ struct addrinfo hints, *res, *res0;
+ int error;
+ int ss_family = GET_SOCKADDR_FAMILY(ss);
+
+ memset(&hints, 0, sizeof hints);
+ hints.ai_family = ss_family;
+ hints.ai_flags = AI_CANONNAME;
+ hints.ai_socktype = SOCK_STREAM;
+ error = getaddrinfo(name_buf, NULL, &hints, &res0);
+ if (error) {
+ rprintf(FLOG, "forward name lookup for %s failed: %s\n",
+ name_buf, gai_strerror(error));
+ strlcpy(name_buf, default_name, name_buf_size);
+ return error;
+ }
+
+ /* Given all these results, we expect that one of them will be
+ * the same as ss. The comparison is a bit complicated. */
+ for (res = res0; res; res = res->ai_next) {
+ if (!compare_addrinfo_sockaddr(res, ss))
+ break; /* OK, identical */
+ }
+
+ if (!res0) {
+ /* We hit the end of the list without finding an
+ * address that was the same as ss. */
+ rprintf(FLOG, "no known address for \"%s\": "
+ "spoofed address?\n", name_buf);
+ strlcpy(name_buf, default_name, name_buf_size);
+ } else if (res == NULL) {
+ /* We hit the end of the list without finding an
+ * address that was the same as ss. */
+ rprintf(FLOG, "%s is not a known address for \"%s\": "
+ "spoofed address?\n", ipaddr, name_buf);
+ strlcpy(name_buf, default_name, name_buf_size);
+ }
+
+ freeaddrinfo(res0);
+ return 0;
+}
+
+/* Returns 1 for a valid IPv4 or IPv6 addr, or 0 for a bad one. */
+static int valid_ipaddr(const char *s, int allow_scope)
+{
+ int i;
+
+ if (strchr(s, ':') != NULL) { /* Only IPv6 has a colon. */
+ int count, saw_double_colon = 0;
+ int ipv4_at_end = 0;
+
+ if (*s == ':') { /* A colon at the start must be a :: */
+ if (*++s != ':')
+ return 0;
+ saw_double_colon = 1;
+ s++;
+ }
+
+ for (count = 0; count < 8; count++) {
+ if (!*s)
+ return saw_double_colon;
+ if (allow_scope && *s == '%') {
+ if (saw_double_colon)
+ break;
+ return 0;
+ }
+
+ if (strchr(s, ':') == NULL && strchr(s, '.') != NULL) {
+ if ((!saw_double_colon && count != 6) || (saw_double_colon && count > 6))
+ return 0;
+ ipv4_at_end = 1;
+ break;
+ }
+
+ if (!isHexDigit(s++)) /* Need 1-4 hex digits */
+ return 0;
+ if (isHexDigit(s) && isHexDigit(++s) && isHexDigit(++s) && isHexDigit(++s))
+ return 0;
+
+ if (*s == ':') {
+ if (!*++s)
+ return 0;
+ if (*s == ':') {
+ if (saw_double_colon)
+ return 0;
+ saw_double_colon = 1;
+ s++;
+ }
+ }
+ }
+
+ if (!ipv4_at_end) {
+ if (allow_scope && *s == '%')
+ for (s++; isAlNum(s); s++) { }
+ return !*s && s[-1] != '%';
+ }
+ }
+
+ /* IPv4 */
+ for (i = 0; i < 4; i++) {
+ long n;
+ char *end;
+
+ if (i && *s++ != '.')
+ return 0;
+ n = strtol(s, &end, 10);
+ if (n > 255 || n < 0 || end <= s || end > s+3)
+ return 0;
+ s = end;
+ }
+
+ return !*s;
+}
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