--- /dev/null
+.de VS
+.sp 1
+.RS
+.nf
+.ft B
+..
+.de VE
+.ft R
+.fi
+.RE
+.sp 1
+..
+.TH noip 1 "5 May 2005" "Straylight/Edgeware" "Preload hacks"
+.SH NAME
+noip \- run programs without the ability to use IP sockets
+.SH SYNOPSIS
+.B noip
+.RI [ command
+.RI [ args ...]]
+.SH DESCRIPTION
+The
+.B noip
+program runs
+.I command
+(by default, the user's shell, as determined by the
+.B SHELL
+environment variable) in an environment where attempts to use TCP/IP
+networking are (mostly) transparently translated into the use of
+Unix-domain sockets in a private directory.
+.PP
+There are many programs which use TCP/IP for their own internal
+communications needs, largely unnecessarily. This can present security
+problems: even if a program binds its listening sockets to
+.BR localhost ,
+other users on the same system can still connect, and many such programs
+don't seem to have authentication systems.
+.PP
+.B noip
+addresses this problem by intercepting a program's networking calls and
+making it use Unix-domain sockets in a private directory instead of
+TCP/IP. Now its communications are truly private to the running user.
+.SS The socket directory
+The
+.B noip
+program keeps its sockets in a directory whose name can be configured,
+but by default is
+.BI noip- \c
+.IR username ,
+where
+.I username
+is determined by the
+.B USER
+or
+.B LOGNAME
+environment variables, or is
+.BI uid- \c
+.IR realuid
+in the temporary directory, which in turn is determined by the
+.B TMPDIR
+or
+.B TMP
+environment variables, or is
+.BR /tmp .
+The sockets in this directory are simply named
+.IB dottedquad : port
+after the Internet sockets they represent.
+.PP
+If the socket directory does not exist when a program running under
+.B noip
+starts up, it is created and made readable and writable only by the
+current user. Also, it is scanned and any apparently stale sockets are
+removed.
+.SS Configuration
+The operation of
+.B noip
+is controlled by a configuration file. By default,
+.B noip
+reads configuration from
+.B .noip
+in the calling user's home directory, as determined by the
+.B HOME
+environment, or, failing that, looking up the
+.I real
+(not effective) user id in the password database.
+.PP
+The configuration file has a simple line-based format. A line is
+ignored if it consists only of whitespace, or if its first whitespace
+character is
+.RB ` # '.
+Otherwise, the first whitespace-delimited word is a keyword and the
+remainder of the line is a value. The following keywords are
+recognized.
+.TP
+.BR "debug " [\fInumber\fR]
+If
+.I number
+is nonzero, turn debugging on; if it is zero, turn debugging off. The
+default, if no
+.I number
+is given, is to turn debugging on. Debugging is written to standard
+error. Some debugging is produced before the configuration file is
+read; the environment variable
+.B NOIP_DEBUG
+can be used to control this.
+.TP
+.BI "socketdir " directory
+Store the Unix-domain sockets in
+.IR directory
+rather than the default.
+.TP
+.BI "realbind " acl-entry
+Add an entry to the
+.B realbind
+access control list (ACL). When a program attempts to
+.BR bind (2)
+a socket to an address, the
+.B realbind
+ACL is consulted. If the address is matched, then the program is
+allowed to bind a real Internet socket to that address; otherwise, the
+socket is bound to a Unix-domain socket.
+.TP
+.BI "realbind " acl-entry
+Add an entry to the
+.B realconnect
+access control list (ACL). When a program attempts to
+.BR connect (2)
+a socket to an address, or to contact another socket using
+.BR sendto (2)
+or
+.BR sendmsg (2),
+the
+.B realconnect
+ACL is consulted. If the destination address is matched, then the
+program is allowed to contact the real Internet socket; otherwise, the
+attempt is made to contact a Unix-domain socket.
+.PP
+(Aside: An attempt to connect to a remote host may not be a hopeless failure,
+even if a real IP socket is denied:
+.B noip
+deliberately makes no attempt to check that addresses being bound to
+sockets correspond to locally available addresses; and besides, sockets
+can be introduced into the directory by other programs simulating remote
+servers.)
+.PP
+An
+.I acl-entry
+has this format:
+.IP
+.BR + | \-
+.IR address \c
+.RB [ \- \c
+.IR address | \c
+.BR / \c
+.IR mask ]| \c
+.BR local | any
+.RB [ : \c
+.IR port [ \c
+.BI \- \c
+.IR port ]]
+.PP
+(The spaces in the above are optional.)
+.PP
+The leading sign says whether
+matching addresses should be
+.I accepted
+.RB (` + ')
+or
+.I denied
+.RB (` \- ').
+.PP
+The IP-address portion may be any of the following
+.TP
+.B any
+Matches all addresses.
+.TP
+.B local
+Matches the address of one of the machine's network interfaces.
+.TP
+.I address
+Matches just the given address
+.TP
+.IB address \- address
+Matches any address which falls in the given range. Addresses are
+compared lexicographically, with octets to the left given precedence
+over octets to the right.
+.TP
+.IB address / mask
+Matches an address in the given network. The
+.I mask
+may be a netmask in dotted-quad form, or a one-bit-count.
+.PP
+The port portion may be omitted (which means `match any port'), or may
+be a single
+.I port
+or a range
+.IB port \- port
+to match.
+.PP
+Range comparisons are always inclusive of both endpoints.
+.PP
+ACL entries are processed in the order they appear in the configuration
+file. The default action of an ACL, used if none of its entries match,
+is the opposite of the last actual entry in the list: if the last entry
+says `accept', then the default is to deny, and vice-versa. If the ACL
+is empty, the default is to deny all addresses.
+.PP
+For example, it may be useful to allow access at least to a DNS server.
+This can be accomplished by adding a line
+.VS
+realconnect +1.2.3.4:52
+.VE
+to the configuration file, where 1.2.3.4 is the IP address of one of
+your DNS server.
+.SS Example applications
+SLIME is an Emacs extension for doing interactive programming with Lisp
+systems. It communicates with the Lisp system using TCP sockets, since
+Unix-domain sockets are unavailable on Windows, and besides, they are
+less well supported by Lisp implementations. Unfortunately, when the
+author wrote this program, SLIME applied no authentication on its TCP
+port, allowing any local user to take over the running Lisp. Worse,
+some Lisps are unable to bind a listening socket to a particular
+address, leaving the socket potentially available to anyone on the
+network. By running Emacs under
+.BR noip ,
+the security hole is closed completely and no messing with
+authentication secrets is needed.
+.PP
+SSH is an excellent tool for secure communications over hostile
+networks. In particular, its ability to forward TCP connections to a
+port on one side of an SSH tunnel to the other side is very useful.
+However, such a forwarded port is available to all users on the source
+side of the tunnel. Using
+.B noip
+and a suitable configuration, a user can restrict access to a forwarded
+port to himself or a small group.
+.SH BUGS
+.B noip
+is implemented as an
+.B LD_PRELOAD
+hack. It won't work on setuid programs. Also, perhaps more
+importantly, it can't do anything a
+.I malicious
+program use of networking: a program could theoretically issue sockets
+system calls directly instead of using the C library calls that
+.B noip
+intercepts. It is intended only as a tool for enhancing the security of
+software written by well-meaning programmers who don't understand the
+security aspects of writing networking code.
+.PP
+It's very hard to tell exactly what state a Unix-domain socket is in.
+If the filesystem object isn't there, it's not active, but if it
+.I is
+then the socket might be in use or it might be stale.
+.B noip
+consults
+.B /proc/net/unix
+to decide whether a socket is in use, but this can fail in two ways.
+Firstly, if the socket is created and renamed, the kernel doesn't
+notice, and
+.B noip
+will think that the new name is stale. Secondly, if the socket is
+created, used, unlinked while it's still in use, and recreated, then
+.B noip
+will think that it's in use when in fact it's gone stale. Don't mess
+with
+.BR noip 's
+sockets unless you know what you're doing.
+.PP
+The procedure to replace a Unix-domain socket by an Internet one is
+fairly thorough, but there are some missing cases. In particular, if
+the socket being bound or connected is a duplicate (using
+.BR dup (2))
+then only one of the copies will be fixed. Similarly, copies owned by
+child processes will be unaffected.
+.PP
+This manual is surprisingly long and complicated for such a simple hack.
+.SH AUTHOR
+Mark Wooding, <mdw@nsict.org>
--- /dev/null
+#define _GNU_SOURCE
+#undef sun
+#undef SUN
+#define DEBUG
+
+#include <ctype.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#include <unistd.h>
+#include <dirent.h>
+#include <dlfcn.h>
+#include <fcntl.h>
+#include <pwd.h>
+
+#include <sys/ioctl.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/un.h>
+
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <netinet/tcp.h>
+#include <netinet/udp.h>
+#include <net/if.h>
+
+enum { UNUSED, STALE, USED };
+enum { WANT_FRESH, WANT_EXISTING };
+enum { DENY, ALLOW };
+typedef struct aclnode {
+ struct aclnode *next;
+ int act;
+ unsigned long minaddr, maxaddr;
+ unsigned short minport, maxport;
+} aclnode;
+
+#define MAX_LOCAL_IPADDRS 16
+static struct in_addr local_ipaddrs[MAX_LOCAL_IPADDRS];
+static int n_local_ipaddrs;
+
+static uid_t uid;
+static char *sockdir = 0;
+static int debug = 0;
+
+static aclnode *bind_real, **bind_tail = &bind_real;
+static aclnode *connect_real, **connect_tail = &connect_real;
+
+/* --- Import magic --- */
+
+#define IMPORTS(_) \
+ _(socket, int, (int, int, int)) \
+ _(socketpair, int, (int, int, int, int *)) \
+ _(connect, int, (int, const struct sockaddr *, socklen_t)) \
+ _(bind, int, (int, const struct sockaddr *, socklen_t)) \
+ _(accept, int, (int, struct sockaddr *, socklen_t *)) \
+ _(getsockname, int, (int, struct sockaddr *, socklen_t *)) \
+ _(getpeername, int, (int, struct sockaddr *, socklen_t *)) \
+ _(getsockopt, int, (int, int, int, void *, socklen_t *)) \
+ _(setsockopt, int, (int, int, int, const void *, socklen_t)) \
+ _(sendto, ssize_t, (int, const void *buf, size_t, int, \
+ const struct sockaddr *to, socklen_t tolen)) \
+ _(recvfrom, ssize_t, (int, void *buf, size_t, int, \
+ struct sockaddr *from, socklen_t *fromlen)) \
+ _(sendmsg, ssize_t, (int, const struct msghdr *, int)) \
+ _(recvmsg, ssize_t, (int, struct msghdr *, int)) \
+ _(close, int, (int))
+
+#define DECL(imp, ret, args) static ret (*real_##imp) args;
+IMPORTS(DECL)
+#undef DECL
+
+static void setup(void) __attribute__((constructor));
+static void import(void)
+{
+#define IMPORT(imp, ret, args) \
+ real_##imp = (ret (*)args)dlsym(RTLD_NEXT, #imp);
+ IMPORTS(IMPORT)
+#undef IMPORT
+}
+
+/* --- Support --- */
+
+#define SA(sa) ((struct sockaddr *)(sa))
+#define SIN(sa) ((struct sockaddr_in *)(sa))
+#define SUN(sa) ((struct sockaddr_un *)(sa))
+
+#define UC(ch) ((unsigned char)(ch))
+
+#define NEW(x) ((x) = xmalloc(sizeof(*x)))
+#define NEWV(x, n) ((x) = xmalloc(sizeof(*x) * (n)))
+
+#ifdef DEBUG
+# define D(body) { if (debug) { body } }
+#else
+# define D(body) ;
+#endif
+
+#define PRESERVING_ERRNO(body) do { \
+ int _err = errno; { body } errno = _err; \
+} while (0)
+
+static void *xmalloc(size_t n)
+{
+ void *p;
+ if (!n) return (0);
+ if ((p = malloc(n)) == 0) { perror("malloc"); exit(1); }
+ return (p);
+}
+
+static char *xstrdup(const char *p)
+{
+ size_t n = strlen(p) + 1;
+ char *q = xmalloc(n);
+ memcpy(q, p, n);
+ return (q);
+}
+
+static int unix_socket_status(struct sockaddr_un *sun, int quick_p)
+{
+ struct stat st;
+ FILE *fp = 0;
+ size_t len, n;
+ int rc;
+ char buf[256];
+
+ rc = UNUSED;
+ if (stat(sun->sun_path, &st) && errno == ENOENT)
+ goto done;
+ rc = USED;
+ if (quick_p)
+ goto done;
+
+ if ((fp = fopen("/proc/net/unix", "r")) == 0)
+ goto done;
+ fgets(buf, sizeof(buf), fp); /* skip header */
+ len = strlen(sun->sun_path);
+ while (fgets(buf, sizeof(buf), fp)) {
+ n = strlen(buf);
+ if (n >= len + 2 && buf[n - len - 2] == ' ' && buf[n - 1] == '\n' &&
+ memcmp(buf + n - len - 1, sun->sun_path, len) == 0)
+ goto done;
+ }
+ if (ferror(fp))
+ goto done;
+ rc = STALE;
+done:
+ if (fp) fclose(fp);
+ return (rc);
+}
+
+#ifdef DEBUG
+
+static void dump_aclnode(aclnode *a)
+{
+ char minbuf[16], maxbuf[16];
+ struct in_addr amin, amax;
+
+ amin.s_addr = htonl(a->minaddr);
+ amax.s_addr = htonl(a->maxaddr);
+ fprintf(stderr, "noip: %c ", a->act ? '+' : '-');
+ if (a->minaddr == 0 && a->maxaddr == 0xffffffff)
+ fprintf(stderr, "any");
+ else {
+ fprintf(stderr, "%s",
+ inet_ntop(AF_INET, &amin, minbuf, sizeof(minbuf)));
+ if (a->maxaddr != a->minaddr) {
+ fprintf(stderr, "-%s",
+ inet_ntop(AF_INET, &amax, maxbuf, sizeof(maxbuf)));
+ }
+ }
+ if (a->minport != 0 || a->maxport != 0xffff) {
+ fprintf(stderr, ":%u", (unsigned)a->minport);
+ if (a->minport != a->maxport)
+ fprintf(stderr, "-%u", (unsigned)a->maxport);
+ }
+ fputc('\n', stderr);
+}
+
+#endif
+
+static int acl_allows_p(aclnode *a, const struct sockaddr_in *sin)
+{
+ unsigned long addr = ntohl(sin->sin_addr.s_addr);
+ unsigned short port = ntohs(sin->sin_port);
+ int act = ALLOW;
+
+ D( char buf[16];
+ fprintf(stderr, "noip: check %s:%u\n",
+ inet_ntop(AF_INET, &sin->sin_addr, buf, sizeof(buf)),
+ ntohs((unsigned)sin->sin_port)); )
+ for (; a; a = a->next) {
+ D( dump_aclnode(a); )
+ if (a->minaddr <= addr && addr <= a->maxaddr &&
+ a->minport <= port && port <= a->maxport) {
+ D( fprintf(stderr, "noip: aha! %s\n", a->act ? "ALLOW" : "DENY"); )
+ return (a->act);
+ }
+ act = a->act;
+ }
+ D( fprintf(stderr, "noip: nothing found: %s\n", act ? "DENY" : "ALLOW"); )
+ return (!act);
+}
+
+#ifdef DEBUG
+
+static void dump_acl(aclnode *a)
+{
+ int act = ALLOW;
+
+ for (; a; a = a->next) {
+ dump_aclnode(a);
+ act = a->act;
+ }
+ fprintf(stderr, "noip: [default policy: %s]\n",
+ act == ALLOW ? "DENY" : "ALLOW");
+}
+
+#endif
+
+static int encode_inet_addr(struct sockaddr_un *sun,
+ const struct sockaddr_in *sin,
+ int want)
+{
+ int i;
+ int desperate_p = 0;
+ char buf[INET_ADDRSTRLEN];
+ int rc;
+
+ D( fprintf(stderr, "noip: encode %s:%u (%s)",
+ inet_ntop(AF_INET, &sin->sin_addr, buf, sizeof(buf)),
+ (unsigned)ntohs(sin->sin_port),
+ want == WANT_EXISTING ? "EXISTING" : "FRESH"); )
+ sun->sun_family = AF_UNIX;
+ if (sin->sin_port || want == WANT_EXISTING) {
+ snprintf(sun->sun_path, sizeof(sun->sun_path), "%s/%s:%u", sockdir,
+ inet_ntop(AF_INET, &sin->sin_addr, buf, sizeof(buf)),
+ (unsigned)ntohs(sin->sin_port));
+ rc = unix_socket_status(sun, 0);
+ if (rc == STALE) unlink(sun->sun_path);
+ if (rc != USED && want == WANT_EXISTING) {
+ snprintf(sun->sun_path, sizeof(sun->sun_path), "%s/0.0.0.0:%u",
+ sockdir, (unsigned)ntohs(sin->sin_port));
+ if (unix_socket_status(sun, 0) == STALE) unlink(sun->sun_path);
+ }
+ } else {
+ for (desperate_p = 0; desperate_p < 2; desperate_p++) {
+ for (i = 16384; i < 65536; i++) {
+ snprintf(sun->sun_path, sizeof(sun->sun_path), "%s/%s:%u", sockdir,
+ inet_ntop(AF_INET, &sin->sin_addr, buf, sizeof(buf)),
+ (unsigned)i);
+ rc = unix_socket_status(sun, !desperate_p);
+ switch (rc) {
+ case STALE: unlink(sun->sun_path);
+ case UNUSED: goto found;
+ }
+ }
+ }
+ errno = EADDRINUSE;
+ D( fprintf(stderr, " -- can't resolve\n"); )
+ return (-1);
+ found:;
+ }
+ D( fprintf(stderr, " -> `%s'\n", sun->sun_path); )
+ return (0);
+}
+
+static int decode_inet_addr(struct sockaddr_in *sin,
+ const struct sockaddr_un *sun,
+ socklen_t len)
+{
+ char buf[INET_ADDRSTRLEN + 16];
+ char *p;
+ size_t n = strlen(sockdir), nn = strlen(sun->sun_path);
+ struct sockaddr_in sin_mine;
+ unsigned long port;
+
+ if (!sin)
+ sin = &sin_mine;
+ if (sun->sun_family != AF_UNIX)
+ return (-1);
+ if (len < sizeof(sun)) ((char *)sun)[len] = 0;
+ D( fprintf(stderr, "noip: decode (%d) `%s'",
+ *sun->sun_path, sun->sun_path); )
+ if (!sun->sun_path[0]) {
+ sin->sin_family = AF_INET;
+ sin->sin_addr.s_addr = INADDR_ANY;
+ sin->sin_port = 0;
+ D( fprintf(stderr, " -- unbound socket\n"); )
+ return (0);
+ }
+ if (nn < n + 1 || nn - n >= sizeof(buf) || sun->sun_path[n] != '/' ||
+ memcmp(sun->sun_path, sockdir, n) != 0) {
+ D( fprintf(stderr, " -- not one of ours\n"); )
+ return (-1);
+ }
+ memcpy(buf, sun->sun_path + n + 1, nn - n);
+ if ((p = strchr(buf, ':')) == 0) {
+ D( fprintf(stderr, " -- malformed (no port)\n"); )
+ return (-1);
+ }
+ *p++ = 0;
+ sin->sin_family = AF_INET;
+ if (inet_pton(AF_INET, buf, &sin->sin_addr) <= 0) {
+ D( fprintf(stderr, " -- malformed (bad address `%s')\n", buf); )
+ return (-1);
+ }
+ port = strtoul(p, &p, 10);
+ if (*p || port >= 65536) {
+ D( fprintf(stderr, " -- malformed (port out of range)"); )
+ return (-1);
+ }
+ sin->sin_port = htons(port);
+ D( fprintf(stderr, " -> %s:%u\n",
+ inet_ntop(AF_INET, &sin->sin_addr, buf, sizeof(buf)),
+ (unsigned)port); )
+ return (0);
+}
+
+static int fixup_real_ip_socket(int sk)
+{
+ int nsk;
+ int type;
+ int f, fd;
+ struct sockaddr_un sun;
+ struct sockaddr_in sin;
+ socklen_t len;
+
+#define OPTS(_) \
+ _(DEBUG, int) \
+ _(REUSEADDR, int) \
+ _(DONTROUTE, int) \
+ _(BROADCAST, int) \
+ _(SNDBUF, int) \
+ _(RCVBUF, int) \
+ _(OOBINLINE, int) \
+ _(NO_CHECK, int) \
+ _(LINGER, struct linger) \
+ _(BSDCOMPAT, int) \
+ _(RCVLOWAT, int) \
+ _(RCVTIMEO, struct timeval) \
+ _(SNDTIMEO, struct timeval)
+
+ len = sizeof(sun);
+ if (real_getsockname(sk, SA(&sun), &len))
+ return (-1);
+ if (decode_inet_addr(&sin, &sun, len))
+ return (0); /* Not one of ours */
+ len = sizeof(type);
+ if (real_getsockopt(sk, SOL_SOCKET, SO_TYPE, &type, &len) < 0 ||
+ (nsk = real_socket(PF_INET, type, 0)) < 0)
+ return (-1);
+#define FIX(opt, ty) do { \
+ ty ov_; \
+ len = sizeof(ov_); \
+ if (real_getsockopt(sk, SOL_SOCKET, SO_##opt, &ov_, &len) < 0 || \
+ real_setsockopt(nsk, SOL_SOCKET, SO_##opt, &ov_, len)) { \
+ real_close(nsk); \
+ return (-1); \
+ } \
+} while (0);
+ OPTS(FIX)
+#undef FIX
+ if ((f = fcntl(sk, F_GETFL)) < 0 ||
+ (fd = fcntl(sk, F_GETFD)) < 0 ||
+ fcntl(nsk, F_SETFL, f) < 0 ||
+ dup2(nsk, sk) < 0) {
+ real_close(nsk);
+ return (-1);
+ }
+ unlink(sun.sun_path);
+ real_close(nsk);
+ if (fcntl(sk, F_SETFD, fd) < 0) {
+ perror("noip: fixup_real_ip_socket F_SETFD");
+ abort();
+ }
+ return (0);
+}
+
+static int do_implicit_bind(int sk, const struct sockaddr **sa,
+ socklen_t *len, struct sockaddr_un *sun)
+{
+ struct sockaddr_in sin;
+ socklen_t mylen = sizeof(*sun);
+
+ if (acl_allows_p(connect_real, SIN(*sa))) {
+ if (fixup_real_ip_socket(sk))
+ return (-1);
+ } else {
+ if (real_getsockname(sk, SA(sun), &mylen) < 0)
+ return (-1);
+ if (sun->sun_family == AF_UNIX) {
+ if (mylen < sizeof(*sun)) ((char *)sun)[mylen] = 0;
+ if (!sun->sun_path[0]) {
+ sin.sin_family = AF_INET;
+ sin.sin_addr.s_addr = INADDR_LOOPBACK;
+ sin.sin_port = 0;
+ encode_inet_addr(sun, &sin, WANT_FRESH);
+ if (real_bind(sk, SA(sun), SUN_LEN(sun)))
+ return (-1);
+ }
+ encode_inet_addr(sun, SIN(*sa), WANT_EXISTING);
+ *sa = SA(sun);
+ *len = SUN_LEN(sun);
+ }
+ }
+ return (0);
+}
+
+static void return_fake_name(struct sockaddr *sa, socklen_t len,
+ struct sockaddr *fake, socklen_t *fakelen)
+{
+ struct sockaddr_in sin;
+ socklen_t alen;
+
+ if (sa->sa_family == AF_UNIX && !decode_inet_addr(&sin, SUN(sa), len)) {
+ sa = SA(&sin);
+ len = sizeof(sin);
+ }
+ alen = len;
+ if (len > *fakelen)
+ len = *fakelen;
+ if (len > 0)
+ memcpy(fake, sa, len);
+ *fakelen = alen;
+}
+
+/* --- Configuration --- */
+
+static char *home(void)
+{
+ char *p;
+ struct passwd *pw;
+
+ if ((p = getenv("HOME")) != 0) return (p);
+ else if ((pw = getpwuid(uid)) != 0) return (pw->pw_dir);
+ else return "/notexist";
+}
+
+static char *tmpdir(void)
+{
+ char *p;
+
+ if ((p = getenv("TMPDIR")) != 0) return (p);
+ else if ((p = getenv("TMP")) != 0) return (p);
+ else return ("/tmp");
+}
+
+static char *user(void)
+{
+ static char buf[16];
+ char *p;
+ struct passwd *pw;
+
+ if ((p = getenv("USER")) != 0) return (p);
+ else if ((p = getenv("LOGNAME")) != 0) return (p);
+ else if ((pw = getpwuid(uid)) != 0) return (pw->pw_name);
+ else {
+ snprintf(buf, sizeof(buf), "uid-%lu", (unsigned long)uid);
+ return (buf);
+ }
+}
+
+#define SKIPSPC do { while (*p && isspace(UC(*p))) p++; } while (0)
+#define NEXTWORD(q) do { \
+ SKIPSPC; \
+ q = p; \
+ while (*p && !isspace(UC(*p))) p++; \
+ if (*p) *p++ = 0; \
+} while (0)
+#define NEXTADDR(q, del) do { \
+ SKIPSPC; \
+ q = p; \
+ while (*p && (*p == '.' || isdigit(UC(*p)))) p++; \
+ del = *p; \
+ if (*p) *p++ = 0; \
+} while (0)
+#define NEXTNUMBER(q, del) do { \
+ SKIPSPC; \
+ q = p; \
+ while (*p && isdigit(UC(*p))) p++; \
+ del = *p; \
+ if (*p) *p++ = 0; \
+} while (0)
+#define RESCAN(del) do { if (del) *--p = del; } while (0)
+#define KWMATCHP(kw) (strncmp(p, kw, sizeof(kw) - 1) == 0 && \
+ !isalnum(UC(p[sizeof(kw) - 1])) && \
+ (p += sizeof(kw) - 1))
+
+static void parse_ports(char **pp, unsigned short *min, unsigned short *max)
+{
+ char *p = *pp, *q;
+ int del;
+
+ SKIPSPC;
+ if (*p != ':') {
+ *min = 0;
+ *max = 0xffff;
+ } else {
+ p++;
+ NEXTNUMBER(q, del);
+ *min = atoi(q);
+ RESCAN(del);
+ SKIPSPC;
+ if (*p == '-') {
+ NEXTNUMBER(q, del);
+ *max = atoi(q);
+ RESCAN(del);
+ } else
+ *max = *min;
+ }
+ *pp = p;
+}
+
+#define ACLNODE(tail_, act_, \
+ minaddr_, maxaddr_, minport_, maxport_) do { \
+ aclnode *a_; \
+ NEW(a_); \
+ a_->act = act_; \
+ a_->minaddr = minaddr_; a_->maxaddr = maxaddr_; \
+ a_->minport = minport_; a_->maxport = maxport_; \
+ *tail_ = a_; tail_ = &a_->next; \
+} while (0)
+
+static void parse_acl_line(char **pp, aclnode ***tail)
+{
+ struct in_addr addr;
+ unsigned long minaddr, maxaddr, mask;
+ unsigned short minport, maxport;
+ int i, n;
+ int act;
+ int del;
+ char *p = *pp;
+ char *q;
+
+ SKIPSPC;
+ if (*p == '+') act = ALLOW;
+ else if (*p == '-') act = DENY;
+ else goto bad;
+
+ p++;
+ SKIPSPC;
+ if (KWMATCHP("any")) {
+ minaddr = 0;
+ maxaddr = 0xffffffff;
+ goto justone;
+ } else if (KWMATCHP("local")) {
+ parse_ports(&p, &minport, &maxport);
+ ACLNODE(*tail, act, 0, 0, minport, maxport);
+ ACLNODE(*tail, act, 0xffffffff, 0xffffffff, minport, maxport);
+ for (i = 0; i < n_local_ipaddrs; i++) {
+ minaddr = ntohl(local_ipaddrs[i].s_addr);
+ ACLNODE(*tail, act, minaddr, minaddr, minport, maxport);
+ }
+ } else {
+ if (*p == ':') {
+ minaddr = 0;
+ maxaddr = 0xffffffff;
+ } else {
+ NEXTADDR(q, del);
+ if (inet_pton(AF_INET, q, &addr) <= 0) goto bad;
+ minaddr = ntohl(addr.s_addr);
+ RESCAN(del);
+ SKIPSPC;
+ if (*p == '-') {
+ p++;
+ NEXTADDR(q, del);
+ if (inet_pton(AF_INET, q, &addr) <= 0) goto bad;
+ RESCAN(del);
+ maxaddr = ntohl(addr.s_addr);
+ } else if (*p == '/') {
+ p++;
+ NEXTADDR(q, del);
+ if (strchr(q, '.')) {
+ if (inet_pton(AF_INET, q, &addr) <= 0) goto bad;
+ mask = ntohl(addr.s_addr);
+ } else {
+ n = atoi(q);
+ mask = (~0ul << (32 - n)) & 0xffffffff;
+ }
+ RESCAN(del);
+ minaddr &= mask;
+ maxaddr = minaddr | (mask ^ 0xffffffff);
+ } else
+ maxaddr = minaddr;
+ }
+ justone:
+ parse_ports(&p, &minport, &maxport);
+ ACLNODE(*tail, act, minaddr, maxaddr, minport, maxport);
+ }
+ return;
+
+bad:
+ D( fprintf(stderr, "noip: bad acl spec (ignored)\n"); )
+ return;
+}
+
+static void readconfig(void)
+{
+ FILE *fp;
+ char buf[1024];
+ size_t n;
+ char *p, *cmd;
+
+ if ((p = getenv("NOIP_CONFIG")) == 0)
+ snprintf(p = buf, sizeof(buf), "%s/.noip", home());
+ D( fprintf(stderr, "noip: config file: %s\n", p); )
+ if ((fp = fopen(p, "r")) == 0)
+ goto done;
+
+ while (fgets(buf, sizeof(buf), fp)) {
+ n = strlen(buf);
+ p = buf;
+
+ SKIPSPC;
+ if (!*p || *p == '#') continue;
+ while (n && isspace(UC(buf[n - 1]))) n--;
+ buf[n] = 0;
+ NEXTWORD(cmd);
+ SKIPSPC;
+
+ if (strcmp(cmd, "socketdir") == 0)
+ sockdir = xstrdup(p);
+ else if (strcmp(cmd, "realbind") == 0)
+ parse_acl_line(&p, &bind_tail);
+ else if (strcmp(cmd, "realconnect") == 0)
+ parse_acl_line(&p, &connect_tail);
+ else if (strcmp(cmd, "debug") == 0)
+ debug = *p ? atoi(p) : 1;
+ else
+ D( fprintf(stderr, "noip: bad config command %s\n", cmd); )
+ }
+ fclose(fp);
+
+done:
+ *bind_tail = 0;
+ *connect_tail = 0;
+ if (!sockdir) {
+ snprintf(buf, sizeof(buf), "%s/noip-%s", tmpdir(), user());
+ sockdir = xstrdup(buf);
+ }
+ D( fprintf(stderr, "noip: sockdir: %s\n", sockdir);
+ fprintf(stderr, "noip: realbind acl:\n");
+ dump_acl(bind_real);
+ fprintf(stderr, "noip: realconnect acl:\n");
+ dump_acl(connect_real); )
+}
+
+/* --- Hooks --- */
+
+int socket(int pf, int ty, int proto)
+{
+ if (pf == PF_INET) {
+ pf = PF_UNIX;
+ proto = 0;
+ }
+ return real_socket(pf, ty, proto);
+}
+
+int socketpair(int pf, int ty, int proto, int *sk)
+{
+ if (pf == PF_INET) {
+ pf = PF_UNIX;
+ proto = 0;
+ }
+ return (real_socketpair(pf, ty, proto, sk));
+}
+
+int bind(int sk, const struct sockaddr *sa, socklen_t len)
+{
+ struct sockaddr_un sun;
+
+ if (sa->sa_family == AF_INET) {
+ PRESERVING_ERRNO({
+ if (acl_allows_p(bind_real, SIN(sa))) {
+ if (fixup_real_ip_socket(sk))
+ return (-1);
+ } else {
+ encode_inet_addr(&sun, SIN(sa), WANT_FRESH);
+ sa = SA(&sun);
+ len = SUN_LEN(&sun);
+ }
+ });
+ }
+ return real_bind(sk, sa, len);
+}
+
+int connect(int sk, const struct sockaddr *sa, socklen_t len)
+{
+ struct sockaddr_un sun;
+
+ if (sa->sa_family == AF_INET) {
+ PRESERVING_ERRNO({
+ do_implicit_bind(sk, &sa, &len, &sun);
+ });
+ }
+ return real_connect(sk, sa, len);
+}
+
+ssize_t sendto(int sk, const void *buf, size_t len, int flags,
+ const struct sockaddr *to, socklen_t tolen)
+{
+ struct sockaddr_un sun;
+
+ if (to && to->sa_family == AF_INET) {
+ PRESERVING_ERRNO({
+ do_implicit_bind(sk, &to, &tolen, &sun);
+ });
+ }
+ return real_sendto(sk, buf, len, flags, to, tolen);
+}
+
+ssize_t recvfrom(int sk, void *buf, size_t len, int flags,
+ struct sockaddr *from, socklen_t *fromlen)
+{
+ char sabuf[1024];
+ socklen_t mylen = sizeof(sabuf);
+ ssize_t n;
+
+ if (!from)
+ return real_recvfrom(sk, buf, len, flags, 0, 0);
+ PRESERVING_ERRNO({
+ n = real_recvfrom(sk, buf, len, flags, SA(sabuf), &mylen);
+ if (n < 0)
+ return (-1);
+ return_fake_name(SA(sabuf), mylen, from, fromlen);
+ });
+ return (n);
+}
+
+ssize_t sendmsg(int sk, const struct msghdr *msg, int flags)
+{
+ struct sockaddr_un sun;
+ const struct sockaddr *sa;
+ struct msghdr mymsg;
+
+ if (msg->msg_name && SA(msg->msg_name)->sa_family == AF_INET) {
+ PRESERVING_ERRNO({
+ sa = SA(msg->msg_name);
+ mymsg = *msg;
+ do_implicit_bind(sk, &sa, &mymsg.msg_namelen, &sun);
+ mymsg.msg_name = SA(sa);
+ msg = &mymsg;
+ });
+ }
+ return real_sendmsg(sk, msg, flags);
+}
+
+ssize_t recvmsg(int sk, struct msghdr *msg, int flags)
+{
+ char sabuf[1024];
+ struct sockaddr *sa;
+ socklen_t len;
+ ssize_t n;
+
+ if (!msg->msg_name)
+ return real_recvmsg(sk, msg, flags);
+ PRESERVING_ERRNO({
+ sa = SA(msg->msg_name);
+ len = msg->msg_namelen;
+ msg->msg_name = sabuf;
+ msg->msg_namelen = sizeof(sabuf);
+ n = real_recvmsg(sk, msg, flags);
+ if (n < 0)
+ return (-1);
+ return_fake_name(SA(sabuf), msg->msg_namelen, sa, &len);
+ msg->msg_name = sa;
+ msg->msg_namelen = len;
+ });
+ return (n);
+}
+
+int accept(int sk, struct sockaddr *sa, socklen_t *len)
+{
+ char sabuf[1024];
+ socklen_t mylen = sizeof(sabuf);
+ int nsk = real_accept(sk, SA(sabuf), &mylen);
+
+ if (nsk < 0)
+ return (-1);
+ return_fake_name(SA(sabuf), mylen, sa, len);
+ return (nsk);
+}
+
+int getsockname(int sk, struct sockaddr *sa, socklen_t *len)
+{
+ PRESERVING_ERRNO({
+ char sabuf[1024];
+ socklen_t mylen = sizeof(sabuf);
+ if (real_getsockname(sk, SA(sabuf), &mylen))
+ return (-1);
+ return_fake_name(SA(sabuf), mylen, sa, len);
+ });
+ return (0);
+}
+
+int getpeername(int sk, struct sockaddr *sa, socklen_t *len)
+{
+ PRESERVING_ERRNO({
+ char sabuf[1024];
+ socklen_t mylen = sizeof(sabuf);
+ if (real_getpeername(sk, SA(sabuf), &mylen))
+ return (-1);
+ return_fake_name(SA(sabuf), mylen, sa, len);
+ });
+ return (0);
+}
+
+int getsockopt(int sk, int lev, int opt, void *p, socklen_t *len)
+{
+ switch (lev) {
+ case SOL_IP:
+ case SOL_TCP:
+ case SOL_UDP:
+ if (*len > 0)
+ memset(p, 0, *len);
+ return (0);
+ }
+ return real_getsockopt(sk, lev, opt, p, len);
+}
+
+int setsockopt(int sk, int lev, int opt, const void *p, socklen_t len)
+{
+ switch (lev) {
+ case SOL_IP:
+ case SOL_TCP:
+ case SOL_UDP:
+ return (0);
+ }
+ switch (opt) {
+ case SO_BINDTODEVICE:
+ case SO_ATTACH_FILTER:
+ case SO_DETACH_FILTER:
+ return (0);
+ }
+ return real_setsockopt(sk, lev, opt, p, len);
+}
+
+/* --- Initialization --- */
+
+static void cleanup_sockdir(void)
+{
+ DIR *dir;
+ struct dirent *d;
+ struct sockaddr_un sun;
+
+ if ((dir = opendir(sockdir)) == 0)
+ return;
+ while ((d = readdir(dir)) != 0) {
+ if (d->d_name[0] == '.') continue;
+ snprintf(sun.sun_path, sizeof(sun.sun_path),
+ "%s/%s", sockdir, d->d_name);
+ if (unix_socket_status(&sun, 0) == STALE) {
+ D( fprintf(stderr, "noip: clearing away stale socket %s\n",
+ d->d_name); )
+ unlink(sun.sun_path);
+ }
+ }
+ closedir(dir);
+}
+
+static void get_local_ipaddrs(void)
+{
+ struct if_nameindex *ifn;
+ struct ifreq ifr;
+ int sk;
+ int i;
+
+ ifn = if_nameindex();
+ if ((sk = real_socket(PF_INET, SOCK_STREAM, 00)) < 0)
+ return;
+ for (i = n_local_ipaddrs = 0;
+ n_local_ipaddrs < MAX_LOCAL_IPADDRS &&
+ ifn[i].if_name && *ifn[i].if_name;
+ i++) {
+ strcpy(ifr.ifr_name, ifn[i].if_name);
+ if (ioctl(sk, SIOCGIFADDR, &ifr) || ifr.ifr_addr.sa_family != AF_INET)
+ continue;
+ local_ipaddrs[n_local_ipaddrs++] =
+ SIN(&ifr.ifr_addr)->sin_addr;
+ D( fprintf(stderr, "noip: local addr %s = %s\n", ifn[i].if_name,
+ inet_ntoa(local_ipaddrs[n_local_ipaddrs - 1])); )
+ }
+ close(sk);
+}
+
+static void setup(void)
+{
+ PRESERVING_ERRNO({
+ char *p;
+
+ import();
+ uid = getuid();
+ if ((p = getenv("NOIP_DEBUG")) && atoi(p))
+ debug = 1;
+ get_local_ipaddrs();
+ readconfig();
+ mkdir(sockdir, 0700);
+ cleanup_sockdir();
+ });
+}
~mdw / preload-hacks / commitdiff