/* -*-c-*-
*
- * $Id: become.c,v 1.11 1997/09/24 09:48:45 mdw Exp $
+ * $Id: become.c,v 1.23 2003/10/12 10:00:06 mdw Exp $
*
* Main code for `become'
*
- * (c) 1997 EBI
+ * (c) 1998 EBI
*/
/*----- Licensing notice --------------------------------------------------*
/*----- Revision history --------------------------------------------------*
*
* $Log: become.c,v $
- * Revision 1.11 1997/09/24 09:48:45 mdw
+ * Revision 1.23 2003/10/12 10:00:06 mdw
+ * Fix for daemon mode. Oops.
+ *
+ * Revision 1.22 2003/10/12 00:14:55 mdw
+ * Major overhaul. Now uses DSA signatures rather than the bogus symmetric
+ * encrypt-and-hope thing. Integrated with mLib and Catacomb.
+ *
+ * Revision 1.21 1999/07/28 09:31:01 mdw
+ * Empty path components are equivalent to `.'.
+ *
+ * Revision 1.20 1999/05/04 16:17:11 mdw
+ * Change to header file name for parser. See log for `parse.h' for
+ * details.
+ *
+ * Revision 1.19 1998/06/29 13:10:41 mdw
+ * Add some commentary regarding an issue in `sudo' which affects `become';
+ * I'm not fixing it yet because I don't think it's important.
+ *
+ * Fixed the PATH lookup code to use the right binary name: `binary' rather
+ * than `todo[0]'. The two only differ when `style' is `l_login', in which
+ * case `binary' has an initial `/' anyway, and the PATH lookup code is
+ * never invoked. The name is used in a buffer-overflow precheck, though,
+ * and auditing is easier if the naming is consistent.
+ *
+ * Revision 1.18 1998/06/26 10:32:54 mdw
+ * Cosmetic change: use sizeof(destination) in memcpy.
+ *
+ * Revision 1.17 1998/06/18 15:06:59 mdw
+ * Close log before execing program to avoid leaving a socket open.
+ *
+ * Revision 1.16 1998/04/23 13:21:04 mdw
+ * Small tweaks. Support no-network configuration option, and rearrange
+ * the help text a little.
+ *
+ * Revision 1.15 1998/01/13 11:10:44 mdw
+ * Add `TZ' to the list of variables to be preserved.
+ *
+ * Revision 1.14 1998/01/12 16:45:39 mdw
+ * Fix copyright date.
+ *
+ * Revision 1.13 1997/09/26 09:14:57 mdw
+ * Merged blowfish branch into trunk.
+ *
+ * Revision 1.12 1997/09/25 16:04:48 mdw
+ * Change directory after becoming someone else, instead of before. This
+ * avoids problems with root-squashed NFS mounts.
+ *
+ * Revision 1.11.2.1 1997/09/26 09:07:58 mdw
+ * Use the Blowfish encryption algorithm instead of IDEA. This is partly
+ * because I prefer Blowfish (without any particularly strong evidence) but
+ * mainly because IDEA is patented and Blowfish isn't.
+ *
+ * Revision 1.11 1997/09/24 09:48:45 mdw
* Fix (scary) overrun bug in group allocation stuff.
*
* Revision 1.10 1997/09/17 10:14:10 mdw
extern char **environ;
+/* --- mLib --- */
+
+#include <mLib/alloc.h>
+#include <mLib/mdwopt.h>
+#include <mLib/quis.h>
+#include <mLib/report.h>
+#include <mLib/sym.h>
+#include <mLib/trace.h>
+
/* --- Local headers --- */
#include "become.h"
#include "check.h"
#include "daemon.h"
#include "lexer.h"
-#include "mdwopt.h"
#include "name.h"
-#include "parser.h"
+#include "parse.h"
#include "rule.h"
-#include "sym.h"
-#include "utils.h"
#include "userdb.h"
/*----- Type definitions --------------------------------------------------*/
/* --- Login behaviour types --- */
-enum {
- l_preserve, /* Preserve the environment */
- l_setuser, /* Update who I am */
- l_login /* Do a full login */
-};
+#define l_preserve 0 /* Preserve the environment */
+#define l_setuser 1 /* Update who I am */
+#define l_login 2 /* Do a full login */
/* --- Group behaviour types --- *
*
"Usage: \n"
" $ -c <shell-command> <user>\n"
" $ [<env-var>] <user> [<command> [<arguments>]...]\n"
- " $ -d [-p <port>] [-f <config-file>]\n");
+#ifndef NONETWORK
+ " $ -d [-p <port>] [-f <config-file>]\n"
+#endif
+ );
}
/* --- @bc__help@ --- *
"-e, --preserve-environment Try to preserve the current environment\n"
"-s, --su, --set-user Set environment variables to reflect USER\n"
"-l, --login Really log in as USER\n"
-"\n"
+" [Default is "
+#if DEFAULT_LOGIN_STYLE == l_preserve
+ "preserve-environment"
+#elif DEFAULT_LOGIN_STYLE == l_setuser
+ "set-user"
+#elif DEFAULT_LOGIN_STYLE == l_login
+ "login"
+#else
+ "poorly configured"
+#endif
+"]\n\n"
"-g GROUP, --group=GROUP Set primary group-id to be GROUP\n"
#ifdef HAVE_SETGROUPS
"-k, --keep-groups Keep your current set of groups\n"
#endif
"\n"
"-c CMD, --command=CMD Run the (Bourne) shell command CMD\n"
+#ifndef NONETWORK
"\n"
"-d, --daemon Start a daemon\n"
+"-n, --nofork In daemon mode, don't fork into background\n"
"-p PORT, --port=PORT In daemon mode, listen on PORT\n"
-"-f FILE, --config-file=FILE In daemon mode, read config from FILE\n");
-#ifdef TRACING
+"-f FILE, --config-file=FILE In daemon mode, read config from FILE\n"
+#endif
+ );
+#ifndef NTRACE
bc__write(fp, "\n");
if (!suid) {
bc__write(fp,
/* --- Become server setup parameters --- */
+#ifndef NONETWORK
char *conffile = file_RULES; /* Default config file for daemon */
int port = 0; /* Default port for daemon */
+#endif
/* --- Miscellanous shared variables --- */
/* --- Definitions for the various flags --- */
- enum {
- f_daemon = 1, /* Start up in daemon mode */
- f_duff = 2, /* Fault in arguments */
- f_login = 4, /* Execute as a login shell */
- f_dummy = 8, /* Don't actually do anything */
- f_setuid = 16, /* We're running setuid */
- f_havegroup = 32 /* Set a default group */
- };
+#define f_daemon 1u /* Start up in daemon mode */
+#define f_duff 2u /* Fault in arguments */
+#define f_shell 4u /* Run a default shell */
+#define f_dummy 8u /* Don't actually do anything */
+#define f_setuid 16u /* We're running setuid */
+#define f_havegroup 32u /* Set a default group */
+#define f_nofork 64u /* Don't fork into background */
/* --- Set up the program name --- */
{
char **p;
- sym_createTable(&bc__env);
+ sym_create(&bc__env);
for (p = environ; *p; p++)
bc__putenv(0, *p, 0, 0);
}
/* --- Server options --- */
+#ifndef NONETWORK
{ "daemon", 0, 0, 'd' },
+ { "nofork", 0, 0, 'n' },
{ "port", gFlag_argReq, 0, 'p' },
{ "config-file", gFlag_argReq, 0, 'f' },
+#endif
/* --- Tracing options --- */
-#ifdef TRACING
+#ifndef NTRACE
{ "impersonate", gFlag_argReq, 0, 'I' },
{ "trace", gFlag_argOpt, 0, 'T' },
{ "trace-level", gFlag_argOpt, 0, 'L' },
"g:" /* Group (without @setgroups@) */
#endif
"c:" /* Command to run options */
- "dp:f:" /* Server options */
-#ifdef TRACING
+#ifndef NONETWORK
+ "dnp:f:" /* Server options */
+#endif
+#ifndef NTRACE
"I:T::L::" /* Tracing options */
#endif
,
else {
struct group *gr = getgrnam(optarg);
if (!gr)
- die("unknown group `%s'", optarg);
+ die(1, "unknown group `%s'", optarg);
group = gr->gr_gid;
}
flags |= f_havegroup;
/* --- Server options --- */
+#ifndef NONETWORK
case 'p':
if (isdigit((unsigned char)optarg[0]))
port = htons(atoi(optarg));
else {
struct servent *s = getservbyname(optarg, "udp");
if (!s)
- die("unknown service name `%s'", optarg);
+ die(1, "unknown service name `%s'", optarg);
port = s->s_port;
}
break;
case 'd':
flags |= f_daemon;
break;
+ case 'n':
+ flags |= f_nofork;
+ break;
case 'f':
conffile = optarg;
break;
+#endif
/* --- Pretend to be a different user --- *
*
* allow it if we're running setuid. Disable the actual login anyway.
*/
-#ifdef TRACING
+#ifndef NTRACE
case 'I':
if (flags & f_setuid)
else
pw = getpwnam(optarg);
if (!pw)
- die("can't impersonate unknown user `%s'", optarg);
+ die(1, "can't impersonate unknown user `%s'", optarg);
from_pw = userdb_copyUser(pw);
rq.from = from_pw->pw_uid;
flags |= f_dummy;
* to!
*/
-#ifdef TRACING
+#ifndef TRACE
case 'T': {
FILE *fp;
if (seteuid(ru))
#endif
{
- die("couldn't temporarily give up privileges: %s",
+ die(1, "couldn't temporarily give up privileges: %s",
strerror(errno));
}
if ((fp = fopen(optarg, "w")) == 0) {
- die("couldn't open trace file `%s' for writing: %s",
+ die(1, "couldn't open trace file `%s' for writing: %s",
optarg, strerror(errno));
}
#else
if (seteuid(eu))
#endif
- die("couldn't regain privileges: %s", strerror(errno));
+ die(1, "couldn't regain privileges: %s", strerror(errno));
}
- traceon(fp, TRACE_DFL);
+ trace_on(fp, TRACE_DFL);
trace(TRACE_MISC, "become: tracing enabled");
} break;
/* --- Setting trace levels --- */
-#ifdef TRACING
+#ifndef NTRACE
case 'L': {
- int sense = 1;
- unsigned int lvl = 0, l;
- const char *p = optarg;
/* --- Table of tracing facilities --- */
- typedef struct tr {
- char ch;
- unsigned int l;
- const char *help;
- } tr;
-
- static tr lvltbl[] = {
+ static trace_opt lvltbl[] = {
{ 'm', TRACE_MISC, "miscellaneous messages" },
{ 's', TRACE_SETUP, "building the request block" },
- { 'd', TRACE_DAEMON, "server process" },
{ 'r', TRACE_RULE, "ruleset scanning" },
{ 'c', TRACE_CHECK, "request checking" },
+#ifndef NONETWORK
+ { 'd', TRACE_DAEMON, "server process" },
{ 'l', TRACE_CLIENT, "client process" },
{ 'R', TRACE_RAND, "random number generator" },
{ 'C', TRACE_CRYPTO, "cryptographic processing of requests" },
+#endif
{ 'y', TRACE_YACC, "parsing configuration file" },
{ 'D', TRACE_DFL, "default tracing options" },
{ 'A', TRACE_ALL, "all tracing options" },
{ 0, 0, 0 }
};
- tr *tp;
/* --- Output some help if there's no arguemnt --- */
- if (!optarg) {
- bc__banner(stdout);
- bc__write(stdout,
- "\n"
- "Tracing options:\n"
- "\n");
- for (tp = lvltbl; tp->l; tp++) {
- if ((flags & f_setuid) == 0 || tp->l & ~TRACE_PRIV)
- printf("%c -- %s\n", tp->ch, tp->help);
- }
- bc__write(stdout,
-"\n"
-"Also, `+' and `-' options are recognised to turn on and off various\n"
-"tracing options. For example, `A-r' enables everything except ruleset\n"
-"tracing, and `A-D+c' is everything except the defaults, but with request\n"
-"check tracing.\n"
-);
- exit(0);
- }
-
- while (*p) {
- if (*p == '+')
- sense = 1;
- else if (*p == '-')
- sense = 0;
- else {
- for (tp = lvltbl; tp->l && *p != tp->ch; tp++)
- ;
- l = tp->l;
- if (flags & f_setuid)
- l &= ~TRACE_PRIV;
- if (l)
- lvl = sense ? (lvl | l) : (lvl & ~l);
- else
- moan("unknown trace option `%c'", *p);
- }
- p++;
- }
-
- tracesetlvl(lvl);
- yydebug = ((lvl & TRACE_YACC) != 0);
+ trace_level(traceopt(lvltbl, optarg, TRACE_DFL,
+ (flags & f_setuid) ? TRACE_PRIV : 0));
} break;
#endif
/* --- Switch to daemon mode if requested --- */
+#ifndef NONETWORK
if (flags & f_daemon) {
T( trace(TRACE_MISC, "become: daemon mode requested"); )
- daemon_init(conffile, port);
+ daemon_init(conffile, port, (flags & f_nofork) ? df_nofork : 0);
exit(0);
}
+#endif
/* --- Open a syslog --- */
else
pw = getpwnam(who);
if (!pw)
- die("unknown user `%s'", who);
+ die(1, "unknown user `%s'", who);
to_pw = userdb_copyUser(pw);
rq.to = pw->pw_uid;
}
rq.from = getuid();
pw = getpwuid(rq.from);
if (!pw)
- die("who are you? (can't find user %li)", (long)rq.from);
+ die(1, "who are you? (can't find user %li)", (long)rq.from);
from_pw = userdb_copyUser(pw);
}
struct hostent *he;
uname(&u);
if ((he = gethostbyname(u.nodename)) == 0)
- die("who am I? (can't resolve `%s')", u.nodename);
- memcpy(&rq.host, he->h_addr, sizeof(struct in_addr));
+ die(1, "who am I? (can't resolve `%s')", u.nodename);
+ memcpy(&rq.host, he->h_addr, sizeof(rq.host));
}
/* --- Fiddle with group ownerships a bit --- */
/* --- Check that it's valid --- */
if (group != from_pw->pw_gid && group != to_pw->pw_gid)
- die("invalid default group");
+ die(1, "invalid default group");
#else
if (group == to_gr[i])
goto group_ok;
}
- die("invalid default group");
+ die(1, "invalid default group");
group_ok:;
}
ngroups = 0;
(void)(bc__addGroups(groups, &ngroups, ga, i) ||
((gstyle & g_keep) &&
- bc__addGroups(groups, &ngroups, from_gr,n_fgr)) ||
+ bc__addGroups(groups, &ngroups, from_gr, n_fgr)) ||
((gstyle & g_replace) &&
bc__addGroups(groups, &ngroups, to_gr, n_tgr)));
}
binary = todo[0];
}
- else switch (style) {
+ else {
+ flags |= f_shell;
- /* --- An unadorned becoming requires little work --- */
+ switch (style) {
- case l_preserve:
- shell[0] = getenv("SHELL");
- if (!shell[0])
- shell[0] = from_pw->pw_shell;
- shell[1] = 0;
- todo = shell;
- binary = todo[0];
- break;
+ /* --- An unadorned becoming requires little work --- */
+
+ case l_preserve:
+ shell[0] = getenv("SHELL");
+ if (!shell[0])
+ shell[0] = from_pw->pw_shell;
+ shell[1] = 0;
+ todo = shell;
+ binary = todo[0];
+ break;
- /* --- An su-like login needs slightly less effort --- */
+ /* --- An su-like login needs slightly less effort --- */
- case l_setuser:
- shell[0] = to_pw->pw_shell;
- shell[1] = 0;
- todo = shell;
- binary = todo[0];
- break;
+ case l_setuser:
+ shell[0] = to_pw->pw_shell;
+ shell[1] = 0;
+ todo = shell;
+ binary = todo[0];
+ break;
- /* --- A login request needs a little bit of work --- */
-
- case l_login: {
- const char *p = strrchr(to_pw->pw_shell, '/');
-
- if (p)
- p++;
- else
- p = to_pw->pw_shell;
- shell[0] = xmalloc(strlen(p) + 2);
- shell[0][0] = '-';
- strcpy(shell[0] + 1, p);
- shell[1] = 0;
- todo = shell;
- binary = to_pw->pw_shell;
- chdir(to_pw->pw_dir);
- } break;
+ /* --- A login request needs a little bit of work --- */
+
+ case l_login: {
+ const char *p = strrchr(to_pw->pw_shell, '/');
+
+ if (p)
+ p++;
+ else
+ p = to_pw->pw_shell;
+ shell[0] = xmalloc(strlen(p) + 2);
+ shell[0][0] = '-';
+ strcpy(shell[0] + 1, p);
+ shell[1] = 0;
+ todo = shell;
+ binary = to_pw->pw_shell;
+ } break;
+ }
}
/* --- Mangle the environment --- *
*/
static char *preserve[] = {
- "TERM", "DISPLAY", 0
+ "TERM", "DISPLAY", "TZ", 0
};
/* --- Variables to be expunged --- *
sz = 0;
- for (sym_createIter(&i, &bc__env); (e = sym_next(&i)) != 0; ) {
+ for (sym_mkiter(&i, &bc__env); (e = sym_next(&i)) != 0; ) {
/* --- Login style expunges all unpreserved variables --- */
env = qq = xmalloc((sz + 1) * sizeof(*qq));
- for (sym_createIter(&i, &bc__env); (e = sym_next(&i)) != 0; )
+ for (sym_mkiter(&i, &bc__env); (e = sym_next(&i)) != 0; )
*qq++ = e->val;
*qq++ = 0;
}
if (strlen(p) + strlen(binary) + 2 > sizeof(rq.cmd))
continue;
- /* --- Now build the pathname and check it --- */
+ /* --- Now build the pathname and check it --- *
+ *
+ * Issue: user can take advantage of these privileges to decide whether
+ * a program with a given name exists. I'm not sure that's
+ * particularly significant: it only works on regular files with
+ * execute permissions, and if you're relying on the names of these
+ * being secret to keep your security up, then you're doing something
+ * deeply wrong anyway. On the other hand, it's useful to allow people
+ * to be able to execute programs and scripts which they wouldn't
+ * otherwise have access to. [This problem was brought up on
+ * Bugtraq, as a complaint against sudo.]
+ */
- sprintf(rq.cmd, "%s/%s", p, todo[0]);
+ if (!*p) p = ".";
+ sprintf(rq.cmd, "%s/%s", p, binary);
if (stat(rq.cmd, &st) == 0 && /* Check it exists */
st.st_mode & 0111 && /* Check it's executable */
S_ISREG(st.st_mode)) /* Check it's a file */
}
if (!p)
- die("couldn't find `%s' in path", todo[0]);
+ die(1, "couldn't find `%s' in path", todo[0]);
binary = rq.cmd;
free(path);
}
q = binary;
if (*q != '/') {
if (!getcwd(b, sizeof(b)))
- die("couldn't read current directory: %s", strerror(errno));
+ die(1, "couldn't read current directory: %s", strerror(errno));
p += strlen(p);
*p++ = '/';
}
*/
if (p >= b + sizeof(b) - 1)
- die("internal error: buffer overflow while canonifying path");
+ die(1, "internal error: buffer overflow while canonifying path");
/* --- Reduce multiple slashes to just one --- */
if (rq.from == rq.to) {
moan("you already are `%s'!", to_pw->pw_name);
- if (!cmd && todo == shell) {
+ if (flags & f_shell) {
moan("(to prevent confusion, I'm not spawning a shell)");
exit(0);
}
rq.cmd);
if (!a)
- die("permission denied");
+ die(1, "permission denied");
}
/* --- Now do the job --- */
#ifdef HAVE_SETGROUPS
if (setgroups(ngroups, groups) < 0)
- die("couldn't set groups: %s", strerror(errno));
+ die(1, "couldn't set groups: %s", strerror(errno));
#endif
if (setgid(group) < 0)
- die("couldn't set default group: %s", strerror(errno));
+ die(1, "couldn't set default group: %s", strerror(errno));
if (setuid(rq.to) < 0)
- die("couldn't set uid: %s", strerror(errno));
+ die(1, "couldn't set uid: %s", strerror(errno));
+
+ /* --- If this was a login, change current directory --- */
+
+ if ((flags & f_shell) &&
+ style == l_login &&
+ chdir(to_pw->pw_dir) < 0) {
+ moan("couldn't change directory to `%s': %s",
+ to_pw->pw_dir, strerror(errno));
+ }
/* --- Finally, call the program --- */
fflush(0);
+ closelog();
execve(rq.cmd, todo, env);
- die("couldn't exec `%s': %s", rq.cmd, strerror(errno));
+ die(1, "couldn't exec `%s': %s", rq.cmd, strerror(errno));
return (127);
}
~mdw / become / blobdiff