X-Git-Url: https://git.distorted.org.uk/~mdw/become/blobdiff_plain/387501aeccded922e560da75c955f664f2faa6cd..af4f4d6a77aceba8e2d6f58d15e894df320e7c24:/src/become.c diff --git a/src/become.c b/src/become.c index c994974..b4956ff 100644 --- a/src/become.c +++ b/src/become.c @@ -1,10 +1,10 @@ /* -*-c-*- * - * $Id: become.c,v 1.5 1997/09/05 11:45:19 mdw Exp $ + * $Id: become.c,v 1.26 2004/04/08 01:36:20 mdw Exp $ * * Main code for `become' * - * (c) 1997 EBI + * (c) 1998 EBI */ /*----- Licensing notice --------------------------------------------------* @@ -26,33 +26,13 @@ * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ -/*----- Revision history --------------------------------------------------* - * - * $Log: become.c,v $ - * Revision 1.5 1997/09/05 11:45:19 mdw - * Add support for different login styles, and environment variable - * manipulation in a safe and useful way. - * - * Revision 1.4 1997/08/20 16:15:13 mdw - * Overhaul of environment handling. Fix daft bug in path search code. - * - * Revision 1.3 1997/08/07 16:28:59 mdw - * Do something useful when users attempt to become themselves. - * - * Revision 1.2 1997/08/04 10:24:20 mdw - * Sources placed under CVS control. - * - * Revision 1.1 1997/07/21 13:47:54 mdw - * Initial revision - * - */ - /*----- Header files ------------------------------------------------------*/ /* --- ANSI headers --- */ #include #include +#include #include #include #include @@ -70,12 +50,23 @@ #include #include +#include #include #include #include +#include extern char **environ; +/* --- mLib --- */ + +#include +#include +#include +#include +#include +#include + /* --- Local headers --- */ #include "become.h" @@ -83,12 +74,9 @@ extern char **environ; #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 --------------------------------------------------*/ @@ -109,12 +97,26 @@ enum { /* --- Login behaviour types --- */ +#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 --- * + * + * Note that these make a handy bitfield. + */ + +#ifdef HAVE_SETGROUPS + enum { - l_preserve, /* Preserve the environment */ - l_user, /* Update who I am */ - l_login /* Do a full login */ + g_unset = 0, /* Nobody's set a preference */ + g_keep = 1, /* Leave the group memberships */ + g_replace = 2, /* Replace group memberships */ + g_merge = (g_keep | g_replace) /* Merge the group memberships */ }; +#endif + /*----- Static variables --------------------------------------------------*/ static sym_table bc__env; @@ -217,7 +219,7 @@ static sym_env *bc__putenv(const char *var, const char *val, if (val) { e = sym_find(&bc__env, var, -1, sizeof(*e), &f); - if (~e->f & envFlag_preserve || force) { + if (!f || ~e->f & envFlag_preserve || force) { if (f) free(e->val); bc__setenv(e, val); @@ -238,6 +240,50 @@ static sym_env *bc__putenv(const char *var, const char *val, return (e); } +/* --- @bc__addGroups@ --- * + * + * Arguments: @gid_t *g@ = pointer to a group array + * @int *png@ = pointer to number of entries in the array + * @const gid_t *a@ = pointer to groups to add + * @int na@ = number of groups to add + * + * Returns: Zero if it was OK, nonzero if we should stop now. + * + * Use: Adds groups to a groups array. + */ + +static int bc__addGroups(gid_t *g, int *png, const gid_t *a, int na) +{ + int i, j; + int ng = *png; + + for (i = 0; i < na; i++) { + + /* --- Ensure this group isn't already in the list --- */ + + for (j = 0; j < ng; j++) { + if (a[i] == g[j]) + goto next_group; + } + + /* --- See if there's room for more --- */ + + if (ng >= NGROUPS_MAX) { + moan("too many groups (system limit exceeded) -- some have been lost"); + *png = ng; + return (-1); + } + + /* --- Add the group --- */ + + g[ng++] = a[i]; + next_group:; + } + + *png = ng; + return (0); +} + /* --- @bc__banner@ --- * * * Arguments: @FILE *fp@ = stream to write on @@ -267,7 +313,10 @@ static void bc__usage(FILE *fp) "Usage: \n" " $ -c \n" " $ [] [ []...]\n" - " $ -d [-p ] [-f ]\n"); +#ifndef NONETWORK + " $ -d [-p ] [-f ]\n" +#endif + ); } /* --- @bc__help@ --- * @@ -307,13 +356,34 @@ static void bc__help(FILE *fp, int suid) "-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" +" [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" +"-m, --merge-groups Merge the lists of groups\n" +"-r, --replace-groups Replace the list 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, @@ -350,13 +420,22 @@ int main(int argc, char *argv[]) /* --- Become server setup parameters --- */ +#ifndef NONETWORK char *conffile = file_RULES; /* Default config file for daemon */ - int port = -1; /* Default port for daemon */ + int port = 0; /* Default port for daemon */ +#endif /* --- Miscellanous shared variables --- */ unsigned flags = 0; /* Various useful flags */ int style = DEFAULT_LOGIN_STYLE; /* Login style */ + gid_t group = -1; /* Default group to set */ + int gstyle = g_unset; /* No group style set yet */ + +#ifdef HAVE_SETGROUPS + gid_t groups[NGROUPS_MAX]; /* Set of groups */ + int ngroups; /* Number of groups in the set */ +#endif /* --- Default argument list executes a shell command --- */ @@ -369,13 +448,13 @@ int main(int argc, char *argv[]) /* --- 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 */ - }; +#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 --- */ @@ -384,12 +463,23 @@ int main(int argc, char *argv[]) if (getuid() != geteuid()) flags |= f_setuid; + /* --- Make sure standard file descriptors are open --- */ + + { + int fd; + do { + if ((fd = open("/dev/null", O_RDWR)) < 0) + die(1, "couldn't open /dev/null: %s", strerror(errno)); + } while (fd <= STDERR_FILENO); + close(fd); + } + /* --- Read the environment into a hashtable --- */ { char **p; - sym_createTable(&bc__env); + sym_create(&bc__env); for (p = environ; *p; p++) bc__putenv(0, *p, 0, 0); } @@ -413,29 +503,56 @@ int main(int argc, char *argv[]) { "set-user", 0, 0, 's' }, { "login", 0, 0, 'l' }, + /* --- Group style options --- */ + + { "group", OPTF_ARGREQ, 0, 'g' }, +#ifdef HAVE_SETGROUPS + { "keep-groups", 0, 0, 'k' }, + { "merge-groups", 0, 0, 'm' }, + { "replace-groups", 0, 0, 'r' }, +#endif + /* --- Command to run options --- */ - { "command", gFlag_argReq, 0, 'c' }, + { "command", OPTF_ARGREQ, 0, 'c' }, /* --- Server options --- */ +#ifndef NONETWORK { "daemon", 0, 0, 'd' }, - { "port", gFlag_argReq, 0, 'p' }, - { "config-file", gFlag_argReq, 0, 'f' }, + { "nofork", 0, 0, 'n' }, + { "port", OPTF_ARGREQ, 0, 'p' }, + { "config-file", OPTF_ARGREQ, 0, 'f' }, +#endif /* --- Tracing options --- */ -#ifdef TRACING - { "impersonate", gFlag_argReq, 0, 'I' }, - { "trace", gFlag_argOpt, 0, 'T' }, - { "trace-level", gFlag_argOpt, 0, 'L' }, +#ifndef NTRACE + { "impersonate", OPTF_ARGREQ, 0, 'I' }, + { "trace", OPTF_ARGOPT, 0, 'T' }, + { "trace-level", OPTF_ARGOPT, 0, 'L' }, #endif { 0, 0, 0, 0 } }; i = mdwopt(argc, argv, - "-" "huv" "esl" "c:" "dp:f:" T("I:T::L:"), + "-" /* Return non-options as options */ + "huv" /* Asking for help */ + "esl" /* Login style options */ +#ifdef HAVE_SETGROUPS + "g:kmr" /* Group style options */ +#else + "g:" /* Group (without @setgroups@) */ +#endif + "c:" /* Command to run options */ +#ifndef NONETWORK + "dnp:f:" /* Server options */ +#endif +#ifndef NTRACE + "I:T::L::" /* Tracing options */ +#endif + , opts, 0, 0, gFlag_envVar); if (i < 0) goto done_options; @@ -463,12 +580,36 @@ int main(int argc, char *argv[]) style = l_preserve; break; case 's': - style = l_user; + style = l_setuser; break; case 'l': style = l_login; break; + /* --- Group style options --- */ + + case 'g': + if (isdigit((unsigned char)optarg[0])) + group = atoi(optarg); + else { + struct group *gr = getgrnam(optarg); + if (!gr) + die(1, "unknown group `%s'", optarg); + group = gr->gr_gid; + } + flags |= f_havegroup; + break; + + case 'k': + gstyle = g_keep; + break; + case 'm': + gstyle = g_merge; + break; + case 'r': + gstyle = g_replace; + break; + /* --- Command to run options --- */ case 'c': @@ -477,15 +618,27 @@ int main(int argc, char *argv[]) /* --- Server options --- */ +#ifndef NONETWORK case 'p': - port = atoi(optarg); + if (isdigit((unsigned char)optarg[0])) + port = htons(atoi(optarg)); + else { + struct servent *s = getservbyname(optarg, "udp"); + if (!s) + 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 --- * * @@ -493,7 +646,7 @@ int main(int argc, char *argv[]) * allow it if we're running setuid. Disable the actual login anyway. */ -#ifdef TRACING +#ifndef NTRACE case 'I': if (flags & f_setuid) @@ -505,7 +658,7 @@ int main(int argc, char *argv[]) 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; @@ -520,7 +673,7 @@ int main(int argc, char *argv[]) * to! */ -#ifdef TRACING +#ifndef TRACE case 'T': { FILE *fp; @@ -528,16 +681,31 @@ int main(int argc, char *argv[]) if (optarg == 0 || strcmp(optarg, "-") == 0) fp = stdout; else { - if ((flags & f_setuid) && access(optarg, W_OK)) { - die("no write permission for trace file file `%s': %s", - optarg, strerror(errno)); + uid_t eu = geteuid(), ru = getuid(); + +#ifdef HAVE_SETREUID + if (setreuid(eu, ru)) +#else + if (seteuid(ru)) +#endif + { + 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)); } + +#ifdef HAVE_SETREUID + if (setreuid(ru, eu)) +#else + if (seteuid(eu)) +#endif + 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; @@ -545,80 +713,33 @@ int main(int argc, char *argv[]) /* --- 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 vavrious\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 @@ -643,9 +764,10 @@ int main(int argc, char *argv[]) /* --- None of the above --- */ if (optarg[sz] == 0 || (optarg[sz] != '=' && optarg[sz + 1] != 0)) { - if (who == 0) + if (!who) { who = optarg; - else { + break; + } else { optind--; goto done_options; } @@ -685,11 +807,13 @@ done_options: /* --- 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 --- */ @@ -710,7 +834,7 @@ done_options: 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; } @@ -723,7 +847,7 @@ done_options: 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); } @@ -734,8 +858,133 @@ done_options: 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 --- */ + + { +#ifdef HAVE_SETGROUPS + gid_t from_gr[NGROUPS_MAX], to_gr[NGROUPS_MAX]; + int n_fgr, n_tgr; +#endif + + /* --- Set the default login group, if there is one --- */ + + if (~flags & f_havegroup) + group = (style == l_preserve) ? from_pw->pw_gid : to_pw->pw_gid; + +#ifndef HAVE_SETGROUPS + + /* --- Check that it's valid --- */ + + if (group != from_pw->pw_gid && group != to_pw->pw_gid) + die(1, "invalid default group"); + +#else + + /* --- Set the default group style --- */ + + if (gstyle == g_unset) + gstyle = (style == l_login) ? g_replace : g_merge; + + /* --- Read in my current set of groups --- */ + + n_fgr = getgroups(NGROUPS_MAX, from_gr); + + /* --- Now read the groups for the target user --- * + * + * Do this even if I'm using the @g_keep@ style -- I'll use it for + * checking that @group@ is valid. + */ + + { + struct group *gr; + char **p; + + n_tgr = 0; + to_gr[n_tgr++] = to_pw->pw_gid; + + setgrent(); + while ((gr = getgrent()) != 0) { + if (gr->gr_gid == to_gr[0]) + continue; + for (p = gr->gr_mem; *p; p++) { + if (strcmp(to_pw->pw_name, *p) == 0) { + to_gr[n_tgr++] = gr->gr_gid; + if (n_tgr >= NGROUPS_MAX) + goto done_groups; + break; + } + } + } + + done_groups: + endgrent(); + } + + /* --- Check that @group@ is reasonable --- */ + + { + int i; + + if (group == getgid() || group == from_pw->pw_gid) + goto group_ok; + for (i = 0; i < n_fgr; i++) { + if (group == from_gr[i]) + goto group_ok; + } + for (i = 0; i < n_tgr; i++) { + if (group == to_gr[i]) + goto group_ok; + } + die(1, "invalid default group"); + group_ok:; + } + + /* --- Phew. Now comes the hard bit --- */ + + { + gid_t ga[4]; + int i; + + i = 0; + ga[i++] = group; + if (gstyle & g_keep) { + ga[i++] = getgid(); + ga[i++] = from_pw->pw_gid; + } + if (gstyle & g_replace) + ga[i++] = to_pw->pw_gid; + + /* --- Style authorities will become apoplectic if shown this --- * + * + * As far as I can see, it's the neatest way of writing it. + */ + + ngroups = 0; + (void)(bc__addGroups(groups, &ngroups, ga, i) || + ((gstyle & g_keep) && + bc__addGroups(groups, &ngroups, from_gr, n_fgr)) || + ((gstyle & g_replace) && + bc__addGroups(groups, &ngroups, to_gr, n_tgr))); + } + +#endif + + /* --- Trace the results of all this --- */ + + T( trace(TRACE_SETUP, "setup: default group == %i", (int)group); ) + +#ifdef HAVE_SETGROUPS + IF_TRACING(TRACE_SETUP, { + int i; + + for (i = 1; i < ngroups; i++) + trace(TRACE_SETUP, "setup: subsidiary group %i", (int)groups[i]); + }) +#endif } /* --- Shell commands are easy --- */ @@ -752,45 +1001,48 @@ done_options: 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 --- */ - /* --- An su-like login needs slightly less effort --- */ + 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; - case l_user: - shell[0] = to_pw->pw_shell; - shell[1] = 0; - todo = shell; - binary = todo[0]; - break; + /* --- An su-like login needs slightly less effort --- */ - /* --- 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; + 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; + } break; + } } /* --- Mangle the environment --- * @@ -827,17 +1079,17 @@ done_options: */ static char *preserve[] = { - "TERM", "DISPLAY", 0 + "TERM", "DISPLAY", "TZ", 0 }; - + /* --- Variables to be expunged --- * * - * Any environment string which has one of the following as a prefix - * will be expunged from the environment passed to the called process. - * The first line lists variables which have been used to list search - * paths for shared libraries: by manipulating these, an attacker could - * replace a standard library with one of his own. The second line lists - * other well-known dangerous environment variables. + * Any environment string which has one of the following as a prefix will + * be expunged from the environment passed to the called process. The + * first line lists variables which have been used to list search paths + * for shared libraries: by manipulating these, an attacker could replace + * a standard library with one of his own. The second line lists other + * well-known dangerous environment variables. */ static char *banned[] = { @@ -854,7 +1106,7 @@ done_options: size_t sz; unsigned f; sym_iter i; - + /* --- Stage one. Preserve display-specific variables --- */ for (pp = preserve; *pp; pp++) { @@ -900,7 +1152,7 @@ done_options: } } /* Fall through */ - case l_user: + case l_setuser: bc__putenv("USER", to_pw->pw_name, envFlag_preserve, 0); bc__putenv("LOGNAME", to_pw->pw_name, envFlag_preserve, 0); bc__putenv("HOME", to_pw->pw_dir, envFlag_preserve, 0); @@ -938,7 +1190,7 @@ done_options: q = e->val + 5; for (p = strtok(p, ":"); p; p = strtok(0, ":")) { - if (p[0] == '.') + if (p[0] != '/') continue; while (*p) *q++ = *p++; @@ -960,7 +1212,7 @@ done_options: 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 --- */ @@ -972,9 +1224,9 @@ done_options: for (pp = banned; *pp; pp++) { if (**pp == '-') { p = *pp + 1; - if (memcmp(e->_base.name, p, strlen(p)) == 0) + if (strncmp(e->_base.name, p, strlen(p)) == 0) goto expunge; - } else if (strcmp(e->_base.name, p) == 0) + } else if (strcmp(e->_base.name, *pp) == 0) goto expunge; } @@ -989,7 +1241,7 @@ done_options: 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; } @@ -1025,17 +1277,29 @@ done_options: 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 */ - (st.st_mode & S_IFMT) == S_IFREG) /* Check it's a file */ + S_ISREG(st.st_mode)) /* Check it's a file */ break; } 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); } @@ -1054,7 +1318,7 @@ done_options: 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++ = '/'; } @@ -1070,7 +1334,7 @@ done_options: */ 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 --- */ @@ -1121,17 +1385,20 @@ done_options: * * If the user is already what she wants to be, then print a warning. * Then, if I was just going to spawn a shell, quit, to reduce user - * confusion. Otherwise, do what was wanted anyway. + * confusion. Otherwise, do what was wanted anyway. Also, don't bother + * checking if we're already root -- root can do anything anyway, and at + * least this way we get some logging done, and offer a more friendly + * front-end. */ 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); } } else { - int a = check(&rq); + int a = (rq.from == 0) || check(&rq); syslog(LOG_INFO, "permission %s for %s to become %s to run `%s'", @@ -1139,7 +1406,7 @@ done_options: rq.cmd); if (!a) - die("permission denied"); + die(1, "permission denied"); } /* --- Now do the job --- */ @@ -1149,13 +1416,34 @@ done_options: if (flags & f_dummy) { puts("permission granted"); return (0); - } else { - if (setuid(rq.to) == -1) - die("couldn't set uid: %s", strerror(errno)); - execve(rq.cmd, todo, env); - die("couldn't exec `%s': %s", rq.cmd, strerror(errno)); - return (127); } + +#ifdef HAVE_SETGROUPS + if (setgroups(ngroups, groups) < 0) + die(1, "couldn't set groups: %s", strerror(errno)); +#endif + + if (setgid(group) < 0) + die(1, "couldn't set default group: %s", strerror(errno)); + if (setuid(rq.to) < 0) + 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(1, "couldn't exec `%s': %s", rq.cmd, strerror(errno)); + return (127); } /*----- That's all, folks -------------------------------------------------*/