X-Git-Url: https://git.armaanb.net/?a=blobdiff_plain;f=doas.c;h=a184650ba38ea9b4f8c781fd791a869efee32dc1;hb=b82ffa68a6436ce3f4c4b480bc9c12ac284b0d99;hp=c658e9cbe6d056221c7c530fb05479b366a08967;hpb=92f869cf0ae0aa1493a6eefaac253bce2afd9178;p=opendoas.git diff --git a/doas.c b/doas.c index c658e9c..a184650 100644 --- a/doas.c +++ b/doas.c @@ -1,4 +1,4 @@ -/* $OpenBSD: doas.c,v 1.1 2015/07/16 20:44:21 tedu Exp $ */ +/* $OpenBSD: doas.c,v 1.52 2016/04/28 04:48:56 tedu Exp $ */ /* * Copyright (c) 2015 Ted Unangst * @@ -14,11 +14,17 @@ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ + +#include "config.h" + #include +#include +#include #include +#ifdef HAVE_LOGIN_CAP_H #include -#include +#endif #include #include #include @@ -27,27 +33,20 @@ #include #include #include +#include +#include +#include "openbsd.h" #include "doas.h" static void __dead usage(void) { - fprintf(stderr, "usage: doas [-u user] command [args]\n"); + fprintf(stderr, "usage: doas [-Lns] [-C config] [-u user]" + " command [args]\n"); exit(1); } -size_t -arraylen(const char **arr) -{ - size_t cnt = 0; - while (*arr) { - cnt++; - arr++; - } - return cnt; -} - static int parseuid(const char *s, uid_t *uid) { @@ -56,9 +55,11 @@ parseuid(const char *s, uid_t *uid) if ((pw = getpwnam(s)) != NULL) { *uid = pw->pw_uid; + if (*uid == UID_MAX) + return -1; return 0; } - *uid = strtonum(s, 0, UID_MAX, &errstr); + *uid = strtonum(s, 0, UID_MAX - 1, &errstr); if (errstr) return -1; return 0; @@ -76,30 +77,33 @@ uidcheck(const char *s, uid_t desired) return 0; } -static gid_t -strtogid(const char *s) +static int +parsegid(const char *s, gid_t *gid) { struct group *gr; const char *errstr; - gid_t gid; - if ((gr = getgrnam(s)) != NULL) - return gr->gr_gid; - gid = strtonum(s, 0, GID_MAX, &errstr); + if ((gr = getgrnam(s)) != NULL) { + *gid = gr->gr_gid; + if (*gid == GID_MAX) + return -1; + return 0; + } + *gid = strtonum(s, 0, GID_MAX - 1, &errstr); if (errstr) return -1; - return gid; + return 0; } static int match(uid_t uid, gid_t *groups, int ngroups, uid_t target, const char *cmd, - struct rule *r) + const char **cmdargs, struct rule *r) { int i; if (r->ident[0] == ':') { - gid_t rgid = strtogid(r->ident + 1); - if (rgid == -1) + gid_t rgid; + if (parsegid(r->ident + 1, &rgid) == -1) return 0; for (i = 0; i < ngroups; i++) { if (rgid == groups[i]) @@ -113,20 +117,34 @@ match(uid_t uid, gid_t *groups, int ngroups, uid_t target, const char *cmd, } if (r->target && uidcheck(r->target, target) != 0) return 0; - if (r->cmd && strcmp(r->cmd, cmd) != 0) - return 0; + if (r->cmd) { + if (strcmp(r->cmd, cmd)) + return 0; + if (r->cmdargs) { + /* if arguments were given, they should match explicitly */ + for (i = 0; r->cmdargs[i]; i++) { + if (!cmdargs[i]) + return 0; + if (strcmp(r->cmdargs[i], cmdargs[i])) + return 0; + } + if (cmdargs[i]) + return 0; + } + } return 1; } static int -permit(uid_t uid, gid_t *groups, int ngroups, struct rule **lastr, - uid_t target, const char *cmd) +permit(uid_t uid, gid_t *groups, int ngroups, const struct rule **lastr, + uid_t target, const char *cmd, const char **cmdargs) { int i; *lastr = NULL; for (i = 0; i < nrules; i++) { - if (match(uid, groups, ngroups, target, cmd, rules[i])) + if (match(uid, groups, ngroups, target, cmd, + cmdargs, rules[i])) *lastr = rules[i]; } if (!*lastr) @@ -135,135 +153,140 @@ permit(uid_t uid, gid_t *groups, int ngroups, struct rule **lastr, } static void -parseconfig(const char *filename) +parseconfig(const char *filename, int checkperms) { extern FILE *yyfp; extern int yyparse(void); + struct stat sb; yyfp = fopen(filename, "r"); - if (!yyfp) { - fprintf(stderr, "doas is not enabled.\n"); - exit(1); + if (!yyfp) + err(1, checkperms ? "doas is not enabled, %s" : + "could not open config file %s", filename); + + if (checkperms) { + if (fstat(fileno(yyfp), &sb) != 0) + err(1, "fstat(\"%s\")", filename); + if ((sb.st_mode & (S_IWGRP|S_IWOTH)) != 0) + errx(1, "%s is writable by group or other", filename); + if (sb.st_uid != 0) + errx(1, "%s is not owned by root", filename); } + yyparse(); fclose(yyfp); + if (parse_errors) + exit(1); } -static int -copyenvhelper(const char **oldenvp, const char **safeset, int nsafe, char **envp, int ei) -{ - int i; - for (i = 0; i < nsafe; i++) { - const char **oe = oldenvp; - while (*oe) { - size_t len = strlen(safeset[i]); - if (strncmp(*oe, safeset[i], len) == 0 && - (*oe)[len] == '=') { - if (!(envp[ei++] = strdup(*oe))) - err(1, "strdup"); - break; - } - oe++; - } - } - return ei; -} - -static char ** -copyenv(const char **oldenvp, struct rule *rule) +static void __dead +checkconfig(const char *confpath, int argc, char **argv, + uid_t uid, gid_t *groups, int ngroups, uid_t target) { - const char *safeset[] = { - "DISPLAY", "HOME", "LOGNAME", "MAIL", "SHELL", - "PATH", "TERM", "USER", "USERNAME", - NULL, - }; - int nsafe; - int nextras = 0; - char **envp; - const char **extra; - int ei; - int i, j; - - if ((rule->options & KEEPENV) && !rule->envlist) { - j = arraylen(oldenvp); - envp = reallocarray(NULL, j + 1, sizeof(char *)); - for (i = 0; i < j; i++) { - if (!(envp[i] = strdup(oldenvp[i]))) - err(1, "strdup"); - } - envp[i] = NULL; - return envp; - } + const struct rule *rule; - nsafe = arraylen(safeset); - if ((extra = rule->envlist)) { - nextras = arraylen(extra); - for (i = 0; i < nsafe; i++) { - for (j = 0; j < nextras; j++) { - if (strcmp(extra[j], safeset[i]) == 0) { - extra[j--] = extra[nextras--]; - extra[nextras] = NULL; - } - } - } - } - - envp = reallocarray(NULL, nsafe + nextras + 1, sizeof(char *)); - if (!envp) - err(1, "can't allocate new environment"); + if (setresuid(uid, uid, uid) != 0) + err(1, "setresuid"); - ei = 0; - ei = copyenvhelper(oldenvp, safeset, nsafe, envp, ei); - ei = copyenvhelper(oldenvp, rule->envlist, nextras, envp, ei); - envp[ei] = NULL; + parseconfig(confpath, 0); + if (!argc) + exit(0); - return envp; + if (permit(uid, groups, ngroups, &rule, target, argv[0], + (const char **)argv + 1)) { + printf("permit%s\n", (rule->options & NOPASS) ? " nopass" : ""); + exit(0); + } else { + printf("deny\n"); + exit(1); + } } -static void __dead -fail(void) +int +mygetpwuid_r(uid_t uid, struct passwd *pwd, struct passwd **result) { - const char *msgs[] = { - "No lollygagging!", - "Better luck next time.", - "PEBKAC detected.", - "That's what happens when you're lazy.", - "It is clear that this has not been thought through.", - "That's the most ridiculous thing I've heard in the last two or three minutes!", - "No sane people allowed here. Go home.", - "I would explain, but I am too drunk.", - "You're not allowed to have an opinion.", - "Complaint forms are handled in another department.", - }; - const char *m; - - m = msgs[arc4random_uniform(sizeof(msgs) / sizeof(msgs[0]))]; - fprintf(stderr, "%s\n", m); - exit(1); + int rv; + char *buf; + static long pwsz = 0; + size_t buflen; + + *result = NULL; + + if (pwsz == 0) + pwsz = sysconf(_SC_GETPW_R_SIZE_MAX); + + buflen = pwsz > 0 ? pwsz : 1024; + + buf = malloc(buflen); + if (buf == NULL) + return errno; + + while ((rv = getpwuid_r(uid, pwd, buf, buflen, result)) == ERANGE) { + size_t newsz; + newsz = buflen * 2; + if (newsz < buflen) + return rv; + buflen = newsz; + buf = realloc(buf, buflen); + if (buf == NULL) + return errno; + } + + return rv; } int -main(int argc, char **argv, char **envp) +main(int argc, char **argv) { - char cmdline[1024]; - char myname[32]; - uid_t uid, target = 0; + const char *safepath = "/bin:/sbin:/usr/bin:/usr/sbin:" + "/usr/local/bin:/usr/local/sbin"; + const char *confpath = NULL; + char *shargv[] = { NULL, NULL }; + char *sh; + const char *p; + const char *cmd; + char cmdline[LINE_MAX]; + struct passwd mypwstore, targpwstore; + struct passwd *mypw, *targpw; + const struct rule *rule; + uid_t uid; + uid_t target = 0; gid_t groups[NGROUPS_MAX + 1]; int ngroups; - struct passwd *pw; - struct rule *rule; - const char *cmd; - int i, ch; - const char *safepath = "/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin"; + int i, ch, rv; + int sflag = 0; + int nflag = 0; + char cwdpath[PATH_MAX]; + const char *cwd; + char **envp; + + setprogname("doas"); - parseconfig("/etc/doas.conf"); + closefrom(STDERR_FILENO + 1); - while ((ch = getopt(argc, argv, "u:")) != -1) { + uid = getuid(); + + while ((ch = getopt(argc, argv, "+C:Lnsu:")) != -1) { switch (ch) { + case 'C': + confpath = optarg; + break; + case 'L': +#if defined(USE_TIMESTAMP) + exit(timestamp_clear() == -1); +#else + exit(0); +#endif case 'u': if (parseuid(optarg, &target) != 0) errx(1, "unknown user"); break; + case 'n': + nflag = 1; + break; + case 's': + sflag = 1; + break; default: usage(); break; @@ -272,49 +295,132 @@ main(int argc, char **argv, char **envp) argv += optind; argc -= optind; - if (!argc) + if (confpath) { + if (sflag) + usage(); + } else if ((!sflag && !argc) || (sflag && argc)) usage(); - cmd = argv[0]; - strlcpy(cmdline, argv[0], sizeof(cmdline)); - for (i = 1; i < argc; i++) { - strlcat(cmdline, " ", sizeof(cmdline)); - strlcat(cmdline, argv[i], sizeof(cmdline)); - } - - uid = getuid(); - pw = getpwuid(uid); - if (!pw) - err(1, "getpwuid failed"); - strlcpy(myname, pw->pw_name, sizeof(myname)); + rv = mygetpwuid_r(uid, &mypwstore, &mypw); + if (rv != 0) + err(1, "getpwuid_r failed"); + if (mypw == NULL) + errx(1, "no passwd entry for self"); ngroups = getgroups(NGROUPS_MAX, groups); if (ngroups == -1) err(1, "can't get groups"); groups[ngroups++] = getgid(); - if (!permit(uid, groups, ngroups, &rule, target, cmd)) { - syslog(LOG_AUTHPRIV | LOG_NOTICE, "failed command for %s: %s", myname, cmdline); - fail(); + if (sflag) { + sh = getenv("SHELL"); + if (sh == NULL || *sh == '\0') { + shargv[0] = mypw->pw_shell; + } else + shargv[0] = sh; + argv = shargv; + argc = 1; } + if (confpath) { + checkconfig(confpath, argc, argv, uid, groups, ngroups, + target); + exit(1); /* fail safe */ + } + + if (geteuid()) + errx(1, "not installed setuid"); + + parseconfig(DOAS_CONF, 1); + + /* cmdline is used only for logging, no need to abort on truncate */ + (void)strlcpy(cmdline, argv[0], sizeof(cmdline)); + for (i = 1; i < argc; i++) { + if (strlcat(cmdline, " ", sizeof(cmdline)) >= sizeof(cmdline)) + break; + if (strlcat(cmdline, argv[i], sizeof(cmdline)) >= sizeof(cmdline)) + break; + } + + cmd = argv[0]; + if (!permit(uid, groups, ngroups, &rule, target, cmd, + (const char **)argv + 1)) { + syslog(LOG_AUTHPRIV | LOG_NOTICE, + "command not permitted for %s: %s", mypw->pw_name, cmdline); + errc(1, EPERM, NULL); + } + +#if defined(USE_SHADOW) if (!(rule->options & NOPASS)) { - if (!auth_userokay(myname, NULL, NULL, NULL)) { - syslog(LOG_AUTHPRIV | LOG_NOTICE, "failed password for %s", myname); - fail(); - } + if (nflag) + errx(1, "Authorization required"); + + shadowauth(mypw->pw_name, rule->options & PERSIST); + } +#elif !defined(USE_PAM) + /* no authentication provider, only allow NOPASS rules */ + (void) nflag; + if (!(rule->options & NOPASS)) + errx(1, "Authorization required"); +#endif + + if ((p = getenv("PATH")) != NULL) + formerpath = strdup(p); + if (formerpath == NULL) + formerpath = ""; + + if (rule->cmd) { + if (setenv("PATH", safepath, 1) == -1) + err(1, "failed to set PATH '%s'", safepath); } - envp = copyenv((const char **)envp, rule); - pw = getpwuid(target); - if (!pw) + rv = mygetpwuid_r(target, &targpwstore, &targpw); + if (rv != 0) + err(1, "getpwuid_r failed"); + if (targpw == NULL) errx(1, "no passwd entry for target"); - if (setusercontext(NULL, pw, target, LOGIN_SETGROUP | + +#if defined(USE_PAM) + pamauth(targpw->pw_name, mypw->pw_name, !nflag, rule->options & NOPASS, + rule->options & PERSIST); +#endif + +#ifdef HAVE_LOGIN_CAP_H + if (setusercontext(NULL, targpw, target, LOGIN_SETGROUP | LOGIN_SETPRIORITY | LOGIN_SETRESOURCES | LOGIN_SETUMASK | LOGIN_SETUSER) != 0) errx(1, "failed to set user context for target"); +#else + if (setresgid(targpw->pw_gid, targpw->pw_gid, targpw->pw_gid) != 0) + err(1, "setresgid"); + if (initgroups(targpw->pw_name, targpw->pw_gid) != 0) + err(1, "initgroups"); + if (setresuid(target, target, target) != 0) + err(1, "setresuid"); +#endif + + if (getcwd(cwdpath, sizeof(cwdpath)) == NULL) + cwd = "(failed)"; + else + cwd = cwdpath; + + if (!(rule->options & NOLOG)) { + syslog(LOG_AUTHPRIV | LOG_INFO, + "%s ran command %s as %s from %s", + mypw->pw_name, cmdline, targpw->pw_name, cwd); + } + + envp = prepenv(rule, mypw, targpw); - syslog(LOG_AUTHPRIV | LOG_INFO, "%s ran command as %s: %s", myname, pw->pw_name, cmdline); - setenv("PATH", safepath, 1); + /* setusercontext set path for the next process, so reset it for us */ + if (rule->cmd) { + if (setenv("PATH", safepath, 1) == -1) + err(1, "failed to set PATH '%s'", safepath); + } else { + if (setenv("PATH", formerpath, 1) == -1) + err(1, "failed to set PATH '%s'", formerpath); + } execvpe(cmd, argv, envp); + if (errno == ENOENT) + errx(1, "%s: command not found", cmd); err(1, "%s", cmd); }