X-Git-Url: http://andersk.mit.edu/gitweb/nss_nonlocal.git/blobdiff_plain/f7293a540408a83631cd04ec767962f60b96610f..8870ee9ca4ea1fbe316f18448d5c73f31ad729c7:/nonlocal-passwd.c diff --git a/nonlocal-passwd.c b/nonlocal-passwd.c index 1517341..e915ea0 100644 --- a/nonlocal-passwd.c +++ b/nonlocal-passwd.c @@ -2,7 +2,8 @@ * nonlocal-passwd.c * passwd database for nss_nonlocal proxy. * - * Copyright © 2007 Anders Kaseorg + * Copyright © 2007 Anders Kaseorg and Tim Abbott + * * * Permission is hereby granted, free of charge, to any person * obtaining a copy of this software and associated documentation @@ -42,7 +43,13 @@ #include "nsswitch-internal.h" #include "nonlocal.h" -#define MAGIC_LOCAL_PW_BUFLEN (sysconf(_SC_GETPW_R_SIZE_MAX) + 7) + +enum nss_status +_nss_nonlocal_getpwuid_r(uid_t uid, struct passwd *pwd, + char *buffer, size_t buflen, int *errnop); +enum nss_status +_nss_nonlocal_getpwnam_r(const char *name, struct passwd *pwd, + char *buffer, size_t buflen, int *errnop); static service_user * @@ -59,29 +66,120 @@ nss_passwd_nonlocal_database(void) enum nss_status check_nonlocal_uid(const char *user, uid_t uid, int *errnop) { - enum nss_status status = NSS_STATUS_SUCCESS; + static const char *fct_name = "getpwuid_r"; + static service_user *startp = NULL; + static void *fct_start = NULL; + enum nss_status status; + service_user *nip; + union { + enum nss_status (*l)(uid_t uid, struct passwd *pwd, + char *buffer, size_t buflen, int *errnop); + void *ptr; + } fct; struct passwd pwbuf; - struct passwd *pwbufp = &pwbuf; - int ret; int old_errno = errno; - int buflen = MAGIC_LOCAL_PW_BUFLEN; + + size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX); char *buf = malloc(buflen); if (buf == NULL) { *errnop = ENOMEM; errno = old_errno; return NSS_STATUS_TRYAGAIN; } - errno = 0; - ret = getpwuid_r(uid, pwbufp, buf, buflen, &pwbufp); - if (ret != 0) { - *errnop = errno; - status = NSS_STATUS_TRYAGAIN; - } else if (pwbufp != NULL) { + + if (fct_start == NULL && + __nss_passwd_lookup(&startp, fct_name, &fct_start) != 0) { + free(buf); + return NSS_STATUS_UNAVAIL; + } + nip = startp; + fct.ptr = fct_start; + do { + morebuf: + if (fct.l == _nss_nonlocal_getpwuid_r) + status = NSS_STATUS_NOTFOUND; + else + status = DL_CALL_FCT(fct.l, (uid, &pwbuf, buf, buflen, errnop)); + if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE) { + free(buf); + buflen *= 2; + buf = malloc(buflen); + if (buf == NULL) { + *errnop = ENOMEM; + errno = old_errno; + return NSS_STATUS_TRYAGAIN; + } + goto morebuf; + } + } while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0); + + if (status == NSS_STATUS_SUCCESS) { syslog(LOG_ERR, "nss_nonlocal: possible spoofing attack: non-local user %s has same UID as local user %s!\n", user, pwbuf.pw_name); status = NSS_STATUS_NOTFOUND; + } else if (status != NSS_STATUS_TRYAGAIN) { + status = NSS_STATUS_SUCCESS; } + + free(buf); + return status; +} + +enum nss_status +check_nonlocal_user(const char *user, int *errnop) +{ + static const char *fct_name = "getpwnam_r"; + static service_user *startp = NULL; + static void *fct_start = NULL; + enum nss_status status; + service_user *nip; + union { + enum nss_status (*l)(const char *name, struct passwd *pwd, + char *buffer, size_t buflen, int *errnop); + void *ptr; + } fct; + struct passwd pwbuf; + int old_errno = errno; + + size_t buflen = sysconf(_SC_GETPW_R_SIZE_MAX); + char *buf = malloc(buflen); + if (buf == NULL) { + *errnop = ENOMEM; + errno = old_errno; + return NSS_STATUS_TRYAGAIN; + } + + if (fct_start == NULL && + __nss_passwd_lookup(&startp, fct_name, &fct_start) != 0) { + free(buf); + return NSS_STATUS_UNAVAIL; + } + nip = startp; + fct.ptr = fct_start; + do { + morebuf: + if (fct.l == _nss_nonlocal_getpwnam_r) + status = NSS_STATUS_NOTFOUND; + else + status = DL_CALL_FCT(fct.l, (user, &pwbuf, buf, buflen, errnop)); + if (status == NSS_STATUS_TRYAGAIN && *errnop == ERANGE) { + free(buf); + buflen *= 2; + buf = malloc(buflen); + if (buf == NULL) { + *errnop = ENOMEM; + errno = old_errno; + return NSS_STATUS_TRYAGAIN; + } + goto morebuf; + } + } while (__nss_next(&nip, fct_name, &fct.ptr, status, 0) == 0); + + if (status == NSS_STATUS_SUCCESS) + status = NSS_STATUS_NOTFOUND; + else if (status != NSS_STATUS_TRYAGAIN) + status = NSS_STATUS_SUCCESS; + free(buf); - errno = old_errno; return status; } @@ -163,6 +261,11 @@ _nss_nonlocal_getpwent_r(struct passwd *pwd, char *buffer, size_t buflen, int *errnop) { enum nss_status status; + + char *nonlocal_ignore = getenv(NONLOCAL_IGNORE_ENV); + if (nonlocal_ignore != NULL && nonlocal_ignore[0] != '\0') + return NSS_STATUS_UNAVAIL; + if (pwent_nip == NULL) { status = _nss_nonlocal_setpwent(0); if (status != NSS_STATUS_SUCCESS) @@ -174,7 +277,7 @@ _nss_nonlocal_getpwent_r(struct passwd *pwd, char *buffer, size_t buflen, else { int nonlocal_errno; do - status = DL_CALL_FCT(pwent_fct.l, (pwd, buffer, buflen, errnop)); + status = DL_CALL_FCT(pwent_fct.l, (pwd, buffer, buflen, errnop)); while (status == NSS_STATUS_SUCCESS && check_nonlocal_uid(pwd->pw_name, pwd->pw_uid, &nonlocal_errno) != NSS_STATUS_SUCCESS); } @@ -205,6 +308,10 @@ _nss_nonlocal_getpwnam_r(const char *name, struct passwd *pwd, } fct; int group_errno; + char *nonlocal_ignore = getenv(NONLOCAL_IGNORE_ENV); + if (nonlocal_ignore != NULL && nonlocal_ignore[0] != '\0') + return NSS_STATUS_UNAVAIL; + nip = nss_passwd_nonlocal_database(); if (nip == NULL) return NSS_STATUS_UNAVAIL; @@ -247,7 +354,8 @@ _nss_nonlocal_getpwuid_r(uid_t uid, struct passwd *pwd, } fct; int group_errno; - if (buflen == MAGIC_LOCAL_PW_BUFLEN) + char *nonlocal_ignore = getenv(NONLOCAL_IGNORE_ENV); + if (nonlocal_ignore != NULL && nonlocal_ignore[0] != '\0') return NSS_STATUS_UNAVAIL; nip = nss_passwd_nonlocal_database();