diff --git include/unistd.h include/unistd.h index 4c76631..8419b98 100644 --- include/unistd.h +++ include/unistd.h @@ -494,6 +494,7 @@ int initgroups(const char *, gid_t); int iruserok(unsigned long, int, const char *, const char *); int iruserok_sa(const void *, int, int, const char *, const char *); int issetugid(void); +void __FreeBSD_libc_enter_restricted_mode(void); char *mkdtemp(char *); #ifndef _MKNOD_DECLARED int mknod(const char *, mode_t, dev_t); diff --git lib/libc/Versions.def lib/libc/Versions.def index 944cdf6..311f2c7 100644 --- lib/libc/Versions.def +++ lib/libc/Versions.def @@ -20,9 +20,13 @@ FBSD_1.1 { FBSD_1.2 { } FBSD_1.1; +# This version was first added to 10.0-current. +FBSD_1.3 { +} FBSD_1.2; + # This is our private namespace. Any global interfaces that are # strictly for use only by other FreeBSD applications and libraries # are listed here. We use a separate namespace so we can write # simple ABI-checking tools. FBSDprivate_1.0 { -} FBSD_1.2; +} FBSD_1.3; diff --git lib/libc/gen/Makefile.inc lib/libc/gen/Makefile.inc index eacbe0b..f7b2688 100644 --- lib/libc/gen/Makefile.inc +++ lib/libc/gen/Makefile.inc @@ -20,6 +20,7 @@ SRCS+= __getosreldate.c __xuname.c \ getpeereid.c getprogname.c getpwent.c getttyent.c \ getusershell.c getvfsbyname.c glob.c \ initgroups.c isatty.c isinf.c isnan.c jrand48.c lcong48.c \ + libc_dlopen.c \ lockf.c lrand48.c mrand48.c nftw.c nice.c \ nlist.c nrand48.c opendir.c \ pause.c pmadvise.c popen.c posixshm.c pselect.c \ diff --git lib/libc/gen/Symbol.map lib/libc/gen/Symbol.map index 47d50bb..d579a2d 100644 --- lib/libc/gen/Symbol.map +++ lib/libc/gen/Symbol.map @@ -345,6 +345,10 @@ FBSD_1.2 { getpagesizes; }; +FBSD_1.3 { + __FreeBSD_libc_enter_restricted_mode; +}; + FBSDprivate_1.0 { /* needed by thread libraries */ __thr_jtable; diff --git lib/libc/gen/libc_dlopen.c lib/libc/gen/libc_dlopen.c new file mode 100644 index 0000000..2b1aa9e --- /dev/null +++ lib/libc/gen/libc_dlopen.c @@ -0,0 +1,61 @@ +/*- + * Copyright (c) 2011 Xin Li + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * + * $FreeBSD$ + */ + +#include +__FBSDID("$FreeBSD$"); + +#include +#include +#include + +#include "libc_private.h" + +/* + * Whether we want to restrict dlopen()s. + */ +static int __libc_restricted_mode = 0; + +void * +libc_dlopen(const char *path, int mode) +{ + + if (__libc_restricted_mode) { + _rtld_error("Service unavailable -- libc in restricted mode"); + return (NULL); + } else + return (dlopen(path, mode)); +} + +void +__FreeBSD_libc_enter_restricted_mode(void) +{ + + __libc_restricted_mode = 1; + return; +} + diff --git lib/libc/include/libc_private.h lib/libc/include/libc_private.h index 0433789..1d78043 100644 --- lib/libc/include/libc_private.h +++ lib/libc/include/libc_private.h @@ -44,6 +44,17 @@ extern int __isthreaded; /* + * libc should use libc_dlopen internally, which respects a global + * flag where loading of new shared objects can be restricted. + */ +void *libc_dlopen(const char *, int); + +/* + * For dynamic linker. + */ +void _rtld_error(const char *fmt, ...); + +/* * File lock contention is difficult to diagnose without knowing * where locks were set. Allow a debug library to be built which * records the source file and line number of each lock call. diff --git lib/libc/net/nsdispatch.c lib/libc/net/nsdispatch.c index ff9751c..f66d135 100644 --- lib/libc/net/nsdispatch.c +++ lib/libc/net/nsdispatch.c @@ -369,7 +369,7 @@ nss_configure(void) confmod = statbuf.st_mtime; #ifdef NS_CACHING - handle = dlopen(NULL, RTLD_LAZY | RTLD_GLOBAL); + handle = libc_dlopen(NULL, RTLD_LAZY | RTLD_GLOBAL); if (handle != NULL) { nss_cache_cycle_prevention_func = dlsym(handle, "_nss_cache_cycle_prevention_function"); @@ -482,7 +482,7 @@ nss_load_module(const char *source, nss_module_register_fn reg_fn) if (snprintf(buf, sizeof(buf), "nss_%s.so.%d", mod.name, NSS_MODULE_INTERFACE_VERSION) >= (int)sizeof(buf)) goto fin; - mod.handle = dlopen(buf, RTLD_LOCAL|RTLD_LAZY); + mod.handle = libc_dlopen(buf, RTLD_LOCAL|RTLD_LAZY); if (mod.handle == NULL) { #ifdef _NSS_DEBUG /* This gets pretty annoying since the built-in diff --git libexec/ftpd/ftpd.c libexec/ftpd/ftpd.c index 59dc71c..0f2a08c 100644 --- libexec/ftpd/ftpd.c +++ libexec/ftpd/ftpd.c @@ -1546,6 +1546,7 @@ skip: reply(550, "Can't change root."); goto bad; } + __FreeBSD_libc_enter_restricted_mode(); } else /* real user w/o chroot */ homedir = pw->pw_dir; /* diff --git libexec/ftpd/popen.c libexec/ftpd/popen.c index 8a739dc..9f80507 100644 --- libexec/ftpd/popen.c +++ libexec/ftpd/popen.c @@ -143,6 +143,9 @@ ftpd_popen(char *program, char *type) } (void)close(pdes[1]); } + /* Drop privileges before proceeding */ + if (getuid() != geteuid() && setuid(geteuid()) < 0) + _exit(1); if (strcmp(gargv[0], _PATH_LS) == 0) { /* Reset getopt for ls_main() */ optreset = optind = optopt = 1;