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diff --git a/config.h.in b/config.h.in
index 106af3a..30c3928 100644
--- a/config.h.in
+++ b/config.h.in
@@ -87,6 +87,10 @@
don't. */
#undef HAVE_DECL_H_ERRNO
+/* Define to 1 if you have the declaration of `SECCOMP_SET_MODE_FILTER', and
+ to 0 if you don't. */
+#undef HAVE_DECL_SECCOMP_SET_MODE_FILTER
+
/* Define to 1 if you have the declaration of `sys_sigabbrev', and to 0 if you
don't. */
#undef HAVE_DECL_SYS_SIGABBREV
@@ -134,9 +138,21 @@
/* Define to 1 if the compiler supports the __visibility__ attribute. */
#undef HAVE_DSO_VISIBILITY
+/* Define to 1 if you have the `exect' function. */
+#undef HAVE_EXECT
+
+/* Define to 1 if you have the `execvp' function. */
+#undef HAVE_EXECVP
+
+/* Define to 1 if you have the `execvpe' function. */
+#undef HAVE_EXECVPE
+
/* Define to 1 if your system has the F_CLOSEM fcntl. */
#undef HAVE_FCNTL_CLOSEM
+/* Define to 1 if you have the `fexecve' function. */
+#undef HAVE_FEXECVE
+
/* Define to 1 if you have the `fgetln' function. */
#undef HAVE_FGETLN
@@ -421,6 +437,12 @@
/* Define to 1 if you have the `posix_openpt' function. */
#undef HAVE_POSIX_OPENPT
+/* Define to 1 if you have the `posix_spawn' function. */
+#undef HAVE_POSIX_SPAWN
+
+/* Define to 1 if you have the `posix_spawnp' function. */
+#undef HAVE_POSIX_SPAWNP
+
/* Define to 1 if you have the `priv_set' function. */
#undef HAVE_PRIV_SET
@@ -703,6 +725,12 @@
/* Define to 1 if you have the `vsnprintf' function. */
#undef HAVE_VSNPRINTF
+/* Define to 1 if you have the `wordexp' function. */
+#undef HAVE_WORDEXP
+
+/* Define to 1 if you have the <wordexp.h> header file. */
+#undef HAVE_WORDEXP_H
+
/* Define to 1 if you have the <zlib.h> header file. */
#undef HAVE_ZLIB_H
diff --git a/configure.in b/configure.in
index 06b4722..945284e 100644
--- a/configure.in
+++ b/configure.in
@@ -1824,6 +1824,14 @@ case "$host" in
shadow_funcs="getspnam"
shadow_libs_optional="-lshadow"
test -z "$with_pam" && AUTH_EXCL_DEF="PAM"
+ # Check for SECCOMP_SET_MODE_FILTER in linux/seccomp.h
+ AC_CHECK_DECLS([SECCOMP_SET_MODE_FILTER], [], [], [
+#include <sys/types.h>
+#include <sys/prctl.h>
+#include <asm/unistd.h>
+#include <linux/seccomp.h>
+#include <linux/filter.h>
+ ])
;;
*-convex-bsd*)
OSDEFS="${OSDEFS} -D_CONVEX_SOURCE"
@@ -2091,7 +2099,7 @@ AC_HEADER_DIRENT
AC_HEADER_TIME
AC_HEADER_STDBOOL
AC_HEADER_MAJOR
-AC_CHECK_HEADERS(malloc.h netgroup.h paths.h spawn.h utime.h utmpx.h sys/sockio.h sys/bsdtypes.h sys/select.h sys/stropts.h sys/sysmacros.h)
+AC_CHECK_HEADERS(malloc.h netgroup.h paths.h spawn.h utime.h utmpx.h wordexp.h sys/sockio.h sys/bsdtypes.h sys/select.h sys/stropts.h sys/sysmacros.h)
AC_CHECK_HEADERS([procfs.h] [sys/procfs.h], [AC_CHECK_MEMBERS(struct psinfo.pr_ttydev, [AC_CHECK_FUNCS(_ttyname_dev)], [], [AC_INCLUDES_DEFAULT
#ifdef HAVE_PROCFS_H
#include <procfs.h>
@@ -2226,7 +2234,8 @@ dnl
AC_FUNC_GETGROUPS
AC_CHECK_FUNCS(glob strrchr sysconf tzset strftime setenv \
regcomp setlocale nl_langinfo mbr_check_membership \
- setrlimit64)
+ setrlimit64 \
+ wordexp exect execvp execvpe fexecve posix_spawn posix_spawnp)
AC_REPLACE_FUNCS(getgrouplist)
AC_CHECK_FUNCS(getline, [], [
AC_LIBOBJ(getline)
diff --git a/include/missing.h b/include/missing.h
index fda151b..cac8088 100644
--- a/include/missing.h
+++ b/include/missing.h
@@ -198,6 +198,13 @@ typedef struct sigaction sigaction_t;
#endif
/*
+ * The nitems macro may be defined in sys/param.h
+ */
+#ifndef nitems
+# define nitems(_a) (sizeof((_a)) / sizeof((_a)[0]))
+#endif
+
+/*
* If dirfd() does not exists, hopefully dd_fd does.
*/
#if !defined(HAVE_DIRFD) && defined(HAVE_DD_FD)
diff --git a/src/Makefile.in b/src/Makefile.in
index 918cf04..079aa3e 100644
--- a/src/Makefile.in
+++ b/src/Makefile.in
@@ -109,7 +109,7 @@ sudo: $(OBJS) $(LT_LIBS)
$(LIBTOOL) --mode=link $(CC) -o $@ $(OBJS) $(LDFLAGS) $(PIE_LDFLAGS) $(SSP_LDFLAGS) $(LIBS)
libsudo_noexec.la: sudo_noexec.lo
- $(LIBTOOL) --mode=link $(CC) $(LDFLAGS) $(LT_LDFLAGS) -o $@ sudo_noexec.lo -avoid-version -rpath $(noexecdir)
+ $(LIBTOOL) --mode=link $(CC) $(LDFLAGS) $(LT_LDFLAGS) @LIBDL@ -o $@ sudo_noexec.lo -avoid-version -rpath $(noexecdir)
sesh: sesh.o error.o exec_common.o @LIBINTL@ $(LT_LIBS)
$(LIBTOOL) --mode=link $(CC) -o $@ sesh.o error.o exec_common.o $(LDFLAGS) $(PIE_LDFLAGS) $(SSP_LDFLAGS) @LIBINTL@ $(LIBS)
diff --git a/src/sudo_noexec.c b/src/sudo_noexec.c
index 2872501..f04b277 100644
--- a/src/sudo_noexec.c
+++ b/src/sudo_noexec.c
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2004-2005, 2010-2011 Todd C. Miller <Todd.Miller@courtesan.com>
+ * Copyright (c) 2004-2005, 2010-2016 Todd C. Miller <Todd.Miller@courtesan.com>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
@@ -18,20 +18,64 @@
#include <sys/types.h>
+#if defined(HAVE_DECL_SECCOMP_SET_MODE_FILTER) && HAVE_DECL_SECCOMP_SET_MODE_FILTER
+# include <sys/prctl.h>
+# include <asm/unistd.h>
+# include <linux/filter.h>
+# include <linux/seccomp.h>
+#endif
+
#include <errno.h>
#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
#ifdef HAVE_SPAWN_H
#include <spawn.h>
#endif
+#ifdef HAVE_STRING_H
+# include <string.h>
+#endif /* HAVE_STRING_H */
+#ifdef HAVE_STRINGS_H
+# include <strings.h>
+#endif /* HAVE_STRINGS_H */
+#ifdef HAVE_WORDEXP_H
+#include <wordexp.h>
+#endif
+#if defined(HAVE_SHL_LOAD)
+# include <dl.h>
+#elif defined(HAVE_DLOPEN)
+# include <dlfcn.h>
+#endif
#include "missing.h"
+#include "pathnames.h"
+#ifdef HAVE___INTERPOSE
/*
- * Dummy versions of the execve() family of syscalls. We don't need
- * to stub out all of them, just the ones that correspond to actual
- * system calls (which varies by OS). Note that it is still possible
- * to access the real syscalls via the syscall() interface but very
- * few programs actually do that.
+ * Mac OS X 10.4 and above has support for library symbol interposition.
+ * There is a good explanation of this in the Mac OS X Internals book.
+ */
+typedef struct interpose_s {
+ void *new_func;
+ void *orig_func;
+} interpose_t;
+
+# define FN_NAME(fn) dummy_ ## fn
+# define INTERPOSE(fn) \
+ __attribute__((__used__)) static const interpose_t interpose_ ## fn \
+ __attribute__((__section__("__DATA,__interpose"))) = \
+ { (void *)dummy_ ## fn, (void *)fn };
+#else
+# define FN_NAME(fn) fn
+# define INTERPOSE(fn)
+#endif
+
+/*
+ * Dummy versions of the exec(3) family of syscalls. It is not enough to
+ * just dummy out execve(2) since many C libraries do not call the public
+ * execve(2) interface. Note that it is still possible to access the real
+ * syscalls via the syscall(2) interface, but that is rarely done.
*/
#define DUMMY_BODY \
@@ -40,61 +84,172 @@
return -1; \
}
+#define DUMMY1(fn, t1) \
+__dso_public int \
+FN_NAME(fn)(t1 a1) \
+DUMMY_BODY \
+INTERPOSE(fn)
+
#define DUMMY2(fn, t1, t2) \
__dso_public int \
-fn(t1 a1, t2 a2) \
-DUMMY_BODY
+FN_NAME(fn)(t1 a1, t2 a2) \
+DUMMY_BODY \
+INTERPOSE(fn)
#define DUMMY3(fn, t1, t2, t3) \
__dso_public int \
-fn(t1 a1, t2 a2, t3 a3) \
-DUMMY_BODY
+FN_NAME(fn)(t1 a1, t2 a2, t3 a3) \
+DUMMY_BODY \
+INTERPOSE(fn)
#define DUMMY6(fn, t1, t2, t3, t4, t5, t6) \
__dso_public int \
-fn(t1 a1, t2 a2, t3 a3, t4 a4, t5 a5, t6 a6) \
-DUMMY_BODY
+FN_NAME(fn)(t1 a1, t2 a2, t3 a3, t4 a4, t5 a5, t6 a6) \
+DUMMY_BODY \
+INTERPOSE(fn)
#define DUMMY_VA(fn, t1, t2) \
__dso_public int \
-fn(t1 a1, t2 a2, ...) \
-DUMMY_BODY
+FN_NAME(fn)(t1 a1, t2 a2, ...) \
+DUMMY_BODY \
+INTERPOSE(fn)
+/*
+ * Standard exec(3) family of functions.
+ */
DUMMY_VA(execl, const char *, const char *)
-DUMMY_VA(_execl, const char *, const char *)
-DUMMY_VA(__execl, const char *, const char *)
DUMMY_VA(execle, const char *, const char *)
-DUMMY_VA(_execle, const char *, const char *)
-DUMMY_VA(__execle, const char *, const char *)
DUMMY_VA(execlp, const char *, const char *)
-DUMMY_VA(_execlp, const char *, const char *)
-DUMMY_VA(__execlp, const char *, const char *)
-DUMMY3(exect, const char *, char * const *, char * const *)
-DUMMY3(_exect, const char *, char * const *, char * const *)
-DUMMY3(__exect, const char *, char * const *, char * const *)
DUMMY2(execv, const char *, char * const *)
-DUMMY2(_execv, const char *, char * const *)
-DUMMY2(__execv, const char *, char * const *)
DUMMY2(execvp, const char *, char * const *)
-DUMMY2(_execvp, const char *, char * const *)
-DUMMY2(__execvp, const char *, char * const *)
-DUMMY3(execvP, const char *, const char *, char * const *)
-DUMMY3(_execvP, const char *, const char *, char * const *)
-DUMMY3(__execvP, const char *, const char *, char * const *)
DUMMY3(execve, const char *, char * const *, char * const *)
-DUMMY3(_execve, const char *, char * const *, char * const *)
-DUMMY3(__execve, const char *, char * const *, char * const *)
+
+/*
+ * Non-standard exec(3) functions and corresponding private versions.
+ */
+#ifdef HAVE_EXECVP
+DUMMY3(execvP, const char *, const char *, char * const *)
+#endif
+#ifdef HAVE_EXECVPE
DUMMY3(execvpe, const char *, char * const *, char * const *)
-DUMMY3(_execvpe, const char *, char * const *, char * const *)
-DUMMY3(__execvpe, const char *, char * const *, char * const *)
+#endif
+#ifdef HAVE_EXECT
+DUMMY3(exect, const char *, char * const *, char * const *)
+#endif
+
+/*
+ * Not all systems support fexecve(2), posix_spawn(2) and posix_spawnp(2).
+ */
+#ifdef HAVE_FEXECVE
DUMMY3(fexecve, int , char * const *, char * const *)
-DUMMY3(_fexecve, int , char * const *, char * const *)
-DUMMY3(__fexecve, int , char * const *, char * const *)
-#ifdef HAVE_SPAWN_H
+#endif
+#ifdef HAVE_POSIX_SPAWN
DUMMY6(posix_spawn, pid_t *, const char *, const posix_spawn_file_actions_t *, const posix_spawnattr_t *, char * const *, char * const *)
-DUMMY6(_posix_spawn, pid_t *, const char *, const posix_spawn_file_actions_t *, const posix_spawnattr_t *, char * const *, char * const *)
-DUMMY6(__posix_spawn, pid_t *, const char *, const posix_spawn_file_actions_t *, const posix_spawnattr_t *, char * const *, char * const *)
+#endif
+#ifdef HAVE_POSIX_SPAWNP
DUMMY6(posix_spawnp, pid_t *, const char *, const posix_spawn_file_actions_t *, const posix_spawnattr_t *, char * const *, char * const *)
-DUMMY6(_posix_spawnp, pid_t *, const char *, const posix_spawn_file_actions_t *, const posix_spawnattr_t *, char * const *, char * const *)
-DUMMY6(__posix_spawnp, pid_t *, const char *, const posix_spawn_file_actions_t *, const posix_spawnattr_t *, char * const *, char * const *)
-#endif /* HAVE_SPAWN_H */
+#endif
+
+/*
+ * system(3) and popen(3).
+ * We can't use a wrapper for popen since it returns FILE *, not int.
+ */
+DUMMY1(system, const char *)
+
+__dso_public FILE *
+FN_NAME(popen)(const char *c, const char *t)
+{
+ errno = EACCES;
+ return NULL;
+}
+INTERPOSE(popen)
+
+#if defined(HAVE_WORDEXP) && (defined(RTLD_NEXT) || defined(HAVE_SHL_LOAD) || defined(HAVE___INTERPOSE))
+/*
+ * We can't use a wrapper for wordexp(3) since we still want to call
+ * the real wordexp(3) but with WRDE_NOCMD added to the flags argument.
+ */
+typedef int (*sudo_fn_wordexp_t)(const char *, wordexp_t *, int);
+
+__dso_public int
+FN_NAME(wordexp)(const char *words, wordexp_t *we, int flags)
+{
+#if defined(HAVE___INTERPOSE)
+ return wordexp(words, we, flags | WRDE_NOCMD);
+#else
+# if defined(HAVE_DLOPEN)
+ void *fn = dlsym(RTLD_NEXT, "wordexp");
+# elif defined(HAVE_SHL_LOAD)
+ const char *name, *myname = _PATH_SUDO_NOEXEC;
+ struct shl_descriptor *desc;
+ void *fn = NULL;
+ int idx = 0;
+
+ name = strrchr(myname, '/');
+ if (name != NULL)
+ myname = name + 1;
+
+ /* Search for wordexp() but skip this shared object. */
+ while (shl_get(idx++, &desc) == 0) {
+ name = strrchr(desc->filename, '/');
+ if (name == NULL)
+ name = desc->filename;
+ else
+ name++;
+ if (strcmp(name, myname) == 0)
+ continue;
+ if (shl_findsym(&desc->handle, "wordexp", TYPE_PROCEDURE, &fn) == 0)
+ break;
+ }
+# else
+ void *fn = NULL;
+# endif
+ if (fn == NULL) {
+ errno = EACCES;
+ return -1;
+ }
+ return ((sudo_fn_wordexp_t)fn)(words, we, flags | WRDE_NOCMD);
+#endif /* HAVE___INTERPOSE */
+}
+INTERPOSE(wordexp)
+#endif /* HAVE_WORDEXP && (RTLD_NEXT || HAVE_SHL_LOAD || HAVE___INTERPOSE) */
+
+/*
+ * On Linux we can use a seccomp() filter to disable exec.
+ */
+#if defined(HAVE_DECL_SECCOMP_SET_MODE_FILTER) && HAVE_DECL_SECCOMP_SET_MODE_FILTER
+
+/* Older systems may not support execveat(2). */
+#ifndef __NR_execveat
+# define __NR_execveat -1
+#endif
+
+static void noexec_ctor(void) __attribute__((constructor));
+
+static void
+noexec_ctor(void)
+{
+ struct sock_filter exec_filter[] = {
+ /* Load syscall number into the accumulator */
+ BPF_STMT(BPF_LD | BPF_ABS, offsetof(struct seccomp_data, nr)),
+ /* Jump to deny for execve/execveat */
+ BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, __NR_execve, 2, 0),
+ BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, __NR_execveat, 1, 0),
+ /* Allow non-matching syscalls */
+ BPF_STMT(BPF_RET | BPF_K, SECCOMP_RET_ALLOW),
+ /* Deny execve/execveat syscall */
+ BPF_STMT(BPF_RET | BPF_K, SECCOMP_RET_ERRNO | (EACCES & SECCOMP_RET_DATA))
+ };
+ const struct sock_fprog exec_fprog = {
+ nitems(exec_filter),
+ exec_filter
+ };
+
+ /*
+ * SECCOMP_MODE_FILTER will fail unless the process has
+ * CAP_SYS_ADMIN or the no_new_privs bit is set.
+ */
+ if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) == 0)
+ (void)prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &exec_fprog);
+}
+#endif /* HAVE_DECL_SECCOMP_SET_MODE_FILTER */