From cffdf6693ffb50d2a1258d955a162bca83038f25 Mon Sep 17 00:00:00 2001 From: Nick Kralevich Date: Mon, 11 Jun 2012 15:50:57 -0700 Subject: [PATCH] FORTIFY_SOURCE: add snprintf, vsnprintf Add _FORTIFY_SOURCE support for snprintf, vsnprintf At this time, we opt out of these protections for clang, as clang does not implement __builtin_va_arg_pack(). http://clang.llvm.org/docs/UsersManual.html#c_unimpl_gcc Change-Id: I73ebe5ec8dad1dca8898a76d6afb693a25f75375 --- libc/Android.mk | 2 ++ libc/include/stdio.h | 28 +++++++++++++++++ libc/stdio/__snprintf_chk.c | 59 +++++++++++++++++++++++++++++++++++ libc/stdio/__vsnprintf_chk.c | 60 ++++++++++++++++++++++++++++++++++++ 4 files changed, 149 insertions(+) create mode 100644 libc/stdio/__snprintf_chk.c create mode 100644 libc/stdio/__vsnprintf_chk.c diff --git a/libc/Android.mk b/libc/Android.mk index f2784fd5a..c50745711 100644 --- a/libc/Android.mk +++ b/libc/Android.mk @@ -140,6 +140,8 @@ libc_common_src_files := \ stdio/vsscanf.c \ stdio/wbuf.c \ stdio/wsetup.c \ + stdio/__snprintf_chk.c \ + stdio/__vsnprintf_chk.c \ stdlib/_rand48.c \ stdlib/assert.c \ stdlib/atexit.c \ diff --git a/libc/include/stdio.h b/libc/include/stdio.h index 8d3d5d71b..cc3270d81 100644 --- a/libc/include/stdio.h +++ b/libc/include/stdio.h @@ -458,4 +458,32 @@ int vfdprintf(int, const char*, __va_list); __END_DECLS #endif /* _GNU_SOURCE */ +#if defined(__BIONIC_FORTIFY_INLINE) + +__BIONIC_FORTIFY_INLINE +__attribute__((__format__ (printf, 3, 0))) +__attribute__((__nonnull__ (3))) +int vsnprintf(char *str, size_t size, const char *format, __va_list ap) +{ + return __builtin___vsnprintf_chk(str, size, 0, __builtin_object_size(str, 0), format, ap); +} + +# if !defined(__clang__) +/* + * Clang doesn't have support for __builtin_va_arg_pack() + * http://clang.llvm.org/docs/UsersManual.html#c_unimpl_gcc + */ + +__BIONIC_FORTIFY_INLINE +__attribute__((__format__ (printf, 3, 4))) +__attribute__((__nonnull__ (3))) +int snprintf(char *str, size_t size, const char *format, ...) +{ + return __builtin___snprintf_chk(str, size, 0, __builtin_object_size(str, 0), format, __builtin_va_arg_pack()); +} + +# endif /* !defined(__clang__) */ + +#endif /* defined(__BIONIC_FORTIFY_INLINE) */ + #endif /* _STDIO_H_ */ diff --git a/libc/stdio/__snprintf_chk.c b/libc/stdio/__snprintf_chk.c new file mode 100644 index 000000000..dbda3db38 --- /dev/null +++ b/libc/stdio/__snprintf_chk.c @@ -0,0 +1,59 @@ +/* + * Copyright (C) 2012 The Android Open Source Project + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * * Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * * 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 COPYRIGHT HOLDERS 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 + * COPYRIGHT OWNER 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. + */ + +#include +#include + +/* + * Runtime implementation of __builtin____snprintf_chk. + * + * See + * http://gcc.gnu.org/onlinedocs/gcc/Object-Size-Checking.html + * http://gcc.gnu.org/ml/gcc-patches/2004-09/msg02055.html + * for details. + * + * This snprintf check is called if _FORTIFY_SOURCE is defined and + * greater than 0. + */ +int __snprintf_chk( + char *dest, + size_t supplied_size, + int flags, + size_t dest_len_from_compiler, + const char *format, ...) +{ + va_list va; + int retval; + + va_start(va, format); + retval = __vsnprintf_chk(dest, supplied_size, flags, + dest_len_from_compiler, format, va); + va_end(va); + + return retval; +} diff --git a/libc/stdio/__vsnprintf_chk.c b/libc/stdio/__vsnprintf_chk.c new file mode 100644 index 000000000..a1a103920 --- /dev/null +++ b/libc/stdio/__vsnprintf_chk.c @@ -0,0 +1,60 @@ +/* + * Copyright (C) 2012 The Android Open Source Project + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * * Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * * 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 COPYRIGHT HOLDERS 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 + * COPYRIGHT OWNER 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. + */ + +#include +#include +#include +#include + +/* + * Runtime implementation of __builtin____vsnprintf_chk. + * + * See + * http://gcc.gnu.org/onlinedocs/gcc/Object-Size-Checking.html + * http://gcc.gnu.org/ml/gcc-patches/2004-09/msg02055.html + * for details. + * + * This vsnprintf check is called if _FORTIFY_SOURCE is defined and + * greater than 0. + */ +int __vsnprintf_chk( + char *dest, + size_t supplied_size, + int flags, + size_t dest_len_from_compiler, + const char *format, + va_list va) +{ + if (supplied_size > dest_len_from_compiler) { + __libc_android_log_print(ANDROID_LOG_FATAL, "libc", + "*** vsnprintf buffer overflow detected ***\n"); + abort(); + } + + return vsnprintf(dest, supplied_size, format, va); +}