From: Nick Clifton Date: Fri, 31 Oct 2014 10:10:37 +0000 (+0000) Subject: In response to a public outcry the strings program now defaults to using the X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=7fac9594c41ab180979bdf5927ff7f7e1d13a9e9;p=binutils-gdb.git In response to a public outcry the strings program now defaults to using the --all option which displays text from anywhere in the input file(s). The default used to be --data, which only displays text from loadable data sections, but this requires the use of the BFD library. Since the BFD library almost certainly still contains buffer overrun and/or memory corruption bugs, and since the strings program is often used to examine malicious code, it was decided that the --data option option represents a possible security risk. * strings.c: Add new command line option --data to only scan the initialized, loadable data secions of binaries. Choose the default behaviour of --all or --data based upon a configure option. * doc/binutils.texi (strings): Update documentation. Include description of why the --data option might be unsafe. * configure.ac: Add new option --disable-default-strings-all which restores the old behaviour of strings using --data by default. If the option is not used make strings use --all by default. * NEWS: Mention the new behaviour of strings. * configure: Regenerate. * config.in: Regenerate. --- diff --git a/binutils/NEWS b/binutils/NEWS index 126219bbcfa..90544946e4f 100644 --- a/binutils/NEWS +++ b/binutils/NEWS @@ -2,6 +2,11 @@ Changes in 2.25: +* Add --data option to strings to only print strings in loadable, initialized + data sections. Change the default behaviour to be --all, but add a new + configure time option of --disable-default-strings-all to restore the old + default behaviour. + * Add --include-all-whitespace to strings. * Add --dump-section option to objcopy. diff --git a/binutils/config.in b/binutils/config.in index d43b748a71e..076f514754d 100644 --- a/binutils/config.in +++ b/binutils/config.in @@ -18,6 +18,9 @@ /* Should ar and ranlib use -D behavior by default? */ #undef DEFAULT_AR_DETERMINISTIC +/* Should strings use -a behavior by default? */ +#undef DEFAULT_STRINGS_ALL + /* Define to 1 if translation of program messages to the user's native language is requested. */ #undef ENABLE_NLS diff --git a/binutils/configure b/binutils/configure index 51260763c96..70387ea249d 100755 --- a/binutils/configure +++ b/binutils/configure @@ -772,6 +772,7 @@ enable_plugins enable_largefile enable_targets enable_deterministic_archives +enable_default_strings_all enable_werror enable_build_warnings enable_nls @@ -1423,6 +1424,8 @@ Optional Features: --enable-targets alternative target configurations --enable-deterministic-archives ar and ranlib default to -D behavior + --disable-default-strings-all + strings defaults to --data behavior --enable-werror treat compile warnings as errors --enable-build-warnings enable build-time compiler warnings --disable-nls do not use Native Language Support @@ -10984,7 +10987,7 @@ else lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2 lt_status=$lt_dlunknown cat > conftest.$ac_ext <<_LT_EOF -#line 10987 "configure" +#line 10990 "configure" #include "confdefs.h" #if HAVE_DLFCN_H @@ -11090,7 +11093,7 @@ else lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2 lt_status=$lt_dlunknown cat > conftest.$ac_ext <<_LT_EOF -#line 11093 "configure" +#line 11096 "configure" #include "confdefs.h" #if HAVE_DLFCN_H @@ -11681,6 +11684,25 @@ cat >>confdefs.h <<_ACEOF _ACEOF +# Check whether --enable-default-strings-all was given. +if test "${enable_default_strings_all+set}" = set; then : + enableval=$enable_default_strings_all; +if test "${enableval}" = no; then + default_strings_all=0 +else + default_strings_all=1 +fi +else + default_strings_all=1 +fi + + + +cat >>confdefs.h <<_ACEOF +#define DEFAULT_STRINGS_ALL $default_strings_all +_ACEOF + + # Set the 'development' global. . $srcdir/../bfd/development.sh diff --git a/binutils/configure.ac b/binutils/configure.ac index c5da20d62f4..c5aadd8d961 100644 --- a/binutils/configure.ac +++ b/binutils/configure.ac @@ -55,6 +55,18 @@ fi], [default_ar_deterministic=0]) AC_DEFINE_UNQUOTED(DEFAULT_AR_DETERMINISTIC, $default_ar_deterministic, [Should ar and ranlib use -D behavior by default?]) +AC_ARG_ENABLE(default-strings-all, +[AS_HELP_STRING([--disable-default-strings-all], + [strings defaults to --data behavior])], [ +if test "${enableval}" = no; then + default_strings_all=0 +else + default_strings_all=1 +fi], [default_strings_all=1]) + +AC_DEFINE_UNQUOTED(DEFAULT_STRINGS_ALL, $default_strings_all, + [Should strings use -a behavior by default?]) + AM_BINUTILS_WARNINGS AC_CONFIG_HEADERS(config.h:config.in) diff --git a/binutils/doc/binutils.texi b/binutils/doc/binutils.texi index 3874f25a3b6..eee77b1e796 100644 --- a/binutils/doc/binutils.texi +++ b/binutils/doc/binutils.texi @@ -2672,15 +2672,24 @@ strings [@option{-afovV}] [@option{-}@var{min-len}] @c man begin DESCRIPTION strings -For each @var{file} given, @sc{gnu} @command{strings} prints the printable -character sequences that are at least 4 characters long (or the number -given with the options below) and are followed by an unprintable -character. By default, it only prints the strings from the initialized -and loaded sections of object files; for other types of files, it prints -the strings from the whole file. +For each @var{file} given, @sc{gnu} @command{strings} prints the +printable character sequences that are at least 4 characters long (or +the number given with the options below) and are followed by an +unprintable character. -@command{strings} is mainly useful for determining the contents of non-text -files. +Depending upon how the strings program was configured it will default +to either displaying all the printable sequences that it can find in +each file, or only those sequences that are in loadable, initialized +data sections. If the file type in unrecognizable, or if strings is +reading from stdin then it will always display all of the printable +sequences that it can find. + +For backwards compatibility any file that occurs after a command line +option of just @option{-} will also be scanned in full, regardless of +the presence of any @option{-d} option. + +@command{strings} is mainly useful for determining the contents of +non-text files. @c man end @@ -2690,8 +2699,25 @@ files. @item -a @itemx --all @itemx - -Do not scan only the initialized and loaded sections of object files; -scan the whole files. +Scan the whole file, regardless of what sections it contains or +whether those sections are loaded or initialized. Normally this is +the default behaviour, but strings can be configured so that the +@option{-d} is the default instead. + +The @option{-} option is position dependent and forces strings to +perform full scans of any file that is mentioned after the @option{-} +on the command line, even if the @option{-d} option has been +specified. + +@item -d +@itemx --data +Only print strings from initialized, loaded data sections in the +file. This may reduce the amount of garbage in the output, but it +also exposes the strings program to any security flaws that may be +present in the BFD library used to scan and load sections. Strings +can be configured so that this option is the default behaviour. In +such cases the @option{-a} option can be used to avoid using the BFD +library and instead just print all of the strings found in the file. @item -f @itemx --print-file-name diff --git a/binutils/strings.c b/binutils/strings.c index f92132b6230..2cf046fded1 100644 --- a/binutils/strings.c +++ b/binutils/strings.c @@ -21,7 +21,10 @@ Options: --all -a - - Do not scan only the initialized data section of object files. + - Scan each file in its entirety. + + --data + -d Scan only the initialized data section(s) of object files. --print-file-name -f Print the name of the file before each string. @@ -114,6 +117,7 @@ static int encoding_bytes; static struct option long_options[] = { {"all", no_argument, NULL, 'a'}, + {"data", no_argument, NULL, 'd'}, {"print-file-name", no_argument, NULL, 'f'}, {"bytes", required_argument, NULL, 'n'}, {"radix", required_argument, NULL, 't'}, @@ -136,7 +140,7 @@ typedef struct static void strings_a_section (bfd *, asection *, void *); static bfd_boolean strings_object_file (const char *); -static bfd_boolean strings_file (char *file); +static bfd_boolean strings_file (char *); static void print_strings (const char *, FILE *, file_ptr, int, int, char *); static void usage (FILE *, int); static long get_char (FILE *, file_ptr *, int *, char **); @@ -167,11 +171,14 @@ main (int argc, char **argv) include_all_whitespace = FALSE; print_addresses = FALSE; print_filenames = FALSE; - datasection_only = TRUE; + if (DEFAULT_STRINGS_ALL) + datasection_only = FALSE; + else + datasection_only = TRUE; target = NULL; encoding = 's'; - while ((optc = getopt_long (argc, argv, "afhHn:wot:e:T:Vv0123456789", + while ((optc = getopt_long (argc, argv, "adfhHn:wot:e:T:Vv0123456789", long_options, (int *) 0)) != EOF) { switch (optc) @@ -180,6 +187,10 @@ main (int argc, char **argv) datasection_only = FALSE; break; + case 'd': + datasection_only = TRUE; + break; + case 'f': print_filenames = TRUE; break; @@ -648,8 +659,18 @@ usage (FILE *stream, int status) { fprintf (stream, _("Usage: %s [option(s)] [file(s)]\n"), program_name); fprintf (stream, _(" Display printable strings in [file(s)] (stdin by default)\n")); - fprintf (stream, _(" The options are:\n\ + fprintf (stream, _(" The options are:\n")); + + if (DEFAULT_STRINGS_ALL) + fprintf (stream, _("\ + -a - --all Scan the entire file, not just the data section [default]\n\ + -d --data Only scan the data sections in the file\n")); + else + fprintf (stream, _("\ -a - --all Scan the entire file, not just the data section\n\ + -d --data Only scan the data sections in the file [default]\n")); + + fprintf (stream, _("\ -f --print-file-name Print the name of the file before each string\n\ -n --bytes=[number] Locate & print any NUL-terminated sequence of at\n\ - least [number] characters (default 4).\n\