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Fix a vulnerability in the smart_rename function.

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Resolves: #1913744
This commit is contained in:
Nick Clifton 2021-01-29 14:55:39 +00:00
parent da81b23637
commit 1c9437f634
2 changed files with 541 additions and 1 deletions
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533
binutils-CVE-2021-20197.patch Normal file
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@ -0,0 +1,533 @@
diff -rup binutils.orig/bfd/bfd-in2.h binutils-2.35.1/bfd/bfd-in2.h
--- binutils.orig/bfd/bfd-in2.h 2021-01-29 11:14:51.848568548 +0000
+++ binutils-2.35.1/bfd/bfd-in2.h 2021-01-29 11:15:33.431322133 +0000
@@ -583,6 +583,8 @@ bfd *bfd_openr (const char *filename, co
bfd *bfd_fdopenr (const char *filename, const char *target, int fd);
+bfd *bfd_fdopenw (const char *filename, const char *target, int fd);
+
bfd *bfd_openstreamr (const char * filename, const char * target,
void * stream);
diff -rup binutils.orig/bfd/opncls.c binutils-2.35.1/bfd/opncls.c
--- binutils.orig/bfd/opncls.c 2021-01-29 11:14:51.846568560 +0000
+++ binutils-2.35.1/bfd/opncls.c 2021-01-29 11:15:33.431322133 +0000
@@ -395,6 +395,39 @@ bfd_fdopenr (const char *filename, const
/*
FUNCTION
+ bfd_fdopenw
+
+SYNOPSIS
+ bfd *bfd_fdopenw (const char *filename, const char *target, int fd);
+
+DESCRIPTION
+ <<bfd_fdopenw>> is exactly like <<bfd_fdopenr>> with the exception that
+ the resulting BFD is suitable for output.
+*/
+
+bfd *
+bfd_fdopenw (const char *filename, const char *target, int fd)
+{
+ bfd *out = bfd_fdopenr (filename, target, fd);
+
+ if (out != NULL)
+ {
+ if (!bfd_write_p (out))
+ {
+ close (fd);
+ _bfd_delete_bfd (out);
+ out = NULL;
+ bfd_set_error (bfd_error_invalid_operation);
+ }
+ else
+ out->direction = write_direction;
+ }
+
+ return out;
+}
+
+/*
+FUNCTION
bfd_openstreamr
SYNOPSIS
diff -rup binutils.orig/binutils/ar.c binutils-2.35.1/binutils/ar.c
--- binutils.orig/binutils/ar.c 2021-01-29 11:14:51.344571539 +0000
+++ binutils-2.35.1/binutils/ar.c 2021-01-29 11:15:56.174187367 +0000
@@ -25,6 +25,7 @@
#include "sysdep.h"
#include "bfd.h"
+#include "libbfd.h"
#include "libiberty.h"
#include "progress.h"
#include "getopt.h"
@@ -1195,20 +1196,26 @@ write_archive (bfd *iarch)
bfd *obfd;
char *old_name, *new_name;
bfd *contents_head = iarch->archive_next;
+ int ofd = -1;
+ struct stat target_stat;
+ bfd_boolean skip_stat = FALSE;
old_name = (char *) xmalloc (strlen (bfd_get_filename (iarch)) + 1);
strcpy (old_name, bfd_get_filename (iarch));
- new_name = make_tempname (old_name);
+ new_name = make_tempname (old_name, &ofd);
if (new_name == NULL)
bfd_fatal (_("could not create temporary file whilst writing archive"));
output_filename = new_name;
- obfd = bfd_openw (new_name, bfd_get_target (iarch));
+ obfd = bfd_fdopenw (new_name, bfd_get_target (iarch), ofd);
if (obfd == NULL)
- bfd_fatal (old_name);
+ {
+ close (ofd);
+ bfd_fatal (old_name);
+ }
output_bfd = obfd;
@@ -1237,6 +1244,14 @@ write_archive (bfd *iarch)
if (!bfd_set_archive_head (obfd, contents_head))
bfd_fatal (old_name);
+#if !defined (_WIN32) || defined (__CYGWIN32__)
+ ofd = dup (ofd);
+ if (iarch == NULL || iarch->iostream == NULL)
+ skip_stat = TRUE;
+ else if (ofd == -1 || fstat (fileno (iarch->iostream), &target_stat) != 0)
+ bfd_fatal (old_name);
+#endif
+
if (!bfd_close (obfd))
bfd_fatal (old_name);
@@ -1246,7 +1261,7 @@ write_archive (bfd *iarch)
/* We don't care if this fails; we might be creating the archive. */
bfd_close (iarch);
- if (smart_rename (new_name, old_name, 0) != 0)
+ if (smart_rename (new_name, old_name, ofd, skip_stat ? NULL : &target_stat, 0) != 0)
xexit (1);
free (old_name);
free (new_name);
diff -rup binutils.orig/binutils/arsup.c binutils-2.35.1/binutils/arsup.c
--- binutils.orig/binutils/arsup.c 2021-01-29 11:14:51.350571503 +0000
+++ binutils-2.35.1/binutils/arsup.c 2021-01-29 11:15:56.174187367 +0000
@@ -345,13 +345,25 @@ ar_save (void)
else
{
char *ofilename = xstrdup (bfd_get_filename (obfd));
+ bfd_boolean skip_stat = FALSE;
+ struct stat target_stat;
+ int ofd = -1;
if (deterministic > 0)
obfd->flags |= BFD_DETERMINISTIC_OUTPUT;
+#if !defined (_WIN32) || defined (__CYGWIN32__)
+ /* It's OK to fail; at worst it will result in SMART_RENAME using a slow
+ copy fallback to write the output. */
+ ofd = dup (fileno (obfd->iostream));
+ if (lstat (real_name, &target_stat) != 0)
+ skip_stat = TRUE;
+#endif
+
bfd_close (obfd);
- smart_rename (ofilename, real_name, 0);
+ smart_rename (ofilename, real_name, ofd,
+ skip_stat ? NULL : &target_stat, 0);
obfd = 0;
free (ofilename);
}
diff -rup binutils.orig/binutils/bucomm.c binutils-2.35.1/binutils/bucomm.c
--- binutils.orig/binutils/bucomm.c 2021-01-29 11:14:51.422571073 +0000
+++ binutils-2.35.1/binutils/bucomm.c 2021-01-29 11:15:33.431322133 +0000
@@ -532,7 +532,7 @@ template_in_dir (const char *path)
as FILENAME. */
char *
-make_tempname (const char *filename)
+make_tempname (const char *filename, int *ofd)
{
char *tmpname = template_in_dir (filename);
int fd;
@@ -550,7 +550,7 @@ make_tempname (const char *filename)
free (tmpname);
return NULL;
}
- close (fd);
+ *ofd = fd;
return tmpname;
}
diff -rup binutils.orig/binutils/bucomm.h binutils-2.35.1/binutils/bucomm.h
--- binutils.orig/binutils/bucomm.h 2021-01-29 11:14:51.350571503 +0000
+++ binutils-2.35.1/binutils/bucomm.h 2021-01-29 11:15:56.174187367 +0000
@@ -51,7 +51,7 @@ int display_info (void);
void print_arelt_descr (FILE *, bfd *, bfd_boolean, bfd_boolean);
-char *make_tempname (const char *);
+char *make_tempname (const char *, int *);
char *make_tempdir (const char *);
bfd_vma parse_vma (const char *, const char *);
@@ -71,7 +71,8 @@ extern void print_version (const char *)
/* In rename.c. */
extern void set_times (const char *, const struct stat *);
-extern int smart_rename (const char *, const char *, int);
+extern int smart_rename (const char *, const char *, int, struct stat *, int);
+
/* In libiberty. */
void *xmalloc (size_t);
diff -rup binutils.orig/binutils/objcopy.c binutils-2.35.1/binutils/objcopy.c
--- binutils.orig/binutils/objcopy.c 2021-01-29 11:14:51.342571551 +0000
+++ binutils-2.35.1/binutils/objcopy.c 2021-01-29 11:15:56.175187361 +0000
@@ -20,6 +20,7 @@
#include "sysdep.h"
#include "bfd.h"
+#include "libbfd.h"
#include "progress.h"
#include "getopt.h"
#include "libiberty.h"
@@ -3711,9 +3712,9 @@ set_long_section_mode (bfd *output_bfd,
/* The top-level control. */
static void
-copy_file (const char *input_filename, const char *output_filename,
- const char *input_target, const char *output_target,
- const bfd_arch_info_type *input_arch)
+copy_file (const char *input_filename, const char *output_filename, int ofd,
+ struct stat *in_stat, const char *input_target,
+ const char *output_target, const bfd_arch_info_type *input_arch)
{
bfd *ibfd;
char **obj_matching;
@@ -3732,7 +3733,7 @@ copy_file (const char *input_filename, c
/* To allow us to do "strip *" without dying on the first
non-object file, failures are nonfatal. */
ibfd = bfd_openr (input_filename, input_target);
- if (ibfd == NULL)
+ if (ibfd == NULL || fstat (fileno (ibfd->iostream), in_stat) != 0)
{
bfd_nonfatal_message (input_filename, NULL, NULL, NULL);
status = 1;
@@ -3786,9 +3787,14 @@ copy_file (const char *input_filename, c
else
force_output_target = TRUE;
- obfd = bfd_openw (output_filename, output_target);
+ if (ofd >= 0)
+ obfd = bfd_fdopenw (output_filename, output_target, ofd);
+ else
+ obfd = bfd_openw (output_filename, output_target);
+
if (obfd == NULL)
{
+ close (ofd);
bfd_nonfatal_message (output_filename, NULL, NULL, NULL);
status = 1;
return;
@@ -3816,13 +3822,19 @@ copy_file (const char *input_filename, c
if (output_target == NULL)
output_target = bfd_get_target (ibfd);
- obfd = bfd_openw (output_filename, output_target);
+ if (ofd >= 0)
+ obfd = bfd_fdopenw (output_filename, output_target, ofd);
+ else
+ obfd = bfd_openw (output_filename, output_target);
+
if (obfd == NULL)
{
+ close (ofd);
bfd_nonfatal_message (output_filename, NULL, NULL, NULL);
status = 1;
return;
}
+
/* This is a no-op on non-Coff targets. */
set_long_section_mode (obfd, ibfd, long_section_names);
@@ -4786,6 +4798,8 @@ strip_main (int argc, char *argv[])
int hold_status = status;
struct stat statbuf;
char *tmpname;
+ int tmpfd = -1;
+ int copyfd = -1;
if (get_file_size (argv[i]) < 1)
{
@@ -4793,18 +4807,18 @@ strip_main (int argc, char *argv[])
continue;
}
- if (preserve_dates)
- /* No need to check the return value of stat().
- It has already been checked in get_file_size(). */
- stat (argv[i], &statbuf);
-
if (output_file == NULL
|| filename_cmp (argv[i], output_file) == 0)
- tmpname = make_tempname (argv[i]);
+ tmpname = make_tempname (argv[i], &tmpfd);
else
tmpname = output_file;
- if (tmpname == NULL)
+ if (tmpname == NULL
+#if !defined (_WIN32) || defined (__CYGWIN32__)
+ /* Retain a copy of TMPFD since we will need it for SMART_RENAME. */
+ || (tmpfd >= 0 && (copyfd = dup (tmpfd)) == -1)
+#endif
+ )
{
bfd_nonfatal_message (argv[i], NULL, NULL,
_("could not create temporary file to hold stripped copy"));
@@ -4813,7 +4827,8 @@ strip_main (int argc, char *argv[])
}
status = 0;
- copy_file (argv[i], tmpname, input_target, output_target, NULL);
+ copy_file (argv[i], tmpname, tmpfd, &statbuf, input_target,
+ output_target, NULL);
if (status == 0)
{
if (preserve_dates)
@@ -4821,12 +4836,18 @@ strip_main (int argc, char *argv[])
if (output_file != tmpname)
status = (smart_rename (tmpname,
output_file ? output_file : argv[i],
- preserve_dates) != 0);
+ copyfd, &statbuf, preserve_dates) != 0);
if (status == 0)
status = hold_status;
}
else
- unlink_if_ordinary (tmpname);
+ {
+#if !defined (_WIN32) || defined (__CYGWIN32__)
+ if (copyfd >= 0)
+ close (copyfd);
+#endif
+ unlink_if_ordinary (tmpname);
+ }
if (output_file != tmpname)
free (tmpname);
}
@@ -5033,7 +5054,8 @@ copy_main (int argc, char *argv[])
bfd_boolean formats_info = FALSE;
bfd_boolean use_globalize = FALSE;
bfd_boolean use_keep_global = FALSE;
- int c;
+ int c, tmpfd = -1;
+ int copyfd = -1;
struct stat statbuf;
const bfd_arch_info_type *input_arch = NULL;
@@ -5870,34 +5892,43 @@ copy_main (int argc, char *argv[])
convert_efi_target (efi);
}
- if (preserve_dates)
- if (stat (input_filename, & statbuf) < 0)
- fatal (_("warning: could not locate '%s'. System error message: %s"),
- input_filename, strerror (errno));
-
/* If there is no destination file, or the source and destination files
are the same, then create a temp and rename the result into the input. */
if (output_filename == NULL
|| filename_cmp (input_filename, output_filename) == 0)
- tmpname = make_tempname (input_filename);
+ tmpname = make_tempname (input_filename, &tmpfd);
else
tmpname = output_filename;
- if (tmpname == NULL)
- fatal (_("warning: could not create temporary file whilst copying '%s', (error: %s)"),
- input_filename, strerror (errno));
+ if (tmpname == NULL
+#if !defined (_WIN32) || defined (__CYGWIN32__)
+ /* Retain a copy of TMPFD since we will need it for SMART_RENAME. */
+ || (tmpfd >= 0 && (copyfd = dup (tmpfd)) == -1)
+#endif
+ )
+ {
+ fatal (_("warning: could not create temporary file whilst copying '%s', (error: %s)"),
+ input_filename, strerror (errno));
+ }
- copy_file (input_filename, tmpname, input_target, output_target, input_arch);
+ copy_file (input_filename, tmpname, tmpfd, &statbuf, input_target,
+ output_target, input_arch);
if (status == 0)
{
if (preserve_dates)
set_times (tmpname, &statbuf);
if (tmpname != output_filename)
- status = (smart_rename (tmpname, input_filename,
+ status = (smart_rename (tmpname, input_filename, copyfd, &statbuf,
preserve_dates) != 0);
}
else
- unlink_if_ordinary (tmpname);
+ {
+#if !defined (_WIN32) || defined (__CYGWIN32__)
+ if (copyfd >= 0)
+ close (copyfd);
+#endif
+ unlink_if_ordinary (tmpname);
+ }
if (tmpname != output_filename)
free (tmpname);
diff -rup binutils.orig/binutils/rename.c binutils-2.35.1/binutils/rename.c
--- binutils.orig/binutils/rename.c 2021-01-29 11:14:51.422571073 +0000
+++ binutils-2.35.1/binutils/rename.c 2021-01-29 11:15:56.175187361 +0000
@@ -131,17 +131,55 @@ set_times (const char *destination, cons
#endif
#endif
-/* Rename FROM to TO, copying if TO is a link.
- Return 0 if ok, -1 if error. */
+#if !defined (_WIN32) || defined (__CYGWIN32__)
+/* Try to preserve the permission bits and ownership of an existing file when
+ rename overwrites it. FD is the file being renamed and TARGET_STAT has the
+ status of the file that was overwritten. */
+static void
+try_preserve_permissions (int fd, struct stat *target_stat)
+{
+ struct stat from_stat;
+ int ret = 0;
+
+ if (fstat (fd, &from_stat) != 0)
+ return;
+
+ int from_mode = from_stat.st_mode & 0777;
+ int to_mode = target_stat->st_mode & 0777;
+
+ /* Fix up permissions before we potentially lose ownership with fchown.
+ Clear the setxid bits because in case the fchown below fails then we don't
+ want to end up with a sxid file owned by the invoking user. If the user
+ hasn't changed or if fchown succeeded, we add back the sxid bits at the
+ end. */
+ if (from_mode != to_mode)
+ fchmod (fd, to_mode);
+
+ /* Fix up ownership, this will clear the setxid bits. */
+ if (from_stat.st_uid != target_stat->st_uid
+ || from_stat.st_gid != target_stat->st_gid)
+ ret = fchown (fd, target_stat->st_uid, target_stat->st_gid);
+
+ /* Fix up the sxid bits if either the fchown wasn't needed or it
+ succeeded. */
+ if (ret == 0)
+ fchmod (fd, target_stat->st_mode & 07777);
+}
+#endif
+
+/* Rename FROM to TO, copying if TO is either a link or is not a regular file.
+ FD is an open file descriptor pointing to FROM that we can use to safely fix
+ up permissions of the file after renaming. TARGET_STAT has the file status
+ that is used to fix up permissions and timestamps after rename. Return 0 if
+ ok, -1 if error and FD is closed before returning. */
int
-smart_rename (const char *from, const char *to, int preserve_dates ATTRIBUTE_UNUSED)
+smart_rename (const char *from, const char *to, int fd ATTRIBUTE_UNUSED,
+ struct stat *target_stat ATTRIBUTE_UNUSED,
+ int preserve_dates ATTRIBUTE_UNUSED)
{
- bfd_boolean exists;
- struct stat s;
int ret = 0;
-
- exists = lstat (to, &s) == 0;
+ bfd_boolean exists = target_stat != NULL;
#if defined (_WIN32) && !defined (__CYGWIN32__)
/* Win32, unlike unix, will not erase `to' in `rename(from, to)' but
@@ -158,36 +196,35 @@ smart_rename (const char *from, const ch
unlink (from);
}
#else
- /* Use rename only if TO is not a symbolic link and has
- only one hard link, and we have permission to write to it. */
+ /* Avoid a full copy and use rename if we can fix up permissions of the
+ file after renaming, i.e.:
+
+ - TO is not a symbolic link
+ - TO is a regular file with only one hard link
+ - We have permission to write to TO
+ - FD is available to safely fix up permissions to be the same as the file
+ we overwrote with the rename.
+
+ Note though that the actual file on disk that TARGET_STAT describes may
+ have changed and we're only trying to preserve the status we know about.
+ At no point do we try to interact with the new file changes, so there can
+ only be two outcomes, i.e. either the external file change survives
+ without knowledge of our change (if it happens after the rename syscall)
+ or our rename and permissions fixup survive without any knowledge of the
+ external change. */
if (! exists
- || (!S_ISLNK (s.st_mode)
- && S_ISREG (s.st_mode)
- && (s.st_mode & S_IWUSR)
- && s.st_nlink == 1)
+ || (fd >= 0
+ && !S_ISLNK (target_stat->st_mode)
+ && S_ISREG (target_stat->st_mode)
+ && (target_stat->st_mode & S_IWUSR)
+ && target_stat->st_nlink == 1)
)
{
ret = rename (from, to);
if (ret == 0)
{
if (exists)
- {
- /* Try to preserve the permission bits and ownership of
- TO. First get the mode right except for the setuid
- bit. Then change the ownership. Then fix the setuid
- bit. We do the chmod before the chown because if the
- chown succeeds, and we are a normal user, we won't be
- able to do the chmod afterward. We don't bother to
- fix the setuid bit first because that might introduce
- a fleeting security problem, and because the chown
- will clear the setuid bit anyhow. We only fix the
- setuid bit if the chown succeeds, because we don't
- want to introduce an unexpected setuid file owned by
- the user running objcopy. */
- chmod (to, s.st_mode & 0777);
- if (chown (to, s.st_uid, s.st_gid) >= 0)
- chmod (to, s.st_mode & 07777);
- }
+ try_preserve_permissions (fd, target_stat);
}
else
{
@@ -203,9 +240,11 @@ smart_rename (const char *from, const ch
non_fatal (_("unable to copy file '%s'; reason: %s"), to, strerror (errno));
if (preserve_dates)
- set_times (to, &s);
+ set_times (to, target_stat);
unlink (from);
}
+ if (fd >= 0)
+ close (fd);
#endif /* _WIN32 && !__CYGWIN32__ */
return ret;

9
binutils.spec
View File

@ -39,7 +39,7 @@
Summary: A GNU collection of binary utilities
Name: binutils%{?name_cross}%{?_with_debug:-debug}
Version: 2.35.1
Release: 27%{?dist}
Release: 28%{?dist}
License: GPLv3+
URL: https://sourceware.org/binutils
@ -324,6 +324,10 @@ Patch33: binutils-DWARF-5-line-number-parsing.patch
# Lifetime: Fixed in 2.36
Patch34: binutils-testsuite-failures.patch
# Purpose: Remove a vulnerability in the smart_rename function.
# Lifetime: Fixed in 2.36
Patch35: binutils-CVE-2021-20197.patch
#----------------------------------------------------------------------------
Provides: bundled(libiberty)
@ -908,6 +912,9 @@ exit 0
#----------------------------------------------------------------------------
%changelog
* Fri Jan 29 2021 Nick Clifton <nickc@redhat.com> - 2.35.1-28
- Fix a vulnerability in the smart_rename function. (#1913744)
* Thu Jan 28 2021 Nick Clifton <nickc@redhat.com> - 2.35.1-27
- Fix failures is gas and ld testsuites.