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authorFlorian Weimer <fweimer@redhat.com>2017-03-02 14:44:28 +0100
committerFlorian Weimer <fweimer@redhat.com>2017-03-02 14:44:28 +0100
commit2d6ab5df3b675e96ee587ae6a8c2ce004c6b1ba9 (patch)
tree1106f82144a37c4e26b4f004208b6a76d460eedd
parent9090848d0607e93fb08a1d68d9f263846ee33f02 (diff)
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Document and fix --enable-bind-now [BZ #21015]
-rw-r--r--ChangeLog17
-rw-r--r--INSTALL6
-rw-r--r--Makeconfig7
-rw-r--r--Makerules9
-rw-r--r--iconvdata/Makefile5
-rw-r--r--manual/install.texi6
-rw-r--r--sysdeps/unix/sysv/linux/alpha/localplt.data2
-rw-r--r--sysdeps/unix/sysv/linux/i386/localplt.data2
-rw-r--r--sysdeps/x86_64/localplt.data2
9 files changed, 47 insertions, 9 deletions
diff --git a/ChangeLog b/ChangeLog
index a587b9a2a5..bed3bd1e5c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,20 @@
+2017-03-02 Florian Weimer <fweimer@redhat.com>
+
+ [BZ #21015]
+ * manual/install.texi (Configuring and compiling): Document
+ --enable-bind-now.
+ * Makeconfig [bind-now] (LDFLAGS-lib.so): Set.
+ (build-shlib-helper): Use $(LDFLAGS-lib.so).
+ (format.lds): Likewise.
+ [bind-now] (LDFLAGS-c.so): Remove.
+ * sysdeps/x86_64/localplt.data (libm.so): matherr relocation can
+ be R_X86_64_GLOB_DAT.
+ * sysdeps/unix/sysv/linux/i386/localplt.data (libm.so): matherr
+ relocation can be R_386_GLOB_DAT.
+ * sysdeps/unix/sysv/linux/alpha/localplt.data (libm.so): matherr
+ relocaiton can be R_ALPHA_GLOB_DAT.
+ * iconvdata/Makefile [bind-now] (LDFLAGS.so): Add -Wl,-z,now.
+
2017-03-01 Zack Weinberg <zackw@panix.com>
* include/libc-pointer-arith.h: New file. Define
diff --git a/INSTALL b/INSTALL
index 3b3fd121b2..e77cb2d4e2 100644
--- a/INSTALL
+++ b/INSTALL
@@ -146,6 +146,12 @@ will be used, and CFLAGS sets optimization options for the compiler.
of routines called directly from assembler are excluded from this
protection.
+'--enable-bind-now'
+ Disable lazy binding for installed shared objects. This provides
+ additional security hardening because it enables full RELRO and a
+ read-only global offset table (GOT), at the cost of slightly
+ increased program load times.
+
'--enable-pt_chown'
The file 'pt_chown' is a helper binary for 'grantpt' (*note
Pseudo-Terminals: Allocation.) that is installed setuid root to fix
diff --git a/Makeconfig b/Makeconfig
index 97a15b569e..1c815113b9 100644
--- a/Makeconfig
+++ b/Makeconfig
@@ -386,6 +386,13 @@ LDFLAGS.so += $(hashstyle-LDFLAGS)
LDFLAGS-rtld += $(hashstyle-LDFLAGS)
endif
+# If lazy relocations are disabled, add the -z now flag. Use
+# LDFLAGS-lib.so instead of LDFLAGS.so, to avoid adding the flag to
+# test modules.
+ifeq ($(bind-now),yes)
+LDFLAGS-lib.so += -Wl,-z,now
+endif
+
# Command to run after every final link (executable or shared object).
# This is invoked with $(call after-link,...), so it should operate on
# the file $1. This can be set to do some sort of post-processing on
diff --git a/Makerules b/Makerules
index e9194e54cf..7f0eef8096 100644
--- a/Makerules
+++ b/Makerules
@@ -588,7 +588,7 @@ $(LINK.o) -shared -static-libgcc -Wl,-O1 $(sysdep-LDFLAGS) \
$(extra-B-$(@F:lib%.so=%).so) -B$(csu-objpfx) \
$(extra-B-$(@F:lib%.so=%).so) $(load-map-file) \
-Wl,-soname=lib$(libprefix)$(@F:lib%.so=%).so$($(@F)-version) \
- $(LDFLAGS.so) $(LDFLAGS-$(@F:lib%.so=%).so) \
+ $(LDFLAGS.so) $(LDFLAGS-lib.so) $(LDFLAGS-$(@F:lib%.so=%).so) \
-L$(subst :, -L,$(rpath-link)) -Wl,-rpath-link=$(rpath-link)
endef
@@ -686,10 +686,6 @@ LDFLAGS-c.so = -nostdlib -nostartfiles
LDLIBS-c.so += $(libc.so-gnulib)
# Give libc.so an entry point and make it directly runnable itself.
LDFLAGS-c.so += -e __libc_main
-# If lazy relocation is disabled add the -z now flag.
-ifeq ($(bind-now),yes)
-LDFLAGS-c.so += -Wl,-z,now
-endif
# Pre-link the objects of libc_pic.a so that we can locally resolve
# COMMON symbols before we link against ld.so. This is because ld.so
# contains some of libc_pic.a already, which will prevent the COMMONs
@@ -1104,7 +1100,8 @@ $(common-objpfx)format.lds: $(..)scripts/output-format.sed \
ifneq (unknown,$(output-format))
echo > $@.new 'OUTPUT_FORMAT($(output-format))'
else
- $(LINK.o) -shared $(sysdep-LDFLAGS) $(rtld-LDFLAGS) $(LDFLAGS.so) \
+ $(LINK.o) -shared $(sysdep-LDFLAGS) $(rtld-LDFLAGS) \
+ $(LDFLAGS.so) $(LDFLAGS-lib.so) \
-x c /dev/null -o $@.so -Wl,--verbose -v 2>&1 \
| sed -n -f $< > $@.new
test -s $@.new
diff --git a/iconvdata/Makefile b/iconvdata/Makefile
index 04157b25c5..e4845871f5 100644
--- a/iconvdata/Makefile
+++ b/iconvdata/Makefile
@@ -63,6 +63,11 @@ modules := ISO8859-1 ISO8859-2 ISO8859-3 ISO8859-4 ISO8859-5 \
MAC-CENTRALEUROPE KOI8-RU ISO8859-9E \
CP770 CP771 CP772 CP773 CP774
+# If lazy binding is disabled, use BIND_NOW for the gconv modules.
+ifeq ($(bind-now),yes)
+LDFLAGS.so += -Wl,-z,now
+endif
+
modules.so := $(addsuffix .so, $(modules))
ifeq (yes,$(build-shared))
diff --git a/manual/install.texi b/manual/install.texi
index 266add8ba9..3398cfab02 100644
--- a/manual/install.texi
+++ b/manual/install.texi
@@ -175,6 +175,12 @@ options to detect stack overruns. Only the dynamic linker and a small
number of routines called directly from assembler are excluded from this
protection.
+@item --enable-bind-now
+Disable lazy binding for installed shared objects. This provides
+additional security hardening because it enables full RELRO and a
+read-only global offset table (GOT), at the cost of slightly increased
+program load times.
+
@pindex pt_chown
@findex grantpt
@item --enable-pt_chown
diff --git a/sysdeps/unix/sysv/linux/alpha/localplt.data b/sysdeps/unix/sysv/linux/alpha/localplt.data
index cca17f1e34..1f0e3b494e 100644
--- a/sysdeps/unix/sysv/linux/alpha/localplt.data
+++ b/sysdeps/unix/sysv/linux/alpha/localplt.data
@@ -20,7 +20,7 @@ libc.so: free + RELA R_ALPHA_GLOB_DAT
libc.so: malloc + RELA R_ALPHA_GLOB_DAT
libc.so: memalign + RELA R_ALPHA_GLOB_DAT
libc.so: realloc + RELA R_ALPHA_GLOB_DAT
-libm.so: matherr
+libm.so: matherr + RELA R_ALPHA_GLOB_DAT
# We used to offer inline functions that used this, so it must be exported.
# Ought to reorg things such that carg isn't thus forced to use a plt.
libm.so: __atan2
diff --git a/sysdeps/unix/sysv/linux/i386/localplt.data b/sysdeps/unix/sysv/linux/i386/localplt.data
index 2c2584956d..8ea4333846 100644
--- a/sysdeps/unix/sysv/linux/i386/localplt.data
+++ b/sysdeps/unix/sysv/linux/i386/localplt.data
@@ -6,7 +6,7 @@ libc.so: free + REL R_386_GLOB_DAT
libc.so: malloc + REL R_386_GLOB_DAT
libc.so: memalign + REL R_386_GLOB_DAT
libc.so: realloc + REL R_386_GLOB_DAT
-libm.so: matherr
+libm.so: matherr + REL R_386_GLOB_DAT
# The main malloc is interposed into the dynamic linker, for
# allocations after the initial link (when dlopen is used).
ld.so: malloc + REL R_386_GLOB_DAT
diff --git a/sysdeps/x86_64/localplt.data b/sysdeps/x86_64/localplt.data
index 014a9f4554..a1840cff31 100644
--- a/sysdeps/x86_64/localplt.data
+++ b/sysdeps/x86_64/localplt.data
@@ -8,7 +8,7 @@ libc.so: free + RELA R_X86_64_GLOB_DAT
libc.so: malloc + RELA R_X86_64_GLOB_DAT
libc.so: memalign + RELA R_X86_64_GLOB_DAT
libc.so: realloc + RELA R_X86_64_GLOB_DAT
-libm.so: matherr
+libm.so: matherr + RELA R_X86_64_GLOB_DAT
# The main malloc is interposed into the dynamic linker, for
# allocations after the initial link (when dlopen is used).
ld.so: malloc + RELA R_X86_64_GLOB_DAT