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Code Issues Releases Activity

Add RELRO build knob, default to enabled

Browse Source 
Note that lld enables relro by default, so that we already had either
partial or full RELRO, depending on the state of the BIND_NOW knob.

Add a RELRO knob so that the option can be disabled if desired, and so
that builds using the GNU toolchain are equivalent to those using the
standard Clang/LLVM toolchain.

Reviewed by:	markj
MFC after:	3 weeks
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D35545
This commit is contained in:
Ed Maste 2022-06-22 08:58:04 -04:00
parent 5d6894bd66
commit 2f3a961487
6 changed files with 27 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
share/mk/bsd.lib.mk
View File

@ -79,6 +79,11 @@ TAG_ARGS= -T ${TAGS:[*]:S/ /,/g}
.if ${MK_BIND_NOW} != "no"
LDFLAGS+= -Wl,-znow
.endif
.if ${MK_RELRO} == "no"
LDFLAGS+= -Wl,-znorelro
.else
LDFLAGS+= -Wl,-zrelro
.endif
.if ${MK_RETPOLINE} != "no"
.if ${COMPILER_FEATURES:Mretpoline} && ${LINKER_FEATURES:Mretpoline}
CFLAGS+= -mretpoline

1
share/mk/bsd.opts.mk
View File

@ -64,6 +64,7 @@ __DEFAULT_YES_OPTIONS = \
NIS \
NLS \
OPENSSH \
RELRO \
SSP \
TESTS \
TOOLCHAIN \

5
share/mk/bsd.prog.mk
View File

@ -41,6 +41,11 @@ MK_DEBUG_FILES= no
.if ${MK_BIND_NOW} != "no"
LDFLAGS+= -Wl,-znow
.endif
.if ${MK_RELRO} == "no"
LDFLAGS+= -Wl,-znorelro
.else
LDFLAGS+= -Wl,-zrelro
.endif
.if ${MK_PIE} != "no"
# Static PIE is not yet supported/tested.
.if !defined(NO_SHARED) || ${NO_SHARED:tl} == "no"

4
tools/build/options/WITHOUT_RELRO Normal file
View File

@ -0,0 +1,4 @@
Do not apply the Relocation Read-Only (RELRO) vulnerability mitigation.
See also the
.Va BIND_NOW
option.

7
tools/build/options/WITH_BIND_NOW
View File

@ -3,3 +3,10 @@ Build all binaries with the
.Dv DF_BIND_NOW
flag set to indicate that the run-time loader should perform all relocation
processing at process startup rather than on demand.
The combination of the
.Va BIND_NOW
and
.Va RELRO
options provide "full" Relocation Read-Only (RELRO) support.
With full RELRO the entire GOT is made read-only after performing relocation at
startup, avoiding GOT overwrite attacks.

5
tools/build/options/WITH_RELRO Normal file
View File

@ -0,0 +1,5 @@
Build all binaries with the Relocation Read-Only (RELRO) vulnerability
mitigation applied.
See also the
.Va BIND_NOW
option.