On 2019-02-13 23:15, Hauke Mehrtens wrote: > This will build all executable as Position Independent Executables (PIE) > by default. PIE executable can make full use of Address Space Layout > Randomization (ASLR) because all sections can be placed at random > offsets of the executed program. This makes it harder to exploit bugs > in our binaries. > > This will increase the size of executable, libraries are already build > position independent and their size will not change. > > This increases the size of the resulting images by about 3% on MIPS BE. > I tested this with the default configuration for the lantiq xrx200 > target. > > The size of the initramfs binaries increased by 2.88%: > Without PIE: > 5.303.716 openwrt-lantiq-xrx200-bt_homehub-v5a-initramfs-kernel.bin > With PIE: > 5.456.339 openwrt-lantiq-xrx200-bt_homehub-v5a-initramfs-kernel.bin > > With PIE activated the executable are getting bigger, here are some > examples from the lantiq mips_24kc target: > > Without PIE: > 112.309 /bin/opkg > 299.061 /bin/busybox > 456.549 /usr/sbin/wpad > > With PIE: > 142.496 /bin/opkg (26.87% increase) > 388.404 /bin/busybox (29.87% increase) > 580.128 /usr/sbin/wpad (27.06% increase) > > With PIE activated the sections of the binaries are loaded to > different offsets for each program instance like shown here: > > root@OpenWrt:/# cat /proc/self/maps > 555c4000-55622000 r-xp 00000000 00:02 1030 /bin/busybox > 55631000-55632000 r-xp 0005d000 00:02 1030 /bin/busybox > 55632000-55633000 rwxp 0005e000 00:02 1030 /bin/busybox > 55633000-55634000 rwxp 00000000 00:00 0 > 77ee2000-77f04000 r-xp 00000000 00:02 331 /lib/libgcc_s.so.1 > 77f04000-77f05000 r-xp 00012000 00:02 331 /lib/libgcc_s.so.1 > 77f05000-77f06000 rwxp 00013000 00:02 331 /lib/libgcc_s.so.1 > 77f06000-77f9a000 r-xp 00000000 00:02 329 /lib/libc.so > 77fa9000-77fab000 rwxp 00093000 00:02 329 /lib/libc.so > 77fab000-77fad000 rwxp 00000000 00:00 0 > 7fb26000-7fb47000 rw-p 00000000 00:00 0 [stack] > 7fefb000-7fefc000 r-xp 00000000 00:00 0 > 7ff0a000-7ff0b000 r--p 00000000 00:00 0 [vvar] > 7ff0b000-7ff0c000 r-xp 00000000 00:00 0 [vdso] > root@OpenWrt:/# cat /proc/self/maps > 5561d000-5567b000 r-xp 00000000 00:02 1030 /bin/busybox > 5568a000-5568b000 r-xp 0005d000 00:02 1030 /bin/busybox > 5568b000-5568c000 rwxp 0005e000 00:02 1030 /bin/busybox > 5568c000-5568d000 rwxp 00000000 00:00 0 > 77e8e000-77eb0000 r-xp 00000000 00:02 331 /lib/libgcc_s.so.1 > 77eb0000-77eb1000 r-xp 00012000 00:02 331 /lib/libgcc_s.so.1 > 77eb1000-77eb2000 rwxp 00013000 00:02 331 /lib/libgcc_s.so.1 > 77eb2000-77f46000 r-xp 00000000 00:02 329 /lib/libc.so > 77f55000-77f57000 rwxp 00093000 00:02 329 /lib/libc.so > 77f57000-77f59000 rwxp 00000000 00:00 0 > 7fd1c000-7fd3d000 rw-p 00000000 00:00 0 [stack] > 7fefb000-7fefc000 r-xp 00000000 00:00 0 > 7ff60000-7ff61000 r--p 00000000 00:00 0 [vvar] > 7ff61000-7ff62000 r-xp 00000000 00:00 0 [vdso] > root@OpenWrt:/# > > Signed-off-by: Hauke Mehrtens <ha...@hauke-m.de> > --- > > I would like to get some comments if we should activate PIE by default. > The advantage is that it will be harder to exploit OpenWrt, but on the > other hand the binaries are getting bigger. We could also restrict this > to some CPU types, but as targets share the binaries it is not really > possible to do this based on the target. > > I am not sure if this should go into the next release or wait for later. > > This could also break some packages, as it is possible to activate PIE > by default for some time many bugs are already fixed, but probably not > all of them. I think this is a lot of extra bloat. Maybe we can add a restricted PIE mode where packages can opt-in individually?
- Felix _______________________________________________ openwrt-devel mailing list openwrt-devel@lists.openwrt.org https://lists.openwrt.org/mailman/listinfo/openwrt-devel
