[gentoo-hardened] Re: -fstack-protector-all used for kernel build

[Peter S. Mazinger]

On Sat, 13 Dec 2003, Peter S. Mazinger wrote:

I do reply to myself ;-)
The attached patch works, the kernel is bootable (in an uClibc env), but 
it is not the optimal version and I do not have a regression test to check 
if it does what it has to do (check the added protection through 
-fstack-protector-all).

Another version would be to #include ../../../../lib/propolice.c in 
arch/i386/boot/compressed/misc.c and make some ifdef in propolice to not 
use panic in misc.c, like in patch2

STANDALONE is defined in misc.c and used only here to omit some parts 
from asm-i386/io.h, it is not present for other archs, so this works only 
for i386.

misc.c supports only puts/error functions that could be used for printing 
some message, and I do not know how to add damaged and func vars to the 
message.

The best version in my opinion would be to change the frogger patch so 
that panic is not used, something more generic, that would also work in 
misc.c for each arch w/o any ifdef.
The patch is needed probably for all archs that have compressed boot 
images (I have the feeling that the error is coming due to the 
fact that inflate.c is included in misc.c).

Could some kernel guru check if the patch(es) is/are good, and if the 
protection is achieved?

Thanks, Peter

> Hello!
>
> I am trying to build a kernel-2.4.23 with stack protector enabled using
> gcc-3.3.2, propolice 3.3-5 and frogger's patch (needs some cleanup in
> propolice.c:
> 1 warning can be solved by adding #include <linux/kernel.h> (for panic)
> the other is:
> warning: octal escape sequence out of range
> warning: multi-character character constant
>
> I do not understand what the warning means (gcc-2.96 has another warning),
> it happens for the line
> int __guard  = '\0\0\n\777';
> How to correct this?
>
> I tried to add -fstack-protector-all and -fforce-addr (like in
> hardened-gcc), but -fforce-addr does not work at all
> (assembler definition of BUG() in asm-i386/page.h, produces the warning
> below in blkdev.h, if I change 1 to 0, to get the simplified version of
> BUG(), then the blkdev.h warning is gone), but after that the assembler
> usage in random.c/sched.c produces:
>
> warning: asm operand 1 probably doesn't match constraints
> error: impossible constraint in `asm'
>
> and exits (make -s bzImage)
>
> Now back to frogger's patch and -fstack-protector -fstack-protector-all
>
> Warnings due to gcc-3.3 usage (not present for gcc-2.95/96)
> vt.c: In function `do_kdsk_ioctl':
> vt.c:166: warning: comparison is always false due to limited range of data type
> vt.c: In function `do_kdgkb_ioctl':
> vt.c:283: warning: comparison is always false due to limited range of data type
> keyboard.c: In function `do_fn':
> keyboard.c:640: warning: comparison is always true due to limited range of data type
> string.c:384: warning: conflicting types for built-in function `bcopy'
>
> see above
> propolice.c:8:15: warning: octal escape sequence out of range
> propolice.c:8:15: warning: multi-character character constant
>
> Warning due to gcc-3.3 usage (not present for gcc-2.95/96)
> process.c: In function `machine_restart':
> process.c:427: warning: use of memory input without lvalue in asm operand 0 is deprecated
>
> My problem:
> misc.o(.text+0xb): In function `huft_build':
> : undefined reference to `__guard'
> misc.o(.text+0x4e8): In function `huft_build':
> : undefined reference to `__guard'
> misc.o(.text+0x4fb): In function `huft_build':
> : undefined reference to `__stack_smash_handler'
> misc.o(.text+0x511): In function `huft_free':
> : undefined reference to `__guard'
> misc.o(.text+0x53a): In function `huft_free':
> : undefined reference to `__guard'
> misc.o(.text+0x549): In function `huft_free':
> : undefined reference to `__stack_smash_handler'
> misc.o(.text+0x55c): In function `inflate_codes':
> : undefined reference to `__guard'
> misc.o(.text+0x911): In function `inflate_codes':
> : undefined reference to `__guard'
> misc.o(.text+0x921): In function `inflate_codes':
> : undefined reference to `__stack_smash_handler'
> misc.o(.text+0x93d): In function `inflate_stored':
> : undefined reference to `__guard'
> misc.o(.text+0xa9a): In function `inflate_stored':
> : undefined reference to `__guard'
> misc.o(.text+0xaa9): In function `inflate_stored':
> : undefined reference to `__stack_smash_handler'
> misc.o(.text+0xac5): In function `inflate_fixed':
> : undefined reference to `__guard'
> misc.o(.text+0xc19): In function `inflate_fixed':
> : undefined reference to `__guard'
> misc.o(.text+0xc2c): In function `inflate_fixed':
> : undefined reference to `__stack_smash_handler'
> misc.o(.text+0xc46): In function `inflate_dynamic':
> : undefined reference to `__guard'
> misc.o(.text+0x11b4): In function `inflate_dynamic':
> : undefined reference to `__guard'
> misc.o(.text+0x11c7): In function `inflate_dynamic':
> : undefined reference to `__stack_smash_handler'
> misc.o(.text+0x11df): In function `inflate_block':
> : undefined reference to `__guard'
> misc.o(.text+0x12bc): In function `inflate_block':
> : undefined reference to `__guard'
> misc.o(.text+0x12cb): In function `inflate_block':
> : undefined reference to `__stack_smash_handler'
> misc.o(.text+0x12eb): In function `inflate':
> : undefined reference to `__guard'
> misc.o(.text+0x136f): In function `inflate':
> : undefined reference to `__guard'
> misc.o(.text+0x137f): In function `inflate':
> : undefined reference to `__stack_smash_handler'
> misc.o(.text+0x13a3): In function `makecrc':
> : undefined reference to `__guard'
> misc.o(.text+0x1425): In function `makecrc':
> : undefined reference to `__stack_smash_handler'
> misc.o(.text+0x143a): In function `gunzip':
> : undefined reference to `__guard'
> misc.o(.text+0x18b0): In function `gunzip':
> : undefined reference to `__guard'
> misc.o(.text+0x18bf): In function `gunzip':
> : undefined reference to `__stack_smash_handler'
> misc.o(.text+0x18d1): In function `malloc':
> : undefined reference to `__guard'
> misc.o(.text+0x192d): In function `malloc':
> : undefined reference to `__guard'
> misc.o(.text+0x193c): In function `malloc':
> : undefined reference to `__stack_smash_handler'
> misc.o(.text+0x194d): In function `free':
> : undefined reference to `__guard'
> misc.o(.text+0x1964): In function `free':
> : undefined reference to `__stack_smash_handler'
> misc.o(.text+0x1972): In function `gzip_mark':
> : undefined reference to `__guard'
> misc.o(.text+0x1989): In function `gzip_mark':
> : undefined reference to `__guard'
> misc.o(.text+0x1998): In function `gzip_mark':
> : undefined reference to `__stack_smash_handler'
> misc.o(.text+0x19a7): In function `gzip_release':
> : undefined reference to `__guard'
> misc.o(.text+0x19c9): In function `gzip_release':
> : undefined reference to `__stack_smash_handler'
> misc.o(.text+0x19d7): In function `scroll':
> : undefined reference to `__guard'
> misc.o(.text+0x1a41): In function `scroll':
> : undefined reference to `__guard'
> misc.o(.text+0x1a50): In function `scroll':
> : undefined reference to `__stack_smash_handler'
> misc.o(.text+0x1a61): In function `puts':
> : undefined reference to `__guard'
> misc.o(.text+0x1b08): In function `puts':
> : undefined reference to `__guard'
> misc.o(.text+0x1b17): In function `puts':
> : undefined reference to `__stack_smash_handler'
> misc.o(.text+0x1b2c): In function `memset':
> : undefined reference to `__guard'
> misc.o(.text+0x1b52): In function `memset':
> : undefined reference to `__guard'
> misc.o(.text+0x1b61): In function `memset':
> : undefined reference to `__stack_smash_handler'
> misc.o(.text+0x1b76): In function `memcpy':
> : undefined reference to `__guard'
> misc.o(.text+0x1ba1): In function `memcpy':
> : undefined reference to `__guard'
> misc.o(.text+0x1bb0): In function `memcpy':
> : undefined reference to `__stack_smash_handler'
> misc.o(.text+0x1bc1): In function `fill_inbuf':
> : undefined reference to `__guard'
> misc.o(.text+0x1c06): In function `fill_inbuf':
> : undefined reference to `__guard'
> misc.o(.text+0x1c15): In function `fill_inbuf':
> : undefined reference to `__stack_smash_handler'
> misc.o(.text+0x1c2c): In function `flush_window_low':
> : undefined reference to `__guard'
> misc.o(.text+0x1c91): In function `flush_window_low':
> : undefined reference to `__guard'
> misc.o(.text+0x1ca0): In function `flush_window_low':
> : undefined reference to `__stack_smash_handler'
> misc.o(.text+0x1cb9): In function `flush_window_high':
> : undefined reference to `__guard'
> misc.o(.text+0x1d2d): In function `flush_window_high':
> : undefined reference to `__guard'
> misc.o(.text+0x1d3c): In function `flush_window_high':
> : undefined reference to `__stack_smash_handler'
> misc.o(.text+0x1d4c): In function `flush_window':
> : undefined reference to `__guard'
> misc.o(.text+0x1d6d): In function `flush_window':
> : undefined reference to `__guard'
> misc.o(.text+0x1d7c): In function `flush_window':
> : undefined reference to `__stack_smash_handler'
> misc.o(.text+0x1d8b): In function `error':
> : undefined reference to `__guard'
> misc.o(.text+0x1db9): In function `setup_normal_output_buffer':
> : undefined reference to `__guard'
> misc.o(.text+0x1e01): In function `setup_normal_output_buffer':
> : undefined reference to `__guard'
> misc.o(.text+0x1e10): In function `setup_normal_output_buffer':
> : undefined reference to `__stack_smash_handler'
> misc.o(.text+0x1e29): In function `setup_output_buffer_if_we_run_high':
> : undefined reference to `__guard'
> misc.o(.text+0x1ed4): In function `setup_output_buffer_if_we_run_high':
> : undefined reference to `__guard'
> misc.o(.text+0x1ee3): In function `setup_output_buffer_if_we_run_high':
> : undefined reference to `__stack_smash_handler'
> misc.o(.text+0x1ef2): In function `close_output_buffer_if_we_run_high':
> : undefined reference to `__guard'
> misc.o(.text+0x1f34): In function `close_output_buffer_if_we_run_high':
> : undefined reference to `__guard'
> misc.o(.text+0x1f43): In function `close_output_buffer_if_we_run_high':
> : undefined reference to `__stack_smash_handler'
> misc.o(.text+0x1f52): In function `decompress_kernel':
> : undefined reference to `__guard'
> misc.o(.text+0x2002): In function `decompress_kernel':
> : undefined reference to `__guard'
> misc.o(.text+0x2011): In function `decompress_kernel':
> : undefined reference to `__stack_smash_handler'
> make[2]: *** [bvmlinux] Error 1
> make[1]: *** [compressed/bvmlinux] Error 2
> make: *** [bzImage] Error 2
>
> This does not happen for only using -fstack-protector.
>
> Can this be solved? Or otherway round, would the -fstack-protector-all
> enhance kernel security?
>
> Thanks, Peter
>
>

-- 
Peter S. Mazinger <ps.m@×××.net>   ID: 0xA5F059F2    NIC: IXUYHSKQLI
Key fingerprint = 92A4 31E1 56BC 3D5A 2D08  BB6E C389 975E A5F0 59F2

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