On Sat, May 06, 2017 at 01:34:49PM -0400, Brian Gerst wrote: > On Fri, May 5, 2017 at 5:26 AM, Gary Lin <g...@suse.com> wrote: > > This is a different approach to replace my previous implementation of > > Security Version(*). Instead of using the fields in the PE/COFF header, > > this commit adds secdata_offset in the setup header for the file offset > > of secdata. Currently, the secdata section contains the signer's name, > > the distro version, and the security version as defined in the wiki page. > > Since we don't rely on the PE/COFF header anymore, the size of signer is > > increased to 8 bytes to store more characters. > > > > Since this is just a tentative patch, I haven't started the other parts > > (shim and mokutil) yet, and it's flexible to change. Any comment and > > suggestion are welcome. > > > > (*) https://github.com/lcp/shim/wiki/Security-Version > > > > Cc: Ard Biesheuvel <ard.biesheu...@linaro.org> > > Cc: "H. Peter Anvin" <h...@zytor.com> > > Cc: Thomas Gleixner <t...@linutronix.de> > > Cc: Ingo Molnar <mi...@redhat.com> > > Cc: Joey Lee <j...@suse.com> > > Signed-off-by: Gary Lin <g...@suse.com> > > --- > > arch/x86/Kconfig | 14 ++++++++++++++ > > arch/x86/boot/header.S | 15 ++++++++++++++- > > arch/x86/boot/setup.ld | 1 + > > arch/x86/boot/tools/build.c | 11 +++++++++++ > > arch/x86/include/uapi/asm/bootparam.h | 1 + > > 5 files changed, 41 insertions(+), 1 deletion(-) > > > > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > > index 5bbdef151805..09f99cd1e699 100644 > > --- a/arch/x86/Kconfig > > +++ b/arch/x86/Kconfig > > @@ -1817,6 +1817,20 @@ config EFI_MIXED > > > > If unsure, say N. > > > > +config SEC_SIGNER > > + string "The signer name" > > + default "none" > > + > > +config SEC_DISTRO > > + int "The distro version" > > + default 0 > > + range 0 65535 > > + > > +config SEC_VERSION > > + int "The security version" > > + default 0 > > + range 0 65535 > > + > > config SECCOMP > > def_bool y > > prompt "Enable seccomp to safely compute untrusted bytecode" > > diff --git a/arch/x86/boot/header.S b/arch/x86/boot/header.S > > index 3dd5be33aaa7..f751790f1f44 100644 > > --- a/arch/x86/boot/header.S > > +++ b/arch/x86/boot/header.S > > @@ -301,7 +301,7 @@ _start: > > # Part 2 of the header, from the old setup.S > > > > .ascii "HdrS" # header signature > > - .word 0x020d # header version number (>= 0x0105) > > + .word 0x020e # header version number (>= 0x0105) > > # or else old loadlin-1.5 will fail) > > .globl realmode_swtch > > realmode_swtch: .word 0, 0 # default_switch, SETUPSEG > > @@ -552,6 +552,7 @@ pref_address: .quad LOAD_PHYSICAL_ADDR > > # preferred load addr > > > > init_size: .long INIT_SIZE # kernel initialization size > > handover_offset: .long 0 # Filled in by build.c > > +secdata_offset: .long secdata_start > > > > # End of setup header ##################################################### > > > > @@ -629,3 +630,15 @@ die: > > setup_corrupt: > > .byte 7 > > .string "No setup signature found...\n" > > + > > + .section ".secdata", "a" > > +secdata_start: > > +sec_length: > > + .long secdata_end - secdata_start > > +sec_signer: > > + .quad 0 # Filled by build.c > > A more flexible way to do this would be to make sec_signer an offset > to a null-terminated string. That way it can be any length, and you > wouldn't need the build tool hack. > I was thinking about making sec_signer a variable length string and decided to make sec_signer fixed since it's easier to match 2 fixed size variables (just convert them to u32 or u64). Besides, I also want to limit the size of sec_signer because the list of security version will be stored in the NVRAM which is quite limited (Is it possible to limit the length of a string in kconfig?).
If the variable size string makes more sense, I'll update that in v2. Thanks, Gary Lin
