On Wed, 2019-06-26 at 09:52 +0200, Sascha Hauer wrote:
> On Wed, Jun 26, 2019 at 06:58:51AM +0200, Rouven Czerwinski wrote:
> > Add piggydata verification before the ARM uncompress function.
> > This calculates the sha256sum of the compressed barebox binary and
> > only
> > continues if the builtin sha256sum matches the calculated
> > sha256sum.
> >
> > Signed-off-by: Rouven Czerwinski <r.czerwinski@xxxxxxxxxxxxxx>
> > ---
> > arch/arm/cpu/uncompress.c | 18 +++++++++++++++++-
> > 1 file changed, 17 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/arm/cpu/uncompress.c b/arch/arm/cpu/uncompress.c
> > index e527165..ce5f2c1 100644
> > --- a/arch/arm/cpu/uncompress.c
> > +++ b/arch/arm/cpu/uncompress.c
> > @@ -42,14 +42,18 @@ unsigned long free_mem_end_ptr;
> > extern unsigned char input_data[];
> > extern unsigned char input_data_end[];
> >
> > +extern unsigned char sha_sum[];
> > +extern unsigned char sha_sum_end[];
> > +
> > void __noreturn barebox_multi_pbl_start(unsigned long membase,
> > unsigned long memsize, void *boarddata)
> > {
> > - uint32_t pg_len, uncompressed_len;
> > + uint32_t pg_len, uncompressed_len, pbl_hash_len;
> > void __noreturn (*barebox)(unsigned long, unsigned long, void
> > *);
> > unsigned long endmem = membase + memsize;
> > unsigned long barebox_base;
> > void *pg_start, *pg_end;
> > + void *pbl_hash_start, *pbl_hash_end;
> > unsigned long pc = get_pc();
> >
> > pg_start = input_data + global_variable_offset();
> > @@ -92,6 +96,18 @@ void __noreturn barebox_multi_pbl_start(unsigned
> > long membase,
> > pr_debug("uncompressing barebox binary at 0x%p (size 0x%08x) to
> > 0x%08lx (uncompressed size: 0x%08x)\n",
> > pg_start, pg_len, barebox_base,
> > uncompressed_len);
> >
> > + if (IS_ENABLED(CONFIG_PBL_VERIFY_PIGGY)) {
> > + pbl_hash_start = sha_sum + global_variable_offset();
> > + pbl_hash_end = sha_sum_end + global_variable_offset();
> > + pbl_hash_len = pbl_hash_end - pbl_hash_start;
> > + if (pbl_barebox_verify(pg_start, pg_len,
> > pbl_hash_start,
> > + pbl_hash_len) != 0) {
> > + putc_ll('!');
> > + pr_err("hash mismatch, refusing to
> > decompress");
> > + panic("hash mismatch, refusing to decompress");
>
> Isn't printing the string in panic() enough?
Unfortunately not, pbl/misc.c defines panic as:
void __noreturn panic(const char *fmt, ...)
{
while(1);
}
Rouven Czerwinski
--
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