proxmox-mirrors/efi-boot-shim
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generate_hash(): make check_size() set an error, and verify SecDir size.

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Currently generate_hash() attempts to include any trailing data at the
end of the binary in the resulting digest, but it won't include such
data if the size computed is wrong because context->SecDir->Size is
invalid.  In this case the return code is EFI_SUCCESS, and the hash will
match any a binary as if the Attribute Certificate Table and anything
after it are missing.  This is wrong.

Signed-off-by: Peter Jones <pjones@redhat.com>
This commit is contained in:
Peter Jones 2016-10-17 16:16:17 -04:00
parent 431d893b41
commit 03b9f800b9
1 changed files with 9 additions and 0 deletions
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9
shim.c
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@ -686,12 +686,14 @@ static BOOLEAN secure_mode (void)
#define check_size_line(data, datasize_in, hashbase, hashsize, l) ({ \
if ((unsigned long)hashbase > \
(unsigned long)data + datasize_in) { \
status = EFI_INVALID_PARAMETER; \
perror(L"shim.c:%d Invalid hash base 0x%016x\n", l, \
hashbase); \
goto done; \
} \
if ((unsigned long)hashbase + hashsize > \
(unsigned long)data + datasize_in) { \
status = EFI_INVALID_PARAMETER; \
perror(L"shim.c:%d Invalid hash size 0x%016x\n", l, \
hashsize); \
goto done; \
@ -887,6 +889,13 @@ static EFI_STATUS generate_hash (char *data, unsigned int datasize_in,
if (datasize > SumOfBytesHashed) {
hashbase = data + SumOfBytesHashed;
hashsize = datasize - context->SecDir->Size - SumOfBytesHashed;
if ((datasize - SumOfBytesHashed < context->SecDir->Size) ||
(SumOfBytesHashed - hashsize != context->SecDir->VirtualAddress)) {
perror(L"Malformed binary after Attribute Certificate Table\n");
status = EFI_INVALID_PARAMETER;
goto done;
}
check_size(data, datasize_in, hashbase, hashsize);
if (!(Sha256Update(sha256ctx, hashbase, hashsize)) ||