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acpi: make bios_linker_loader_add_checksum() API offset based

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It should help to make clear that bios_linker works in terms
of offsets within a file. Also it should prevent mistakes
where user passes as arguments pointers to unrelated to file blobs.

While at it, considering that it's a ACPI checksum and
it's initial value must be 0, move checksum field zeroing
into bios_linker_loader_add_checksum() instead of doing it
at every call site manually before bios_linker_loader_add_checksum()
is called.

In addition add extra boundary checks.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Igor Mammedov 2016-05-19 15:19:30 +02:00 committed by Michael S. Tsirkin
parent 4678124bb9
commit 28213cb6a6
5 changed files with 22 additions and 33 deletions
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5
hw/acpi/aml-build.c
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@ -1493,6 +1493,8 @@ build_header(BIOSLinker *linker, GArray *table_data,
AcpiTableHeader *h, const char *sig, int len, uint8_t rev,
const char *oem_id, const char *oem_table_id)
{
unsigned tbl_offset = (char *)h - table_data->data;
unsigned checksum_offset = (char *)&h->checksum - table_data->data;
memcpy(&h->signature, sig, 4);
h->length = cpu_to_le32(len);
h->revision = rev;
@ -1513,10 +1515,9 @@ build_header(BIOSLinker *linker, GArray *table_data,
h->oem_revision = cpu_to_le32(1);
memcpy(h->asl_compiler_id, ACPI_BUILD_APPNAME4, 4);
h->asl_compiler_revision = cpu_to_le32(1);
h->checksum = 0;
/* Checksum to be filled in by Guest linker */
bios_linker_loader_add_checksum(linker, ACPI_BUILD_TABLE_FILE,
h, len, &h->checksum);
tbl_offset, len, checksum_offset);
}
void *acpi_data_push(GArray *table_data, unsigned size)

36
hw/acpi/bios-linker-loader.c
View File

@ -189,8 +189,8 @@ void bios_linker_loader_alloc(BIOSLinker *linker,
}
/*
* bios_linker_loader_add_checksum: ask guest to add checksum of file data
* into (same) file at the specified pointer.
* bios_linker_loader_add_checksum: ask guest to add checksum of ACPI
* table in the specified file at the specified offset.
*
* Checksum calculation simply sums -X for each byte X in the range
* using 8-bit math (i.e. ACPI checksum).
@ -198,35 +198,25 @@ void bios_linker_loader_alloc(BIOSLinker *linker,
* @linker: linker object instance
* @file: file that includes the checksum to be calculated
* and the data to be checksummed
* @start, @size: range of data to checksum
* @checksum: location of the checksum to be patched within file blob
*
* Notes:
* - checksum byte initial value must have been pushed into blob
* associated with @file and reside at address @checksum.
* - @size bytes must have been pushed into blob associated wtih @file
* and reside at address @start.
* - Guest calculates checksum of specified range of data, result is added to
* initial value at @checksum into copy of @file in Guest memory.
* - Range might include the checksum itself.
* - To avoid confusion, caller must always put 0x0 at @checksum.
* - @file must be loaded into Guest memory using bios_linker_loader_alloc
* @start_offset, @size: range of data in the file to checksum,
* relative to the start of file blob
* @checksum_offset: location of the checksum to be patched within file blob,
* relative to the start of file blob
*/
void bios_linker_loader_add_checksum(BIOSLinker *linker, const char *file_name,
void *start, unsigned size,
uint8_t *checksum)
unsigned start_offset, unsigned size,
unsigned checksum_offset)
{
BiosLinkerLoaderEntry entry;
const BiosLinkerFileEntry *file = bios_linker_find_file(linker, file_name);
ptrdiff_t checksum_offset = (gchar *)checksum - file->blob->data;
ptrdiff_t start_offset = (gchar *)start - file->blob->data;
assert(checksum_offset >= 0);
assert(start_offset >= 0);
assert(checksum_offset + 1 <= file->blob->len);
assert(file);
assert(start_offset < file->blob->len);
assert(start_offset + size <= file->blob->len);
assert(*checksum == 0x0);
assert(checksum_offset >= start_offset);
assert(checksum_offset + 1 <= start_offset + size);
*(file->blob->data + checksum_offset) = 0;
memset(&entry, 0, sizeof entry);
strncpy(entry.cksum.file, file_name, sizeof entry.cksum.file - 1);
entry.command = cpu_to_le32(BIOS_LINKER_LOADER_COMMAND_ADD_CHECKSUM);

5
hw/arm/virt-acpi-build.c
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@ -374,11 +374,10 @@ build_rsdp(GArray *rsdp_table, BIOSLinker *linker, unsigned rsdt_tbl_offset)
ACPI_BUILD_RSDP_FILE, rsdt_pa_offset, rsdt_pa_size,
ACPI_BUILD_TABLE_FILE, rsdt_tbl_offset);
rsdp->checksum = 0;
/* Checksum to be filled by Guest linker */
bios_linker_loader_add_checksum(linker, ACPI_BUILD_RSDP_FILE,
rsdp, sizeof *rsdp,
&rsdp->checksum);
(char *)rsdp - rsdp_table->data, sizeof *rsdp,
(char *)&rsdp->checksum - rsdp_table->data);
return rsdp_table;
}

5
hw/i386/acpi-build.c
View File

@ -2458,11 +2458,10 @@ build_rsdp(GArray *rsdp_table, BIOSLinker *linker, unsigned rsdt_tbl_offset)
ACPI_BUILD_RSDP_FILE, rsdt_pa_offset, rsdt_pa_size,
ACPI_BUILD_TABLE_FILE, rsdt_tbl_offset);
rsdp->checksum = 0;
/* Checksum to be filled by Guest linker */
bios_linker_loader_add_checksum(linker, ACPI_BUILD_RSDP_FILE,
rsdp, sizeof *rsdp,
&rsdp->checksum);
(char *)rsdp - rsdp_table->data, sizeof *rsdp,
(char *)&rsdp->checksum - rsdp_table->data);
return rsdp_table;
}

4
include/hw/acpi/bios-linker-loader.h
View File

@ -17,8 +17,8 @@ void bios_linker_loader_alloc(BIOSLinker *linker,
bool alloc_fseg);
void bios_linker_loader_add_checksum(BIOSLinker *linker, const char *file,
void *start, unsigned size,
uint8_t *checksum);
unsigned start_offset, unsigned size,
unsigned checksum_offset);
void bios_linker_loader_add_pointer(BIOSLinker *linker,
const char *dest_file,