| Message ID | 20190607205147.102904-2-matthewgarrett@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [V2,1/2] Abstract out support for locating an EFI config table | expand |
On Fri, 7 Jun 2019 at 22:52, Matthew Garrett <matthewgarrett@google.com> wrote: > > After the first call to GetEventLog() on UEFI systems using the TCG2 > crypto agile log format, any further log events (other than those > triggered by ExitBootServices()) will be logged in both the main log and > also in the Final Events Log. While the kernel only calls GetEventLog() > immediately before ExitBootServices(), we can't control whether earlier > parts of the boot process have done so. This will result in log entries > that exist in both logs, and so the current approach of simply appending > the Final Event Log to the main log will result in events being > duplicated. > > We can avoid this problem by looking at the size of the Final Event Log > just before we call ExitBootServices() and exporting this to the main > kernel. The kernel can then skip over all events that occured before > ExitBootServices() and only append events that were not also logged to > the main log. > > Signed-off-by: Matthew Garrett <mjg59@google.com> > Reported-by: Joe Richey <joerichey@google.com> > Suggested-by: Joe Richey <joerichey@google.com> > --- > drivers/char/tpm/eventlog/efi.c | 11 ++++++++++- > drivers/firmware/efi/libstub/tpm.c | 30 ++++++++++++++++++++++++++++++ > drivers/firmware/efi/tpm.c | 2 +- > include/linux/efi.h | 1 + > 4 files changed, 42 insertions(+), 2 deletions(-) > > diff --git a/drivers/char/tpm/eventlog/efi.c b/drivers/char/tpm/eventlog/efi.c > index 9179cf6bdee9..be6540f2cb3d 100644 > --- a/drivers/char/tpm/eventlog/efi.c > +++ b/drivers/char/tpm/eventlog/efi.c > @@ -80,6 +80,8 @@ int tpm_read_log_efi(struct tpm_chip *chip) > goto out; > } > > + efi_tpm_final_log_size -= log_tbl->final_events_preboot_size; > + > tmp = krealloc(log->bios_event_log, > log_size + efi_tpm_final_log_size, > GFP_KERNEL); > @@ -90,8 +92,15 @@ int tpm_read_log_efi(struct tpm_chip *chip) > } > > log->bios_event_log = tmp; > + > + /* > + * Copy any of the final events log that didn't also end up in the > + * main log. Events can be logged in both if events are generated > + * between GetEventLog() and ExitBootServices(). > + */ > memcpy((void *)log->bios_event_log + log_size, > - final_tbl->events, efi_tpm_final_log_size); > + final_tbl->events + log_tbl->final_events_preboot_size, > + efi_tpm_final_log_size); > log->bios_event_log_end = log->bios_event_log + > log_size + efi_tpm_final_log_size; > > diff --git a/drivers/firmware/efi/libstub/tpm.c b/drivers/firmware/efi/libstub/tpm.c > index 6b3b507a54eb..eb9af83e4d59 100644 > --- a/drivers/firmware/efi/libstub/tpm.c > +++ b/drivers/firmware/efi/libstub/tpm.c > @@ -64,11 +64,13 @@ void efi_retrieve_tpm2_eventlog(efi_system_table_t *sys_table_arg) > efi_status_t status; > efi_physical_addr_t log_location = 0, log_last_entry = 0; > struct linux_efi_tpm_eventlog *log_tbl = NULL; > + struct efi_tcg2_final_events_table *final_events_table; > unsigned long first_entry_addr, last_entry_addr; > size_t log_size, last_entry_size; > efi_bool_t truncated; > int version = EFI_TCG2_EVENT_LOG_FORMAT_TCG_2; > void *tcg2_protocol = NULL; > + int final_events_size = 0; > > status = efi_call_early(locate_protocol, &tcg2_guid, NULL, > &tcg2_protocol); > @@ -134,8 +136,36 @@ void efi_retrieve_tpm2_eventlog(efi_system_table_t *sys_table_arg) > return; > } > > + /* > + * Figure out whether any events have already been logged to the > + * final events structure, and if so how much space they take up > + */ > + final_events_table = get_efi_config_table(sys_table_arg, > + LINUX_EFI_TPM_FINAL_LOG_GUID); > + if (final_events_table && final_events_table->nr_events) { > + struct tcg_pcr_event2_head *header; > + int offset; > + void *data; > + int event_size; > + int i = final_events_table->nr_events; > + > + data = (void *)final_events_table; > + offset = sizeof(final_events_table->version) + > + sizeof(final_events_table->nr_events); > + > + while (i > 0) { > + header = data + offset + final_events_size; > + event_size = __calc_tpm2_event_size(header, > + (void *)(long)log_location, > + false); > + final_events_size += event_size; > + i--; > + } > + } > + > memset(log_tbl, 0, sizeof(*log_tbl) + log_size); > log_tbl->size = log_size; > + log_tbl->final_events_preboot_size = final_events_size; > log_tbl->version = version; > memcpy(log_tbl->log, (void *) first_entry_addr, log_size); > > diff --git a/drivers/firmware/efi/tpm.c b/drivers/firmware/efi/tpm.c > index 2c912ea08166..0bdceb5913aa 100644 > --- a/drivers/firmware/efi/tpm.c > +++ b/drivers/firmware/efi/tpm.c > @@ -76,7 +76,7 @@ int __init efi_tpm_eventlog_init(void) > goto out; > } > > - tbl_size = tpm2_calc_event_log_size(efi.tpm_final_log > + tbl_size = tpm2_calc_event_log_size((void *)efi.tpm_final_log > + sizeof(final_tbl->version) > + sizeof(final_tbl->nr_events), > final_tbl->nr_events, > diff --git a/include/linux/efi.h b/include/linux/efi.h > index e33c70a52a9d..2a26004a9bdb 100644 > --- a/include/linux/efi.h > +++ b/include/linux/efi.h > @@ -1703,6 +1703,7 @@ struct linux_efi_random_seed { > > struct linux_efi_tpm_eventlog { > u32 size; > + u32 final_events_preboot_size; > u8 version; > u8 log[]; > }; Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
On Fri, Jun 07, 2019 at 01:51:47PM -0700, Matthew Garrett wrote: > After the first call to GetEventLog() on UEFI systems using the TCG2 > crypto agile log format, any further log events (other than those > triggered by ExitBootServices()) will be logged in both the main log and > also in the Final Events Log. While the kernel only calls GetEventLog() > immediately before ExitBootServices(), we can't control whether earlier > parts of the boot process have done so. This will result in log entries > that exist in both logs, and so the current approach of simply appending > the Final Event Log to the main log will result in events being > duplicated. > > We can avoid this problem by looking at the size of the Final Event Log > just before we call ExitBootServices() and exporting this to the main > kernel. The kernel can then skip over all events that occured before > ExitBootServices() and only append events that were not also logged to > the main log. > > Signed-off-by: Matthew Garrett <mjg59@google.com> > Reported-by: Joe Richey <joerichey@google.com> > Suggested-by: Joe Richey <joerichey@google.com> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> /Jarkko
On Fri, Jun 07, 2019 at 11:11:21PM +0200, Ard Biesheuvel wrote:
> Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Ard, is it cool if I include these to my next TPM PR along with the
other Matthew's changes? Just sanity checking given that crossing
subsystems...
/Jarkko
On Thu, 13 Jun 2019 at 16:06, Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com> wrote: > > On Fri, Jun 07, 2019 at 11:11:21PM +0200, Ard Biesheuvel wrote: > > Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> > > Ard, is it cool if I include these to my next TPM PR along with the > other Matthew's changes? Just sanity checking given that crossing > subsystems... > Yes, that is fine.
diff --git a/drivers/char/tpm/eventlog/efi.c b/drivers/char/tpm/eventlog/efi.c index 9179cf6bdee9..be6540f2cb3d 100644 --- a/drivers/char/tpm/eventlog/efi.c +++ b/drivers/char/tpm/eventlog/efi.c @@ -80,6 +80,8 @@ int tpm_read_log_efi(struct tpm_chip *chip) goto out; } + efi_tpm_final_log_size -= log_tbl->final_events_preboot_size; + tmp = krealloc(log->bios_event_log, log_size + efi_tpm_final_log_size, GFP_KERNEL); @@ -90,8 +92,15 @@ int tpm_read_log_efi(struct tpm_chip *chip) } log->bios_event_log = tmp; + + /* + * Copy any of the final events log that didn't also end up in the + * main log. Events can be logged in both if events are generated + * between GetEventLog() and ExitBootServices(). + */ memcpy((void *)log->bios_event_log + log_size, - final_tbl->events, efi_tpm_final_log_size); + final_tbl->events + log_tbl->final_events_preboot_size, + efi_tpm_final_log_size); log->bios_event_log_end = log->bios_event_log + log_size + efi_tpm_final_log_size; diff --git a/drivers/firmware/efi/libstub/tpm.c b/drivers/firmware/efi/libstub/tpm.c index 6b3b507a54eb..eb9af83e4d59 100644 --- a/drivers/firmware/efi/libstub/tpm.c +++ b/drivers/firmware/efi/libstub/tpm.c @@ -64,11 +64,13 @@ void efi_retrieve_tpm2_eventlog(efi_system_table_t *sys_table_arg) efi_status_t status; efi_physical_addr_t log_location = 0, log_last_entry = 0; struct linux_efi_tpm_eventlog *log_tbl = NULL; + struct efi_tcg2_final_events_table *final_events_table; unsigned long first_entry_addr, last_entry_addr; size_t log_size, last_entry_size; efi_bool_t truncated; int version = EFI_TCG2_EVENT_LOG_FORMAT_TCG_2; void *tcg2_protocol = NULL; + int final_events_size = 0; status = efi_call_early(locate_protocol, &tcg2_guid, NULL, &tcg2_protocol); @@ -134,8 +136,36 @@ void efi_retrieve_tpm2_eventlog(efi_system_table_t *sys_table_arg) return; } + /* + * Figure out whether any events have already been logged to the + * final events structure, and if so how much space they take up + */ + final_events_table = get_efi_config_table(sys_table_arg, + LINUX_EFI_TPM_FINAL_LOG_GUID); + if (final_events_table && final_events_table->nr_events) { + struct tcg_pcr_event2_head *header; + int offset; + void *data; + int event_size; + int i = final_events_table->nr_events; + + data = (void *)final_events_table; + offset = sizeof(final_events_table->version) + + sizeof(final_events_table->nr_events); + + while (i > 0) { + header = data + offset + final_events_size; + event_size = __calc_tpm2_event_size(header, + (void *)(long)log_location, + false); + final_events_size += event_size; + i--; + } + } + memset(log_tbl, 0, sizeof(*log_tbl) + log_size); log_tbl->size = log_size; + log_tbl->final_events_preboot_size = final_events_size; log_tbl->version = version; memcpy(log_tbl->log, (void *) first_entry_addr, log_size); diff --git a/drivers/firmware/efi/tpm.c b/drivers/firmware/efi/tpm.c index 2c912ea08166..0bdceb5913aa 100644 --- a/drivers/firmware/efi/tpm.c +++ b/drivers/firmware/efi/tpm.c @@ -76,7 +76,7 @@ int __init efi_tpm_eventlog_init(void) goto out; } - tbl_size = tpm2_calc_event_log_size(efi.tpm_final_log + tbl_size = tpm2_calc_event_log_size((void *)efi.tpm_final_log + sizeof(final_tbl->version) + sizeof(final_tbl->nr_events), final_tbl->nr_events, diff --git a/include/linux/efi.h b/include/linux/efi.h index e33c70a52a9d..2a26004a9bdb 100644 --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -1703,6 +1703,7 @@ struct linux_efi_random_seed { struct linux_efi_tpm_eventlog { u32 size; + u32 final_events_preboot_size; u8 version; u8 log[]; };
After the first call to GetEventLog() on UEFI systems using the TCG2 crypto agile log format, any further log events (other than those triggered by ExitBootServices()) will be logged in both the main log and also in the Final Events Log. While the kernel only calls GetEventLog() immediately before ExitBootServices(), we can't control whether earlier parts of the boot process have done so. This will result in log entries that exist in both logs, and so the current approach of simply appending the Final Event Log to the main log will result in events being duplicated. We can avoid this problem by looking at the size of the Final Event Log just before we call ExitBootServices() and exporting this to the main kernel. The kernel can then skip over all events that occured before ExitBootServices() and only append events that were not also logged to the main log. Signed-off-by: Matthew Garrett <mjg59@google.com> Reported-by: Joe Richey <joerichey@google.com> Suggested-by: Joe Richey <joerichey@google.com> --- drivers/char/tpm/eventlog/efi.c | 11 ++++++++++- drivers/firmware/efi/libstub/tpm.c | 30 ++++++++++++++++++++++++++++++ drivers/firmware/efi/tpm.c | 2 +- include/linux/efi.h | 1 + 4 files changed, 42 insertions(+), 2 deletions(-)