Re: [PATCH v5] tpm: Map the ACPI provided event log

Ard Biesheuvel
2024-12-24T16:06:01Z

On Tue, 24 Dec 2024 at 05:03, Jarkko Sakkinen <jarkko@kernel.org> wrote:
>
> The following failure was reported:
>
> [ 10.693310][ T1] tpm_tis STM0925:00: 2.0 TPM (device-id 0x3, rev-id 0)
> [ 10.848132][ T1] ------------[ cut here ]------------
> [ 10.853559][ T1] WARNING: CPU: 59 PID: 1 at mm/page_alloc.c:4727 __alloc_pages_noprof+0x2ca/0x330
> [ 10.862827][ T1] Modules linked in:
> [ 10.866671][ T1] CPU: 59 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.12.0-lp155.2.g52785e2-default #1 openSUSE Tumbleweed (unreleased) 588cd98293a7c9eba9013378d807364c088c9375
> [ 10.882741][ T1] Hardware name: HPE ProLiant DL320 Gen12/ProLiant DL320 Gen12, BIOS 1.20 10/28/2024
> [ 10.892170][ T1] RIP: 0010:__alloc_pages_noprof+0x2ca/0x330
> [ 10.898103][ T1] Code: 24 08 e9 4a fe ff ff e8 34 36 fa ff e9 88 fe ff ff 83 fe 0a 0f 86 b3 fd ff ff 80 3d 01 e7 ce 01 00 75 09 c6 05 f8 e6 ce 01 01 <0f> 0b 45 31 ff e9 e5 fe ff ff f7 c2 00 00 08 00 75 42 89 d9 80 e1
> [ 10.917750][ T1] RSP: 0000:ffffb7cf40077980 EFLAGS: 00010246
> [ 10.923777][ T1] RAX: 0000000000000000 RBX: 0000000000040cc0 RCX: 0000000000000000
> [ 10.931727][ T1] RDX: 0000000000000000 RSI: 000000000000000c RDI: 0000000000040cc0
>
> Above shows that ACPI pointed a 16 MiB buffer for the log events because
> RSI maps to the 'order' parameter of __alloc_pages_noprof(). Address the
> bug by mapping the region when needed instead of copying.
>

How can you be sure the memory contents will be preserved? Does it say
anywhere in the TCG spec that this needs to use a memory type that is
preserved by default?

Also, the fact that we're now at v5 kind of proves my point that this
approach may be too complex for a simple bug fix. Why not switch to
kvmalloc() for a backportable fix, and improve upon that for future
kernels?

> Cc: stable@vger.kernel.org # v2.6.16+
> Fixes: 55a82ab3181b ("[PATCH] tpm: add bios measurement log")
> Reported-by: Andy Liang <andy.liang@hpe.com>
> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=219495
> Suggested-by: Matthew Garrett <mjg59@srcf.ucam.org>
> Tested-by: Andy Liang <andy.liang@hpe.com>
> Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
> ---
> v5:
> * Spotted this right after sending: remove extra acpi_os_unmap_iomem()
> call.
> v4:
> * Added tested-by from Andy Liang.
> v3:
> * Flag mapping code in tpm{1,2}.c with CONFIG_ACPI (nios2 compilation
> fix).
> v2:
> * There was some extra cruft (irrelevant diff), which is now wiped away.
> * Added missing tags (fixes, stable).
> ---
> drivers/char/tpm/eventlog/acpi.c | 27 ++++++---------------
> drivers/char/tpm/eventlog/common.c | 25 +++++++++++++-------
> drivers/char/tpm/eventlog/common.h | 28 ++++++++++++++++++++++
> drivers/char/tpm/eventlog/tpm1.c | 30 ++++++++++++++---------
> drivers/char/tpm/eventlog/tpm2.c | 38 +++++++++++++++++-------------
> include/linux/tpm.h | 1 +
> 6 files changed, 94 insertions(+), 55 deletions(-)
>
> diff --git a/drivers/char/tpm/eventlog/acpi.c b/drivers/char/tpm/eventlog/acpi.c
> index 69533d0bfb51..fb84dd3f6106 100644
> --- a/drivers/char/tpm/eventlog/acpi.c
> +++ b/drivers/char/tpm/eventlog/acpi.c
> @@ -70,14 +70,11 @@ int tpm_read_log_acpi(struct tpm_chip *chip)
> acpi_status status;
> void __iomem *virt;
> u64 len, start;
> - struct tpm_bios_log *log;
> struct acpi_table_tpm2 *tbl;
> struct acpi_tpm2_phy *tpm2_phy;
> int format;
> int ret;
>
> - log = &chip->log;
> -
> /* Unfortuntely ACPI does not associate the event log with a specific
> * TPM, like PPI. Thus all ACPI TPMs will read the same log.
> */
> @@ -135,36 +132,26 @@ int tpm_read_log_acpi(struct tpm_chip *chip)
> return -EIO;
> }
>
> - /* malloc EventLog space */
> - log->bios_event_log = devm_kmalloc(&chip->dev, len, GFP_KERNEL);
> - if (!log->bios_event_log)
> - return -ENOMEM;
> -
> - log->bios_event_log_end = log->bios_event_log + len;
> -
> virt = acpi_os_map_iomem(start, len);
> if (!virt) {
> dev_warn(&chip->dev, "%s: Failed to map ACPI memory\n", __func__);
> /* try EFI log next */
> - ret = -ENODEV;
> - goto err;
> + return -ENODEV;
> }
>
> - memcpy_fromio(log->bios_event_log, virt, len);
> -
> - acpi_os_unmap_iomem(virt, len);
> -
> - if (chip->flags & TPM_CHIP_FLAG_TPM2 &&
> - !tpm_is_tpm2_log(log->bios_event_log, len)) {
> + if (chip->flags & TPM_CHIP_FLAG_TPM2 && !tpm_is_tpm2_log(virt, len)) {
> /* try EFI log next */
> ret = -ENODEV;
> goto err;
> }
>
> + acpi_os_unmap_iomem(virt, len);
> + chip->flags |= TPM_CHIP_FLAG_ACPI_LOG;
> + chip->log.bios_event_log = (void *)start;
> + chip->log.bios_event_log_end = (void *)start + len;
> return format;
>
> err:
> - devm_kfree(&chip->dev, log->bios_event_log);
> - log->bios_event_log = NULL;
> + acpi_os_unmap_iomem(virt, len);
> return ret;
> }
> diff --git a/drivers/char/tpm/eventlog/common.c b/drivers/char/tpm/eventlog/common.c
> index 4c0bbba64ee5..44340ca6e2ac 100644
> --- a/drivers/char/tpm/eventlog/common.c
> +++ b/drivers/char/tpm/eventlog/common.c
> @@ -27,6 +27,7 @@ static int tpm_bios_measurements_open(struct inode *inode,
> {
> int err;
> struct seq_file *seq;
> + struct tpm_measurements *priv;
> struct tpm_chip_seqops *chip_seqops;
> const struct seq_operations *seqops;
> struct tpm_chip *chip;
> @@ -42,13 +43,18 @@ static int tpm_bios_measurements_open(struct inode *inode,
> get_device(&chip->dev);
> inode_unlock(inode);
>
> - /* now register seq file */
> + priv = kzalloc(sizeof(*priv), GFP_KERNEL);
> + if (!priv)
> + return -ENOMEM;
> + priv->chip = chip;
> +
> err = seq_open(file, seqops);
> - if (!err) {
> - seq = file->private_data;
> - seq->private = chip;
> - } else {
> + if (err) {
> + kfree(priv);
> put_device(&chip->dev);
> + } else {
> + seq = file->private_data;
> + seq->private = priv;
> }
>
> return err;
> @@ -58,11 +64,14 @@ static int tpm_bios_measurements_release(struct inode *inode,
> struct file *file)
> {
> struct seq_file *seq = file->private_data;
> - struct tpm_chip *chip = seq->private;
> + struct tpm_measurements *priv = seq->private;
> + int ret;
>
> - put_device(&chip->dev);
> + put_device(&priv->chip->dev);
> + ret = seq_release(inode, file);
> + kfree(priv);
>
> - return seq_release(inode, file);
> + return ret;
> }
>
> static const struct file_operations tpm_bios_measurements_ops = {
> diff --git a/drivers/char/tpm/eventlog/common.h b/drivers/char/tpm/eventlog/common.h
> index 47ff8136ceb5..b98fd6d9a6e9 100644
> --- a/drivers/char/tpm/eventlog/common.h
> +++ b/drivers/char/tpm/eventlog/common.h
> @@ -1,12 +1,40 @@
> #ifndef __TPM_EVENTLOG_COMMON_H__
> #define __TPM_EVENTLOG_COMMON_H__
>
> +#include <linux/acpi.h>
> #include "../tpm.h"
>
> extern const struct seq_operations tpm1_ascii_b_measurements_seqops;
> extern const struct seq_operations tpm1_binary_b_measurements_seqops;
> extern const struct seq_operations tpm2_binary_b_measurements_seqops;
>
> +struct tpm_measurements {
> + struct tpm_chip *chip;
> + void *start;
> + void *end;
> +};
> +
> +static inline bool tpm_measurements_map(struct tpm_measurements *measurements)
> +{
> + struct tpm_chip *chip = measurements->chip;
> + struct tpm_bios_log *log = &chip->log;
> + size_t size;
> +
> + size = log->bios_event_log_end - log->bios_event_log;
> + measurements->start = log->bios_event_log;
> +
> +#ifdef CONFIG_ACPI
> + if (chip->flags & TPM_CHIP_FLAG_ACPI_LOG)
> + measurements->start = acpi_os_map_iomem((unsigned long)log->bios_event_log, size);
> +#endif
> +
> + if (!measurements->start)
> + return false;
> +
> + measurements->end = measurements->start + size;
> + return true;
> +}
> +
> #if defined(CONFIG_ACPI)
> int tpm_read_log_acpi(struct tpm_chip *chip);
> #else
> diff --git a/drivers/char/tpm/eventlog/tpm1.c b/drivers/char/tpm/eventlog/tpm1.c
> index 12ee42a31c71..aef6ee39423a 100644
> --- a/drivers/char/tpm/eventlog/tpm1.c
> +++ b/drivers/char/tpm/eventlog/tpm1.c
> @@ -70,20 +70,23 @@ static const char* tcpa_pc_event_id_strings[] = {
> static void *tpm1_bios_measurements_start(struct seq_file *m, loff_t *pos)
> {
> loff_t i = 0;
> - struct tpm_chip *chip = m->private;
> - struct tpm_bios_log *log = &chip->log;
> - void *addr = log->bios_event_log;
> - void *limit = log->bios_event_log_end;
> + struct tpm_measurements *priv = m->private;
> struct tcpa_event *event;
> u32 converted_event_size;
> u32 converted_event_type;
> + void *addr;
> +
> + if (!tpm_measurements_map(priv))
> + return NULL;
> +
> + addr = priv->start;
>
> /* read over *pos measurements */
> do {
> event = addr;
>
> /* check if current entry is valid */
> - if (addr + sizeof(struct tcpa_event) > limit)
> + if (addr + sizeof(struct tcpa_event) > priv->end)
> return NULL;
>
> converted_event_size =
> @@ -93,7 +96,7 @@ static void *tpm1_bios_measurements_start(struct seq_file *m, loff_t *pos)
>
> if (((converted_event_type == 0) && (converted_event_size == 0))
> || ((addr + sizeof(struct tcpa_event) + converted_event_size)
> - > limit))
> + > priv->end))
> return NULL;
>
> if (i++ == *pos)
> @@ -109,9 +112,7 @@ static void *tpm1_bios_measurements_next(struct seq_file *m, void *v,
> loff_t *pos)
> {
> struct tcpa_event *event = v;
> - struct tpm_chip *chip = m->private;
> - struct tpm_bios_log *log = &chip->log;
> - void *limit = log->bios_event_log_end;
> + struct tpm_measurements *priv = m->private;
> u32 converted_event_size;
> u32 converted_event_type;
>
> @@ -121,7 +122,7 @@ static void *tpm1_bios_measurements_next(struct seq_file *m, void *v,
> v += sizeof(struct tcpa_event) + converted_event_size;
>
> /* now check if current entry is valid */
> - if ((v + sizeof(struct tcpa_event)) > limit)
> + if ((v + sizeof(struct tcpa_event)) > priv->end)
> return NULL;
>
> event = v;
> @@ -130,7 +131,7 @@ static void *tpm1_bios_measurements_next(struct seq_file *m, void *v,
> converted_event_type = do_endian_conversion(event->event_type);
>
> if (((converted_event_type == 0) && (converted_event_size == 0)) ||
> - ((v + sizeof(struct tcpa_event) + converted_event_size) > limit))
> + ((v + sizeof(struct tcpa_event) + converted_event_size) > priv->end))
> return NULL;
>
> return v;
> @@ -138,6 +139,13 @@ static void *tpm1_bios_measurements_next(struct seq_file *m, void *v,
>
> static void tpm1_bios_measurements_stop(struct seq_file *m, void *v)
> {
> +#ifdef CONFIG_ACPI
> + struct tpm_measurements *priv = m->private;
> + struct tpm_chip *chip = priv->chip;
> +
> + if (chip->flags & TPM_CHIP_FLAG_ACPI_LOG)
> + acpi_os_unmap_iomem(priv->start, priv->end - priv->start);
> +#endif
> }
>
> static int get_event_name(char *dest, struct tcpa_event *event,
> diff --git a/drivers/char/tpm/eventlog/tpm2.c b/drivers/char/tpm/eventlog/tpm2.c
> index 37a05800980c..6289d8893e46 100644
> --- a/drivers/char/tpm/eventlog/tpm2.c
> +++ b/drivers/char/tpm/eventlog/tpm2.c
> @@ -41,20 +41,22 @@ static size_t calc_tpm2_event_size(struct tcg_pcr_event2_head *event,
>
> static void *tpm2_bios_measurements_start(struct seq_file *m, loff_t *pos)
> {
> - struct tpm_chip *chip = m->private;
> - struct tpm_bios_log *log = &chip->log;
> - void *addr = log->bios_event_log;
> - void *limit = log->bios_event_log_end;
> + struct tpm_measurements *priv = m->private;
> struct tcg_pcr_event *event_header;
> struct tcg_pcr_event2_head *event;
> size_t size;
> + void *addr;
> int i;
>
> + if (!tpm_measurements_map(priv))
> + return NULL;
> +
> + addr = priv->start;
> event_header = addr;
> size = struct_size(event_header, event, event_header->event_size);
>
> if (*pos == 0) {
> - if (addr + size < limit) {
> + if (addr + size < priv->end) {
> if ((event_header->event_type == 0) &&
> (event_header->event_size == 0))
> return NULL;
> @@ -66,7 +68,7 @@ static void *tpm2_bios_measurements_start(struct seq_file *m, loff_t *pos)
> addr += size;
> event = addr;
> size = calc_tpm2_event_size(event, event_header);
> - if ((addr + size >= limit) || (size == 0))
> + if ((addr + size >= priv->end) || !size)
> return NULL;
> }
>
> @@ -74,7 +76,7 @@ static void *tpm2_bios_measurements_start(struct seq_file *m, loff_t *pos)
> event = addr;
> size = calc_tpm2_event_size(event, event_header);
>
> - if ((addr + size >= limit) || (size == 0))
> + if ((addr + size >= priv->end) || !size)
> return NULL;
> addr += size;
> }
> @@ -87,14 +89,12 @@ static void *tpm2_bios_measurements_next(struct seq_file *m, void *v,
> {
> struct tcg_pcr_event *event_header;
> struct tcg_pcr_event2_head *event;
> - struct tpm_chip *chip = m->private;
> - struct tpm_bios_log *log = &chip->log;
> - void *limit = log->bios_event_log_end;
> + struct tpm_measurements *priv = m->private;
> size_t event_size;
> void *marker;
>
> (*pos)++;
> - event_header = log->bios_event_log;
> + event_header = priv->start;
>
> if (v == SEQ_START_TOKEN) {
> event_size = struct_size(event_header, event,
> @@ -109,13 +109,13 @@ static void *tpm2_bios_measurements_next(struct seq_file *m, void *v,
> }
>
> marker = marker + event_size;
> - if (marker >= limit)
> + if (marker >= priv->end)
> return NULL;
> v = marker;
> event = v;
>
> event_size = calc_tpm2_event_size(event, event_header);
> - if (((v + event_size) >= limit) || (event_size == 0))
> + if (((v + event_size) >= priv->end) || !event_size)
> return NULL;
>
> return v;
> @@ -123,13 +123,19 @@ static void *tpm2_bios_measurements_next(struct seq_file *m, void *v,
>
> static void tpm2_bios_measurements_stop(struct seq_file *m, void *v)
> {
> +#ifdef CONFIG_ACPI
> + struct tpm_measurements *priv = m->private;
> + struct tpm_chip *chip = priv->chip;
> +
> + if (chip->flags & TPM_CHIP_FLAG_ACPI_LOG)
> + acpi_os_unmap_iomem(priv->start, priv->end - priv->start);
> +#endif
> }
>
> static int tpm2_binary_bios_measurements_show(struct seq_file *m, void *v)
> {
> - struct tpm_chip *chip = m->private;
> - struct tpm_bios_log *log = &chip->log;
> - struct tcg_pcr_event *event_header = log->bios_event_log;
> + struct tpm_measurements *priv = m->private;
> + struct tcg_pcr_event *event_header = priv->start;
> struct tcg_pcr_event2_head *event = v;
> void *temp_ptr;
> size_t size;
> diff --git a/include/linux/tpm.h b/include/linux/tpm.h
> index 20a40ade8030..f3d12738b93b 100644
> --- a/include/linux/tpm.h
> +++ b/include/linux/tpm.h
> @@ -348,6 +348,7 @@ enum tpm_chip_flags {
> TPM_CHIP_FLAG_SUSPENDED = BIT(8),
> TPM_CHIP_FLAG_HWRNG_DISABLED = BIT(9),
> TPM_CHIP_FLAG_DISABLE = BIT(10),
> + TPM_CHIP_FLAG_ACPI_LOG = BIT(11),
> };
>
> #define to_tpm_chip(d) container_of(d, struct tpm_chip, dev)
> --
> 2.47.1
>