[Intel-gfx] [PATCH v6 03/10] drm: revocation check at drm subsystem
Singh, Satyeshwar
satyeshwar.singh at intel.com
Tue May 7 12:13:08 UTC 2019
Acked-by: Satyeshwar Singh <satyeshwar.singh at intel.com>
-----Original Message-----
From: Roper, Matthew D
Sent: Monday, May 6, 2019 2:59 PM
To: Daniel Vetter <daniel at ffwll.ch>
Cc: C, Ramalingam <ramalingam.c at intel.com>; Vetter, Daniel <daniel.vetter at intel.com>; intel-gfx at lists.freedesktop.org; dri-devel at lists.freedesktop.org; Singh, Satyeshwar <satyeshwar.singh at intel.com>
Subject: Re: [Intel-gfx] [PATCH v6 03/10] drm: revocation check at drm subsystem
On Mon, May 06, 2019 at 06:56:03PM +0200, Daniel Vetter wrote:
> On Thu, May 02, 2019 at 06:52:56PM +0530, Ramalingam C wrote:
> > On every hdcp revocation check request SRM is read from fw file
> > /lib/firmware/display_hdcp_srm.bin
> >
> > SRM table is parsed and stored at drm_hdcp.c, with functions
> > exported for the services for revocation check from drivers (which
> > implements the HDCP authentication)
> >
> > This patch handles the HDCP1.4 and 2.2 versions of SRM table.
> >
> > v2:
> > moved the uAPI to request_firmware_direct() [Daniel]
> > v3:
> > kdoc added. [Daniel]
> > srm_header unified and bit field definitions are removed. [Daniel]
> > locking improved. [Daniel]
> > vrl length violation is fixed. [Daniel]
> >
> > Signed-off-by: Ramalingam C <ramalingam.c at intel.com>
> > Suggested-by: Daniel Vetter <daniel at ffwll.ch>
>
> Found a few small details to polish, but looks good to me. With the
> details addressed:
>
> Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>
>
> We also still need an ack on the firmware blob approach from Matt
> Roper or someone else at iotg I think.
+Satyeshwar
Satyeshwar's probably the best person from IOTG to give the Ack since he's part of the group that needs this functionality and is involved in the userspace/compositor side as well.
Matt
>
> Cheers, Daniel
>
> > ---
> > Documentation/gpu/drm-kms-helpers.rst | 6 +
> > drivers/gpu/drm/Makefile | 2 +-
> > drivers/gpu/drm/drm_hdcp.c | 342 ++++++++++++++++++++++++++
> > drivers/gpu/drm/drm_internal.h | 4 +
> > drivers/gpu/drm/drm_sysfs.c | 2 +
> > include/drm/drm_hdcp.h | 24 ++
> > 6 files changed, 379 insertions(+), 1 deletion(-) create mode
> > 100644 drivers/gpu/drm/drm_hdcp.c
> >
> > diff --git a/Documentation/gpu/drm-kms-helpers.rst
> > b/Documentation/gpu/drm-kms-helpers.rst
> > index 14102ae035dc..0fe726a6ee67 100644
> > --- a/Documentation/gpu/drm-kms-helpers.rst
> > +++ b/Documentation/gpu/drm-kms-helpers.rst
> > @@ -181,6 +181,12 @@ Panel Helper Reference .. kernel-doc::
> > drivers/gpu/drm/drm_panel_orientation_quirks.c
> > :export:
> >
> > +HDCP Helper Functions Reference
> > +===============================
> > +
> > +.. kernel-doc:: drivers/gpu/drm/drm_hdcp.c
> > + :export:
> > +
> > Display Port Helper Functions Reference
> > =======================================
> >
> > diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
> > index 72f5036d9bfa..dd02e9dec810 100644
> > --- a/drivers/gpu/drm/Makefile
> > +++ b/drivers/gpu/drm/Makefile
> > @@ -17,7 +17,7 @@ drm-y := drm_auth.o drm_cache.o \
> > drm_plane.o drm_color_mgmt.o drm_print.o \
> > drm_dumb_buffers.o drm_mode_config.o drm_vblank.o \
> > drm_syncobj.o drm_lease.o drm_writeback.o drm_client.o \
> > - drm_atomic_uapi.o
> > + drm_atomic_uapi.o drm_hdcp.o
> >
> > drm-$(CONFIG_DRM_LEGACY) += drm_legacy_misc.o drm_bufs.o
> > drm_context.o drm_dma.o drm_scatter.o drm_lock.o
> > drm-$(CONFIG_DRM_LIB_RANDOM) += lib/drm_random.o diff --git
> > a/drivers/gpu/drm/drm_hdcp.c b/drivers/gpu/drm/drm_hdcp.c new file
> > mode 100644 index 000000000000..dc0e13409221
> > --- /dev/null
> > +++ b/drivers/gpu/drm/drm_hdcp.c
> > @@ -0,0 +1,342 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Copyright (C) 2019 Intel Corporation.
> > + *
> > + * Authors:
> > + * Ramalingam C <ramalingam.c at intel.com> */
> > +
> > +#include <linux/device.h>
> > +#include <linux/err.h>
> > +#include <linux/gfp.h>
> > +#include <linux/export.h>
> > +#include <linux/slab.h>
> > +#include <linux/firmware.h>
> > +
> > +#include <drm/drm_hdcp.h>
> > +#include <drm/drm_sysfs.h>
> > +#include <drm/drm_print.h>
> > +#include <drm/drm_device.h>
> > +
> > +struct hdcp_srm {
> > + u8 *srm_buf;
>
> Allocated, but seems to not be used.
>
> > + size_t received_srm_sz;
>
> Seems to be unused. Seems to both be leftovers from the sysfs interface.
>
> > + u32 revoked_ksv_cnt;
> > + u8 *revoked_ksv_list;
> > +
> > + /* Mutex to protect above struct member */
> > + struct mutex mutex;
> > +} *srm_data;
> > +
> > +static inline void drm_hdcp_print_ksv(const u8 *ksv) {
> > + DRM_DEBUG("\t%#02x, %#02x, %#02x, %#02x, %#02x\n",
> > + ksv[0], ksv[1], ksv[2], ksv[3], ksv[4]); }
> > +
> > +static u32 drm_hdcp_get_revoked_ksv_count(const u8 *buf, u32
> > +vrls_length) {
> > + u32 parsed_bytes = 0, ksv_count = 0, vrl_ksv_cnt, vrl_sz;
> > +
> > + while (parsed_bytes < vrls_length) {
> > + vrl_ksv_cnt = *buf;
> > + ksv_count += vrl_ksv_cnt;
> > +
> > + vrl_sz = (vrl_ksv_cnt * DRM_HDCP_KSV_LEN) + 1;
> > + buf += vrl_sz;
> > + parsed_bytes += vrl_sz;
> > + }
> > +
> > + /*
> > + * When vrls are not valid, ksvs are not considered.
> > + * Hence SRM will be discarded.
> > + */
> > + if (parsed_bytes != vrls_length)
> > + ksv_count = 0;
> > +
> > + return ksv_count;
> > +}
> > +
> > +static u32 drm_hdcp_get_revoked_ksvs(const u8 *buf, u8 *revoked_ksv_list,
> > + u32 vrls_length)
> > +{
> > + u32 parsed_bytes = 0, ksv_count = 0;
> > + u32 vrl_ksv_cnt, vrl_ksv_sz, vrl_idx = 0;
> > +
> > + do {
> > + vrl_ksv_cnt = *buf;
> > + vrl_ksv_sz = vrl_ksv_cnt * DRM_HDCP_KSV_LEN;
> > +
> > + buf++;
> > +
> > + DRM_DEBUG("vrl: %d, Revoked KSVs: %d\n", vrl_idx++,
> > + vrl_ksv_cnt);
> > + memcpy(revoked_ksv_list, buf, vrl_ksv_sz);
> > +
> > + ksv_count += vrl_ksv_cnt;
> > + revoked_ksv_list += vrl_ksv_sz;
> > + buf += vrl_ksv_sz;
> > +
> > + parsed_bytes += (vrl_ksv_sz + 1);
> > + } while (parsed_bytes < vrls_length);
> > +
> > + return ksv_count;
> > +}
> > +
> > +static inline u32 get_vrl_length(const u8 *buf) {
> > + return (u32)(buf[0] << 16 | buf[1] << 8 | buf[2]);
>
> This is the same conversion as drm_hdcp2_seq_num_to_u32. Maybe rename
> that to drm_hdcp_be24_bytes_to_cpu and use that instead of what you have hare.
> Plus rename the other function to drm_hdcp_u32_to_b24_bytes for
> consistency. Probably best to do that in a small prep patch.
> > +}
> > +
> > +static int drm_hdcp_parse_hdcp1_srm(const u8 *buf, size_t count) {
> > + struct hdcp_srm_header *header;
> > + u32 vrl_length, ksv_count;
> > +
> > + if (count < (sizeof(struct hdcp_srm_header) +
> > + DRM_HDCP_1_4_VRL_LENGTH_SIZE + DRM_HDCP_1_4_DCP_SIG_SIZE)) {
> > + DRM_ERROR("Invalid blob length\n");
> > + return -EINVAL;
> > + }
> > +
> > + header = (struct hdcp_srm_header *)buf;
> > + DRM_DEBUG("SRM ID: 0x%x, SRM Ver: 0x%x, SRM Gen No: 0x%x\n",
> > + header->srm_id,
> > + __swab16(header->srm_version), header->srm_gen_no);
>
> s/__swab16/be16_to_cpu/ everywhere. Otherwise it'll stop working on
> big endian cpus. Yes won't matter, but better correct, it's also
> better self-documenting code.
>
>
> > +
> > + WARN_ON(header->reserved);
> > +
> > + buf = buf + sizeof(*header);
> > + vrl_length = get_vrl_length(buf);
> > + if (count < (sizeof(struct hdcp_srm_header) + vrl_length) ||
> > + vrl_length < (DRM_HDCP_1_4_VRL_LENGTH_SIZE +
> > + DRM_HDCP_1_4_DCP_SIG_SIZE)) {
> > + DRM_ERROR("Invalid blob length or vrl length\n");
> > + return -EINVAL;
> > + }
> > +
> > + /* Length of the all vrls combined */
> > + vrl_length -= (DRM_HDCP_1_4_VRL_LENGTH_SIZE +
> > + DRM_HDCP_1_4_DCP_SIG_SIZE);
> > +
> > + if (!vrl_length) {
> > + DRM_ERROR("No vrl found\n");
> > + return -EINVAL;
> > + }
> > +
> > + buf += DRM_HDCP_1_4_VRL_LENGTH_SIZE;
> > + ksv_count = drm_hdcp_get_revoked_ksv_count(buf, vrl_length);
> > + if (!ksv_count) {
> > + DRM_DEBUG("Revoked KSV count is 0\n");
> > + return count;
> > + }
> > +
> > + kfree(srm_data->revoked_ksv_list);
> > + srm_data->revoked_ksv_list = kcalloc(ksv_count, DRM_HDCP_KSV_LEN,
> > + GFP_KERNEL);
> > + if (!srm_data->revoked_ksv_list) {
> > + DRM_ERROR("Out of Memory\n");
> > + return -ENOMEM;
> > + }
> > +
> > + if (drm_hdcp_get_revoked_ksvs(buf, srm_data->revoked_ksv_list,
> > + vrl_length) != ksv_count) {
> > + srm_data->revoked_ksv_cnt = 0;
> > + kfree(srm_data->revoked_ksv_list);
> > + return -EINVAL;
> > + }
> > +
> > + srm_data->revoked_ksv_cnt = ksv_count;
> > + return count;
> > +}
> > +
> > +static int drm_hdcp_parse_hdcp2_srm(const u8 *buf, size_t count) {
> > + struct hdcp_srm_header *header;
> > + u32 vrl_length, ksv_count, ksv_sz;
> > +
> > + if (count < (sizeof(struct hdcp_srm_header) +
> > + DRM_HDCP_2_VRL_LENGTH_SIZE + DRM_HDCP_2_DCP_SIG_SIZE)) {
> > + DRM_ERROR("Invalid blob length\n");
> > + return -EINVAL;
> > + }
> > +
> > + header = (struct hdcp_srm_header *)buf;
> > + DRM_DEBUG("SRM ID: 0x%x, SRM Ver: 0x%x, SRM Gen No: 0x%x\n",
> > + header->srm_id & DRM_HDCP_SRM_ID_MASK,
> > + __swab16(header->srm_version), header->srm_gen_no);
> > +
> > + if (header->reserved)
> > + return -EINVAL;
> > +
> > + buf = buf + sizeof(*header);
> > + vrl_length = get_vrl_length(buf);
> > +
> > + if (count < (sizeof(struct hdcp_srm_header) + vrl_length) ||
> > + vrl_length < (DRM_HDCP_2_VRL_LENGTH_SIZE +
> > + DRM_HDCP_2_DCP_SIG_SIZE)) {
> > + DRM_ERROR("Invalid blob length or vrl length\n");
> > + return -EINVAL;
> > + }
> > +
> > + /* Length of the all vrls combined */
> > + vrl_length -= (DRM_HDCP_2_VRL_LENGTH_SIZE +
> > + DRM_HDCP_2_DCP_SIG_SIZE);
> > +
> > + if (!vrl_length) {
> > + DRM_ERROR("No vrl found\n");
> > + return -EINVAL;
> > + }
> > +
> > + buf += DRM_HDCP_2_VRL_LENGTH_SIZE;
> > + ksv_count = (*buf << 2) | DRM_HDCP_2_KSV_COUNT_2_LSBITS(*(buf + 1));
> > + if (!ksv_count) {
> > + DRM_DEBUG("Revoked KSV count is 0\n");
> > + return count;
> > + }
> > +
> > + kfree(srm_data->revoked_ksv_list);
> > + srm_data->revoked_ksv_list = kcalloc(ksv_count, DRM_HDCP_KSV_LEN,
> > + GFP_KERNEL);
> > + if (!srm_data->revoked_ksv_list) {
> > + DRM_ERROR("Out of Memory\n");
> > + return -ENOMEM;
> > + }
> > +
> > + ksv_sz = ksv_count * DRM_HDCP_KSV_LEN;
> > + buf += DRM_HDCP_2_NO_OF_DEV_PLUS_RESERVED_SZ;
> > +
> > + DRM_DEBUG("Revoked KSVs: %d\n", ksv_count);
> > + memcpy(srm_data->revoked_ksv_list, buf, ksv_sz);
> > +
> > + srm_data->revoked_ksv_cnt = ksv_count;
> > + return count;
> > +}
> > +
> > +static inline bool is_srm_version_hdcp1(const u8 *buf) {
> > + return *buf == (u8)(DRM_HDCP_1_4_SRM_ID << 4); }
> > +
> > +static inline bool is_srm_version_hdcp2(const u8 *buf) {
> > + return *buf == (u8)(DRM_HDCP_2_SRM_ID << 4 |
> > +DRM_HDCP_2_INDICATOR); }
> > +
> > +static ssize_t drm_hdcp_srm_update(const u8 *buf, size_t count) {
> > + if (is_srm_version_hdcp1(buf))
> > + return (ssize_t)drm_hdcp_parse_hdcp1_srm(buf, count);
> > + else if (is_srm_version_hdcp2(buf))
> > + return (ssize_t)drm_hdcp_parse_hdcp2_srm(buf, count);
> > +
> > + return (ssize_t)-EINVAL;
>
> You wire return values through but then throw them away. Plus there's
> a confusion between int and ssize_t. Since you have DRM_DEBUG
> everywhere already and we don't care about any parsing errors anyyway
> I think best to throw the return values away and use void for all these functions.
>
> > +}
> > +
> > +void drm_hdcp_request_srm(struct drm_device *drm_dev) {
> > + char fw_name[36] = "display_hdcp_srm.bin";
> > + const struct firmware *fw;
> > +
> > + int ret;
> > +
> > + ret = request_firmware_direct(&fw, (const char *)fw_name,
> > + drm_dev->dev);
> > + if (ret < 0)
> > + goto exit;
> > +
> > + if (fw->size && fw->data)
> > + drm_hdcp_srm_update(fw->data, fw->size);
> > +
> > +exit:
> > + release_firmware(fw);
> > +}
> > +
> > +/**
> > + * drm_hdcp_check_ksvs_revoked - Check the revoked status of the
> > +IDs
> > + *
> > + * @drm_dev: drm_device for which HDCP revocation check is
> > +requested
> > + * @ksvs: List of KSVs (HDCP receiver IDs)
> > + * @ksv_count: KSV count passed in through @ksvs
> > + *
> > + * This function reads the HDCP System renewability Message(SRM
> > +Table)
> > + * from userspace as a firmware and parses it for the revoked HDCP
> > + * KSVs(Receiver IDs) detected by DCP LLC. Once the revoked KSVs
> > +are known,
> > + * revoked state of the KSVs in the list passed in by display
> > +drivers are
> > + * decided and response is sent.
> > + *
> > + * SRM should be presented in the name of "display_hdcp_srm.bin".
> > + *
> > + * Returns:
> > + * TRUE on any of the KSV is revoked, else FALSE.
> > + */
> > +bool drm_hdcp_check_ksvs_revoked(struct drm_device *drm_dev, u8 *ksvs,
> > + u32 ksv_count)
> > +{
> > + u32 rev_ksv_cnt, cnt, i, j;
> > + u8 *rev_ksv_list;
> > +
> > + if (!srm_data)
> > + return false;
> > +
> > + mutex_lock(&srm_data->mutex);
> > + drm_hdcp_request_srm(drm_dev);
> > +
> > + rev_ksv_cnt = srm_data->revoked_ksv_cnt;
> > + rev_ksv_list = srm_data->revoked_ksv_list;
> > +
> > + /* If the Revoked ksv list is empty */
> > + if (!rev_ksv_cnt || !rev_ksv_list) {
> > + mutex_unlock(&srm_data->mutex);
> > + return false;
> > + }
> > +
> > + for (cnt = 0; cnt < ksv_count; cnt++) {
> > + rev_ksv_list = srm_data->revoked_ksv_list;
> > + for (i = 0; i < rev_ksv_cnt; i++) {
> > + for (j = 0; j < DRM_HDCP_KSV_LEN; j++)
> > + if (ksvs[j] != rev_ksv_list[j]) {
> > + break;
> > + } else if (j == (DRM_HDCP_KSV_LEN - 1)) {
> > + DRM_DEBUG("Revoked KSV is ");
> > + drm_hdcp_print_ksv(ksvs);
> > + mutex_unlock(&srm_data->mutex);
> > + return true;
> > + }
> > + /* Move the offset to next KSV in the revoked list */
> > + rev_ksv_list += DRM_HDCP_KSV_LEN;
> > + }
> > +
> > + /* Iterate to next ksv_offset */
> > + ksvs += DRM_HDCP_KSV_LEN;
> > + }
> > + mutex_unlock(&srm_data->mutex);
> > + return false;
> > +}
> > +EXPORT_SYMBOL_GPL(drm_hdcp_check_ksvs_revoked);
> > +
> > +int drm_setup_hdcp_srm(struct class *drm_class) {
> > + srm_data = kzalloc(sizeof(*srm_data), GFP_KERNEL);
> > + if (!srm_data)
> > + return -ENOMEM;
> > +
> > + srm_data->srm_buf = kcalloc(DRM_HDCP_SRM_GEN1_MAX_BYTES,
> > + sizeof(u8), GFP_KERNEL);
> > + if (!srm_data->srm_buf) {
> > + kfree(srm_data);
> > + return -ENOMEM;
> > + }
> > + mutex_init(&srm_data->mutex);
> > +
> > + return 0;
> > +}
> > +
> > +void drm_teardown_hdcp_srm(struct class *drm_class) {
> > + if (srm_data) {
> > + kfree(srm_data->srm_buf);
> > + kfree(srm_data->revoked_ksv_list);
> > + kfree(srm_data);
> > + }
> > +}
> > diff --git a/drivers/gpu/drm/drm_internal.h
> > b/drivers/gpu/drm/drm_internal.h index e19ac7ca602d..476a422414f6
> > 100644
> > --- a/drivers/gpu/drm/drm_internal.h
> > +++ b/drivers/gpu/drm/drm_internal.h
> > @@ -201,3 +201,7 @@ int drm_syncobj_query_ioctl(struct drm_device
> > *dev, void *data, void drm_framebuffer_print_info(struct drm_printer *p, unsigned int indent,
> > const struct drm_framebuffer *fb); int
> > drm_framebuffer_debugfs_init(struct drm_minor *minor);
> > +
> > +/* drm_hdcp.c */
> > +int drm_setup_hdcp_srm(struct class *drm_class); void
> > +drm_teardown_hdcp_srm(struct class *drm_class);
> > diff --git a/drivers/gpu/drm/drm_sysfs.c
> > b/drivers/gpu/drm/drm_sysfs.c index ecb7b33002bb..18b1ac442997
> > 100644
> > --- a/drivers/gpu/drm/drm_sysfs.c
> > +++ b/drivers/gpu/drm/drm_sysfs.c
> > @@ -78,6 +78,7 @@ int drm_sysfs_init(void)
> > }
> >
> > drm_class->devnode = drm_devnode;
> > + drm_setup_hdcp_srm(drm_class);
> > return 0;
> > }
> >
> > @@ -90,6 +91,7 @@ void drm_sysfs_destroy(void) {
> > if (IS_ERR_OR_NULL(drm_class))
> > return;
> > + drm_teardown_hdcp_srm(drm_class);
> > class_remove_file(drm_class, &class_attr_version.attr);
> > class_destroy(drm_class);
> > drm_class = NULL;
> > diff --git a/include/drm/drm_hdcp.h b/include/drm/drm_hdcp.h index
> > f243408ecf26..292998a2497f 100644
> > --- a/include/drm/drm_hdcp.h
> > +++ b/include/drm/drm_hdcp.h
> > @@ -265,4 +265,28 @@ void drm_hdcp2_u32_to_seq_num(u8 seq_num[HDCP_2_2_SEQ_NUM_LEN], u32 val)
> > seq_num[2] = val;
> > }
> >
> > +#define DRM_HDCP_SRM_GEN1_MAX_BYTES (5 * 1024)
> > +#define DRM_HDCP_1_4_SRM_ID 0x8
> > +#define DRM_HDCP_SRM_ID_MASK (0xF << 4)
>
> This is surprising (I'd have expected the hdcp2 indicator in the low
> bits) from reading the spec. But I guess you tested this, and there's
> some mumbo-jumbo about "everything is big endian", which might also
> mean nibbles. Who knows.
>
> > +#define DRM_HDCP_1_4_VRL_LENGTH_SIZE 3
> > +#define DRM_HDCP_1_4_DCP_SIG_SIZE 40
> > +#define DRM_HDCP_2_SRM_ID 0x9
> > +#define DRM_HDCP_2_INDICATOR 0x1
> > +#define DRM_HDCP_2_INDICATOR_MASK 0xF
> > +#define DRM_HDCP_2_VRL_LENGTH_SIZE 3
> > +#define DRM_HDCP_2_DCP_SIG_SIZE 384
> > +#define DRM_HDCP_2_NO_OF_DEV_PLUS_RESERVED_SZ 4
> > +#define DRM_HDCP_2_KSV_COUNT_2_LSBITS(byte) (((byte) & 0xC) >> 6)
> > +
> > +struct hdcp_srm_header {
> > + u8 srm_id;
> > + u8 reserved;
> > + u16 srm_version;
>
> Needs to be __be16, so that sparse can validate you got all the byte
> swapping correct. Would be good to double-check with sparse yourself
> (otherwise 0day will do it for you, but if there's a problem better to
> catch it early).
>
> > + u8 srm_gen_no;
> > +} __packed;
> > +
> > +struct drm_device;
> > +
> > +bool drm_hdcp_check_ksvs_revoked(struct drm_device *dev,
> > + u8 *ksvs, u32 ksv_count);
> > #endif
> > --
> > 2.19.1
> >
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx at lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
>
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx at lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx
--
Matt Roper
Graphics Software Engineer
IoTG Platform Enabling & Development
Intel Corporation
(916) 356-2795
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