[PATCH v1 0/2] Privileged process support on remote subsystem

[PATCH v1 0/2] Privileged process support on remote subsystem

[Ekansh Gupta]

Add support to run remote user process as privileged on remote
subsystem. The privileged user process can be given prioritized
access to remote processor resources. This is achieved in kernel
based on the group ID of the process. The kernel will have a
pre-defined fastrpc group ID and if the process's group ID matches
with it, then the process is treated as a privileged process. This
information is sent to the remote processor during PD initialization
and the PD is treated as a privileged PD.

Ekansh Gupta (2):
  dt-bindings: misc: fastrpc: add fastrpc group IDs property
  misc: fastrpc: detect privileged processes based on group ID

 .../devicetree/bindings/misc/qcom,fastrpc.yaml     |   6 +
 drivers/misc/fastrpc.c                             | 124 +++++++++++++++++++++
 2 files changed, 130 insertions(+)

-- 
2.7.4

[PATCH v1 1/2] dt-bindings: misc: fastrpc: add fastrpc group IDs property

[Ekansh Gupta]

Add "qcom,fastrpc-gids" property to the list of optional properties.
This property contains the list of privileged group IDs which is
used to offload process to remote subsystem with increased privileges.

Signed-off-by: Ekansh Gupta <quic_ekangupt@quicinc.com>
---
 Documentation/devicetree/bindings/misc/qcom,fastrpc.yaml | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/devicetree/bindings/misc/qcom,fastrpc.yaml b/Documentation/devicetree/bindings/misc/qcom,fastrpc.yaml
index 1ab9588..2a2124f 100644
--- a/Documentation/devicetree/bindings/misc/qcom,fastrpc.yaml
+++ b/Documentation/devicetree/bindings/misc/qcom,fastrpc.yaml
@@ -57,6 +57,11 @@ properties:
       Virtual machine IDs for remote processor.
     $ref: "/schemas/types.yaml#/definitions/uint32-array"
 
+  qcom,fastrpc-gids:
+    description:
+      Group IDs for fastrpc.
+    $ref: "/schemas/types.yaml#/definitions/uint32-array"
+
   "#address-cells":
     const: 1
 
@@ -120,6 +125,7 @@ examples:
             qcom,glink-channels = "fastrpcglink-apps-dsp";
             label = "sdsp";
             qcom,non-secure-domain;
+            qcom,fastrpc-gids = <2908>
             #address-cells = <1>;
             #size-cells = <0>;
 
-- 
2.7.4

Re: [PATCH v1 1/2] dt-bindings: misc: fastrpc: add fastrpc group IDs property

[Krzysztof Kozlowski]

On 07/06/2023 13:54, Ekansh Gupta wrote:
> Add "qcom,fastrpc-gids" property to the list of optional properties.
> This property contains the list of privileged group IDs which is
> used to offload process to remote subsystem with increased privileges.
> 
> Signed-off-by: Ekansh Gupta <quic_ekangupt@quicinc.com>

Please use scripts/get_maintainers.pl to get a list of necessary people
and lists to CC.  It might happen, that command when run on an older
kernel, gives you outdated entries.  Therefore please be sure you base
your patches on recent Linux kernel.

You missed at least DT list (maybe more), so this won't be tested.
Please resend and include all necessary entries.

Best regards,
Krzysztof

[PATCH v1 2/2] misc: fastrpc: detect privileged processes based on group ID

[Ekansh Gupta]

Get the information on privileged group IDs during rpmsg probing based
on DT property. Check if the process requesting an offload to remote
subsystem is privileged by comparing it's group ID with privileged
group ID. Initialization process attributes are updated for a
privileged process which is sent to remote process for resource
management.

Signed-off-by: Ekansh Gupta <quic_ekangupt@quicinc.com>
---
 drivers/misc/fastrpc.c | 124 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 124 insertions(+)

diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
index 30d4d04..6c7db0b 100644
--- a/drivers/misc/fastrpc.c
+++ b/drivers/misc/fastrpc.c
@@ -21,6 +21,7 @@
 #include <linux/firmware/qcom/qcom_scm.h>
 #include <uapi/misc/fastrpc.h>
 #include <linux/of_reserved_mem.h>
+#include <linux/cred.h>
 
 #define ADSP_DOMAIN_ID (0)
 #define MDSP_DOMAIN_ID (1)
@@ -166,6 +167,11 @@ struct fastrpc_mem_unmap_req_msg {
 	u64 len;
 };
 
+struct gid_list {
+	u32 *gids;
+	u32 gidcount;
+};
+
 struct fastrpc_msg {
 	int pid;		/* process group id */
 	int tid;		/* thread id */
@@ -277,6 +283,7 @@ struct fastrpc_channel_ctx {
 	struct fastrpc_device *fdevice;
 	struct fastrpc_buf *remote_heap;
 	struct list_head invoke_interrupted_mmaps;
+	struct gid_list gidlist;
 	bool secure;
 	bool unsigned_support;
 	u64 dma_mask;
@@ -305,6 +312,7 @@ struct fastrpc_user {
 	spinlock_t lock;
 	/* lock for allocations */
 	struct mutex mutex;
+	struct gid_list gidlist;
 };
 
 static void fastrpc_free_map(struct kref *ref)
@@ -522,6 +530,31 @@ static void fastrpc_context_put_wq(struct work_struct *work)
 }
 
 #define CMP(aa, bb) ((aa) == (bb) ? 0 : (aa) < (bb) ? -1 : 1)
+
+static u32 sorted_lists_intersection(u32 *listA,
+		u32 lenA, u32 *listB, u32 lenB)
+{
+	u32 i = 0, j = 0;
+
+	while (i < lenA && j < lenB) {
+		if (listA[i] < listB[j])
+			i++;
+		else if (listA[i] > listB[j])
+			j++;
+		else
+			return listA[i];
+	}
+	return 0;
+}
+
+static int uint_cmp_func(const void *p1, const void *p2)
+{
+	u32 a1 = *((u32 *)p1);
+	u32 a2 = *((u32 *)p2);
+
+	return CMP(a1, a2);
+}
+
 static int olaps_cmp(const void *a, const void *b)
 {
 	struct fastrpc_buf_overlap *pa = (struct fastrpc_buf_overlap *)a;
@@ -1230,6 +1263,50 @@ static bool is_session_rejected(struct fastrpc_user *fl, bool unsigned_pd_reques
 	return false;
 }
 
+static int fastrpc_get_process_gids(struct gid_list *gidlist)
+{
+	struct group_info *group_info = get_current_groups();
+	int i, num_gids;
+	u32 *gids = NULL;
+
+	if (!group_info)
+		return -EFAULT;
+
+	num_gids = group_info->ngroups + 1;
+	gids = kcalloc(num_gids, sizeof(u32), GFP_KERNEL);
+	if (!gids)
+		return -ENOMEM;
+
+	/* Get the real GID */
+	gids[0] = __kgid_val(current_gid());
+
+	/* Get the supplemental GIDs */
+	for (i = 1; i < num_gids; i++)
+		gids[i] = __kgid_val(group_info->gid[i - 1]);
+
+	sort(gids, num_gids, sizeof(*gids), uint_cmp_func, NULL);
+	gidlist->gids = gids;
+	gidlist->gidcount = num_gids;
+
+	return 0;
+}
+
+static void fastrpc_check_privileged_process(struct fastrpc_user *fl,
+				struct fastrpc_init_create *init)
+{
+	u32 gid = sorted_lists_intersection(fl->gidlist.gids,
+			fl->gidlist.gidcount, fl->cctx->gidlist.gids,
+			fl->cctx->gidlist.gidcount);
+
+	/* disregard any privilege bits from userspace */
+	init->attrs &= (~FASTRPC_MODE_PRIVILEGED);
+	if (gid) {
+		dev_info(&fl->cctx->rpdev->dev, "%s: %s (PID %d, GID %u) is a privileged process\n",
+				__func__, current->comm, fl->tgid, gid);
+		init->attrs |= FASTRPC_MODE_PRIVILEGED;
+	}
+}
+
 static int fastrpc_init_create_static_process(struct fastrpc_user *fl,
 					      char __user *argp)
 {
@@ -1386,6 +1463,8 @@ static int fastrpc_init_create_process(struct fastrpc_user *fl,
 		goto err;
 	}
 
+	fastrpc_get_process_gids(&fl->gidlist);
+
 	inbuf.pgid = fl->tgid;
 	inbuf.namelen = strlen(current->comm) + 1;
 	inbuf.filelen = init.filelen;
@@ -1400,6 +1479,8 @@ static int fastrpc_init_create_process(struct fastrpc_user *fl,
 			goto err;
 	}
 
+	fastrpc_check_privileged_process(fl, &init);
+
 	memlen = ALIGN(max(INIT_FILELEN_MAX, (int)init.filelen * 4),
 		       1024 * 1024);
 	err = fastrpc_buf_alloc(fl, fl->sctx->dev, memlen,
@@ -1519,6 +1600,7 @@ static int fastrpc_device_release(struct inode *inode, struct file *file)
 	spin_lock_irqsave(&cctx->lock, flags);
 	list_del(&fl->user);
 	spin_unlock_irqrestore(&cctx->lock, flags);
+	kfree(fl->gidlist.gids);
 
 	if (fl->init_mem)
 		fastrpc_buf_free(fl->init_mem);
@@ -2118,6 +2200,43 @@ static long fastrpc_device_ioctl(struct file *file, unsigned int cmd,
 	return err;
 }
 
+static int fastrpc_init_privileged_gids(struct device *dev, char *prop_name,
+						struct gid_list *gidlist)
+{
+	int err = 0;
+	u32 len = 0, i;
+	u32 *gids = NULL;
+
+	if (!of_find_property(dev->of_node, prop_name, &len))
+		return 0;
+	if (len == 0)
+		return 0;
+
+	len /= sizeof(u32);
+	gids = kcalloc(len, sizeof(u32), GFP_KERNEL);
+	if (!gids)
+		return -ENOMEM;
+
+	for (i = 0; i < len; i++) {
+		err = of_property_read_u32_index(dev->of_node, prop_name,
+								i, &gids[i]);
+		if (err) {
+			dev_err(dev, "%s: failed to read GID %u\n",
+					__func__, i);
+			goto read_error;
+		}
+		dev_info(dev, "adsprpc: %s: privileged GID: %u\n", __func__, gids[i]);
+	}
+	sort(gids, len, sizeof(*gids), uint_cmp_func, NULL);
+	gidlist->gids = gids;
+	gidlist->gidcount = len;
+
+	return 0;
+read_error:
+	kfree(gids);
+	return err;
+}
+
 static const struct file_operations fastrpc_fops = {
 	.open = fastrpc_device_open,
 	.release = fastrpc_device_release,
@@ -2277,6 +2396,10 @@ static int fastrpc_rpmsg_probe(struct rpmsg_device *rpdev)
 	if (!data)
 		return -ENOMEM;
 
+	err = fastrpc_init_privileged_gids(rdev, "qcom,fastrpc-gids", &data->gidlist);
+	if (err)
+		dev_err(rdev, "Privileged gids init failed.\n");
+
 	if (vmcount) {
 		data->vmcount = vmcount;
 		data->perms = BIT(QCOM_SCM_VMID_HLOS);
@@ -2382,6 +2505,7 @@ static void fastrpc_rpmsg_remove(struct rpmsg_device *rpdev)
 	if (cctx->remote_heap)
 		fastrpc_buf_free(cctx->remote_heap);
 
+	kfree(cctx->gidlist.gids);
 	of_platform_depopulate(&rpdev->dev);
 
 	fastrpc_channel_ctx_put(cctx);
-- 
2.7.4

Re: [PATCH v1 2/2] misc: fastrpc: detect privileged processes based on group ID

[Srinivas Kandagatla]

Hi Ekansh,
thankyou for your email.

On 07/06/2023 12:54, Ekansh Gupta wrote:
> Get the information on privileged group IDs during rpmsg probing based
> on DT property. Check if the process requesting an offload to remote
> subsystem is privileged by comparing it's group ID with privileged

policy management should be dealt in the user-space not in the kernel.

The patch is not correct approach!

In this particular case the fastrpc library can take the right call 
based on the group id of the process along with system policy and set 
attr with correct flags while sending a invoke request.

--srini

> group ID. Initialization process attributes are updated for a
> privileged process which is sent to remote process for resource
> management.
> 
> Signed-off-by: Ekansh Gupta <quic_ekangupt@quicinc.com>
> ---
>   drivers/misc/fastrpc.c | 124 +++++++++++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 124 insertions(+)
> 
> diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
> index 30d4d04..6c7db0b 100644
> --- a/drivers/misc/fastrpc.c
> +++ b/drivers/misc/fastrpc.c
> @@ -21,6 +21,7 @@
>   #include <linux/firmware/qcom/qcom_scm.h>
>   #include <uapi/misc/fastrpc.h>
>   #include <linux/of_reserved_mem.h>
> +#include <linux/cred.h>
>   
>   #define ADSP_DOMAIN_ID (0)
>   #define MDSP_DOMAIN_ID (1)
> @@ -166,6 +167,11 @@ struct fastrpc_mem_unmap_req_msg {
>   	u64 len;
>   };
>   
> +struct gid_list {
> +	u32 *gids;
> +	u32 gidcount;
> +};
> +
>   struct fastrpc_msg {
>   	int pid;		/* process group id */
>   	int tid;		/* thread id */
> @@ -277,6 +283,7 @@ struct fastrpc_channel_ctx {
>   	struct fastrpc_device *fdevice;
>   	struct fastrpc_buf *remote_heap;
>   	struct list_head invoke_interrupted_mmaps;
> +	struct gid_list gidlist;
>   	bool secure;
>   	bool unsigned_support;
>   	u64 dma_mask;
> @@ -305,6 +312,7 @@ struct fastrpc_user {
>   	spinlock_t lock;
>   	/* lock for allocations */
>   	struct mutex mutex;
> +	struct gid_list gidlist;
>   };
>   
>   static void fastrpc_free_map(struct kref *ref)
> @@ -522,6 +530,31 @@ static void fastrpc_context_put_wq(struct work_struct *work)
>   }
>   
>   #define CMP(aa, bb) ((aa) == (bb) ? 0 : (aa) < (bb) ? -1 : 1)
> +
> +static u32 sorted_lists_intersection(u32 *listA,
> +		u32 lenA, u32 *listB, u32 lenB)
> +{
> +	u32 i = 0, j = 0;
> +
> +	while (i < lenA && j < lenB) {
> +		if (listA[i] < listB[j])
> +			i++;
> +		else if (listA[i] > listB[j])
> +			j++;
> +		else
> +			return listA[i];
> +	}
> +	return 0;
> +}
> +
> +static int uint_cmp_func(const void *p1, const void *p2)
> +{
> +	u32 a1 = *((u32 *)p1);
> +	u32 a2 = *((u32 *)p2);
> +
> +	return CMP(a1, a2);
> +}
> +
>   static int olaps_cmp(const void *a, const void *b)
>   {
>   	struct fastrpc_buf_overlap *pa = (struct fastrpc_buf_overlap *)a;
> @@ -1230,6 +1263,50 @@ static bool is_session_rejected(struct fastrpc_user *fl, bool unsigned_pd_reques
>   	return false;
>   }
>   
> +static int fastrpc_get_process_gids(struct gid_list *gidlist)
> +{
> +	struct group_info *group_info = get_current_groups();
> +	int i, num_gids;
> +	u32 *gids = NULL;
> +
> +	if (!group_info)
> +		return -EFAULT;
> +
> +	num_gids = group_info->ngroups + 1;
> +	gids = kcalloc(num_gids, sizeof(u32), GFP_KERNEL);
> +	if (!gids)
> +		return -ENOMEM;
> +
> +	/* Get the real GID */
> +	gids[0] = __kgid_val(current_gid());
> +
> +	/* Get the supplemental GIDs */
> +	for (i = 1; i < num_gids; i++)
> +		gids[i] = __kgid_val(group_info->gid[i - 1]);
> +
> +	sort(gids, num_gids, sizeof(*gids), uint_cmp_func, NULL);
> +	gidlist->gids = gids;
> +	gidlist->gidcount = num_gids;
> +
> +	return 0;
> +}
> +
> +static void fastrpc_check_privileged_process(struct fastrpc_user *fl,
> +				struct fastrpc_init_create *init)
> +{
> +	u32 gid = sorted_lists_intersection(fl->gidlist.gids,
> +			fl->gidlist.gidcount, fl->cctx->gidlist.gids,
> +			fl->cctx->gidlist.gidcount);
> +
> +	/* disregard any privilege bits from userspace */
> +	init->attrs &= (~FASTRPC_MODE_PRIVILEGED);
> +	if (gid) {
> +		dev_info(&fl->cctx->rpdev->dev, "%s: %s (PID %d, GID %u) is a privileged process\n",
> +				__func__, current->comm, fl->tgid, gid);
> +		init->attrs |= FASTRPC_MODE_PRIVILEGED;
> +	}
> +}
> +
>   static int fastrpc_init_create_static_process(struct fastrpc_user *fl,
>   					      char __user *argp)
>   {
> @@ -1386,6 +1463,8 @@ static int fastrpc_init_create_process(struct fastrpc_user *fl,
>   		goto err;
>   	}
>   
> +	fastrpc_get_process_gids(&fl->gidlist);
> +
>   	inbuf.pgid = fl->tgid;
>   	inbuf.namelen = strlen(current->comm) + 1;
>   	inbuf.filelen = init.filelen;
> @@ -1400,6 +1479,8 @@ static int fastrpc_init_create_process(struct fastrpc_user *fl,
>   			goto err;
>   	}
>   
> +	fastrpc_check_privileged_process(fl, &init);
> +
>   	memlen = ALIGN(max(INIT_FILELEN_MAX, (int)init.filelen * 4),
>   		       1024 * 1024);
>   	err = fastrpc_buf_alloc(fl, fl->sctx->dev, memlen,
> @@ -1519,6 +1600,7 @@ static int fastrpc_device_release(struct inode *inode, struct file *file)
>   	spin_lock_irqsave(&cctx->lock, flags);
>   	list_del(&fl->user);
>   	spin_unlock_irqrestore(&cctx->lock, flags);
> +	kfree(fl->gidlist.gids);
>   
>   	if (fl->init_mem)
>   		fastrpc_buf_free(fl->init_mem);
> @@ -2118,6 +2200,43 @@ static long fastrpc_device_ioctl(struct file *file, unsigned int cmd,
>   	return err;
>   }
>   
> +static int fastrpc_init_privileged_gids(struct device *dev, char *prop_name,
> +						struct gid_list *gidlist)
> +{
> +	int err = 0;
> +	u32 len = 0, i;
> +	u32 *gids = NULL;
> +
> +	if (!of_find_property(dev->of_node, prop_name, &len))
> +		return 0;
> +	if (len == 0)
> +		return 0;
> +
> +	len /= sizeof(u32);
> +	gids = kcalloc(len, sizeof(u32), GFP_KERNEL);
> +	if (!gids)
> +		return -ENOMEM;
> +
> +	for (i = 0; i < len; i++) {
> +		err = of_property_read_u32_index(dev->of_node, prop_name,
> +								i, &gids[i]);
> +		if (err) {
> +			dev_err(dev, "%s: failed to read GID %u\n",
> +					__func__, i);
> +			goto read_error;
> +		}
> +		dev_info(dev, "adsprpc: %s: privileged GID: %u\n", __func__, gids[i]);
> +	}
> +	sort(gids, len, sizeof(*gids), uint_cmp_func, NULL);
> +	gidlist->gids = gids;
> +	gidlist->gidcount = len;
> +
> +	return 0;
> +read_error:
> +	kfree(gids);
> +	return err;
> +}
> +
>   static const struct file_operations fastrpc_fops = {
>   	.open = fastrpc_device_open,
>   	.release = fastrpc_device_release,
> @@ -2277,6 +2396,10 @@ static int fastrpc_rpmsg_probe(struct rpmsg_device *rpdev)
>   	if (!data)
>   		return -ENOMEM;
>   
> +	err = fastrpc_init_privileged_gids(rdev, "qcom,fastrpc-gids", &data->gidlist);
> +	if (err)
> +		dev_err(rdev, "Privileged gids init failed.\n");
> +
>   	if (vmcount) {
>   		data->vmcount = vmcount;
>   		data->perms = BIT(QCOM_SCM_VMID_HLOS);
> @@ -2382,6 +2505,7 @@ static void fastrpc_rpmsg_remove(struct rpmsg_device *rpdev)
>   	if (cctx->remote_heap)
>   		fastrpc_buf_free(cctx->remote_heap);
>   
> +	kfree(cctx->gidlist.gids);
>   	of_platform_depopulate(&rpdev->dev);
>   
>   	fastrpc_channel_ctx_put(cctx);