[PATCH v4 1/6] drm: add DRM_SET_CLIENT_NAME ioctl
Tvrtko Ursulin
tvrtko.ursulin at igalia.com
Mon Sep 30 08:57:04 UTC 2024
On 27/09/2024 09:48, Pierre-Eric Pelloux-Prayer wrote:
> Giving the opportunity to userspace to associate a free-form
> name with a drm_file struct is helpful for tracking and debugging.
>
> This is similar to the existing DMA_BUF_SET_NAME ioctl.
>
> Access to client_name is protected by a mutex, and the 'clients' debugfs
> file has been updated to print it.
>
> Userspace MR to use this ioctl:
> https://gitlab.freedesktop.org/virgl/virglrenderer/-/merge_requests/1428
>
> If the string passed by userspace contains chars that would mess up output
> when it's going to be printed (in dmesg, fdinfo, etc), -EINVAL is returned.
>
> A 0-length string is a valid use, and clears the existing name.
>
> Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin at igalia.com>
> Signed-off-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer at amd.com>
> ---
> drivers/gpu/drm/drm_debugfs.c | 14 ++++++---
> drivers/gpu/drm/drm_file.c | 5 ++++
> drivers/gpu/drm/drm_ioctl.c | 55 +++++++++++++++++++++++++++++++++++
> include/drm/drm_file.h | 9 ++++++
> include/uapi/drm/drm.h | 17 +++++++++++
> 5 files changed, 96 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_debugfs.c b/drivers/gpu/drm/drm_debugfs.c
> index 6b239a24f1df..5c99322a4c6f 100644
> --- a/drivers/gpu/drm/drm_debugfs.c
> +++ b/drivers/gpu/drm/drm_debugfs.c
> @@ -78,12 +78,14 @@ static int drm_clients_info(struct seq_file *m, void *data)
> kuid_t uid;
>
> seq_printf(m,
> - "%20s %5s %3s master a %5s %10s\n",
> + "%20s %5s %3s master a %5s %10s %*s\n",
> "command",
> "tgid",
> "dev",
> "uid",
> - "magic");
> + "magic",
> + DRM_CLIENT_NAME_MAX_LEN,
> + "name");
>
> /* dev->filelist is sorted youngest first, but we want to present
> * oldest first (i.e. kernel, servers, clients), so walk backwardss.
> @@ -94,19 +96,23 @@ static int drm_clients_info(struct seq_file *m, void *data)
> struct task_struct *task;
> struct pid *pid;
>
> + mutex_lock(&priv->client_name_lock);
> rcu_read_lock(); /* Locks priv->pid and pid_task()->comm! */
> pid = rcu_dereference(priv->pid);
> task = pid_task(pid, PIDTYPE_TGID);
> uid = task ? __task_cred(task)->euid : GLOBAL_ROOT_UID;
> - seq_printf(m, "%20s %5d %3d %c %c %5d %10u\n",
> + seq_printf(m, "%20s %5d %3d %c %c %5d %10u %*s\n",
> task ? task->comm : "<unknown>",
> pid_vnr(pid),
> priv->minor->index,
> is_current_master ? 'y' : 'n',
> priv->authenticated ? 'y' : 'n',
> from_kuid_munged(seq_user_ns(m), uid),
> - priv->magic);
> + priv->magic,
> + DRM_CLIENT_NAME_MAX_LEN,
> + priv->client_name ? priv->client_name : "<unset>");
> rcu_read_unlock();
> + mutex_unlock(&priv->client_name_lock);
> }
> mutex_unlock(&dev->filelist_mutex);
> return 0;
> diff --git a/drivers/gpu/drm/drm_file.c b/drivers/gpu/drm/drm_file.c
> index 01fde94fe2a9..64f5e15304e7 100644
> --- a/drivers/gpu/drm/drm_file.c
> +++ b/drivers/gpu/drm/drm_file.c
> @@ -158,6 +158,7 @@ struct drm_file *drm_file_alloc(struct drm_minor *minor)
>
> spin_lock_init(&file->master_lookup_lock);
> mutex_init(&file->event_read_lock);
> + mutex_init(&file->client_name_lock);
>
> if (drm_core_check_feature(dev, DRIVER_GEM))
> drm_gem_open(dev, file);
> @@ -259,6 +260,10 @@ void drm_file_free(struct drm_file *file)
> WARN_ON(!list_empty(&file->event_list));
>
> put_pid(rcu_access_pointer(file->pid));
> +
> + mutex_destroy(&file->client_name_lock);
> + kfree(file->client_name);
> +
> kfree(file);
> }
>
> diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c
> index 51f39912866f..df8d59bd5241 100644
> --- a/drivers/gpu/drm/drm_ioctl.c
> +++ b/drivers/gpu/drm/drm_ioctl.c
> @@ -540,6 +540,59 @@ int drm_version(struct drm_device *dev, void *data,
> return err;
> }
>
> +/*
> + * Check if the passed string contains control char or spaces or
> + * anything that would mess up a formatted output.
> + */
> +static int drm_validate_value_string(const char *value, size_t len)
> +{
> + int i;
> +
> + for (i = 0; i < len; i++) {
> + if (value[i] <= 32 || value[i] >= 127)
Would !isascii() || isgraph() work for what you have in mind here,
considering the comment from the cover letter about the extended ASCII?
> + return -EINVAL;
> + }
> + return 0;
> +}
> +
> +static int drm_set_client_name(struct drm_device *dev, void *data,
> + struct drm_file *file_priv)
> +{
> + struct drm_set_client_name *name = data;
> + void __user *user_ptr;
> + char *new_name;
> + size_t len;
> +
> + if (name->name_len > DRM_CLIENT_NAME_MAX_LEN)
> + return -EINVAL;
> +
> + user_ptr = u64_to_user_ptr(name->name);
> +
> + new_name = memdup_user_nul(user_ptr, name->name_len);
> + if (IS_ERR(new_name))
> + return PTR_ERR(new_name);
> +
> + len = strlen(new_name);
> +
> + if (len != name->name_len ||
> + drm_validate_value_string(new_name, len) < 0) {
> + kfree(new_name);
> + return -EINVAL;
> + }
> +
> + mutex_lock(&file_priv->client_name_lock);
> + kfree(file_priv->client_name);
> + if (len > 0) {
> + file_priv->client_name = new_name;
> + } else {
> + kfree(new_name);
> + file_priv->client_name = NULL;
> + }
> + mutex_unlock(&file_priv->client_name_lock);
FWIW I still find it hard to look at needlessly allocating a string when
userspace has passed name->name_len == 0.
I would have done it something like this:
{
struct drm_set_client_name *name = data;
size_t len = name->len;
char *new_name;
if (len > DRM_CLIENT_NAME_MAX_LEN) {
return -EINVAL;
} else if (len) {
new_name = memdup_user_nul(u64_to_user_ptr(name->name), len);
if (IS_ERR(new_name))
return PTR_ERR(new_name);
if (strlen(new_name) != len ||
drm_validate_value_string(new_name, len) < 0) {
kfree(new_name);
return -EINVAL;
}
} else {
new_name = NULL;
}
mutex_lock(&file_priv->client_name_lock);
kfree(file_priv->client_name);
file_priv->client_name = new_name;
mutex_unlock(&file_priv->client_name_lock);
But whatever, you can keep the r-b regardless.
Regards,
Tvrtko
> +
> + return 0;
> +}
> +
> static int drm_ioctl_permit(u32 flags, struct drm_file *file_priv)
> {
> /* ROOT_ONLY is only for CAP_SYS_ADMIN */
> @@ -610,6 +663,8 @@ static const struct drm_ioctl_desc drm_ioctls[] = {
> DRM_IOCTL_DEF(DRM_IOCTL_PRIME_HANDLE_TO_FD, drm_prime_handle_to_fd_ioctl, DRM_RENDER_ALLOW),
> DRM_IOCTL_DEF(DRM_IOCTL_PRIME_FD_TO_HANDLE, drm_prime_fd_to_handle_ioctl, DRM_RENDER_ALLOW),
>
> + DRM_IOCTL_DEF(DRM_IOCTL_SET_CLIENT_NAME, drm_set_client_name, DRM_RENDER_ALLOW),
> +
> DRM_IOCTL_DEF(DRM_IOCTL_MODE_GETPLANERESOURCES, drm_mode_getplane_res, 0),
> DRM_IOCTL_DEF(DRM_IOCTL_MODE_GETCRTC, drm_mode_getcrtc, 0),
> DRM_IOCTL_DEF(DRM_IOCTL_MODE_SETCRTC, drm_mode_setcrtc, DRM_MASTER),
> diff --git a/include/drm/drm_file.h b/include/drm/drm_file.h
> index 8c0030c77308..d4f1c115ea0f 100644
> --- a/include/drm/drm_file.h
> +++ b/include/drm/drm_file.h
> @@ -388,6 +388,15 @@ struct drm_file {
> * Per-file buffer caches used by the PRIME buffer sharing code.
> */
> struct drm_prime_file_private prime;
> +
> + /**
> + * @client_name:
> + *
> + * Userspace-provided name; useful for accounting and debugging.
> + */
> + const char *client_name;
> + /** @name_lock: Protects @client_name. */
> + struct mutex client_name_lock;
> };
>
> /**
> diff --git a/include/uapi/drm/drm.h b/include/uapi/drm/drm.h
> index 16122819edfe..7fba37b94401 100644
> --- a/include/uapi/drm/drm.h
> +++ b/include/uapi/drm/drm.h
> @@ -1024,6 +1024,13 @@ struct drm_crtc_queue_sequence {
> __u64 user_data; /* user data passed to event */
> };
>
> +#define DRM_CLIENT_NAME_MAX_LEN 64
> +struct drm_set_client_name {
> + __u64 name_len;
> + __u64 name;
> +};
> +
> +
> #if defined(__cplusplus)
> }
> #endif
> @@ -1288,6 +1295,16 @@ extern "C" {
> */
> #define DRM_IOCTL_MODE_CLOSEFB DRM_IOWR(0xD0, struct drm_mode_closefb)
>
> +/**
> + * DRM_IOCTL_SET_CLIENT_NAME - Attach a name to a drm_file
> + *
> + * Having a name allows for easier tracking and debugging.
> + * The length of the name (without null ending char) must be
> + * <= DRM_CLIENT_NAME_MAX_LEN.
> + * The call will fail if the name contains whitespaces or non-printable chars.
> + */
> +#define DRM_IOCTL_SET_CLIENT_NAME DRM_IOWR(0xD1, struct drm_set_client_name)
> +
> /*
> * Device specific ioctls should only be in their respective headers
> * The device specific ioctl range is from 0x40 to 0x9f.
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