| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <9993ad2d-48a8-43be-ae41-4b8d710c1ea7@gmx.de>
Date: Thu, 25 Apr 2024 12:33:28 +0200
From: Helge Deller <deller@....de>
To: Alexey Gladkov <legion@...nel.org>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Jiri Slaby <jirislaby@...nel.org>, LKML <linux-kernel@...r.kernel.org>,
kbd@...ts.linux.dev, linux-api@...r.kernel.org, linux-fbdev@...r.kernel.org,
linux-serial@...r.kernel.org
Subject: Re: [PATCH v5 2/3] VT: Add KDFONTINFO ioctl
On 4/18/24 12:45, Alexey Gladkov wrote:
> On Wed, Apr 17, 2024 at 09:31:53PM +0200, Helge Deller wrote:
>> On 4/17/24 19:37, Alexey Gladkov wrote:
>>> Each driver has its own restrictions on font size. There is currently no
>>> way to understand what the requirements are. The new ioctl allows
>>> userspace to get the minimum and maximum font size values.
>>>
>>> Acked-by: Helge Deller <deller@....de>
>>> Signed-off-by: Alexey Gladkov <legion@...nel.org>
>>> ---
>>> drivers/tty/vt/vt.c | 24 ++++++++++++++++++++++++
>>> drivers/tty/vt/vt_ioctl.c | 13 +++++++++++++
>>> include/linux/console.h | 3 +++
>>> include/linux/vt_kern.h | 1 +
>>> include/uapi/linux/kd.h | 14 ++++++++++++++
>>> 5 files changed, 55 insertions(+)
>>>
>>> diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
>>> index 9b5b98dfc8b4..e8db0e9ea674 100644
>>> --- a/drivers/tty/vt/vt.c
>>> +++ b/drivers/tty/vt/vt.c
>>> @@ -4851,6 +4851,30 @@ int con_font_op(struct vc_data *vc, struct console_font_op *op)
>>> return -ENOSYS;
>>> }
>>>
>>> +int con_font_info(struct vc_data *vc, struct console_font_info *info)
>>> +{
>>> + int rc;
>>> +
>>> + info->min_height = 0;
>>> + info->max_height = max_font_height;
>>> +
>>> + info->min_width = 0;
>>> + info->max_width = max_font_width;
>>> +
>>> + info->flags = KD_FONT_INFO_FLAG_LOW_SIZE | KD_FONT_INFO_FLAG_HIGH_SIZE;
>>> +
>>> + console_lock();
>>> + if (vc->vc_mode != KD_TEXT)
>>> + rc = -EINVAL;
>>> + else if (vc->vc_sw->con_font_info)
>>> + rc = vc->vc_sw->con_font_info(vc, info);
>>> + else
>>> + rc = -ENOSYS;
>>> + console_unlock();
>>> +
>>> + return rc;
>>> +}
>>> +
>>> /*
>>> * Interface exported to selection and vcs.
>>> */
>>> diff --git a/drivers/tty/vt/vt_ioctl.c b/drivers/tty/vt/vt_ioctl.c
>>> index 4b91072f3a4e..9a2f8081f650 100644
>>> --- a/drivers/tty/vt/vt_ioctl.c
>>> +++ b/drivers/tty/vt/vt_ioctl.c
>>> @@ -479,6 +479,19 @@ static int vt_k_ioctl(struct tty_struct *tty, unsigned int cmd,
>>> break;
>>> }
>>>
>>> + case KDFONTINFO: {
>>> + struct console_font_info fnt_info;
>>> +
>>> + memset(&fnt_info, 0, sizeof(fnt_info));
>>> +
>>> + ret = con_font_info(vc, &fnt_info);
>>> + if (ret)
>>> + return ret;
>>> + if (copy_to_user(up, &fnt_info, sizeof(fnt_info)))
>>> + return -EFAULT;
>>> + break;
>>> + }
>>> +
>>> default:
>>> return -ENOIOCTLCMD;
>>> }
>>> diff --git a/include/linux/console.h b/include/linux/console.h
>>> index 31a8f5b85f5d..4b798322aa01 100644
>>> --- a/include/linux/console.h
>>> +++ b/include/linux/console.h
>>> @@ -21,6 +21,7 @@
>>> #include <linux/vesa.h>
>>>
>>> struct vc_data;
>>> +struct console_font_info;
>>> struct console_font_op;
>>> struct console_font;
>>> struct module;
>>> @@ -102,6 +103,8 @@ struct consw {
>>> bool (*con_switch)(struct vc_data *vc);
>>> bool (*con_blank)(struct vc_data *vc, enum vesa_blank_mode blank,
>>> bool mode_switch);
>>> + int (*con_font_info)(struct vc_data *vc,
>>> + struct console_font_info *info);
>>> int (*con_font_set)(struct vc_data *vc,
>>> const struct console_font *font,
>>> unsigned int vpitch, unsigned int flags);
>>> diff --git a/include/linux/vt_kern.h b/include/linux/vt_kern.h
>>> index d008c3d0a9bb..383b3a4f6113 100644
>>> --- a/include/linux/vt_kern.h
>>> +++ b/include/linux/vt_kern.h
>>> @@ -33,6 +33,7 @@ void do_blank_screen(int entering_gfx);
>>> void do_unblank_screen(int leaving_gfx);
>>> void poke_blanked_console(void);
>>> int con_font_op(struct vc_data *vc, struct console_font_op *op);
>>> +int con_font_info(struct vc_data *vc, struct console_font_info *info);
>>> int con_set_cmap(unsigned char __user *cmap);
>>> int con_get_cmap(unsigned char __user *cmap);
>>> void scrollback(struct vc_data *vc);
>>> diff --git a/include/uapi/linux/kd.h b/include/uapi/linux/kd.h
>>> index 8ddb2219a84b..68b715ad4d5c 100644
>>> --- a/include/uapi/linux/kd.h
>>> +++ b/include/uapi/linux/kd.h
>>> @@ -185,6 +185,20 @@ struct console_font {
>>>
>>> #define KD_FONT_FLAG_DONT_RECALC 1 /* Don't recalculate hw charcell size [compat] */
>>>
>>> +/* font information */
>>> +
>>> +#define KD_FONT_INFO_FLAG_LOW_SIZE _BITUL(0) /* 256 */
>>> +#define KD_FONT_INFO_FLAG_HIGH_SIZE _BITUL(1) /* 512 */
>>
>> Do we really need those bits?
>> You set a default min/max font size in con_font_info() above,
>> and all drivers can override those values.
>> So, there are always min/max sizes available.
>
> These bits are not about the minimum and maximum glyph size, but about the
> number of glyphs in the font.
>
> Maybe this is an overkill, but sticon has this check:
>
> if ((w < 6) || (h < 6) || (w > 32) || (h > 32) || (vpitch != 32)
> || (op->charcount != 256 && op->charcount != 512))
>
> [ to be honest, I don’t know why this driver doesn’t accept a glyph of
> width 4 ]
I think there was no technical limitation when I added that.
It's just that the font would be so small...
> I thought it would be worth fixing the maximum number of requirements in
> the drivers since I started adding a new ioctl.
Ok.
Helge
Powered by blists - more mailing lists