| Message ID | 20230612141352.29939-1-tzimmermann@suse.de (mailing list archive) |
|---|---|
| Headers | show |
| Series | fbdev: Make userspace interfaces optional | expand |
Hi Thomas, Nice series, quite some preparations. On Mon, Jun 12, 2023 at 04:07:38PM +0200, Thomas Zimmermann wrote: > Add the new config option FB_DEVICE. If enabled, fbdev provides > traditional userspace interfaces in devfs, sysfs and procfs, such > as /dev/fb0 or /proc/fb. > > Modern Linux distrobutions have adopted DRM drivers for graphics > output and use fbdev only for the kernel's framebuffer console. > Userspace has also moved on, with no new fbdev code being written > and existing support being removed. > > OTOH, fbdev provides userspace a way of accessing kernel or I/O > memory, which might compromise the system's security. See the recent > commit c8687694bb1f ("drm/fbdev-generic: prohibit potential > out-of-bounds access") for an example. Disabling fbdev userspace > interfaces is therefore a useful feature to limit unnecessary > exposure of fbdev code to processes of low privilegues. > > Patches 1 to 31 fix various bugs and issues in fbdev-related code. > In most cases the code uses the fbdev device where it should use > the Linux hardware device or something else. Most of these patches > fix existing problems and should therefore be considered in any case. > > Patches 32 to 37 refactor the fbdev core code. The patches move > support for backlights, sysfs, procfs and devfs into separate files > and hide it behind simple interfaces. These changes will allow to > easily build the userspace support conditionally. > > Patch 38 introduces the config option FB_DEVICE and adapts the fbdev > core to support it. The field struct fb_info.dev is now optional, > hence the name of the config option. > > Tested on simpledrm and i915, including the device handover. > > Future directions: With the support for disabling fbdev userspace > interfaces in place, it will be possible to make most fbdev drivers' > file-I/O code in struct fb_ops optional as well. > > v2: > * fix fsl-diu-fb and sh7760fb > * split backlight patches > * set 'default y' for FB_CONFIG > * minor fixes and corrections > > Thomas Zimmermann (38): > backlight/bd6107: Compare against struct fb_info.device > backlight/bd6107: Rename struct bd6107_platform_data.fbdev to 'dev' > backlight/gpio_backlight: Compare against struct fb_info.device > backlight/gpio_backlight: Rename field 'fbdev' to 'dev' > backlight/lv5207lp: Compare against struct fb_info.device > backlight/lv5207lp: Rename struct lv5207lp_platform_data.fbdev to > 'dev' > fbdev/atyfb: Reorder backlight and framebuffer init/cleanup > fbdev/atyfb: Use hardware device as backlight parent > fbdev/aty128fb: Reorder backlight and framebuffer init/cleanup > fbdev/aty128fb: Use hardware device as backlight parent > fbdev/broadsheetfb: Call device_remove_file() with hardware device > fbdev/ep93xx-fb: Output messages with fb_info() and fb_err() > fbdev/ep93xx-fb: Do not assign to struct fb_info.dev > fbdev/fsl-diu-fb: Output messages with fb_*() helpers > fbdev/mb862xxfb: Output messages with fb_dbg() > fbdev/metronomefb: Use hardware device for dev_err() > fbdev/nvidiafb: Reorder backlight and framebuffer init/cleanup > fbdev/nvidiafb: Use hardware device as backlight parent > fbdev/pxa168fb: Do not assign to struct fb_info.dev > fbdev/radeonfb: Reorder backlight and framebuffer cleanup > fbdev/radeonfb: Use hardware device as backlight parent > fbdev/rivafb: Reorder backlight and framebuffer init/cleanup > fbdev/rivafb: Use hardware device as backlight parent > fbdev/sh7760fb: Use fb_dbg() in sh7760fb_get_color_info() > fbdev/sh7760fb: Output messages with fb_dbg() > fbdev/sh7760fb: Use hardware device with dev_() output during probe > fbdev/sm501fb: Output message with fb_err() > fbdev/tdfxfb: Set i2c adapter parent to hardware device The above are all: Reviewed-by: Sam Ravnborg <sam@ravnborg.org> > fbdev/smscufx: Detect registered fb_info from refcount I did not try to understand the code, so others must review. > fbdev/ep93xx-fb: Alloc DMA memory from hardware device > fbdev/sh7760fb: Alloc DMA memory from hardware device This smells like bug-fixes, and I do not see what impact the change has. So again, someone else needs to provide review here. The rest are already reviewed or got a dedicated reply. Sam
Sam Ravnborg <sam@ravnborg.org> writes: Hello Sam, > Hi Thomas, > > Nice series, quite some preparations. > > On Mon, Jun 12, 2023 at 04:07:38PM +0200, Thomas Zimmermann wrote: [...] >> fbdev/smscufx: Detect registered fb_info from refcount > I did not try to understand the code, so others must review. > No worries, I already reviewed that one. >> fbdev/ep93xx-fb: Alloc DMA memory from hardware device >> fbdev/sh7760fb: Alloc DMA memory from hardware device > This smells like bug-fixes, and I do not see what impact the change has. > So again, someone else needs to provide review here. > And same for these.
Hi Sam and Javier Am 12.06.23 um 18:04 schrieb Javier Martinez Canillas: > Sam Ravnborg <sam@ravnborg.org> writes: > > Hello Sam, > >> Hi Thomas, >> >> Nice series, quite some preparations. >> >> On Mon, Jun 12, 2023 at 04:07:38PM +0200, Thomas Zimmermann wrote: > > [...] > >>> fbdev/smscufx: Detect registered fb_info from refcount >> I did not try to understand the code, so others must review. >> > > No worries, I already reviewed that one. > >>> fbdev/ep93xx-fb: Alloc DMA memory from hardware device >>> fbdev/sh7760fb: Alloc DMA memory from hardware device >> This smells like bug-fixes, and I do not see what impact the change has. >> So again, someone else needs to provide review here. >> > > And same for these. > Thanks to both of you for reviewing the patches. Best regards Thomas
Add the new config option FB_DEVICE. If enabled, fbdev provides traditional userspace interfaces in devfs, sysfs and procfs, such as /dev/fb0 or /proc/fb. Modern Linux distrobutions have adopted DRM drivers for graphics output and use fbdev only for the kernel's framebuffer console. Userspace has also moved on, with no new fbdev code being written and existing support being removed. OTOH, fbdev provides userspace a way of accessing kernel or I/O memory, which might compromise the system's security. See the recent commit c8687694bb1f ("drm/fbdev-generic: prohibit potential out-of-bounds access") for an example. Disabling fbdev userspace interfaces is therefore a useful feature to limit unnecessary exposure of fbdev code to processes of low privilegues. Patches 1 to 31 fix various bugs and issues in fbdev-related code. In most cases the code uses the fbdev device where it should use the Linux hardware device or something else. Most of these patches fix existing problems and should therefore be considered in any case. Patches 32 to 37 refactor the fbdev core code. The patches move support for backlights, sysfs, procfs and devfs into separate files and hide it behind simple interfaces. These changes will allow to easily build the userspace support conditionally. Patch 38 introduces the config option FB_DEVICE and adapts the fbdev core to support it. The field struct fb_info.dev is now optional, hence the name of the config option. Tested on simpledrm and i915, including the device handover. Future directions: With the support for disabling fbdev userspace interfaces in place, it will be possible to make most fbdev drivers' file-I/O code in struct fb_ops optional as well. v2: * fix fsl-diu-fb and sh7760fb * split backlight patches * set 'default y' for FB_CONFIG * minor fixes and corrections Thomas Zimmermann (38): backlight/bd6107: Compare against struct fb_info.device backlight/bd6107: Rename struct bd6107_platform_data.fbdev to 'dev' backlight/gpio_backlight: Compare against struct fb_info.device backlight/gpio_backlight: Rename field 'fbdev' to 'dev' backlight/lv5207lp: Compare against struct fb_info.device backlight/lv5207lp: Rename struct lv5207lp_platform_data.fbdev to 'dev' fbdev/atyfb: Reorder backlight and framebuffer init/cleanup fbdev/atyfb: Use hardware device as backlight parent fbdev/aty128fb: Reorder backlight and framebuffer init/cleanup fbdev/aty128fb: Use hardware device as backlight parent fbdev/broadsheetfb: Call device_remove_file() with hardware device fbdev/ep93xx-fb: Alloc DMA memory from hardware device fbdev/ep93xx-fb: Output messages with fb_info() and fb_err() fbdev/ep93xx-fb: Do not assign to struct fb_info.dev fbdev/fsl-diu-fb: Output messages with fb_*() helpers fbdev/mb862xxfb: Output messages with fb_dbg() fbdev/metronomefb: Use hardware device for dev_err() fbdev/nvidiafb: Reorder backlight and framebuffer init/cleanup fbdev/nvidiafb: Use hardware device as backlight parent fbdev/pxa168fb: Do not assign to struct fb_info.dev fbdev/radeonfb: Reorder backlight and framebuffer cleanup fbdev/radeonfb: Use hardware device as backlight parent fbdev/rivafb: Reorder backlight and framebuffer init/cleanup fbdev/rivafb: Use hardware device as backlight parent fbdev/sh7760fb: Use fb_dbg() in sh7760fb_get_color_info() fbdev/sh7760fb: Output messages with fb_dbg() fbdev/sh7760fb: Alloc DMA memory from hardware device fbdev/sh7760fb: Use hardware device with dev_() output during probe fbdev/sm501fb: Output message with fb_err() fbdev/smscufx: Detect registered fb_info from refcount fbdev/tdfxfb: Set i2c adapter parent to hardware device fbdev/core: Pass Linux device to pm_vt_switch_*() functions fbdev/core: Move framebuffer and backlight helpers into separate files fbdev/core: Add fb_device_{create,destroy}() fbdev/core: Move procfs code to separate file fbdev/core: Move file-I/O code into separate file fbdev/core: Rework fb init code fbdev: Make support for userspace interfaces configurable Documentation/gpu/todo.rst | 13 + arch/sh/boards/mach-ecovec24/setup.c | 2 +- arch/sh/boards/mach-kfr2r09/setup.c | 2 +- drivers/staging/fbtft/Kconfig | 1 + drivers/video/backlight/bd6107.c | 2 +- drivers/video/backlight/gpio_backlight.c | 6 +- drivers/video/backlight/lv5207lp.c | 2 +- drivers/video/fbdev/Kconfig | 13 + drivers/video/fbdev/aty/aty128fb.c | 12 +- drivers/video/fbdev/aty/atyfb_base.c | 18 +- drivers/video/fbdev/aty/radeon_backlight.c | 2 +- drivers/video/fbdev/aty/radeon_base.c | 3 +- drivers/video/fbdev/broadsheetfb.c | 2 +- drivers/video/fbdev/core/Makefile | 7 +- drivers/video/fbdev/core/fb_backlight.c | 33 ++ drivers/video/fbdev/core/fb_info.c | 78 +++ drivers/video/fbdev/core/fb_internal.h | 67 +++ drivers/video/fbdev/core/fb_procfs.c | 62 ++ drivers/video/fbdev/core/fbcon.c | 1 + drivers/video/fbdev/core/fbmem.c | 592 +------------------ drivers/video/fbdev/core/fbsysfs.c | 134 +---- drivers/video/fbdev/ep93xx-fb.c | 21 +- drivers/video/fbdev/fsl-diu-fb.c | 26 +- drivers/video/fbdev/mb862xx/mb862xxfbdrv.c | 9 +- drivers/video/fbdev/metronomefb.c | 2 +- drivers/video/fbdev/nvidia/nv_backlight.c | 2 +- drivers/video/fbdev/nvidia/nvidia.c | 8 +- drivers/video/fbdev/omap2/omapfb/Kconfig | 2 +- drivers/video/fbdev/pxa168fb.c | 2 +- drivers/video/fbdev/riva/fbdev.c | 10 +- drivers/video/fbdev/sh7760fb.c | 50 +- drivers/video/fbdev/sm501fb.c | 2 +- drivers/video/fbdev/smscufx.c | 4 +- drivers/video/fbdev/tdfxfb.c | 4 +- include/linux/fb.h | 6 +- include/linux/platform_data/bd6107.h | 2 +- include/linux/platform_data/gpio_backlight.h | 2 +- include/linux/platform_data/lv5207lp.h | 2 +- 38 files changed, 437 insertions(+), 769 deletions(-) create mode 100644 drivers/video/fbdev/core/fb_backlight.c create mode 100644 drivers/video/fbdev/core/fb_info.c create mode 100644 drivers/video/fbdev/core/fb_internal.h create mode 100644 drivers/video/fbdev/core/fb_procfs.c base-commit: 63a468ec7c7652afa80e3fa6ad203f9e64d04e83 prerequisite-patch-id: 0aa359f6144c4015c140c8a6750be19099c676fb prerequisite-patch-id: c67e5d886a47b7d0266d81100837557fda34cb24 prerequisite-patch-id: cbc453ee02fae02af22fbfdce56ab732c7a88c36 prerequisite-patch-id: 7c401614cf55c033f742bced317575b9f5b77bb1 prerequisite-patch-id: d3145eae4b35a1290199af6ff6cd5abfebc82033 prerequisite-patch-id: 242b6bc45675f1f1a62572542d75c89d4864f15a