| Message ID | 20210205210610.29837-1-chris@chris-wilson.co.uk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] kernel: Expose SYS_kcmp by default | expand |
The subject should of course be changed, as it is no longer being enabled by default. Something like kcmp: Support selection of SYS_kcmp without CHECKPOINT_RESTORE Quoting Chris Wilson (2021-02-05 21:06:10) > Userspace has discovered the functionality offered by SYS_kcmp and has > started to depend upon it. In particular, Mesa uses SYS_kcmp for > os_same_file_description() in order to identify when two fd (e.g. device > or dmabuf) point to the same struct file. Since they depend on it for > core functionality, lift SYS_kcmp out of the non-default > CONFIG_CHECKPOINT_RESTORE into the selectable syscall category. > > Note that some distributions such as Ubuntu are already enabling > CHECKPOINT_RESTORE in their configs and so, by extension, SYS_kcmp. > > References: https://gitlab.freedesktop.org/drm/intel/-/issues/3046 > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> > Cc: Kees Cook <keescook@chromium.org> > Cc: Andy Lutomirski <luto@amacapital.net> > Cc: Will Drewry <wad@chromium.org> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Dave Airlie <airlied@gmail.com> > Cc: Daniel Vetter <daniel@ffwll.ch> > Cc: Lucas Stach <l.stach@pengutronix.de> > Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> # DRM depends on SYS_kcmp > > --- > v2: > - Default n. > - Borrrow help message from man kcmp. > - Export get_epoll_tfile_raw_ptr() for CONFIG_KCMP > --- > fs/eventpoll.c | 4 ++-- > include/linux/eventpoll.h | 2 +- > init/Kconfig | 12 ++++++++++++ > kernel/Makefile | 2 +- > tools/testing/selftests/seccomp/seccomp_bpf.c | 2 +- > 5 files changed, 17 insertions(+), 5 deletions(-) > > diff --git a/fs/eventpoll.c b/fs/eventpoll.c > index a829af074eb5..3196474cbe24 100644 > --- a/fs/eventpoll.c > +++ b/fs/eventpoll.c > @@ -979,7 +979,7 @@ static struct epitem *ep_find(struct eventpoll *ep, struct file *file, int fd) > return epir; > } > > -#ifdef CONFIG_CHECKPOINT_RESTORE > +#ifdef CONFIG_KCMP > static struct epitem *ep_find_tfd(struct eventpoll *ep, int tfd, unsigned long toff) > { > struct rb_node *rbp; > @@ -1021,7 +1021,7 @@ struct file *get_epoll_tfile_raw_ptr(struct file *file, int tfd, > > return file_raw; > } > -#endif /* CONFIG_CHECKPOINT_RESTORE */ > +#endif /* CONFIG_KCMP */ > > /** > * Adds a new entry to the tail of the list in a lockless way, i.e. > diff --git a/include/linux/eventpoll.h b/include/linux/eventpoll.h > index 0350393465d4..593322c946e6 100644 > --- a/include/linux/eventpoll.h > +++ b/include/linux/eventpoll.h > @@ -18,7 +18,7 @@ struct file; > > #ifdef CONFIG_EPOLL > > -#ifdef CONFIG_CHECKPOINT_RESTORE > +#ifdef CONFIG_KCMP > struct file *get_epoll_tfile_raw_ptr(struct file *file, int tfd, unsigned long toff); > #endif > > diff --git a/init/Kconfig b/init/Kconfig > index b77c60f8b963..1b75141bc18b 100644 > --- a/init/Kconfig > +++ b/init/Kconfig > @@ -1194,6 +1194,7 @@ endif # NAMESPACES > config CHECKPOINT_RESTORE > bool "Checkpoint/restore support" > select PROC_CHILDREN > + select KCMP > default n > help > Enables additional kernel features in a sake of checkpoint/restore. > @@ -1737,6 +1738,17 @@ config ARCH_HAS_MEMBARRIER_CALLBACKS > config ARCH_HAS_MEMBARRIER_SYNC_CORE > bool > > +config KCMP > + bool "Enable kcmp() system call" if EXPERT > + default n > + help > + Enable the kernel resource comparison system call. It provides > + user-space with the ability to compare two processes to see if they > + share a common resource, such as a file descriptor or even virtual > + memory space. > + > + If unsure, say N. > + > config RSEQ > bool "Enable rseq() system call" if EXPERT > default y > diff --git a/kernel/Makefile b/kernel/Makefile > index aa7368c7eabf..320f1f3941b7 100644 > --- a/kernel/Makefile > +++ b/kernel/Makefile > @@ -51,7 +51,7 @@ obj-y += livepatch/ > obj-y += dma/ > obj-y += entry/ > > -obj-$(CONFIG_CHECKPOINT_RESTORE) += kcmp.o > +obj-$(CONFIG_KCMP) += kcmp.o > obj-$(CONFIG_FREEZER) += freezer.o > obj-$(CONFIG_PROFILING) += profile.o > obj-$(CONFIG_STACKTRACE) += stacktrace.o > diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c > index 26c72f2b61b1..1b6c7d33c4ff 100644 > --- a/tools/testing/selftests/seccomp/seccomp_bpf.c > +++ b/tools/testing/selftests/seccomp/seccomp_bpf.c > @@ -315,7 +315,7 @@ TEST(kcmp) > ret = __filecmp(getpid(), getpid(), 1, 1); > EXPECT_EQ(ret, 0); > if (ret != 0 && errno == ENOSYS) > - SKIP(return, "Kernel does not support kcmp() (missing CONFIG_CHECKPOINT_RESTORE?)"); > + SKIP(return, "Kernel does not support kcmp() (missing CONFIG_KCMP?)"); > } > > TEST(mode_strict_support) > -- > 2.20.1 >
On Fri, Feb 05, 2021 at 09:16:01PM +0000, Chris Wilson wrote: > The subject should of course be changed, as it is no longer being > enabled by default. "default n" is redundant. I thought Daniel said CONFIG_DRM needed to "select" it too, though? Otherwise, yeah, this looks good. Was the export due to the 0-day bot failure reports? -Kees > > Something like > > kcmp: Support selection of SYS_kcmp without CHECKPOINT_RESTORE > > Quoting Chris Wilson (2021-02-05 21:06:10) > > Userspace has discovered the functionality offered by SYS_kcmp and has > > started to depend upon it. In particular, Mesa uses SYS_kcmp for > > os_same_file_description() in order to identify when two fd (e.g. device > > or dmabuf) point to the same struct file. Since they depend on it for > > core functionality, lift SYS_kcmp out of the non-default > > CONFIG_CHECKPOINT_RESTORE into the selectable syscall category. > > > > Note that some distributions such as Ubuntu are already enabling > > CHECKPOINT_RESTORE in their configs and so, by extension, SYS_kcmp. > > > > References: https://gitlab.freedesktop.org/drm/intel/-/issues/3046 > > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> > > Cc: Kees Cook <keescook@chromium.org> > > Cc: Andy Lutomirski <luto@amacapital.net> > > Cc: Will Drewry <wad@chromium.org> > > Cc: Andrew Morton <akpm@linux-foundation.org> > > Cc: Dave Airlie <airlied@gmail.com> > > Cc: Daniel Vetter <daniel@ffwll.ch> > > Cc: Lucas Stach <l.stach@pengutronix.de> > > Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> # DRM depends on SYS_kcmp > > > > --- > > v2: > > - Default n. > > - Borrrow help message from man kcmp. > > - Export get_epoll_tfile_raw_ptr() for CONFIG_KCMP > > --- > > fs/eventpoll.c | 4 ++-- > > include/linux/eventpoll.h | 2 +- > > init/Kconfig | 12 ++++++++++++ > > kernel/Makefile | 2 +- > > tools/testing/selftests/seccomp/seccomp_bpf.c | 2 +- > > 5 files changed, 17 insertions(+), 5 deletions(-) > > > > diff --git a/fs/eventpoll.c b/fs/eventpoll.c > > index a829af074eb5..3196474cbe24 100644 > > --- a/fs/eventpoll.c > > +++ b/fs/eventpoll.c > > @@ -979,7 +979,7 @@ static struct epitem *ep_find(struct eventpoll *ep, struct file *file, int fd) > > return epir; > > } > > > > -#ifdef CONFIG_CHECKPOINT_RESTORE > > +#ifdef CONFIG_KCMP > > static struct epitem *ep_find_tfd(struct eventpoll *ep, int tfd, unsigned long toff) > > { > > struct rb_node *rbp; > > @@ -1021,7 +1021,7 @@ struct file *get_epoll_tfile_raw_ptr(struct file *file, int tfd, > > > > return file_raw; > > } > > -#endif /* CONFIG_CHECKPOINT_RESTORE */ > > +#endif /* CONFIG_KCMP */ > > > > /** > > * Adds a new entry to the tail of the list in a lockless way, i.e. > > diff --git a/include/linux/eventpoll.h b/include/linux/eventpoll.h > > index 0350393465d4..593322c946e6 100644 > > --- a/include/linux/eventpoll.h > > +++ b/include/linux/eventpoll.h > > @@ -18,7 +18,7 @@ struct file; > > > > #ifdef CONFIG_EPOLL > > > > -#ifdef CONFIG_CHECKPOINT_RESTORE > > +#ifdef CONFIG_KCMP > > struct file *get_epoll_tfile_raw_ptr(struct file *file, int tfd, unsigned long toff); > > #endif > > > > diff --git a/init/Kconfig b/init/Kconfig > > index b77c60f8b963..1b75141bc18b 100644 > > --- a/init/Kconfig > > +++ b/init/Kconfig > > @@ -1194,6 +1194,7 @@ endif # NAMESPACES > > config CHECKPOINT_RESTORE > > bool "Checkpoint/restore support" > > select PROC_CHILDREN > > + select KCMP > > default n > > help > > Enables additional kernel features in a sake of checkpoint/restore. > > @@ -1737,6 +1738,17 @@ config ARCH_HAS_MEMBARRIER_CALLBACKS > > config ARCH_HAS_MEMBARRIER_SYNC_CORE > > bool > > > > +config KCMP > > + bool "Enable kcmp() system call" if EXPERT > > + default n > > + help > > + Enable the kernel resource comparison system call. It provides > > + user-space with the ability to compare two processes to see if they > > + share a common resource, such as a file descriptor or even virtual > > + memory space. > > + > > + If unsure, say N. > > + > > config RSEQ > > bool "Enable rseq() system call" if EXPERT > > default y > > diff --git a/kernel/Makefile b/kernel/Makefile > > index aa7368c7eabf..320f1f3941b7 100644 > > --- a/kernel/Makefile > > +++ b/kernel/Makefile > > @@ -51,7 +51,7 @@ obj-y += livepatch/ > > obj-y += dma/ > > obj-y += entry/ > > > > -obj-$(CONFIG_CHECKPOINT_RESTORE) += kcmp.o > > +obj-$(CONFIG_KCMP) += kcmp.o > > obj-$(CONFIG_FREEZER) += freezer.o > > obj-$(CONFIG_PROFILING) += profile.o > > obj-$(CONFIG_STACKTRACE) += stacktrace.o > > diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c > > index 26c72f2b61b1..1b6c7d33c4ff 100644 > > --- a/tools/testing/selftests/seccomp/seccomp_bpf.c > > +++ b/tools/testing/selftests/seccomp/seccomp_bpf.c > > @@ -315,7 +315,7 @@ TEST(kcmp) > > ret = __filecmp(getpid(), getpid(), 1, 1); > > EXPECT_EQ(ret, 0); > > if (ret != 0 && errno == ENOSYS) > > - SKIP(return, "Kernel does not support kcmp() (missing CONFIG_CHECKPOINT_RESTORE?)"); > > + SKIP(return, "Kernel does not support kcmp() (missing CONFIG_KCMP?)"); > > } > > > > TEST(mode_strict_support) > > -- > > 2.20.1 > >
Quoting Kees Cook (2021-02-05 21:20:33) > On Fri, Feb 05, 2021 at 09:16:01PM +0000, Chris Wilson wrote: > > The subject should of course be changed, as it is no longer being > > enabled by default. > > "default n" is redundant. I thought being explicit would be preferred. There are a few other default n, so at least it's not the odd-one-out! > I thought Daniel said CONFIG_DRM needed to > "select" it too, though? Yes. We will need to select it for any DRM driver so that the Vulkan/GL stacks can rely on having SYS_kcmp. That deserves to be handled and explain within drm/Kconfig, and as they are already shipping with calls to SYS_kcmp we may have to ask for a stable backport. > Otherwise, yeah, this looks good. Was the > export due to the 0-day bot failure reports? Yes. -Chris
On 05/02/2021 22.06, Chris Wilson wrote: > Userspace has discovered the functionality offered by SYS_kcmp and has > started to depend upon it. In particular, Mesa uses SYS_kcmp for > os_same_file_description() in order to identify when two fd (e.g. device > or dmabuf) point to the same struct file. Since they depend on it for > core functionality, lift SYS_kcmp out of the non-default > CONFIG_CHECKPOINT_RESTORE into the selectable syscall category. > > Note that some distributions such as Ubuntu are already enabling > CHECKPOINT_RESTORE in their configs and so, by extension, SYS_kcmp. > Looks a lot like https://lore.kernel.org/lkml/20200710075632.14661-1-linux@rasmusvillemoes.dk/. So FWIW, ack from me. cc += Cyrill. > References: https://gitlab.freedesktop.org/drm/intel/-/issues/3046 > Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> > Cc: Kees Cook <keescook@chromium.org> > Cc: Andy Lutomirski <luto@amacapital.net> > Cc: Will Drewry <wad@chromium.org> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Dave Airlie <airlied@gmail.com> > Cc: Daniel Vetter <daniel@ffwll.ch> > Cc: Lucas Stach <l.stach@pengutronix.de> > Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> # DRM depends on SYS_kcmp > > --- > v2: > - Default n. > - Borrrow help message from man kcmp. > - Export get_epoll_tfile_raw_ptr() for CONFIG_KCMP > --- > fs/eventpoll.c | 4 ++-- > include/linux/eventpoll.h | 2 +- > init/Kconfig | 12 ++++++++++++ > kernel/Makefile | 2 +- > tools/testing/selftests/seccomp/seccomp_bpf.c | 2 +- > 5 files changed, 17 insertions(+), 5 deletions(-) > > diff --git a/fs/eventpoll.c b/fs/eventpoll.c > index a829af074eb5..3196474cbe24 100644 > --- a/fs/eventpoll.c > +++ b/fs/eventpoll.c > @@ -979,7 +979,7 @@ static struct epitem *ep_find(struct eventpoll *ep, struct file *file, int fd) > return epir; > } > > -#ifdef CONFIG_CHECKPOINT_RESTORE > +#ifdef CONFIG_KCMP > static struct epitem *ep_find_tfd(struct eventpoll *ep, int tfd, unsigned long toff) > { > struct rb_node *rbp; > @@ -1021,7 +1021,7 @@ struct file *get_epoll_tfile_raw_ptr(struct file *file, int tfd, > > return file_raw; > } > -#endif /* CONFIG_CHECKPOINT_RESTORE */ > +#endif /* CONFIG_KCMP */ > > /** > * Adds a new entry to the tail of the list in a lockless way, i.e. > diff --git a/include/linux/eventpoll.h b/include/linux/eventpoll.h > index 0350393465d4..593322c946e6 100644 > --- a/include/linux/eventpoll.h > +++ b/include/linux/eventpoll.h > @@ -18,7 +18,7 @@ struct file; > > #ifdef CONFIG_EPOLL > > -#ifdef CONFIG_CHECKPOINT_RESTORE > +#ifdef CONFIG_KCMP > struct file *get_epoll_tfile_raw_ptr(struct file *file, int tfd, unsigned long toff); > #endif > > diff --git a/init/Kconfig b/init/Kconfig > index b77c60f8b963..1b75141bc18b 100644 > --- a/init/Kconfig > +++ b/init/Kconfig > @@ -1194,6 +1194,7 @@ endif # NAMESPACES > config CHECKPOINT_RESTORE > bool "Checkpoint/restore support" > select PROC_CHILDREN > + select KCMP > default n > help > Enables additional kernel features in a sake of checkpoint/restore. > @@ -1737,6 +1738,17 @@ config ARCH_HAS_MEMBARRIER_CALLBACKS > config ARCH_HAS_MEMBARRIER_SYNC_CORE > bool > > +config KCMP > + bool "Enable kcmp() system call" if EXPERT > + default n > + help > + Enable the kernel resource comparison system call. It provides > + user-space with the ability to compare two processes to see if they > + share a common resource, such as a file descriptor or even virtual > + memory space. > + > + If unsure, say N. > + > config RSEQ > bool "Enable rseq() system call" if EXPERT > default y > diff --git a/kernel/Makefile b/kernel/Makefile > index aa7368c7eabf..320f1f3941b7 100644 > --- a/kernel/Makefile > +++ b/kernel/Makefile > @@ -51,7 +51,7 @@ obj-y += livepatch/ > obj-y += dma/ > obj-y += entry/ > > -obj-$(CONFIG_CHECKPOINT_RESTORE) += kcmp.o > +obj-$(CONFIG_KCMP) += kcmp.o > obj-$(CONFIG_FREEZER) += freezer.o > obj-$(CONFIG_PROFILING) += profile.o > obj-$(CONFIG_STACKTRACE) += stacktrace.o > diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c > index 26c72f2b61b1..1b6c7d33c4ff 100644 > --- a/tools/testing/selftests/seccomp/seccomp_bpf.c > +++ b/tools/testing/selftests/seccomp/seccomp_bpf.c > @@ -315,7 +315,7 @@ TEST(kcmp) > ret = __filecmp(getpid(), getpid(), 1, 1); > EXPECT_EQ(ret, 0); > if (ret != 0 && errno == ENOSYS) > - SKIP(return, "Kernel does not support kcmp() (missing CONFIG_CHECKPOINT_RESTORE?)"); > + SKIP(return, "Kernel does not support kcmp() (missing CONFIG_KCMP?)"); > } > > TEST(mode_strict_support) >
On Fri, Feb 5, 2021 at 10:28 PM Chris Wilson <chris@chris-wilson.co.uk> wrote: > > Quoting Kees Cook (2021-02-05 21:20:33) > > On Fri, Feb 05, 2021 at 09:16:01PM +0000, Chris Wilson wrote: > > > The subject should of course be changed, as it is no longer being > > > enabled by default. > > > > "default n" is redundant. > > I thought being explicit would be preferred. There are a few other > default n, so at least it's not the odd-one-out! > > > I thought Daniel said CONFIG_DRM needed to > > "select" it too, though? > > Yes. We will need to select it for any DRM driver so that the Vulkan/GL > stacks can rely on having SYS_kcmp. That deserves to be handled and > explain within drm/Kconfig, and as they are already shipping with calls > to SYS_kcmp we may have to ask for a stable backport. Oh I dreamed and thought it's part of this patch already. So v3 with matching subject to enabled it for drm? -Daniel > > > Otherwise, yeah, this looks good. Was the > > export due to the 0-day bot failure reports? > > Yes. > -Chris
diff --git a/fs/eventpoll.c b/fs/eventpoll.c index a829af074eb5..3196474cbe24 100644 --- a/fs/eventpoll.c +++ b/fs/eventpoll.c @@ -979,7 +979,7 @@ static struct epitem *ep_find(struct eventpoll *ep, struct file *file, int fd) return epir; } -#ifdef CONFIG_CHECKPOINT_RESTORE +#ifdef CONFIG_KCMP static struct epitem *ep_find_tfd(struct eventpoll *ep, int tfd, unsigned long toff) { struct rb_node *rbp; @@ -1021,7 +1021,7 @@ struct file *get_epoll_tfile_raw_ptr(struct file *file, int tfd, return file_raw; } -#endif /* CONFIG_CHECKPOINT_RESTORE */ +#endif /* CONFIG_KCMP */ /** * Adds a new entry to the tail of the list in a lockless way, i.e. diff --git a/include/linux/eventpoll.h b/include/linux/eventpoll.h index 0350393465d4..593322c946e6 100644 --- a/include/linux/eventpoll.h +++ b/include/linux/eventpoll.h @@ -18,7 +18,7 @@ struct file; #ifdef CONFIG_EPOLL -#ifdef CONFIG_CHECKPOINT_RESTORE +#ifdef CONFIG_KCMP struct file *get_epoll_tfile_raw_ptr(struct file *file, int tfd, unsigned long toff); #endif diff --git a/init/Kconfig b/init/Kconfig index b77c60f8b963..1b75141bc18b 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -1194,6 +1194,7 @@ endif # NAMESPACES config CHECKPOINT_RESTORE bool "Checkpoint/restore support" select PROC_CHILDREN + select KCMP default n help Enables additional kernel features in a sake of checkpoint/restore. @@ -1737,6 +1738,17 @@ config ARCH_HAS_MEMBARRIER_CALLBACKS config ARCH_HAS_MEMBARRIER_SYNC_CORE bool +config KCMP + bool "Enable kcmp() system call" if EXPERT + default n + help + Enable the kernel resource comparison system call. It provides + user-space with the ability to compare two processes to see if they + share a common resource, such as a file descriptor or even virtual + memory space. + + If unsure, say N. + config RSEQ bool "Enable rseq() system call" if EXPERT default y diff --git a/kernel/Makefile b/kernel/Makefile index aa7368c7eabf..320f1f3941b7 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -51,7 +51,7 @@ obj-y += livepatch/ obj-y += dma/ obj-y += entry/ -obj-$(CONFIG_CHECKPOINT_RESTORE) += kcmp.o +obj-$(CONFIG_KCMP) += kcmp.o obj-$(CONFIG_FREEZER) += freezer.o obj-$(CONFIG_PROFILING) += profile.o obj-$(CONFIG_STACKTRACE) += stacktrace.o diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c index 26c72f2b61b1..1b6c7d33c4ff 100644 --- a/tools/testing/selftests/seccomp/seccomp_bpf.c +++ b/tools/testing/selftests/seccomp/seccomp_bpf.c @@ -315,7 +315,7 @@ TEST(kcmp) ret = __filecmp(getpid(), getpid(), 1, 1); EXPECT_EQ(ret, 0); if (ret != 0 && errno == ENOSYS) - SKIP(return, "Kernel does not support kcmp() (missing CONFIG_CHECKPOINT_RESTORE?)"); + SKIP(return, "Kernel does not support kcmp() (missing CONFIG_KCMP?)"); } TEST(mode_strict_support)