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.
Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
Cc: Kees Cook <keesc...@chromium.org>
Cc: Andy Lutomirski <l...@amacapital.net>
Cc: Will Drewry <w...@chromium.org>
Cc: Andrew Morton <a...@linux-foundation.org>
Cc: Dave Airlie <airl...@gmail.com>
Cc: Daniel Vetter <dan...@ffwll.ch>
Cc: Lucas Stach <l.st...@pengutronix.de>
---
init/Kconfig | 11 +++++++++++
kernel/Makefile | 2 +-
tools/testing/selftests/seccomp/seccomp_bpf.c | 2 +-
3 files changed, 13 insertions(+), 2 deletions(-)
diff --git a/init/Kconfig b/init/Kconfig
index b77c60f8b963..f62fca13ac5b 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 +1738,16 @@ config ARCH_HAS_MEMBARRIER_CALLBACKS
config ARCH_HAS_MEMBARRIER_SYNC_CORE
bool
+config KCMP
+ bool "Enable kcmp() system call" if EXPERT
+ default y
+ help
+ Enable the file descriptor comparison system call. It provides
+ user-space with the ability to compare two fd to see if they
+ point to the same file, and check other attributes.
+
+ If unsure, say Y.
+
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
