[PATCH RFC bpf-next 3/8] bpf: add BPF_JIT_KASAN for KASAN instrumentation of JITed programs

["Alexis Lothoré (eBPF Foundation)" <alexis.lothore@bootlin.com>]

Add a new Kconfig option CONFIG_BPF_JIT_KASAN that automatically enables
KASAN (Kernel Address Sanitizer) memory access checks for JIT-compiled
BPF programs, when both KASAN and JIT compiler are enabled. When
enabled, the JIT compiler will emit shadow memory checks before memory
loads and stores to detect use-after-free, out-of-bounds, and other
memory safety bugs at runtime. The option is gated behind
HAVE_EBPF_JIT_KASAN, as it needs proper arch-specific implementation.

Signed-off-by: Alexis Lothoré (eBPF Foundation) <alexis.lothore@bootlin.com>
---
 kernel/bpf/Kconfig | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/kernel/bpf/Kconfig b/kernel/bpf/Kconfig
index eb3de35734f0..28392adb3d7e 100644
--- a/kernel/bpf/Kconfig
+++ b/kernel/bpf/Kconfig
@@ -17,6 +17,10 @@ config HAVE_CBPF_JIT
 config HAVE_EBPF_JIT
 	bool
 
+# KASAN support for JIT compiler
+config HAVE_EBPF_JIT_KASAN
+	bool
+
 # Used by archs to tell that they want the BPF JIT compiler enabled by
 # default for kernels that were compiled with BPF JIT support.
 config ARCH_WANT_DEFAULT_BPF_JIT
@@ -101,4 +105,9 @@ config BPF_LSM
 
 	  If you are unsure how to answer this question, answer N.
 
+config BPF_JIT_KASAN
+	bool
+	depends on HAVE_EBPF_JIT_KASAN
+	default y if BPF_JIT && KASAN_GENERIC
+
 endmenu # "BPF subsystem"

-- 
2.53.0