From cb1a393c40eee2f1692c995ea0cc6e45bfccde4d Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Wed, 14 Feb 2024 13:29:28 +0100 Subject: mm: add arch hook to validate mmap() prot flags Add a hook to permit architectures to perform validation on the prot flags passed to mmap(), like arch_validate_prot() does for mprotect(). This will be used by arm64 to reject PROT_WRITE+PROT_EXEC mappings on configurations that run with WXN enabled. Reviewed-by: Kees Cook Signed-off-by: Ard Biesheuvel Link: https://lore.kernel.org/r/20240214122845.2033971-87-ardb+git@google.com Signed-off-by: Catalin Marinas --- include/linux/mman.h | 15 +++++++++++++++ 1 file changed, 15 insertions(+) (limited to 'include') diff --git a/include/linux/mman.h b/include/linux/mman.h index dc7048824be8..ec5e7f606e43 100644 --- a/include/linux/mman.h +++ b/include/linux/mman.h @@ -124,6 +124,21 @@ static inline bool arch_validate_flags(unsigned long flags) #define arch_validate_flags arch_validate_flags #endif +#ifndef arch_validate_mmap_prot +/* + * This is called from mmap(), which ignores unknown prot bits so the default + * is to accept anything. + * + * Returns true if the prot flags are valid + */ +static inline bool arch_validate_mmap_prot(unsigned long prot, + unsigned long addr) +{ + return true; +} +#define arch_validate_mmap_prot arch_validate_mmap_prot +#endif + /* * Optimisation macro. It is equivalent to: * (x & bit1) ? bit2 : 0 -- cgit v1.2.3