When newer VM flags are being created, such as VM_MTE, it becomes necessary
for mmap/mprotect to verify if certain flags are being applied to an
anonymous VMA.
To solve this, one approach is adding a VM flag to track that MAP_ANONYMOUS
is specified [1], and then using the flag in arch_validate_flags().
Another approach is passing vma_is_anonymous() to arch_validate_flags().
To prepare the introduction of PROT_SHSTK, which creates a shadow stack
mapping and can only be applied to an anonymous VMA, update arch_validate_
flags() to include anonymous VMA information.
[1] commit 9f3419315f3c ("arm64: mte: Add PROT_MTE support to mmap() and mprotect()"),
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@xxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
---
arch/arm64/include/asm/mman.h | 4 ++--
arch/sparc/include/asm/mman.h | 4 ++--
include/linux/mman.h | 2 +-
mm/mmap.c | 2 +-
mm/mprotect.c | 2 +-
5 files changed, 7 insertions(+), 7 deletions(-)
diff --git a/arch/arm64/include/asm/mman.h b/arch/arm64/include/asm/mman.h
index e3e28f7daf62..44add1a09041 100644
--- a/arch/arm64/include/asm/mman.h
+++ b/arch/arm64/include/asm/mman.h
@@ -74,7 +74,7 @@ static inline bool arch_validate_prot(unsigned long prot,
}
#define arch_validate_prot(prot, addr) arch_validate_prot(prot, addr)
-static inline bool arch_validate_flags(unsigned long vm_flags)
+static inline bool arch_validate_flags(unsigned long vm_flags, bool is_anon)
{
if (!system_supports_mte())
return true;
@@ -82,6 +82,6 @@ static inline bool arch_validate_flags(unsigned long vm_flags)
/* only allow VM_MTE if VM_MTE_ALLOWED has been set previously */
return !(vm_flags & VM_MTE) || (vm_flags & VM_MTE_ALLOWED);
}
-#define arch_validate_flags(vm_flags) arch_validate_flags(vm_flags)
+#define arch_validate_flags(vm_flags, is_anon) arch_validate_flags(vm_flags, is_anon)
#endif /* ! __ASM_MMAN_H__ */
diff --git a/arch/sparc/include/asm/mman.h b/arch/sparc/include/asm/mman.h
index 274217e7ed70..4a897c8a3f1a 100644
--- a/arch/sparc/include/asm/mman.h
+++ b/arch/sparc/include/asm/mman.h
@@ -60,11 +60,11 @@ static inline int sparc_validate_prot(unsigned long prot, unsigned long addr)
return 1;
}
-#define arch_validate_flags(vm_flags) arch_validate_flags(vm_flags)
+#define arch_validate_flags(vm_flags, is_anon) arch_validate_flags(vm_flags, is_anon)
/* arch_validate_flags() - Ensure combination of flags is valid for a
* VMA.
*/
-static inline bool arch_validate_flags(unsigned long vm_flags)
+static inline bool arch_validate_flags(unsigned long vm_flags, bool is_anon)
{
/* If ADI is being enabled on this VMA, check for ADI
* capability on the platform and ensure VMA is suitable
diff --git a/include/linux/mman.h b/include/linux/mman.h
index 629cefc4ecba..a22ed4495d13 100644
--- a/include/linux/mman.h
+++ b/include/linux/mman.h
@@ -114,7 +114,7 @@ static inline bool arch_validate_prot(unsigned long prot, unsigned long addr)
*
* Returns true if the VM_* flags are valid.
*/
-static inline bool arch_validate_flags(unsigned long flags)
+static inline bool arch_validate_flags(unsigned long flags, bool is_anonymous)
{
return true;
}
diff --git a/mm/mmap.c b/mm/mmap.c
index 7b2992ef8ee0..db849e3ed9d3 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1850,7 +1850,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
}
/* Allow architectures to sanity-check the vm_flags */
- if (!arch_validate_flags(vma->vm_flags)) {
+ if (!arch_validate_flags(vma->vm_flags, vma_is_anonymous(vma))) {
error = -EINVAL;
if (file)
goto unmap_and_free_vma;
diff --git a/mm/mprotect.c b/mm/mprotect.c
index 3b2f0d75519f..64378b963548 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -611,7 +611,7 @@ static int do_mprotect_pkey(unsigned long start, size_t len,
}
/* Allow architectures to sanity-check the new flags */
- if (!arch_validate_flags(newflags)) {
+ if (!arch_validate_flags(newflags, vma_is_anonymous(vma))) {
error = -EINVAL;
goto out;
}
--
2.21.0
