diff options
Diffstat (limited to 'tools/testing/vma/vma_internal.h')
| -rw-r--r-- | tools/testing/vma/vma_internal.h | 65 |
1 files changed, 65 insertions, 0 deletions
diff --git a/tools/testing/vma/vma_internal.h b/tools/testing/vma/vma_internal.h index ae635eecbfa8..2404347fa2c7 100644 --- a/tools/testing/vma/vma_internal.h +++ b/tools/testing/vma/vma_internal.h @@ -41,6 +41,8 @@ extern unsigned long dac_mmap_min_addr; #define VM_BUG_ON(_expr) (BUG_ON(_expr)) #define VM_BUG_ON_VMA(_expr, _vma) (BUG_ON(_expr)) +#define MMF_HAS_MDWE 28 + #define VM_NONE 0x00000000 #define VM_READ 0x00000001 #define VM_WRITE 0x00000002 @@ -226,6 +228,8 @@ struct mm_struct { unsigned long stack_vm; /* VM_STACK */ unsigned long def_flags; + + unsigned long flags; /* Must use atomic bitops to access */ }; struct vma_lock { @@ -1185,4 +1189,65 @@ static inline void userfaultfd_unmap_complete(struct mm_struct *mm, { } +/* + * Denies creating a writable executable mapping or gaining executable permissions. + * + * This denies the following: + * + * a) mmap(PROT_WRITE | PROT_EXEC) + * + * b) mmap(PROT_WRITE) + * mprotect(PROT_EXEC) + * + * c) mmap(PROT_WRITE) + * mprotect(PROT_READ) + * mprotect(PROT_EXEC) + * + * But allows the following: + * + * d) mmap(PROT_READ | PROT_EXEC) + * mmap(PROT_READ | PROT_EXEC | PROT_BTI) + * + * This is only applicable if the user has set the Memory-Deny-Write-Execute + * (MDWE) protection mask for the current process. + * + * @old specifies the VMA flags the VMA originally possessed, and @new the ones + * we propose to set. + * + * Return: false if proposed change is OK, true if not ok and should be denied. + */ +static inline bool map_deny_write_exec(unsigned long old, unsigned long new) +{ + /* If MDWE is disabled, we have nothing to deny. */ + if (!test_bit(MMF_HAS_MDWE, ¤t->mm->flags)) + return false; + + /* If the new VMA is not executable, we have nothing to deny. */ + if (!(new & VM_EXEC)) + return false; + + /* Under MDWE we do not accept newly writably executable VMAs... */ + if (new & VM_WRITE) + return true; + + /* ...nor previously non-executable VMAs becoming executable. */ + if (!(old & VM_EXEC)) + return true; + + return false; +} + +static inline int mapping_map_writable(struct address_space *mapping) +{ + int c = atomic_read(&mapping->i_mmap_writable); + + /* Derived from the raw_atomic_inc_unless_negative() implementation. */ + do { + if (c < 0) + return -EPERM; + } while (!__sync_bool_compare_and_swap(&mapping->i_mmap_writable, c, c+1)); + + return 0; +} + #endif /* __MM_VMA_INTERNAL_H */ |