Update the mmap() implementation logic implemented in __mmap_region() and functions invoked by it. The mmap_region() function converts its input vm_flags_t parameter to a vma_flags_t value which it then passes to __mmap_region() which uses the vma_flags_t value consistently from then on.
As part of the change, we convert map_deny_write_exec() to using vma_flags_t (it was incorrectly using unsigned long before), and place it in vma.h, as it is only used internal to mm. With this change, we eliminate the legacy is_shared_maywrite_vm_flags() helper function which is now no longer required. We are also able to update the MMAP_STATE() and VMG_MMAP_STATE() macros to use the vma_flags_t value. Finally, we update the VMA tests to reflect the change. Signed-off-by: Lorenzo Stoakes (Oracle) <[email protected]> --- include/linux/mm.h | 18 ++++++++---- include/linux/mman.h | 49 ------------------------------- mm/mprotect.c | 4 ++- mm/vma.c | 25 ++++++++-------- mm/vma.h | 51 +++++++++++++++++++++++++++++++++ tools/testing/vma/include/dup.h | 34 +++++----------------- tools/testing/vma/tests/mmap.c | 18 ++++-------- 7 files changed, 92 insertions(+), 107 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index fd873a9467f8..34b587531f1b 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1485,12 +1485,6 @@ static inline bool vma_is_accessible(const struct vm_area_struct *vma) return vma->vm_flags & VM_ACCESS_FLAGS; } -static inline bool is_shared_maywrite_vm_flags(vm_flags_t vm_flags) -{ - return (vm_flags & (VM_SHARED | VM_MAYWRITE)) == - (VM_SHARED | VM_MAYWRITE); -} - static inline bool is_shared_maywrite(const vma_flags_t *flags) { return vma_flags_test_all(flags, VMA_SHARED_BIT, VMA_MAYWRITE_BIT); @@ -4285,12 +4279,24 @@ static inline bool range_in_vma(const struct vm_area_struct *vma, #ifdef CONFIG_MMU pgprot_t vm_get_page_prot(vm_flags_t vm_flags); + +static inline pgprot_t vma_get_page_prot(vma_flags_t vma_flags) +{ + const vm_flags_t vm_flags = vma_flags_to_legacy(vma_flags); + + return vm_get_page_prot(vm_flags); +} + void vma_set_page_prot(struct vm_area_struct *vma); #else static inline pgprot_t vm_get_page_prot(vm_flags_t vm_flags) { return __pgprot(0); } +static inline pgprot_t vma_get_page_prot(vma_flags_t vma_flags) +{ + return __pgprot(0); +} static inline void vma_set_page_prot(struct vm_area_struct *vma) { vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); diff --git a/include/linux/mman.h b/include/linux/mman.h index 0ba8a7e8b90a..389521594c69 100644 --- a/include/linux/mman.h +++ b/include/linux/mman.h @@ -170,53 +170,4 @@ static inline bool arch_memory_deny_write_exec_supported(void) } #define arch_memory_deny_write_exec_supported arch_memory_deny_write_exec_supported #endif - -/* - * 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 (!mm_flags_test(MMF_HAS_MDWE, current->mm)) - 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; -} - #endif /* _LINUX_MMAN_H */ diff --git a/mm/mprotect.c b/mm/mprotect.c index 2b8a85689ab7..ef09cd1aa33f 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -882,6 +882,7 @@ static int do_mprotect_pkey(unsigned long start, size_t len, tmp = vma->vm_start; for_each_vma_range(vmi, vma, end) { vm_flags_t mask_off_old_flags; + vma_flags_t new_vma_flags; vm_flags_t newflags; int new_vma_pkey; @@ -904,6 +905,7 @@ static int do_mprotect_pkey(unsigned long start, size_t len, new_vma_pkey = arch_override_mprotect_pkey(vma, prot, pkey); newflags = calc_vm_prot_bits(prot, new_vma_pkey); newflags |= (vma->vm_flags & ~mask_off_old_flags); + new_vma_flags = legacy_to_vma_flags(newflags); /* newflags >> 4 shift VM_MAY% in place of VM_% */ if ((newflags & ~(newflags >> 4)) & VM_ACCESS_FLAGS) { @@ -911,7 +913,7 @@ static int do_mprotect_pkey(unsigned long start, size_t len, break; } - if (map_deny_write_exec(vma->vm_flags, newflags)) { + if (map_deny_write_exec(&vma->flags, &new_vma_flags)) { error = -EACCES; break; } diff --git a/mm/vma.c b/mm/vma.c index c2c649b23465..1b00d6a2cc8d 100644 --- a/mm/vma.c +++ b/mm/vma.c @@ -44,7 +44,7 @@ struct mmap_state { bool file_doesnt_need_get :1; }; -#define MMAP_STATE(name, mm_, vmi_, addr_, len_, pgoff_, vm_flags_, file_) \ +#define MMAP_STATE(name, mm_, vmi_, addr_, len_, pgoff_, vma_flags_, file_) \ struct mmap_state name = { \ .mm = mm_, \ .vmi = vmi_, \ @@ -52,9 +52,9 @@ struct mmap_state { .end = (addr_) + (len_), \ .pgoff = pgoff_, \ .pglen = PHYS_PFN(len_), \ - .vm_flags = vm_flags_, \ + .vma_flags = vma_flags_, \ .file = file_, \ - .page_prot = vm_get_page_prot(vm_flags_), \ + .page_prot = vma_get_page_prot(vma_flags_), \ } #define VMG_MMAP_STATE(name, map_, vma_) \ @@ -63,7 +63,7 @@ struct mmap_state { .vmi = (map_)->vmi, \ .start = (map_)->addr, \ .end = (map_)->end, \ - .vm_flags = (map_)->vm_flags, \ + .vma_flags = (map_)->vma_flags, \ .pgoff = (map_)->pgoff, \ .file = (map_)->file, \ .prev = (map_)->prev, \ @@ -2747,14 +2747,14 @@ static int call_action_complete(struct mmap_state *map, } static unsigned long __mmap_region(struct file *file, unsigned long addr, - unsigned long len, vm_flags_t vm_flags, unsigned long pgoff, - struct list_head *uf) + unsigned long len, vma_flags_t vma_flags, + unsigned long pgoff, struct list_head *uf) { struct mm_struct *mm = current->mm; struct vm_area_struct *vma = NULL; bool have_mmap_prepare = file && file->f_op->mmap_prepare; VMA_ITERATOR(vmi, mm, addr); - MMAP_STATE(map, mm, &vmi, addr, len, pgoff, vm_flags, file); + MMAP_STATE(map, mm, &vmi, addr, len, pgoff, vma_flags, file); struct vm_area_desc desc = { .mm = mm, .file = file, @@ -2838,16 +2838,17 @@ static unsigned long __mmap_region(struct file *file, unsigned long addr, * been performed. */ unsigned long mmap_region(struct file *file, unsigned long addr, - unsigned long len, vm_flags_t vm_flags, unsigned long pgoff, - struct list_head *uf) + unsigned long len, vm_flags_t vm_flags, + unsigned long pgoff, struct list_head *uf) { unsigned long ret; bool writable_file_mapping = false; + const vma_flags_t vma_flags = legacy_to_vma_flags(vm_flags); mmap_assert_write_locked(current->mm); /* Check to see if MDWE is applicable. */ - if (map_deny_write_exec(vm_flags, vm_flags)) + if (map_deny_write_exec(&vma_flags, &vma_flags)) return -EACCES; /* Allow architectures to sanity-check the vm_flags. */ @@ -2855,7 +2856,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr, return -EINVAL; /* Map writable and ensure this isn't a sealed memfd. */ - if (file && is_shared_maywrite_vm_flags(vm_flags)) { + if (file && is_shared_maywrite(&vma_flags)) { int error = mapping_map_writable(file->f_mapping); if (error) @@ -2863,7 +2864,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr, writable_file_mapping = true; } - ret = __mmap_region(file, addr, len, vm_flags, pgoff, uf); + ret = __mmap_region(file, addr, len, vma_flags, pgoff, uf); /* Clear our write mapping regardless of error. */ if (writable_file_mapping) diff --git a/mm/vma.h b/mm/vma.h index 270008e5babc..adc18f7dd9f1 100644 --- a/mm/vma.h +++ b/mm/vma.h @@ -704,4 +704,55 @@ int create_init_stack_vma(struct mm_struct *mm, struct vm_area_struct **vmap, int relocate_vma_down(struct vm_area_struct *vma, unsigned long shift); #endif +#ifdef CONFIG_MMU +/* + * 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(const vma_flags_t *old, + const vma_flags_t *new) +{ + /* If MDWE is disabled, we have nothing to deny. */ + if (!mm_flags_test(MMF_HAS_MDWE, current->mm)) + return false; + + /* If the new VMA is not executable, we have nothing to deny. */ + if (!vma_flags_test(new, VMA_EXEC_BIT)) + return false; + + /* Under MDWE we do not accept newly writably executable VMAs... */ + if (vma_flags_test(new, VMA_WRITE_BIT)) + return true; + + /* ...nor previously non-executable VMAs becoming executable. */ + if (!vma_flags_test(old, VMA_EXEC_BIT)) + return true; + + return false; +} +#endif + #endif /* __MM_VMA_H */ diff --git a/tools/testing/vma/include/dup.h b/tools/testing/vma/include/dup.h index 71bb3559682d..f35c9d31aad3 100644 --- a/tools/testing/vma/include/dup.h +++ b/tools/testing/vma/include/dup.h @@ -1094,12 +1094,6 @@ static __always_inline void vma_desc_clear_flags_mask(struct vm_area_desc *desc, #define vma_desc_clear_flags(desc, ...) \ vma_desc_clear_flags_mask(desc, mk_vma_flags(__VA_ARGS__)) -static inline bool is_shared_maywrite_vm_flags(vm_flags_t vm_flags) -{ - return (vm_flags & (VM_SHARED | VM_MAYWRITE)) == - (VM_SHARED | VM_MAYWRITE); -} - static inline bool is_shared_maywrite(const vma_flags_t *flags) { return vma_flags_test_all(flags, VMA_SHARED_BIT, VMA_MAYWRITE_BIT); @@ -1416,27 +1410,6 @@ static inline bool mlock_future_ok(const struct mm_struct *mm, return locked_pages <= limit_pages; } -static inline bool map_deny_write_exec(unsigned long old, unsigned long new) -{ - /* If MDWE is disabled, we have nothing to deny. */ - if (mm_flags_test(MMF_HAS_MDWE, current->mm)) - 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) { return atomic_inc_unless_negative(&mapping->i_mmap_writable) ? @@ -1482,3 +1455,10 @@ static inline void vma_set_file(struct vm_area_struct *vma, struct file *file) #ifndef pgtable_supports_soft_dirty #define pgtable_supports_soft_dirty() IS_ENABLED(CONFIG_MEM_SOFT_DIRTY) #endif + +static inline pgprot_t vma_get_page_prot(vma_flags_t vma_flags) +{ + const vm_flags_t vm_flags = vma_flags_to_legacy(vma_flags); + + return vm_get_page_prot(vm_flags); +} diff --git a/tools/testing/vma/tests/mmap.c b/tools/testing/vma/tests/mmap.c index bded4ecbe5db..c85bc000d1cb 100644 --- a/tools/testing/vma/tests/mmap.c +++ b/tools/testing/vma/tests/mmap.c @@ -2,6 +2,8 @@ static bool test_mmap_region_basic(void) { + const vma_flags_t vma_flags = mk_vma_flags(VMA_READ_BIT, VMA_WRITE_BIT, + VMA_MAYREAD_BIT, VMA_MAYWRITE_BIT); struct mm_struct mm = {}; unsigned long addr; struct vm_area_struct *vma; @@ -10,27 +12,19 @@ static bool test_mmap_region_basic(void) current->mm = &mm; /* Map at 0x300000, length 0x3000. */ - addr = __mmap_region(NULL, 0x300000, 0x3000, - VM_READ | VM_WRITE | VM_MAYREAD | VM_MAYWRITE, - 0x300, NULL); + addr = __mmap_region(NULL, 0x300000, 0x3000, vma_flags, 0x300, NULL); ASSERT_EQ(addr, 0x300000); /* Map at 0x250000, length 0x3000. */ - addr = __mmap_region(NULL, 0x250000, 0x3000, - VM_READ | VM_WRITE | VM_MAYREAD | VM_MAYWRITE, - 0x250, NULL); + addr = __mmap_region(NULL, 0x250000, 0x3000, vma_flags, 0x250, NULL); ASSERT_EQ(addr, 0x250000); /* Map at 0x303000, merging to 0x300000 of length 0x6000. */ - addr = __mmap_region(NULL, 0x303000, 0x3000, - VM_READ | VM_WRITE | VM_MAYREAD | VM_MAYWRITE, - 0x303, NULL); + addr = __mmap_region(NULL, 0x303000, 0x3000, vma_flags, 0x303, NULL); ASSERT_EQ(addr, 0x303000); /* Map at 0x24d000, merging to 0x250000 of length 0x6000. */ - addr = __mmap_region(NULL, 0x24d000, 0x3000, - VM_READ | VM_WRITE | VM_MAYREAD | VM_MAYWRITE, - 0x24d, NULL); + addr = __mmap_region(NULL, 0x24d000, 0x3000, vma_flags, 0x24d, NULL); ASSERT_EQ(addr, 0x24d000); ASSERT_EQ(mm.map_count, 2); -- 2.53.0
