From 8d0920bde5eb8ec7e567939b85e65a0596c8580d Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Thu, 22 Apr 2021 12:08:20 +0200 Subject: mm: remove VM_DENYWRITE All in-tree users of MAP_DENYWRITE are gone. MAP_DENYWRITE cannot be set from user space, so all users are gone; let's remove it. Acked-by: "Eric W. Biederman" Acked-by: Christian König Signed-off-by: David Hildenbrand --- mm/mmap.c | 27 +++------------------------ 1 file changed, 3 insertions(+), 24 deletions(-) (limited to 'mm') diff --git a/mm/mmap.c b/mm/mmap.c index ca54d36d203a..589dc1dc13db 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -148,8 +148,6 @@ void vma_set_page_prot(struct vm_area_struct *vma) static void __remove_shared_vm_struct(struct vm_area_struct *vma, struct file *file, struct address_space *mapping) { - if (vma->vm_flags & VM_DENYWRITE) - allow_write_access(file); if (vma->vm_flags & VM_SHARED) mapping_unmap_writable(mapping); @@ -666,8 +664,6 @@ static void __vma_link_file(struct vm_area_struct *vma) if (file) { struct address_space *mapping = file->f_mapping; - if (vma->vm_flags & VM_DENYWRITE) - put_write_access(file_inode(file)); if (vma->vm_flags & VM_SHARED) mapping_allow_writable(mapping); @@ -1788,22 +1784,12 @@ unsigned long mmap_region(struct file *file, unsigned long addr, vma->vm_pgoff = pgoff; if (file) { - if (vm_flags & VM_DENYWRITE) { - error = deny_write_access(file); - if (error) - goto free_vma; - } if (vm_flags & VM_SHARED) { error = mapping_map_writable(file->f_mapping); if (error) - goto allow_write_and_free_vma; + goto free_vma; } - /* ->mmap() can change vma->vm_file, but must guarantee that - * vma_link() below can deny write-access if VM_DENYWRITE is set - * and map writably if VM_SHARED is set. This usually means the - * new file must not have been exposed to user-space, yet. - */ vma->vm_file = get_file(file); error = call_mmap(file, vma); if (error) @@ -1860,13 +1846,9 @@ unsigned long mmap_region(struct file *file, unsigned long addr, vma_link(mm, vma, prev, rb_link, rb_parent); /* Once vma denies write, undo our temporary denial count */ - if (file) { unmap_writable: - if (vm_flags & VM_SHARED) - mapping_unmap_writable(file->f_mapping); - if (vm_flags & VM_DENYWRITE) - allow_write_access(file); - } + if (file && vm_flags & VM_SHARED) + mapping_unmap_writable(file->f_mapping); file = vma->vm_file; out: perf_event_mmap(vma); @@ -1906,9 +1888,6 @@ unmap_and_free_vma: charged = 0; if (vm_flags & VM_SHARED) mapping_unmap_writable(file->f_mapping); -allow_write_and_free_vma: - if (vm_flags & VM_DENYWRITE) - allow_write_access(file); free_vma: vm_area_free(vma); unacct_error: -- cgit v1.2.3 From 6128b3af2a5e42386aa7faf37609b57f39fb7d00 Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Fri, 23 Apr 2021 09:38:14 +0200 Subject: mm: ignore MAP_DENYWRITE in ksys_mmap_pgoff() Let's also remove masking off MAP_DENYWRITE from ksys_mmap_pgoff(): the last in-tree occurrence of MAP_DENYWRITE is now in LEGACY_MAP_MASK, which accepts the flag e.g., for MAP_SHARED_VALIDATE; however, the flag is ignored throughout the kernel now. Add a comment to LEGACY_MAP_MASK stating that MAP_DENYWRITE is ignored. Acked-by: "Eric W. Biederman" Acked-by: Christian König Signed-off-by: David Hildenbrand --- include/linux/mman.h | 3 ++- mm/mmap.c | 2 -- mm/nommu.c | 2 -- 3 files changed, 2 insertions(+), 5 deletions(-) (limited to 'mm') diff --git a/include/linux/mman.h b/include/linux/mman.h index bd9aadda047b..b66e91b8176c 100644 --- a/include/linux/mman.h +++ b/include/linux/mman.h @@ -32,7 +32,8 @@ * The historical set of flags that all mmap implementations implicitly * support when a ->mmap_validate() op is not provided in file_operations. * - * MAP_EXECUTABLE is completely ignored throughout the kernel. + * MAP_EXECUTABLE and MAP_DENYWRITE are completely ignored throughout the + * kernel. */ #define LEGACY_MAP_MASK (MAP_SHARED \ | MAP_PRIVATE \ diff --git a/mm/mmap.c b/mm/mmap.c index 589dc1dc13db..bf11fc6e8311 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -1626,8 +1626,6 @@ unsigned long ksys_mmap_pgoff(unsigned long addr, unsigned long len, return PTR_ERR(file); } - flags &= ~MAP_DENYWRITE; - retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff); out_fput: if (file) diff --git a/mm/nommu.c b/mm/nommu.c index 3a93d4054810..0987d131bdfc 100644 --- a/mm/nommu.c +++ b/mm/nommu.c @@ -1296,8 +1296,6 @@ unsigned long ksys_mmap_pgoff(unsigned long addr, unsigned long len, goto out; } - flags &= ~MAP_DENYWRITE; - retval = vm_mmap_pgoff(file, addr, len, prot, flags, pgoff); if (file) -- cgit v1.2.3