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author | Linus Torvalds <torvalds@linux-foundation.org> | 2021-09-04 11:35:47 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-09-04 11:35:47 -0700 |
commit | 49624efa65ac9889f4e7c7b2452b2e6ce42ba37d (patch) | |
tree | 2ff7f446bf5d8459efc05d8a90d391a7e0452e92 /mm/mmap.c | |
parent | f7464060f7ab9a2424428008f0ee9f1e267e410f (diff) | |
parent | 592ca09be8333bd226f50100328a905bfc377133 (diff) | |
download | linux-49624efa65ac9889f4e7c7b2452b2e6ce42ba37d.tar.bz2 |
Merge tag 'denywrite-for-5.15' of git://github.com/davidhildenbrand/linux
Pull MAP_DENYWRITE removal from David Hildenbrand:
"Remove all in-tree usage of MAP_DENYWRITE from the kernel and remove
VM_DENYWRITE.
There are some (minor) user-visible changes:
- We no longer deny write access to shared libaries loaded via legacy
uselib(); this behavior matches modern user space e.g. dlopen().
- We no longer deny write access to the elf interpreter after exec
completed, treating it just like shared libraries (which it often
is).
- We always deny write access to the file linked via /proc/pid/exe:
sys_prctl(PR_SET_MM_MAP/EXE_FILE) will fail if write access to the
file cannot be denied, and write access to the file will remain
denied until the link is effectivel gone (exec, termination,
sys_prctl(PR_SET_MM_MAP/EXE_FILE)) -- just as if exec'ing the file.
Cross-compiled for a bunch of architectures (alpha, microblaze, i386,
s390x, ...) and verified via ltp that especially the relevant tests
(i.e., creat07 and execve04) continue working as expected"
* tag 'denywrite-for-5.15' of git://github.com/davidhildenbrand/linux:
fs: update documentation of get_write_access() and friends
mm: ignore MAP_DENYWRITE in ksys_mmap_pgoff()
mm: remove VM_DENYWRITE
binfmt: remove in-tree usage of MAP_DENYWRITE
kernel/fork: always deny write access to current MM exe_file
kernel/fork: factor out replacing the current MM exe_file
binfmt: don't use MAP_DENYWRITE when loading shared libraries via uselib()
Diffstat (limited to 'mm/mmap.c')
-rw-r--r-- | mm/mmap.c | 29 |
1 files changed, 3 insertions, 26 deletions
diff --git a/mm/mmap.c b/mm/mmap.c index dce46105e3df..88dcc5c25225 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); @@ -667,8 +665,6 @@ 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); @@ -1625,8 +1621,6 @@ 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) @@ -1783,22 +1777,12 @@ 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) @@ -1855,13 +1839,9 @@ 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); @@ -1901,9 +1881,6 @@ 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: |