The patch titled
revoke: break cow for private mappings
has been added to the -mm tree. Its filename is
revoke-core-code-break-cow-for-private-mappings.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: revoke: break cow for private mappings
From: Pekka Enberg <penberg@xxxxxxxxxxxxxx>
We need to break COW for private mappings to make sure a process cannot
read new data after an inode has been revoked.
Signed-off-by: Pekka Enberg <penberg@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/revoke.c | 85 ++++++++++++++++++++++++++++++++++++++++++--------
1 files changed, 73 insertions(+), 12 deletions(-)
diff -puN fs/revoke.c~revoke-core-code-break-cow-for-private-mappings fs/revoke.c
--- a/fs/revoke.c~revoke-core-code-break-cow-for-private-mappings
+++ a/fs/revoke.c
@@ -175,12 +175,58 @@ static inline bool need_revoke(struct vm
if (file->f_path.dentry->d_inode != inode)
return false;
- if (!(vma->vm_flags & VM_SHARED))
- return false;
-
return file != to_exclude;
}
+static int __revoke_break_cow(struct task_struct *tsk, struct inode *inode,
+ struct file *to_exclude)
+{
+ struct mm_struct *mm = tsk->mm;
+ struct vm_area_struct *vma;
+ int err = 0;
+
+ down_write(&mm->mmap_sem);
+ for (vma = mm->mmap; vma != NULL; vma = vma->vm_next) {
+ int ret;
+
+ if (vma->vm_flags & VM_SHARED)
+ continue;
+
+ if (!need_revoke(vma, inode, to_exclude))
+ continue;
+
+ ret = get_user_pages(tsk, tsk->mm, vma->vm_start,
+ vma->vm_end-vma->vm_start, 1, 1, NULL,
+ NULL);
+ if (ret < 0) {
+ err = ret;
+ break;
+ }
+ }
+ up_write(&mm->mmap_sem);
+ return err;
+}
+
+static int revoke_break_cow(struct revoke_table *table, struct inode *inode,
+ struct file *to_exclude)
+{
+ unsigned long i;
+ int err = 0;
+
+ for (i = 0; i < table->end; i++) {
+ struct revokefs_inode_info *info;
+ struct file *this;
+
+ this = table->files[i];
+ info = revokefs_i(this->f_dentry->d_inode);
+
+ err = __revoke_break_cow(info->owner, inode, to_exclude);
+ if (err)
+ break;
+ }
+ return err;
+}
+
/*
* LOCKING: down_write(&mm->mmap_sem)
* -> spin_lock(&mapping->i_mmap_lock)
@@ -236,6 +282,9 @@ static int revoke_mm(struct mm_struct *m
goto out;
}
for (vma = mm->mmap; vma != NULL; vma = vma->vm_next) {
+ if (!(vma->vm_flags & VM_SHARED))
+ continue;
+
if (!need_revoke(vma, mapping->host, to_exclude))
continue;
@@ -262,6 +311,9 @@ static void revoke_mapping_tree(struct a
vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, 0, ULONG_MAX) {
int err;
+ if (!(vma->vm_flags & VM_SHARED))
+ continue;
+
if (likely(!need_revoke(vma, mapping->host, to_exclude)))
continue;
@@ -381,12 +433,9 @@ static int revoke_files(struct revoke_ta
put_task_struct(info->owner);
info->owner = NULL; /* To avoid restoring closed file. */
if (err)
- goto failed;
+ goto out;
}
- return 0;
-
- failed:
- restore_files(table);
+ out:
return err;
}
@@ -528,10 +577,8 @@ static int do_revoke(struct inode *inode
exit_loop:
read_unlock(&tasklist_lock);
- if (err) {
- restore_files(table);
- goto out_free_table;
- }
+ if (err)
+ goto out_restore;
/*
* Take down shared memory mappings.
@@ -539,13 +586,27 @@ static int do_revoke(struct inode *inode
revoke_mapping(inode->i_mapping, to_exclude);
/*
+ * Break COW for private mappings.
+ */
+ err = revoke_break_cow(table, inode, to_exclude);
+ if (err)
+ goto out_restore;
+
+ /*
* Now, revoke the files for good.
*/
err = revoke_files(table);
+ if (err)
+ goto out_restore;
+
out_free_table:
free_revoke_table(table);
out:
return err;
+
+ out_restore:
+ restore_files(table);
+ goto out_free_table;
}
asmlinkage long sys_revokeat(int dfd, const char __user * filename)
_
Patches currently in -mm which might be from penberg@xxxxxxxxxxxxxx are
slab-introduce-krealloc.patch
slab-introduce-krealloc-fix.patch
unionfs-fix-slab-abuses-with-krealloc.patch
slab-ensure-cache_alloc_refill-terminates.patch
slab-use-num_possible_cpus-in-enable_cpucache.patch
slab-dont-allocate-empty-shared-caches.patch
slab-numa-kmem_cache-diet.patch
module-use-krealloc.patch
slab-use-cpu_lock_.patch
revoke-special-mmap-handling.patch
revoke-special-mmap-handling-vs-fault-vs-invalidate.patch
revoke-core-code.patch
revoke-core-code-misc-fixes.patch
revoke-core-code-fix-shared-mapping-revoke.patch
revoke-core-code-move-magic.patch
revoke-core-code-fs-revokec-cleanups-and-bugfix-for-64bit-systems.patch
revoke-core-code-revoke-no-revoke-for-nommu.patch
revoke-core-code-fix-shared-mapping-revoke-revoke-only-revoke-mappings-for-the-given-inode.patch
revoke-core-code-break-cow-for-private-mappings.patch
revoke-support-for-ext2-and-ext3.patch
revoke-add-documentation.patch
revoke-wire-up-i386-system-calls.patch
slab-leaks3-default-y.patch
-
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