diff options
Diffstat (limited to 'mm/shmem.c')
| -rw-r--r-- | mm/shmem.c | 42 |
1 files changed, 34 insertions, 8 deletions
diff --git a/mm/shmem.c b/mm/shmem.c index 69106c600692..67d9f809ed01 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -2149,6 +2149,25 @@ out_nomem: static int shmem_mmap(struct file *file, struct vm_area_struct *vma) { + struct shmem_inode_info *info = SHMEM_I(file_inode(file)); + + + if (info->seals & F_SEAL_FUTURE_WRITE) { + /* + * New PROT_WRITE and MAP_SHARED mmaps are not allowed when + * "future write" seal active. + */ + if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_WRITE)) + return -EPERM; + + /* + * Since the F_SEAL_FUTURE_WRITE seals allow for a MAP_SHARED + * read-only mapping, take care to not allow mprotect to revert + * protections. + */ + vma->vm_flags &= ~(VM_MAYWRITE); + } + file_accessed(file); vma->vm_ops = &shmem_vm_ops; if (IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE) && @@ -2402,8 +2421,9 @@ shmem_write_begin(struct file *file, struct address_space *mapping, pgoff_t index = pos >> PAGE_SHIFT; /* i_mutex is held by caller */ - if (unlikely(info->seals & (F_SEAL_WRITE | F_SEAL_GROW))) { - if (info->seals & F_SEAL_WRITE) + if (unlikely(info->seals & (F_SEAL_GROW | + F_SEAL_WRITE | F_SEAL_FUTURE_WRITE))) { + if (info->seals & (F_SEAL_WRITE | F_SEAL_FUTURE_WRITE)) return -EPERM; if ((info->seals & F_SEAL_GROW) && pos + len > inode->i_size) return -EPERM; @@ -2762,7 +2782,8 @@ continue_resched: #define F_ALL_SEALS (F_SEAL_SEAL | \ F_SEAL_SHRINK | \ F_SEAL_GROW | \ - F_SEAL_WRITE) + F_SEAL_WRITE | \ + F_SEAL_FUTURE_WRITE) int shmem_add_seals(struct file *file, unsigned int seals) { @@ -2889,7 +2910,7 @@ static long shmem_fallocate(struct file *file, int mode, loff_t offset, DECLARE_WAIT_QUEUE_HEAD_ONSTACK(shmem_falloc_waitq); /* protected by i_mutex */ - if (info->seals & F_SEAL_WRITE) { + if (info->seals & (F_SEAL_WRITE | F_SEAL_FUTURE_WRITE)) { error = -EPERM; goto out; } @@ -4312,6 +4333,14 @@ struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags } EXPORT_SYMBOL_GPL(shmem_file_setup); +void shmem_set_file(struct vm_area_struct *vma, struct file *file) +{ + if (vma->vm_file) + fput(vma->vm_file); + vma->vm_file = file; + vma->vm_ops = &shmem_vm_ops; +} + /** * shmem_zero_setup - setup a shared anonymous mapping * @vma: the vma to be mmapped is prepared by do_mmap_pgoff @@ -4331,10 +4360,7 @@ int shmem_zero_setup(struct vm_area_struct *vma) if (IS_ERR(file)) return PTR_ERR(file); - if (vma->vm_file) - fput(vma->vm_file); - vma->vm_file = file; - vma->vm_ops = &shmem_vm_ops; + shmem_set_file(vma, file); if (IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE) && ((vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK) < |