diff options
Diffstat (limited to 'fs/userfaultfd.c')
| -rw-r--r-- | fs/userfaultfd.c | 39 |
1 files changed, 31 insertions, 8 deletions
diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index 356d2b8568c1..89800fc7dc9d 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -53,7 +53,7 @@ struct userfaultfd_ctx { /* a refile sequence protected by fault_pending_wqh lock */ struct seqcount refile_seq; /* pseudo fd refcounting */ - atomic_t refcount; + refcount_t refcount; /* userfaultfd syscall flags */ unsigned int flags; /* features requested from the userspace */ @@ -140,8 +140,7 @@ out: */ static void userfaultfd_ctx_get(struct userfaultfd_ctx *ctx) { - if (!atomic_inc_not_zero(&ctx->refcount)) - BUG(); + refcount_inc(&ctx->refcount); } /** @@ -154,7 +153,7 @@ static void userfaultfd_ctx_get(struct userfaultfd_ctx *ctx) */ static void userfaultfd_ctx_put(struct userfaultfd_ctx *ctx) { - if (atomic_dec_and_test(&ctx->refcount)) { + if (refcount_dec_and_test(&ctx->refcount)) { VM_BUG_ON(spin_is_locked(&ctx->fault_pending_wqh.lock)); VM_BUG_ON(waitqueue_active(&ctx->fault_pending_wqh)); VM_BUG_ON(spin_is_locked(&ctx->fault_wqh.lock)); @@ -686,7 +685,7 @@ int dup_userfaultfd(struct vm_area_struct *vma, struct list_head *fcs) return -ENOMEM; } - atomic_set(&ctx->refcount, 1); + refcount_set(&ctx->refcount, 1); ctx->flags = octx->flags; ctx->state = UFFD_STATE_RUNNING; ctx->features = octx->features; @@ -736,10 +735,18 @@ void mremap_userfaultfd_prep(struct vm_area_struct *vma, struct userfaultfd_ctx *ctx; ctx = vma->vm_userfaultfd_ctx.ctx; - if (ctx && (ctx->features & UFFD_FEATURE_EVENT_REMAP)) { + + if (!ctx) + return; + + if (ctx->features & UFFD_FEATURE_EVENT_REMAP) { vm_ctx->ctx = ctx; userfaultfd_ctx_get(ctx); WRITE_ONCE(ctx->mmap_changing, true); + } else { + /* Drop uffd context if remap feature not enabled */ + vma->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX; + vma->vm_flags &= ~(VM_UFFD_WP | VM_UFFD_MISSING); } } @@ -926,7 +933,7 @@ static inline struct userfaultfd_wait_queue *find_userfault_in( wait_queue_entry_t *wq; struct userfaultfd_wait_queue *uwq; - VM_BUG_ON(!spin_is_locked(&wqh->lock)); + lockdep_assert_held(&wqh->lock); uwq = NULL; if (!waitqueue_active(wqh)) @@ -1361,6 +1368,19 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx, ret = -EINVAL; if (!vma_can_userfault(cur)) goto out_unlock; + + /* + * UFFDIO_COPY will fill file holes even without + * PROT_WRITE. This check enforces that if this is a + * MAP_SHARED, the process has write permission to the backing + * file. If VM_MAYWRITE is set it also enforces that on a + * MAP_SHARED vma: there is no F_WRITE_SEAL and no further + * F_WRITE_SEAL can be taken until the vma is destroyed. + */ + ret = -EPERM; + if (unlikely(!(cur->vm_flags & VM_MAYWRITE))) + goto out_unlock; + /* * If this vma contains ending address, and huge pages * check alignment. @@ -1406,6 +1426,7 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx, BUG_ON(!vma_can_userfault(vma)); BUG_ON(vma->vm_userfaultfd_ctx.ctx && vma->vm_userfaultfd_ctx.ctx != ctx); + WARN_ON(!(vma->vm_flags & VM_MAYWRITE)); /* * Nothing to do: this vma is already registered into this @@ -1560,6 +1581,8 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx, if (!vma->vm_userfaultfd_ctx.ctx) goto skip; + WARN_ON(!(vma->vm_flags & VM_MAYWRITE)); + if (vma->vm_start > start) start = vma->vm_start; vma_end = min(end, vma->vm_end); @@ -1911,7 +1934,7 @@ SYSCALL_DEFINE1(userfaultfd, int, flags) if (!ctx) return -ENOMEM; - atomic_set(&ctx->refcount, 1); + refcount_set(&ctx->refcount, 1); ctx->flags = flags; ctx->features = 0; ctx->state = UFFD_STATE_WAIT_API; |