void free_task(struct task_struct *tsk)
{
+ release_user_cpus_ptr(tsk);
scs_release(tsk);
#ifndef CONFIG_THREAD_INFO_IN_TASK
}
EXPORT_SYMBOL(free_task);
+static void dup_mm_exe_file(struct mm_struct *mm, struct mm_struct *oldmm)
+{
+ struct file *exe_file;
+
+ exe_file = get_mm_exe_file(oldmm);
+ RCU_INIT_POINTER(mm->exe_file, exe_file);
+ /*
+ * We depend on the oldmm having properly denied write access to the
+ * exe_file already.
+ */
+ if (exe_file && deny_write_access(exe_file))
+ pr_warn_once("deny_write_access() failed in %s\n", __func__);
+}
+
#ifdef CONFIG_MMU
static __latent_entropy int dup_mmap(struct mm_struct *mm,
struct mm_struct *oldmm)
mmap_write_lock_nested(mm, SINGLE_DEPTH_NESTING);
/* No ordering required: file already has been exposed. */
- RCU_INIT_POINTER(mm->exe_file, get_mm_exe_file(oldmm));
+ dup_mm_exe_file(mm, oldmm);
mm->total_vm = oldmm->total_vm;
mm->data_vm = oldmm->data_vm;
tmp->vm_flags &= ~(VM_LOCKED | VM_LOCKONFAULT);
file = tmp->vm_file;
if (file) {
- struct inode *inode = file_inode(file);
struct address_space *mapping = file->f_mapping;
get_file(file);
- if (tmp->vm_flags & VM_DENYWRITE)
- put_write_access(inode);
i_mmap_lock_write(mapping);
if (tmp->vm_flags & VM_SHARED)
mapping_allow_writable(mapping);
static int dup_mmap(struct mm_struct *mm, struct mm_struct *oldmm)
{
mmap_write_lock(oldmm);
- RCU_INIT_POINTER(mm->exe_file, get_mm_exe_file(oldmm));
+ dup_mm_exe_file(mm, oldmm);
mmap_write_unlock(oldmm);
return 0;
}
#endif
if (orig->cpus_ptr == &orig->cpus_mask)
tsk->cpus_ptr = &tsk->cpus_mask;
+ dup_user_cpus_ptr(tsk, orig, node);
/*
* One for the user space visible state that goes away when reaped.
*
* Main users are mmput() and sys_execve(). Callers prevent concurrent
* invocations: in mmput() nobody alive left, in execve task is single
- * threaded. sys_prctl(PR_SET_MM_MAP/EXE_FILE) also needs to set the
- * mm->exe_file, but does so without using set_mm_exe_file() in order
- * to avoid the need for any locks.
+ * threaded.
+ *
+ * Can only fail if new_exe_file != NULL.
*/
-void set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
+int set_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
{
struct file *old_exe_file;
*/
old_exe_file = rcu_dereference_raw(mm->exe_file);
- if (new_exe_file)
+ if (new_exe_file) {
+ /*
+ * We expect the caller (i.e., sys_execve) to already denied
+ * write access, so this is unlikely to fail.
+ */
+ if (unlikely(deny_write_access(new_exe_file)))
+ return -EACCES;
get_file(new_exe_file);
+ }
rcu_assign_pointer(mm->exe_file, new_exe_file);
- if (old_exe_file)
+ if (old_exe_file) {
+ allow_write_access(old_exe_file);
fput(old_exe_file);
+ }
+ return 0;
+}
+
+/**
+ * replace_mm_exe_file - replace a reference to the mm's executable file
+ *
+ * This changes mm's executable file (shown as symlink /proc/[pid]/exe),
+ * dealing with concurrent invocation and without grabbing the mmap lock in
+ * write mode.
+ *
+ * Main user is sys_prctl(PR_SET_MM_MAP/EXE_FILE).
+ */
+int replace_mm_exe_file(struct mm_struct *mm, struct file *new_exe_file)
+{
+ struct vm_area_struct *vma;
+ struct file *old_exe_file;
+ int ret = 0;
+
+ /* Forbid mm->exe_file change if old file still mapped. */
+ old_exe_file = get_mm_exe_file(mm);
+ if (old_exe_file) {
+ mmap_read_lock(mm);
+ for (vma = mm->mmap; vma && !ret; vma = vma->vm_next) {
+ if (!vma->vm_file)
+ continue;
+ if (path_equal(&vma->vm_file->f_path,
+ &old_exe_file->f_path))
+ ret = -EBUSY;
+ }
+ mmap_read_unlock(mm);
+ fput(old_exe_file);
+ if (ret)
+ return ret;
+ }
+
+ /* set the new file, lockless */
+ ret = deny_write_access(new_exe_file);
+ if (ret)
+ return -EACCES;
+ get_file(new_exe_file);
+
+ old_exe_file = xchg(&mm->exe_file, new_exe_file);
+ if (old_exe_file) {
+ /*
+ * Don't race with dup_mmap() getting the file and disallowing
+ * write access while someone might open the file writable.
+ */
+ mmap_read_lock(mm);
+ allow_write_access(old_exe_file);
+ fput(old_exe_file);
+ mmap_read_unlock(mm);
+ }
+ return 0;
}
/**
#endif
#ifdef CONFIG_BPF_SYSCALL
RCU_INIT_POINTER(p->bpf_storage, NULL);
+ p->bpf_ctx = NULL;
#endif
/* Perform scheduler related setup. Assign this task to a CPU. */
projects / linux-2.6-microblaze.git / blobdiff