/* * we do not have to muck with descriptors here, that is * done in switch_mm() as needed. */ int init_new_context(struct task_struct *tsk, struct mm_struct *mm) { struct ldt_struct *new_ldt; struct mm_struct *old_mm; int retval = 0; mutex_init(&mm->context.lock); old_mm = current->mm; if (!old_mm) { mm->context.ldt = NULL; return 0; } mutex_lock(&old_mm->context.lock); if (!old_mm->context.ldt) { mm->context.ldt = NULL; goto out_unlock; } new_ldt = alloc_ldt_struct(old_mm->context.ldt->size); if (!new_ldt) { retval = -ENOMEM; goto out_unlock; } memcpy(new_ldt->entries, old_mm->context.ldt->entries, new_ldt->size * LDT_ENTRY_SIZE); finalize_ldt_struct(new_ldt); mm->context.ldt = new_ldt; out_unlock: mutex_unlock(&old_mm->context.lock); return retval; }
/* * we do not have to muck with descriptors here, that is * done in switch_mm() as needed. */ int init_new_context(struct task_struct *tsk, struct mm_struct *mm) { struct ldt_struct *new_ldt; struct mm_struct *old_mm; int retval = 0; if (tsk == current) { mm->context.vdso = 0; #ifdef CONFIG_X86_32 #if defined(CONFIG_PAX_PAGEEXEC) || defined(CONFIG_PAX_SEGMEXEC) mm->context.user_cs_base = 0UL; mm->context.user_cs_limit = ~0UL; #if defined(CONFIG_PAX_PAGEEXEC) && defined(CONFIG_SMP) cpumask_clear(&mm->context.cpu_user_cs_mask); #endif #endif #endif } mutex_init(&mm->context.lock); old_mm = current->mm; if (!old_mm) { mm->context.ldt = NULL; return 0; } mutex_lock(&old_mm->context.lock); if (!old_mm->context.ldt) { mm->context.ldt = NULL; goto out_unlock; } new_ldt = alloc_ldt_struct(old_mm->context.ldt->size); if (!new_ldt) { retval = -ENOMEM; goto out_unlock; } memcpy(new_ldt->entries, old_mm->context.ldt->entries, new_ldt->size * LDT_ENTRY_SIZE); finalize_ldt_struct(new_ldt); mm->context.ldt = new_ldt; out_unlock: mutex_unlock(&old_mm->context.lock); return retval; }
static int write_ldt(void __user *ptr, unsigned long bytecount, int oldmode) { struct mm_struct *mm = current->mm; struct desc_struct ldt; int error; struct user_desc ldt_info; int oldsize, newsize; struct ldt_struct *new_ldt, *old_ldt; error = -EINVAL; if (bytecount != sizeof(ldt_info)) goto out; error = -EFAULT; if (copy_from_user(&ldt_info, ptr, sizeof(ldt_info))) goto out; error = -EINVAL; if (ldt_info.entry_number >= LDT_ENTRIES) goto out; if (ldt_info.contents == 3) { if (oldmode) goto out; if (ldt_info.seg_not_present == 0) goto out; } if ((oldmode && !ldt_info.base_addr && !ldt_info.limit) || LDT_empty(&ldt_info)) { /* The user wants to clear the entry. */ memset(&ldt, 0, sizeof(ldt)); } else { #ifdef CONFIG_PAX_SEGMEXEC if ((mm->pax_flags & MF_PAX_SEGMEXEC) && (ldt_info.contents & MODIFY_LDT_CONTENTS_CODE)) { error = -EINVAL; goto out; } #endif if (!IS_ENABLED(CONFIG_X86_16BIT) && !ldt_info.seg_32bit) { error = -EINVAL; goto out; } fill_ldt(&ldt, &ldt_info); if (oldmode) ldt.avl = 0; } mutex_lock(&mm->context.lock); old_ldt = mm->context.ldt; oldsize = old_ldt ? old_ldt->size : 0; newsize = max((int)(ldt_info.entry_number + 1), oldsize); error = -ENOMEM; new_ldt = alloc_ldt_struct(newsize); if (!new_ldt) goto out_unlock; if (old_ldt) memcpy(new_ldt->entries, old_ldt->entries, oldsize * LDT_ENTRY_SIZE); new_ldt->entries[ldt_info.entry_number] = ldt; finalize_ldt_struct(new_ldt); install_ldt(mm, new_ldt); free_ldt_struct(old_ldt); error = 0; out_unlock: mutex_unlock(&mm->context.lock); out: return error; }