1/*
  2 * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
  3 * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
  4 * Licensed under the GPL
  5 */
  6
  7#include <linux/mm.h>
  8#include <linux/sched/signal.h>
  9#include <linux/slab.h>
 10
 11#include <asm/pgalloc.h>
 12#include <asm/pgtable.h>
 13#include <asm/sections.h>
 14#include <as-layout.h>
 15#include <os.h>
 16#include <skas.h>
 17
 18static int init_stub_pte(struct mm_struct *mm, unsigned long proc,
 19			 unsigned long kernel)
 20{
 21	pgd_t *pgd;
 
 22	pud_t *pud;
 23	pmd_t *pmd;
 24	pte_t *pte;
 25
 26	pgd = pgd_offset(mm, proc);
 27	pud = pud_alloc(mm, pgd, proc);
 28	if (!pud)
 
 29		goto out;
 30
 
 
 
 
 31	pmd = pmd_alloc(mm, pud, proc);
 32	if (!pmd)
 33		goto out_pmd;
 34
 35	pte = pte_alloc_map(mm, pmd, proc);
 36	if (!pte)
 37		goto out_pte;
 38
 39	*pte = mk_pte(virt_to_page(kernel), __pgprot(_PAGE_PRESENT));
 40	*pte = pte_mkread(*pte);
 41	return 0;
 42
 43 out_pte:
 44	pmd_free(mm, pmd);
 45 out_pmd:
 46	pud_free(mm, pud);
 
 
 47 out:
 48	return -ENOMEM;
 49}
 50
 51int init_new_context(struct task_struct *task, struct mm_struct *mm)
 52{
 53 	struct mm_context *from_mm = NULL;
 54	struct mm_context *to_mm = &mm->context;
 55	unsigned long stack = 0;
 56	int ret = -ENOMEM;
 57
 58	stack = get_zeroed_page(GFP_KERNEL);
 59	if (stack == 0)
 60		goto out;
 61
 62	to_mm->id.stack = stack;
 63	if (current->mm != NULL && current->mm != &init_mm)
 64		from_mm = &current->mm->context;
 65
 66	block_signals();
 67	if (from_mm)
 68		to_mm->id.u.pid = copy_context_skas0(stack,
 69						     from_mm->id.u.pid);
 70	else to_mm->id.u.pid = start_userspace(stack);
 71	unblock_signals();
 72
 73	if (to_mm->id.u.pid < 0) {
 74		ret = to_mm->id.u.pid;
 75		goto out_free;
 76	}
 77
 78	ret = init_new_ldt(to_mm, from_mm);
 79	if (ret < 0) {
 80		printk(KERN_ERR "init_new_context_skas - init_ldt"
 81		       " failed, errno = %d\n", ret);
 82		goto out_free;
 83	}
 84
 85	return 0;
 86
 87 out_free:
 88	if (to_mm->id.stack != 0)
 89		free_page(to_mm->id.stack);
 90 out:
 91	return ret;
 92}
 93
 94void uml_setup_stubs(struct mm_struct *mm)
 95{
 96	int err, ret;
 97
 98	ret = init_stub_pte(mm, STUB_CODE,
 99			    (unsigned long) __syscall_stub_start);
100	if (ret)
101		goto out;
102
103	ret = init_stub_pte(mm, STUB_DATA, mm->context.id.stack);
104	if (ret)
105		goto out;
106
107	mm->context.stub_pages[0] = virt_to_page(__syscall_stub_start);
108	mm->context.stub_pages[1] = virt_to_page(mm->context.id.stack);
109
110	/* dup_mmap already holds mmap_sem */
111	err = install_special_mapping(mm, STUB_START, STUB_END - STUB_START,
112				      VM_READ | VM_MAYREAD | VM_EXEC |
113				      VM_MAYEXEC | VM_DONTCOPY | VM_PFNMAP,
114				      mm->context.stub_pages);
115	if (err) {
116		printk(KERN_ERR "install_special_mapping returned %d\n", err);
117		goto out;
118	}
119	return;
120
121out:
122	force_sigsegv(SIGSEGV, current);
123}
124
125void arch_exit_mmap(struct mm_struct *mm)
126{
127	pte_t *pte;
128
129	pte = virt_to_pte(mm, STUB_CODE);
130	if (pte != NULL)
131		pte_clear(mm, STUB_CODE, pte);
132
133	pte = virt_to_pte(mm, STUB_DATA);
134	if (pte == NULL)
135		return;
136
137	pte_clear(mm, STUB_DATA, pte);
138}
139
140void destroy_context(struct mm_struct *mm)
141{
142	struct mm_context *mmu = &mm->context;
143
144	/*
145	 * If init_new_context wasn't called, this will be
146	 * zero, resulting in a kill(0), which will result in the
147	 * whole UML suddenly dying.  Also, cover negative and
148	 * 1 cases, since they shouldn't happen either.
149	 */
150	if (mmu->id.u.pid < 2) {
151		printk(KERN_ERR "corrupt mm_context - pid = %d\n",
152		       mmu->id.u.pid);
153		return;
154	}
155	os_kill_ptraced_process(mmu->id.u.pid, 1);
156
157	free_page(mmu->id.stack);
158	free_ldt(mmu);
159}

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
  4 * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
 
  5 */
  6
  7#include <linux/mm.h>
  8#include <linux/sched/signal.h>
  9#include <linux/slab.h>
 10
 11#include <asm/pgalloc.h>
 
 12#include <asm/sections.h>
 13#include <as-layout.h>
 14#include <os.h>
 15#include <skas.h>
 16
 17static int init_stub_pte(struct mm_struct *mm, unsigned long proc,
 18			 unsigned long kernel)
 19{
 20	pgd_t *pgd;
 21	p4d_t *p4d;
 22	pud_t *pud;
 23	pmd_t *pmd;
 24	pte_t *pte;
 25
 26	pgd = pgd_offset(mm, proc);
 27
 28	p4d = p4d_alloc(mm, pgd, proc);
 29	if (!p4d)
 30		goto out;
 31
 32	pud = pud_alloc(mm, p4d, proc);
 33	if (!pud)
 34		goto out_pud;
 35
 36	pmd = pmd_alloc(mm, pud, proc);
 37	if (!pmd)
 38		goto out_pmd;
 39
 40	pte = pte_alloc_map(mm, pmd, proc);
 41	if (!pte)
 42		goto out_pte;
 43
 44	*pte = mk_pte(virt_to_page(kernel), __pgprot(_PAGE_PRESENT));
 45	*pte = pte_mkread(*pte);
 46	return 0;
 47
 48 out_pte:
 49	pmd_free(mm, pmd);
 50 out_pmd:
 51	pud_free(mm, pud);
 52 out_pud:
 53	p4d_free(mm, p4d);
 54 out:
 55	return -ENOMEM;
 56}
 57
 58int init_new_context(struct task_struct *task, struct mm_struct *mm)
 59{
 60 	struct mm_context *from_mm = NULL;
 61	struct mm_context *to_mm = &mm->context;
 62	unsigned long stack = 0;
 63	int ret = -ENOMEM;
 64
 65	stack = get_zeroed_page(GFP_KERNEL);
 66	if (stack == 0)
 67		goto out;
 68
 69	to_mm->id.stack = stack;
 70	if (current->mm != NULL && current->mm != &init_mm)
 71		from_mm = &current->mm->context;
 72
 73	block_signals_trace();
 74	if (from_mm)
 75		to_mm->id.u.pid = copy_context_skas0(stack,
 76						     from_mm->id.u.pid);
 77	else to_mm->id.u.pid = start_userspace(stack);
 78	unblock_signals_trace();
 79
 80	if (to_mm->id.u.pid < 0) {
 81		ret = to_mm->id.u.pid;
 82		goto out_free;
 83	}
 84
 85	ret = init_new_ldt(to_mm, from_mm);
 86	if (ret < 0) {
 87		printk(KERN_ERR "init_new_context_skas - init_ldt"
 88		       " failed, errno = %d\n", ret);
 89		goto out_free;
 90	}
 91
 92	return 0;
 93
 94 out_free:
 95	if (to_mm->id.stack != 0)
 96		free_page(to_mm->id.stack);
 97 out:
 98	return ret;
 99}
100
101void uml_setup_stubs(struct mm_struct *mm)
102{
103	int err, ret;
104
105	ret = init_stub_pte(mm, STUB_CODE,
106			    (unsigned long) __syscall_stub_start);
107	if (ret)
108		goto out;
109
110	ret = init_stub_pte(mm, STUB_DATA, mm->context.id.stack);
111	if (ret)
112		goto out;
113
114	mm->context.stub_pages[0] = virt_to_page(__syscall_stub_start);
115	mm->context.stub_pages[1] = virt_to_page(mm->context.id.stack);
116
117	/* dup_mmap already holds mmap_lock */
118	err = install_special_mapping(mm, STUB_START, STUB_END - STUB_START,
119				      VM_READ | VM_MAYREAD | VM_EXEC |
120				      VM_MAYEXEC | VM_DONTCOPY | VM_PFNMAP,
121				      mm->context.stub_pages);
122	if (err) {
123		printk(KERN_ERR "install_special_mapping returned %d\n", err);
124		goto out;
125	}
126	return;
127
128out:
129	force_sigsegv(SIGSEGV);
130}
131
132void arch_exit_mmap(struct mm_struct *mm)
133{
134	pte_t *pte;
135
136	pte = virt_to_pte(mm, STUB_CODE);
137	if (pte != NULL)
138		pte_clear(mm, STUB_CODE, pte);
139
140	pte = virt_to_pte(mm, STUB_DATA);
141	if (pte == NULL)
142		return;
143
144	pte_clear(mm, STUB_DATA, pte);
145}
146
147void destroy_context(struct mm_struct *mm)
148{
149	struct mm_context *mmu = &mm->context;
150
151	/*
152	 * If init_new_context wasn't called, this will be
153	 * zero, resulting in a kill(0), which will result in the
154	 * whole UML suddenly dying.  Also, cover negative and
155	 * 1 cases, since they shouldn't happen either.
156	 */
157	if (mmu->id.u.pid < 2) {
158		printk(KERN_ERR "corrupt mm_context - pid = %d\n",
159		       mmu->id.u.pid);
160		return;
161	}
162	os_kill_ptraced_process(mmu->id.u.pid, 1);
163
164	free_page(mmu->id.stack);
165	free_ldt(mmu);
166}