1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 2021 Benjamin Berg <benjamin@sipsolutions.net>
4 * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
5 */
6
7 #include <stddef.h>
8 #include <unistd.h>
9 #include <errno.h>
10 #include <string.h>
11 #include <sys/mman.h>
12 #include <init.h>
13 #include <as-layout.h>
14 #include <mm_id.h>
15 #include <os.h>
16 #include <ptrace_user.h>
17 #include <registers.h>
18 #include <skas.h>
19 #include <sysdep/ptrace.h>
20 #include <sysdep/stub.h>
21 #include "../internal.h"
22
23 extern char __syscall_stub_start[];
24
25 void syscall_stub_dump_error(struct mm_id *mm_idp)
26 {
27 struct stub_data *proc_data = (void *)mm_idp->stack;
28 struct stub_syscall *sc;
29
30 if (proc_data->syscall_data_len < 0 ||
31 proc_data->syscall_data_len >= ARRAY_SIZE(proc_data->syscall_data))
32 panic("Syscall data was corrupted by stub (len is: %d, expected maximum: %d)!",
33 proc_data->syscall_data_len,
34 mm_idp->syscall_data_len);
35
36 sc = &proc_data->syscall_data[proc_data->syscall_data_len];
37
38 printk(UM_KERN_ERR "%s : length = %d, last offset = %d",
39 __func__, mm_idp->syscall_data_len,
40 proc_data->syscall_data_len);
41 printk(UM_KERN_ERR "%s : stub syscall type %d failed, return value = 0x%lx\n",
42 __func__, sc->syscall, proc_data->err);
43
44 print_hex_dump(UM_KERN_ERR, " syscall data: ", 0,
45 16, 4, sc, sizeof(*sc), 0);
46 }
47
48 static inline unsigned long *check_init_stack(struct mm_id * mm_idp,
49 unsigned long *stack)
50 {
51 if (stack == NULL) {
52 stack = (unsigned long *) mm_idp->stack + 2;
53 *stack = 0;
54 }
55 return stack;
56 }
57
58 static unsigned long syscall_regs[MAX_REG_NR];
59
60 static int __init init_syscall_regs(void)
61 {
62 get_safe_registers(syscall_regs, NULL);
63
64 syscall_regs[REGS_IP_INDEX] = STUB_CODE +
65 ((unsigned long) stub_syscall_handler -
66 (unsigned long) __syscall_stub_start);
67 syscall_regs[REGS_SP_INDEX] = STUB_DATA +
68 offsetof(struct stub_data, sigstack) +
69 sizeof(((struct stub_data *) 0)->sigstack) -
70 sizeof(void *);
71
72 return 0;
73 }
74
75 __initcall(init_syscall_regs);
76
77 static inline long do_syscall_stub(struct mm_id *mm_idp)
78 {
79 struct stub_data *proc_data = (void *)mm_idp->stack;
80 int n, i;
81 int err, pid = mm_idp->u.pid;
82
83 n = ptrace_setregs(pid, syscall_regs);
84 if (n < 0) {
85 printk(UM_KERN_ERR "Registers - \n");
86 for (i = 0; i < MAX_REG_NR; i++)
87 printk(UM_KERN_ERR "\t%d\t0x%lx\n", i, syscall_regs[i]);
88 panic("%s : PTRACE_SETREGS failed, errno = %d\n",
89 __func__, -n);
90 }
91
92 /* Inform process how much we have filled in. */
93 proc_data->syscall_data_len = mm_idp->syscall_data_len;
94
95 err = ptrace(PTRACE_CONT, pid, 0, 0);
96 if (err)
97 panic("Failed to continue stub, pid = %d, errno = %d\n", pid,
98 errno);
99
100 wait_stub_done(pid);
101
102 /*
103 * proc_data->err will be non-zero if there was an (unexpected) error.
104 * In that case, syscall_data_len points to the last executed syscall,
105 * otherwise it will be zero (but we do not need to rely on that).
106 */
107 if (proc_data->err < 0) {
108 syscall_stub_dump_error(mm_idp);
109
110 /* Store error code in case someone tries to add more syscalls */
111 mm_idp->syscall_data_len = proc_data->err;
112 } else {
113 mm_idp->syscall_data_len = 0;
114 }
115
116 return mm_idp->syscall_data_len;
117 }
118
119 int syscall_stub_flush(struct mm_id *mm_idp)
120 {
121 int res;
122
123 if (mm_idp->syscall_data_len == 0)
124 return 0;
125
126 /* If an error happened already, report it and reset the state. */
127 if (mm_idp->syscall_data_len < 0) {
128 res = mm_idp->syscall_data_len;
129 mm_idp->syscall_data_len = 0;
130 return res;
131 }
132
133 res = do_syscall_stub(mm_idp);
134 mm_idp->syscall_data_len = 0;
135
136 return res;
137 }
138
139 struct stub_syscall *syscall_stub_alloc(struct mm_id *mm_idp)
140 {
141 struct stub_syscall *sc;
142 struct stub_data *proc_data = (struct stub_data *) mm_idp->stack;
143
144 if (mm_idp->syscall_data_len > 0 &&
145 mm_idp->syscall_data_len == ARRAY_SIZE(proc_data->syscall_data))
146 do_syscall_stub(mm_idp);
147
148 if (mm_idp->syscall_data_len < 0) {
149 /* Return dummy to retain error state. */
150 sc = &proc_data->syscall_data[0];
151 } else {
152 sc = &proc_data->syscall_data[mm_idp->syscall_data_len];
153 mm_idp->syscall_data_len += 1;
154 }
155 memset(sc, 0, sizeof(*sc));
156
157 return sc;
158 }
159
160 static struct stub_syscall *syscall_stub_get_previous(struct mm_id *mm_idp,
161 int syscall_type,
162 unsigned long virt)
163 {
164 if (mm_idp->syscall_data_len > 0) {
165 struct stub_data *proc_data = (void *) mm_idp->stack;
166 struct stub_syscall *sc;
167
168 sc = &proc_data->syscall_data[mm_idp->syscall_data_len - 1];
169
170 if (sc->syscall == syscall_type &&
171 sc->mem.addr + sc->mem.length == virt)
172 return sc;
173 }
174
175 return NULL;
176 }
177
178 int map(struct mm_id *mm_idp, unsigned long virt, unsigned long len, int prot,
179 int phys_fd, unsigned long long offset)
180 {
181 struct stub_syscall *sc;
182
183 /* Compress with previous syscall if that is possible */
184 sc = syscall_stub_get_previous(mm_idp, STUB_SYSCALL_MMAP, virt);
185 if (sc && sc->mem.prot == prot && sc->mem.fd == phys_fd &&
186 sc->mem.offset == MMAP_OFFSET(offset - sc->mem.length)) {
187 sc->mem.length += len;
188 return 0;
189 }
190
191 sc = syscall_stub_alloc(mm_idp);
192 sc->syscall = STUB_SYSCALL_MMAP;
193 sc->mem.addr = virt;
194 sc->mem.length = len;
195 sc->mem.prot = prot;
196 sc->mem.fd = phys_fd;
197 sc->mem.offset = MMAP_OFFSET(offset);
198
199 return 0;
200 }
201
202 int unmap(struct mm_id *mm_idp, unsigned long addr, unsigned long len)
203 {
204 struct stub_syscall *sc;
205
206 /* Compress with previous syscall if that is possible */
207 sc = syscall_stub_get_previous(mm_idp, STUB_SYSCALL_MUNMAP, addr);
208 if (sc) {
209 sc->mem.length += len;
210 return 0;
211 }
212
213 sc = syscall_stub_alloc(mm_idp);
214 sc->syscall = STUB_SYSCALL_MUNMAP;
215 sc->mem.addr = addr;
216 sc->mem.length = len;
217
218 return 0;
219 }
220
221 int protect(struct mm_id *mm_idp, unsigned long addr, unsigned long len,
222 unsigned int prot)
223 {
224 struct stub_syscall *sc;
225
226 /* Compress with previous syscall if that is possible */
227 sc = syscall_stub_get_previous(mm_idp, STUB_SYSCALL_MPROTECT, addr);
228 if (sc && sc->mem.prot == prot) {
229 sc->mem.length += len;
230 return 0;
231 }
232
233 sc = syscall_stub_alloc(mm_idp);
234 sc->syscall = STUB_SYSCALL_MPROTECT;
235 sc->mem.addr = addr;
236 sc->mem.length = len;
237 sc->mem.prot = prot;
238
239 return 0;
240 }
241
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.