Commit | Line | Data |
---|---|---|
1da177e4 | 1 | /* |
1da177e4 LT |
2 | * Copyright (C) 2001 Andrea Arcangeli <andrea@suse.de> SuSE |
3 | * Copyright 2003 Andi Kleen, SuSE Labs. | |
4 | * | |
5cec93c2 AL |
5 | * [ NOTE: this mechanism is now deprecated in favor of the vDSO. ] |
6 | * | |
1da177e4 LT |
7 | * Thanks to hpa@transmeta.com for some useful hint. |
8 | * Special thanks to Ingo Molnar for his early experience with | |
9 | * a different vsyscall implementation for Linux/IA32 and for the name. | |
10 | * | |
11 | * vsyscall 1 is located at -10Mbyte, vsyscall 2 is located | |
12 | * at virtual address -10Mbyte+1024bytes etc... There are at max 4 | |
13 | * vsyscalls. One vsyscall can reserve more than 1 slot to avoid | |
14 | * jumping out of line if necessary. We cannot add more with this | |
15 | * mechanism because older kernels won't return -ENOSYS. | |
1da177e4 | 16 | * |
5cec93c2 AL |
17 | * Note: the concept clashes with user mode linux. UML users should |
18 | * use the vDSO. | |
1da177e4 LT |
19 | */ |
20 | ||
21 | #include <linux/time.h> | |
22 | #include <linux/init.h> | |
23 | #include <linux/kernel.h> | |
24 | #include <linux/timer.h> | |
25 | #include <linux/seqlock.h> | |
26 | #include <linux/jiffies.h> | |
27 | #include <linux/sysctl.h> | |
29574022 | 28 | #include <linux/topology.h> |
7460ed28 | 29 | #include <linux/clocksource.h> |
c08c8205 | 30 | #include <linux/getcpu.h> |
8c131af1 AK |
31 | #include <linux/cpu.h> |
32 | #include <linux/smp.h> | |
33 | #include <linux/notifier.h> | |
5cec93c2 AL |
34 | #include <linux/syscalls.h> |
35 | #include <linux/ratelimit.h> | |
1da177e4 LT |
36 | |
37 | #include <asm/vsyscall.h> | |
38 | #include <asm/pgtable.h> | |
c9712944 | 39 | #include <asm/compat.h> |
1da177e4 | 40 | #include <asm/page.h> |
7460ed28 | 41 | #include <asm/unistd.h> |
1da177e4 LT |
42 | #include <asm/fixmap.h> |
43 | #include <asm/errno.h> | |
44 | #include <asm/io.h> | |
c08c8205 VP |
45 | #include <asm/segment.h> |
46 | #include <asm/desc.h> | |
47 | #include <asm/topology.h> | |
2aae950b | 48 | #include <asm/vgtod.h> |
5cec93c2 | 49 | #include <asm/traps.h> |
1da177e4 | 50 | |
c149a665 AL |
51 | #define CREATE_TRACE_POINTS |
52 | #include "vsyscall_trace.h" | |
53 | ||
8c49d9a7 AL |
54 | DEFINE_VVAR(int, vgetcpu_mode); |
55 | DEFINE_VVAR(struct vsyscall_gtod_data, vsyscall_gtod_data) = | |
1da177e4 | 56 | { |
c4dbe54e | 57 | .lock = __SEQLOCK_UNLOCKED(__vsyscall_gtod_data.lock), |
7460ed28 | 58 | }; |
1da177e4 | 59 | |
2b666859 | 60 | static enum { EMULATE, NATIVE, NONE } vsyscall_mode = NATIVE; |
3ae36655 AL |
61 | |
62 | static int __init vsyscall_setup(char *str) | |
63 | { | |
64 | if (str) { | |
65 | if (!strcmp("emulate", str)) | |
66 | vsyscall_mode = EMULATE; | |
67 | else if (!strcmp("native", str)) | |
68 | vsyscall_mode = NATIVE; | |
69 | else if (!strcmp("none", str)) | |
70 | vsyscall_mode = NONE; | |
71 | else | |
72 | return -EINVAL; | |
73 | ||
74 | return 0; | |
75 | } | |
76 | ||
77 | return -EINVAL; | |
78 | } | |
79 | early_param("vsyscall", vsyscall_setup); | |
80 | ||
2c622148 TB |
81 | void update_vsyscall_tz(void) |
82 | { | |
83 | unsigned long flags; | |
84 | ||
85 | write_seqlock_irqsave(&vsyscall_gtod_data.lock, flags); | |
86 | /* sys_tz has changed */ | |
87 | vsyscall_gtod_data.sys_tz = sys_tz; | |
88 | write_sequnlock_irqrestore(&vsyscall_gtod_data.lock, flags); | |
89 | } | |
90 | ||
7615856e JS |
91 | void update_vsyscall(struct timespec *wall_time, struct timespec *wtm, |
92 | struct clocksource *clock, u32 mult) | |
1da177e4 | 93 | { |
7460ed28 | 94 | unsigned long flags; |
1da177e4 | 95 | |
7460ed28 | 96 | write_seqlock_irqsave(&vsyscall_gtod_data.lock, flags); |
5cec93c2 | 97 | |
7460ed28 | 98 | /* copy vsyscall data */ |
98d0ac38 | 99 | vsyscall_gtod_data.clock.vclock_mode = clock->archdata.vclock_mode; |
5cec93c2 AL |
100 | vsyscall_gtod_data.clock.cycle_last = clock->cycle_last; |
101 | vsyscall_gtod_data.clock.mask = clock->mask; | |
102 | vsyscall_gtod_data.clock.mult = mult; | |
103 | vsyscall_gtod_data.clock.shift = clock->shift; | |
104 | vsyscall_gtod_data.wall_time_sec = wall_time->tv_sec; | |
105 | vsyscall_gtod_data.wall_time_nsec = wall_time->tv_nsec; | |
106 | vsyscall_gtod_data.wall_to_monotonic = *wtm; | |
107 | vsyscall_gtod_data.wall_time_coarse = __current_kernel_time(); | |
108 | ||
7460ed28 | 109 | write_sequnlock_irqrestore(&vsyscall_gtod_data.lock, flags); |
1da177e4 LT |
110 | } |
111 | ||
5cec93c2 AL |
112 | static void warn_bad_vsyscall(const char *level, struct pt_regs *regs, |
113 | const char *message) | |
1da177e4 | 114 | { |
5cec93c2 AL |
115 | static DEFINE_RATELIMIT_STATE(rs, DEFAULT_RATELIMIT_INTERVAL, DEFAULT_RATELIMIT_BURST); |
116 | struct task_struct *tsk; | |
1da177e4 | 117 | |
5cec93c2 AL |
118 | if (!show_unhandled_signals || !__ratelimit(&rs)) |
119 | return; | |
1da177e4 | 120 | |
5cec93c2 | 121 | tsk = current; |
7460ed28 | 122 | |
c9712944 | 123 | printk("%s%s[%d] %s ip:%lx cs:%lx sp:%lx ax:%lx si:%lx di:%lx\n", |
5cec93c2 | 124 | level, tsk->comm, task_pid_nr(tsk), |
3ae36655 | 125 | message, regs->ip, regs->cs, |
c9712944 AL |
126 | regs->sp, regs->ax, regs->si, regs->di); |
127 | } | |
128 | ||
129 | static int addr_to_vsyscall_nr(unsigned long addr) | |
130 | { | |
131 | int nr; | |
132 | ||
133 | if ((addr & ~0xC00UL) != VSYSCALL_START) | |
134 | return -EINVAL; | |
135 | ||
136 | nr = (addr & 0xC00UL) >> 10; | |
137 | if (nr >= 3) | |
138 | return -EINVAL; | |
139 | ||
140 | return nr; | |
1da177e4 LT |
141 | } |
142 | ||
4fc34901 AL |
143 | static bool write_ok_or_segv(unsigned long ptr, size_t size) |
144 | { | |
145 | /* | |
146 | * XXX: if access_ok, get_user, and put_user handled | |
147 | * sig_on_uaccess_error, this could go away. | |
148 | */ | |
149 | ||
150 | if (!access_ok(VERIFY_WRITE, (void __user *)ptr, size)) { | |
151 | siginfo_t info; | |
152 | struct thread_struct *thread = ¤t->thread; | |
153 | ||
154 | thread->error_code = 6; /* user fault, no page, write */ | |
155 | thread->cr2 = ptr; | |
156 | thread->trap_no = 14; | |
157 | ||
158 | memset(&info, 0, sizeof(info)); | |
159 | info.si_signo = SIGSEGV; | |
160 | info.si_errno = 0; | |
161 | info.si_code = SEGV_MAPERR; | |
162 | info.si_addr = (void __user *)ptr; | |
163 | ||
164 | force_sig_info(SIGSEGV, &info, current); | |
165 | return false; | |
166 | } else { | |
167 | return true; | |
168 | } | |
169 | } | |
170 | ||
3ae36655 | 171 | bool emulate_vsyscall(struct pt_regs *regs, unsigned long address) |
1da177e4 | 172 | { |
5cec93c2 AL |
173 | struct task_struct *tsk; |
174 | unsigned long caller; | |
175 | int vsyscall_nr; | |
4fc34901 | 176 | int prev_sig_on_uaccess_error; |
5cec93c2 AL |
177 | long ret; |
178 | ||
3ae36655 AL |
179 | /* |
180 | * No point in checking CS -- the only way to get here is a user mode | |
181 | * trap to a high address, which means that we're in 64-bit user code. | |
182 | */ | |
5cec93c2 | 183 | |
3ae36655 | 184 | WARN_ON_ONCE(address != regs->ip); |
c9712944 | 185 | |
3ae36655 AL |
186 | if (vsyscall_mode == NONE) { |
187 | warn_bad_vsyscall(KERN_INFO, regs, | |
188 | "vsyscall attempted with vsyscall=none"); | |
189 | return false; | |
c9712944 AL |
190 | } |
191 | ||
3ae36655 | 192 | vsyscall_nr = addr_to_vsyscall_nr(address); |
c149a665 AL |
193 | |
194 | trace_emulate_vsyscall(vsyscall_nr); | |
195 | ||
c9712944 AL |
196 | if (vsyscall_nr < 0) { |
197 | warn_bad_vsyscall(KERN_WARNING, regs, | |
3ae36655 | 198 | "misaligned vsyscall (exploit attempt or buggy program) -- look up the vsyscall kernel parameter if you need a workaround"); |
5cec93c2 AL |
199 | goto sigsegv; |
200 | } | |
d0aff6e6 | 201 | |
5cec93c2 | 202 | if (get_user(caller, (unsigned long __user *)regs->sp) != 0) { |
3ae36655 AL |
203 | warn_bad_vsyscall(KERN_WARNING, regs, |
204 | "vsyscall with bad stack (exploit attempt?)"); | |
5cec93c2 AL |
205 | goto sigsegv; |
206 | } | |
8c73626a | 207 | |
5cec93c2 AL |
208 | tsk = current; |
209 | if (seccomp_mode(&tsk->seccomp)) | |
210 | do_exit(SIGKILL); | |
211 | ||
4fc34901 AL |
212 | /* |
213 | * With a real vsyscall, page faults cause SIGSEGV. We want to | |
214 | * preserve that behavior to make writing exploits harder. | |
215 | */ | |
216 | prev_sig_on_uaccess_error = current_thread_info()->sig_on_uaccess_error; | |
217 | current_thread_info()->sig_on_uaccess_error = 1; | |
218 | ||
219 | /* | |
220 | * 0 is a valid user pointer (in the access_ok sense) on 32-bit and | |
221 | * 64-bit, so we don't need to special-case it here. For all the | |
222 | * vsyscalls, 0 means "don't write anything" not "write it at | |
223 | * address 0". | |
224 | */ | |
225 | ret = -EFAULT; | |
5cec93c2 AL |
226 | switch (vsyscall_nr) { |
227 | case 0: | |
4fc34901 AL |
228 | if (!write_ok_or_segv(regs->di, sizeof(struct timeval)) || |
229 | !write_ok_or_segv(regs->si, sizeof(struct timezone))) | |
230 | break; | |
231 | ||
5cec93c2 AL |
232 | ret = sys_gettimeofday( |
233 | (struct timeval __user *)regs->di, | |
234 | (struct timezone __user *)regs->si); | |
235 | break; | |
236 | ||
237 | case 1: | |
4fc34901 AL |
238 | if (!write_ok_or_segv(regs->di, sizeof(time_t))) |
239 | break; | |
240 | ||
5cec93c2 AL |
241 | ret = sys_time((time_t __user *)regs->di); |
242 | break; | |
243 | ||
244 | case 2: | |
4fc34901 AL |
245 | if (!write_ok_or_segv(regs->di, sizeof(unsigned)) || |
246 | !write_ok_or_segv(regs->si, sizeof(unsigned))) | |
247 | break; | |
248 | ||
5cec93c2 AL |
249 | ret = sys_getcpu((unsigned __user *)regs->di, |
250 | (unsigned __user *)regs->si, | |
251 | 0); | |
252 | break; | |
5cec93c2 | 253 | } |
8c73626a | 254 | |
4fc34901 AL |
255 | current_thread_info()->sig_on_uaccess_error = prev_sig_on_uaccess_error; |
256 | ||
5cec93c2 | 257 | if (ret == -EFAULT) { |
4fc34901 | 258 | /* Bad news -- userspace fed a bad pointer to a vsyscall. */ |
5cec93c2 AL |
259 | warn_bad_vsyscall(KERN_INFO, regs, |
260 | "vsyscall fault (exploit attempt?)"); | |
4fc34901 AL |
261 | |
262 | /* | |
263 | * If we failed to generate a signal for any reason, | |
264 | * generate one here. (This should be impossible.) | |
265 | */ | |
266 | if (WARN_ON_ONCE(!sigismember(&tsk->pending.signal, SIGBUS) && | |
267 | !sigismember(&tsk->pending.signal, SIGSEGV))) | |
268 | goto sigsegv; | |
269 | ||
270 | return true; /* Don't emulate the ret. */ | |
5cec93c2 | 271 | } |
8c73626a | 272 | |
5cec93c2 | 273 | regs->ax = ret; |
1da177e4 | 274 | |
5cec93c2 AL |
275 | /* Emulate a ret instruction. */ |
276 | regs->ip = caller; | |
277 | regs->sp += 8; | |
c08c8205 | 278 | |
3ae36655 | 279 | return true; |
5cec93c2 AL |
280 | |
281 | sigsegv: | |
5cec93c2 | 282 | force_sig(SIGSEGV, current); |
3ae36655 | 283 | return true; |
1da177e4 LT |
284 | } |
285 | ||
5cec93c2 AL |
286 | /* |
287 | * Assume __initcall executes before all user space. Hopefully kmod | |
288 | * doesn't violate that. We'll find out if it does. | |
289 | */ | |
8c131af1 | 290 | static void __cpuinit vsyscall_set_cpu(int cpu) |
c08c8205 | 291 | { |
fc8b8a60 | 292 | unsigned long d; |
c08c8205 VP |
293 | unsigned long node = 0; |
294 | #ifdef CONFIG_NUMA | |
98c9e27a | 295 | node = cpu_to_node(cpu); |
c08c8205 | 296 | #endif |
92cb7612 | 297 | if (cpu_has(&cpu_data(cpu), X86_FEATURE_RDTSCP)) |
8c131af1 | 298 | write_rdtscp_aux((node << 12) | cpu); |
c08c8205 | 299 | |
5cec93c2 AL |
300 | /* |
301 | * Store cpu number in limit so that it can be loaded quickly | |
302 | * in user space in vgetcpu. (12 bits for the CPU and 8 bits for the node) | |
303 | */ | |
fc8b8a60 JF |
304 | d = 0x0f40000000000ULL; |
305 | d |= cpu; | |
306 | d |= (node & 0xf) << 12; | |
307 | d |= (node >> 4) << 48; | |
5cec93c2 | 308 | |
fc8b8a60 | 309 | write_gdt_entry(get_cpu_gdt_table(cpu), GDT_ENTRY_PER_CPU, &d, DESCTYPE_S); |
c08c8205 VP |
310 | } |
311 | ||
8c131af1 AK |
312 | static void __cpuinit cpu_vsyscall_init(void *arg) |
313 | { | |
314 | /* preemption should be already off */ | |
315 | vsyscall_set_cpu(raw_smp_processor_id()); | |
316 | } | |
317 | ||
318 | static int __cpuinit | |
319 | cpu_vsyscall_notifier(struct notifier_block *n, unsigned long action, void *arg) | |
320 | { | |
321 | long cpu = (long)arg; | |
5cec93c2 | 322 | |
8bb78442 | 323 | if (action == CPU_ONLINE || action == CPU_ONLINE_FROZEN) |
8691e5a8 | 324 | smp_call_function_single(cpu, cpu_vsyscall_init, NULL, 1); |
5cec93c2 | 325 | |
8c131af1 AK |
326 | return NOTIFY_DONE; |
327 | } | |
328 | ||
e4026440 | 329 | void __init map_vsyscall(void) |
1da177e4 | 330 | { |
3ae36655 AL |
331 | extern char __vsyscall_page; |
332 | unsigned long physaddr_vsyscall = __pa_symbol(&__vsyscall_page); | |
9fd67b4e AL |
333 | extern char __vvar_page; |
334 | unsigned long physaddr_vvar_page = __pa_symbol(&__vvar_page); | |
1da177e4 | 335 | |
3ae36655 AL |
336 | __set_fixmap(VSYSCALL_FIRST_PAGE, physaddr_vsyscall, |
337 | vsyscall_mode == NATIVE | |
338 | ? PAGE_KERNEL_VSYSCALL | |
339 | : PAGE_KERNEL_VVAR); | |
340 | BUILD_BUG_ON((unsigned long)__fix_to_virt(VSYSCALL_FIRST_PAGE) != | |
341 | (unsigned long)VSYSCALL_START); | |
342 | ||
9fd67b4e | 343 | __set_fixmap(VVAR_PAGE, physaddr_vvar_page, PAGE_KERNEL_VVAR); |
3ae36655 AL |
344 | BUILD_BUG_ON((unsigned long)__fix_to_virt(VVAR_PAGE) != |
345 | (unsigned long)VVAR_ADDRESS); | |
1da177e4 LT |
346 | } |
347 | ||
348 | static int __init vsyscall_init(void) | |
349 | { | |
5cec93c2 AL |
350 | BUG_ON(VSYSCALL_ADDR(0) != __fix_to_virt(VSYSCALL_FIRST_PAGE)); |
351 | ||
15c8b6c1 | 352 | on_each_cpu(cpu_vsyscall_init, NULL, 1); |
be43f83d SY |
353 | /* notifier priority > KVM */ |
354 | hotcpu_notifier(cpu_vsyscall_notifier, 30); | |
5cec93c2 | 355 | |
1da177e4 LT |
356 | return 0; |
357 | } | |
1da177e4 | 358 | __initcall(vsyscall_init); |