Root/
1 | /*P:100 |
2 | * This is the Launcher code, a simple program which lays out the "physical" |
3 | * memory for the new Guest by mapping the kernel image and the virtual |
4 | * devices, then opens /dev/lguest to tell the kernel about the Guest and |
5 | * control it. |
6 | :*/ |
7 | #define _LARGEFILE64_SOURCE |
8 | #define _GNU_SOURCE |
9 | #include <stdio.h> |
10 | #include <string.h> |
11 | #include <unistd.h> |
12 | #include <err.h> |
13 | #include <stdint.h> |
14 | #include <stdlib.h> |
15 | #include <elf.h> |
16 | #include <sys/mman.h> |
17 | #include <sys/param.h> |
18 | #include <sys/types.h> |
19 | #include <sys/stat.h> |
20 | #include <sys/wait.h> |
21 | #include <sys/eventfd.h> |
22 | #include <fcntl.h> |
23 | #include <stdbool.h> |
24 | #include <errno.h> |
25 | #include <ctype.h> |
26 | #include <sys/socket.h> |
27 | #include <sys/ioctl.h> |
28 | #include <sys/time.h> |
29 | #include <time.h> |
30 | #include <netinet/in.h> |
31 | #include <net/if.h> |
32 | #include <linux/sockios.h> |
33 | #include <linux/if_tun.h> |
34 | #include <sys/uio.h> |
35 | #include <termios.h> |
36 | #include <getopt.h> |
37 | #include <assert.h> |
38 | #include <sched.h> |
39 | #include <limits.h> |
40 | #include <stddef.h> |
41 | #include <signal.h> |
42 | #include <pwd.h> |
43 | #include <grp.h> |
44 | |
45 | #include <linux/virtio_config.h> |
46 | #include <linux/virtio_net.h> |
47 | #include <linux/virtio_blk.h> |
48 | #include <linux/virtio_console.h> |
49 | #include <linux/virtio_rng.h> |
50 | #include <linux/virtio_ring.h> |
51 | #include <asm/bootparam.h> |
52 | #include "../../include/linux/lguest_launcher.h" |
53 | /*L:110 |
54 | * We can ignore the 43 include files we need for this program, but I do want |
55 | * to draw attention to the use of kernel-style types. |
56 | * |
57 | * As Linus said, "C is a Spartan language, and so should your naming be." I |
58 | * like these abbreviations, so we define them here. Note that u64 is always |
59 | * unsigned long long, which works on all Linux systems: this means that we can |
60 | * use %llu in printf for any u64. |
61 | */ |
62 | typedef unsigned long long u64; |
63 | typedef uint32_t u32; |
64 | typedef uint16_t u16; |
65 | typedef uint8_t u8; |
66 | /*:*/ |
67 | |
68 | #define BRIDGE_PFX "bridge:" |
69 | #ifndef SIOCBRADDIF |
70 | #define SIOCBRADDIF 0x89a2 /* add interface to bridge */ |
71 | #endif |
72 | /* We can have up to 256 pages for devices. */ |
73 | #define DEVICE_PAGES 256 |
74 | /* This will occupy 3 pages: it must be a power of 2. */ |
75 | #define VIRTQUEUE_NUM 256 |
76 | |
77 | /*L:120 |
78 | * verbose is both a global flag and a macro. The C preprocessor allows |
79 | * this, and although I wouldn't recommend it, it works quite nicely here. |
80 | */ |
81 | static bool verbose; |
82 | #define verbose(args...) \ |
83 | do { if (verbose) printf(args); } while(0) |
84 | /*:*/ |
85 | |
86 | /* The pointer to the start of guest memory. */ |
87 | static void *guest_base; |
88 | /* The maximum guest physical address allowed, and maximum possible. */ |
89 | static unsigned long guest_limit, guest_max; |
90 | /* The /dev/lguest file descriptor. */ |
91 | static int lguest_fd; |
92 | |
93 | /* a per-cpu variable indicating whose vcpu is currently running */ |
94 | static unsigned int __thread cpu_id; |
95 | |
96 | /* This is our list of devices. */ |
97 | struct device_list { |
98 | /* Counter to assign interrupt numbers. */ |
99 | unsigned int next_irq; |
100 | |
101 | /* Counter to print out convenient device numbers. */ |
102 | unsigned int device_num; |
103 | |
104 | /* The descriptor page for the devices. */ |
105 | u8 *descpage; |
106 | |
107 | /* A single linked list of devices. */ |
108 | struct device *dev; |
109 | /* And a pointer to the last device for easy append. */ |
110 | struct device *lastdev; |
111 | }; |
112 | |
113 | /* The list of Guest devices, based on command line arguments. */ |
114 | static struct device_list devices; |
115 | |
116 | /* The device structure describes a single device. */ |
117 | struct device { |
118 | /* The linked-list pointer. */ |
119 | struct device *next; |
120 | |
121 | /* The device's descriptor, as mapped into the Guest. */ |
122 | struct lguest_device_desc *desc; |
123 | |
124 | /* We can't trust desc values once Guest has booted: we use these. */ |
125 | unsigned int feature_len; |
126 | unsigned int num_vq; |
127 | |
128 | /* The name of this device, for --verbose. */ |
129 | const char *name; |
130 | |
131 | /* Any queues attached to this device */ |
132 | struct virtqueue *vq; |
133 | |
134 | /* Is it operational */ |
135 | bool running; |
136 | |
137 | /* Device-specific data. */ |
138 | void *priv; |
139 | }; |
140 | |
141 | /* The virtqueue structure describes a queue attached to a device. */ |
142 | struct virtqueue { |
143 | struct virtqueue *next; |
144 | |
145 | /* Which device owns me. */ |
146 | struct device *dev; |
147 | |
148 | /* The configuration for this queue. */ |
149 | struct lguest_vqconfig config; |
150 | |
151 | /* The actual ring of buffers. */ |
152 | struct vring vring; |
153 | |
154 | /* Last available index we saw. */ |
155 | u16 last_avail_idx; |
156 | |
157 | /* How many are used since we sent last irq? */ |
158 | unsigned int pending_used; |
159 | |
160 | /* Eventfd where Guest notifications arrive. */ |
161 | int eventfd; |
162 | |
163 | /* Function for the thread which is servicing this virtqueue. */ |
164 | void (*service)(struct virtqueue *vq); |
165 | pid_t thread; |
166 | }; |
167 | |
168 | /* Remember the arguments to the program so we can "reboot" */ |
169 | static char **main_args; |
170 | |
171 | /* The original tty settings to restore on exit. */ |
172 | static struct termios orig_term; |
173 | |
174 | /* |
175 | * We have to be careful with barriers: our devices are all run in separate |
176 | * threads and so we need to make sure that changes visible to the Guest happen |
177 | * in precise order. |
178 | */ |
179 | #define wmb() __asm__ __volatile__("" : : : "memory") |
180 | #define mb() __asm__ __volatile__("" : : : "memory") |
181 | |
182 | /* Wrapper for the last available index. Makes it easier to change. */ |
183 | #define lg_last_avail(vq) ((vq)->last_avail_idx) |
184 | |
185 | /* |
186 | * The virtio configuration space is defined to be little-endian. x86 is |
187 | * little-endian too, but it's nice to be explicit so we have these helpers. |
188 | */ |
189 | #define cpu_to_le16(v16) (v16) |
190 | #define cpu_to_le32(v32) (v32) |
191 | #define cpu_to_le64(v64) (v64) |
192 | #define le16_to_cpu(v16) (v16) |
193 | #define le32_to_cpu(v32) (v32) |
194 | #define le64_to_cpu(v64) (v64) |
195 | |
196 | /* Is this iovec empty? */ |
197 | static bool iov_empty(const struct iovec iov[], unsigned int num_iov) |
198 | { |
199 | unsigned int i; |
200 | |
201 | for (i = 0; i < num_iov; i++) |
202 | if (iov[i].iov_len) |
203 | return false; |
204 | return true; |
205 | } |
206 | |
207 | /* Take len bytes from the front of this iovec. */ |
208 | static void iov_consume(struct iovec iov[], unsigned num_iov, |
209 | void *dest, unsigned len) |
210 | { |
211 | unsigned int i; |
212 | |
213 | for (i = 0; i < num_iov; i++) { |
214 | unsigned int used; |
215 | |
216 | used = iov[i].iov_len < len ? iov[i].iov_len : len; |
217 | if (dest) { |
218 | memcpy(dest, iov[i].iov_base, used); |
219 | dest += used; |
220 | } |
221 | iov[i].iov_base += used; |
222 | iov[i].iov_len -= used; |
223 | len -= used; |
224 | } |
225 | if (len != 0) |
226 | errx(1, "iovec too short!"); |
227 | } |
228 | |
229 | /* The device virtqueue descriptors are followed by feature bitmasks. */ |
230 | static u8 *get_feature_bits(struct device *dev) |
231 | { |
232 | return (u8 *)(dev->desc + 1) |
233 | + dev->num_vq * sizeof(struct lguest_vqconfig); |
234 | } |
235 | |
236 | /*L:100 |
237 | * The Launcher code itself takes us out into userspace, that scary place where |
238 | * pointers run wild and free! Unfortunately, like most userspace programs, |
239 | * it's quite boring (which is why everyone likes to hack on the kernel!). |
240 | * Perhaps if you make up an Lguest Drinking Game at this point, it will get |
241 | * you through this section. Or, maybe not. |
242 | * |
243 | * The Launcher sets up a big chunk of memory to be the Guest's "physical" |
244 | * memory and stores it in "guest_base". In other words, Guest physical == |
245 | * Launcher virtual with an offset. |
246 | * |
247 | * This can be tough to get your head around, but usually it just means that we |
248 | * use these trivial conversion functions when the Guest gives us its |
249 | * "physical" addresses: |
250 | */ |
251 | static void *from_guest_phys(unsigned long addr) |
252 | { |
253 | return guest_base + addr; |
254 | } |
255 | |
256 | static unsigned long to_guest_phys(const void *addr) |
257 | { |
258 | return (addr - guest_base); |
259 | } |
260 | |
261 | /*L:130 |
262 | * Loading the Kernel. |
263 | * |
264 | * We start with couple of simple helper routines. open_or_die() avoids |
265 | * error-checking code cluttering the callers: |
266 | */ |
267 | static int open_or_die(const char *name, int flags) |
268 | { |
269 | int fd = open(name, flags); |
270 | if (fd < 0) |
271 | err(1, "Failed to open %s", name); |
272 | return fd; |
273 | } |
274 | |
275 | /* map_zeroed_pages() takes a number of pages. */ |
276 | static void *map_zeroed_pages(unsigned int num) |
277 | { |
278 | int fd = open_or_die("/dev/zero", O_RDONLY); |
279 | void *addr; |
280 | |
281 | /* |
282 | * We use a private mapping (ie. if we write to the page, it will be |
283 | * copied). We allocate an extra two pages PROT_NONE to act as guard |
284 | * pages against read/write attempts that exceed allocated space. |
285 | */ |
286 | addr = mmap(NULL, getpagesize() * (num+2), |
287 | PROT_NONE, MAP_PRIVATE, fd, 0); |
288 | |
289 | if (addr == MAP_FAILED) |
290 | err(1, "Mmapping %u pages of /dev/zero", num); |
291 | |
292 | if (mprotect(addr + getpagesize(), getpagesize() * num, |
293 | PROT_READ|PROT_WRITE) == -1) |
294 | err(1, "mprotect rw %u pages failed", num); |
295 | |
296 | /* |
297 | * One neat mmap feature is that you can close the fd, and it |
298 | * stays mapped. |
299 | */ |
300 | close(fd); |
301 | |
302 | /* Return address after PROT_NONE page */ |
303 | return addr + getpagesize(); |
304 | } |
305 | |
306 | /* Get some more pages for a device. */ |
307 | static void *get_pages(unsigned int num) |
308 | { |
309 | void *addr = from_guest_phys(guest_limit); |
310 | |
311 | guest_limit += num * getpagesize(); |
312 | if (guest_limit > guest_max) |
313 | errx(1, "Not enough memory for devices"); |
314 | return addr; |
315 | } |
316 | |
317 | /* |
318 | * This routine is used to load the kernel or initrd. It tries mmap, but if |
319 | * that fails (Plan 9's kernel file isn't nicely aligned on page boundaries), |
320 | * it falls back to reading the memory in. |
321 | */ |
322 | static void map_at(int fd, void *addr, unsigned long offset, unsigned long len) |
323 | { |
324 | ssize_t r; |
325 | |
326 | /* |
327 | * We map writable even though for some segments are marked read-only. |
328 | * The kernel really wants to be writable: it patches its own |
329 | * instructions. |
330 | * |
331 | * MAP_PRIVATE means that the page won't be copied until a write is |
332 | * done to it. This allows us to share untouched memory between |
333 | * Guests. |
334 | */ |
335 | if (mmap(addr, len, PROT_READ|PROT_WRITE, |
336 | MAP_FIXED|MAP_PRIVATE, fd, offset) != MAP_FAILED) |
337 | return; |
338 | |
339 | /* pread does a seek and a read in one shot: saves a few lines. */ |
340 | r = pread(fd, addr, len, offset); |
341 | if (r != len) |
342 | err(1, "Reading offset %lu len %lu gave %zi", offset, len, r); |
343 | } |
344 | |
345 | /* |
346 | * This routine takes an open vmlinux image, which is in ELF, and maps it into |
347 | * the Guest memory. ELF = Embedded Linking Format, which is the format used |
348 | * by all modern binaries on Linux including the kernel. |
349 | * |
350 | * The ELF headers give *two* addresses: a physical address, and a virtual |
351 | * address. We use the physical address; the Guest will map itself to the |
352 | * virtual address. |
353 | * |
354 | * We return the starting address. |
355 | */ |
356 | static unsigned long map_elf(int elf_fd, const Elf32_Ehdr *ehdr) |
357 | { |
358 | Elf32_Phdr phdr[ehdr->e_phnum]; |
359 | unsigned int i; |
360 | |
361 | /* |
362 | * Sanity checks on the main ELF header: an x86 executable with a |
363 | * reasonable number of correctly-sized program headers. |
364 | */ |
365 | if (ehdr->e_type != ET_EXEC |
366 | || ehdr->e_machine != EM_386 |
367 | || ehdr->e_phentsize != sizeof(Elf32_Phdr) |
368 | || ehdr->e_phnum < 1 || ehdr->e_phnum > 65536U/sizeof(Elf32_Phdr)) |
369 | errx(1, "Malformed elf header"); |
370 | |
371 | /* |
372 | * An ELF executable contains an ELF header and a number of "program" |
373 | * headers which indicate which parts ("segments") of the program to |
374 | * load where. |
375 | */ |
376 | |
377 | /* We read in all the program headers at once: */ |
378 | if (lseek(elf_fd, ehdr->e_phoff, SEEK_SET) < 0) |
379 | err(1, "Seeking to program headers"); |
380 | if (read(elf_fd, phdr, sizeof(phdr)) != sizeof(phdr)) |
381 | err(1, "Reading program headers"); |
382 | |
383 | /* |
384 | * Try all the headers: there are usually only three. A read-only one, |
385 | * a read-write one, and a "note" section which we don't load. |
386 | */ |
387 | for (i = 0; i < ehdr->e_phnum; i++) { |
388 | /* If this isn't a loadable segment, we ignore it */ |
389 | if (phdr[i].p_type != PT_LOAD) |
390 | continue; |
391 | |
392 | verbose("Section %i: size %i addr %p\n", |
393 | i, phdr[i].p_memsz, (void *)phdr[i].p_paddr); |
394 | |
395 | /* We map this section of the file at its physical address. */ |
396 | map_at(elf_fd, from_guest_phys(phdr[i].p_paddr), |
397 | phdr[i].p_offset, phdr[i].p_filesz); |
398 | } |
399 | |
400 | /* The entry point is given in the ELF header. */ |
401 | return ehdr->e_entry; |
402 | } |
403 | |
404 | /*L:150 |
405 | * A bzImage, unlike an ELF file, is not meant to be loaded. You're supposed |
406 | * to jump into it and it will unpack itself. We used to have to perform some |
407 | * hairy magic because the unpacking code scared me. |
408 | * |
409 | * Fortunately, Jeremy Fitzhardinge convinced me it wasn't that hard and wrote |
410 | * a small patch to jump over the tricky bits in the Guest, so now we just read |
411 | * the funky header so we know where in the file to load, and away we go! |
412 | */ |
413 | static unsigned long load_bzimage(int fd) |
414 | { |
415 | struct boot_params boot; |
416 | int r; |
417 | /* Modern bzImages get loaded at 1M. */ |
418 | void *p = from_guest_phys(0x100000); |
419 | |
420 | /* |
421 | * Go back to the start of the file and read the header. It should be |
422 | * a Linux boot header (see Documentation/x86/boot.txt) |
423 | */ |
424 | lseek(fd, 0, SEEK_SET); |
425 | read(fd, &boot, sizeof(boot)); |
426 | |
427 | /* Inside the setup_hdr, we expect the magic "HdrS" */ |
428 | if (memcmp(&boot.hdr.header, "HdrS", 4) != 0) |
429 | errx(1, "This doesn't look like a bzImage to me"); |
430 | |
431 | /* Skip over the extra sectors of the header. */ |
432 | lseek(fd, (boot.hdr.setup_sects+1) * 512, SEEK_SET); |
433 | |
434 | /* Now read everything into memory. in nice big chunks. */ |
435 | while ((r = read(fd, p, 65536)) > 0) |
436 | p += r; |
437 | |
438 | /* Finally, code32_start tells us where to enter the kernel. */ |
439 | return boot.hdr.code32_start; |
440 | } |
441 | |
442 | /*L:140 |
443 | * Loading the kernel is easy when it's a "vmlinux", but most kernels |
444 | * come wrapped up in the self-decompressing "bzImage" format. With a little |
445 | * work, we can load those, too. |
446 | */ |
447 | static unsigned long load_kernel(int fd) |
448 | { |
449 | Elf32_Ehdr hdr; |
450 | |
451 | /* Read in the first few bytes. */ |
452 | if (read(fd, &hdr, sizeof(hdr)) != sizeof(hdr)) |
453 | err(1, "Reading kernel"); |
454 | |
455 | /* If it's an ELF file, it starts with "\177ELF" */ |
456 | if (memcmp(hdr.e_ident, ELFMAG, SELFMAG) == 0) |
457 | return map_elf(fd, &hdr); |
458 | |
459 | /* Otherwise we assume it's a bzImage, and try to load it. */ |
460 | return load_bzimage(fd); |
461 | } |
462 | |
463 | /* |
464 | * This is a trivial little helper to align pages. Andi Kleen hated it because |
465 | * it calls getpagesize() twice: "it's dumb code." |
466 | * |
467 | * Kernel guys get really het up about optimization, even when it's not |
468 | * necessary. I leave this code as a reaction against that. |
469 | */ |
470 | static inline unsigned long page_align(unsigned long addr) |
471 | { |
472 | /* Add upwards and truncate downwards. */ |
473 | return ((addr + getpagesize()-1) & ~(getpagesize()-1)); |
474 | } |
475 | |
476 | /*L:180 |
477 | * An "initial ram disk" is a disk image loaded into memory along with the |
478 | * kernel which the kernel can use to boot from without needing any drivers. |
479 | * Most distributions now use this as standard: the initrd contains the code to |
480 | * load the appropriate driver modules for the current machine. |
481 | * |
482 | * Importantly, James Morris works for RedHat, and Fedora uses initrds for its |
483 | * kernels. He sent me this (and tells me when I break it). |
484 | */ |
485 | static unsigned long load_initrd(const char *name, unsigned long mem) |
486 | { |
487 | int ifd; |
488 | struct stat st; |
489 | unsigned long len; |
490 | |
491 | ifd = open_or_die(name, O_RDONLY); |
492 | /* fstat() is needed to get the file size. */ |
493 | if (fstat(ifd, &st) < 0) |
494 | err(1, "fstat() on initrd '%s'", name); |
495 | |
496 | /* |
497 | * We map the initrd at the top of memory, but mmap wants it to be |
498 | * page-aligned, so we round the size up for that. |
499 | */ |
500 | len = page_align(st.st_size); |
501 | map_at(ifd, from_guest_phys(mem - len), 0, st.st_size); |
502 | /* |
503 | * Once a file is mapped, you can close the file descriptor. It's a |
504 | * little odd, but quite useful. |
505 | */ |
506 | close(ifd); |
507 | verbose("mapped initrd %s size=%lu @ %p\n", name, len, (void*)mem-len); |
508 | |
509 | /* We return the initrd size. */ |
510 | return len; |
511 | } |
512 | /*:*/ |
513 | |
514 | /* |
515 | * Simple routine to roll all the commandline arguments together with spaces |
516 | * between them. |
517 | */ |
518 | static void concat(char *dst, char *args[]) |
519 | { |
520 | unsigned int i, len = 0; |
521 | |
522 | for (i = 0; args[i]; i++) { |
523 | if (i) { |
524 | strcat(dst+len, " "); |
525 | len++; |
526 | } |
527 | strcpy(dst+len, args[i]); |
528 | len += strlen(args[i]); |
529 | } |
530 | /* In case it's empty. */ |
531 | dst[len] = '\0'; |
532 | } |
533 | |
534 | /*L:185 |
535 | * This is where we actually tell the kernel to initialize the Guest. We |
536 | * saw the arguments it expects when we looked at initialize() in lguest_user.c: |
537 | * the base of Guest "physical" memory, the top physical page to allow and the |
538 | * entry point for the Guest. |
539 | */ |
540 | static void tell_kernel(unsigned long start) |
541 | { |
542 | unsigned long args[] = { LHREQ_INITIALIZE, |
543 | (unsigned long)guest_base, |
544 | guest_limit / getpagesize(), start }; |
545 | verbose("Guest: %p - %p (%#lx)\n", |
546 | guest_base, guest_base + guest_limit, guest_limit); |
547 | lguest_fd = open_or_die("/dev/lguest", O_RDWR); |
548 | if (write(lguest_fd, args, sizeof(args)) < 0) |
549 | err(1, "Writing to /dev/lguest"); |
550 | } |
551 | /*:*/ |
552 | |
553 | /*L:200 |
554 | * Device Handling. |
555 | * |
556 | * When the Guest gives us a buffer, it sends an array of addresses and sizes. |
557 | * We need to make sure it's not trying to reach into the Launcher itself, so |
558 | * we have a convenient routine which checks it and exits with an error message |
559 | * if something funny is going on: |
560 | */ |
561 | static void *_check_pointer(unsigned long addr, unsigned int size, |
562 | unsigned int line) |
563 | { |
564 | /* |
565 | * Check if the requested address and size exceeds the allocated memory, |
566 | * or addr + size wraps around. |
567 | */ |
568 | if ((addr + size) > guest_limit || (addr + size) < addr) |
569 | errx(1, "%s:%i: Invalid address %#lx", __FILE__, line, addr); |
570 | /* |
571 | * We return a pointer for the caller's convenience, now we know it's |
572 | * safe to use. |
573 | */ |
574 | return from_guest_phys(addr); |
575 | } |
576 | /* A macro which transparently hands the line number to the real function. */ |
577 | #define check_pointer(addr,size) _check_pointer(addr, size, __LINE__) |
578 | |
579 | /* |
580 | * Each buffer in the virtqueues is actually a chain of descriptors. This |
581 | * function returns the next descriptor in the chain, or vq->vring.num if we're |
582 | * at the end. |
583 | */ |
584 | static unsigned next_desc(struct vring_desc *desc, |
585 | unsigned int i, unsigned int max) |
586 | { |
587 | unsigned int next; |
588 | |
589 | /* If this descriptor says it doesn't chain, we're done. */ |
590 | if (!(desc[i].flags & VRING_DESC_F_NEXT)) |
591 | return max; |
592 | |
593 | /* Check they're not leading us off end of descriptors. */ |
594 | next = desc[i].next; |
595 | /* Make sure compiler knows to grab that: we don't want it changing! */ |
596 | wmb(); |
597 | |
598 | if (next >= max) |
599 | errx(1, "Desc next is %u", next); |
600 | |
601 | return next; |
602 | } |
603 | |
604 | /* |
605 | * This actually sends the interrupt for this virtqueue, if we've used a |
606 | * buffer. |
607 | */ |
608 | static void trigger_irq(struct virtqueue *vq) |
609 | { |
610 | unsigned long buf[] = { LHREQ_IRQ, vq->config.irq }; |
611 | |
612 | /* Don't inform them if nothing used. */ |
613 | if (!vq->pending_used) |
614 | return; |
615 | vq->pending_used = 0; |
616 | |
617 | /* If they don't want an interrupt, don't send one... */ |
618 | if (vq->vring.avail->flags & VRING_AVAIL_F_NO_INTERRUPT) { |
619 | return; |
620 | } |
621 | |
622 | /* Send the Guest an interrupt tell them we used something up. */ |
623 | if (write(lguest_fd, buf, sizeof(buf)) != 0) |
624 | err(1, "Triggering irq %i", vq->config.irq); |
625 | } |
626 | |
627 | /* |
628 | * This looks in the virtqueue for the first available buffer, and converts |
629 | * it to an iovec for convenient access. Since descriptors consist of some |
630 | * number of output then some number of input descriptors, it's actually two |
631 | * iovecs, but we pack them into one and note how many of each there were. |
632 | * |
633 | * This function waits if necessary, and returns the descriptor number found. |
634 | */ |
635 | static unsigned wait_for_vq_desc(struct virtqueue *vq, |
636 | struct iovec iov[], |
637 | unsigned int *out_num, unsigned int *in_num) |
638 | { |
639 | unsigned int i, head, max; |
640 | struct vring_desc *desc; |
641 | u16 last_avail = lg_last_avail(vq); |
642 | |
643 | /* There's nothing available? */ |
644 | while (last_avail == vq->vring.avail->idx) { |
645 | u64 event; |
646 | |
647 | /* |
648 | * Since we're about to sleep, now is a good time to tell the |
649 | * Guest about what we've used up to now. |
650 | */ |
651 | trigger_irq(vq); |
652 | |
653 | /* OK, now we need to know about added descriptors. */ |
654 | vq->vring.used->flags &= ~VRING_USED_F_NO_NOTIFY; |
655 | |
656 | /* |
657 | * They could have slipped one in as we were doing that: make |
658 | * sure it's written, then check again. |
659 | */ |
660 | mb(); |
661 | if (last_avail != vq->vring.avail->idx) { |
662 | vq->vring.used->flags |= VRING_USED_F_NO_NOTIFY; |
663 | break; |
664 | } |
665 | |
666 | /* Nothing new? Wait for eventfd to tell us they refilled. */ |
667 | if (read(vq->eventfd, &event, sizeof(event)) != sizeof(event)) |
668 | errx(1, "Event read failed?"); |
669 | |
670 | /* We don't need to be notified again. */ |
671 | vq->vring.used->flags |= VRING_USED_F_NO_NOTIFY; |
672 | } |
673 | |
674 | /* Check it isn't doing very strange things with descriptor numbers. */ |
675 | if ((u16)(vq->vring.avail->idx - last_avail) > vq->vring.num) |
676 | errx(1, "Guest moved used index from %u to %u", |
677 | last_avail, vq->vring.avail->idx); |
678 | |
679 | /* |
680 | * Grab the next descriptor number they're advertising, and increment |
681 | * the index we've seen. |
682 | */ |
683 | head = vq->vring.avail->ring[last_avail % vq->vring.num]; |
684 | lg_last_avail(vq)++; |
685 | |
686 | /* If their number is silly, that's a fatal mistake. */ |
687 | if (head >= vq->vring.num) |
688 | errx(1, "Guest says index %u is available", head); |
689 | |
690 | /* When we start there are none of either input nor output. */ |
691 | *out_num = *in_num = 0; |
692 | |
693 | max = vq->vring.num; |
694 | desc = vq->vring.desc; |
695 | i = head; |
696 | |
697 | /* |
698 | * If this is an indirect entry, then this buffer contains a descriptor |
699 | * table which we handle as if it's any normal descriptor chain. |
700 | */ |
701 | if (desc[i].flags & VRING_DESC_F_INDIRECT) { |
702 | if (desc[i].len % sizeof(struct vring_desc)) |
703 | errx(1, "Invalid size for indirect buffer table"); |
704 | |
705 | max = desc[i].len / sizeof(struct vring_desc); |
706 | desc = check_pointer(desc[i].addr, desc[i].len); |
707 | i = 0; |
708 | } |
709 | |
710 | do { |
711 | /* Grab the first descriptor, and check it's OK. */ |
712 | iov[*out_num + *in_num].iov_len = desc[i].len; |
713 | iov[*out_num + *in_num].iov_base |
714 | = check_pointer(desc[i].addr, desc[i].len); |
715 | /* If this is an input descriptor, increment that count. */ |
716 | if (desc[i].flags & VRING_DESC_F_WRITE) |
717 | (*in_num)++; |
718 | else { |
719 | /* |
720 | * If it's an output descriptor, they're all supposed |
721 | * to come before any input descriptors. |
722 | */ |
723 | if (*in_num) |
724 | errx(1, "Descriptor has out after in"); |
725 | (*out_num)++; |
726 | } |
727 | |
728 | /* If we've got too many, that implies a descriptor loop. */ |
729 | if (*out_num + *in_num > max) |
730 | errx(1, "Looped descriptor"); |
731 | } while ((i = next_desc(desc, i, max)) != max); |
732 | |
733 | return head; |
734 | } |
735 | |
736 | /* |
737 | * After we've used one of their buffers, we tell the Guest about it. Sometime |
738 | * later we'll want to send them an interrupt using trigger_irq(); note that |
739 | * wait_for_vq_desc() does that for us if it has to wait. |
740 | */ |
741 | static void add_used(struct virtqueue *vq, unsigned int head, int len) |
742 | { |
743 | struct vring_used_elem *used; |
744 | |
745 | /* |
746 | * The virtqueue contains a ring of used buffers. Get a pointer to the |
747 | * next entry in that used ring. |
748 | */ |
749 | used = &vq->vring.used->ring[vq->vring.used->idx % vq->vring.num]; |
750 | used->id = head; |
751 | used->len = len; |
752 | /* Make sure buffer is written before we update index. */ |
753 | wmb(); |
754 | vq->vring.used->idx++; |
755 | vq->pending_used++; |
756 | } |
757 | |
758 | /* And here's the combo meal deal. Supersize me! */ |
759 | static void add_used_and_trigger(struct virtqueue *vq, unsigned head, int len) |
760 | { |
761 | add_used(vq, head, len); |
762 | trigger_irq(vq); |
763 | } |
764 | |
765 | /* |
766 | * The Console |
767 | * |
768 | * We associate some data with the console for our exit hack. |
769 | */ |
770 | struct console_abort { |
771 | /* How many times have they hit ^C? */ |
772 | int count; |
773 | /* When did they start? */ |
774 | struct timeval start; |
775 | }; |
776 | |
777 | /* This is the routine which handles console input (ie. stdin). */ |
778 | static void console_input(struct virtqueue *vq) |
779 | { |
780 | int len; |
781 | unsigned int head, in_num, out_num; |
782 | struct console_abort *abort = vq->dev->priv; |
783 | struct iovec iov[vq->vring.num]; |
784 | |
785 | /* Make sure there's a descriptor available. */ |
786 | head = wait_for_vq_desc(vq, iov, &out_num, &in_num); |
787 | if (out_num) |
788 | errx(1, "Output buffers in console in queue?"); |
789 | |
790 | /* Read into it. This is where we usually wait. */ |
791 | len = readv(STDIN_FILENO, iov, in_num); |
792 | if (len <= 0) { |
793 | /* Ran out of input? */ |
794 | warnx("Failed to get console input, ignoring console."); |
795 | /* |
796 | * For simplicity, dying threads kill the whole Launcher. So |
797 | * just nap here. |
798 | */ |
799 | for (;;) |
800 | pause(); |
801 | } |
802 | |
803 | /* Tell the Guest we used a buffer. */ |
804 | add_used_and_trigger(vq, head, len); |
805 | |
806 | /* |
807 | * Three ^C within one second? Exit. |
808 | * |
809 | * This is such a hack, but works surprisingly well. Each ^C has to |
810 | * be in a buffer by itself, so they can't be too fast. But we check |
811 | * that we get three within about a second, so they can't be too |
812 | * slow. |
813 | */ |
814 | if (len != 1 || ((char *)iov[0].iov_base)[0] != 3) { |
815 | abort->count = 0; |
816 | return; |
817 | } |
818 | |
819 | abort->count++; |
820 | if (abort->count == 1) |
821 | gettimeofday(&abort->start, NULL); |
822 | else if (abort->count == 3) { |
823 | struct timeval now; |
824 | gettimeofday(&now, NULL); |
825 | /* Kill all Launcher processes with SIGINT, like normal ^C */ |
826 | if (now.tv_sec <= abort->start.tv_sec+1) |
827 | kill(0, SIGINT); |
828 | abort->count = 0; |
829 | } |
830 | } |
831 | |
832 | /* This is the routine which handles console output (ie. stdout). */ |
833 | static void console_output(struct virtqueue *vq) |
834 | { |
835 | unsigned int head, out, in; |
836 | struct iovec iov[vq->vring.num]; |
837 | |
838 | /* We usually wait in here, for the Guest to give us something. */ |
839 | head = wait_for_vq_desc(vq, iov, &out, &in); |
840 | if (in) |
841 | errx(1, "Input buffers in console output queue?"); |
842 | |
843 | /* writev can return a partial write, so we loop here. */ |
844 | while (!iov_empty(iov, out)) { |
845 | int len = writev(STDOUT_FILENO, iov, out); |
846 | if (len <= 0) { |
847 | warn("Write to stdout gave %i (%d)", len, errno); |
848 | break; |
849 | } |
850 | iov_consume(iov, out, NULL, len); |
851 | } |
852 | |
853 | /* |
854 | * We're finished with that buffer: if we're going to sleep, |
855 | * wait_for_vq_desc() will prod the Guest with an interrupt. |
856 | */ |
857 | add_used(vq, head, 0); |
858 | } |
859 | |
860 | /* |
861 | * The Network |
862 | * |
863 | * Handling output for network is also simple: we get all the output buffers |
864 | * and write them to /dev/net/tun. |
865 | */ |
866 | struct net_info { |
867 | int tunfd; |
868 | }; |
869 | |
870 | static void net_output(struct virtqueue *vq) |
871 | { |
872 | struct net_info *net_info = vq->dev->priv; |
873 | unsigned int head, out, in; |
874 | struct iovec iov[vq->vring.num]; |
875 | |
876 | /* We usually wait in here for the Guest to give us a packet. */ |
877 | head = wait_for_vq_desc(vq, iov, &out, &in); |
878 | if (in) |
879 | errx(1, "Input buffers in net output queue?"); |
880 | /* |
881 | * Send the whole thing through to /dev/net/tun. It expects the exact |
882 | * same format: what a coincidence! |
883 | */ |
884 | if (writev(net_info->tunfd, iov, out) < 0) |
885 | warnx("Write to tun failed (%d)?", errno); |
886 | |
887 | /* |
888 | * Done with that one; wait_for_vq_desc() will send the interrupt if |
889 | * all packets are processed. |
890 | */ |
891 | add_used(vq, head, 0); |
892 | } |
893 | |
894 | /* |
895 | * Handling network input is a bit trickier, because I've tried to optimize it. |
896 | * |
897 | * First we have a helper routine which tells is if from this file descriptor |
898 | * (ie. the /dev/net/tun device) will block: |
899 | */ |
900 | static bool will_block(int fd) |
901 | { |
902 | fd_set fdset; |
903 | struct timeval zero = { 0, 0 }; |
904 | FD_ZERO(&fdset); |
905 | FD_SET(fd, &fdset); |
906 | return select(fd+1, &fdset, NULL, NULL, &zero) != 1; |
907 | } |
908 | |
909 | /* |
910 | * This handles packets coming in from the tun device to our Guest. Like all |
911 | * service routines, it gets called again as soon as it returns, so you don't |
912 | * see a while(1) loop here. |
913 | */ |
914 | static void net_input(struct virtqueue *vq) |
915 | { |
916 | int len; |
917 | unsigned int head, out, in; |
918 | struct iovec iov[vq->vring.num]; |
919 | struct net_info *net_info = vq->dev->priv; |
920 | |
921 | /* |
922 | * Get a descriptor to write an incoming packet into. This will also |
923 | * send an interrupt if they're out of descriptors. |
924 | */ |
925 | head = wait_for_vq_desc(vq, iov, &out, &in); |
926 | if (out) |
927 | errx(1, "Output buffers in net input queue?"); |
928 | |
929 | /* |
930 | * If it looks like we'll block reading from the tun device, send them |
931 | * an interrupt. |
932 | */ |
933 | if (vq->pending_used && will_block(net_info->tunfd)) |
934 | trigger_irq(vq); |
935 | |
936 | /* |
937 | * Read in the packet. This is where we normally wait (when there's no |
938 | * incoming network traffic). |
939 | */ |
940 | len = readv(net_info->tunfd, iov, in); |
941 | if (len <= 0) |
942 | warn("Failed to read from tun (%d).", errno); |
943 | |
944 | /* |
945 | * Mark that packet buffer as used, but don't interrupt here. We want |
946 | * to wait until we've done as much work as we can. |
947 | */ |
948 | add_used(vq, head, len); |
949 | } |
950 | /*:*/ |
951 | |
952 | /* This is the helper to create threads: run the service routine in a loop. */ |
953 | static int do_thread(void *_vq) |
954 | { |
955 | struct virtqueue *vq = _vq; |
956 | |
957 | for (;;) |
958 | vq->service(vq); |
959 | return 0; |
960 | } |
961 | |
962 | /* |
963 | * When a child dies, we kill our entire process group with SIGTERM. This |
964 | * also has the side effect that the shell restores the console for us! |
965 | */ |
966 | static void kill_launcher(int signal) |
967 | { |
968 | kill(0, SIGTERM); |
969 | } |
970 | |
971 | static void reset_device(struct device *dev) |
972 | { |
973 | struct virtqueue *vq; |
974 | |
975 | verbose("Resetting device %s\n", dev->name); |
976 | |
977 | /* Clear any features they've acked. */ |
978 | memset(get_feature_bits(dev) + dev->feature_len, 0, dev->feature_len); |
979 | |
980 | /* We're going to be explicitly killing threads, so ignore them. */ |
981 | signal(SIGCHLD, SIG_IGN); |
982 | |
983 | /* Zero out the virtqueues, get rid of their threads */ |
984 | for (vq = dev->vq; vq; vq = vq->next) { |
985 | if (vq->thread != (pid_t)-1) { |
986 | kill(vq->thread, SIGTERM); |
987 | waitpid(vq->thread, NULL, 0); |
988 | vq->thread = (pid_t)-1; |
989 | } |
990 | memset(vq->vring.desc, 0, |
991 | vring_size(vq->config.num, LGUEST_VRING_ALIGN)); |
992 | lg_last_avail(vq) = 0; |
993 | } |
994 | dev->running = false; |
995 | |
996 | /* Now we care if threads die. */ |
997 | signal(SIGCHLD, (void *)kill_launcher); |
998 | } |
999 | |
1000 | /*L:216 |
1001 | * This actually creates the thread which services the virtqueue for a device. |
1002 | */ |
1003 | static void create_thread(struct virtqueue *vq) |
1004 | { |
1005 | /* |
1006 | * Create stack for thread. Since the stack grows upwards, we point |
1007 | * the stack pointer to the end of this region. |
1008 | */ |
1009 | char *stack = malloc(32768); |
1010 | unsigned long args[] = { LHREQ_EVENTFD, |
1011 | vq->config.pfn*getpagesize(), 0 }; |
1012 | |
1013 | /* Create a zero-initialized eventfd. */ |
1014 | vq->eventfd = eventfd(0, 0); |
1015 | if (vq->eventfd < 0) |
1016 | err(1, "Creating eventfd"); |
1017 | args[2] = vq->eventfd; |
1018 | |
1019 | /* |
1020 | * Attach an eventfd to this virtqueue: it will go off when the Guest |
1021 | * does an LHCALL_NOTIFY for this vq. |
1022 | */ |
1023 | if (write(lguest_fd, &args, sizeof(args)) != 0) |
1024 | err(1, "Attaching eventfd"); |
1025 | |
1026 | /* |
1027 | * CLONE_VM: because it has to access the Guest memory, and SIGCHLD so |
1028 | * we get a signal if it dies. |
1029 | */ |
1030 | vq->thread = clone(do_thread, stack + 32768, CLONE_VM | SIGCHLD, vq); |
1031 | if (vq->thread == (pid_t)-1) |
1032 | err(1, "Creating clone"); |
1033 | |
1034 | /* We close our local copy now the child has it. */ |
1035 | close(vq->eventfd); |
1036 | } |
1037 | |
1038 | static void start_device(struct device *dev) |
1039 | { |
1040 | unsigned int i; |
1041 | struct virtqueue *vq; |
1042 | |
1043 | verbose("Device %s OK: offered", dev->name); |
1044 | for (i = 0; i < dev->feature_len; i++) |
1045 | verbose(" %02x", get_feature_bits(dev)[i]); |
1046 | verbose(", accepted"); |
1047 | for (i = 0; i < dev->feature_len; i++) |
1048 | verbose(" %02x", get_feature_bits(dev) |
1049 | [dev->feature_len+i]); |
1050 | |
1051 | for (vq = dev->vq; vq; vq = vq->next) { |
1052 | if (vq->service) |
1053 | create_thread(vq); |
1054 | } |
1055 | dev->running = true; |
1056 | } |
1057 | |
1058 | static void cleanup_devices(void) |
1059 | { |
1060 | struct device *dev; |
1061 | |
1062 | for (dev = devices.dev; dev; dev = dev->next) |
1063 | reset_device(dev); |
1064 | |
1065 | /* If we saved off the original terminal settings, restore them now. */ |
1066 | if (orig_term.c_lflag & (ISIG|ICANON|ECHO)) |
1067 | tcsetattr(STDIN_FILENO, TCSANOW, &orig_term); |
1068 | } |
1069 | |
1070 | /* When the Guest tells us they updated the status field, we handle it. */ |
1071 | static void update_device_status(struct device *dev) |
1072 | { |
1073 | /* A zero status is a reset, otherwise it's a set of flags. */ |
1074 | if (dev->desc->status == 0) |
1075 | reset_device(dev); |
1076 | else if (dev->desc->status & VIRTIO_CONFIG_S_FAILED) { |
1077 | warnx("Device %s configuration FAILED", dev->name); |
1078 | if (dev->running) |
1079 | reset_device(dev); |
1080 | } else { |
1081 | if (dev->running) |
1082 | err(1, "Device %s features finalized twice", dev->name); |
1083 | start_device(dev); |
1084 | } |
1085 | } |
1086 | |
1087 | /*L:215 |
1088 | * This is the generic routine we call when the Guest uses LHCALL_NOTIFY. In |
1089 | * particular, it's used to notify us of device status changes during boot. |
1090 | */ |
1091 | static void handle_output(unsigned long addr) |
1092 | { |
1093 | struct device *i; |
1094 | |
1095 | /* Check each device. */ |
1096 | for (i = devices.dev; i; i = i->next) { |
1097 | struct virtqueue *vq; |
1098 | |
1099 | /* |
1100 | * Notifications to device descriptors mean they updated the |
1101 | * device status. |
1102 | */ |
1103 | if (from_guest_phys(addr) == i->desc) { |
1104 | update_device_status(i); |
1105 | return; |
1106 | } |
1107 | |
1108 | /* Devices should not be used before features are finalized. */ |
1109 | for (vq = i->vq; vq; vq = vq->next) { |
1110 | if (addr != vq->config.pfn*getpagesize()) |
1111 | continue; |
1112 | errx(1, "Notification on %s before setup!", i->name); |
1113 | } |
1114 | } |
1115 | |
1116 | /* |
1117 | * Early console write is done using notify on a nul-terminated string |
1118 | * in Guest memory. It's also great for hacking debugging messages |
1119 | * into a Guest. |
1120 | */ |
1121 | if (addr >= guest_limit) |
1122 | errx(1, "Bad NOTIFY %#lx", addr); |
1123 | |
1124 | write(STDOUT_FILENO, from_guest_phys(addr), |
1125 | strnlen(from_guest_phys(addr), guest_limit - addr)); |
1126 | } |
1127 | |
1128 | /*L:190 |
1129 | * Device Setup |
1130 | * |
1131 | * All devices need a descriptor so the Guest knows it exists, and a "struct |
1132 | * device" so the Launcher can keep track of it. We have common helper |
1133 | * routines to allocate and manage them. |
1134 | */ |
1135 | |
1136 | /* |
1137 | * The layout of the device page is a "struct lguest_device_desc" followed by a |
1138 | * number of virtqueue descriptors, then two sets of feature bits, then an |
1139 | * array of configuration bytes. This routine returns the configuration |
1140 | * pointer. |
1141 | */ |
1142 | static u8 *device_config(const struct device *dev) |
1143 | { |
1144 | return (void *)(dev->desc + 1) |
1145 | + dev->num_vq * sizeof(struct lguest_vqconfig) |
1146 | + dev->feature_len * 2; |
1147 | } |
1148 | |
1149 | /* |
1150 | * This routine allocates a new "struct lguest_device_desc" from descriptor |
1151 | * table page just above the Guest's normal memory. It returns a pointer to |
1152 | * that descriptor. |
1153 | */ |
1154 | static struct lguest_device_desc *new_dev_desc(u16 type) |
1155 | { |
1156 | struct lguest_device_desc d = { .type = type }; |
1157 | void *p; |
1158 | |
1159 | /* Figure out where the next device config is, based on the last one. */ |
1160 | if (devices.lastdev) |
1161 | p = device_config(devices.lastdev) |
1162 | + devices.lastdev->desc->config_len; |
1163 | else |
1164 | p = devices.descpage; |
1165 | |
1166 | /* We only have one page for all the descriptors. */ |
1167 | if (p + sizeof(d) > (void *)devices.descpage + getpagesize()) |
1168 | errx(1, "Too many devices"); |
1169 | |
1170 | /* p might not be aligned, so we memcpy in. */ |
1171 | return memcpy(p, &d, sizeof(d)); |
1172 | } |
1173 | |
1174 | /* |
1175 | * Each device descriptor is followed by the description of its virtqueues. We |
1176 | * specify how many descriptors the virtqueue is to have. |
1177 | */ |
1178 | static void add_virtqueue(struct device *dev, unsigned int num_descs, |
1179 | void (*service)(struct virtqueue *)) |
1180 | { |
1181 | unsigned int pages; |
1182 | struct virtqueue **i, *vq = malloc(sizeof(*vq)); |
1183 | void *p; |
1184 | |
1185 | /* First we need some memory for this virtqueue. */ |
1186 | pages = (vring_size(num_descs, LGUEST_VRING_ALIGN) + getpagesize() - 1) |
1187 | / getpagesize(); |
1188 | p = get_pages(pages); |
1189 | |
1190 | /* Initialize the virtqueue */ |
1191 | vq->next = NULL; |
1192 | vq->last_avail_idx = 0; |
1193 | vq->dev = dev; |
1194 | |
1195 | /* |
1196 | * This is the routine the service thread will run, and its Process ID |
1197 | * once it's running. |
1198 | */ |
1199 | vq->service = service; |
1200 | vq->thread = (pid_t)-1; |
1201 | |
1202 | /* Initialize the configuration. */ |
1203 | vq->config.num = num_descs; |
1204 | vq->config.irq = devices.next_irq++; |
1205 | vq->config.pfn = to_guest_phys(p) / getpagesize(); |
1206 | |
1207 | /* Initialize the vring. */ |
1208 | vring_init(&vq->vring, num_descs, p, LGUEST_VRING_ALIGN); |
1209 | |
1210 | /* |
1211 | * Append virtqueue to this device's descriptor. We use |
1212 | * device_config() to get the end of the device's current virtqueues; |
1213 | * we check that we haven't added any config or feature information |
1214 | * yet, otherwise we'd be overwriting them. |
1215 | */ |
1216 | assert(dev->desc->config_len == 0 && dev->desc->feature_len == 0); |
1217 | memcpy(device_config(dev), &vq->config, sizeof(vq->config)); |
1218 | dev->num_vq++; |
1219 | dev->desc->num_vq++; |
1220 | |
1221 | verbose("Virtqueue page %#lx\n", to_guest_phys(p)); |
1222 | |
1223 | /* |
1224 | * Add to tail of list, so dev->vq is first vq, dev->vq->next is |
1225 | * second. |
1226 | */ |
1227 | for (i = &dev->vq; *i; i = &(*i)->next); |
1228 | *i = vq; |
1229 | } |
1230 | |
1231 | /* |
1232 | * The first half of the feature bitmask is for us to advertise features. The |
1233 | * second half is for the Guest to accept features. |
1234 | */ |
1235 | static void add_feature(struct device *dev, unsigned bit) |
1236 | { |
1237 | u8 *features = get_feature_bits(dev); |
1238 | |
1239 | /* We can't extend the feature bits once we've added config bytes */ |
1240 | if (dev->desc->feature_len <= bit / CHAR_BIT) { |
1241 | assert(dev->desc->config_len == 0); |
1242 | dev->feature_len = dev->desc->feature_len = (bit/CHAR_BIT) + 1; |
1243 | } |
1244 | |
1245 | features[bit / CHAR_BIT] |= (1 << (bit % CHAR_BIT)); |
1246 | } |
1247 | |
1248 | /* |
1249 | * This routine sets the configuration fields for an existing device's |
1250 | * descriptor. It only works for the last device, but that's OK because that's |
1251 | * how we use it. |
1252 | */ |
1253 | static void set_config(struct device *dev, unsigned len, const void *conf) |
1254 | { |
1255 | /* Check we haven't overflowed our single page. */ |
1256 | if (device_config(dev) + len > devices.descpage + getpagesize()) |
1257 | errx(1, "Too many devices"); |
1258 | |
1259 | /* Copy in the config information, and store the length. */ |
1260 | memcpy(device_config(dev), conf, len); |
1261 | dev->desc->config_len = len; |
1262 | |
1263 | /* Size must fit in config_len field (8 bits)! */ |
1264 | assert(dev->desc->config_len == len); |
1265 | } |
1266 | |
1267 | /* |
1268 | * This routine does all the creation and setup of a new device, including |
1269 | * calling new_dev_desc() to allocate the descriptor and device memory. We |
1270 | * don't actually start the service threads until later. |
1271 | * |
1272 | * See what I mean about userspace being boring? |
1273 | */ |
1274 | static struct device *new_device(const char *name, u16 type) |
1275 | { |
1276 | struct device *dev = malloc(sizeof(*dev)); |
1277 | |
1278 | /* Now we populate the fields one at a time. */ |
1279 | dev->desc = new_dev_desc(type); |
1280 | dev->name = name; |
1281 | dev->vq = NULL; |
1282 | dev->feature_len = 0; |
1283 | dev->num_vq = 0; |
1284 | dev->running = false; |
1285 | dev->next = NULL; |
1286 | |
1287 | /* |
1288 | * Append to device list. Prepending to a single-linked list is |
1289 | * easier, but the user expects the devices to be arranged on the bus |
1290 | * in command-line order. The first network device on the command line |
1291 | * is eth0, the first block device /dev/vda, etc. |
1292 | */ |
1293 | if (devices.lastdev) |
1294 | devices.lastdev->next = dev; |
1295 | else |
1296 | devices.dev = dev; |
1297 | devices.lastdev = dev; |
1298 | |
1299 | return dev; |
1300 | } |
1301 | |
1302 | /* |
1303 | * Our first setup routine is the console. It's a fairly simple device, but |
1304 | * UNIX tty handling makes it uglier than it could be. |
1305 | */ |
1306 | static void setup_console(void) |
1307 | { |
1308 | struct device *dev; |
1309 | |
1310 | /* If we can save the initial standard input settings... */ |
1311 | if (tcgetattr(STDIN_FILENO, &orig_term) == 0) { |
1312 | struct termios term = orig_term; |
1313 | /* |
1314 | * Then we turn off echo, line buffering and ^C etc: We want a |
1315 | * raw input stream to the Guest. |
1316 | */ |
1317 | term.c_lflag &= ~(ISIG|ICANON|ECHO); |
1318 | tcsetattr(STDIN_FILENO, TCSANOW, &term); |
1319 | } |
1320 | |
1321 | dev = new_device("console", VIRTIO_ID_CONSOLE); |
1322 | |
1323 | /* We store the console state in dev->priv, and initialize it. */ |
1324 | dev->priv = malloc(sizeof(struct console_abort)); |
1325 | ((struct console_abort *)dev->priv)->count = 0; |
1326 | |
1327 | /* |
1328 | * The console needs two virtqueues: the input then the output. When |
1329 | * they put something the input queue, we make sure we're listening to |
1330 | * stdin. When they put something in the output queue, we write it to |
1331 | * stdout. |
1332 | */ |
1333 | add_virtqueue(dev, VIRTQUEUE_NUM, console_input); |
1334 | add_virtqueue(dev, VIRTQUEUE_NUM, console_output); |
1335 | |
1336 | verbose("device %u: console\n", ++devices.device_num); |
1337 | } |
1338 | /*:*/ |
1339 | |
1340 | /*M:010 |
1341 | * Inter-guest networking is an interesting area. Simplest is to have a |
1342 | * --sharenet=<name> option which opens or creates a named pipe. This can be |
1343 | * used to send packets to another guest in a 1:1 manner. |
1344 | * |
1345 | * More sophisticated is to use one of the tools developed for project like UML |
1346 | * to do networking. |
1347 | * |
1348 | * Faster is to do virtio bonding in kernel. Doing this 1:1 would be |
1349 | * completely generic ("here's my vring, attach to your vring") and would work |
1350 | * for any traffic. Of course, namespace and permissions issues need to be |
1351 | * dealt with. A more sophisticated "multi-channel" virtio_net.c could hide |
1352 | * multiple inter-guest channels behind one interface, although it would |
1353 | * require some manner of hotplugging new virtio channels. |
1354 | * |
1355 | * Finally, we could use a virtio network switch in the kernel, ie. vhost. |
1356 | :*/ |
1357 | |
1358 | static u32 str2ip(const char *ipaddr) |
1359 | { |
1360 | unsigned int b[4]; |
1361 | |
1362 | if (sscanf(ipaddr, "%u.%u.%u.%u", &b[0], &b[1], &b[2], &b[3]) != 4) |
1363 | errx(1, "Failed to parse IP address '%s'", ipaddr); |
1364 | return (b[0] << 24) | (b[1] << 16) | (b[2] << 8) | b[3]; |
1365 | } |
1366 | |
1367 | static void str2mac(const char *macaddr, unsigned char mac[6]) |
1368 | { |
1369 | unsigned int m[6]; |
1370 | if (sscanf(macaddr, "%02x:%02x:%02x:%02x:%02x:%02x", |
1371 | &m[0], &m[1], &m[2], &m[3], &m[4], &m[5]) != 6) |
1372 | errx(1, "Failed to parse mac address '%s'", macaddr); |
1373 | mac[0] = m[0]; |
1374 | mac[1] = m[1]; |
1375 | mac[2] = m[2]; |
1376 | mac[3] = m[3]; |
1377 | mac[4] = m[4]; |
1378 | mac[5] = m[5]; |
1379 | } |
1380 | |
1381 | /* |
1382 | * This code is "adapted" from libbridge: it attaches the Host end of the |
1383 | * network device to the bridge device specified by the command line. |
1384 | * |
1385 | * This is yet another James Morris contribution (I'm an IP-level guy, so I |
1386 | * dislike bridging), and I just try not to break it. |
1387 | */ |
1388 | static void add_to_bridge(int fd, const char *if_name, const char *br_name) |
1389 | { |
1390 | int ifidx; |
1391 | struct ifreq ifr; |
1392 | |
1393 | if (!*br_name) |
1394 | errx(1, "must specify bridge name"); |
1395 | |
1396 | ifidx = if_nametoindex(if_name); |
1397 | if (!ifidx) |
1398 | errx(1, "interface %s does not exist!", if_name); |
1399 | |
1400 | strncpy(ifr.ifr_name, br_name, IFNAMSIZ); |
1401 | ifr.ifr_name[IFNAMSIZ-1] = '\0'; |
1402 | ifr.ifr_ifindex = ifidx; |
1403 | if (ioctl(fd, SIOCBRADDIF, &ifr) < 0) |
1404 | err(1, "can't add %s to bridge %s", if_name, br_name); |
1405 | } |
1406 | |
1407 | /* |
1408 | * This sets up the Host end of the network device with an IP address, brings |
1409 | * it up so packets will flow, the copies the MAC address into the hwaddr |
1410 | * pointer. |
1411 | */ |
1412 | static void configure_device(int fd, const char *tapif, u32 ipaddr) |
1413 | { |
1414 | struct ifreq ifr; |
1415 | struct sockaddr_in sin; |
1416 | |
1417 | memset(&ifr, 0, sizeof(ifr)); |
1418 | strcpy(ifr.ifr_name, tapif); |
1419 | |
1420 | /* Don't read these incantations. Just cut & paste them like I did! */ |
1421 | sin.sin_family = AF_INET; |
1422 | sin.sin_addr.s_addr = htonl(ipaddr); |
1423 | memcpy(&ifr.ifr_addr, &sin, sizeof(sin)); |
1424 | if (ioctl(fd, SIOCSIFADDR, &ifr) != 0) |
1425 | err(1, "Setting %s interface address", tapif); |
1426 | ifr.ifr_flags = IFF_UP; |
1427 | if (ioctl(fd, SIOCSIFFLAGS, &ifr) != 0) |
1428 | err(1, "Bringing interface %s up", tapif); |
1429 | } |
1430 | |
1431 | static int get_tun_device(char tapif[IFNAMSIZ]) |
1432 | { |
1433 | struct ifreq ifr; |
1434 | int netfd; |
1435 | |
1436 | /* Start with this zeroed. Messy but sure. */ |
1437 | memset(&ifr, 0, sizeof(ifr)); |
1438 | |
1439 | /* |
1440 | * We open the /dev/net/tun device and tell it we want a tap device. A |
1441 | * tap device is like a tun device, only somehow different. To tell |
1442 | * the truth, I completely blundered my way through this code, but it |
1443 | * works now! |
1444 | */ |
1445 | netfd = open_or_die("/dev/net/tun", O_RDWR); |
1446 | ifr.ifr_flags = IFF_TAP | IFF_NO_PI | IFF_VNET_HDR; |
1447 | strcpy(ifr.ifr_name, "tap%d"); |
1448 | if (ioctl(netfd, TUNSETIFF, &ifr) != 0) |
1449 | err(1, "configuring /dev/net/tun"); |
1450 | |
1451 | if (ioctl(netfd, TUNSETOFFLOAD, |
1452 | TUN_F_CSUM|TUN_F_TSO4|TUN_F_TSO6|TUN_F_TSO_ECN) != 0) |
1453 | err(1, "Could not set features for tun device"); |
1454 | |
1455 | /* |
1456 | * We don't need checksums calculated for packets coming in this |
1457 | * device: trust us! |
1458 | */ |
1459 | ioctl(netfd, TUNSETNOCSUM, 1); |
1460 | |
1461 | memcpy(tapif, ifr.ifr_name, IFNAMSIZ); |
1462 | return netfd; |
1463 | } |
1464 | |
1465 | /*L:195 |
1466 | * Our network is a Host<->Guest network. This can either use bridging or |
1467 | * routing, but the principle is the same: it uses the "tun" device to inject |
1468 | * packets into the Host as if they came in from a normal network card. We |
1469 | * just shunt packets between the Guest and the tun device. |
1470 | */ |
1471 | static void setup_tun_net(char *arg) |
1472 | { |
1473 | struct device *dev; |
1474 | struct net_info *net_info = malloc(sizeof(*net_info)); |
1475 | int ipfd; |
1476 | u32 ip = INADDR_ANY; |
1477 | bool bridging = false; |
1478 | char tapif[IFNAMSIZ], *p; |
1479 | struct virtio_net_config conf; |
1480 | |
1481 | net_info->tunfd = get_tun_device(tapif); |
1482 | |
1483 | /* First we create a new network device. */ |
1484 | dev = new_device("net", VIRTIO_ID_NET); |
1485 | dev->priv = net_info; |
1486 | |
1487 | /* Network devices need a recv and a send queue, just like console. */ |
1488 | add_virtqueue(dev, VIRTQUEUE_NUM, net_input); |
1489 | add_virtqueue(dev, VIRTQUEUE_NUM, net_output); |
1490 | |
1491 | /* |
1492 | * We need a socket to perform the magic network ioctls to bring up the |
1493 | * tap interface, connect to the bridge etc. Any socket will do! |
1494 | */ |
1495 | ipfd = socket(PF_INET, SOCK_DGRAM, IPPROTO_IP); |
1496 | if (ipfd < 0) |
1497 | err(1, "opening IP socket"); |
1498 | |
1499 | /* If the command line was --tunnet=bridge:<name> do bridging. */ |
1500 | if (!strncmp(BRIDGE_PFX, arg, strlen(BRIDGE_PFX))) { |
1501 | arg += strlen(BRIDGE_PFX); |
1502 | bridging = true; |
1503 | } |
1504 | |
1505 | /* A mac address may follow the bridge name or IP address */ |
1506 | p = strchr(arg, ':'); |
1507 | if (p) { |
1508 | str2mac(p+1, conf.mac); |
1509 | add_feature(dev, VIRTIO_NET_F_MAC); |
1510 | *p = '\0'; |
1511 | } |
1512 | |
1513 | /* arg is now either an IP address or a bridge name */ |
1514 | if (bridging) |
1515 | add_to_bridge(ipfd, tapif, arg); |
1516 | else |
1517 | ip = str2ip(arg); |
1518 | |
1519 | /* Set up the tun device. */ |
1520 | configure_device(ipfd, tapif, ip); |
1521 | |
1522 | /* Expect Guest to handle everything except UFO */ |
1523 | add_feature(dev, VIRTIO_NET_F_CSUM); |
1524 | add_feature(dev, VIRTIO_NET_F_GUEST_CSUM); |
1525 | add_feature(dev, VIRTIO_NET_F_GUEST_TSO4); |
1526 | add_feature(dev, VIRTIO_NET_F_GUEST_TSO6); |
1527 | add_feature(dev, VIRTIO_NET_F_GUEST_ECN); |
1528 | add_feature(dev, VIRTIO_NET_F_HOST_TSO4); |
1529 | add_feature(dev, VIRTIO_NET_F_HOST_TSO6); |
1530 | add_feature(dev, VIRTIO_NET_F_HOST_ECN); |
1531 | /* We handle indirect ring entries */ |
1532 | add_feature(dev, VIRTIO_RING_F_INDIRECT_DESC); |
1533 | set_config(dev, sizeof(conf), &conf); |
1534 | |
1535 | /* We don't need the socket any more; setup is done. */ |
1536 | close(ipfd); |
1537 | |
1538 | devices.device_num++; |
1539 | |
1540 | if (bridging) |
1541 | verbose("device %u: tun %s attached to bridge: %s\n", |
1542 | devices.device_num, tapif, arg); |
1543 | else |
1544 | verbose("device %u: tun %s: %s\n", |
1545 | devices.device_num, tapif, arg); |
1546 | } |
1547 | /*:*/ |
1548 | |
1549 | /* This hangs off device->priv. */ |
1550 | struct vblk_info { |
1551 | /* The size of the file. */ |
1552 | off64_t len; |
1553 | |
1554 | /* The file descriptor for the file. */ |
1555 | int fd; |
1556 | |
1557 | }; |
1558 | |
1559 | /*L:210 |
1560 | * The Disk |
1561 | * |
1562 | * The disk only has one virtqueue, so it only has one thread. It is really |
1563 | * simple: the Guest asks for a block number and we read or write that position |
1564 | * in the file. |
1565 | * |
1566 | * Before we serviced each virtqueue in a separate thread, that was unacceptably |
1567 | * slow: the Guest waits until the read is finished before running anything |
1568 | * else, even if it could have been doing useful work. |
1569 | * |
1570 | * We could have used async I/O, except it's reputed to suck so hard that |
1571 | * characters actually go missing from your code when you try to use it. |
1572 | */ |
1573 | static void blk_request(struct virtqueue *vq) |
1574 | { |
1575 | struct vblk_info *vblk = vq->dev->priv; |
1576 | unsigned int head, out_num, in_num, wlen; |
1577 | int ret, i; |
1578 | u8 *in; |
1579 | struct virtio_blk_outhdr out; |
1580 | struct iovec iov[vq->vring.num]; |
1581 | off64_t off; |
1582 | |
1583 | /* |
1584 | * Get the next request, where we normally wait. It triggers the |
1585 | * interrupt to acknowledge previously serviced requests (if any). |
1586 | */ |
1587 | head = wait_for_vq_desc(vq, iov, &out_num, &in_num); |
1588 | |
1589 | /* Copy the output header from the front of the iov (adjusts iov) */ |
1590 | iov_consume(iov, out_num, &out, sizeof(out)); |
1591 | |
1592 | /* Find and trim end of iov input array, for our status byte. */ |
1593 | in = NULL; |
1594 | for (i = out_num + in_num - 1; i >= out_num; i--) { |
1595 | if (iov[i].iov_len > 0) { |
1596 | in = iov[i].iov_base + iov[i].iov_len - 1; |
1597 | iov[i].iov_len--; |
1598 | break; |
1599 | } |
1600 | } |
1601 | if (!in) |
1602 | errx(1, "Bad virtblk cmd with no room for status"); |
1603 | |
1604 | /* |
1605 | * For historical reasons, block operations are expressed in 512 byte |
1606 | * "sectors". |
1607 | */ |
1608 | off = out.sector * 512; |
1609 | |
1610 | /* |
1611 | * In general the virtio block driver is allowed to try SCSI commands. |
1612 | * It'd be nice if we supported eject, for example, but we don't. |
1613 | */ |
1614 | if (out.type & VIRTIO_BLK_T_SCSI_CMD) { |
1615 | fprintf(stderr, "Scsi commands unsupported\n"); |
1616 | *in = VIRTIO_BLK_S_UNSUPP; |
1617 | wlen = sizeof(*in); |
1618 | } else if (out.type & VIRTIO_BLK_T_OUT) { |
1619 | /* |
1620 | * Write |
1621 | * |
1622 | * Move to the right location in the block file. This can fail |
1623 | * if they try to write past end. |
1624 | */ |
1625 | if (lseek64(vblk->fd, off, SEEK_SET) != off) |
1626 | err(1, "Bad seek to sector %llu", out.sector); |
1627 | |
1628 | ret = writev(vblk->fd, iov, out_num); |
1629 | verbose("WRITE to sector %llu: %i\n", out.sector, ret); |
1630 | |
1631 | /* |
1632 | * Grr... Now we know how long the descriptor they sent was, we |
1633 | * make sure they didn't try to write over the end of the block |
1634 | * file (possibly extending it). |
1635 | */ |
1636 | if (ret > 0 && off + ret > vblk->len) { |
1637 | /* Trim it back to the correct length */ |
1638 | ftruncate64(vblk->fd, vblk->len); |
1639 | /* Die, bad Guest, die. */ |
1640 | errx(1, "Write past end %llu+%u", off, ret); |
1641 | } |
1642 | |
1643 | wlen = sizeof(*in); |
1644 | *in = (ret >= 0 ? VIRTIO_BLK_S_OK : VIRTIO_BLK_S_IOERR); |
1645 | } else if (out.type & VIRTIO_BLK_T_FLUSH) { |
1646 | /* Flush */ |
1647 | ret = fdatasync(vblk->fd); |
1648 | verbose("FLUSH fdatasync: %i\n", ret); |
1649 | wlen = sizeof(*in); |
1650 | *in = (ret >= 0 ? VIRTIO_BLK_S_OK : VIRTIO_BLK_S_IOERR); |
1651 | } else { |
1652 | /* |
1653 | * Read |
1654 | * |
1655 | * Move to the right location in the block file. This can fail |
1656 | * if they try to read past end. |
1657 | */ |
1658 | if (lseek64(vblk->fd, off, SEEK_SET) != off) |
1659 | err(1, "Bad seek to sector %llu", out.sector); |
1660 | |
1661 | ret = readv(vblk->fd, iov + out_num, in_num); |
1662 | if (ret >= 0) { |
1663 | wlen = sizeof(*in) + ret; |
1664 | *in = VIRTIO_BLK_S_OK; |
1665 | } else { |
1666 | wlen = sizeof(*in); |
1667 | *in = VIRTIO_BLK_S_IOERR; |
1668 | } |
1669 | } |
1670 | |
1671 | /* Finished that request. */ |
1672 | add_used(vq, head, wlen); |
1673 | } |
1674 | |
1675 | /*L:198 This actually sets up a virtual block device. */ |
1676 | static void setup_block_file(const char *filename) |
1677 | { |
1678 | struct device *dev; |
1679 | struct vblk_info *vblk; |
1680 | struct virtio_blk_config conf; |
1681 | |
1682 | /* Creat the device. */ |
1683 | dev = new_device("block", VIRTIO_ID_BLOCK); |
1684 | |
1685 | /* The device has one virtqueue, where the Guest places requests. */ |
1686 | add_virtqueue(dev, VIRTQUEUE_NUM, blk_request); |
1687 | |
1688 | /* Allocate the room for our own bookkeeping */ |
1689 | vblk = dev->priv = malloc(sizeof(*vblk)); |
1690 | |
1691 | /* First we open the file and store the length. */ |
1692 | vblk->fd = open_or_die(filename, O_RDWR|O_LARGEFILE); |
1693 | vblk->len = lseek64(vblk->fd, 0, SEEK_END); |
1694 | |
1695 | /* We support FLUSH. */ |
1696 | add_feature(dev, VIRTIO_BLK_F_FLUSH); |
1697 | |
1698 | /* Tell Guest how many sectors this device has. */ |
1699 | conf.capacity = cpu_to_le64(vblk->len / 512); |
1700 | |
1701 | /* |
1702 | * Tell Guest not to put in too many descriptors at once: two are used |
1703 | * for the in and out elements. |
1704 | */ |
1705 | add_feature(dev, VIRTIO_BLK_F_SEG_MAX); |
1706 | conf.seg_max = cpu_to_le32(VIRTQUEUE_NUM - 2); |
1707 | |
1708 | /* Don't try to put whole struct: we have 8 bit limit. */ |
1709 | set_config(dev, offsetof(struct virtio_blk_config, geometry), &conf); |
1710 | |
1711 | verbose("device %u: virtblock %llu sectors\n", |
1712 | ++devices.device_num, le64_to_cpu(conf.capacity)); |
1713 | } |
1714 | |
1715 | /*L:211 |
1716 | * Our random number generator device reads from /dev/random into the Guest's |
1717 | * input buffers. The usual case is that the Guest doesn't want random numbers |
1718 | * and so has no buffers although /dev/random is still readable, whereas |
1719 | * console is the reverse. |
1720 | * |
1721 | * The same logic applies, however. |
1722 | */ |
1723 | struct rng_info { |
1724 | int rfd; |
1725 | }; |
1726 | |
1727 | static void rng_input(struct virtqueue *vq) |
1728 | { |
1729 | int len; |
1730 | unsigned int head, in_num, out_num, totlen = 0; |
1731 | struct rng_info *rng_info = vq->dev->priv; |
1732 | struct iovec iov[vq->vring.num]; |
1733 | |
1734 | /* First we need a buffer from the Guests's virtqueue. */ |
1735 | head = wait_for_vq_desc(vq, iov, &out_num, &in_num); |
1736 | if (out_num) |
1737 | errx(1, "Output buffers in rng?"); |
1738 | |
1739 | /* |
1740 | * Just like the console write, we loop to cover the whole iovec. |
1741 | * In this case, short reads actually happen quite a bit. |
1742 | */ |
1743 | while (!iov_empty(iov, in_num)) { |
1744 | len = readv(rng_info->rfd, iov, in_num); |
1745 | if (len <= 0) |
1746 | err(1, "Read from /dev/random gave %i", len); |
1747 | iov_consume(iov, in_num, NULL, len); |
1748 | totlen += len; |
1749 | } |
1750 | |
1751 | /* Tell the Guest about the new input. */ |
1752 | add_used(vq, head, totlen); |
1753 | } |
1754 | |
1755 | /*L:199 |
1756 | * This creates a "hardware" random number device for the Guest. |
1757 | */ |
1758 | static void setup_rng(void) |
1759 | { |
1760 | struct device *dev; |
1761 | struct rng_info *rng_info = malloc(sizeof(*rng_info)); |
1762 | |
1763 | /* Our device's privat info simply contains the /dev/random fd. */ |
1764 | rng_info->rfd = open_or_die("/dev/random", O_RDONLY); |
1765 | |
1766 | /* Create the new device. */ |
1767 | dev = new_device("rng", VIRTIO_ID_RNG); |
1768 | dev->priv = rng_info; |
1769 | |
1770 | /* The device has one virtqueue, where the Guest places inbufs. */ |
1771 | add_virtqueue(dev, VIRTQUEUE_NUM, rng_input); |
1772 | |
1773 | verbose("device %u: rng\n", devices.device_num++); |
1774 | } |
1775 | /* That's the end of device setup. */ |
1776 | |
1777 | /*L:230 Reboot is pretty easy: clean up and exec() the Launcher afresh. */ |
1778 | static void __attribute__((noreturn)) restart_guest(void) |
1779 | { |
1780 | unsigned int i; |
1781 | |
1782 | /* |
1783 | * Since we don't track all open fds, we simply close everything beyond |
1784 | * stderr. |
1785 | */ |
1786 | for (i = 3; i < FD_SETSIZE; i++) |
1787 | close(i); |
1788 | |
1789 | /* Reset all the devices (kills all threads). */ |
1790 | cleanup_devices(); |
1791 | |
1792 | execv(main_args[0], main_args); |
1793 | err(1, "Could not exec %s", main_args[0]); |
1794 | } |
1795 | |
1796 | /*L:220 |
1797 | * Finally we reach the core of the Launcher which runs the Guest, serves |
1798 | * its input and output, and finally, lays it to rest. |
1799 | */ |
1800 | static void __attribute__((noreturn)) run_guest(void) |
1801 | { |
1802 | for (;;) { |
1803 | unsigned long notify_addr; |
1804 | int readval; |
1805 | |
1806 | /* We read from the /dev/lguest device to run the Guest. */ |
1807 | readval = pread(lguest_fd, ¬ify_addr, |
1808 | sizeof(notify_addr), cpu_id); |
1809 | |
1810 | /* One unsigned long means the Guest did HCALL_NOTIFY */ |
1811 | if (readval == sizeof(notify_addr)) { |
1812 | verbose("Notify on address %#lx\n", notify_addr); |
1813 | handle_output(notify_addr); |
1814 | /* ENOENT means the Guest died. Reading tells us why. */ |
1815 | } else if (errno == ENOENT) { |
1816 | char reason[1024] = { 0 }; |
1817 | pread(lguest_fd, reason, sizeof(reason)-1, cpu_id); |
1818 | errx(1, "%s", reason); |
1819 | /* ERESTART means that we need to reboot the guest */ |
1820 | } else if (errno == ERESTART) { |
1821 | restart_guest(); |
1822 | /* Anything else means a bug or incompatible change. */ |
1823 | } else |
1824 | err(1, "Running guest failed"); |
1825 | } |
1826 | } |
1827 | /*L:240 |
1828 | * This is the end of the Launcher. The good news: we are over halfway |
1829 | * through! The bad news: the most fiendish part of the code still lies ahead |
1830 | * of us. |
1831 | * |
1832 | * Are you ready? Take a deep breath and join me in the core of the Host, in |
1833 | * "make Host". |
1834 | :*/ |
1835 | |
1836 | static struct option opts[] = { |
1837 | { "verbose", 0, NULL, 'v' }, |
1838 | { "tunnet", 1, NULL, 't' }, |
1839 | { "block", 1, NULL, 'b' }, |
1840 | { "rng", 0, NULL, 'r' }, |
1841 | { "initrd", 1, NULL, 'i' }, |
1842 | { "username", 1, NULL, 'u' }, |
1843 | { "chroot", 1, NULL, 'c' }, |
1844 | { NULL }, |
1845 | }; |
1846 | static void usage(void) |
1847 | { |
1848 | errx(1, "Usage: lguest [--verbose] " |
1849 | "[--tunnet=(<ipaddr>:<macaddr>|bridge:<bridgename>:<macaddr>)\n" |
1850 | "|--block=<filename>|--initrd=<filename>]...\n" |
1851 | "<mem-in-mb> vmlinux [args...]"); |
1852 | } |
1853 | |
1854 | /*L:105 The main routine is where the real work begins: */ |
1855 | int main(int argc, char *argv[]) |
1856 | { |
1857 | /* Memory, code startpoint and size of the (optional) initrd. */ |
1858 | unsigned long mem = 0, start, initrd_size = 0; |
1859 | /* Two temporaries. */ |
1860 | int i, c; |
1861 | /* The boot information for the Guest. */ |
1862 | struct boot_params *boot; |
1863 | /* If they specify an initrd file to load. */ |
1864 | const char *initrd_name = NULL; |
1865 | |
1866 | /* Password structure for initgroups/setres[gu]id */ |
1867 | struct passwd *user_details = NULL; |
1868 | |
1869 | /* Directory to chroot to */ |
1870 | char *chroot_path = NULL; |
1871 | |
1872 | /* Save the args: we "reboot" by execing ourselves again. */ |
1873 | main_args = argv; |
1874 | |
1875 | /* |
1876 | * First we initialize the device list. We keep a pointer to the last |
1877 | * device, and the next interrupt number to use for devices (1: |
1878 | * remember that 0 is used by the timer). |
1879 | */ |
1880 | devices.lastdev = NULL; |
1881 | devices.next_irq = 1; |
1882 | |
1883 | /* We're CPU 0. In fact, that's the only CPU possible right now. */ |
1884 | cpu_id = 0; |
1885 | |
1886 | /* |
1887 | * We need to know how much memory so we can set up the device |
1888 | * descriptor and memory pages for the devices as we parse the command |
1889 | * line. So we quickly look through the arguments to find the amount |
1890 | * of memory now. |
1891 | */ |
1892 | for (i = 1; i < argc; i++) { |
1893 | if (argv[i][0] != '-') { |
1894 | mem = atoi(argv[i]) * 1024 * 1024; |
1895 | /* |
1896 | * We start by mapping anonymous pages over all of |
1897 | * guest-physical memory range. This fills it with 0, |
1898 | * and ensures that the Guest won't be killed when it |
1899 | * tries to access it. |
1900 | */ |
1901 | guest_base = map_zeroed_pages(mem / getpagesize() |
1902 | + DEVICE_PAGES); |
1903 | guest_limit = mem; |
1904 | guest_max = mem + DEVICE_PAGES*getpagesize(); |
1905 | devices.descpage = get_pages(1); |
1906 | break; |
1907 | } |
1908 | } |
1909 | |
1910 | /* The options are fairly straight-forward */ |
1911 | while ((c = getopt_long(argc, argv, "v", opts, NULL)) != EOF) { |
1912 | switch (c) { |
1913 | case 'v': |
1914 | verbose = true; |
1915 | break; |
1916 | case 't': |
1917 | setup_tun_net(optarg); |
1918 | break; |
1919 | case 'b': |
1920 | setup_block_file(optarg); |
1921 | break; |
1922 | case 'r': |
1923 | setup_rng(); |
1924 | break; |
1925 | case 'i': |
1926 | initrd_name = optarg; |
1927 | break; |
1928 | case 'u': |
1929 | user_details = getpwnam(optarg); |
1930 | if (!user_details) |
1931 | err(1, "getpwnam failed, incorrect username?"); |
1932 | break; |
1933 | case 'c': |
1934 | chroot_path = optarg; |
1935 | break; |
1936 | default: |
1937 | warnx("Unknown argument %s", argv[optind]); |
1938 | usage(); |
1939 | } |
1940 | } |
1941 | /* |
1942 | * After the other arguments we expect memory and kernel image name, |
1943 | * followed by command line arguments for the kernel. |
1944 | */ |
1945 | if (optind + 2 > argc) |
1946 | usage(); |
1947 | |
1948 | verbose("Guest base is at %p\n", guest_base); |
1949 | |
1950 | /* We always have a console device */ |
1951 | setup_console(); |
1952 | |
1953 | /* Now we load the kernel */ |
1954 | start = load_kernel(open_or_die(argv[optind+1], O_RDONLY)); |
1955 | |
1956 | /* Boot information is stashed at physical address 0 */ |
1957 | boot = from_guest_phys(0); |
1958 | |
1959 | /* Map the initrd image if requested (at top of physical memory) */ |
1960 | if (initrd_name) { |
1961 | initrd_size = load_initrd(initrd_name, mem); |
1962 | /* |
1963 | * These are the location in the Linux boot header where the |
1964 | * start and size of the initrd are expected to be found. |
1965 | */ |
1966 | boot->hdr.ramdisk_image = mem - initrd_size; |
1967 | boot->hdr.ramdisk_size = initrd_size; |
1968 | /* The bootloader type 0xFF means "unknown"; that's OK. */ |
1969 | boot->hdr.type_of_loader = 0xFF; |
1970 | } |
1971 | |
1972 | /* |
1973 | * The Linux boot header contains an "E820" memory map: ours is a |
1974 | * simple, single region. |
1975 | */ |
1976 | boot->e820_entries = 1; |
1977 | boot->e820_map[0] = ((struct e820entry) { 0, mem, E820_RAM }); |
1978 | /* |
1979 | * The boot header contains a command line pointer: we put the command |
1980 | * line after the boot header. |
1981 | */ |
1982 | boot->hdr.cmd_line_ptr = to_guest_phys(boot + 1); |
1983 | /* We use a simple helper to copy the arguments separated by spaces. */ |
1984 | concat((char *)(boot + 1), argv+optind+2); |
1985 | |
1986 | /* Set kernel alignment to 16M (CONFIG_PHYSICAL_ALIGN) */ |
1987 | boot->hdr.kernel_alignment = 0x1000000; |
1988 | |
1989 | /* Boot protocol version: 2.07 supports the fields for lguest. */ |
1990 | boot->hdr.version = 0x207; |
1991 | |
1992 | /* The hardware_subarch value of "1" tells the Guest it's an lguest. */ |
1993 | boot->hdr.hardware_subarch = 1; |
1994 | |
1995 | /* Tell the entry path not to try to reload segment registers. */ |
1996 | boot->hdr.loadflags |= KEEP_SEGMENTS; |
1997 | |
1998 | /* We tell the kernel to initialize the Guest. */ |
1999 | tell_kernel(start); |
2000 | |
2001 | /* Ensure that we terminate if a device-servicing child dies. */ |
2002 | signal(SIGCHLD, kill_launcher); |
2003 | |
2004 | /* If we exit via err(), this kills all the threads, restores tty. */ |
2005 | atexit(cleanup_devices); |
2006 | |
2007 | /* If requested, chroot to a directory */ |
2008 | if (chroot_path) { |
2009 | if (chroot(chroot_path) != 0) |
2010 | err(1, "chroot(\"%s\") failed", chroot_path); |
2011 | |
2012 | if (chdir("/") != 0) |
2013 | err(1, "chdir(\"/\") failed"); |
2014 | |
2015 | verbose("chroot done\n"); |
2016 | } |
2017 | |
2018 | /* If requested, drop privileges */ |
2019 | if (user_details) { |
2020 | uid_t u; |
2021 | gid_t g; |
2022 | |
2023 | u = user_details->pw_uid; |
2024 | g = user_details->pw_gid; |
2025 | |
2026 | if (initgroups(user_details->pw_name, g) != 0) |
2027 | err(1, "initgroups failed"); |
2028 | |
2029 | if (setresgid(g, g, g) != 0) |
2030 | err(1, "setresgid failed"); |
2031 | |
2032 | if (setresuid(u, u, u) != 0) |
2033 | err(1, "setresuid failed"); |
2034 | |
2035 | verbose("Dropping privileges completed\n"); |
2036 | } |
2037 | |
2038 | /* Finally, run the Guest. This doesn't return. */ |
2039 | run_guest(); |
2040 | } |
2041 | /*:*/ |
2042 | |
2043 | /*M:999 |
2044 | * Mastery is done: you now know everything I do. |
2045 | * |
2046 | * But surely you have seen code, features and bugs in your wanderings which |
2047 | * you now yearn to attack? That is the real game, and I look forward to you |
2048 | * patching and forking lguest into the Your-Name-Here-visor. |
2049 | * |
2050 | * Farewell, and good coding! |
2051 | * Rusty Russell. |
2052 | */ |
2053 |
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Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
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