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 42 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 PAGE_PRESENT 0x7 /* Present, RW, Execute */ |
69 | #define BRIDGE_PFX "bridge:" |
70 | #ifndef SIOCBRADDIF |
71 | #define SIOCBRADDIF 0x89a2 /* add interface to bridge */ |
72 | #endif |
73 | /* We can have up to 256 pages for devices. */ |
74 | #define DEVICE_PAGES 256 |
75 | /* This will occupy 3 pages: it must be a power of 2. */ |
76 | #define VIRTQUEUE_NUM 256 |
77 | |
78 | /*L:120 |
79 | * verbose is both a global flag and a macro. The C preprocessor allows |
80 | * this, and although I wouldn't recommend it, it works quite nicely here. |
81 | */ |
82 | static bool verbose; |
83 | #define verbose(args...) \ |
84 | do { if (verbose) printf(args); } while(0) |
85 | /*:*/ |
86 | |
87 | /* The pointer to the start of guest memory. */ |
88 | static void *guest_base; |
89 | /* The maximum guest physical address allowed, and maximum possible. */ |
90 | static unsigned long guest_limit, guest_max; |
91 | /* The /dev/lguest file descriptor. */ |
92 | static int lguest_fd; |
93 | |
94 | /* a per-cpu variable indicating whose vcpu is currently running */ |
95 | static unsigned int __thread cpu_id; |
96 | |
97 | /* This is our list of devices. */ |
98 | struct device_list { |
99 | /* Counter to assign interrupt numbers. */ |
100 | unsigned int next_irq; |
101 | |
102 | /* Counter to print out convenient device numbers. */ |
103 | unsigned int device_num; |
104 | |
105 | /* The descriptor page for the devices. */ |
106 | u8 *descpage; |
107 | |
108 | /* A single linked list of devices. */ |
109 | struct device *dev; |
110 | /* And a pointer to the last device for easy append. */ |
111 | struct device *lastdev; |
112 | }; |
113 | |
114 | /* The list of Guest devices, based on command line arguments. */ |
115 | static struct device_list devices; |
116 | |
117 | /* The device structure describes a single device. */ |
118 | struct device { |
119 | /* The linked-list pointer. */ |
120 | struct device *next; |
121 | |
122 | /* The device's descriptor, as mapped into the Guest. */ |
123 | struct lguest_device_desc *desc; |
124 | |
125 | /* We can't trust desc values once Guest has booted: we use these. */ |
126 | unsigned int feature_len; |
127 | unsigned int num_vq; |
128 | |
129 | /* The name of this device, for --verbose. */ |
130 | const char *name; |
131 | |
132 | /* Any queues attached to this device */ |
133 | struct virtqueue *vq; |
134 | |
135 | /* Is it operational */ |
136 | bool running; |
137 | |
138 | /* Does Guest want an intrrupt on empty? */ |
139 | bool irq_on_empty; |
140 | |
141 | /* Device-specific data. */ |
142 | void *priv; |
143 | }; |
144 | |
145 | /* The virtqueue structure describes a queue attached to a device. */ |
146 | struct virtqueue { |
147 | struct virtqueue *next; |
148 | |
149 | /* Which device owns me. */ |
150 | struct device *dev; |
151 | |
152 | /* The configuration for this queue. */ |
153 | struct lguest_vqconfig config; |
154 | |
155 | /* The actual ring of buffers. */ |
156 | struct vring vring; |
157 | |
158 | /* Last available index we saw. */ |
159 | u16 last_avail_idx; |
160 | |
161 | /* How many are used since we sent last irq? */ |
162 | unsigned int pending_used; |
163 | |
164 | /* Eventfd where Guest notifications arrive. */ |
165 | int eventfd; |
166 | |
167 | /* Function for the thread which is servicing this virtqueue. */ |
168 | void (*service)(struct virtqueue *vq); |
169 | pid_t thread; |
170 | }; |
171 | |
172 | /* Remember the arguments to the program so we can "reboot" */ |
173 | static char **main_args; |
174 | |
175 | /* The original tty settings to restore on exit. */ |
176 | static struct termios orig_term; |
177 | |
178 | /* |
179 | * We have to be careful with barriers: our devices are all run in separate |
180 | * threads and so we need to make sure that changes visible to the Guest happen |
181 | * in precise order. |
182 | */ |
183 | #define wmb() __asm__ __volatile__("" : : : "memory") |
184 | #define mb() __asm__ __volatile__("" : : : "memory") |
185 | |
186 | /* |
187 | * Convert an iovec element to the given type. |
188 | * |
189 | * This is a fairly ugly trick: we need to know the size of the type and |
190 | * alignment requirement to check the pointer is kosher. It's also nice to |
191 | * have the name of the type in case we report failure. |
192 | * |
193 | * Typing those three things all the time is cumbersome and error prone, so we |
194 | * have a macro which sets them all up and passes to the real function. |
195 | */ |
196 | #define convert(iov, type) \ |
197 | ((type *)_convert((iov), sizeof(type), __alignof__(type), #type)) |
198 | |
199 | static void *_convert(struct iovec *iov, size_t size, size_t align, |
200 | const char *name) |
201 | { |
202 | if (iov->iov_len != size) |
203 | errx(1, "Bad iovec size %zu for %s", iov->iov_len, name); |
204 | if ((unsigned long)iov->iov_base % align != 0) |
205 | errx(1, "Bad alignment %p for %s", iov->iov_base, name); |
206 | return iov->iov_base; |
207 | } |
208 | |
209 | /* Wrapper for the last available index. Makes it easier to change. */ |
210 | #define lg_last_avail(vq) ((vq)->last_avail_idx) |
211 | |
212 | /* |
213 | * The virtio configuration space is defined to be little-endian. x86 is |
214 | * little-endian too, but it's nice to be explicit so we have these helpers. |
215 | */ |
216 | #define cpu_to_le16(v16) (v16) |
217 | #define cpu_to_le32(v32) (v32) |
218 | #define cpu_to_le64(v64) (v64) |
219 | #define le16_to_cpu(v16) (v16) |
220 | #define le32_to_cpu(v32) (v32) |
221 | #define le64_to_cpu(v64) (v64) |
222 | |
223 | /* Is this iovec empty? */ |
224 | static bool iov_empty(const struct iovec iov[], unsigned int num_iov) |
225 | { |
226 | unsigned int i; |
227 | |
228 | for (i = 0; i < num_iov; i++) |
229 | if (iov[i].iov_len) |
230 | return false; |
231 | return true; |
232 | } |
233 | |
234 | /* Take len bytes from the front of this iovec. */ |
235 | static void iov_consume(struct iovec iov[], unsigned num_iov, unsigned len) |
236 | { |
237 | unsigned int i; |
238 | |
239 | for (i = 0; i < num_iov; i++) { |
240 | unsigned int used; |
241 | |
242 | used = iov[i].iov_len < len ? iov[i].iov_len : len; |
243 | iov[i].iov_base += used; |
244 | iov[i].iov_len -= used; |
245 | len -= used; |
246 | } |
247 | assert(len == 0); |
248 | } |
249 | |
250 | /* The device virtqueue descriptors are followed by feature bitmasks. */ |
251 | static u8 *get_feature_bits(struct device *dev) |
252 | { |
253 | return (u8 *)(dev->desc + 1) |
254 | + dev->num_vq * sizeof(struct lguest_vqconfig); |
255 | } |
256 | |
257 | /*L:100 |
258 | * The Launcher code itself takes us out into userspace, that scary place where |
259 | * pointers run wild and free! Unfortunately, like most userspace programs, |
260 | * it's quite boring (which is why everyone likes to hack on the kernel!). |
261 | * Perhaps if you make up an Lguest Drinking Game at this point, it will get |
262 | * you through this section. Or, maybe not. |
263 | * |
264 | * The Launcher sets up a big chunk of memory to be the Guest's "physical" |
265 | * memory and stores it in "guest_base". In other words, Guest physical == |
266 | * Launcher virtual with an offset. |
267 | * |
268 | * This can be tough to get your head around, but usually it just means that we |
269 | * use these trivial conversion functions when the Guest gives us its |
270 | * "physical" addresses: |
271 | */ |
272 | static void *from_guest_phys(unsigned long addr) |
273 | { |
274 | return guest_base + addr; |
275 | } |
276 | |
277 | static unsigned long to_guest_phys(const void *addr) |
278 | { |
279 | return (addr - guest_base); |
280 | } |
281 | |
282 | /*L:130 |
283 | * Loading the Kernel. |
284 | * |
285 | * We start with couple of simple helper routines. open_or_die() avoids |
286 | * error-checking code cluttering the callers: |
287 | */ |
288 | static int open_or_die(const char *name, int flags) |
289 | { |
290 | int fd = open(name, flags); |
291 | if (fd < 0) |
292 | err(1, "Failed to open %s", name); |
293 | return fd; |
294 | } |
295 | |
296 | /* map_zeroed_pages() takes a number of pages. */ |
297 | static void *map_zeroed_pages(unsigned int num) |
298 | { |
299 | int fd = open_or_die("/dev/zero", O_RDONLY); |
300 | void *addr; |
301 | |
302 | /* |
303 | * We use a private mapping (ie. if we write to the page, it will be |
304 | * copied). We allocate an extra two pages PROT_NONE to act as guard |
305 | * pages against read/write attempts that exceed allocated space. |
306 | */ |
307 | addr = mmap(NULL, getpagesize() * (num+2), |
308 | PROT_NONE, MAP_PRIVATE, fd, 0); |
309 | |
310 | if (addr == MAP_FAILED) |
311 | err(1, "Mmapping %u pages of /dev/zero", num); |
312 | |
313 | if (mprotect(addr + getpagesize(), getpagesize() * num, |
314 | PROT_READ|PROT_WRITE) == -1) |
315 | err(1, "mprotect rw %u pages failed", num); |
316 | |
317 | /* |
318 | * One neat mmap feature is that you can close the fd, and it |
319 | * stays mapped. |
320 | */ |
321 | close(fd); |
322 | |
323 | /* Return address after PROT_NONE page */ |
324 | return addr + getpagesize(); |
325 | } |
326 | |
327 | /* Get some more pages for a device. */ |
328 | static void *get_pages(unsigned int num) |
329 | { |
330 | void *addr = from_guest_phys(guest_limit); |
331 | |
332 | guest_limit += num * getpagesize(); |
333 | if (guest_limit > guest_max) |
334 | errx(1, "Not enough memory for devices"); |
335 | return addr; |
336 | } |
337 | |
338 | /* |
339 | * This routine is used to load the kernel or initrd. It tries mmap, but if |
340 | * that fails (Plan 9's kernel file isn't nicely aligned on page boundaries), |
341 | * it falls back to reading the memory in. |
342 | */ |
343 | static void map_at(int fd, void *addr, unsigned long offset, unsigned long len) |
344 | { |
345 | ssize_t r; |
346 | |
347 | /* |
348 | * We map writable even though for some segments are marked read-only. |
349 | * The kernel really wants to be writable: it patches its own |
350 | * instructions. |
351 | * |
352 | * MAP_PRIVATE means that the page won't be copied until a write is |
353 | * done to it. This allows us to share untouched memory between |
354 | * Guests. |
355 | */ |
356 | if (mmap(addr, len, PROT_READ|PROT_WRITE, |
357 | MAP_FIXED|MAP_PRIVATE, fd, offset) != MAP_FAILED) |
358 | return; |
359 | |
360 | /* pread does a seek and a read in one shot: saves a few lines. */ |
361 | r = pread(fd, addr, len, offset); |
362 | if (r != len) |
363 | err(1, "Reading offset %lu len %lu gave %zi", offset, len, r); |
364 | } |
365 | |
366 | /* |
367 | * This routine takes an open vmlinux image, which is in ELF, and maps it into |
368 | * the Guest memory. ELF = Embedded Linking Format, which is the format used |
369 | * by all modern binaries on Linux including the kernel. |
370 | * |
371 | * The ELF headers give *two* addresses: a physical address, and a virtual |
372 | * address. We use the physical address; the Guest will map itself to the |
373 | * virtual address. |
374 | * |
375 | * We return the starting address. |
376 | */ |
377 | static unsigned long map_elf(int elf_fd, const Elf32_Ehdr *ehdr) |
378 | { |
379 | Elf32_Phdr phdr[ehdr->e_phnum]; |
380 | unsigned int i; |
381 | |
382 | /* |
383 | * Sanity checks on the main ELF header: an x86 executable with a |
384 | * reasonable number of correctly-sized program headers. |
385 | */ |
386 | if (ehdr->e_type != ET_EXEC |
387 | || ehdr->e_machine != EM_386 |
388 | || ehdr->e_phentsize != sizeof(Elf32_Phdr) |
389 | || ehdr->e_phnum < 1 || ehdr->e_phnum > 65536U/sizeof(Elf32_Phdr)) |
390 | errx(1, "Malformed elf header"); |
391 | |
392 | /* |
393 | * An ELF executable contains an ELF header and a number of "program" |
394 | * headers which indicate which parts ("segments") of the program to |
395 | * load where. |
396 | */ |
397 | |
398 | /* We read in all the program headers at once: */ |
399 | if (lseek(elf_fd, ehdr->e_phoff, SEEK_SET) < 0) |
400 | err(1, "Seeking to program headers"); |
401 | if (read(elf_fd, phdr, sizeof(phdr)) != sizeof(phdr)) |
402 | err(1, "Reading program headers"); |
403 | |
404 | /* |
405 | * Try all the headers: there are usually only three. A read-only one, |
406 | * a read-write one, and a "note" section which we don't load. |
407 | */ |
408 | for (i = 0; i < ehdr->e_phnum; i++) { |
409 | /* If this isn't a loadable segment, we ignore it */ |
410 | if (phdr[i].p_type != PT_LOAD) |
411 | continue; |
412 | |
413 | verbose("Section %i: size %i addr %p\n", |
414 | i, phdr[i].p_memsz, (void *)phdr[i].p_paddr); |
415 | |
416 | /* We map this section of the file at its physical address. */ |
417 | map_at(elf_fd, from_guest_phys(phdr[i].p_paddr), |
418 | phdr[i].p_offset, phdr[i].p_filesz); |
419 | } |
420 | |
421 | /* The entry point is given in the ELF header. */ |
422 | return ehdr->e_entry; |
423 | } |
424 | |
425 | /*L:150 |
426 | * A bzImage, unlike an ELF file, is not meant to be loaded. You're supposed |
427 | * to jump into it and it will unpack itself. We used to have to perform some |
428 | * hairy magic because the unpacking code scared me. |
429 | * |
430 | * Fortunately, Jeremy Fitzhardinge convinced me it wasn't that hard and wrote |
431 | * a small patch to jump over the tricky bits in the Guest, so now we just read |
432 | * the funky header so we know where in the file to load, and away we go! |
433 | */ |
434 | static unsigned long load_bzimage(int fd) |
435 | { |
436 | struct boot_params boot; |
437 | int r; |
438 | /* Modern bzImages get loaded at 1M. */ |
439 | void *p = from_guest_phys(0x100000); |
440 | |
441 | /* |
442 | * Go back to the start of the file and read the header. It should be |
443 | * a Linux boot header (see Documentation/x86/i386/boot.txt) |
444 | */ |
445 | lseek(fd, 0, SEEK_SET); |
446 | read(fd, &boot, sizeof(boot)); |
447 | |
448 | /* Inside the setup_hdr, we expect the magic "HdrS" */ |
449 | if (memcmp(&boot.hdr.header, "HdrS", 4) != 0) |
450 | errx(1, "This doesn't look like a bzImage to me"); |
451 | |
452 | /* Skip over the extra sectors of the header. */ |
453 | lseek(fd, (boot.hdr.setup_sects+1) * 512, SEEK_SET); |
454 | |
455 | /* Now read everything into memory. in nice big chunks. */ |
456 | while ((r = read(fd, p, 65536)) > 0) |
457 | p += r; |
458 | |
459 | /* Finally, code32_start tells us where to enter the kernel. */ |
460 | return boot.hdr.code32_start; |
461 | } |
462 | |
463 | /*L:140 |
464 | * Loading the kernel is easy when it's a "vmlinux", but most kernels |
465 | * come wrapped up in the self-decompressing "bzImage" format. With a little |
466 | * work, we can load those, too. |
467 | */ |
468 | static unsigned long load_kernel(int fd) |
469 | { |
470 | Elf32_Ehdr hdr; |
471 | |
472 | /* Read in the first few bytes. */ |
473 | if (read(fd, &hdr, sizeof(hdr)) != sizeof(hdr)) |
474 | err(1, "Reading kernel"); |
475 | |
476 | /* If it's an ELF file, it starts with "\177ELF" */ |
477 | if (memcmp(hdr.e_ident, ELFMAG, SELFMAG) == 0) |
478 | return map_elf(fd, &hdr); |
479 | |
480 | /* Otherwise we assume it's a bzImage, and try to load it. */ |
481 | return load_bzimage(fd); |
482 | } |
483 | |
484 | /* |
485 | * This is a trivial little helper to align pages. Andi Kleen hated it because |
486 | * it calls getpagesize() twice: "it's dumb code." |
487 | * |
488 | * Kernel guys get really het up about optimization, even when it's not |
489 | * necessary. I leave this code as a reaction against that. |
490 | */ |
491 | static inline unsigned long page_align(unsigned long addr) |
492 | { |
493 | /* Add upwards and truncate downwards. */ |
494 | return ((addr + getpagesize()-1) & ~(getpagesize()-1)); |
495 | } |
496 | |
497 | /*L:180 |
498 | * An "initial ram disk" is a disk image loaded into memory along with the |
499 | * kernel which the kernel can use to boot from without needing any drivers. |
500 | * Most distributions now use this as standard: the initrd contains the code to |
501 | * load the appropriate driver modules for the current machine. |
502 | * |
503 | * Importantly, James Morris works for RedHat, and Fedora uses initrds for its |
504 | * kernels. He sent me this (and tells me when I break it). |
505 | */ |
506 | static unsigned long load_initrd(const char *name, unsigned long mem) |
507 | { |
508 | int ifd; |
509 | struct stat st; |
510 | unsigned long len; |
511 | |
512 | ifd = open_or_die(name, O_RDONLY); |
513 | /* fstat() is needed to get the file size. */ |
514 | if (fstat(ifd, &st) < 0) |
515 | err(1, "fstat() on initrd '%s'", name); |
516 | |
517 | /* |
518 | * We map the initrd at the top of memory, but mmap wants it to be |
519 | * page-aligned, so we round the size up for that. |
520 | */ |
521 | len = page_align(st.st_size); |
522 | map_at(ifd, from_guest_phys(mem - len), 0, st.st_size); |
523 | /* |
524 | * Once a file is mapped, you can close the file descriptor. It's a |
525 | * little odd, but quite useful. |
526 | */ |
527 | close(ifd); |
528 | verbose("mapped initrd %s size=%lu @ %p\n", name, len, (void*)mem-len); |
529 | |
530 | /* We return the initrd size. */ |
531 | return len; |
532 | } |
533 | /*:*/ |
534 | |
535 | /* |
536 | * Simple routine to roll all the commandline arguments together with spaces |
537 | * between them. |
538 | */ |
539 | static void concat(char *dst, char *args[]) |
540 | { |
541 | unsigned int i, len = 0; |
542 | |
543 | for (i = 0; args[i]; i++) { |
544 | if (i) { |
545 | strcat(dst+len, " "); |
546 | len++; |
547 | } |
548 | strcpy(dst+len, args[i]); |
549 | len += strlen(args[i]); |
550 | } |
551 | /* In case it's empty. */ |
552 | dst[len] = '\0'; |
553 | } |
554 | |
555 | /*L:185 |
556 | * This is where we actually tell the kernel to initialize the Guest. We |
557 | * saw the arguments it expects when we looked at initialize() in lguest_user.c: |
558 | * the base of Guest "physical" memory, the top physical page to allow and the |
559 | * entry point for the Guest. |
560 | */ |
561 | static void tell_kernel(unsigned long start) |
562 | { |
563 | unsigned long args[] = { LHREQ_INITIALIZE, |
564 | (unsigned long)guest_base, |
565 | guest_limit / getpagesize(), start }; |
566 | verbose("Guest: %p - %p (%#lx)\n", |
567 | guest_base, guest_base + guest_limit, guest_limit); |
568 | lguest_fd = open_or_die("/dev/lguest", O_RDWR); |
569 | if (write(lguest_fd, args, sizeof(args)) < 0) |
570 | err(1, "Writing to /dev/lguest"); |
571 | } |
572 | /*:*/ |
573 | |
574 | /*L:200 |
575 | * Device Handling. |
576 | * |
577 | * When the Guest gives us a buffer, it sends an array of addresses and sizes. |
578 | * We need to make sure it's not trying to reach into the Launcher itself, so |
579 | * we have a convenient routine which checks it and exits with an error message |
580 | * if something funny is going on: |
581 | */ |
582 | static void *_check_pointer(unsigned long addr, unsigned int size, |
583 | unsigned int line) |
584 | { |
585 | /* |
586 | * Check if the requested address and size exceeds the allocated memory, |
587 | * or addr + size wraps around. |
588 | */ |
589 | if ((addr + size) > guest_limit || (addr + size) < addr) |
590 | errx(1, "%s:%i: Invalid address %#lx", __FILE__, line, addr); |
591 | /* |
592 | * We return a pointer for the caller's convenience, now we know it's |
593 | * safe to use. |
594 | */ |
595 | return from_guest_phys(addr); |
596 | } |
597 | /* A macro which transparently hands the line number to the real function. */ |
598 | #define check_pointer(addr,size) _check_pointer(addr, size, __LINE__) |
599 | |
600 | /* |
601 | * Each buffer in the virtqueues is actually a chain of descriptors. This |
602 | * function returns the next descriptor in the chain, or vq->vring.num if we're |
603 | * at the end. |
604 | */ |
605 | static unsigned next_desc(struct vring_desc *desc, |
606 | unsigned int i, unsigned int max) |
607 | { |
608 | unsigned int next; |
609 | |
610 | /* If this descriptor says it doesn't chain, we're done. */ |
611 | if (!(desc[i].flags & VRING_DESC_F_NEXT)) |
612 | return max; |
613 | |
614 | /* Check they're not leading us off end of descriptors. */ |
615 | next = desc[i].next; |
616 | /* Make sure compiler knows to grab that: we don't want it changing! */ |
617 | wmb(); |
618 | |
619 | if (next >= max) |
620 | errx(1, "Desc next is %u", next); |
621 | |
622 | return next; |
623 | } |
624 | |
625 | /* |
626 | * This actually sends the interrupt for this virtqueue, if we've used a |
627 | * buffer. |
628 | */ |
629 | static void trigger_irq(struct virtqueue *vq) |
630 | { |
631 | unsigned long buf[] = { LHREQ_IRQ, vq->config.irq }; |
632 | |
633 | /* Don't inform them if nothing used. */ |
634 | if (!vq->pending_used) |
635 | return; |
636 | vq->pending_used = 0; |
637 | |
638 | /* If they don't want an interrupt, don't send one... */ |
639 | if (vq->vring.avail->flags & VRING_AVAIL_F_NO_INTERRUPT) { |
640 | /* ... unless they've asked us to force one on empty. */ |
641 | if (!vq->dev->irq_on_empty |
642 | || lg_last_avail(vq) != vq->vring.avail->idx) |
643 | return; |
644 | } |
645 | |
646 | /* Send the Guest an interrupt tell them we used something up. */ |
647 | if (write(lguest_fd, buf, sizeof(buf)) != 0) |
648 | err(1, "Triggering irq %i", vq->config.irq); |
649 | } |
650 | |
651 | /* |
652 | * This looks in the virtqueue for the first available buffer, and converts |
653 | * it to an iovec for convenient access. Since descriptors consist of some |
654 | * number of output then some number of input descriptors, it's actually two |
655 | * iovecs, but we pack them into one and note how many of each there were. |
656 | * |
657 | * This function waits if necessary, and returns the descriptor number found. |
658 | */ |
659 | static unsigned wait_for_vq_desc(struct virtqueue *vq, |
660 | struct iovec iov[], |
661 | unsigned int *out_num, unsigned int *in_num) |
662 | { |
663 | unsigned int i, head, max; |
664 | struct vring_desc *desc; |
665 | u16 last_avail = lg_last_avail(vq); |
666 | |
667 | /* There's nothing available? */ |
668 | while (last_avail == vq->vring.avail->idx) { |
669 | u64 event; |
670 | |
671 | /* |
672 | * Since we're about to sleep, now is a good time to tell the |
673 | * Guest about what we've used up to now. |
674 | */ |
675 | trigger_irq(vq); |
676 | |
677 | /* OK, now we need to know about added descriptors. */ |
678 | vq->vring.used->flags &= ~VRING_USED_F_NO_NOTIFY; |
679 | |
680 | /* |
681 | * They could have slipped one in as we were doing that: make |
682 | * sure it's written, then check again. |
683 | */ |
684 | mb(); |
685 | if (last_avail != vq->vring.avail->idx) { |
686 | vq->vring.used->flags |= VRING_USED_F_NO_NOTIFY; |
687 | break; |
688 | } |
689 | |
690 | /* Nothing new? Wait for eventfd to tell us they refilled. */ |
691 | if (read(vq->eventfd, &event, sizeof(event)) != sizeof(event)) |
692 | errx(1, "Event read failed?"); |
693 | |
694 | /* We don't need to be notified again. */ |
695 | vq->vring.used->flags |= VRING_USED_F_NO_NOTIFY; |
696 | } |
697 | |
698 | /* Check it isn't doing very strange things with descriptor numbers. */ |
699 | if ((u16)(vq->vring.avail->idx - last_avail) > vq->vring.num) |
700 | errx(1, "Guest moved used index from %u to %u", |
701 | last_avail, vq->vring.avail->idx); |
702 | |
703 | /* |
704 | * Grab the next descriptor number they're advertising, and increment |
705 | * the index we've seen. |
706 | */ |
707 | head = vq->vring.avail->ring[last_avail % vq->vring.num]; |
708 | lg_last_avail(vq)++; |
709 | |
710 | /* If their number is silly, that's a fatal mistake. */ |
711 | if (head >= vq->vring.num) |
712 | errx(1, "Guest says index %u is available", head); |
713 | |
714 | /* When we start there are none of either input nor output. */ |
715 | *out_num = *in_num = 0; |
716 | |
717 | max = vq->vring.num; |
718 | desc = vq->vring.desc; |
719 | i = head; |
720 | |
721 | /* |
722 | * If this is an indirect entry, then this buffer contains a descriptor |
723 | * table which we handle as if it's any normal descriptor chain. |
724 | */ |
725 | if (desc[i].flags & VRING_DESC_F_INDIRECT) { |
726 | if (desc[i].len % sizeof(struct vring_desc)) |
727 | errx(1, "Invalid size for indirect buffer table"); |
728 | |
729 | max = desc[i].len / sizeof(struct vring_desc); |
730 | desc = check_pointer(desc[i].addr, desc[i].len); |
731 | i = 0; |
732 | } |
733 | |
734 | do { |
735 | /* Grab the first descriptor, and check it's OK. */ |
736 | iov[*out_num + *in_num].iov_len = desc[i].len; |
737 | iov[*out_num + *in_num].iov_base |
738 | = check_pointer(desc[i].addr, desc[i].len); |
739 | /* If this is an input descriptor, increment that count. */ |
740 | if (desc[i].flags & VRING_DESC_F_WRITE) |
741 | (*in_num)++; |
742 | else { |
743 | /* |
744 | * If it's an output descriptor, they're all supposed |
745 | * to come before any input descriptors. |
746 | */ |
747 | if (*in_num) |
748 | errx(1, "Descriptor has out after in"); |
749 | (*out_num)++; |
750 | } |
751 | |
752 | /* If we've got too many, that implies a descriptor loop. */ |
753 | if (*out_num + *in_num > max) |
754 | errx(1, "Looped descriptor"); |
755 | } while ((i = next_desc(desc, i, max)) != max); |
756 | |
757 | return head; |
758 | } |
759 | |
760 | /* |
761 | * After we've used one of their buffers, we tell the Guest about it. Sometime |
762 | * later we'll want to send them an interrupt using trigger_irq(); note that |
763 | * wait_for_vq_desc() does that for us if it has to wait. |
764 | */ |
765 | static void add_used(struct virtqueue *vq, unsigned int head, int len) |
766 | { |
767 | struct vring_used_elem *used; |
768 | |
769 | /* |
770 | * The virtqueue contains a ring of used buffers. Get a pointer to the |
771 | * next entry in that used ring. |
772 | */ |
773 | used = &vq->vring.used->ring[vq->vring.used->idx % vq->vring.num]; |
774 | used->id = head; |
775 | used->len = len; |
776 | /* Make sure buffer is written before we update index. */ |
777 | wmb(); |
778 | vq->vring.used->idx++; |
779 | vq->pending_used++; |
780 | } |
781 | |
782 | /* And here's the combo meal deal. Supersize me! */ |
783 | static void add_used_and_trigger(struct virtqueue *vq, unsigned head, int len) |
784 | { |
785 | add_used(vq, head, len); |
786 | trigger_irq(vq); |
787 | } |
788 | |
789 | /* |
790 | * The Console |
791 | * |
792 | * We associate some data with the console for our exit hack. |
793 | */ |
794 | struct console_abort { |
795 | /* How many times have they hit ^C? */ |
796 | int count; |
797 | /* When did they start? */ |
798 | struct timeval start; |
799 | }; |
800 | |
801 | /* This is the routine which handles console input (ie. stdin). */ |
802 | static void console_input(struct virtqueue *vq) |
803 | { |
804 | int len; |
805 | unsigned int head, in_num, out_num; |
806 | struct console_abort *abort = vq->dev->priv; |
807 | struct iovec iov[vq->vring.num]; |
808 | |
809 | /* Make sure there's a descriptor available. */ |
810 | head = wait_for_vq_desc(vq, iov, &out_num, &in_num); |
811 | if (out_num) |
812 | errx(1, "Output buffers in console in queue?"); |
813 | |
814 | /* Read into it. This is where we usually wait. */ |
815 | len = readv(STDIN_FILENO, iov, in_num); |
816 | if (len <= 0) { |
817 | /* Ran out of input? */ |
818 | warnx("Failed to get console input, ignoring console."); |
819 | /* |
820 | * For simplicity, dying threads kill the whole Launcher. So |
821 | * just nap here. |
822 | */ |
823 | for (;;) |
824 | pause(); |
825 | } |
826 | |
827 | /* Tell the Guest we used a buffer. */ |
828 | add_used_and_trigger(vq, head, len); |
829 | |
830 | /* |
831 | * Three ^C within one second? Exit. |
832 | * |
833 | * This is such a hack, but works surprisingly well. Each ^C has to |
834 | * be in a buffer by itself, so they can't be too fast. But we check |
835 | * that we get three within about a second, so they can't be too |
836 | * slow. |
837 | */ |
838 | if (len != 1 || ((char *)iov[0].iov_base)[0] != 3) { |
839 | abort->count = 0; |
840 | return; |
841 | } |
842 | |
843 | abort->count++; |
844 | if (abort->count == 1) |
845 | gettimeofday(&abort->start, NULL); |
846 | else if (abort->count == 3) { |
847 | struct timeval now; |
848 | gettimeofday(&now, NULL); |
849 | /* Kill all Launcher processes with SIGINT, like normal ^C */ |
850 | if (now.tv_sec <= abort->start.tv_sec+1) |
851 | kill(0, SIGINT); |
852 | abort->count = 0; |
853 | } |
854 | } |
855 | |
856 | /* This is the routine which handles console output (ie. stdout). */ |
857 | static void console_output(struct virtqueue *vq) |
858 | { |
859 | unsigned int head, out, in; |
860 | struct iovec iov[vq->vring.num]; |
861 | |
862 | /* We usually wait in here, for the Guest to give us something. */ |
863 | head = wait_for_vq_desc(vq, iov, &out, &in); |
864 | if (in) |
865 | errx(1, "Input buffers in console output queue?"); |
866 | |
867 | /* writev can return a partial write, so we loop here. */ |
868 | while (!iov_empty(iov, out)) { |
869 | int len = writev(STDOUT_FILENO, iov, out); |
870 | if (len <= 0) |
871 | err(1, "Write to stdout gave %i", len); |
872 | iov_consume(iov, out, len); |
873 | } |
874 | |
875 | /* |
876 | * We're finished with that buffer: if we're going to sleep, |
877 | * wait_for_vq_desc() will prod the Guest with an interrupt. |
878 | */ |
879 | add_used(vq, head, 0); |
880 | } |
881 | |
882 | /* |
883 | * The Network |
884 | * |
885 | * Handling output for network is also simple: we get all the output buffers |
886 | * and write them to /dev/net/tun. |
887 | */ |
888 | struct net_info { |
889 | int tunfd; |
890 | }; |
891 | |
892 | static void net_output(struct virtqueue *vq) |
893 | { |
894 | struct net_info *net_info = vq->dev->priv; |
895 | unsigned int head, out, in; |
896 | struct iovec iov[vq->vring.num]; |
897 | |
898 | /* We usually wait in here for the Guest to give us a packet. */ |
899 | head = wait_for_vq_desc(vq, iov, &out, &in); |
900 | if (in) |
901 | errx(1, "Input buffers in net output queue?"); |
902 | /* |
903 | * Send the whole thing through to /dev/net/tun. It expects the exact |
904 | * same format: what a coincidence! |
905 | */ |
906 | if (writev(net_info->tunfd, iov, out) < 0) |
907 | errx(1, "Write to tun failed?"); |
908 | |
909 | /* |
910 | * Done with that one; wait_for_vq_desc() will send the interrupt if |
911 | * all packets are processed. |
912 | */ |
913 | add_used(vq, head, 0); |
914 | } |
915 | |
916 | /* |
917 | * Handling network input is a bit trickier, because I've tried to optimize it. |
918 | * |
919 | * First we have a helper routine which tells is if from this file descriptor |
920 | * (ie. the /dev/net/tun device) will block: |
921 | */ |
922 | static bool will_block(int fd) |
923 | { |
924 | fd_set fdset; |
925 | struct timeval zero = { 0, 0 }; |
926 | FD_ZERO(&fdset); |
927 | FD_SET(fd, &fdset); |
928 | return select(fd+1, &fdset, NULL, NULL, &zero) != 1; |
929 | } |
930 | |
931 | /* |
932 | * This handles packets coming in from the tun device to our Guest. Like all |
933 | * service routines, it gets called again as soon as it returns, so you don't |
934 | * see a while(1) loop here. |
935 | */ |
936 | static void net_input(struct virtqueue *vq) |
937 | { |
938 | int len; |
939 | unsigned int head, out, in; |
940 | struct iovec iov[vq->vring.num]; |
941 | struct net_info *net_info = vq->dev->priv; |
942 | |
943 | /* |
944 | * Get a descriptor to write an incoming packet into. This will also |
945 | * send an interrupt if they're out of descriptors. |
946 | */ |
947 | head = wait_for_vq_desc(vq, iov, &out, &in); |
948 | if (out) |
949 | errx(1, "Output buffers in net input queue?"); |
950 | |
951 | /* |
952 | * If it looks like we'll block reading from the tun device, send them |
953 | * an interrupt. |
954 | */ |
955 | if (vq->pending_used && will_block(net_info->tunfd)) |
956 | trigger_irq(vq); |
957 | |
958 | /* |
959 | * Read in the packet. This is where we normally wait (when there's no |
960 | * incoming network traffic). |
961 | */ |
962 | len = readv(net_info->tunfd, iov, in); |
963 | if (len <= 0) |
964 | err(1, "Failed to read from tun."); |
965 | |
966 | /* |
967 | * Mark that packet buffer as used, but don't interrupt here. We want |
968 | * to wait until we've done as much work as we can. |
969 | */ |
970 | add_used(vq, head, len); |
971 | } |
972 | /*:*/ |
973 | |
974 | /* This is the helper to create threads: run the service routine in a loop. */ |
975 | static int do_thread(void *_vq) |
976 | { |
977 | struct virtqueue *vq = _vq; |
978 | |
979 | for (;;) |
980 | vq->service(vq); |
981 | return 0; |
982 | } |
983 | |
984 | /* |
985 | * When a child dies, we kill our entire process group with SIGTERM. This |
986 | * also has the side effect that the shell restores the console for us! |
987 | */ |
988 | static void kill_launcher(int signal) |
989 | { |
990 | kill(0, SIGTERM); |
991 | } |
992 | |
993 | static void reset_device(struct device *dev) |
994 | { |
995 | struct virtqueue *vq; |
996 | |
997 | verbose("Resetting device %s\n", dev->name); |
998 | |
999 | /* Clear any features they've acked. */ |
1000 | memset(get_feature_bits(dev) + dev->feature_len, 0, dev->feature_len); |
1001 | |
1002 | /* We're going to be explicitly killing threads, so ignore them. */ |
1003 | signal(SIGCHLD, SIG_IGN); |
1004 | |
1005 | /* Zero out the virtqueues, get rid of their threads */ |
1006 | for (vq = dev->vq; vq; vq = vq->next) { |
1007 | if (vq->thread != (pid_t)-1) { |
1008 | kill(vq->thread, SIGTERM); |
1009 | waitpid(vq->thread, NULL, 0); |
1010 | vq->thread = (pid_t)-1; |
1011 | } |
1012 | memset(vq->vring.desc, 0, |
1013 | vring_size(vq->config.num, LGUEST_VRING_ALIGN)); |
1014 | lg_last_avail(vq) = 0; |
1015 | } |
1016 | dev->running = false; |
1017 | |
1018 | /* Now we care if threads die. */ |
1019 | signal(SIGCHLD, (void *)kill_launcher); |
1020 | } |
1021 | |
1022 | /*L:216 |
1023 | * This actually creates the thread which services the virtqueue for a device. |
1024 | */ |
1025 | static void create_thread(struct virtqueue *vq) |
1026 | { |
1027 | /* |
1028 | * Create stack for thread. Since the stack grows upwards, we point |
1029 | * the stack pointer to the end of this region. |
1030 | */ |
1031 | char *stack = malloc(32768); |
1032 | unsigned long args[] = { LHREQ_EVENTFD, |
1033 | vq->config.pfn*getpagesize(), 0 }; |
1034 | |
1035 | /* Create a zero-initialized eventfd. */ |
1036 | vq->eventfd = eventfd(0, 0); |
1037 | if (vq->eventfd < 0) |
1038 | err(1, "Creating eventfd"); |
1039 | args[2] = vq->eventfd; |
1040 | |
1041 | /* |
1042 | * Attach an eventfd to this virtqueue: it will go off when the Guest |
1043 | * does an LHCALL_NOTIFY for this vq. |
1044 | */ |
1045 | if (write(lguest_fd, &args, sizeof(args)) != 0) |
1046 | err(1, "Attaching eventfd"); |
1047 | |
1048 | /* |
1049 | * CLONE_VM: because it has to access the Guest memory, and SIGCHLD so |
1050 | * we get a signal if it dies. |
1051 | */ |
1052 | vq->thread = clone(do_thread, stack + 32768, CLONE_VM | SIGCHLD, vq); |
1053 | if (vq->thread == (pid_t)-1) |
1054 | err(1, "Creating clone"); |
1055 | |
1056 | /* We close our local copy now the child has it. */ |
1057 | close(vq->eventfd); |
1058 | } |
1059 | |
1060 | static bool accepted_feature(struct device *dev, unsigned int bit) |
1061 | { |
1062 | const u8 *features = get_feature_bits(dev) + dev->feature_len; |
1063 | |
1064 | if (dev->feature_len < bit / CHAR_BIT) |
1065 | return false; |
1066 | return features[bit / CHAR_BIT] & (1 << (bit % CHAR_BIT)); |
1067 | } |
1068 | |
1069 | static void start_device(struct device *dev) |
1070 | { |
1071 | unsigned int i; |
1072 | struct virtqueue *vq; |
1073 | |
1074 | verbose("Device %s OK: offered", dev->name); |
1075 | for (i = 0; i < dev->feature_len; i++) |
1076 | verbose(" %02x", get_feature_bits(dev)[i]); |
1077 | verbose(", accepted"); |
1078 | for (i = 0; i < dev->feature_len; i++) |
1079 | verbose(" %02x", get_feature_bits(dev) |
1080 | [dev->feature_len+i]); |
1081 | |
1082 | dev->irq_on_empty = accepted_feature(dev, VIRTIO_F_NOTIFY_ON_EMPTY); |
1083 | |
1084 | for (vq = dev->vq; vq; vq = vq->next) { |
1085 | if (vq->service) |
1086 | create_thread(vq); |
1087 | } |
1088 | dev->running = true; |
1089 | } |
1090 | |
1091 | static void cleanup_devices(void) |
1092 | { |
1093 | struct device *dev; |
1094 | |
1095 | for (dev = devices.dev; dev; dev = dev->next) |
1096 | reset_device(dev); |
1097 | |
1098 | /* If we saved off the original terminal settings, restore them now. */ |
1099 | if (orig_term.c_lflag & (ISIG|ICANON|ECHO)) |
1100 | tcsetattr(STDIN_FILENO, TCSANOW, &orig_term); |
1101 | } |
1102 | |
1103 | /* When the Guest tells us they updated the status field, we handle it. */ |
1104 | static void update_device_status(struct device *dev) |
1105 | { |
1106 | /* A zero status is a reset, otherwise it's a set of flags. */ |
1107 | if (dev->desc->status == 0) |
1108 | reset_device(dev); |
1109 | else if (dev->desc->status & VIRTIO_CONFIG_S_FAILED) { |
1110 | warnx("Device %s configuration FAILED", dev->name); |
1111 | if (dev->running) |
1112 | reset_device(dev); |
1113 | } else if (dev->desc->status & VIRTIO_CONFIG_S_DRIVER_OK) { |
1114 | if (!dev->running) |
1115 | start_device(dev); |
1116 | } |
1117 | } |
1118 | |
1119 | /*L:215 |
1120 | * This is the generic routine we call when the Guest uses LHCALL_NOTIFY. In |
1121 | * particular, it's used to notify us of device status changes during boot. |
1122 | */ |
1123 | static void handle_output(unsigned long addr) |
1124 | { |
1125 | struct device *i; |
1126 | |
1127 | /* Check each device. */ |
1128 | for (i = devices.dev; i; i = i->next) { |
1129 | struct virtqueue *vq; |
1130 | |
1131 | /* |
1132 | * Notifications to device descriptors mean they updated the |
1133 | * device status. |
1134 | */ |
1135 | if (from_guest_phys(addr) == i->desc) { |
1136 | update_device_status(i); |
1137 | return; |
1138 | } |
1139 | |
1140 | /* |
1141 | * Devices *can* be used before status is set to DRIVER_OK. |
1142 | * The original plan was that they would never do this: they |
1143 | * would always finish setting up their status bits before |
1144 | * actually touching the virtqueues. In practice, we allowed |
1145 | * them to, and they do (eg. the disk probes for partition |
1146 | * tables as part of initialization). |
1147 | * |
1148 | * If we see this, we start the device: once it's running, we |
1149 | * expect the device to catch all the notifications. |
1150 | */ |
1151 | for (vq = i->vq; vq; vq = vq->next) { |
1152 | if (addr != vq->config.pfn*getpagesize()) |
1153 | continue; |
1154 | if (i->running) |
1155 | errx(1, "Notification on running %s", i->name); |
1156 | /* This just calls create_thread() for each virtqueue */ |
1157 | start_device(i); |
1158 | return; |
1159 | } |
1160 | } |
1161 | |
1162 | /* |
1163 | * Early console write is done using notify on a nul-terminated string |
1164 | * in Guest memory. It's also great for hacking debugging messages |
1165 | * into a Guest. |
1166 | */ |
1167 | if (addr >= guest_limit) |
1168 | errx(1, "Bad NOTIFY %#lx", addr); |
1169 | |
1170 | write(STDOUT_FILENO, from_guest_phys(addr), |
1171 | strnlen(from_guest_phys(addr), guest_limit - addr)); |
1172 | } |
1173 | |
1174 | /*L:190 |
1175 | * Device Setup |
1176 | * |
1177 | * All devices need a descriptor so the Guest knows it exists, and a "struct |
1178 | * device" so the Launcher can keep track of it. We have common helper |
1179 | * routines to allocate and manage them. |
1180 | */ |
1181 | |
1182 | /* |
1183 | * The layout of the device page is a "struct lguest_device_desc" followed by a |
1184 | * number of virtqueue descriptors, then two sets of feature bits, then an |
1185 | * array of configuration bytes. This routine returns the configuration |
1186 | * pointer. |
1187 | */ |
1188 | static u8 *device_config(const struct device *dev) |
1189 | { |
1190 | return (void *)(dev->desc + 1) |
1191 | + dev->num_vq * sizeof(struct lguest_vqconfig) |
1192 | + dev->feature_len * 2; |
1193 | } |
1194 | |
1195 | /* |
1196 | * This routine allocates a new "struct lguest_device_desc" from descriptor |
1197 | * table page just above the Guest's normal memory. It returns a pointer to |
1198 | * that descriptor. |
1199 | */ |
1200 | static struct lguest_device_desc *new_dev_desc(u16 type) |
1201 | { |
1202 | struct lguest_device_desc d = { .type = type }; |
1203 | void *p; |
1204 | |
1205 | /* Figure out where the next device config is, based on the last one. */ |
1206 | if (devices.lastdev) |
1207 | p = device_config(devices.lastdev) |
1208 | + devices.lastdev->desc->config_len; |
1209 | else |
1210 | p = devices.descpage; |
1211 | |
1212 | /* We only have one page for all the descriptors. */ |
1213 | if (p + sizeof(d) > (void *)devices.descpage + getpagesize()) |
1214 | errx(1, "Too many devices"); |
1215 | |
1216 | /* p might not be aligned, so we memcpy in. */ |
1217 | return memcpy(p, &d, sizeof(d)); |
1218 | } |
1219 | |
1220 | /* |
1221 | * Each device descriptor is followed by the description of its virtqueues. We |
1222 | * specify how many descriptors the virtqueue is to have. |
1223 | */ |
1224 | static void add_virtqueue(struct device *dev, unsigned int num_descs, |
1225 | void (*service)(struct virtqueue *)) |
1226 | { |
1227 | unsigned int pages; |
1228 | struct virtqueue **i, *vq = malloc(sizeof(*vq)); |
1229 | void *p; |
1230 | |
1231 | /* First we need some memory for this virtqueue. */ |
1232 | pages = (vring_size(num_descs, LGUEST_VRING_ALIGN) + getpagesize() - 1) |
1233 | / getpagesize(); |
1234 | p = get_pages(pages); |
1235 | |
1236 | /* Initialize the virtqueue */ |
1237 | vq->next = NULL; |
1238 | vq->last_avail_idx = 0; |
1239 | vq->dev = dev; |
1240 | |
1241 | /* |
1242 | * This is the routine the service thread will run, and its Process ID |
1243 | * once it's running. |
1244 | */ |
1245 | vq->service = service; |
1246 | vq->thread = (pid_t)-1; |
1247 | |
1248 | /* Initialize the configuration. */ |
1249 | vq->config.num = num_descs; |
1250 | vq->config.irq = devices.next_irq++; |
1251 | vq->config.pfn = to_guest_phys(p) / getpagesize(); |
1252 | |
1253 | /* Initialize the vring. */ |
1254 | vring_init(&vq->vring, num_descs, p, LGUEST_VRING_ALIGN); |
1255 | |
1256 | /* |
1257 | * Append virtqueue to this device's descriptor. We use |
1258 | * device_config() to get the end of the device's current virtqueues; |
1259 | * we check that we haven't added any config or feature information |
1260 | * yet, otherwise we'd be overwriting them. |
1261 | */ |
1262 | assert(dev->desc->config_len == 0 && dev->desc->feature_len == 0); |
1263 | memcpy(device_config(dev), &vq->config, sizeof(vq->config)); |
1264 | dev->num_vq++; |
1265 | dev->desc->num_vq++; |
1266 | |
1267 | verbose("Virtqueue page %#lx\n", to_guest_phys(p)); |
1268 | |
1269 | /* |
1270 | * Add to tail of list, so dev->vq is first vq, dev->vq->next is |
1271 | * second. |
1272 | */ |
1273 | for (i = &dev->vq; *i; i = &(*i)->next); |
1274 | *i = vq; |
1275 | } |
1276 | |
1277 | /* |
1278 | * The first half of the feature bitmask is for us to advertise features. The |
1279 | * second half is for the Guest to accept features. |
1280 | */ |
1281 | static void add_feature(struct device *dev, unsigned bit) |
1282 | { |
1283 | u8 *features = get_feature_bits(dev); |
1284 | |
1285 | /* We can't extend the feature bits once we've added config bytes */ |
1286 | if (dev->desc->feature_len <= bit / CHAR_BIT) { |
1287 | assert(dev->desc->config_len == 0); |
1288 | dev->feature_len = dev->desc->feature_len = (bit/CHAR_BIT) + 1; |
1289 | } |
1290 | |
1291 | features[bit / CHAR_BIT] |= (1 << (bit % CHAR_BIT)); |
1292 | } |
1293 | |
1294 | /* |
1295 | * This routine sets the configuration fields for an existing device's |
1296 | * descriptor. It only works for the last device, but that's OK because that's |
1297 | * how we use it. |
1298 | */ |
1299 | static void set_config(struct device *dev, unsigned len, const void *conf) |
1300 | { |
1301 | /* Check we haven't overflowed our single page. */ |
1302 | if (device_config(dev) + len > devices.descpage + getpagesize()) |
1303 | errx(1, "Too many devices"); |
1304 | |
1305 | /* Copy in the config information, and store the length. */ |
1306 | memcpy(device_config(dev), conf, len); |
1307 | dev->desc->config_len = len; |
1308 | |
1309 | /* Size must fit in config_len field (8 bits)! */ |
1310 | assert(dev->desc->config_len == len); |
1311 | } |
1312 | |
1313 | /* |
1314 | * This routine does all the creation and setup of a new device, including |
1315 | * calling new_dev_desc() to allocate the descriptor and device memory. We |
1316 | * don't actually start the service threads until later. |
1317 | * |
1318 | * See what I mean about userspace being boring? |
1319 | */ |
1320 | static struct device *new_device(const char *name, u16 type) |
1321 | { |
1322 | struct device *dev = malloc(sizeof(*dev)); |
1323 | |
1324 | /* Now we populate the fields one at a time. */ |
1325 | dev->desc = new_dev_desc(type); |
1326 | dev->name = name; |
1327 | dev->vq = NULL; |
1328 | dev->feature_len = 0; |
1329 | dev->num_vq = 0; |
1330 | dev->running = false; |
1331 | |
1332 | /* |
1333 | * Append to device list. Prepending to a single-linked list is |
1334 | * easier, but the user expects the devices to be arranged on the bus |
1335 | * in command-line order. The first network device on the command line |
1336 | * is eth0, the first block device /dev/vda, etc. |
1337 | */ |
1338 | if (devices.lastdev) |
1339 | devices.lastdev->next = dev; |
1340 | else |
1341 | devices.dev = dev; |
1342 | devices.lastdev = dev; |
1343 | |
1344 | return dev; |
1345 | } |
1346 | |
1347 | /* |
1348 | * Our first setup routine is the console. It's a fairly simple device, but |
1349 | * UNIX tty handling makes it uglier than it could be. |
1350 | */ |
1351 | static void setup_console(void) |
1352 | { |
1353 | struct device *dev; |
1354 | |
1355 | /* If we can save the initial standard input settings... */ |
1356 | if (tcgetattr(STDIN_FILENO, &orig_term) == 0) { |
1357 | struct termios term = orig_term; |
1358 | /* |
1359 | * Then we turn off echo, line buffering and ^C etc: We want a |
1360 | * raw input stream to the Guest. |
1361 | */ |
1362 | term.c_lflag &= ~(ISIG|ICANON|ECHO); |
1363 | tcsetattr(STDIN_FILENO, TCSANOW, &term); |
1364 | } |
1365 | |
1366 | dev = new_device("console", VIRTIO_ID_CONSOLE); |
1367 | |
1368 | /* We store the console state in dev->priv, and initialize it. */ |
1369 | dev->priv = malloc(sizeof(struct console_abort)); |
1370 | ((struct console_abort *)dev->priv)->count = 0; |
1371 | |
1372 | /* |
1373 | * The console needs two virtqueues: the input then the output. When |
1374 | * they put something the input queue, we make sure we're listening to |
1375 | * stdin. When they put something in the output queue, we write it to |
1376 | * stdout. |
1377 | */ |
1378 | add_virtqueue(dev, VIRTQUEUE_NUM, console_input); |
1379 | add_virtqueue(dev, VIRTQUEUE_NUM, console_output); |
1380 | |
1381 | verbose("device %u: console\n", ++devices.device_num); |
1382 | } |
1383 | /*:*/ |
1384 | |
1385 | /*M:010 |
1386 | * Inter-guest networking is an interesting area. Simplest is to have a |
1387 | * --sharenet=<name> option which opens or creates a named pipe. This can be |
1388 | * used to send packets to another guest in a 1:1 manner. |
1389 | * |
1390 | * More sopisticated is to use one of the tools developed for project like UML |
1391 | * to do networking. |
1392 | * |
1393 | * Faster is to do virtio bonding in kernel. Doing this 1:1 would be |
1394 | * completely generic ("here's my vring, attach to your vring") and would work |
1395 | * for any traffic. Of course, namespace and permissions issues need to be |
1396 | * dealt with. A more sophisticated "multi-channel" virtio_net.c could hide |
1397 | * multiple inter-guest channels behind one interface, although it would |
1398 | * require some manner of hotplugging new virtio channels. |
1399 | * |
1400 | * Finally, we could implement a virtio network switch in the kernel. |
1401 | :*/ |
1402 | |
1403 | static u32 str2ip(const char *ipaddr) |
1404 | { |
1405 | unsigned int b[4]; |
1406 | |
1407 | if (sscanf(ipaddr, "%u.%u.%u.%u", &b[0], &b[1], &b[2], &b[3]) != 4) |
1408 | errx(1, "Failed to parse IP address '%s'", ipaddr); |
1409 | return (b[0] << 24) | (b[1] << 16) | (b[2] << 8) | b[3]; |
1410 | } |
1411 | |
1412 | static void str2mac(const char *macaddr, unsigned char mac[6]) |
1413 | { |
1414 | unsigned int m[6]; |
1415 | if (sscanf(macaddr, "%02x:%02x:%02x:%02x:%02x:%02x", |
1416 | &m[0], &m[1], &m[2], &m[3], &m[4], &m[5]) != 6) |
1417 | errx(1, "Failed to parse mac address '%s'", macaddr); |
1418 | mac[0] = m[0]; |
1419 | mac[1] = m[1]; |
1420 | mac[2] = m[2]; |
1421 | mac[3] = m[3]; |
1422 | mac[4] = m[4]; |
1423 | mac[5] = m[5]; |
1424 | } |
1425 | |
1426 | /* |
1427 | * This code is "adapted" from libbridge: it attaches the Host end of the |
1428 | * network device to the bridge device specified by the command line. |
1429 | * |
1430 | * This is yet another James Morris contribution (I'm an IP-level guy, so I |
1431 | * dislike bridging), and I just try not to break it. |
1432 | */ |
1433 | static void add_to_bridge(int fd, const char *if_name, const char *br_name) |
1434 | { |
1435 | int ifidx; |
1436 | struct ifreq ifr; |
1437 | |
1438 | if (!*br_name) |
1439 | errx(1, "must specify bridge name"); |
1440 | |
1441 | ifidx = if_nametoindex(if_name); |
1442 | if (!ifidx) |
1443 | errx(1, "interface %s does not exist!", if_name); |
1444 | |
1445 | strncpy(ifr.ifr_name, br_name, IFNAMSIZ); |
1446 | ifr.ifr_name[IFNAMSIZ-1] = '\0'; |
1447 | ifr.ifr_ifindex = ifidx; |
1448 | if (ioctl(fd, SIOCBRADDIF, &ifr) < 0) |
1449 | err(1, "can't add %s to bridge %s", if_name, br_name); |
1450 | } |
1451 | |
1452 | /* |
1453 | * This sets up the Host end of the network device with an IP address, brings |
1454 | * it up so packets will flow, the copies the MAC address into the hwaddr |
1455 | * pointer. |
1456 | */ |
1457 | static void configure_device(int fd, const char *tapif, u32 ipaddr) |
1458 | { |
1459 | struct ifreq ifr; |
1460 | struct sockaddr_in sin; |
1461 | |
1462 | memset(&ifr, 0, sizeof(ifr)); |
1463 | strcpy(ifr.ifr_name, tapif); |
1464 | |
1465 | /* Don't read these incantations. Just cut & paste them like I did! */ |
1466 | sin.sin_family = AF_INET; |
1467 | sin.sin_addr.s_addr = htonl(ipaddr); |
1468 | memcpy(&ifr.ifr_addr, &sin, sizeof(sin)); |
1469 | if (ioctl(fd, SIOCSIFADDR, &ifr) != 0) |
1470 | err(1, "Setting %s interface address", tapif); |
1471 | ifr.ifr_flags = IFF_UP; |
1472 | if (ioctl(fd, SIOCSIFFLAGS, &ifr) != 0) |
1473 | err(1, "Bringing interface %s up", tapif); |
1474 | } |
1475 | |
1476 | static int get_tun_device(char tapif[IFNAMSIZ]) |
1477 | { |
1478 | struct ifreq ifr; |
1479 | int netfd; |
1480 | |
1481 | /* Start with this zeroed. Messy but sure. */ |
1482 | memset(&ifr, 0, sizeof(ifr)); |
1483 | |
1484 | /* |
1485 | * We open the /dev/net/tun device and tell it we want a tap device. A |
1486 | * tap device is like a tun device, only somehow different. To tell |
1487 | * the truth, I completely blundered my way through this code, but it |
1488 | * works now! |
1489 | */ |
1490 | netfd = open_or_die("/dev/net/tun", O_RDWR); |
1491 | ifr.ifr_flags = IFF_TAP | IFF_NO_PI | IFF_VNET_HDR; |
1492 | strcpy(ifr.ifr_name, "tap%d"); |
1493 | if (ioctl(netfd, TUNSETIFF, &ifr) != 0) |
1494 | err(1, "configuring /dev/net/tun"); |
1495 | |
1496 | if (ioctl(netfd, TUNSETOFFLOAD, |
1497 | TUN_F_CSUM|TUN_F_TSO4|TUN_F_TSO6|TUN_F_TSO_ECN) != 0) |
1498 | err(1, "Could not set features for tun device"); |
1499 | |
1500 | /* |
1501 | * We don't need checksums calculated for packets coming in this |
1502 | * device: trust us! |
1503 | */ |
1504 | ioctl(netfd, TUNSETNOCSUM, 1); |
1505 | |
1506 | memcpy(tapif, ifr.ifr_name, IFNAMSIZ); |
1507 | return netfd; |
1508 | } |
1509 | |
1510 | /*L:195 |
1511 | * Our network is a Host<->Guest network. This can either use bridging or |
1512 | * routing, but the principle is the same: it uses the "tun" device to inject |
1513 | * packets into the Host as if they came in from a normal network card. We |
1514 | * just shunt packets between the Guest and the tun device. |
1515 | */ |
1516 | static void setup_tun_net(char *arg) |
1517 | { |
1518 | struct device *dev; |
1519 | struct net_info *net_info = malloc(sizeof(*net_info)); |
1520 | int ipfd; |
1521 | u32 ip = INADDR_ANY; |
1522 | bool bridging = false; |
1523 | char tapif[IFNAMSIZ], *p; |
1524 | struct virtio_net_config conf; |
1525 | |
1526 | net_info->tunfd = get_tun_device(tapif); |
1527 | |
1528 | /* First we create a new network device. */ |
1529 | dev = new_device("net", VIRTIO_ID_NET); |
1530 | dev->priv = net_info; |
1531 | |
1532 | /* Network devices need a recv and a send queue, just like console. */ |
1533 | add_virtqueue(dev, VIRTQUEUE_NUM, net_input); |
1534 | add_virtqueue(dev, VIRTQUEUE_NUM, net_output); |
1535 | |
1536 | /* |
1537 | * We need a socket to perform the magic network ioctls to bring up the |
1538 | * tap interface, connect to the bridge etc. Any socket will do! |
1539 | */ |
1540 | ipfd = socket(PF_INET, SOCK_DGRAM, IPPROTO_IP); |
1541 | if (ipfd < 0) |
1542 | err(1, "opening IP socket"); |
1543 | |
1544 | /* If the command line was --tunnet=bridge:<name> do bridging. */ |
1545 | if (!strncmp(BRIDGE_PFX, arg, strlen(BRIDGE_PFX))) { |
1546 | arg += strlen(BRIDGE_PFX); |
1547 | bridging = true; |
1548 | } |
1549 | |
1550 | /* A mac address may follow the bridge name or IP address */ |
1551 | p = strchr(arg, ':'); |
1552 | if (p) { |
1553 | str2mac(p+1, conf.mac); |
1554 | add_feature(dev, VIRTIO_NET_F_MAC); |
1555 | *p = '\0'; |
1556 | } |
1557 | |
1558 | /* arg is now either an IP address or a bridge name */ |
1559 | if (bridging) |
1560 | add_to_bridge(ipfd, tapif, arg); |
1561 | else |
1562 | ip = str2ip(arg); |
1563 | |
1564 | /* Set up the tun device. */ |
1565 | configure_device(ipfd, tapif, ip); |
1566 | |
1567 | add_feature(dev, VIRTIO_F_NOTIFY_ON_EMPTY); |
1568 | /* Expect Guest to handle everything except UFO */ |
1569 | add_feature(dev, VIRTIO_NET_F_CSUM); |
1570 | add_feature(dev, VIRTIO_NET_F_GUEST_CSUM); |
1571 | add_feature(dev, VIRTIO_NET_F_GUEST_TSO4); |
1572 | add_feature(dev, VIRTIO_NET_F_GUEST_TSO6); |
1573 | add_feature(dev, VIRTIO_NET_F_GUEST_ECN); |
1574 | add_feature(dev, VIRTIO_NET_F_HOST_TSO4); |
1575 | add_feature(dev, VIRTIO_NET_F_HOST_TSO6); |
1576 | add_feature(dev, VIRTIO_NET_F_HOST_ECN); |
1577 | /* We handle indirect ring entries */ |
1578 | add_feature(dev, VIRTIO_RING_F_INDIRECT_DESC); |
1579 | set_config(dev, sizeof(conf), &conf); |
1580 | |
1581 | /* We don't need the socket any more; setup is done. */ |
1582 | close(ipfd); |
1583 | |
1584 | devices.device_num++; |
1585 | |
1586 | if (bridging) |
1587 | verbose("device %u: tun %s attached to bridge: %s\n", |
1588 | devices.device_num, tapif, arg); |
1589 | else |
1590 | verbose("device %u: tun %s: %s\n", |
1591 | devices.device_num, tapif, arg); |
1592 | } |
1593 | /*:*/ |
1594 | |
1595 | /* This hangs off device->priv. */ |
1596 | struct vblk_info { |
1597 | /* The size of the file. */ |
1598 | off64_t len; |
1599 | |
1600 | /* The file descriptor for the file. */ |
1601 | int fd; |
1602 | |
1603 | }; |
1604 | |
1605 | /*L:210 |
1606 | * The Disk |
1607 | * |
1608 | * The disk only has one virtqueue, so it only has one thread. It is really |
1609 | * simple: the Guest asks for a block number and we read or write that position |
1610 | * in the file. |
1611 | * |
1612 | * Before we serviced each virtqueue in a separate thread, that was unacceptably |
1613 | * slow: the Guest waits until the read is finished before running anything |
1614 | * else, even if it could have been doing useful work. |
1615 | * |
1616 | * We could have used async I/O, except it's reputed to suck so hard that |
1617 | * characters actually go missing from your code when you try to use it. |
1618 | */ |
1619 | static void blk_request(struct virtqueue *vq) |
1620 | { |
1621 | struct vblk_info *vblk = vq->dev->priv; |
1622 | unsigned int head, out_num, in_num, wlen; |
1623 | int ret; |
1624 | u8 *in; |
1625 | struct virtio_blk_outhdr *out; |
1626 | struct iovec iov[vq->vring.num]; |
1627 | off64_t off; |
1628 | |
1629 | /* |
1630 | * Get the next request, where we normally wait. It triggers the |
1631 | * interrupt to acknowledge previously serviced requests (if any). |
1632 | */ |
1633 | head = wait_for_vq_desc(vq, iov, &out_num, &in_num); |
1634 | |
1635 | /* |
1636 | * Every block request should contain at least one output buffer |
1637 | * (detailing the location on disk and the type of request) and one |
1638 | * input buffer (to hold the result). |
1639 | */ |
1640 | if (out_num == 0 || in_num == 0) |
1641 | errx(1, "Bad virtblk cmd %u out=%u in=%u", |
1642 | head, out_num, in_num); |
1643 | |
1644 | out = convert(&iov[0], struct virtio_blk_outhdr); |
1645 | in = convert(&iov[out_num+in_num-1], u8); |
1646 | /* |
1647 | * For historical reasons, block operations are expressed in 512 byte |
1648 | * "sectors". |
1649 | */ |
1650 | off = out->sector * 512; |
1651 | |
1652 | /* |
1653 | * In general the virtio block driver is allowed to try SCSI commands. |
1654 | * It'd be nice if we supported eject, for example, but we don't. |
1655 | */ |
1656 | if (out->type & VIRTIO_BLK_T_SCSI_CMD) { |
1657 | fprintf(stderr, "Scsi commands unsupported\n"); |
1658 | *in = VIRTIO_BLK_S_UNSUPP; |
1659 | wlen = sizeof(*in); |
1660 | } else if (out->type & VIRTIO_BLK_T_OUT) { |
1661 | /* |
1662 | * Write |
1663 | * |
1664 | * Move to the right location in the block file. This can fail |
1665 | * if they try to write past end. |
1666 | */ |
1667 | if (lseek64(vblk->fd, off, SEEK_SET) != off) |
1668 | err(1, "Bad seek to sector %llu", out->sector); |
1669 | |
1670 | ret = writev(vblk->fd, iov+1, out_num-1); |
1671 | verbose("WRITE to sector %llu: %i\n", out->sector, ret); |
1672 | |
1673 | /* |
1674 | * Grr... Now we know how long the descriptor they sent was, we |
1675 | * make sure they didn't try to write over the end of the block |
1676 | * file (possibly extending it). |
1677 | */ |
1678 | if (ret > 0 && off + ret > vblk->len) { |
1679 | /* Trim it back to the correct length */ |
1680 | ftruncate64(vblk->fd, vblk->len); |
1681 | /* Die, bad Guest, die. */ |
1682 | errx(1, "Write past end %llu+%u", off, ret); |
1683 | } |
1684 | |
1685 | wlen = sizeof(*in); |
1686 | *in = (ret >= 0 ? VIRTIO_BLK_S_OK : VIRTIO_BLK_S_IOERR); |
1687 | } else if (out->type & VIRTIO_BLK_T_FLUSH) { |
1688 | /* Flush */ |
1689 | ret = fdatasync(vblk->fd); |
1690 | verbose("FLUSH fdatasync: %i\n", ret); |
1691 | wlen = sizeof(*in); |
1692 | *in = (ret >= 0 ? VIRTIO_BLK_S_OK : VIRTIO_BLK_S_IOERR); |
1693 | } else { |
1694 | /* |
1695 | * Read |
1696 | * |
1697 | * Move to the right location in the block file. This can fail |
1698 | * if they try to read past end. |
1699 | */ |
1700 | if (lseek64(vblk->fd, off, SEEK_SET) != off) |
1701 | err(1, "Bad seek to sector %llu", out->sector); |
1702 | |
1703 | ret = readv(vblk->fd, iov+1, in_num-1); |
1704 | verbose("READ from sector %llu: %i\n", out->sector, ret); |
1705 | if (ret >= 0) { |
1706 | wlen = sizeof(*in) + ret; |
1707 | *in = VIRTIO_BLK_S_OK; |
1708 | } else { |
1709 | wlen = sizeof(*in); |
1710 | *in = VIRTIO_BLK_S_IOERR; |
1711 | } |
1712 | } |
1713 | |
1714 | /* Finished that request. */ |
1715 | add_used(vq, head, wlen); |
1716 | } |
1717 | |
1718 | /*L:198 This actually sets up a virtual block device. */ |
1719 | static void setup_block_file(const char *filename) |
1720 | { |
1721 | struct device *dev; |
1722 | struct vblk_info *vblk; |
1723 | struct virtio_blk_config conf; |
1724 | |
1725 | /* Creat the device. */ |
1726 | dev = new_device("block", VIRTIO_ID_BLOCK); |
1727 | |
1728 | /* The device has one virtqueue, where the Guest places requests. */ |
1729 | add_virtqueue(dev, VIRTQUEUE_NUM, blk_request); |
1730 | |
1731 | /* Allocate the room for our own bookkeeping */ |
1732 | vblk = dev->priv = malloc(sizeof(*vblk)); |
1733 | |
1734 | /* First we open the file and store the length. */ |
1735 | vblk->fd = open_or_die(filename, O_RDWR|O_LARGEFILE); |
1736 | vblk->len = lseek64(vblk->fd, 0, SEEK_END); |
1737 | |
1738 | /* We support FLUSH. */ |
1739 | add_feature(dev, VIRTIO_BLK_F_FLUSH); |
1740 | |
1741 | /* Tell Guest how many sectors this device has. */ |
1742 | conf.capacity = cpu_to_le64(vblk->len / 512); |
1743 | |
1744 | /* |
1745 | * Tell Guest not to put in too many descriptors at once: two are used |
1746 | * for the in and out elements. |
1747 | */ |
1748 | add_feature(dev, VIRTIO_BLK_F_SEG_MAX); |
1749 | conf.seg_max = cpu_to_le32(VIRTQUEUE_NUM - 2); |
1750 | |
1751 | /* Don't try to put whole struct: we have 8 bit limit. */ |
1752 | set_config(dev, offsetof(struct virtio_blk_config, geometry), &conf); |
1753 | |
1754 | verbose("device %u: virtblock %llu sectors\n", |
1755 | ++devices.device_num, le64_to_cpu(conf.capacity)); |
1756 | } |
1757 | |
1758 | /*L:211 |
1759 | * Our random number generator device reads from /dev/random into the Guest's |
1760 | * input buffers. The usual case is that the Guest doesn't want random numbers |
1761 | * and so has no buffers although /dev/random is still readable, whereas |
1762 | * console is the reverse. |
1763 | * |
1764 | * The same logic applies, however. |
1765 | */ |
1766 | struct rng_info { |
1767 | int rfd; |
1768 | }; |
1769 | |
1770 | static void rng_input(struct virtqueue *vq) |
1771 | { |
1772 | int len; |
1773 | unsigned int head, in_num, out_num, totlen = 0; |
1774 | struct rng_info *rng_info = vq->dev->priv; |
1775 | struct iovec iov[vq->vring.num]; |
1776 | |
1777 | /* First we need a buffer from the Guests's virtqueue. */ |
1778 | head = wait_for_vq_desc(vq, iov, &out_num, &in_num); |
1779 | if (out_num) |
1780 | errx(1, "Output buffers in rng?"); |
1781 | |
1782 | /* |
1783 | * Just like the console write, we loop to cover the whole iovec. |
1784 | * In this case, short reads actually happen quite a bit. |
1785 | */ |
1786 | while (!iov_empty(iov, in_num)) { |
1787 | len = readv(rng_info->rfd, iov, in_num); |
1788 | if (len <= 0) |
1789 | err(1, "Read from /dev/random gave %i", len); |
1790 | iov_consume(iov, in_num, len); |
1791 | totlen += len; |
1792 | } |
1793 | |
1794 | /* Tell the Guest about the new input. */ |
1795 | add_used(vq, head, totlen); |
1796 | } |
1797 | |
1798 | /*L:199 |
1799 | * This creates a "hardware" random number device for the Guest. |
1800 | */ |
1801 | static void setup_rng(void) |
1802 | { |
1803 | struct device *dev; |
1804 | struct rng_info *rng_info = malloc(sizeof(*rng_info)); |
1805 | |
1806 | /* Our device's privat info simply contains the /dev/random fd. */ |
1807 | rng_info->rfd = open_or_die("/dev/random", O_RDONLY); |
1808 | |
1809 | /* Create the new device. */ |
1810 | dev = new_device("rng", VIRTIO_ID_RNG); |
1811 | dev->priv = rng_info; |
1812 | |
1813 | /* The device has one virtqueue, where the Guest places inbufs. */ |
1814 | add_virtqueue(dev, VIRTQUEUE_NUM, rng_input); |
1815 | |
1816 | verbose("device %u: rng\n", devices.device_num++); |
1817 | } |
1818 | /* That's the end of device setup. */ |
1819 | |
1820 | /*L:230 Reboot is pretty easy: clean up and exec() the Launcher afresh. */ |
1821 | static void __attribute__((noreturn)) restart_guest(void) |
1822 | { |
1823 | unsigned int i; |
1824 | |
1825 | /* |
1826 | * Since we don't track all open fds, we simply close everything beyond |
1827 | * stderr. |
1828 | */ |
1829 | for (i = 3; i < FD_SETSIZE; i++) |
1830 | close(i); |
1831 | |
1832 | /* Reset all the devices (kills all threads). */ |
1833 | cleanup_devices(); |
1834 | |
1835 | execv(main_args[0], main_args); |
1836 | err(1, "Could not exec %s", main_args[0]); |
1837 | } |
1838 | |
1839 | /*L:220 |
1840 | * Finally we reach the core of the Launcher which runs the Guest, serves |
1841 | * its input and output, and finally, lays it to rest. |
1842 | */ |
1843 | static void __attribute__((noreturn)) run_guest(void) |
1844 | { |
1845 | for (;;) { |
1846 | unsigned long notify_addr; |
1847 | int readval; |
1848 | |
1849 | /* We read from the /dev/lguest device to run the Guest. */ |
1850 | readval = pread(lguest_fd, ¬ify_addr, |
1851 | sizeof(notify_addr), cpu_id); |
1852 | |
1853 | /* One unsigned long means the Guest did HCALL_NOTIFY */ |
1854 | if (readval == sizeof(notify_addr)) { |
1855 | verbose("Notify on address %#lx\n", notify_addr); |
1856 | handle_output(notify_addr); |
1857 | /* ENOENT means the Guest died. Reading tells us why. */ |
1858 | } else if (errno == ENOENT) { |
1859 | char reason[1024] = { 0 }; |
1860 | pread(lguest_fd, reason, sizeof(reason)-1, cpu_id); |
1861 | errx(1, "%s", reason); |
1862 | /* ERESTART means that we need to reboot the guest */ |
1863 | } else if (errno == ERESTART) { |
1864 | restart_guest(); |
1865 | /* Anything else means a bug or incompatible change. */ |
1866 | } else |
1867 | err(1, "Running guest failed"); |
1868 | } |
1869 | } |
1870 | /*L:240 |
1871 | * This is the end of the Launcher. The good news: we are over halfway |
1872 | * through! The bad news: the most fiendish part of the code still lies ahead |
1873 | * of us. |
1874 | * |
1875 | * Are you ready? Take a deep breath and join me in the core of the Host, in |
1876 | * "make Host". |
1877 | :*/ |
1878 | |
1879 | static struct option opts[] = { |
1880 | { "verbose", 0, NULL, 'v' }, |
1881 | { "tunnet", 1, NULL, 't' }, |
1882 | { "block", 1, NULL, 'b' }, |
1883 | { "rng", 0, NULL, 'r' }, |
1884 | { "initrd", 1, NULL, 'i' }, |
1885 | { "username", 1, NULL, 'u' }, |
1886 | { "chroot", 1, NULL, 'c' }, |
1887 | { NULL }, |
1888 | }; |
1889 | static void usage(void) |
1890 | { |
1891 | errx(1, "Usage: lguest [--verbose] " |
1892 | "[--tunnet=(<ipaddr>:<macaddr>|bridge:<bridgename>:<macaddr>)\n" |
1893 | "|--block=<filename>|--initrd=<filename>]...\n" |
1894 | "<mem-in-mb> vmlinux [args...]"); |
1895 | } |
1896 | |
1897 | /*L:105 The main routine is where the real work begins: */ |
1898 | int main(int argc, char *argv[]) |
1899 | { |
1900 | /* Memory, code startpoint and size of the (optional) initrd. */ |
1901 | unsigned long mem = 0, start, initrd_size = 0; |
1902 | /* Two temporaries. */ |
1903 | int i, c; |
1904 | /* The boot information for the Guest. */ |
1905 | struct boot_params *boot; |
1906 | /* If they specify an initrd file to load. */ |
1907 | const char *initrd_name = NULL; |
1908 | |
1909 | /* Password structure for initgroups/setres[gu]id */ |
1910 | struct passwd *user_details = NULL; |
1911 | |
1912 | /* Directory to chroot to */ |
1913 | char *chroot_path = NULL; |
1914 | |
1915 | /* Save the args: we "reboot" by execing ourselves again. */ |
1916 | main_args = argv; |
1917 | |
1918 | /* |
1919 | * First we initialize the device list. We keep a pointer to the last |
1920 | * device, and the next interrupt number to use for devices (1: |
1921 | * remember that 0 is used by the timer). |
1922 | */ |
1923 | devices.lastdev = NULL; |
1924 | devices.next_irq = 1; |
1925 | |
1926 | /* We're CPU 0. In fact, that's the only CPU possible right now. */ |
1927 | cpu_id = 0; |
1928 | |
1929 | /* |
1930 | * We need to know how much memory so we can set up the device |
1931 | * descriptor and memory pages for the devices as we parse the command |
1932 | * line. So we quickly look through the arguments to find the amount |
1933 | * of memory now. |
1934 | */ |
1935 | for (i = 1; i < argc; i++) { |
1936 | if (argv[i][0] != '-') { |
1937 | mem = atoi(argv[i]) * 1024 * 1024; |
1938 | /* |
1939 | * We start by mapping anonymous pages over all of |
1940 | * guest-physical memory range. This fills it with 0, |
1941 | * and ensures that the Guest won't be killed when it |
1942 | * tries to access it. |
1943 | */ |
1944 | guest_base = map_zeroed_pages(mem / getpagesize() |
1945 | + DEVICE_PAGES); |
1946 | guest_limit = mem; |
1947 | guest_max = mem + DEVICE_PAGES*getpagesize(); |
1948 | devices.descpage = get_pages(1); |
1949 | break; |
1950 | } |
1951 | } |
1952 | |
1953 | /* The options are fairly straight-forward */ |
1954 | while ((c = getopt_long(argc, argv, "v", opts, NULL)) != EOF) { |
1955 | switch (c) { |
1956 | case 'v': |
1957 | verbose = true; |
1958 | break; |
1959 | case 't': |
1960 | setup_tun_net(optarg); |
1961 | break; |
1962 | case 'b': |
1963 | setup_block_file(optarg); |
1964 | break; |
1965 | case 'r': |
1966 | setup_rng(); |
1967 | break; |
1968 | case 'i': |
1969 | initrd_name = optarg; |
1970 | break; |
1971 | case 'u': |
1972 | user_details = getpwnam(optarg); |
1973 | if (!user_details) |
1974 | err(1, "getpwnam failed, incorrect username?"); |
1975 | break; |
1976 | case 'c': |
1977 | chroot_path = optarg; |
1978 | break; |
1979 | default: |
1980 | warnx("Unknown argument %s", argv[optind]); |
1981 | usage(); |
1982 | } |
1983 | } |
1984 | /* |
1985 | * After the other arguments we expect memory and kernel image name, |
1986 | * followed by command line arguments for the kernel. |
1987 | */ |
1988 | if (optind + 2 > argc) |
1989 | usage(); |
1990 | |
1991 | verbose("Guest base is at %p\n", guest_base); |
1992 | |
1993 | /* We always have a console device */ |
1994 | setup_console(); |
1995 | |
1996 | /* Now we load the kernel */ |
1997 | start = load_kernel(open_or_die(argv[optind+1], O_RDONLY)); |
1998 | |
1999 | /* Boot information is stashed at physical address 0 */ |
2000 | boot = from_guest_phys(0); |
2001 | |
2002 | /* Map the initrd image if requested (at top of physical memory) */ |
2003 | if (initrd_name) { |
2004 | initrd_size = load_initrd(initrd_name, mem); |
2005 | /* |
2006 | * These are the location in the Linux boot header where the |
2007 | * start and size of the initrd are expected to be found. |
2008 | */ |
2009 | boot->hdr.ramdisk_image = mem - initrd_size; |
2010 | boot->hdr.ramdisk_size = initrd_size; |
2011 | /* The bootloader type 0xFF means "unknown"; that's OK. */ |
2012 | boot->hdr.type_of_loader = 0xFF; |
2013 | } |
2014 | |
2015 | /* |
2016 | * The Linux boot header contains an "E820" memory map: ours is a |
2017 | * simple, single region. |
2018 | */ |
2019 | boot->e820_entries = 1; |
2020 | boot->e820_map[0] = ((struct e820entry) { 0, mem, E820_RAM }); |
2021 | /* |
2022 | * The boot header contains a command line pointer: we put the command |
2023 | * line after the boot header. |
2024 | */ |
2025 | boot->hdr.cmd_line_ptr = to_guest_phys(boot + 1); |
2026 | /* We use a simple helper to copy the arguments separated by spaces. */ |
2027 | concat((char *)(boot + 1), argv+optind+2); |
2028 | |
2029 | /* Boot protocol version: 2.07 supports the fields for lguest. */ |
2030 | boot->hdr.version = 0x207; |
2031 | |
2032 | /* The hardware_subarch value of "1" tells the Guest it's an lguest. */ |
2033 | boot->hdr.hardware_subarch = 1; |
2034 | |
2035 | /* Tell the entry path not to try to reload segment registers. */ |
2036 | boot->hdr.loadflags |= KEEP_SEGMENTS; |
2037 | |
2038 | /* |
2039 | * We tell the kernel to initialize the Guest: this returns the open |
2040 | * /dev/lguest file descriptor. |
2041 | */ |
2042 | tell_kernel(start); |
2043 | |
2044 | /* Ensure that we terminate if a device-servicing child dies. */ |
2045 | signal(SIGCHLD, kill_launcher); |
2046 | |
2047 | /* If we exit via err(), this kills all the threads, restores tty. */ |
2048 | atexit(cleanup_devices); |
2049 | |
2050 | /* If requested, chroot to a directory */ |
2051 | if (chroot_path) { |
2052 | if (chroot(chroot_path) != 0) |
2053 | err(1, "chroot(\"%s\") failed", chroot_path); |
2054 | |
2055 | if (chdir("/") != 0) |
2056 | err(1, "chdir(\"/\") failed"); |
2057 | |
2058 | verbose("chroot done\n"); |
2059 | } |
2060 | |
2061 | /* If requested, drop privileges */ |
2062 | if (user_details) { |
2063 | uid_t u; |
2064 | gid_t g; |
2065 | |
2066 | u = user_details->pw_uid; |
2067 | g = user_details->pw_gid; |
2068 | |
2069 | if (initgroups(user_details->pw_name, g) != 0) |
2070 | err(1, "initgroups failed"); |
2071 | |
2072 | if (setresgid(g, g, g) != 0) |
2073 | err(1, "setresgid failed"); |
2074 | |
2075 | if (setresuid(u, u, u) != 0) |
2076 | err(1, "setresuid failed"); |
2077 | |
2078 | verbose("Dropping privileges completed\n"); |
2079 | } |
2080 | |
2081 | /* Finally, run the Guest. This doesn't return. */ |
2082 | run_guest(); |
2083 | } |
2084 | /*:*/ |
2085 | |
2086 | /*M:999 |
2087 | * Mastery is done: you now know everything I do. |
2088 | * |
2089 | * But surely you have seen code, features and bugs in your wanderings which |
2090 | * you now yearn to attack? That is the real game, and I look forward to you |
2091 | * patching and forking lguest into the Your-Name-Here-visor. |
2092 | * |
2093 | * Farewell, and good coding! |
2094 | * Rusty Russell. |
2095 | */ |
2096 |
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Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
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