devices.c revision fad7204e9eac20a87afacd7547ed8202a39319f8 
1/*
2 * Copyright (C) 2007 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include <errno.h>
18#include <stdio.h>
19#include <stdlib.h>
20#include <sys/stat.h>
21#include <sys/types.h>
22
23#include <fcntl.h>
24#include <dirent.h>
25#include <unistd.h>
26#include <string.h>
27
28#include <sys/socket.h>
29#include <sys/un.h>
30#include <linux/netlink.h>
31#include <private/android_filesystem_config.h>
32#include <sys/time.h>
33#include <asm/page.h>
34#include <sys/wait.h>
35
36#include "devices.h"
37#include "util.h"
38#include "log.h"
39#include "list.h"
40
41#define SYSFS_PREFIX    "/sys"
42#define FIRMWARE_DIR    "/etc/firmware"
43
44static int device_fd = -1;
45
46struct uevent {
47    const char *action;
48    const char *path;
49    const char *subsystem;
50    const char *firmware;
51    const char *partition_name;
52    int partition_num;
53    int major;
54    int minor;
55};
56
57static int open_uevent_socket(void)
58{
59    struct sockaddr_nl addr;
60    int sz = 64*1024; // XXX larger? udev uses 16MB!
61    int on = 1;
62    int s;
63
64    memset(&addr, 0, sizeof(addr));
65    addr.nl_family = AF_NETLINK;
66    addr.nl_pid = getpid();
67    addr.nl_groups = 0xffffffff;
68
69    s = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_KOBJECT_UEVENT);
70    if(s < 0)
71        return -1;
72
73    setsockopt(s, SOL_SOCKET, SO_RCVBUFFORCE, &sz, sizeof(sz));
74    setsockopt(s, SOL_SOCKET, SO_PASSCRED, &on, sizeof(on));
75
76    if(bind(s, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
77        close(s);
78        return -1;
79    }
80
81    return s;
82}
83
84struct perms_ {
85    char *name;
86    mode_t perm;
87    unsigned int uid;
88    unsigned int gid;
89    unsigned short prefix;
90};
91
92struct perm_node {
93    struct perms_ dp;
94    struct listnode plist;
95};
96static list_declare(dev_perms);
97
98/*
99 * Permission override when in emulator mode, must be parsed before
100 * system properties is initalized.
101 */
102int add_dev_perms(const char *name, mode_t perm, unsigned int uid,
103                  unsigned int gid, unsigned short prefix) {
104    int size;
105    char *tmp = 0;
106    struct perm_node *node = malloc(sizeof (struct perm_node));
107    if (!node)
108        return -ENOMEM;
109
110    size = strlen(name) + 1;
111    if ((node->dp.name = malloc(size)) == NULL)
112        return -ENOMEM;
113
114    memcpy(node->dp.name, name, size);
115    node->dp.perm = perm;
116    node->dp.uid = uid;
117    node->dp.gid = gid;
118    node->dp.prefix = prefix;
119
120    list_add_tail(&dev_perms, &node->plist);
121    return 0;
122}
123
124static int get_device_perm_inner(struct perms_ *perms, const char *path,
125                                    unsigned *uid, unsigned *gid, mode_t *perm)
126{
127    int i;
128    for(i = 0; perms[i].name; i++) {
129
130        if(perms[i].prefix) {
131            if(strncmp(path, perms[i].name, strlen(perms[i].name)))
132                continue;
133        } else {
134            if(strcmp(path, perms[i].name))
135                continue;
136        }
137        *uid = perms[i].uid;
138        *gid = perms[i].gid;
139        *perm = perms[i].perm;
140        return 0;
141    }
142    return -1;
143}
144
145/* First checks for emulator specific permissions specified in /proc/cmdline. */
146static mode_t get_device_perm(const char *path, unsigned *uid, unsigned *gid)
147{
148    mode_t perm;
149    struct listnode *node;
150    struct perm_node *perm_node;
151    struct perms_ *dp;
152
153    /* search the perms list in reverse so that ueventd.$hardware can
154     * override ueventd.rc
155     */
156    list_for_each_reverse(node, &dev_perms) {
157        perm_node = node_to_item(node, struct perm_node, plist);
158        dp = &perm_node->dp;
159
160        if (dp->prefix) {
161            if (strncmp(path, dp->name, strlen(dp->name)))
162                continue;
163        } else {
164            if (strcmp(path, dp->name))
165                continue;
166        }
167        *uid = dp->uid;
168        *gid = dp->gid;
169        return dp->perm;
170    }
171    /* Default if nothing found. */
172    *uid = 0;
173    *gid = 0;
174    return 0600;
175}
176
177static void make_device(const char *path, int block, int major, int minor)
178{
179    unsigned uid;
180    unsigned gid;
181    mode_t mode;
182    dev_t dev;
183
184    if(major > 255 || minor > 255)
185        return;
186
187    mode = get_device_perm(path, &uid, &gid) | (block ? S_IFBLK : S_IFCHR);
188    dev = (major << 8) | minor;
189    /* Temporarily change egid to avoid race condition setting the gid of the
190     * device node. Unforunately changing the euid would prevent creation of
191     * some device nodes, so the uid has to be set with chown() and is still
192     * racy. Fixing the gid race at least fixed the issue with system_server
193     * opening dynamic input devices under the AID_INPUT gid. */
194    setegid(gid);
195    mknod(path, mode, dev);
196    chown(path, uid, -1);
197    setegid(AID_ROOT);
198}
199
200#if LOG_UEVENTS
201
202static inline suseconds_t get_usecs(void)
203{
204    struct timeval tv;
205    gettimeofday(&tv, 0);
206    return tv.tv_sec * (suseconds_t) 1000000 + tv.tv_usec;
207}
208
209#define log_event_print(x...) INFO(x)
210
211#else
212
213#define log_event_print(fmt, args...)   do { } while (0)
214#define get_usecs()                     0
215
216#endif
217
218static void parse_event(const char *msg, struct uevent *uevent)
219{
220    uevent->action = "";
221    uevent->path = "";
222    uevent->subsystem = "";
223    uevent->firmware = "";
224    uevent->major = -1;
225    uevent->minor = -1;
226    uevent->partition_name = NULL;
227    uevent->partition_num = -1;
228
229        /* currently ignoring SEQNUM */
230    while(*msg) {
231        if(!strncmp(msg, "ACTION=", 7)) {
232            msg += 7;
233            uevent->action = msg;
234        } else if(!strncmp(msg, "DEVPATH=", 8)) {
235            msg += 8;
236            uevent->path = msg;
237        } else if(!strncmp(msg, "SUBSYSTEM=", 10)) {
238            msg += 10;
239            uevent->subsystem = msg;
240        } else if(!strncmp(msg, "FIRMWARE=", 9)) {
241            msg += 9;
242            uevent->firmware = msg;
243        } else if(!strncmp(msg, "MAJOR=", 6)) {
244            msg += 6;
245            uevent->major = atoi(msg);
246        } else if(!strncmp(msg, "MINOR=", 6)) {
247            msg += 6;
248            uevent->minor = atoi(msg);
249        } else if(!strncmp(msg, "PARTN=", 6)) {
250            msg += 6;
251            uevent->partition_num = atoi(msg);
252        } else if(!strncmp(msg, "PARTNAME=", 9)) {
253            msg += 9;
254            uevent->partition_name = msg;
255        }
256
257            /* advance to after the next \0 */
258        while(*msg++)
259            ;
260    }
261
262    log_event_print("event { '%s', '%s', '%s', '%s', %d, %d }\n",
263                    uevent->action, uevent->path, uevent->subsystem,
264                    uevent->firmware, uevent->major, uevent->minor);
265}
266
267static char **parse_platform_block_device(struct uevent *uevent)
268{
269    const char *driver;
270    const char *path;
271    char *slash;
272    int width;
273    char buf[256];
274    char link_path[256];
275    int fd;
276    int link_num = 0;
277    int ret;
278    char *p;
279    unsigned int size;
280    struct stat info;
281
282    char **links = malloc(sizeof(char *) * 4);
283    if (!links)
284        return NULL;
285    memset(links, 0, sizeof(char *) * 4);
286
287    /* Drop "/devices/platform/" */
288    path = uevent->path;
289    driver = path + 18;
290    slash = strchr(driver, '/');
291    if (!slash)
292        goto err;
293    width = slash - driver;
294    if (width <= 0)
295        goto err;
296
297    snprintf(link_path, sizeof(link_path), "/dev/block/platform/%.*s",
298             width, driver);
299
300    if (uevent->partition_name) {
301        p = strdup(uevent->partition_name);
302        sanitize(p);
303        if (asprintf(&links[link_num], "%s/by-name/%s", link_path, p) > 0)
304            link_num++;
305        else
306            links[link_num] = NULL;
307        free(p);
308    }
309
310    if (uevent->partition_num >= 0) {
311        if (asprintf(&links[link_num], "%s/by-num/p%d", link_path, uevent->partition_num) > 0)
312            link_num++;
313        else
314            links[link_num] = NULL;
315    }
316
317    slash = strrchr(path, '/');
318    if (asprintf(&links[link_num], "%s/%s", link_path, slash + 1) > 0)
319        link_num++;
320    else
321        links[link_num] = NULL;
322
323    return links;
324
325err:
326    free(links);
327    return NULL;
328}
329
330static void handle_device_event(struct uevent *uevent)
331{
332    char devpath[96];
333    int devpath_ready = 0;
334    char *base, *name;
335    char **links = NULL;
336    int block;
337    int i;
338
339        /* if it's not a /dev device, nothing to do */
340    if((uevent->major < 0) || (uevent->minor < 0))
341        return;
342
343        /* do we have a name? */
344    name = strrchr(uevent->path, '/');
345    if(!name)
346        return;
347    name++;
348
349        /* too-long names would overrun our buffer */
350    if(strlen(name) > 64)
351        return;
352
353        /* are we block or char? where should we live? */
354    if(!strncmp(uevent->subsystem, "block", 5)) {
355        block = 1;
356        base = "/dev/block/";
357        mkdir(base, 0755);
358        if (!strncmp(uevent->path, "/devices/platform/", 18))
359            links = parse_platform_block_device(uevent);
360    } else {
361        block = 0;
362            /* this should probably be configurable somehow */
363        if (!strncmp(uevent->subsystem, "usb", 3)) {
364            if (!strcmp(uevent->subsystem, "usb")) {
365                /* This imitates the file system that would be created
366                 * if we were using devfs instead.
367                 * Minors are broken up into groups of 128, starting at "001"
368                 */
369                int bus_id = uevent->minor / 128 + 1;
370                int device_id = uevent->minor % 128 + 1;
371                /* build directories */
372                mkdir("/dev/bus", 0755);
373                mkdir("/dev/bus/usb", 0755);
374                snprintf(devpath, sizeof(devpath), "/dev/bus/usb/%03d", bus_id);
375                mkdir(devpath, 0755);
376                snprintf(devpath, sizeof(devpath), "/dev/bus/usb/%03d/%03d", bus_id, device_id);
377                devpath_ready = 1;
378            } else {
379                /* ignore other USB events */
380                return;
381            }
382        } else if (!strncmp(uevent->subsystem, "graphics", 8)) {
383            base = "/dev/graphics/";
384            mkdir(base, 0755);
385        } else if (!strncmp(uevent->subsystem, "oncrpc", 6)) {
386            base = "/dev/oncrpc/";
387            mkdir(base, 0755);
388        } else if (!strncmp(uevent->subsystem, "adsp", 4)) {
389            base = "/dev/adsp/";
390            mkdir(base, 0755);
391        } else if (!strncmp(uevent->subsystem, "msm_camera", 10)) {
392            base = "/dev/msm_camera/";
393            mkdir(base, 0755);
394        } else if(!strncmp(uevent->subsystem, "input", 5)) {
395            base = "/dev/input/";
396            mkdir(base, 0755);
397        } else if(!strncmp(uevent->subsystem, "mtd", 3)) {
398            base = "/dev/mtd/";
399            mkdir(base, 0755);
400        } else if(!strncmp(uevent->subsystem, "sound", 5)) {
401            base = "/dev/snd/";
402            mkdir(base, 0755);
403        } else if(!strncmp(uevent->subsystem, "misc", 4) &&
404                    !strncmp(name, "log_", 4)) {
405            base = "/dev/log/";
406            mkdir(base, 0755);
407            name += 4;
408        } else
409            base = "/dev/";
410    }
411
412    if (!devpath_ready)
413        snprintf(devpath, sizeof(devpath), "%s%s", base, name);
414
415    if(!strcmp(uevent->action, "add")) {
416        make_device(devpath, block, uevent->major, uevent->minor);
417        if (links) {
418            for (i = 0; links[i]; i++)
419                make_link(devpath, links[i]);
420        }
421    }
422
423    if(!strcmp(uevent->action, "remove")) {
424        if (links) {
425            for (i = 0; links[i]; i++)
426                remove_link(devpath, links[i]);
427        }
428        unlink(devpath);
429    }
430
431    if (links) {
432        for (i = 0; links[i]; i++)
433            free(links[i]);
434        free(links);
435    }
436}
437
438static int load_firmware(int fw_fd, int loading_fd, int data_fd)
439{
440    struct stat st;
441    long len_to_copy;
442    int ret = 0;
443
444    if(fstat(fw_fd, &st) < 0)
445        return -1;
446    len_to_copy = st.st_size;
447
448    write(loading_fd, "1", 1);  /* start transfer */
449
450    while (len_to_copy > 0) {
451        char buf[PAGE_SIZE];
452        ssize_t nr;
453
454        nr = read(fw_fd, buf, sizeof(buf));
455        if(!nr)
456            break;
457        if(nr < 0) {
458            ret = -1;
459            break;
460        }
461
462        len_to_copy -= nr;
463        while (nr > 0) {
464            ssize_t nw = 0;
465
466            nw = write(data_fd, buf + nw, nr);
467            if(nw <= 0) {
468                ret = -1;
469                goto out;
470            }
471            nr -= nw;
472        }
473    }
474
475out:
476    if(!ret)
477        write(loading_fd, "0", 1);  /* successful end of transfer */
478    else
479        write(loading_fd, "-1", 2); /* abort transfer */
480
481    return ret;
482}
483
484static void process_firmware_event(struct uevent *uevent)
485{
486    char *root, *loading, *data, *file;
487    int l, loading_fd, data_fd, fw_fd;
488
489    log_event_print("firmware event { '%s', '%s' }\n",
490                    uevent->path, uevent->firmware);
491
492    l = asprintf(&root, SYSFS_PREFIX"%s/", uevent->path);
493    if (l == -1)
494        return;
495
496    l = asprintf(&loading, "%sloading", root);
497    if (l == -1)
498        goto root_free_out;
499
500    l = asprintf(&data, "%sdata", root);
501    if (l == -1)
502        goto loading_free_out;
503
504    l = asprintf(&file, FIRMWARE_DIR"/%s", uevent->firmware);
505    if (l == -1)
506        goto data_free_out;
507
508    loading_fd = open(loading, O_WRONLY);
509    if(loading_fd < 0)
510        goto file_free_out;
511
512    data_fd = open(data, O_WRONLY);
513    if(data_fd < 0)
514        goto loading_close_out;
515
516    fw_fd = open(file, O_RDONLY);
517    if(fw_fd < 0)
518        goto data_close_out;
519
520    if(!load_firmware(fw_fd, loading_fd, data_fd))
521        log_event_print("firmware copy success { '%s', '%s' }\n", root, file);
522    else
523        log_event_print("firmware copy failure { '%s', '%s' }\n", root, file);
524
525    close(fw_fd);
526data_close_out:
527    close(data_fd);
528loading_close_out:
529    close(loading_fd);
530file_free_out:
531    free(file);
532data_free_out:
533    free(data);
534loading_free_out:
535    free(loading);
536root_free_out:
537    free(root);
538}
539
540static void handle_firmware_event(struct uevent *uevent)
541{
542    pid_t pid;
543    int status;
544    int ret;
545
546    if(strcmp(uevent->subsystem, "firmware"))
547        return;
548
549    if(strcmp(uevent->action, "add"))
550        return;
551
552    /* we fork, to avoid making large memory allocations in init proper */
553    pid = fork();
554    if (!pid) {
555        process_firmware_event(uevent);
556        exit(EXIT_SUCCESS);
557    } else {
558        do {
559            ret = waitpid(pid, &status, 0);
560        } while (ret == -1 && errno == EINTR);
561    }
562}
563
564#define UEVENT_MSG_LEN  1024
565void handle_device_fd()
566{
567    for(;;) {
568        char msg[UEVENT_MSG_LEN+2];
569        char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
570        struct iovec iov = {msg, sizeof(msg)};
571        struct sockaddr_nl snl;
572        struct msghdr hdr = {&snl, sizeof(snl), &iov, 1, cred_msg, sizeof(cred_msg), 0};
573
574        ssize_t n = recvmsg(device_fd, &hdr, 0);
575        if (n <= 0) {
576            break;
577        }
578
579        if ((snl.nl_groups != 1) || (snl.nl_pid != 0)) {
580            /* ignoring non-kernel netlink multicast message */
581            continue;
582        }
583
584        struct cmsghdr * cmsg = CMSG_FIRSTHDR(&hdr);
585        if (cmsg == NULL || cmsg->cmsg_type != SCM_CREDENTIALS) {
586            /* no sender credentials received, ignore message */
587            continue;
588        }
589
590        struct ucred * cred = (struct ucred *)CMSG_DATA(cmsg);
591        if (cred->uid != 0) {
592            /* message from non-root user, ignore */
593            continue;
594        }
595
596        if(n >= UEVENT_MSG_LEN)   /* overflow -- discard */
597            continue;
598
599        msg[n] = '\0';
600        msg[n+1] = '\0';
601
602        struct uevent uevent;
603        parse_event(msg, &uevent);
604
605        handle_device_event(&uevent);
606        handle_firmware_event(&uevent);
607    }
608}
609
610/* Coldboot walks parts of the /sys tree and pokes the uevent files
611** to cause the kernel to regenerate device add events that happened
612** before init's device manager was started
613**
614** We drain any pending events from the netlink socket every time
615** we poke another uevent file to make sure we don't overrun the
616** socket's buffer.
617*/
618
619static void do_coldboot(DIR *d)
620{
621    struct dirent *de;
622    int dfd, fd;
623
624    dfd = dirfd(d);
625
626    fd = openat(dfd, "uevent", O_WRONLY);
627    if(fd >= 0) {
628        write(fd, "add\n", 4);
629        close(fd);
630        handle_device_fd();
631    }
632
633    while((de = readdir(d))) {
634        DIR *d2;
635
636        if(de->d_type != DT_DIR || de->d_name[0] == '.')
637            continue;
638
639        fd = openat(dfd, de->d_name, O_RDONLY | O_DIRECTORY);
640        if(fd < 0)
641            continue;
642
643        d2 = fdopendir(fd);
644        if(d2 == 0)
645            close(fd);
646        else {
647            do_coldboot(d2);
648            closedir(d2);
649        }
650    }
651}
652
653static void coldboot(const char *path)
654{
655    DIR *d = opendir(path);
656    if(d) {
657        do_coldboot(d);
658        closedir(d);
659    }
660}
661
662void device_init(void)
663{
664    suseconds_t t0, t1;
665    struct stat info;
666    int fd;
667
668    device_fd = open_uevent_socket();
669    if(device_fd < 0)
670        return;
671
672    fcntl(device_fd, F_SETFD, FD_CLOEXEC);
673    fcntl(device_fd, F_SETFL, O_NONBLOCK);
674
675    if (stat(coldboot_done, &info) < 0) {
676        t0 = get_usecs();
677        coldboot("/sys/class");
678        coldboot("/sys/block");
679        coldboot("/sys/devices");
680        t1 = get_usecs();
681        fd = open(coldboot_done, O_WRONLY|O_CREAT, 0000);
682        close(fd);
683        log_event_print("coldboot %ld uS\n", ((long) (t1 - t0)));
684    } else {
685        log_event_print("skipping coldboot, already done\n");
686    }
687}
688
689int get_device_fd()
690{
691    return device_fd;
692}
693