devices.c revision d2278638d6b37717b51d622929eb4c8f6e16cb0c 
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 **get_character_device_symlinks(struct uevent *uevent)
268{
269    const char *parent;
270    char *slash;
271    char **links;
272    int link_num = 0;
273    int width;
274
275    if (strncmp(uevent->path, "/devices/platform/", 18))
276        return NULL;
277
278    links = malloc(sizeof(char *) * 2);
279    if (!links)
280        return NULL;
281    memset(links, 0, sizeof(char *) * 2);
282
283    /* skip "/devices/platform/<driver>" */
284    parent = strchr(uevent->path + 18, '/');
285    if (!*parent)
286        goto err;
287
288    if (!strncmp(parent, "/usb", 4)) {
289        /* skip root hub name and device. use device interface */
290        while (*++parent && *parent != '/');
291        if (*parent)
292            while (*++parent && *parent != '/');
293        if (!*parent)
294            goto err;
295        slash = strchr(++parent, '/');
296        if (!slash)
297            goto err;
298        width = slash - parent;
299        if (width <= 0)
300            goto err;
301
302        if (asprintf(&links[link_num], "/dev/usb/%s%.*s", uevent->subsystem, width, parent) > 0)
303            link_num++;
304        else
305            links[link_num] = NULL;
306        mkdir("/dev/usb", 0755);
307    }
308    else {
309        goto err;
310    }
311
312    return links;
313err:
314    free(links);
315    return NULL;
316}
317
318static char **parse_platform_block_device(struct uevent *uevent)
319{
320    const char *driver;
321    const char *path;
322    char *slash;
323    int width;
324    char buf[256];
325    char link_path[256];
326    int fd;
327    int link_num = 0;
328    int ret;
329    char *p;
330    unsigned int size;
331    struct stat info;
332
333    char **links = malloc(sizeof(char *) * 4);
334    if (!links)
335        return NULL;
336    memset(links, 0, sizeof(char *) * 4);
337
338    /* Drop "/devices/platform/" */
339    path = uevent->path;
340    driver = path + 18;
341    slash = strchr(driver, '/');
342    if (!slash)
343        goto err;
344    width = slash - driver;
345    if (width <= 0)
346        goto err;
347
348    snprintf(link_path, sizeof(link_path), "/dev/block/platform/%.*s",
349             width, driver);
350
351    if (uevent->partition_name) {
352        p = strdup(uevent->partition_name);
353        sanitize(p);
354        if (asprintf(&links[link_num], "%s/by-name/%s", link_path, p) > 0)
355            link_num++;
356        else
357            links[link_num] = NULL;
358        free(p);
359    }
360
361    if (uevent->partition_num >= 0) {
362        if (asprintf(&links[link_num], "%s/by-num/p%d", link_path, uevent->partition_num) > 0)
363            link_num++;
364        else
365            links[link_num] = NULL;
366    }
367
368    slash = strrchr(path, '/');
369    if (asprintf(&links[link_num], "%s/%s", link_path, slash + 1) > 0)
370        link_num++;
371    else
372        links[link_num] = NULL;
373
374    return links;
375
376err:
377    free(links);
378    return NULL;
379}
380
381static void handle_device_event(struct uevent *uevent)
382{
383    char devpath[96];
384    int devpath_ready = 0;
385    char *base, *name;
386    char **links = NULL;
387    int block;
388    int i;
389
390        /* if it's not a /dev device, nothing to do */
391    if((uevent->major < 0) || (uevent->minor < 0))
392        return;
393
394        /* do we have a name? */
395    name = strrchr(uevent->path, '/');
396    if(!name)
397        return;
398    name++;
399
400        /* too-long names would overrun our buffer */
401    if(strlen(name) > 64)
402        return;
403
404        /* are we block or char? where should we live? */
405    if(!strncmp(uevent->subsystem, "block", 5)) {
406        block = 1;
407        base = "/dev/block/";
408        mkdir(base, 0755);
409        if (!strncmp(uevent->path, "/devices/platform/", 18))
410            links = parse_platform_block_device(uevent);
411    } else {
412        block = 0;
413            /* this should probably be configurable somehow */
414        if (!strncmp(uevent->subsystem, "usb", 3)) {
415            if (!strcmp(uevent->subsystem, "usb")) {
416                /* This imitates the file system that would be created
417                 * if we were using devfs instead.
418                 * Minors are broken up into groups of 128, starting at "001"
419                 */
420                int bus_id = uevent->minor / 128 + 1;
421                int device_id = uevent->minor % 128 + 1;
422                /* build directories */
423                mkdir("/dev/bus", 0755);
424                mkdir("/dev/bus/usb", 0755);
425                snprintf(devpath, sizeof(devpath), "/dev/bus/usb/%03d", bus_id);
426                mkdir(devpath, 0755);
427                snprintf(devpath, sizeof(devpath), "/dev/bus/usb/%03d/%03d", bus_id, device_id);
428                devpath_ready = 1;
429            } else {
430                /* ignore other USB events */
431                return;
432            }
433        } else if (!strncmp(uevent->subsystem, "graphics", 8)) {
434            base = "/dev/graphics/";
435            mkdir(base, 0755);
436        } else if (!strncmp(uevent->subsystem, "oncrpc", 6)) {
437            base = "/dev/oncrpc/";
438            mkdir(base, 0755);
439        } else if (!strncmp(uevent->subsystem, "adsp", 4)) {
440            base = "/dev/adsp/";
441            mkdir(base, 0755);
442        } else if (!strncmp(uevent->subsystem, "msm_camera", 10)) {
443            base = "/dev/msm_camera/";
444            mkdir(base, 0755);
445        } else if(!strncmp(uevent->subsystem, "input", 5)) {
446            base = "/dev/input/";
447            mkdir(base, 0755);
448        } else if(!strncmp(uevent->subsystem, "mtd", 3)) {
449            base = "/dev/mtd/";
450            mkdir(base, 0755);
451        } else if(!strncmp(uevent->subsystem, "sound", 5)) {
452            base = "/dev/snd/";
453            mkdir(base, 0755);
454        } else if(!strncmp(uevent->subsystem, "misc", 4) &&
455                    !strncmp(name, "log_", 4)) {
456            base = "/dev/log/";
457            mkdir(base, 0755);
458            name += 4;
459        } else
460            base = "/dev/";
461        links = get_character_device_symlinks(uevent);
462    }
463
464    if (!devpath_ready)
465        snprintf(devpath, sizeof(devpath), "%s%s", base, name);
466
467    if(!strcmp(uevent->action, "add")) {
468        make_device(devpath, block, uevent->major, uevent->minor);
469        if (links) {
470            for (i = 0; links[i]; i++)
471                make_link(devpath, links[i]);
472        }
473    }
474
475    if(!strcmp(uevent->action, "remove")) {
476        if (links) {
477            for (i = 0; links[i]; i++)
478                remove_link(devpath, links[i]);
479        }
480        unlink(devpath);
481    }
482
483    if (links) {
484        for (i = 0; links[i]; i++)
485            free(links[i]);
486        free(links);
487    }
488}
489
490static int load_firmware(int fw_fd, int loading_fd, int data_fd)
491{
492    struct stat st;
493    long len_to_copy;
494    int ret = 0;
495
496    if(fstat(fw_fd, &st) < 0)
497        return -1;
498    len_to_copy = st.st_size;
499
500    write(loading_fd, "1", 1);  /* start transfer */
501
502    while (len_to_copy > 0) {
503        char buf[PAGE_SIZE];
504        ssize_t nr;
505
506        nr = read(fw_fd, buf, sizeof(buf));
507        if(!nr)
508            break;
509        if(nr < 0) {
510            ret = -1;
511            break;
512        }
513
514        len_to_copy -= nr;
515        while (nr > 0) {
516            ssize_t nw = 0;
517
518            nw = write(data_fd, buf + nw, nr);
519            if(nw <= 0) {
520                ret = -1;
521                goto out;
522            }
523            nr -= nw;
524        }
525    }
526
527out:
528    if(!ret)
529        write(loading_fd, "0", 1);  /* successful end of transfer */
530    else
531        write(loading_fd, "-1", 2); /* abort transfer */
532
533    return ret;
534}
535
536static void process_firmware_event(struct uevent *uevent)
537{
538    char *root, *loading, *data, *file;
539    int l, loading_fd, data_fd, fw_fd;
540
541    log_event_print("firmware event { '%s', '%s' }\n",
542                    uevent->path, uevent->firmware);
543
544    l = asprintf(&root, SYSFS_PREFIX"%s/", uevent->path);
545    if (l == -1)
546        return;
547
548    l = asprintf(&loading, "%sloading", root);
549    if (l == -1)
550        goto root_free_out;
551
552    l = asprintf(&data, "%sdata", root);
553    if (l == -1)
554        goto loading_free_out;
555
556    l = asprintf(&file, FIRMWARE_DIR"/%s", uevent->firmware);
557    if (l == -1)
558        goto data_free_out;
559
560    loading_fd = open(loading, O_WRONLY);
561    if(loading_fd < 0)
562        goto file_free_out;
563
564    data_fd = open(data, O_WRONLY);
565    if(data_fd < 0)
566        goto loading_close_out;
567
568    fw_fd = open(file, O_RDONLY);
569    if(fw_fd < 0)
570        goto data_close_out;
571
572    if(!load_firmware(fw_fd, loading_fd, data_fd))
573        log_event_print("firmware copy success { '%s', '%s' }\n", root, file);
574    else
575        log_event_print("firmware copy failure { '%s', '%s' }\n", root, file);
576
577    close(fw_fd);
578data_close_out:
579    close(data_fd);
580loading_close_out:
581    close(loading_fd);
582file_free_out:
583    free(file);
584data_free_out:
585    free(data);
586loading_free_out:
587    free(loading);
588root_free_out:
589    free(root);
590}
591
592static void handle_firmware_event(struct uevent *uevent)
593{
594    pid_t pid;
595    int status;
596    int ret;
597
598    if(strcmp(uevent->subsystem, "firmware"))
599        return;
600
601    if(strcmp(uevent->action, "add"))
602        return;
603
604    /* we fork, to avoid making large memory allocations in init proper */
605    pid = fork();
606    if (!pid) {
607        process_firmware_event(uevent);
608        exit(EXIT_SUCCESS);
609    } else {
610        do {
611            ret = waitpid(pid, &status, 0);
612        } while (ret == -1 && errno == EINTR);
613    }
614}
615
616#define UEVENT_MSG_LEN  1024
617void handle_device_fd()
618{
619    for(;;) {
620        char msg[UEVENT_MSG_LEN+2];
621        char cred_msg[CMSG_SPACE(sizeof(struct ucred))];
622        struct iovec iov = {msg, sizeof(msg)};
623        struct sockaddr_nl snl;
624        struct msghdr hdr = {&snl, sizeof(snl), &iov, 1, cred_msg, sizeof(cred_msg), 0};
625
626        ssize_t n = recvmsg(device_fd, &hdr, 0);
627        if (n <= 0) {
628            break;
629        }
630
631        if ((snl.nl_groups != 1) || (snl.nl_pid != 0)) {
632            /* ignoring non-kernel netlink multicast message */
633            continue;
634        }
635
636        struct cmsghdr * cmsg = CMSG_FIRSTHDR(&hdr);
637        if (cmsg == NULL || cmsg->cmsg_type != SCM_CREDENTIALS) {
638            /* no sender credentials received, ignore message */
639            continue;
640        }
641
642        struct ucred * cred = (struct ucred *)CMSG_DATA(cmsg);
643        if (cred->uid != 0) {
644            /* message from non-root user, ignore */
645            continue;
646        }
647
648        if(n >= UEVENT_MSG_LEN)   /* overflow -- discard */
649            continue;
650
651        msg[n] = '\0';
652        msg[n+1] = '\0';
653
654        struct uevent uevent;
655        parse_event(msg, &uevent);
656
657        handle_device_event(&uevent);
658        handle_firmware_event(&uevent);
659    }
660}
661
662/* Coldboot walks parts of the /sys tree and pokes the uevent files
663** to cause the kernel to regenerate device add events that happened
664** before init's device manager was started
665**
666** We drain any pending events from the netlink socket every time
667** we poke another uevent file to make sure we don't overrun the
668** socket's buffer.
669*/
670
671static void do_coldboot(DIR *d)
672{
673    struct dirent *de;
674    int dfd, fd;
675
676    dfd = dirfd(d);
677
678    fd = openat(dfd, "uevent", O_WRONLY);
679    if(fd >= 0) {
680        write(fd, "add\n", 4);
681        close(fd);
682        handle_device_fd();
683    }
684
685    while((de = readdir(d))) {
686        DIR *d2;
687
688        if(de->d_type != DT_DIR || de->d_name[0] == '.')
689            continue;
690
691        fd = openat(dfd, de->d_name, O_RDONLY | O_DIRECTORY);
692        if(fd < 0)
693            continue;
694
695        d2 = fdopendir(fd);
696        if(d2 == 0)
697            close(fd);
698        else {
699            do_coldboot(d2);
700            closedir(d2);
701        }
702    }
703}
704
705static void coldboot(const char *path)
706{
707    DIR *d = opendir(path);
708    if(d) {
709        do_coldboot(d);
710        closedir(d);
711    }
712}
713
714void device_init(void)
715{
716    suseconds_t t0, t1;
717    struct stat info;
718    int fd;
719
720    device_fd = open_uevent_socket();
721    if(device_fd < 0)
722        return;
723
724    fcntl(device_fd, F_SETFD, FD_CLOEXEC);
725    fcntl(device_fd, F_SETFL, O_NONBLOCK);
726
727    if (stat(coldboot_done, &info) < 0) {
728        t0 = get_usecs();
729        coldboot("/sys/class");
730        coldboot("/sys/block");
731        coldboot("/sys/devices");
732        t1 = get_usecs();
733        fd = open(coldboot_done, O_WRONLY|O_CREAT, 0000);
734        close(fd);
735        log_event_print("coldboot %ld uS\n", ((long) (t1 - t0)));
736    } else {
737        log_event_print("skipping coldboot, already done\n");
738    }
739}
740
741int get_device_fd()
742{
743    return device_fd;
744}
745