devices.cpp revision d4ff8d83d3fcc23c07d928f8d463a54aa584e739 
1/*
2 * Copyright (C) 2007-2014 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 <dirent.h>
18#include <errno.h>
19#include <fcntl.h>
20#include <fnmatch.h>
21#include <libgen.h>
22#include <linux/netlink.h>
23#include <stddef.h>
24#include <stdio.h>
25#include <stdlib.h>
26#include <string.h>
27#include <sys/sendfile.h>
28#include <sys/socket.h>
29#include <sys/time.h>
30#include <sys/types.h>
31#include <sys/un.h>
32#include <sys/wait.h>
33#include <unistd.h>
34
35#include <memory>
36#include <thread>
37
38#include <android-base/file.h>
39#include <android-base/logging.h>
40#include <android-base/stringprintf.h>
41#include <android-base/unique_fd.h>
42#include <cutils/list.h>
43#include <cutils/uevent.h>
44#include <private/android_filesystem_config.h>
45#include <selinux/android.h>
46#include <selinux/avc.h>
47#include <selinux/label.h>
48#include <selinux/selinux.h>
49
50#include "devices.h"
51#include "ueventd_parser.h"
52#include "util.h"
53
54#define SYSFS_PREFIX    "/sys"
55static const char *firmware_dirs[] = { "/etc/firmware",
56                                       "/vendor/firmware",
57                                       "/firmware/image" };
58
59extern struct selabel_handle *sehandle;
60
61static android::base::unique_fd device_fd;
62
63struct perms_ {
64    char *name;
65    char *attr;
66    mode_t perm;
67    unsigned int uid;
68    unsigned int gid;
69    unsigned short prefix;
70    unsigned short wildcard;
71};
72
73struct perm_node {
74    struct perms_ dp;
75    struct listnode plist;
76};
77
78struct platform_node {
79    char *name;
80    char *path;
81    int path_len;
82    struct listnode list;
83};
84
85static list_declare(sys_perms);
86static list_declare(dev_perms);
87static list_declare(platform_names);
88
89int add_dev_perms(const char *name, const char *attr,
90                  mode_t perm, unsigned int uid, unsigned int gid,
91                  unsigned short prefix,
92                  unsigned short wildcard) {
93    struct perm_node *node = (perm_node*) calloc(1, sizeof(*node));
94    if (!node)
95        return -ENOMEM;
96
97    node->dp.name = strdup(name);
98    if (!node->dp.name) {
99        free(node);
100        return -ENOMEM;
101    }
102
103    if (attr) {
104        node->dp.attr = strdup(attr);
105        if (!node->dp.attr) {
106            free(node->dp.name);
107            free(node);
108            return -ENOMEM;
109        }
110    }
111
112    node->dp.perm = perm;
113    node->dp.uid = uid;
114    node->dp.gid = gid;
115    node->dp.prefix = prefix;
116    node->dp.wildcard = wildcard;
117
118    if (attr)
119        list_add_tail(&sys_perms, &node->plist);
120    else
121        list_add_tail(&dev_perms, &node->plist);
122
123    return 0;
124}
125
126static bool perm_path_matches(const char *path, struct perms_ *dp)
127{
128    if (dp->prefix) {
129        if (strncmp(path, dp->name, strlen(dp->name)) == 0)
130            return true;
131    } else if (dp->wildcard) {
132        if (fnmatch(dp->name, path, FNM_PATHNAME) == 0)
133            return true;
134    } else {
135        if (strcmp(path, dp->name) == 0)
136            return true;
137    }
138
139    return false;
140}
141
142static bool match_subsystem(perms_* dp, const char* pattern,
143                            const char* path, const char* subsystem) {
144    if (!pattern || !subsystem || strstr(dp->name, subsystem) == NULL) {
145        return false;
146    }
147
148    std::string subsys_path = android::base::StringPrintf(pattern, subsystem, basename(path));
149    return perm_path_matches(subsys_path.c_str(), dp);
150}
151
152static void fixup_sys_perms(const char* upath, const char* subsystem) {
153    // upaths omit the "/sys" that paths in this list
154    // contain, so we prepend it...
155    std::string path = std::string(SYSFS_PREFIX) + upath;
156
157    listnode* node;
158    list_for_each(node, &sys_perms) {
159        perms_* dp = &(node_to_item(node, perm_node, plist))->dp;
160        if (match_subsystem(dp, SYSFS_PREFIX "/class/%s/%s", path.c_str(), subsystem)) {
161            ; // matched
162        } else if (match_subsystem(dp, SYSFS_PREFIX "/bus/%s/devices/%s", path.c_str(), subsystem)) {
163            ; // matched
164        } else if (!perm_path_matches(path.c_str(), dp)) {
165            continue;
166        }
167
168        std::string attr_file = path + "/" + dp->attr;
169        LOG(INFO) << "fixup " << attr_file
170                  << " " << dp->uid << " " << dp->gid << " " << std::oct << dp->perm;
171        chown(attr_file.c_str(), dp->uid, dp->gid);
172        chmod(attr_file.c_str(), dp->perm);
173    }
174
175    if (access(path.c_str(), F_OK) == 0) {
176        LOG(VERBOSE) << "restorecon_recursive: " << path;
177        restorecon(path.c_str(), SELINUX_ANDROID_RESTORECON_RECURSE);
178    }
179}
180
181static mode_t get_device_perm(const char *path, const char **links,
182                unsigned *uid, unsigned *gid)
183{
184    struct listnode *node;
185    struct perm_node *perm_node;
186    struct perms_ *dp;
187
188    /* search the perms list in reverse so that ueventd.$hardware can
189     * override ueventd.rc
190     */
191    list_for_each_reverse(node, &dev_perms) {
192        bool match = false;
193
194        perm_node = node_to_item(node, struct perm_node, plist);
195        dp = &perm_node->dp;
196
197        if (perm_path_matches(path, dp)) {
198            match = true;
199        } else {
200            if (links) {
201                int i;
202                for (i = 0; links[i]; i++) {
203                    if (perm_path_matches(links[i], dp)) {
204                        match = true;
205                        break;
206                    }
207                }
208            }
209        }
210
211        if (match) {
212            *uid = dp->uid;
213            *gid = dp->gid;
214            return dp->perm;
215        }
216    }
217    /* Default if nothing found. */
218    *uid = 0;
219    *gid = 0;
220    return 0600;
221}
222
223static void make_device(const char *path,
224                        const char */*upath*/,
225                        int block, int major, int minor,
226                        const char **links)
227{
228    unsigned uid;
229    unsigned gid;
230    mode_t mode;
231    dev_t dev;
232    char *secontext = NULL;
233
234    mode = get_device_perm(path, links, &uid, &gid) | (block ? S_IFBLK : S_IFCHR);
235
236    if (sehandle) {
237        if (selabel_lookup_best_match(sehandle, &secontext, path, links, mode)) {
238            PLOG(ERROR) << "Device '" << path << "' not created; cannot find SELinux label";
239            return;
240        }
241        setfscreatecon(secontext);
242    }
243
244    dev = makedev(major, minor);
245    /* Temporarily change egid to avoid race condition setting the gid of the
246     * device node. Unforunately changing the euid would prevent creation of
247     * some device nodes, so the uid has to be set with chown() and is still
248     * racy. Fixing the gid race at least fixed the issue with system_server
249     * opening dynamic input devices under the AID_INPUT gid. */
250    if (setegid(gid)) {
251        PLOG(ERROR) << "setegid(" << gid << ") for " << path << " device failed";
252        goto out;
253    }
254    /* If the node already exists update its SELinux label to handle cases when
255     * it was created with the wrong context during coldboot procedure. */
256    if (mknod(path, mode, dev) && (errno == EEXIST) && secontext) {
257
258        char* fcon = nullptr;
259        int rc = lgetfilecon(path, &fcon);
260        if (rc < 0) {
261            PLOG(ERROR) << "Cannot get SELinux label on '" << path << "' device";
262            goto out;
263        }
264
265        bool different = strcmp(fcon, secontext) != 0;
266        freecon(fcon);
267
268        if (different && lsetfilecon(path, secontext)) {
269            PLOG(ERROR) << "Cannot set '" << secontext << "' SELinux label on '" << path << "' device";
270        }
271    }
272
273out:
274    chown(path, uid, -1);
275    if (setegid(AID_ROOT)) {
276        PLOG(FATAL) << "setegid(AID_ROOT) failed";
277    }
278
279    if (secontext) {
280        freecon(secontext);
281        setfscreatecon(NULL);
282    }
283}
284
285void add_platform_device(const char* path) {
286    int path_len = strlen(path);
287    struct platform_node *bus;
288    const char *name = path;
289
290    if (!strncmp(path, "/devices/", 9)) {
291        name += 9;
292        if (!strncmp(name, "platform/", 9))
293            name += 9;
294    }
295
296    LOG(VERBOSE) << "adding platform device " << name << " (" << path << ")";
297
298    bus = (platform_node*) calloc(1, sizeof(struct platform_node));
299    bus->path = strdup(path);
300    bus->path_len = path_len;
301    bus->name = bus->path + (name - path);
302    list_add_tail(&platform_names, &bus->list);
303}
304
305/*
306 * given a path that may start with a platform device, find the length of the
307 * platform device prefix.  If it doesn't start with a platform device, return
308 * 0.
309 */
310static struct platform_node *find_platform_device(const char *path)
311{
312    int path_len = strlen(path);
313    struct listnode *node;
314    struct platform_node *bus;
315
316    list_for_each_reverse(node, &platform_names) {
317        bus = node_to_item(node, struct platform_node, list);
318        if ((bus->path_len < path_len) &&
319                (path[bus->path_len] == '/') &&
320                !strncmp(path, bus->path, bus->path_len))
321            return bus;
322    }
323
324    return NULL;
325}
326
327void remove_platform_device(const char* path) {
328    struct listnode *node;
329    struct platform_node *bus;
330
331    list_for_each_reverse(node, &platform_names) {
332        bus = node_to_item(node, struct platform_node, list);
333        if (!strcmp(path, bus->path)) {
334            LOG(INFO) << "removing platform device " << bus->name;
335            free(bus->path);
336            list_remove(node);
337            free(bus);
338            return;
339        }
340    }
341}
342
343static void destroy_platform_devices() {
344    struct listnode* node;
345    struct listnode* n;
346    struct platform_node* bus;
347
348    list_for_each_safe(node, n, &platform_names) {
349        list_remove(node);
350        bus = node_to_item(node, struct platform_node, list);
351        free(bus->path);
352        free(bus);
353    }
354}
355
356/* Given a path that may start with a PCI device, populate the supplied buffer
357 * with the PCI domain/bus number and the peripheral ID and return 0.
358 * If it doesn't start with a PCI device, or there is some error, return -1 */
359static int find_pci_device_prefix(const char *path, char *buf, ssize_t buf_sz)
360{
361    const char *start, *end;
362
363    if (strncmp(path, "/devices/pci", 12))
364        return -1;
365
366    /* Beginning of the prefix is the initial "pci" after "/devices/" */
367    start = path + 9;
368
369    /* End of the prefix is two path '/' later, capturing the domain/bus number
370     * and the peripheral ID. Example: pci0000:00/0000:00:1f.2 */
371    end = strchr(start, '/');
372    if (!end)
373        return -1;
374    end = strchr(end + 1, '/');
375    if (!end)
376        return -1;
377
378    /* Make sure we have enough room for the string plus null terminator */
379    if (end - start + 1 > buf_sz)
380        return -1;
381
382    strncpy(buf, start, end - start);
383    buf[end - start] = '\0';
384    return 0;
385}
386
387/* Given a path that may start with a virtual block device, populate
388 * the supplied buffer with the virtual block device ID and return 0.
389 * If it doesn't start with a virtual block device, or there is some
390 * error, return -1 */
391static int find_vbd_device_prefix(const char *path, char *buf, ssize_t buf_sz)
392{
393    const char *start, *end;
394
395    /* Beginning of the prefix is the initial "vbd-" after "/devices/" */
396    if (strncmp(path, "/devices/vbd-", 13))
397        return -1;
398
399    /* End of the prefix is one path '/' later, capturing the
400       virtual block device ID. Example: 768 */
401    start = path + 13;
402    end = strchr(start, '/');
403    if (!end)
404        return -1;
405
406    /* Make sure we have enough room for the string plus null terminator */
407    if (end - start + 1 > buf_sz)
408        return -1;
409
410    strncpy(buf, start, end - start);
411    buf[end - start] = '\0';
412    return 0;
413}
414
415static void parse_event(const char *msg, struct uevent *uevent)
416{
417    uevent->action = "";
418    uevent->path = "";
419    uevent->subsystem = "";
420    uevent->firmware = "";
421    uevent->major = -1;
422    uevent->minor = -1;
423    uevent->partition_name = NULL;
424    uevent->partition_num = -1;
425    uevent->device_name = NULL;
426
427        /* currently ignoring SEQNUM */
428    while(*msg) {
429        if(!strncmp(msg, "ACTION=", 7)) {
430            msg += 7;
431            uevent->action = msg;
432        } else if(!strncmp(msg, "DEVPATH=", 8)) {
433            msg += 8;
434            uevent->path = msg;
435        } else if(!strncmp(msg, "SUBSYSTEM=", 10)) {
436            msg += 10;
437            uevent->subsystem = msg;
438        } else if(!strncmp(msg, "FIRMWARE=", 9)) {
439            msg += 9;
440            uevent->firmware = msg;
441        } else if(!strncmp(msg, "MAJOR=", 6)) {
442            msg += 6;
443            uevent->major = atoi(msg);
444        } else if(!strncmp(msg, "MINOR=", 6)) {
445            msg += 6;
446            uevent->minor = atoi(msg);
447        } else if(!strncmp(msg, "PARTN=", 6)) {
448            msg += 6;
449            uevent->partition_num = atoi(msg);
450        } else if(!strncmp(msg, "PARTNAME=", 9)) {
451            msg += 9;
452            uevent->partition_name = msg;
453        } else if(!strncmp(msg, "DEVNAME=", 8)) {
454            msg += 8;
455            uevent->device_name = msg;
456        }
457
458        /* advance to after the next \0 */
459        while(*msg++)
460            ;
461    }
462
463    if (LOG_UEVENTS) {
464        LOG(INFO) << android::base::StringPrintf("event { '%s', '%s', '%s', '%s', %d, %d }",
465                                                 uevent->action, uevent->path, uevent->subsystem,
466                                                 uevent->firmware, uevent->major, uevent->minor);
467    }
468}
469
470char** get_character_device_symlinks(struct uevent* uevent) {
471    const char *parent;
472    const char *slash;
473    char **links;
474    int link_num = 0;
475    int width;
476    struct platform_node *pdev;
477
478    pdev = find_platform_device(uevent->path);
479    if (!pdev)
480        return NULL;
481
482    links = (char**) malloc(sizeof(char *) * 2);
483    if (!links)
484        return NULL;
485    memset(links, 0, sizeof(char *) * 2);
486
487    /* skip "/devices/platform/<driver>" */
488    parent = strchr(uevent->path + pdev->path_len, '/');
489    if (!parent)
490        goto err;
491
492    if (!strncmp(parent, "/usb", 4)) {
493        /* skip root hub name and device. use device interface */
494        while (*++parent && *parent != '/');
495        if (*parent)
496            while (*++parent && *parent != '/');
497        if (!*parent)
498            goto err;
499        slash = strchr(++parent, '/');
500        if (!slash)
501            goto err;
502        width = slash - parent;
503        if (width <= 0)
504            goto err;
505
506        if (asprintf(&links[link_num], "/dev/usb/%s%.*s", uevent->subsystem, width, parent) > 0)
507            link_num++;
508        else
509            links[link_num] = NULL;
510        mkdir("/dev/usb", 0755);
511    }
512    else {
513        goto err;
514    }
515
516    return links;
517err:
518    free(links);
519    return NULL;
520}
521
522// replaces any unacceptable characters with '_', the
523// length of the resulting string is equal to the input string
524void sanitize_partition_name(char* s) {
525    const char* accept =
526        "abcdefghijklmnopqrstuvwxyz"
527        "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
528        "0123456789"
529        "_-.";
530
531    if (!s) return;
532
533    while (*s) {
534        s += strspn(s, accept);
535        if (*s) *s++ = '_';
536    }
537}
538
539char** get_block_device_symlinks(struct uevent* uevent) {
540    const char *device;
541    struct platform_node *pdev;
542    const char *slash;
543    const char *type;
544    char buf[256];
545    char link_path[256];
546    int link_num = 0;
547    char *p;
548
549    pdev = find_platform_device(uevent->path);
550    if (pdev) {
551        device = pdev->name;
552        type = "platform";
553    } else if (!find_pci_device_prefix(uevent->path, buf, sizeof(buf))) {
554        device = buf;
555        type = "pci";
556    } else if (!find_vbd_device_prefix(uevent->path, buf, sizeof(buf))) {
557        device = buf;
558        type = "vbd";
559    } else {
560        return NULL;
561    }
562
563    char **links = (char**) malloc(sizeof(char *) * 4);
564    if (!links)
565        return NULL;
566    memset(links, 0, sizeof(char *) * 4);
567
568    LOG(VERBOSE) << "found " << type << " device " << device;
569
570    snprintf(link_path, sizeof(link_path), "/dev/block/%s/%s", type, device);
571
572    if (uevent->partition_name) {
573        p = strdup(uevent->partition_name);
574        sanitize_partition_name(p);
575        if (strcmp(uevent->partition_name, p)) {
576            LOG(VERBOSE) << "Linking partition '" << uevent->partition_name << "' as '" << p << "'";
577        }
578        if (asprintf(&links[link_num], "%s/by-name/%s", link_path, p) > 0)
579            link_num++;
580        else
581            links[link_num] = NULL;
582        free(p);
583    }
584
585    if (uevent->partition_num >= 0) {
586        if (asprintf(&links[link_num], "%s/by-num/p%d", link_path, uevent->partition_num) > 0)
587            link_num++;
588        else
589            links[link_num] = NULL;
590    }
591
592    slash = strrchr(uevent->path, '/');
593    if (asprintf(&links[link_num], "%s/%s", link_path, slash + 1) > 0)
594        link_num++;
595    else
596        links[link_num] = NULL;
597
598    return links;
599}
600
601static void make_link_init(const char* oldpath, const char* newpath) {
602  const char* slash = strrchr(newpath, '/');
603  if (!slash) return;
604
605  if (mkdir_recursive(dirname(newpath), 0755)) {
606    PLOG(ERROR) << "Failed to create directory " << dirname(newpath);
607  }
608
609  if (symlink(oldpath, newpath) && errno != EEXIST) {
610    PLOG(ERROR) << "Failed to symlink " << oldpath << " to " << newpath;
611  }
612}
613
614static void remove_link(const char* oldpath, const char* newpath) {
615  std::string path;
616  if (android::base::Readlink(newpath, &path) && path == oldpath) unlink(newpath);
617}
618
619static void handle_device(const char *action, const char *devpath,
620        const char *path, int block, int major, int minor, char **links)
621{
622    if(!strcmp(action, "add")) {
623        make_device(devpath, path, block, major, minor, (const char **)links);
624        if (links) {
625            for (int i = 0; links[i]; i++) {
626                make_link_init(devpath, links[i]);
627            }
628        }
629    }
630
631    if(!strcmp(action, "remove")) {
632        if (links) {
633            for (int i = 0; links[i]; i++) {
634                remove_link(devpath, links[i]);
635            }
636        }
637        unlink(devpath);
638    }
639
640    if (links) {
641        for (int i = 0; links[i]; i++) {
642            free(links[i]);
643        }
644        free(links);
645    }
646}
647
648static void handle_platform_device_event(struct uevent *uevent)
649{
650    const char *path = uevent->path;
651
652    if (!strcmp(uevent->action, "add"))
653        add_platform_device(path);
654    else if (!strcmp(uevent->action, "remove"))
655        remove_platform_device(path);
656}
657
658static const char *parse_device_name(struct uevent *uevent, unsigned int len)
659{
660    const char *name;
661
662    /* if it's not a /dev device, nothing else to do */
663    if((uevent->major < 0) || (uevent->minor < 0))
664        return NULL;
665
666    /* do we have a name? */
667    name = strrchr(uevent->path, '/');
668    if(!name)
669        return NULL;
670    name++;
671
672    /* too-long names would overrun our buffer */
673    if(strlen(name) > len) {
674        LOG(ERROR) << "DEVPATH=" << name << " exceeds " << len << "-character limit on filename; ignoring event";
675        return NULL;
676    }
677
678    return name;
679}
680
681#define DEVPATH_LEN 96
682#define MAX_DEV_NAME 64
683
684static void handle_block_device_event(struct uevent *uevent)
685{
686    const char *base = "/dev/block/";
687    const char *name;
688    char devpath[DEVPATH_LEN];
689    char **links = NULL;
690
691    name = parse_device_name(uevent, MAX_DEV_NAME);
692    if (!name)
693        return;
694
695    snprintf(devpath, sizeof(devpath), "%s%s", base, name);
696    make_dir(base, 0755);
697
698    if (!strncmp(uevent->path, "/devices/", 9))
699        links = get_block_device_symlinks(uevent);
700
701    handle_device(uevent->action, devpath, uevent->path, 1,
702            uevent->major, uevent->minor, links);
703}
704
705static bool assemble_devpath(char *devpath, const char *dirname,
706        const char *devname)
707{
708    int s = snprintf(devpath, DEVPATH_LEN, "%s/%s", dirname, devname);
709    if (s < 0) {
710        PLOG(ERROR) << "failed to assemble device path; ignoring event";
711        return false;
712    } else if (s >= DEVPATH_LEN) {
713        LOG(ERROR) << dirname << "/" << devname
714                   << " exceeds " << DEVPATH_LEN << "-character limit on path; ignoring event";
715        return false;
716    }
717    return true;
718}
719
720static void mkdir_recursive_for_devpath(const char *devpath)
721{
722    char dir[DEVPATH_LEN];
723    char *slash;
724
725    strcpy(dir, devpath);
726    slash = strrchr(dir, '/');
727    *slash = '\0';
728    mkdir_recursive(dir, 0755);
729}
730
731static void handle_generic_device_event(struct uevent *uevent)
732{
733    const char *base;
734    const char *name;
735    char devpath[DEVPATH_LEN] = {0};
736    char **links = NULL;
737
738    name = parse_device_name(uevent, MAX_DEV_NAME);
739    if (!name)
740        return;
741
742    struct ueventd_subsystem *subsystem =
743            ueventd_subsystem_find_by_name(uevent->subsystem);
744
745    if (subsystem) {
746        const char *devname;
747
748        switch (subsystem->devname_src) {
749        case DEVNAME_UEVENT_DEVNAME:
750            devname = uevent->device_name;
751            break;
752
753        case DEVNAME_UEVENT_DEVPATH:
754            devname = name;
755            break;
756
757        default:
758            LOG(ERROR) << uevent->subsystem << " subsystem's devpath option is not set; ignoring event";
759            return;
760        }
761
762        if (!assemble_devpath(devpath, subsystem->dirname, devname))
763            return;
764        mkdir_recursive_for_devpath(devpath);
765    } else if (!strncmp(uevent->subsystem, "usb", 3)) {
766         if (!strcmp(uevent->subsystem, "usb")) {
767            if (uevent->device_name) {
768                if (!assemble_devpath(devpath, "/dev", uevent->device_name))
769                    return;
770                mkdir_recursive_for_devpath(devpath);
771             }
772             else {
773                 /* This imitates the file system that would be created
774                  * if we were using devfs instead.
775                  * Minors are broken up into groups of 128, starting at "001"
776                  */
777                 int bus_id = uevent->minor / 128 + 1;
778                 int device_id = uevent->minor % 128 + 1;
779                 /* build directories */
780                 make_dir("/dev/bus", 0755);
781                 make_dir("/dev/bus/usb", 0755);
782                 snprintf(devpath, sizeof(devpath), "/dev/bus/usb/%03d", bus_id);
783                 make_dir(devpath, 0755);
784                 snprintf(devpath, sizeof(devpath), "/dev/bus/usb/%03d/%03d", bus_id, device_id);
785             }
786         } else {
787             /* ignore other USB events */
788             return;
789         }
790     } else if (!strncmp(uevent->subsystem, "graphics", 8)) {
791         base = "/dev/graphics/";
792         make_dir(base, 0755);
793     } else if (!strncmp(uevent->subsystem, "drm", 3)) {
794         base = "/dev/dri/";
795         make_dir(base, 0755);
796     } else if (!strncmp(uevent->subsystem, "oncrpc", 6)) {
797         base = "/dev/oncrpc/";
798         make_dir(base, 0755);
799     } else if (!strncmp(uevent->subsystem, "adsp", 4)) {
800         base = "/dev/adsp/";
801         make_dir(base, 0755);
802     } else if (!strncmp(uevent->subsystem, "msm_camera", 10)) {
803         base = "/dev/msm_camera/";
804         make_dir(base, 0755);
805     } else if(!strncmp(uevent->subsystem, "input", 5)) {
806         base = "/dev/input/";
807         make_dir(base, 0755);
808     } else if(!strncmp(uevent->subsystem, "mtd", 3)) {
809         base = "/dev/mtd/";
810         make_dir(base, 0755);
811     } else if(!strncmp(uevent->subsystem, "sound", 5)) {
812         base = "/dev/snd/";
813         make_dir(base, 0755);
814     } else
815         base = "/dev/";
816     links = get_character_device_symlinks(uevent);
817
818     if (!devpath[0])
819         snprintf(devpath, sizeof(devpath), "%s%s", base, name);
820
821     handle_device(uevent->action, devpath, uevent->path, 0,
822             uevent->major, uevent->minor, links);
823}
824
825static void handle_device_event(struct uevent *uevent)
826{
827    if (!strcmp(uevent->action,"add") || !strcmp(uevent->action, "change") || !strcmp(uevent->action, "online"))
828        fixup_sys_perms(uevent->path, uevent->subsystem);
829
830    if (!strncmp(uevent->subsystem, "block", 5)) {
831        handle_block_device_event(uevent);
832    } else if (!strncmp(uevent->subsystem, "platform", 8)) {
833        handle_platform_device_event(uevent);
834    } else {
835        handle_generic_device_event(uevent);
836    }
837}
838
839static void load_firmware(uevent* uevent, const std::string& root,
840                          int fw_fd, size_t fw_size,
841                          int loading_fd, int data_fd) {
842    // Start transfer.
843    android::base::WriteFully(loading_fd, "1", 1);
844
845    // Copy the firmware.
846    int rc = sendfile(data_fd, fw_fd, nullptr, fw_size);
847    if (rc == -1) {
848        PLOG(ERROR) << "firmware: sendfile failed { '" << root << "', '" << uevent->firmware << "' }";
849    }
850
851    // Tell the firmware whether to abort or commit.
852    const char* response = (rc != -1) ? "0" : "-1";
853    android::base::WriteFully(loading_fd, response, strlen(response));
854}
855
856static int is_booting() {
857    return access("/dev/.booting", F_OK) == 0;
858}
859
860static void process_firmware_event(uevent* uevent) {
861    int booting = is_booting();
862
863    LOG(INFO) << "firmware: loading '" << uevent->firmware << "' for '" << uevent->path << "'";
864
865    std::string root = android::base::StringPrintf("/sys%s", uevent->path);
866    std::string loading = root + "/loading";
867    std::string data = root + "/data";
868
869    android::base::unique_fd loading_fd(open(loading.c_str(), O_WRONLY|O_CLOEXEC));
870    if (loading_fd == -1) {
871        PLOG(ERROR) << "couldn't open firmware loading fd for " << uevent->firmware;
872        return;
873    }
874
875    android::base::unique_fd data_fd(open(data.c_str(), O_WRONLY|O_CLOEXEC));
876    if (data_fd == -1) {
877        PLOG(ERROR) << "couldn't open firmware data fd for " << uevent->firmware;
878        return;
879    }
880
881try_loading_again:
882    for (size_t i = 0; i < arraysize(firmware_dirs); i++) {
883        std::string file = android::base::StringPrintf("%s/%s", firmware_dirs[i], uevent->firmware);
884        android::base::unique_fd fw_fd(open(file.c_str(), O_RDONLY|O_CLOEXEC));
885        struct stat sb;
886        if (fw_fd != -1 && fstat(fw_fd, &sb) != -1) {
887            load_firmware(uevent, root, fw_fd, sb.st_size, loading_fd, data_fd);
888            return;
889        }
890    }
891
892    if (booting) {
893        // If we're not fully booted, we may be missing
894        // filesystems needed for firmware, wait and retry.
895        std::this_thread::sleep_for(100ms);
896        booting = is_booting();
897        goto try_loading_again;
898    }
899
900    LOG(ERROR) << "firmware: could not find firmware for " << uevent->firmware;
901
902    // Write "-1" as our response to the kernel's firmware request, since we have nothing for it.
903    write(loading_fd, "-1", 2);
904}
905
906static void handle_firmware_event(uevent* uevent) {
907    if (strcmp(uevent->subsystem, "firmware")) return;
908    if (strcmp(uevent->action, "add")) return;
909
910    // Loading the firmware in a child means we can do that in parallel...
911    // (We ignore SIGCHLD rather than wait for our children.)
912    pid_t pid = fork();
913    if (pid == 0) {
914        Timer t;
915        process_firmware_event(uevent);
916        LOG(INFO) << "loading " << uevent->path << " took " << t;
917        _exit(EXIT_SUCCESS);
918    } else if (pid == -1) {
919        PLOG(ERROR) << "could not fork to process firmware event for " << uevent->firmware;
920    }
921}
922
923static bool inline should_stop_coldboot(coldboot_action_t act)
924{
925    return (act == COLDBOOT_STOP || act == COLDBOOT_FINISH);
926}
927
928#define UEVENT_MSG_LEN  2048
929
930static inline coldboot_action_t handle_device_fd_with(
931        std::function<coldboot_action_t(uevent* uevent)> handle_uevent)
932{
933    char msg[UEVENT_MSG_LEN+2];
934    int n;
935    while ((n = uevent_kernel_multicast_recv(device_fd, msg, UEVENT_MSG_LEN)) > 0) {
936        if(n >= UEVENT_MSG_LEN)   /* overflow -- discard */
937            continue;
938
939        msg[n] = '\0';
940        msg[n+1] = '\0';
941
942        struct uevent uevent;
943        parse_event(msg, &uevent);
944        coldboot_action_t act = handle_uevent(&uevent);
945        if (should_stop_coldboot(act))
946            return act;
947    }
948
949    return COLDBOOT_CONTINUE;
950}
951
952coldboot_action_t handle_device_fd(coldboot_callback fn)
953{
954    coldboot_action_t ret = handle_device_fd_with(
955        [&](uevent* uevent) -> coldboot_action_t {
956            if (selinux_status_updated() > 0) {
957                struct selabel_handle *sehandle2;
958                sehandle2 = selinux_android_file_context_handle();
959                if (sehandle2) {
960                    selabel_close(sehandle);
961                    sehandle = sehandle2;
962                }
963            }
964
965            // default is to always create the devices
966            coldboot_action_t act = COLDBOOT_CREATE;
967            if (fn) {
968                act = fn(uevent);
969            }
970
971            if (act == COLDBOOT_CREATE || act == COLDBOOT_STOP) {
972                handle_device_event(uevent);
973                handle_firmware_event(uevent);
974            }
975
976            return act;
977        });
978
979    return ret;
980}
981
982/* Coldboot walks parts of the /sys tree and pokes the uevent files
983** to cause the kernel to regenerate device add events that happened
984** before init's device manager was started
985**
986** We drain any pending events from the netlink socket every time
987** we poke another uevent file to make sure we don't overrun the
988** socket's buffer.
989*/
990
991static coldboot_action_t do_coldboot(DIR *d, coldboot_callback fn)
992{
993    struct dirent *de;
994    int dfd, fd;
995    coldboot_action_t act = COLDBOOT_CONTINUE;
996
997    dfd = dirfd(d);
998
999    fd = openat(dfd, "uevent", O_WRONLY);
1000    if (fd >= 0) {
1001        write(fd, "add\n", 4);
1002        close(fd);
1003        act = handle_device_fd(fn);
1004        if (should_stop_coldboot(act))
1005            return act;
1006    }
1007
1008    while (!should_stop_coldboot(act) && (de = readdir(d))) {
1009        DIR *d2;
1010
1011        if(de->d_type != DT_DIR || de->d_name[0] == '.')
1012            continue;
1013
1014        fd = openat(dfd, de->d_name, O_RDONLY | O_DIRECTORY);
1015        if(fd < 0)
1016            continue;
1017
1018        d2 = fdopendir(fd);
1019        if(d2 == 0)
1020            close(fd);
1021        else {
1022            act = do_coldboot(d2, fn);
1023            closedir(d2);
1024        }
1025    }
1026
1027    // default is always to continue looking for uevents
1028    return act;
1029}
1030
1031static coldboot_action_t coldboot(const char *path, coldboot_callback fn)
1032{
1033    std::unique_ptr<DIR, decltype(&closedir)> d(opendir(path), closedir);
1034    if (d) {
1035        return do_coldboot(d.get(), fn);
1036    }
1037
1038    return COLDBOOT_CONTINUE;
1039}
1040
1041void device_init(const char* path, coldboot_callback fn) {
1042    if (!sehandle) {
1043        sehandle = selinux_android_file_context_handle();
1044    }
1045    // open uevent socket and selinux status only if it hasn't been
1046    // done before
1047    if (device_fd == -1) {
1048        /* is 256K enough? udev uses 16MB! */
1049        device_fd.reset(uevent_open_socket(256 * 1024, true));
1050        if (device_fd == -1) {
1051            return;
1052        }
1053        fcntl(device_fd, F_SETFL, O_NONBLOCK);
1054        selinux_status_open(true);
1055    }
1056
1057    if (access(COLDBOOT_DONE, F_OK) == 0) {
1058        LOG(VERBOSE) << "Skipping coldboot, already done!";
1059        return;
1060    }
1061
1062    Timer t;
1063    coldboot_action_t act;
1064    if (!path) {
1065        act = coldboot("/sys/class", fn);
1066        if (!should_stop_coldboot(act)) {
1067            act = coldboot("/sys/block", fn);
1068            if (!should_stop_coldboot(act)) {
1069                act = coldboot("/sys/devices", fn);
1070            }
1071        }
1072    } else {
1073        act = coldboot(path, fn);
1074    }
1075
1076    // If we have a callback, then do as it says. If no, then the default is
1077    // to always create COLDBOOT_DONE file.
1078    if (!fn || (act == COLDBOOT_FINISH)) {
1079        close(open(COLDBOOT_DONE, O_WRONLY|O_CREAT|O_CLOEXEC, 0000));
1080    }
1081
1082    LOG(INFO) << "Coldboot took " << t;
1083}
1084
1085void device_close() {
1086    destroy_platform_devices();
1087    device_fd.reset();
1088    selinux_status_close();
1089}
1090
1091int get_device_fd() {
1092    return device_fd;
1093}
1094