devices.cpp revision a8d8434c42b27f0186be7ecd78c2acc9d459b068 
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 <stddef.h>
23#include <stdio.h>
24#include <stdlib.h>
25#include <string.h>
26#include <sys/sendfile.h>
27#include <sys/socket.h>
28#include <sys/stat.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 <linux/netlink.h>
36
37#include <memory>
38#include <thread>
39
40#include <selinux/selinux.h>
41#include <selinux/label.h>
42#include <selinux/android.h>
43#include <selinux/avc.h>
44
45#include <private/android_filesystem_config.h>
46
47#include <android-base/file.h>
48#include <android-base/stringprintf.h>
49#include <android-base/unique_fd.h>
50#include <cutils/list.h>
51#include <cutils/uevent.h>
52
53#include "devices.h"
54#include "ueventd_parser.h"
55#include "util.h"
56#include "log.h"
57
58#define SYSFS_PREFIX    "/sys"
59static const char *firmware_dirs[] = { "/etc/firmware",
60                                       "/vendor/firmware",
61                                       "/firmware/image" };
62
63extern struct selabel_handle *sehandle;
64
65static int device_fd = -1;
66
67struct uevent {
68    const char *action;
69    const char *path;
70    const char *subsystem;
71    const char *firmware;
72    const char *partition_name;
73    const char *device_name;
74    int partition_num;
75    int major;
76    int minor;
77};
78
79struct perms_ {
80    char *name;
81    char *attr;
82    mode_t perm;
83    unsigned int uid;
84    unsigned int gid;
85    unsigned short prefix;
86    unsigned short wildcard;
87};
88
89struct perm_node {
90    struct perms_ dp;
91    struct listnode plist;
92};
93
94struct platform_node {
95    char *name;
96    char *path;
97    int path_len;
98    struct listnode list;
99};
100
101static list_declare(sys_perms);
102static list_declare(dev_perms);
103static list_declare(platform_names);
104
105int add_dev_perms(const char *name, const char *attr,
106                  mode_t perm, unsigned int uid, unsigned int gid,
107                  unsigned short prefix,
108                  unsigned short wildcard) {
109    struct perm_node *node = (perm_node*) calloc(1, sizeof(*node));
110    if (!node)
111        return -ENOMEM;
112
113    node->dp.name = strdup(name);
114    if (!node->dp.name) {
115        free(node);
116        return -ENOMEM;
117    }
118
119    if (attr) {
120        node->dp.attr = strdup(attr);
121        if (!node->dp.attr) {
122            free(node->dp.name);
123            free(node);
124            return -ENOMEM;
125        }
126    }
127
128    node->dp.perm = perm;
129    node->dp.uid = uid;
130    node->dp.gid = gid;
131    node->dp.prefix = prefix;
132    node->dp.wildcard = wildcard;
133
134    if (attr)
135        list_add_tail(&sys_perms, &node->plist);
136    else
137        list_add_tail(&dev_perms, &node->plist);
138
139    return 0;
140}
141
142static bool perm_path_matches(const char *path, struct perms_ *dp)
143{
144    if (dp->prefix) {
145        if (strncmp(path, dp->name, strlen(dp->name)) == 0)
146            return true;
147    } else if (dp->wildcard) {
148        if (fnmatch(dp->name, path, FNM_PATHNAME) == 0)
149            return true;
150    } else {
151        if (strcmp(path, dp->name) == 0)
152            return true;
153    }
154
155    return false;
156}
157
158static bool match_subsystem(perms_* dp, const char* pattern,
159                            const char* path, const char* subsystem) {
160    if (!pattern || !subsystem || strstr(dp->name, subsystem) == NULL) {
161        return false;
162    }
163
164    std::string subsys_path = android::base::StringPrintf(pattern, subsystem, basename(path));
165    return perm_path_matches(subsys_path.c_str(), dp);
166}
167
168static void fixup_sys_perms(const char* upath, const char* subsystem) {
169    // upaths omit the "/sys" that paths in this list
170    // contain, so we prepend it...
171    std::string path = std::string(SYSFS_PREFIX) + upath;
172
173    listnode* node;
174    list_for_each(node, &sys_perms) {
175        perms_* dp = &(node_to_item(node, perm_node, plist))->dp;
176        if (match_subsystem(dp, SYSFS_PREFIX "/class/%s/%s", path.c_str(), subsystem)) {
177            ; // matched
178        } else if (match_subsystem(dp, SYSFS_PREFIX "/bus/%s/devices/%s", path.c_str(), subsystem)) {
179            ; // matched
180        } else if (!perm_path_matches(path.c_str(), dp)) {
181            continue;
182        }
183
184        std::string attr_file = path + "/" + dp->attr;
185        LOG(INFO) << "fixup " << attr_file
186                  << " " << dp->uid << " " << dp->gid << " " << std::oct << dp->perm;
187        chown(attr_file.c_str(), dp->uid, dp->gid);
188        chmod(attr_file.c_str(), dp->perm);
189    }
190
191    if (access(path.c_str(), F_OK) == 0) {
192        LOG(VERBOSE) << "restorecon_recursive: " << path;
193        restorecon(path.c_str(), SELINUX_ANDROID_RESTORECON_RECURSE);
194    }
195}
196
197static mode_t get_device_perm(const char *path, const char **links,
198                unsigned *uid, unsigned *gid)
199{
200    struct listnode *node;
201    struct perm_node *perm_node;
202    struct perms_ *dp;
203
204    /* search the perms list in reverse so that ueventd.$hardware can
205     * override ueventd.rc
206     */
207    list_for_each_reverse(node, &dev_perms) {
208        bool match = false;
209
210        perm_node = node_to_item(node, struct perm_node, plist);
211        dp = &perm_node->dp;
212
213        if (perm_path_matches(path, dp)) {
214            match = true;
215        } else {
216            if (links) {
217                int i;
218                for (i = 0; links[i]; i++) {
219                    if (perm_path_matches(links[i], dp)) {
220                        match = true;
221                        break;
222                    }
223                }
224            }
225        }
226
227        if (match) {
228            *uid = dp->uid;
229            *gid = dp->gid;
230            return dp->perm;
231        }
232    }
233    /* Default if nothing found. */
234    *uid = 0;
235    *gid = 0;
236    return 0600;
237}
238
239static void make_device(const char *path,
240                        const char */*upath*/,
241                        int block, int major, int minor,
242                        const char **links)
243{
244    unsigned uid;
245    unsigned gid;
246    mode_t mode;
247    dev_t dev;
248    char *secontext = NULL;
249
250    mode = get_device_perm(path, links, &uid, &gid) | (block ? S_IFBLK : S_IFCHR);
251
252    if (selabel_lookup_best_match(sehandle, &secontext, path, links, mode)) {
253        PLOG(ERROR) << "Device '" << path << "' not created; cannot find SELinux label";
254        return;
255    }
256    setfscreatecon(secontext);
257
258    dev = makedev(major, minor);
259    /* Temporarily change egid to avoid race condition setting the gid of the
260     * device node. Unforunately changing the euid would prevent creation of
261     * some device nodes, so the uid has to be set with chown() and is still
262     * racy. Fixing the gid race at least fixed the issue with system_server
263     * opening dynamic input devices under the AID_INPUT gid. */
264    setegid(gid);
265    /* If the node already exists update its SELinux label to handle cases when
266     * it was created with the wrong context during coldboot procedure. */
267    if (mknod(path, mode, dev) && (errno == EEXIST)) {
268
269        char* fcon = nullptr;
270        int rc = lgetfilecon(path, &fcon);
271        if (rc < 0) {
272            PLOG(ERROR) << "Cannot get SELinux label on '" << path << "' device";
273            goto out;
274        }
275
276        bool different = strcmp(fcon, secontext) != 0;
277        freecon(fcon);
278
279        if (different && lsetfilecon(path, secontext)) {
280            PLOG(ERROR) << "Cannot set '" << secontext << "' SELinux label on '" << path << "' device";
281        }
282    }
283
284out:
285    chown(path, uid, -1);
286    setegid(AID_ROOT);
287
288    freecon(secontext);
289    setfscreatecon(NULL);
290}
291
292static void add_platform_device(const char *path)
293{
294    int path_len = strlen(path);
295    struct platform_node *bus;
296    const char *name = path;
297
298    if (!strncmp(path, "/devices/", 9)) {
299        name += 9;
300        if (!strncmp(name, "platform/", 9))
301            name += 9;
302    }
303
304    LOG(VERBOSE) << "adding platform device " << name << " (" << path << ")";
305
306    bus = (platform_node*) calloc(1, sizeof(struct platform_node));
307    bus->path = strdup(path);
308    bus->path_len = path_len;
309    bus->name = bus->path + (name - path);
310    list_add_tail(&platform_names, &bus->list);
311}
312
313/*
314 * given a path that may start with a platform device, find the length of the
315 * platform device prefix.  If it doesn't start with a platform device, return
316 * 0.
317 */
318static struct platform_node *find_platform_device(const char *path)
319{
320    int path_len = strlen(path);
321    struct listnode *node;
322    struct platform_node *bus;
323
324    list_for_each_reverse(node, &platform_names) {
325        bus = node_to_item(node, struct platform_node, list);
326        if ((bus->path_len < path_len) &&
327                (path[bus->path_len] == '/') &&
328                !strncmp(path, bus->path, bus->path_len))
329            return bus;
330    }
331
332    return NULL;
333}
334
335static void remove_platform_device(const char *path)
336{
337    struct listnode *node;
338    struct platform_node *bus;
339
340    list_for_each_reverse(node, &platform_names) {
341        bus = node_to_item(node, struct platform_node, list);
342        if (!strcmp(path, bus->path)) {
343            LOG(INFO) << "removing platform device " << bus->name;
344            free(bus->path);
345            list_remove(node);
346            free(bus);
347            return;
348        }
349    }
350}
351
352/* Given a path that may start with a PCI device, populate the supplied buffer
353 * with the PCI domain/bus number and the peripheral ID and return 0.
354 * If it doesn't start with a PCI device, or there is some error, return -1 */
355static int find_pci_device_prefix(const char *path, char *buf, ssize_t buf_sz)
356{
357    const char *start, *end;
358
359    if (strncmp(path, "/devices/pci", 12))
360        return -1;
361
362    /* Beginning of the prefix is the initial "pci" after "/devices/" */
363    start = path + 9;
364
365    /* End of the prefix is two path '/' later, capturing the domain/bus number
366     * and the peripheral ID. Example: pci0000:00/0000:00:1f.2 */
367    end = strchr(start, '/');
368    if (!end)
369        return -1;
370    end = strchr(end + 1, '/');
371    if (!end)
372        return -1;
373
374    /* Make sure we have enough room for the string plus null terminator */
375    if (end - start + 1 > buf_sz)
376        return -1;
377
378    strncpy(buf, start, end - start);
379    buf[end - start] = '\0';
380    return 0;
381}
382
383static void parse_event(const char *msg, struct uevent *uevent)
384{
385    uevent->action = "";
386    uevent->path = "";
387    uevent->subsystem = "";
388    uevent->firmware = "";
389    uevent->major = -1;
390    uevent->minor = -1;
391    uevent->partition_name = NULL;
392    uevent->partition_num = -1;
393    uevent->device_name = NULL;
394
395        /* currently ignoring SEQNUM */
396    while(*msg) {
397        if(!strncmp(msg, "ACTION=", 7)) {
398            msg += 7;
399            uevent->action = msg;
400        } else if(!strncmp(msg, "DEVPATH=", 8)) {
401            msg += 8;
402            uevent->path = msg;
403        } else if(!strncmp(msg, "SUBSYSTEM=", 10)) {
404            msg += 10;
405            uevent->subsystem = msg;
406        } else if(!strncmp(msg, "FIRMWARE=", 9)) {
407            msg += 9;
408            uevent->firmware = msg;
409        } else if(!strncmp(msg, "MAJOR=", 6)) {
410            msg += 6;
411            uevent->major = atoi(msg);
412        } else if(!strncmp(msg, "MINOR=", 6)) {
413            msg += 6;
414            uevent->minor = atoi(msg);
415        } else if(!strncmp(msg, "PARTN=", 6)) {
416            msg += 6;
417            uevent->partition_num = atoi(msg);
418        } else if(!strncmp(msg, "PARTNAME=", 9)) {
419            msg += 9;
420            uevent->partition_name = msg;
421        } else if(!strncmp(msg, "DEVNAME=", 8)) {
422            msg += 8;
423            uevent->device_name = msg;
424        }
425
426        /* advance to after the next \0 */
427        while(*msg++)
428            ;
429    }
430
431    if (LOG_UEVENTS) {
432        LOG(INFO) << android::base::StringPrintf("event { '%s', '%s', '%s', '%s', %d, %d }",
433                                                 uevent->action, uevent->path, uevent->subsystem,
434                                                 uevent->firmware, uevent->major, uevent->minor);
435    }
436}
437
438static char **get_character_device_symlinks(struct uevent *uevent)
439{
440    const char *parent;
441    const char *slash;
442    char **links;
443    int link_num = 0;
444    int width;
445    struct platform_node *pdev;
446
447    pdev = find_platform_device(uevent->path);
448    if (!pdev)
449        return NULL;
450
451    links = (char**) malloc(sizeof(char *) * 2);
452    if (!links)
453        return NULL;
454    memset(links, 0, sizeof(char *) * 2);
455
456    /* skip "/devices/platform/<driver>" */
457    parent = strchr(uevent->path + pdev->path_len, '/');
458    if (!parent)
459        goto err;
460
461    if (!strncmp(parent, "/usb", 4)) {
462        /* skip root hub name and device. use device interface */
463        while (*++parent && *parent != '/');
464        if (*parent)
465            while (*++parent && *parent != '/');
466        if (!*parent)
467            goto err;
468        slash = strchr(++parent, '/');
469        if (!slash)
470            goto err;
471        width = slash - parent;
472        if (width <= 0)
473            goto err;
474
475        if (asprintf(&links[link_num], "/dev/usb/%s%.*s", uevent->subsystem, width, parent) > 0)
476            link_num++;
477        else
478            links[link_num] = NULL;
479        mkdir("/dev/usb", 0755);
480    }
481    else {
482        goto err;
483    }
484
485    return links;
486err:
487    free(links);
488    return NULL;
489}
490
491static char **get_block_device_symlinks(struct uevent *uevent)
492{
493    const char *device;
494    struct platform_node *pdev;
495    const char *slash;
496    const char *type;
497    char buf[256];
498    char link_path[256];
499    int link_num = 0;
500    char *p;
501
502    pdev = find_platform_device(uevent->path);
503    if (pdev) {
504        device = pdev->name;
505        type = "platform";
506    } else if (!find_pci_device_prefix(uevent->path, buf, sizeof(buf))) {
507        device = buf;
508        type = "pci";
509    } else {
510        return NULL;
511    }
512
513    char **links = (char**) malloc(sizeof(char *) * 4);
514    if (!links)
515        return NULL;
516    memset(links, 0, sizeof(char *) * 4);
517
518    LOG(INFO) << "found " << type << " device " << device;
519
520    snprintf(link_path, sizeof(link_path), "/dev/block/%s/%s", type, device);
521
522    if (uevent->partition_name) {
523        p = strdup(uevent->partition_name);
524        sanitize(p);
525        if (strcmp(uevent->partition_name, p)) {
526            LOG(VERBOSE) << "Linking partition '" << uevent->partition_name << "' as '" << p << "'";
527        }
528        if (asprintf(&links[link_num], "%s/by-name/%s", link_path, p) > 0)
529            link_num++;
530        else
531            links[link_num] = NULL;
532        free(p);
533    }
534
535    if (uevent->partition_num >= 0) {
536        if (asprintf(&links[link_num], "%s/by-num/p%d", link_path, uevent->partition_num) > 0)
537            link_num++;
538        else
539            links[link_num] = NULL;
540    }
541
542    slash = strrchr(uevent->path, '/');
543    if (asprintf(&links[link_num], "%s/%s", link_path, slash + 1) > 0)
544        link_num++;
545    else
546        links[link_num] = NULL;
547
548    return links;
549}
550
551static void make_link_init(const char* oldpath, const char* newpath) {
552  const char* slash = strrchr(newpath, '/');
553  if (!slash) return;
554
555  if (mkdir_recursive(dirname(newpath), 0755)) {
556    PLOG(ERROR) << "Failed to create directory " << dirname(newpath);
557  }
558
559  if (symlink(oldpath, newpath) && errno != EEXIST) {
560    PLOG(ERROR) << "Failed to symlink " << oldpath << " to " << newpath;
561  }
562}
563
564static void remove_link(const char* oldpath, const char* newpath) {
565  std::string path;
566  if (android::base::Readlink(newpath, &path) && path == oldpath) unlink(newpath);
567}
568
569static void handle_device(const char *action, const char *devpath,
570        const char *path, int block, int major, int minor, char **links)
571{
572    if(!strcmp(action, "add")) {
573        make_device(devpath, path, block, major, minor, (const char **)links);
574        if (links) {
575            for (int i = 0; links[i]; i++) {
576                make_link_init(devpath, links[i]);
577            }
578        }
579    }
580
581    if(!strcmp(action, "remove")) {
582        if (links) {
583            for (int i = 0; links[i]; i++) {
584                remove_link(devpath, links[i]);
585            }
586        }
587        unlink(devpath);
588    }
589
590    if (links) {
591        for (int i = 0; links[i]; i++) {
592            free(links[i]);
593        }
594        free(links);
595    }
596}
597
598static void handle_platform_device_event(struct uevent *uevent)
599{
600    const char *path = uevent->path;
601
602    if (!strcmp(uevent->action, "add"))
603        add_platform_device(path);
604    else if (!strcmp(uevent->action, "remove"))
605        remove_platform_device(path);
606}
607
608static const char *parse_device_name(struct uevent *uevent, unsigned int len)
609{
610    const char *name;
611
612    /* if it's not a /dev device, nothing else to do */
613    if((uevent->major < 0) || (uevent->minor < 0))
614        return NULL;
615
616    /* do we have a name? */
617    name = strrchr(uevent->path, '/');
618    if(!name)
619        return NULL;
620    name++;
621
622    /* too-long names would overrun our buffer */
623    if(strlen(name) > len) {
624        LOG(ERROR) << "DEVPATH=" << name << " exceeds " << len << "-character limit on filename; ignoring event";
625        return NULL;
626    }
627
628    return name;
629}
630
631#define DEVPATH_LEN 96
632#define MAX_DEV_NAME 64
633
634static void handle_block_device_event(struct uevent *uevent)
635{
636    const char *base = "/dev/block/";
637    const char *name;
638    char devpath[DEVPATH_LEN];
639    char **links = NULL;
640
641    name = parse_device_name(uevent, MAX_DEV_NAME);
642    if (!name)
643        return;
644
645    snprintf(devpath, sizeof(devpath), "%s%s", base, name);
646    make_dir(base, 0755);
647
648    if (!strncmp(uevent->path, "/devices/", 9))
649        links = get_block_device_symlinks(uevent);
650
651    handle_device(uevent->action, devpath, uevent->path, 1,
652            uevent->major, uevent->minor, links);
653}
654
655static bool assemble_devpath(char *devpath, const char *dirname,
656        const char *devname)
657{
658    int s = snprintf(devpath, DEVPATH_LEN, "%s/%s", dirname, devname);
659    if (s < 0) {
660        PLOG(ERROR) << "failed to assemble device path; ignoring event";
661        return false;
662    } else if (s >= DEVPATH_LEN) {
663        LOG(ERROR) << dirname << "/" << devname
664                   << " exceeds " << DEVPATH_LEN << "-character limit on path; ignoring event";
665        return false;
666    }
667    return true;
668}
669
670static void mkdir_recursive_for_devpath(const char *devpath)
671{
672    char dir[DEVPATH_LEN];
673    char *slash;
674
675    strcpy(dir, devpath);
676    slash = strrchr(dir, '/');
677    *slash = '\0';
678    mkdir_recursive(dir, 0755);
679}
680
681static void handle_generic_device_event(struct uevent *uevent)
682{
683    const char *base;
684    const char *name;
685    char devpath[DEVPATH_LEN] = {0};
686    char **links = NULL;
687
688    name = parse_device_name(uevent, MAX_DEV_NAME);
689    if (!name)
690        return;
691
692    struct ueventd_subsystem *subsystem =
693            ueventd_subsystem_find_by_name(uevent->subsystem);
694
695    if (subsystem) {
696        const char *devname;
697
698        switch (subsystem->devname_src) {
699        case DEVNAME_UEVENT_DEVNAME:
700            devname = uevent->device_name;
701            break;
702
703        case DEVNAME_UEVENT_DEVPATH:
704            devname = name;
705            break;
706
707        default:
708            LOG(ERROR) << uevent->subsystem << " subsystem's devpath option is not set; ignoring event";
709            return;
710        }
711
712        if (!assemble_devpath(devpath, subsystem->dirname, devname))
713            return;
714        mkdir_recursive_for_devpath(devpath);
715    } else if (!strncmp(uevent->subsystem, "usb", 3)) {
716         if (!strcmp(uevent->subsystem, "usb")) {
717            if (uevent->device_name) {
718                if (!assemble_devpath(devpath, "/dev", uevent->device_name))
719                    return;
720                mkdir_recursive_for_devpath(devpath);
721             }
722             else {
723                 /* This imitates the file system that would be created
724                  * if we were using devfs instead.
725                  * Minors are broken up into groups of 128, starting at "001"
726                  */
727                 int bus_id = uevent->minor / 128 + 1;
728                 int device_id = uevent->minor % 128 + 1;
729                 /* build directories */
730                 make_dir("/dev/bus", 0755);
731                 make_dir("/dev/bus/usb", 0755);
732                 snprintf(devpath, sizeof(devpath), "/dev/bus/usb/%03d", bus_id);
733                 make_dir(devpath, 0755);
734                 snprintf(devpath, sizeof(devpath), "/dev/bus/usb/%03d/%03d", bus_id, device_id);
735             }
736         } else {
737             /* ignore other USB events */
738             return;
739         }
740     } else if (!strncmp(uevent->subsystem, "graphics", 8)) {
741         base = "/dev/graphics/";
742         make_dir(base, 0755);
743     } else if (!strncmp(uevent->subsystem, "drm", 3)) {
744         base = "/dev/dri/";
745         make_dir(base, 0755);
746     } else if (!strncmp(uevent->subsystem, "oncrpc", 6)) {
747         base = "/dev/oncrpc/";
748         make_dir(base, 0755);
749     } else if (!strncmp(uevent->subsystem, "adsp", 4)) {
750         base = "/dev/adsp/";
751         make_dir(base, 0755);
752     } else if (!strncmp(uevent->subsystem, "msm_camera", 10)) {
753         base = "/dev/msm_camera/";
754         make_dir(base, 0755);
755     } else if(!strncmp(uevent->subsystem, "input", 5)) {
756         base = "/dev/input/";
757         make_dir(base, 0755);
758     } else if(!strncmp(uevent->subsystem, "mtd", 3)) {
759         base = "/dev/mtd/";
760         make_dir(base, 0755);
761     } else if(!strncmp(uevent->subsystem, "sound", 5)) {
762         base = "/dev/snd/";
763         make_dir(base, 0755);
764     } else if(!strncmp(uevent->subsystem, "misc", 4) && !strncmp(name, "log_", 4)) {
765         LOG(INFO) << "kernel logger is deprecated";
766         base = "/dev/log/";
767         make_dir(base, 0755);
768         name += 4;
769     } else
770         base = "/dev/";
771     links = get_character_device_symlinks(uevent);
772
773     if (!devpath[0])
774         snprintf(devpath, sizeof(devpath), "%s%s", base, name);
775
776     handle_device(uevent->action, devpath, uevent->path, 0,
777             uevent->major, uevent->minor, links);
778}
779
780static void handle_device_event(struct uevent *uevent)
781{
782    if (!strcmp(uevent->action,"add") || !strcmp(uevent->action, "change") || !strcmp(uevent->action, "online"))
783        fixup_sys_perms(uevent->path, uevent->subsystem);
784
785    if (!strncmp(uevent->subsystem, "block", 5)) {
786        handle_block_device_event(uevent);
787    } else if (!strncmp(uevent->subsystem, "platform", 8)) {
788        handle_platform_device_event(uevent);
789    } else {
790        handle_generic_device_event(uevent);
791    }
792}
793
794static void load_firmware(uevent* uevent, const std::string& root,
795                          int fw_fd, size_t fw_size,
796                          int loading_fd, int data_fd) {
797    // Start transfer.
798    android::base::WriteFully(loading_fd, "1", 1);
799
800    // Copy the firmware.
801    int rc = sendfile(data_fd, fw_fd, nullptr, fw_size);
802    if (rc == -1) {
803        PLOG(ERROR) << "firmware: sendfile failed { '" << root << "', '" << uevent->firmware << "' }";
804    }
805
806    // Tell the firmware whether to abort or commit.
807    const char* response = (rc != -1) ? "0" : "-1";
808    android::base::WriteFully(loading_fd, response, strlen(response));
809}
810
811static int is_booting() {
812    return access("/dev/.booting", F_OK) == 0;
813}
814
815static void process_firmware_event(uevent* uevent) {
816    int booting = is_booting();
817
818    LOG(INFO) << "firmware: loading '" << uevent->firmware << "' for '" << uevent->path << "'";
819
820    std::string root = android::base::StringPrintf("/sys%s", uevent->path);
821    std::string loading = root + "/loading";
822    std::string data = root + "/data";
823
824    android::base::unique_fd loading_fd(open(loading.c_str(), O_WRONLY|O_CLOEXEC));
825    if (loading_fd == -1) {
826        PLOG(ERROR) << "couldn't open firmware loading fd for " << uevent->firmware;
827        return;
828    }
829
830    android::base::unique_fd data_fd(open(data.c_str(), O_WRONLY|O_CLOEXEC));
831    if (data_fd == -1) {
832        PLOG(ERROR) << "couldn't open firmware data fd for " << uevent->firmware;
833        return;
834    }
835
836try_loading_again:
837    for (size_t i = 0; i < arraysize(firmware_dirs); i++) {
838        std::string file = android::base::StringPrintf("%s/%s", firmware_dirs[i], uevent->firmware);
839        android::base::unique_fd fw_fd(open(file.c_str(), O_RDONLY|O_CLOEXEC));
840        struct stat sb;
841        if (fw_fd != -1 && fstat(fw_fd, &sb) != -1) {
842            load_firmware(uevent, root, fw_fd, sb.st_size, loading_fd, data_fd);
843            return;
844        }
845    }
846
847    if (booting) {
848        // If we're not fully booted, we may be missing
849        // filesystems needed for firmware, wait and retry.
850        std::this_thread::sleep_for(100ms);
851        booting = is_booting();
852        goto try_loading_again;
853    }
854
855    LOG(ERROR) << "firmware: could not find firmware for " << uevent->firmware;
856
857    // Write "-1" as our response to the kernel's firmware request, since we have nothing for it.
858    write(loading_fd, "-1", 2);
859}
860
861static void handle_firmware_event(uevent* uevent) {
862    if (strcmp(uevent->subsystem, "firmware")) return;
863    if (strcmp(uevent->action, "add")) return;
864
865    // Loading the firmware in a child means we can do that in parallel...
866    // (We ignore SIGCHLD rather than wait for our children.)
867    pid_t pid = fork();
868    if (pid == 0) {
869        Timer t;
870        process_firmware_event(uevent);
871        LOG(INFO) << "loading " << uevent->path << " took " << t.duration() << "s";
872        _exit(EXIT_SUCCESS);
873    } else if (pid == -1) {
874        PLOG(ERROR) << "could not fork to process firmware event for " << uevent->firmware;
875    }
876}
877
878#define UEVENT_MSG_LEN  2048
879
880static inline void handle_device_fd_with(void (handle_uevent)(struct uevent*))
881{
882    char msg[UEVENT_MSG_LEN+2];
883    int n;
884    while ((n = uevent_kernel_multicast_recv(device_fd, msg, UEVENT_MSG_LEN)) > 0) {
885        if(n >= UEVENT_MSG_LEN)   /* overflow -- discard */
886            continue;
887
888        msg[n] = '\0';
889        msg[n+1] = '\0';
890
891        struct uevent uevent;
892        parse_event(msg, &uevent);
893        handle_uevent(&uevent);
894    }
895}
896
897void handle_device_fd()
898{
899    handle_device_fd_with(
900        [](struct uevent *uevent) {
901            if (selinux_status_updated() > 0) {
902                struct selabel_handle *sehandle2;
903                sehandle2 = selinux_android_file_context_handle();
904                if (sehandle2) {
905                    selabel_close(sehandle);
906                    sehandle = sehandle2;
907                }
908            }
909
910            handle_device_event(uevent);
911            handle_firmware_event(uevent);
912        });
913}
914
915/* Coldboot walks parts of the /sys tree and pokes the uevent files
916** to cause the kernel to regenerate device add events that happened
917** before init's device manager was started
918**
919** We drain any pending events from the netlink socket every time
920** we poke another uevent file to make sure we don't overrun the
921** socket's buffer.
922*/
923
924static void do_coldboot(DIR *d)
925{
926    struct dirent *de;
927    int dfd, fd;
928
929    dfd = dirfd(d);
930
931    fd = openat(dfd, "uevent", O_WRONLY);
932    if(fd >= 0) {
933        write(fd, "add\n", 4);
934        close(fd);
935        handle_device_fd();
936    }
937
938    while((de = readdir(d))) {
939        DIR *d2;
940
941        if(de->d_type != DT_DIR || de->d_name[0] == '.')
942            continue;
943
944        fd = openat(dfd, de->d_name, O_RDONLY | O_DIRECTORY);
945        if(fd < 0)
946            continue;
947
948        d2 = fdopendir(fd);
949        if(d2 == 0)
950            close(fd);
951        else {
952            do_coldboot(d2);
953            closedir(d2);
954        }
955    }
956}
957
958static void coldboot(const char *path)
959{
960    std::unique_ptr<DIR, decltype(&closedir)> d(opendir(path), closedir);
961    if(d) {
962        do_coldboot(d.get());
963    }
964}
965
966static void early_uevent_handler(struct uevent *uevent, const char *base, bool is_block)
967{
968    const char *name;
969    char devpath[DEVPATH_LEN];
970
971    if (is_block && strncmp(uevent->subsystem, "block", 5))
972        return;
973
974    name = parse_device_name(uevent, MAX_DEV_NAME);
975    if (!name) {
976        LOG(ERROR) << "Failed to parse dev name from uevent: " << uevent->action
977                   << " " << uevent->partition_name << " " << uevent->partition_num
978                   << " " << uevent->major << ":" << uevent->minor;
979        return;
980    }
981
982    snprintf(devpath, sizeof(devpath), "%s%s", base, name);
983    make_dir(base, 0755);
984
985    dev_t dev = makedev(uevent->major, uevent->minor);
986    mode_t mode = 0600 | (is_block ? S_IFBLK : S_IFCHR);
987    mknod(devpath, mode, dev);
988}
989
990void early_create_dev(const std::string& syspath, early_device_type dev_type)
991{
992    android::base::unique_fd dfd(open(syspath.c_str(), O_RDONLY));
993    if (dfd < 0) {
994        LOG(ERROR) << "Failed to open " << syspath;
995        return;
996    }
997
998    android::base::unique_fd fd(openat(dfd, "uevent", O_WRONLY));
999    if (fd < 0) {
1000        LOG(ERROR) << "Failed to open " << syspath << "/uevent";
1001        return;
1002    }
1003
1004    fcntl(device_fd, F_SETFL, O_NONBLOCK);
1005
1006    write(fd, "add\n", 4);
1007    handle_device_fd_with(dev_type == EARLY_BLOCK_DEV ?
1008        [](struct uevent *uevent) {
1009            early_uevent_handler(uevent, "/dev/block/", true);
1010        } :
1011        [](struct uevent *uevent) {
1012            early_uevent_handler(uevent, "/dev/", false);
1013        });
1014}
1015
1016int early_device_socket_open() {
1017    device_fd = uevent_open_socket(256*1024, true);
1018    return device_fd < 0;
1019}
1020
1021void early_device_socket_close() {
1022    close(device_fd);
1023}
1024
1025void device_init() {
1026    sehandle = selinux_android_file_context_handle();
1027    selinux_status_open(true);
1028
1029    /* is 256K enough? udev uses 16MB! */
1030    device_fd = uevent_open_socket(256*1024, true);
1031    if (device_fd == -1) {
1032        return;
1033    }
1034    fcntl(device_fd, F_SETFL, O_NONBLOCK);
1035
1036    if (access(COLDBOOT_DONE, F_OK) == 0) {
1037        LOG(VERBOSE) << "Skipping coldboot, already done!";
1038        return;
1039    }
1040
1041    Timer t;
1042    coldboot("/sys/class");
1043    coldboot("/sys/block");
1044    coldboot("/sys/devices");
1045    close(open(COLDBOOT_DONE, O_WRONLY|O_CREAT|O_CLOEXEC, 0000));
1046    LOG(INFO) << "Coldboot took " << t.duration() << "s.";
1047}
1048
1049int get_device_fd() {
1050    return device_fd;
1051}
1052