devices.cpp revision 957e4ab0b5c5f0ed006a287ba7cc387ce7db4d27 
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 perms_ {
68    char *name;
69    char *attr;
70    mode_t perm;
71    unsigned int uid;
72    unsigned int gid;
73    unsigned short prefix;
74    unsigned short wildcard;
75};
76
77struct perm_node {
78    struct perms_ dp;
79    struct listnode plist;
80};
81
82struct platform_node {
83    char *name;
84    char *path;
85    int path_len;
86    struct listnode list;
87};
88
89static list_declare(sys_perms);
90static list_declare(dev_perms);
91static list_declare(platform_names);
92
93int add_dev_perms(const char *name, const char *attr,
94                  mode_t perm, unsigned int uid, unsigned int gid,
95                  unsigned short prefix,
96                  unsigned short wildcard) {
97    struct perm_node *node = (perm_node*) calloc(1, sizeof(*node));
98    if (!node)
99        return -ENOMEM;
100
101    node->dp.name = strdup(name);
102    if (!node->dp.name) {
103        free(node);
104        return -ENOMEM;
105    }
106
107    if (attr) {
108        node->dp.attr = strdup(attr);
109        if (!node->dp.attr) {
110            free(node->dp.name);
111            free(node);
112            return -ENOMEM;
113        }
114    }
115
116    node->dp.perm = perm;
117    node->dp.uid = uid;
118    node->dp.gid = gid;
119    node->dp.prefix = prefix;
120    node->dp.wildcard = wildcard;
121
122    if (attr)
123        list_add_tail(&sys_perms, &node->plist);
124    else
125        list_add_tail(&dev_perms, &node->plist);
126
127    return 0;
128}
129
130static bool perm_path_matches(const char *path, struct perms_ *dp)
131{
132    if (dp->prefix) {
133        if (strncmp(path, dp->name, strlen(dp->name)) == 0)
134            return true;
135    } else if (dp->wildcard) {
136        if (fnmatch(dp->name, path, FNM_PATHNAME) == 0)
137            return true;
138    } else {
139        if (strcmp(path, dp->name) == 0)
140            return true;
141    }
142
143    return false;
144}
145
146static bool match_subsystem(perms_* dp, const char* pattern,
147                            const char* path, const char* subsystem) {
148    if (!pattern || !subsystem || strstr(dp->name, subsystem) == NULL) {
149        return false;
150    }
151
152    std::string subsys_path = android::base::StringPrintf(pattern, subsystem, basename(path));
153    return perm_path_matches(subsys_path.c_str(), dp);
154}
155
156static void fixup_sys_perms(const char* upath, const char* subsystem) {
157    // upaths omit the "/sys" that paths in this list
158    // contain, so we prepend it...
159    std::string path = std::string(SYSFS_PREFIX) + upath;
160
161    listnode* node;
162    list_for_each(node, &sys_perms) {
163        perms_* dp = &(node_to_item(node, perm_node, plist))->dp;
164        if (match_subsystem(dp, SYSFS_PREFIX "/class/%s/%s", path.c_str(), subsystem)) {
165            ; // matched
166        } else if (match_subsystem(dp, SYSFS_PREFIX "/bus/%s/devices/%s", path.c_str(), subsystem)) {
167            ; // matched
168        } else if (!perm_path_matches(path.c_str(), dp)) {
169            continue;
170        }
171
172        std::string attr_file = path + "/" + dp->attr;
173        LOG(INFO) << "fixup " << attr_file
174                  << " " << dp->uid << " " << dp->gid << " " << std::oct << dp->perm;
175        chown(attr_file.c_str(), dp->uid, dp->gid);
176        chmod(attr_file.c_str(), dp->perm);
177    }
178
179    if (access(path.c_str(), F_OK) == 0) {
180        LOG(VERBOSE) << "restorecon_recursive: " << path;
181        restorecon(path.c_str(), SELINUX_ANDROID_RESTORECON_RECURSE);
182    }
183}
184
185static mode_t get_device_perm(const char *path, const char **links,
186                unsigned *uid, unsigned *gid)
187{
188    struct listnode *node;
189    struct perm_node *perm_node;
190    struct perms_ *dp;
191
192    /* search the perms list in reverse so that ueventd.$hardware can
193     * override ueventd.rc
194     */
195    list_for_each_reverse(node, &dev_perms) {
196        bool match = false;
197
198        perm_node = node_to_item(node, struct perm_node, plist);
199        dp = &perm_node->dp;
200
201        if (perm_path_matches(path, dp)) {
202            match = true;
203        } else {
204            if (links) {
205                int i;
206                for (i = 0; links[i]; i++) {
207                    if (perm_path_matches(links[i], dp)) {
208                        match = true;
209                        break;
210                    }
211                }
212            }
213        }
214
215        if (match) {
216            *uid = dp->uid;
217            *gid = dp->gid;
218            return dp->perm;
219        }
220    }
221    /* Default if nothing found. */
222    *uid = 0;
223    *gid = 0;
224    return 0600;
225}
226
227static void make_device(const char *path,
228                        const char */*upath*/,
229                        int block, int major, int minor,
230                        const char **links)
231{
232    unsigned uid;
233    unsigned gid;
234    mode_t mode;
235    dev_t dev;
236    char *secontext = NULL;
237
238    mode = get_device_perm(path, links, &uid, &gid) | (block ? S_IFBLK : S_IFCHR);
239
240    if (sehandle) {
241        if (selabel_lookup_best_match(sehandle, &secontext, path, links, mode)) {
242            PLOG(ERROR) << "Device '" << path << "' not created; cannot find SELinux label";
243            return;
244        }
245        setfscreatecon(secontext);
246    }
247
248    dev = makedev(major, minor);
249    /* Temporarily change egid to avoid race condition setting the gid of the
250     * device node. Unforunately changing the euid would prevent creation of
251     * some device nodes, so the uid has to be set with chown() and is still
252     * racy. Fixing the gid race at least fixed the issue with system_server
253     * opening dynamic input devices under the AID_INPUT gid. */
254    setegid(gid);
255    /* If the node already exists update its SELinux label to handle cases when
256     * it was created with the wrong context during coldboot procedure. */
257    if (mknod(path, mode, dev) && (errno == EEXIST) && secontext) {
258
259        char* fcon = nullptr;
260        int rc = lgetfilecon(path, &fcon);
261        if (rc < 0) {
262            PLOG(ERROR) << "Cannot get SELinux label on '" << path << "' device";
263            goto out;
264        }
265
266        bool different = strcmp(fcon, secontext) != 0;
267        freecon(fcon);
268
269        if (different && lsetfilecon(path, secontext)) {
270            PLOG(ERROR) << "Cannot set '" << secontext << "' SELinux label on '" << path << "' device";
271        }
272    }
273
274out:
275    chown(path, uid, -1);
276    setegid(AID_ROOT);
277
278    if (secontext) {
279        freecon(secontext);
280        setfscreatecon(NULL);
281    }
282}
283
284static void add_platform_device(const char *path)
285{
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
327static void remove_platform_device(const char *path)
328{
329    struct listnode *node;
330    struct platform_node *bus;
331
332    list_for_each_reverse(node, &platform_names) {
333        bus = node_to_item(node, struct platform_node, list);
334        if (!strcmp(path, bus->path)) {
335            LOG(INFO) << "removing platform device " << bus->name;
336            free(bus->path);
337            list_remove(node);
338            free(bus);
339            return;
340        }
341    }
342}
343
344/* Given a path that may start with a PCI device, populate the supplied buffer
345 * with the PCI domain/bus number and the peripheral ID and return 0.
346 * If it doesn't start with a PCI device, or there is some error, return -1 */
347static int find_pci_device_prefix(const char *path, char *buf, ssize_t buf_sz)
348{
349    const char *start, *end;
350
351    if (strncmp(path, "/devices/pci", 12))
352        return -1;
353
354    /* Beginning of the prefix is the initial "pci" after "/devices/" */
355    start = path + 9;
356
357    /* End of the prefix is two path '/' later, capturing the domain/bus number
358     * and the peripheral ID. Example: pci0000:00/0000:00:1f.2 */
359    end = strchr(start, '/');
360    if (!end)
361        return -1;
362    end = strchr(end + 1, '/');
363    if (!end)
364        return -1;
365
366    /* Make sure we have enough room for the string plus null terminator */
367    if (end - start + 1 > buf_sz)
368        return -1;
369
370    strncpy(buf, start, end - start);
371    buf[end - start] = '\0';
372    return 0;
373}
374
375static void parse_event(const char *msg, struct uevent *uevent)
376{
377    uevent->action = "";
378    uevent->path = "";
379    uevent->subsystem = "";
380    uevent->firmware = "";
381    uevent->major = -1;
382    uevent->minor = -1;
383    uevent->partition_name = NULL;
384    uevent->partition_num = -1;
385    uevent->device_name = NULL;
386
387        /* currently ignoring SEQNUM */
388    while(*msg) {
389        if(!strncmp(msg, "ACTION=", 7)) {
390            msg += 7;
391            uevent->action = msg;
392        } else if(!strncmp(msg, "DEVPATH=", 8)) {
393            msg += 8;
394            uevent->path = msg;
395        } else if(!strncmp(msg, "SUBSYSTEM=", 10)) {
396            msg += 10;
397            uevent->subsystem = msg;
398        } else if(!strncmp(msg, "FIRMWARE=", 9)) {
399            msg += 9;
400            uevent->firmware = msg;
401        } else if(!strncmp(msg, "MAJOR=", 6)) {
402            msg += 6;
403            uevent->major = atoi(msg);
404        } else if(!strncmp(msg, "MINOR=", 6)) {
405            msg += 6;
406            uevent->minor = atoi(msg);
407        } else if(!strncmp(msg, "PARTN=", 6)) {
408            msg += 6;
409            uevent->partition_num = atoi(msg);
410        } else if(!strncmp(msg, "PARTNAME=", 9)) {
411            msg += 9;
412            uevent->partition_name = msg;
413        } else if(!strncmp(msg, "DEVNAME=", 8)) {
414            msg += 8;
415            uevent->device_name = msg;
416        }
417
418        /* advance to after the next \0 */
419        while(*msg++)
420            ;
421    }
422
423    if (LOG_UEVENTS) {
424        LOG(INFO) << android::base::StringPrintf("event { '%s', '%s', '%s', '%s', %d, %d }",
425                                                 uevent->action, uevent->path, uevent->subsystem,
426                                                 uevent->firmware, uevent->major, uevent->minor);
427    }
428}
429
430static char **get_character_device_symlinks(struct uevent *uevent)
431{
432    const char *parent;
433    const char *slash;
434    char **links;
435    int link_num = 0;
436    int width;
437    struct platform_node *pdev;
438
439    pdev = find_platform_device(uevent->path);
440    if (!pdev)
441        return NULL;
442
443    links = (char**) malloc(sizeof(char *) * 2);
444    if (!links)
445        return NULL;
446    memset(links, 0, sizeof(char *) * 2);
447
448    /* skip "/devices/platform/<driver>" */
449    parent = strchr(uevent->path + pdev->path_len, '/');
450    if (!parent)
451        goto err;
452
453    if (!strncmp(parent, "/usb", 4)) {
454        /* skip root hub name and device. use device interface */
455        while (*++parent && *parent != '/');
456        if (*parent)
457            while (*++parent && *parent != '/');
458        if (!*parent)
459            goto err;
460        slash = strchr(++parent, '/');
461        if (!slash)
462            goto err;
463        width = slash - parent;
464        if (width <= 0)
465            goto err;
466
467        if (asprintf(&links[link_num], "/dev/usb/%s%.*s", uevent->subsystem, width, parent) > 0)
468            link_num++;
469        else
470            links[link_num] = NULL;
471        mkdir("/dev/usb", 0755);
472    }
473    else {
474        goto err;
475    }
476
477    return links;
478err:
479    free(links);
480    return NULL;
481}
482
483static char **get_block_device_symlinks(struct uevent *uevent)
484{
485    const char *device;
486    struct platform_node *pdev;
487    const char *slash;
488    const char *type;
489    char buf[256];
490    char link_path[256];
491    int link_num = 0;
492    char *p;
493
494    pdev = find_platform_device(uevent->path);
495    if (pdev) {
496        device = pdev->name;
497        type = "platform";
498    } else if (!find_pci_device_prefix(uevent->path, buf, sizeof(buf))) {
499        device = buf;
500        type = "pci";
501    } else {
502        return NULL;
503    }
504
505    char **links = (char**) malloc(sizeof(char *) * 4);
506    if (!links)
507        return NULL;
508    memset(links, 0, sizeof(char *) * 4);
509
510    LOG(INFO) << "found " << type << " device " << device;
511
512    snprintf(link_path, sizeof(link_path), "/dev/block/%s/%s", type, device);
513
514    if (uevent->partition_name) {
515        p = strdup(uevent->partition_name);
516        sanitize(p);
517        if (strcmp(uevent->partition_name, p)) {
518            LOG(VERBOSE) << "Linking partition '" << uevent->partition_name << "' as '" << p << "'";
519        }
520        if (asprintf(&links[link_num], "%s/by-name/%s", link_path, p) > 0)
521            link_num++;
522        else
523            links[link_num] = NULL;
524        free(p);
525    }
526
527    if (uevent->partition_num >= 0) {
528        if (asprintf(&links[link_num], "%s/by-num/p%d", link_path, uevent->partition_num) > 0)
529            link_num++;
530        else
531            links[link_num] = NULL;
532    }
533
534    slash = strrchr(uevent->path, '/');
535    if (asprintf(&links[link_num], "%s/%s", link_path, slash + 1) > 0)
536        link_num++;
537    else
538        links[link_num] = NULL;
539
540    return links;
541}
542
543static void make_link_init(const char* oldpath, const char* newpath) {
544  const char* slash = strrchr(newpath, '/');
545  if (!slash) return;
546
547  if (mkdir_recursive(dirname(newpath), 0755)) {
548    PLOG(ERROR) << "Failed to create directory " << dirname(newpath);
549  }
550
551  if (symlink(oldpath, newpath) && errno != EEXIST) {
552    PLOG(ERROR) << "Failed to symlink " << oldpath << " to " << newpath;
553  }
554}
555
556static void remove_link(const char* oldpath, const char* newpath) {
557  std::string path;
558  if (android::base::Readlink(newpath, &path) && path == oldpath) unlink(newpath);
559}
560
561static void handle_device(const char *action, const char *devpath,
562        const char *path, int block, int major, int minor, char **links)
563{
564    if(!strcmp(action, "add")) {
565        make_device(devpath, path, block, major, minor, (const char **)links);
566        if (links) {
567            for (int i = 0; links[i]; i++) {
568                make_link_init(devpath, links[i]);
569            }
570        }
571    }
572
573    if(!strcmp(action, "remove")) {
574        if (links) {
575            for (int i = 0; links[i]; i++) {
576                remove_link(devpath, links[i]);
577            }
578        }
579        unlink(devpath);
580    }
581
582    if (links) {
583        for (int i = 0; links[i]; i++) {
584            free(links[i]);
585        }
586        free(links);
587    }
588}
589
590static void handle_platform_device_event(struct uevent *uevent)
591{
592    const char *path = uevent->path;
593
594    if (!strcmp(uevent->action, "add"))
595        add_platform_device(path);
596    else if (!strcmp(uevent->action, "remove"))
597        remove_platform_device(path);
598}
599
600static const char *parse_device_name(struct uevent *uevent, unsigned int len)
601{
602    const char *name;
603
604    /* if it's not a /dev device, nothing else to do */
605    if((uevent->major < 0) || (uevent->minor < 0))
606        return NULL;
607
608    /* do we have a name? */
609    name = strrchr(uevent->path, '/');
610    if(!name)
611        return NULL;
612    name++;
613
614    /* too-long names would overrun our buffer */
615    if(strlen(name) > len) {
616        LOG(ERROR) << "DEVPATH=" << name << " exceeds " << len << "-character limit on filename; ignoring event";
617        return NULL;
618    }
619
620    return name;
621}
622
623#define DEVPATH_LEN 96
624#define MAX_DEV_NAME 64
625
626static void handle_block_device_event(struct uevent *uevent)
627{
628    const char *base = "/dev/block/";
629    const char *name;
630    char devpath[DEVPATH_LEN];
631    char **links = NULL;
632
633    name = parse_device_name(uevent, MAX_DEV_NAME);
634    if (!name)
635        return;
636
637    snprintf(devpath, sizeof(devpath), "%s%s", base, name);
638    make_dir(base, 0755);
639
640    if (!strncmp(uevent->path, "/devices/", 9))
641        links = get_block_device_symlinks(uevent);
642
643    handle_device(uevent->action, devpath, uevent->path, 1,
644            uevent->major, uevent->minor, links);
645}
646
647static bool assemble_devpath(char *devpath, const char *dirname,
648        const char *devname)
649{
650    int s = snprintf(devpath, DEVPATH_LEN, "%s/%s", dirname, devname);
651    if (s < 0) {
652        PLOG(ERROR) << "failed to assemble device path; ignoring event";
653        return false;
654    } else if (s >= DEVPATH_LEN) {
655        LOG(ERROR) << dirname << "/" << devname
656                   << " exceeds " << DEVPATH_LEN << "-character limit on path; ignoring event";
657        return false;
658    }
659    return true;
660}
661
662static void mkdir_recursive_for_devpath(const char *devpath)
663{
664    char dir[DEVPATH_LEN];
665    char *slash;
666
667    strcpy(dir, devpath);
668    slash = strrchr(dir, '/');
669    *slash = '\0';
670    mkdir_recursive(dir, 0755);
671}
672
673static void handle_generic_device_event(struct uevent *uevent)
674{
675    const char *base;
676    const char *name;
677    char devpath[DEVPATH_LEN] = {0};
678    char **links = NULL;
679
680    name = parse_device_name(uevent, MAX_DEV_NAME);
681    if (!name)
682        return;
683
684    struct ueventd_subsystem *subsystem =
685            ueventd_subsystem_find_by_name(uevent->subsystem);
686
687    if (subsystem) {
688        const char *devname;
689
690        switch (subsystem->devname_src) {
691        case DEVNAME_UEVENT_DEVNAME:
692            devname = uevent->device_name;
693            break;
694
695        case DEVNAME_UEVENT_DEVPATH:
696            devname = name;
697            break;
698
699        default:
700            LOG(ERROR) << uevent->subsystem << " subsystem's devpath option is not set; ignoring event";
701            return;
702        }
703
704        if (!assemble_devpath(devpath, subsystem->dirname, devname))
705            return;
706        mkdir_recursive_for_devpath(devpath);
707    } else if (!strncmp(uevent->subsystem, "usb", 3)) {
708         if (!strcmp(uevent->subsystem, "usb")) {
709            if (uevent->device_name) {
710                if (!assemble_devpath(devpath, "/dev", uevent->device_name))
711                    return;
712                mkdir_recursive_for_devpath(devpath);
713             }
714             else {
715                 /* This imitates the file system that would be created
716                  * if we were using devfs instead.
717                  * Minors are broken up into groups of 128, starting at "001"
718                  */
719                 int bus_id = uevent->minor / 128 + 1;
720                 int device_id = uevent->minor % 128 + 1;
721                 /* build directories */
722                 make_dir("/dev/bus", 0755);
723                 make_dir("/dev/bus/usb", 0755);
724                 snprintf(devpath, sizeof(devpath), "/dev/bus/usb/%03d", bus_id);
725                 make_dir(devpath, 0755);
726                 snprintf(devpath, sizeof(devpath), "/dev/bus/usb/%03d/%03d", bus_id, device_id);
727             }
728         } else {
729             /* ignore other USB events */
730             return;
731         }
732     } else if (!strncmp(uevent->subsystem, "graphics", 8)) {
733         base = "/dev/graphics/";
734         make_dir(base, 0755);
735     } else if (!strncmp(uevent->subsystem, "drm", 3)) {
736         base = "/dev/dri/";
737         make_dir(base, 0755);
738     } else if (!strncmp(uevent->subsystem, "oncrpc", 6)) {
739         base = "/dev/oncrpc/";
740         make_dir(base, 0755);
741     } else if (!strncmp(uevent->subsystem, "adsp", 4)) {
742         base = "/dev/adsp/";
743         make_dir(base, 0755);
744     } else if (!strncmp(uevent->subsystem, "msm_camera", 10)) {
745         base = "/dev/msm_camera/";
746         make_dir(base, 0755);
747     } else if(!strncmp(uevent->subsystem, "input", 5)) {
748         base = "/dev/input/";
749         make_dir(base, 0755);
750     } else if(!strncmp(uevent->subsystem, "mtd", 3)) {
751         base = "/dev/mtd/";
752         make_dir(base, 0755);
753     } else if(!strncmp(uevent->subsystem, "sound", 5)) {
754         base = "/dev/snd/";
755         make_dir(base, 0755);
756     } else if(!strncmp(uevent->subsystem, "misc", 4) && !strncmp(name, "log_", 4)) {
757         LOG(INFO) << "kernel logger is deprecated";
758         base = "/dev/log/";
759         make_dir(base, 0755);
760         name += 4;
761     } else
762         base = "/dev/";
763     links = get_character_device_symlinks(uevent);
764
765     if (!devpath[0])
766         snprintf(devpath, sizeof(devpath), "%s%s", base, name);
767
768     handle_device(uevent->action, devpath, uevent->path, 0,
769             uevent->major, uevent->minor, links);
770}
771
772static void handle_device_event(struct uevent *uevent)
773{
774    if (!strcmp(uevent->action,"add") || !strcmp(uevent->action, "change") || !strcmp(uevent->action, "online"))
775        fixup_sys_perms(uevent->path, uevent->subsystem);
776
777    if (!strncmp(uevent->subsystem, "block", 5)) {
778        handle_block_device_event(uevent);
779    } else if (!strncmp(uevent->subsystem, "platform", 8)) {
780        handle_platform_device_event(uevent);
781    } else {
782        handle_generic_device_event(uevent);
783    }
784}
785
786static void load_firmware(uevent* uevent, const std::string& root,
787                          int fw_fd, size_t fw_size,
788                          int loading_fd, int data_fd) {
789    // Start transfer.
790    android::base::WriteFully(loading_fd, "1", 1);
791
792    // Copy the firmware.
793    int rc = sendfile(data_fd, fw_fd, nullptr, fw_size);
794    if (rc == -1) {
795        PLOG(ERROR) << "firmware: sendfile failed { '" << root << "', '" << uevent->firmware << "' }";
796    }
797
798    // Tell the firmware whether to abort or commit.
799    const char* response = (rc != -1) ? "0" : "-1";
800    android::base::WriteFully(loading_fd, response, strlen(response));
801}
802
803static int is_booting() {
804    return access("/dev/.booting", F_OK) == 0;
805}
806
807static void process_firmware_event(uevent* uevent) {
808    int booting = is_booting();
809
810    LOG(INFO) << "firmware: loading '" << uevent->firmware << "' for '" << uevent->path << "'";
811
812    std::string root = android::base::StringPrintf("/sys%s", uevent->path);
813    std::string loading = root + "/loading";
814    std::string data = root + "/data";
815
816    android::base::unique_fd loading_fd(open(loading.c_str(), O_WRONLY|O_CLOEXEC));
817    if (loading_fd == -1) {
818        PLOG(ERROR) << "couldn't open firmware loading fd for " << uevent->firmware;
819        return;
820    }
821
822    android::base::unique_fd data_fd(open(data.c_str(), O_WRONLY|O_CLOEXEC));
823    if (data_fd == -1) {
824        PLOG(ERROR) << "couldn't open firmware data fd for " << uevent->firmware;
825        return;
826    }
827
828try_loading_again:
829    for (size_t i = 0; i < arraysize(firmware_dirs); i++) {
830        std::string file = android::base::StringPrintf("%s/%s", firmware_dirs[i], uevent->firmware);
831        android::base::unique_fd fw_fd(open(file.c_str(), O_RDONLY|O_CLOEXEC));
832        struct stat sb;
833        if (fw_fd != -1 && fstat(fw_fd, &sb) != -1) {
834            load_firmware(uevent, root, fw_fd, sb.st_size, loading_fd, data_fd);
835            return;
836        }
837    }
838
839    if (booting) {
840        // If we're not fully booted, we may be missing
841        // filesystems needed for firmware, wait and retry.
842        std::this_thread::sleep_for(100ms);
843        booting = is_booting();
844        goto try_loading_again;
845    }
846
847    LOG(ERROR) << "firmware: could not find firmware for " << uevent->firmware;
848
849    // Write "-1" as our response to the kernel's firmware request, since we have nothing for it.
850    write(loading_fd, "-1", 2);
851}
852
853static void handle_firmware_event(uevent* uevent) {
854    if (strcmp(uevent->subsystem, "firmware")) return;
855    if (strcmp(uevent->action, "add")) return;
856
857    // Loading the firmware in a child means we can do that in parallel...
858    // (We ignore SIGCHLD rather than wait for our children.)
859    pid_t pid = fork();
860    if (pid == 0) {
861        Timer t;
862        process_firmware_event(uevent);
863        LOG(INFO) << "loading " << uevent->path << " took " << t;
864        _exit(EXIT_SUCCESS);
865    } else if (pid == -1) {
866        PLOG(ERROR) << "could not fork to process firmware event for " << uevent->firmware;
867    }
868}
869
870static bool inline should_stop_coldboot(coldboot_action_t act)
871{
872    return (act == COLDBOOT_STOP || act == COLDBOOT_FINISH);
873}
874
875#define UEVENT_MSG_LEN  2048
876
877template<typename T>
878static inline coldboot_action_t handle_device_fd_with(const T& handle_uevent)
879{
880    char msg[UEVENT_MSG_LEN+2];
881    int n;
882    while ((n = uevent_kernel_multicast_recv(device_fd, msg, UEVENT_MSG_LEN)) > 0) {
883        if(n >= UEVENT_MSG_LEN)   /* overflow -- discard */
884            continue;
885
886        msg[n] = '\0';
887        msg[n+1] = '\0';
888
889        struct uevent uevent;
890        parse_event(msg, &uevent);
891        coldboot_action_t act = handle_uevent(&uevent);
892        if (should_stop_coldboot(act))
893            return act;
894    }
895
896    return COLDBOOT_CONTINUE;
897}
898
899coldboot_action_t handle_device_fd(coldboot_callback fn)
900{
901    coldboot_action_t ret = handle_device_fd_with(
902        [&](uevent* uevent) -> coldboot_action_t {
903            if (selinux_status_updated() > 0) {
904                struct selabel_handle *sehandle2;
905                sehandle2 = selinux_android_file_context_handle();
906                if (sehandle2) {
907                    selabel_close(sehandle);
908                    sehandle = sehandle2;
909                }
910            }
911
912            // default is to always create the devices
913            coldboot_action_t act = COLDBOOT_CREATE;
914            if (fn) {
915                act = fn(uevent);
916            }
917
918            if (act == COLDBOOT_CREATE || act == COLDBOOT_STOP) {
919                handle_device_event(uevent);
920                handle_firmware_event(uevent);
921            }
922
923            return act;
924        });
925
926    return ret;
927}
928
929/* Coldboot walks parts of the /sys tree and pokes the uevent files
930** to cause the kernel to regenerate device add events that happened
931** before init's device manager was started
932**
933** We drain any pending events from the netlink socket every time
934** we poke another uevent file to make sure we don't overrun the
935** socket's buffer.
936*/
937
938static coldboot_action_t do_coldboot(DIR *d, coldboot_callback fn)
939{
940    struct dirent *de;
941    int dfd, fd;
942    coldboot_action_t act = COLDBOOT_CONTINUE;
943
944    dfd = dirfd(d);
945
946    fd = openat(dfd, "uevent", O_WRONLY);
947    if (fd >= 0) {
948        write(fd, "add\n", 4);
949        close(fd);
950        act = handle_device_fd(fn);
951        if (should_stop_coldboot(act))
952            return act;
953    }
954
955    while (!should_stop_coldboot(act) && (de = readdir(d))) {
956        DIR *d2;
957
958        if(de->d_type != DT_DIR || de->d_name[0] == '.')
959            continue;
960
961        fd = openat(dfd, de->d_name, O_RDONLY | O_DIRECTORY);
962        if(fd < 0)
963            continue;
964
965        d2 = fdopendir(fd);
966        if(d2 == 0)
967            close(fd);
968        else {
969            act = do_coldboot(d2, fn);
970            closedir(d2);
971        }
972    }
973
974    // default is always to continue looking for uevents
975    return act;
976}
977
978static coldboot_action_t coldboot(const char *path, coldboot_callback fn)
979{
980    std::unique_ptr<DIR, decltype(&closedir)> d(opendir(path), closedir);
981    if (d) {
982        return do_coldboot(d.get(), fn);
983    }
984
985    return COLDBOOT_CONTINUE;
986}
987
988static coldboot_action_t early_uevent_handler(struct uevent *uevent, const char *base, bool is_block)
989{
990    const char *name;
991    char devpath[DEVPATH_LEN];
992
993    if (is_block && strncmp(uevent->subsystem, "block", 5))
994        return COLDBOOT_STOP;
995
996    name = parse_device_name(uevent, MAX_DEV_NAME);
997    if (!name) {
998        LOG(ERROR) << "Failed to parse dev name from uevent: " << uevent->action
999                   << " " << uevent->partition_name << " " << uevent->partition_num
1000                   << " " << uevent->major << ":" << uevent->minor;
1001        return COLDBOOT_STOP;
1002    }
1003
1004    snprintf(devpath, sizeof(devpath), "%s%s", base, name);
1005    make_dir(base, 0755);
1006
1007    dev_t dev = makedev(uevent->major, uevent->minor);
1008    mode_t mode = 0600 | (is_block ? S_IFBLK : S_IFCHR);
1009    mknod(devpath, mode, dev);
1010
1011    return COLDBOOT_STOP;
1012}
1013
1014void early_create_dev(const std::string& syspath, early_device_type dev_type)
1015{
1016    android::base::unique_fd dfd(open(syspath.c_str(), O_RDONLY));
1017    if (dfd < 0) {
1018        LOG(ERROR) << "Failed to open " << syspath;
1019        return;
1020    }
1021
1022    android::base::unique_fd fd(openat(dfd, "uevent", O_WRONLY));
1023    if (fd < 0) {
1024        LOG(ERROR) << "Failed to open " << syspath << "/uevent";
1025        return;
1026    }
1027
1028    fcntl(device_fd, F_SETFL, O_NONBLOCK);
1029
1030    write(fd, "add\n", 4);
1031    handle_device_fd_with(dev_type == EARLY_BLOCK_DEV ?
1032        [](uevent* uevent) -> coldboot_action_t {
1033            return early_uevent_handler(uevent, "/dev/block/", true);
1034        } :
1035        [](uevent* uevent) -> coldboot_action_t {
1036            return early_uevent_handler(uevent, "/dev/", false);
1037        });
1038}
1039
1040int early_device_socket_open() {
1041    device_fd = uevent_open_socket(256*1024, true);
1042    return device_fd < 0;
1043}
1044
1045void early_device_socket_close() {
1046    close(device_fd);
1047}
1048
1049void device_init(const char* path, coldboot_callback fn) {
1050    sehandle = selinux_android_file_context_handle();
1051    selinux_status_open(true);
1052
1053    /* is 256K enough? udev uses 16MB! */
1054    device_fd = uevent_open_socket(256*1024, true);
1055    if (device_fd == -1) {
1056        return;
1057    }
1058    fcntl(device_fd, F_SETFL, O_NONBLOCK);
1059
1060    if (access(COLDBOOT_DONE, F_OK) == 0) {
1061        LOG(VERBOSE) << "Skipping coldboot, already done!";
1062        return;
1063    }
1064
1065    Timer t;
1066    coldboot_action_t act;
1067    if (!path) {
1068        act = coldboot("/sys/class", fn);
1069        if (!should_stop_coldboot(act)) {
1070            act = coldboot("/sys/block", fn);
1071            if (!should_stop_coldboot(act)) {
1072                act = coldboot("/sys/devices", fn);
1073            }
1074        }
1075    } else {
1076        act = coldboot(path, fn);
1077    }
1078
1079    // If we have a callback, then do as it says. If no, then the default is
1080    // to always create COLDBOOT_DONE file.
1081    if (!fn || (act == COLDBOOT_FINISH)) {
1082        close(open(COLDBOOT_DONE, O_WRONLY|O_CREAT|O_CLOEXEC, 0000));
1083    }
1084
1085    LOG(INFO) << "Coldboot took " << t;
1086}
1087
1088int get_device_fd() {
1089    return device_fd;
1090}
1091