devices.cpp revision 120add07ab2aa03cb7c073ef7629817b41643dc1 
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 <algorithm>
36#include <memory>
37#include <string>
38#include <thread>
39#include <vector>
40
41#include <android-base/file.h>
42#include <android-base/logging.h>
43#include <android-base/stringprintf.h>
44#include <android-base/strings.h>
45#include <android-base/unique_fd.h>
46#include <cutils/list.h>
47#include <cutils/uevent.h>
48#include <private/android_filesystem_config.h>
49#include <selinux/android.h>
50#include <selinux/avc.h>
51#include <selinux/label.h>
52#include <selinux/selinux.h>
53
54#include "devices.h"
55#include "ueventd_parser.h"
56#include "util.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 android::base::unique_fd device_fd;
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 std::vector<std::string>& links,
186                              unsigned* uid, unsigned* gid) {
187    struct listnode *node;
188    struct perm_node *perm_node;
189    struct perms_ *dp;
190
191    /* search the perms list in reverse so that ueventd.$hardware can
192     * override ueventd.rc
193     */
194    list_for_each_reverse(node, &dev_perms) {
195        perm_node = node_to_item(node, struct perm_node, plist);
196        dp = &perm_node->dp;
197
198        if (perm_path_matches(path, dp) ||
199            std::any_of(links.begin(), links.end(),
200                        [dp](const auto& link) { return perm_path_matches(link.c_str(), dp); })) {
201            *uid = dp->uid;
202            *gid = dp->gid;
203            return dp->perm;
204        }
205    }
206    /* Default if nothing found. */
207    *uid = 0;
208    *gid = 0;
209    return 0600;
210}
211
212static void make_device(const char* path, const char* /*upath*/, int block, int major, int minor,
213                        const std::vector<std::string>& links) {
214    unsigned uid;
215    unsigned gid;
216    mode_t mode;
217    dev_t dev;
218    char *secontext = NULL;
219
220    mode = get_device_perm(path, links, &uid, &gid) | (block ? S_IFBLK : S_IFCHR);
221
222    if (sehandle) {
223        std::vector<const char*> c_links;
224        for (const auto& link : links) {
225            c_links.emplace_back(link.c_str());
226        }
227        c_links.emplace_back(nullptr);
228        if (selabel_lookup_best_match(sehandle, &secontext, path, &c_links[0], mode)) {
229            PLOG(ERROR) << "Device '" << path << "' not created; cannot find SELinux label";
230            return;
231        }
232        setfscreatecon(secontext);
233    }
234
235    dev = makedev(major, minor);
236    /* Temporarily change egid to avoid race condition setting the gid of the
237     * device node. Unforunately changing the euid would prevent creation of
238     * some device nodes, so the uid has to be set with chown() and is still
239     * racy. Fixing the gid race at least fixed the issue with system_server
240     * opening dynamic input devices under the AID_INPUT gid. */
241    if (setegid(gid)) {
242        PLOG(ERROR) << "setegid(" << gid << ") for " << path << " device failed";
243        goto out;
244    }
245    /* If the node already exists update its SELinux label to handle cases when
246     * it was created with the wrong context during coldboot procedure. */
247    if (mknod(path, mode, dev) && (errno == EEXIST) && secontext) {
248
249        char* fcon = nullptr;
250        int rc = lgetfilecon(path, &fcon);
251        if (rc < 0) {
252            PLOG(ERROR) << "Cannot get SELinux label on '" << path << "' device";
253            goto out;
254        }
255
256        bool different = strcmp(fcon, secontext) != 0;
257        freecon(fcon);
258
259        if (different && lsetfilecon(path, secontext)) {
260            PLOG(ERROR) << "Cannot set '" << secontext << "' SELinux label on '" << path << "' device";
261        }
262    }
263
264out:
265    chown(path, uid, -1);
266    if (setegid(AID_ROOT)) {
267        PLOG(FATAL) << "setegid(AID_ROOT) failed";
268    }
269
270    if (secontext) {
271        freecon(secontext);
272        setfscreatecon(NULL);
273    }
274}
275
276void add_platform_device(const char* path) {
277    int path_len = strlen(path);
278    struct platform_node *bus;
279    const char *name = path;
280
281    if (!strncmp(path, "/devices/", 9)) {
282        name += 9;
283        if (!strncmp(name, "platform/", 9))
284            name += 9;
285    }
286
287    LOG(VERBOSE) << "adding platform device " << name << " (" << path << ")";
288
289    bus = (platform_node*) calloc(1, sizeof(struct platform_node));
290    bus->path = strdup(path);
291    bus->path_len = path_len;
292    bus->name = bus->path + (name - path);
293    list_add_tail(&platform_names, &bus->list);
294}
295
296/*
297 * given a path that may start with a platform device, find the length of the
298 * platform device prefix.  If it doesn't start with a platform device, return
299 * 0.
300 */
301static struct platform_node *find_platform_device(const char *path)
302{
303    int path_len = strlen(path);
304    struct listnode *node;
305    struct platform_node *bus;
306
307    list_for_each_reverse(node, &platform_names) {
308        bus = node_to_item(node, struct platform_node, list);
309        if ((bus->path_len < path_len) &&
310                (path[bus->path_len] == '/') &&
311                !strncmp(path, bus->path, bus->path_len))
312            return bus;
313    }
314
315    return NULL;
316}
317
318void remove_platform_device(const char* path) {
319    struct listnode *node;
320    struct platform_node *bus;
321
322    list_for_each_reverse(node, &platform_names) {
323        bus = node_to_item(node, struct platform_node, list);
324        if (!strcmp(path, bus->path)) {
325            LOG(INFO) << "removing platform device " << bus->name;
326            free(bus->path);
327            list_remove(node);
328            free(bus);
329            return;
330        }
331    }
332}
333
334static void destroy_platform_devices() {
335    struct listnode* node;
336    struct listnode* n;
337    struct platform_node* bus;
338
339    list_for_each_safe(node, n, &platform_names) {
340        list_remove(node);
341        bus = node_to_item(node, struct platform_node, list);
342        free(bus->path);
343        free(bus);
344    }
345}
346
347/* Given a path that may start with a PCI device, populate the supplied buffer
348 * with the PCI domain/bus number and the peripheral ID and return 0.
349 * If it doesn't start with a PCI device, or there is some error, return -1 */
350static bool find_pci_device_prefix(const std::string& path, std::string* result) {
351    result->clear();
352
353    if (!android::base::StartsWith(path, "/devices/pci")) return false;
354
355    /* Beginning of the prefix is the initial "pci" after "/devices/" */
356    std::string::size_type start = 9;
357
358    /* End of the prefix is two path '/' later, capturing the domain/bus number
359     * and the peripheral ID. Example: pci0000:00/0000:00:1f.2 */
360    auto end = path.find('/', start);
361    if (end == std::string::npos) return false;
362
363    end = path.find('/', end + 1);
364    if (end == std::string::npos) return false;
365
366    auto length = end - start;
367    if (length <= 4) {
368        // The minimum string that will get to this check is 'pci/', which is malformed,
369        // so return false
370        return false;
371    }
372
373    *result = path.substr(start, length);
374    return true;
375}
376
377/* Given a path that may start with a virtual block device, populate
378 * the supplied buffer with the virtual block device ID and return 0.
379 * If it doesn't start with a virtual block device, or there is some
380 * error, return -1 */
381static bool find_vbd_device_prefix(const std::string& path, std::string* result) {
382    result->clear();
383
384    if (!android::base::StartsWith(path, "/devices/vbd-")) return false;
385
386    /* Beginning of the prefix is the initial "vbd-" after "/devices/" */
387    std::string::size_type start = 13;
388
389    /* End of the prefix is one path '/' later, capturing the
390       virtual block device ID. Example: 768 */
391    auto end = path.find('/', start);
392    if (end == std::string::npos) return false;
393
394    auto length = end - start;
395    if (length == 0) return false;
396
397    *result = path.substr(start, length);
398    return true;
399}
400
401static void parse_event(const char *msg, struct uevent *uevent)
402{
403    uevent->action = "";
404    uevent->path = "";
405    uevent->subsystem = "";
406    uevent->firmware = "";
407    uevent->major = -1;
408    uevent->minor = -1;
409    uevent->partition_name = NULL;
410    uevent->partition_num = -1;
411    uevent->device_name = NULL;
412
413        /* currently ignoring SEQNUM */
414    while(*msg) {
415        if(!strncmp(msg, "ACTION=", 7)) {
416            msg += 7;
417            uevent->action = msg;
418        } else if(!strncmp(msg, "DEVPATH=", 8)) {
419            msg += 8;
420            uevent->path = msg;
421        } else if(!strncmp(msg, "SUBSYSTEM=", 10)) {
422            msg += 10;
423            uevent->subsystem = msg;
424        } else if(!strncmp(msg, "FIRMWARE=", 9)) {
425            msg += 9;
426            uevent->firmware = msg;
427        } else if(!strncmp(msg, "MAJOR=", 6)) {
428            msg += 6;
429            uevent->major = atoi(msg);
430        } else if(!strncmp(msg, "MINOR=", 6)) {
431            msg += 6;
432            uevent->minor = atoi(msg);
433        } else if(!strncmp(msg, "PARTN=", 6)) {
434            msg += 6;
435            uevent->partition_num = atoi(msg);
436        } else if(!strncmp(msg, "PARTNAME=", 9)) {
437            msg += 9;
438            uevent->partition_name = msg;
439        } else if(!strncmp(msg, "DEVNAME=", 8)) {
440            msg += 8;
441            uevent->device_name = msg;
442        }
443
444        /* advance to after the next \0 */
445        while(*msg++)
446            ;
447    }
448
449    if (LOG_UEVENTS) {
450        LOG(INFO) << android::base::StringPrintf("event { '%s', '%s', '%s', '%s', %d, %d }",
451                                                 uevent->action, uevent->path, uevent->subsystem,
452                                                 uevent->firmware, uevent->major, uevent->minor);
453    }
454}
455
456std::vector<std::string> get_character_device_symlinks(uevent* uevent) {
457    platform_node* pdev = find_platform_device(uevent->path);
458    if (!pdev) return {};
459
460    /* skip "/devices/platform/<driver>" */
461    std::string parent = std::string(uevent->path);
462    auto parent_start = parent.find('/', pdev->path_len);
463    if (parent_start == std::string::npos) return {};
464
465    parent.erase(0, parent_start);
466
467    if (!android::base::StartsWith(parent, "/usb")) return {};
468
469    // skip root hub name and device. use device interface
470    // skip 3 slashes, including the first / by starting the search at the 1st character, not 0th.
471    // then extract what comes between the 3rd and 4th slash
472    // e.g. "/usb/usb_device/name/tty2-1:1.0" -> "name"
473
474    std::string::size_type start = 0;
475    start = parent.find('/', start + 1);
476    if (start == std::string::npos) return {};
477
478    start = parent.find('/', start + 1);
479    if (start == std::string::npos) return {};
480
481    auto end = parent.find('/', start + 1);
482    if (end == std::string::npos) return {};
483
484    start++;  // Skip the first '/'
485
486    auto length = end - start;
487    if (length == 0) return {};
488
489    auto name_string = parent.substr(start, length);
490
491    // TODO: remove std::string() when uevent->subsystem is an std::string
492    std::vector<std::string> links;
493    links.emplace_back("/dev/usb/" + std::string(uevent->subsystem) + name_string);
494
495    mkdir("/dev/usb", 0755);
496
497    return links;
498}
499
500// replaces any unacceptable characters with '_', the
501// length of the resulting string is equal to the input string
502void sanitize_partition_name(std::string* string) {
503    const char* accept =
504        "abcdefghijklmnopqrstuvwxyz"
505        "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
506        "0123456789"
507        "_-.";
508
509    if (!string) return;
510
511    std::string::size_type pos = 0;
512    while ((pos = string->find_first_not_of(accept, pos)) != std::string::npos) {
513        (*string)[pos] = '_';
514    }
515}
516
517std::vector<std::string> get_block_device_symlinks(uevent* uevent) {
518    std::string device;
519    struct platform_node* pdev;
520    std::string type;
521
522    pdev = find_platform_device(uevent->path);
523    if (pdev) {
524        device = pdev->name;
525        type = "platform";
526    } else if (find_pci_device_prefix(uevent->path, &device)) {
527        type = "pci";
528    } else if (find_vbd_device_prefix(uevent->path, &device)) {
529        type = "vbd";
530    } else {
531        return {};
532    }
533
534    std::vector<std::string> links;
535
536    LOG(VERBOSE) << "found " << type << " device " << device;
537
538    auto link_path = "/dev/block/" + type + "/" + device;
539
540    if (uevent->partition_name) {
541        std::string partition_name_sanitized(uevent->partition_name);
542        sanitize_partition_name(&partition_name_sanitized);
543        if (partition_name_sanitized != uevent->partition_name) {
544            LOG(VERBOSE) << "Linking partition '" << uevent->partition_name << "' as '"
545                         << partition_name_sanitized << "'";
546        }
547        links.emplace_back(link_path + "/by-name/" + partition_name_sanitized);
548    }
549
550    if (uevent->partition_num >= 0) {
551        links.emplace_back(link_path + "/by-num/p" + std::to_string(uevent->partition_num));
552    }
553
554    // TODO: remove uevent_path when uevent->path is an std::string
555    std::string uevent_path = uevent->path;
556    auto last_slash = uevent_path.rfind('/');
557    links.emplace_back(link_path + "/" + uevent_path.substr(last_slash + 1));
558
559    return links;
560}
561
562static void make_link_init(const char* oldpath, const char* newpath) {
563  const char* slash = strrchr(newpath, '/');
564  if (!slash) return;
565
566  if (mkdir_recursive(dirname(newpath), 0755)) {
567    PLOG(ERROR) << "Failed to create directory " << dirname(newpath);
568  }
569
570  if (symlink(oldpath, newpath) && errno != EEXIST) {
571    PLOG(ERROR) << "Failed to symlink " << oldpath << " to " << newpath;
572  }
573}
574
575static void remove_link(const char* oldpath, const char* newpath) {
576  std::string path;
577  if (android::base::Readlink(newpath, &path) && path == oldpath) unlink(newpath);
578}
579
580static void handle_device(const char* action, const char* devpath, const char* path, int block,
581                          int major, int minor, const std::vector<std::string>& links) {
582    if(!strcmp(action, "add")) {
583        make_device(devpath, path, block, major, minor, links);
584        for (const auto& link : links) {
585            make_link_init(devpath, link.c_str());
586        }
587    }
588
589    if(!strcmp(action, "remove")) {
590        for (const auto& link : links) {
591            remove_link(devpath, link.c_str());
592        }
593        unlink(devpath);
594    }
595}
596
597static void handle_platform_device_event(struct uevent *uevent)
598{
599    const char *path = uevent->path;
600
601    if (!strcmp(uevent->action, "add"))
602        add_platform_device(path);
603    else if (!strcmp(uevent->action, "remove"))
604        remove_platform_device(path);
605}
606
607static const char *parse_device_name(struct uevent *uevent, unsigned int len)
608{
609    const char *name;
610
611    /* if it's not a /dev device, nothing else to do */
612    if((uevent->major < 0) || (uevent->minor < 0))
613        return NULL;
614
615    /* do we have a name? */
616    name = strrchr(uevent->path, '/');
617    if(!name)
618        return NULL;
619    name++;
620
621    /* too-long names would overrun our buffer */
622    if(strlen(name) > len) {
623        LOG(ERROR) << "DEVPATH=" << name << " exceeds " << len << "-character limit on filename; ignoring event";
624        return NULL;
625    }
626
627    return name;
628}
629
630#define DEVPATH_LEN 96
631#define MAX_DEV_NAME 64
632
633static void handle_block_device_event(struct uevent *uevent)
634{
635    const char *base = "/dev/block/";
636    const char *name;
637    char devpath[DEVPATH_LEN];
638
639    name = parse_device_name(uevent, MAX_DEV_NAME);
640    if (!name)
641        return;
642
643    snprintf(devpath, sizeof(devpath), "%s%s", base, name);
644    make_dir(base, 0755);
645
646    std::vector<std::string> links;
647    if (!strncmp(uevent->path, "/devices/", 9))
648        links = get_block_device_symlinks(uevent);
649
650    handle_device(uevent->action, devpath, uevent->path, 1,
651            uevent->major, uevent->minor, links);
652}
653
654static bool assemble_devpath(char *devpath, const char *dirname,
655        const char *devname)
656{
657    int s = snprintf(devpath, DEVPATH_LEN, "%s/%s", dirname, devname);
658    if (s < 0) {
659        PLOG(ERROR) << "failed to assemble device path; ignoring event";
660        return false;
661    } else if (s >= DEVPATH_LEN) {
662        LOG(ERROR) << dirname << "/" << devname
663                   << " exceeds " << DEVPATH_LEN << "-character limit on path; ignoring event";
664        return false;
665    }
666    return true;
667}
668
669static void mkdir_recursive_for_devpath(const char *devpath)
670{
671    char dir[DEVPATH_LEN];
672    char *slash;
673
674    strcpy(dir, devpath);
675    slash = strrchr(dir, '/');
676    *slash = '\0';
677    mkdir_recursive(dir, 0755);
678}
679
680static void handle_generic_device_event(struct uevent *uevent)
681{
682    const char *base;
683    const char *name;
684    char devpath[DEVPATH_LEN] = {0};
685
686    name = parse_device_name(uevent, MAX_DEV_NAME);
687    if (!name)
688        return;
689
690    struct ueventd_subsystem *subsystem =
691            ueventd_subsystem_find_by_name(uevent->subsystem);
692
693    if (subsystem) {
694        const char *devname;
695
696        switch (subsystem->devname_src) {
697        case DEVNAME_UEVENT_DEVNAME:
698            devname = uevent->device_name;
699            break;
700
701        case DEVNAME_UEVENT_DEVPATH:
702            devname = name;
703            break;
704
705        default:
706            LOG(ERROR) << uevent->subsystem << " subsystem's devpath option is not set; ignoring event";
707            return;
708        }
709
710        if (!assemble_devpath(devpath, subsystem->dirname, devname))
711            return;
712        mkdir_recursive_for_devpath(devpath);
713    } else if (!strncmp(uevent->subsystem, "usb", 3)) {
714         if (!strcmp(uevent->subsystem, "usb")) {
715            if (uevent->device_name) {
716                if (!assemble_devpath(devpath, "/dev", uevent->device_name))
717                    return;
718                mkdir_recursive_for_devpath(devpath);
719             }
720             else {
721                 /* This imitates the file system that would be created
722                  * if we were using devfs instead.
723                  * Minors are broken up into groups of 128, starting at "001"
724                  */
725                 int bus_id = uevent->minor / 128 + 1;
726                 int device_id = uevent->minor % 128 + 1;
727                 /* build directories */
728                 make_dir("/dev/bus", 0755);
729                 make_dir("/dev/bus/usb", 0755);
730                 snprintf(devpath, sizeof(devpath), "/dev/bus/usb/%03d", bus_id);
731                 make_dir(devpath, 0755);
732                 snprintf(devpath, sizeof(devpath), "/dev/bus/usb/%03d/%03d", bus_id, device_id);
733             }
734         } else {
735             /* ignore other USB events */
736             return;
737         }
738     } else if (!strncmp(uevent->subsystem, "graphics", 8)) {
739         base = "/dev/graphics/";
740         make_dir(base, 0755);
741     } else if (!strncmp(uevent->subsystem, "drm", 3)) {
742         base = "/dev/dri/";
743         make_dir(base, 0755);
744     } else if (!strncmp(uevent->subsystem, "oncrpc", 6)) {
745         base = "/dev/oncrpc/";
746         make_dir(base, 0755);
747     } else if (!strncmp(uevent->subsystem, "adsp", 4)) {
748         base = "/dev/adsp/";
749         make_dir(base, 0755);
750     } else if (!strncmp(uevent->subsystem, "msm_camera", 10)) {
751         base = "/dev/msm_camera/";
752         make_dir(base, 0755);
753     } else if(!strncmp(uevent->subsystem, "input", 5)) {
754         base = "/dev/input/";
755         make_dir(base, 0755);
756     } else if(!strncmp(uevent->subsystem, "mtd", 3)) {
757         base = "/dev/mtd/";
758         make_dir(base, 0755);
759     } else if(!strncmp(uevent->subsystem, "sound", 5)) {
760         base = "/dev/snd/";
761         make_dir(base, 0755);
762     } else
763         base = "/dev/";
764     auto links = get_character_device_symlinks(uevent);
765
766     if (!devpath[0])
767         snprintf(devpath, sizeof(devpath), "%s%s", base, name);
768
769     handle_device(uevent->action, devpath, uevent->path, 0,
770             uevent->major, uevent->minor, links);
771}
772
773static void handle_device_event(struct uevent *uevent)
774{
775    if (!strcmp(uevent->action,"add") || !strcmp(uevent->action, "change") || !strcmp(uevent->action, "online"))
776        fixup_sys_perms(uevent->path, uevent->subsystem);
777
778    if (!strncmp(uevent->subsystem, "block", 5)) {
779        handle_block_device_event(uevent);
780    } else if (!strncmp(uevent->subsystem, "platform", 8)) {
781        handle_platform_device_event(uevent);
782    } else {
783        handle_generic_device_event(uevent);
784    }
785}
786
787static void load_firmware(uevent* uevent, const std::string& root,
788                          int fw_fd, size_t fw_size,
789                          int loading_fd, int data_fd) {
790    // Start transfer.
791    android::base::WriteFully(loading_fd, "1", 1);
792
793    // Copy the firmware.
794    int rc = sendfile(data_fd, fw_fd, nullptr, fw_size);
795    if (rc == -1) {
796        PLOG(ERROR) << "firmware: sendfile failed { '" << root << "', '" << uevent->firmware << "' }";
797    }
798
799    // Tell the firmware whether to abort or commit.
800    const char* response = (rc != -1) ? "0" : "-1";
801    android::base::WriteFully(loading_fd, response, strlen(response));
802}
803
804static int is_booting() {
805    return access("/dev/.booting", F_OK) == 0;
806}
807
808static void process_firmware_event(uevent* uevent) {
809    int booting = is_booting();
810
811    LOG(INFO) << "firmware: loading '" << uevent->firmware << "' for '" << uevent->path << "'";
812
813    std::string root = android::base::StringPrintf("/sys%s", uevent->path);
814    std::string loading = root + "/loading";
815    std::string data = root + "/data";
816
817    android::base::unique_fd loading_fd(open(loading.c_str(), O_WRONLY|O_CLOEXEC));
818    if (loading_fd == -1) {
819        PLOG(ERROR) << "couldn't open firmware loading fd for " << uevent->firmware;
820        return;
821    }
822
823    android::base::unique_fd data_fd(open(data.c_str(), O_WRONLY|O_CLOEXEC));
824    if (data_fd == -1) {
825        PLOG(ERROR) << "couldn't open firmware data fd for " << uevent->firmware;
826        return;
827    }
828
829try_loading_again:
830    for (size_t i = 0; i < arraysize(firmware_dirs); i++) {
831        std::string file = android::base::StringPrintf("%s/%s", firmware_dirs[i], uevent->firmware);
832        android::base::unique_fd fw_fd(open(file.c_str(), O_RDONLY|O_CLOEXEC));
833        struct stat sb;
834        if (fw_fd != -1 && fstat(fw_fd, &sb) != -1) {
835            load_firmware(uevent, root, fw_fd, sb.st_size, loading_fd, data_fd);
836            return;
837        }
838    }
839
840    if (booting) {
841        // If we're not fully booted, we may be missing
842        // filesystems needed for firmware, wait and retry.
843        std::this_thread::sleep_for(100ms);
844        booting = is_booting();
845        goto try_loading_again;
846    }
847
848    LOG(ERROR) << "firmware: could not find firmware for " << uevent->firmware;
849
850    // Write "-1" as our response to the kernel's firmware request, since we have nothing for it.
851    write(loading_fd, "-1", 2);
852}
853
854static void handle_firmware_event(uevent* uevent) {
855    if (strcmp(uevent->subsystem, "firmware")) return;
856    if (strcmp(uevent->action, "add")) return;
857
858    // Loading the firmware in a child means we can do that in parallel...
859    // (We ignore SIGCHLD rather than wait for our children.)
860    pid_t pid = fork();
861    if (pid == 0) {
862        Timer t;
863        process_firmware_event(uevent);
864        LOG(INFO) << "loading " << uevent->path << " took " << t;
865        _exit(EXIT_SUCCESS);
866    } else if (pid == -1) {
867        PLOG(ERROR) << "could not fork to process firmware event for " << uevent->firmware;
868    }
869}
870
871static bool inline should_stop_coldboot(coldboot_action_t act)
872{
873    return (act == COLDBOOT_STOP || act == COLDBOOT_FINISH);
874}
875
876#define UEVENT_MSG_LEN  2048
877
878static inline coldboot_action_t handle_device_fd_with(
879        std::function<coldboot_action_t(uevent* uevent)> handle_uevent)
880{
881    char msg[UEVENT_MSG_LEN+2];
882    int n;
883    while ((n = uevent_kernel_multicast_recv(device_fd, msg, UEVENT_MSG_LEN)) > 0) {
884        if(n >= UEVENT_MSG_LEN)   /* overflow -- discard */
885            continue;
886
887        msg[n] = '\0';
888        msg[n+1] = '\0';
889
890        struct uevent uevent;
891        parse_event(msg, &uevent);
892        coldboot_action_t act = handle_uevent(&uevent);
893        if (should_stop_coldboot(act))
894            return act;
895    }
896
897    return COLDBOOT_CONTINUE;
898}
899
900coldboot_action_t handle_device_fd(coldboot_callback fn)
901{
902    coldboot_action_t ret = handle_device_fd_with(
903        [&](uevent* uevent) -> coldboot_action_t {
904            if (selinux_status_updated() > 0) {
905                struct selabel_handle *sehandle2;
906                sehandle2 = selinux_android_file_context_handle();
907                if (sehandle2) {
908                    selabel_close(sehandle);
909                    sehandle = sehandle2;
910                }
911            }
912
913            // default is to always create the devices
914            coldboot_action_t act = COLDBOOT_CREATE;
915            if (fn) {
916                act = fn(uevent);
917            }
918
919            if (act == COLDBOOT_CREATE || act == COLDBOOT_STOP) {
920                handle_device_event(uevent);
921                handle_firmware_event(uevent);
922            }
923
924            return act;
925        });
926
927    return ret;
928}
929
930/* Coldboot walks parts of the /sys tree and pokes the uevent files
931** to cause the kernel to regenerate device add events that happened
932** before init's device manager was started
933**
934** We drain any pending events from the netlink socket every time
935** we poke another uevent file to make sure we don't overrun the
936** socket's buffer.
937*/
938
939static coldboot_action_t do_coldboot(DIR *d, coldboot_callback fn)
940{
941    struct dirent *de;
942    int dfd, fd;
943    coldboot_action_t act = COLDBOOT_CONTINUE;
944
945    dfd = dirfd(d);
946
947    fd = openat(dfd, "uevent", O_WRONLY);
948    if (fd >= 0) {
949        write(fd, "add\n", 4);
950        close(fd);
951        act = handle_device_fd(fn);
952        if (should_stop_coldboot(act))
953            return act;
954    }
955
956    while (!should_stop_coldboot(act) && (de = readdir(d))) {
957        DIR *d2;
958
959        if(de->d_type != DT_DIR || de->d_name[0] == '.')
960            continue;
961
962        fd = openat(dfd, de->d_name, O_RDONLY | O_DIRECTORY);
963        if(fd < 0)
964            continue;
965
966        d2 = fdopendir(fd);
967        if(d2 == 0)
968            close(fd);
969        else {
970            act = do_coldboot(d2, fn);
971            closedir(d2);
972        }
973    }
974
975    // default is always to continue looking for uevents
976    return act;
977}
978
979static coldboot_action_t coldboot(const char *path, coldboot_callback fn)
980{
981    std::unique_ptr<DIR, decltype(&closedir)> d(opendir(path), closedir);
982    if (d) {
983        return do_coldboot(d.get(), fn);
984    }
985
986    return COLDBOOT_CONTINUE;
987}
988
989void device_init(const char* path, coldboot_callback fn) {
990    if (!sehandle) {
991        sehandle = selinux_android_file_context_handle();
992    }
993    // open uevent socket and selinux status only if it hasn't been
994    // done before
995    if (device_fd == -1) {
996        /* is 256K enough? udev uses 16MB! */
997        device_fd.reset(uevent_open_socket(256 * 1024, true));
998        if (device_fd == -1) {
999            return;
1000        }
1001        fcntl(device_fd, F_SETFL, O_NONBLOCK);
1002        selinux_status_open(true);
1003    }
1004
1005    if (access(COLDBOOT_DONE, F_OK) == 0) {
1006        LOG(VERBOSE) << "Skipping coldboot, already done!";
1007        return;
1008    }
1009
1010    Timer t;
1011    coldboot_action_t act;
1012    if (!path) {
1013        act = coldboot("/sys/class", fn);
1014        if (!should_stop_coldboot(act)) {
1015            act = coldboot("/sys/block", fn);
1016            if (!should_stop_coldboot(act)) {
1017                act = coldboot("/sys/devices", fn);
1018            }
1019        }
1020    } else {
1021        act = coldboot(path, fn);
1022    }
1023
1024    // If we have a callback, then do as it says. If no, then the default is
1025    // to always create COLDBOOT_DONE file.
1026    if (!fn || (act == COLDBOOT_FINISH)) {
1027        close(open(COLDBOOT_DONE, O_WRONLY|O_CREAT|O_CLOEXEC, 0000));
1028    }
1029
1030    LOG(INFO) << "Coldboot took " << t;
1031}
1032
1033void device_close() {
1034    destroy_platform_devices();
1035    device_fd.reset();
1036    selinux_status_close();
1037}
1038
1039int get_device_fd() {
1040    return device_fd;
1041}
1042