Fixed MTP to work with TWRP

fs/sdcardfs/packagelist.c

@@ -0,0 +1,359 @@
+/*
+ * fs/sdcardfs/packagelist.c
+ *
+ * Copyright (c) 2013 Samsung Electronics Co. Ltd
+ *   Authors: Daeho Jeong, Woojoong Lee, Seunghwan Hyun, 
+ *               Sunghwan Yun, Sungjong Seo
+ *                      
+ * This program has been developed as a stackable file system based on
+ * the WrapFS which written by 
+ *
+ * Copyright (c) 1998-2011 Erez Zadok
+ * Copyright (c) 2009     Shrikar Archak
+ * Copyright (c) 2003-2011 Stony Brook University
+ * Copyright (c) 2003-2011 The Research Foundation of SUNY
+ *
+ * This file is dual licensed.  It may be redistributed and/or modified
+ * under the terms of the Apache 2.0 License OR version 2 of the GNU
+ * General Public License.
+ */
+
+#include "sdcardfs.h"
+#include <linux/hashtable.h>
+#include <linux/syscalls.h>
+#include <linux/kthread.h>
+#include <linux/inotify.h>
+#include <linux/delay.h>
+
+#define STRING_BUF_SIZE		(512)
+
+struct hashtable_entry {
+        struct hlist_node hlist;
+        void *key;
+	int value;
+};
+
+struct packagelist_data {
+	DECLARE_HASHTABLE(package_to_appid,8);
+	struct mutex hashtable_lock;
+	struct task_struct *thread_id;
+	char read_buf[STRING_BUF_SIZE];
+	char event_buf[STRING_BUF_SIZE];
+	char app_name_buf[STRING_BUF_SIZE];
+	char gids_buf[STRING_BUF_SIZE];
+};
+
+static struct kmem_cache *hashtable_entry_cachep;
+
+/* Path to system-provided mapping of package name to appIds */
+static const char* const kpackageslist_file = "/data/system/packages.list";
+/* Supplementary groups to execute with */
+static const gid_t kgroups[1] = { AID_PACKAGE_INFO };
+
+static unsigned int str_hash(void *key) {
+	int i;
+	unsigned int h = strlen(key);
+	char *data = (char *)key;
+
+	for (i = 0; i < strlen(key); i++) {
+		h = h * 31 + *data;
+		data++;
+	}
+	return h;
+}
+
+appid_t get_appid(void *pkgl_id, const char *app_name)
+{
+	struct packagelist_data *pkgl_dat = (struct packagelist_data *)pkgl_id;
+	struct hashtable_entry *hash_cur;
+	unsigned int hash = str_hash((void *)app_name);
+	appid_t ret_id;
+
+	//printk(KERN_INFO "sdcardfs: %s: %s, %u\n", __func__, (char *)app_name, hash);
+	mutex_lock(&pkgl_dat->hashtable_lock);
+	hash_for_each_possible(pkgl_dat->package_to_appid, hash_cur, hlist, hash) {
+		//printk(KERN_INFO "sdcardfs: %s: %s\n", __func__, (char *)hash_cur->key);
+		if (!strcasecmp(app_name, hash_cur->key)) {
+			ret_id = (appid_t)hash_cur->value;
+			mutex_unlock(&pkgl_dat->hashtable_lock);
+			//printk(KERN_INFO "=> app_id: %d\n", (int)ret_id);
+			return ret_id;
+		}
+	}
+	mutex_unlock(&pkgl_dat->hashtable_lock);
+	//printk(KERN_INFO "=> app_id: %d\n", 0);
+	return 0;
+}
+
+/* Kernel has already enforced everything we returned through
+ * derive_permissions_locked(), so this is used to lock down access
+ * even further, such as enforcing that apps hold sdcard_rw. */
+int check_caller_access_to_name(struct inode *parent_node, const char* name) {
+	/* Always block security-sensitive files at root */
+	if (parent_node && SDCARDFS_I(parent_node)->perm == PERM_ROOT) {
+		if (!strcasecmp(name, "autorun.inf")
+			|| !strcasecmp(name, ".android_secure")
+			|| !strcasecmp(name, "android_secure")) {
+			return 0;
+		}
+	}
+
+	/* Root always has access; access for any other UIDs should always
+	 * be controlled through packages.list. */
+	if (uid_eq(current_fsuid(), make_kuid(current_user_ns(), 0))) {
+		return 1;
+	}
+
+	/* No extra permissions to enforce */
+	return 1;
+}
+
+/* This function is used when file opening. The open flags must be
+ * checked before calling check_caller_access_to_name() */  
+int open_flags_to_access_mode(int open_flags) {
+	if((open_flags & O_ACCMODE) == O_RDONLY) {
+		return 0; /* R_OK */
+	} else if ((open_flags & O_ACCMODE) == O_WRONLY) {
+		return 1; /* W_OK */
+	} else {
+		/* Probably O_RDRW, but treat as default to be safe */
+		return 1; /* R_OK | W_OK */
+	}
+}
+
+static int insert_str_to_int(struct packagelist_data *pkgl_dat, void *key, int value) {
+	struct hashtable_entry *hash_cur;
+	struct hashtable_entry *new_entry;
+	unsigned int hash = str_hash(key);
+
+	//printk(KERN_INFO "sdcardfs: %s: %s: %d, %u\n", __func__, (char *)key, value, hash);
+	hash_for_each_possible(pkgl_dat->package_to_appid, hash_cur, hlist, hash) {
+		if (!strcasecmp(key, hash_cur->key)) {
+			hash_cur->value = value;
+			return 0;
+		}
+	}
+	new_entry = kmem_cache_alloc(hashtable_entry_cachep, GFP_KERNEL);
+	if (!new_entry)
+		return -ENOMEM;
+	new_entry->key = kstrdup(key, GFP_KERNEL);
+	new_entry->value = value;
+	hash_add(pkgl_dat->package_to_appid, &new_entry->hlist, hash);
+	return 0;
+}
+
+static void remove_str_to_int(struct hashtable_entry *h_entry) {
+	//printk(KERN_INFO "sdcardfs: %s: %s: %d\n", __func__, (char *)h_entry->key, h_entry->value);
+	kfree(h_entry->key);
+	kmem_cache_free(hashtable_entry_cachep, h_entry);
+}
+
+/*static void remove_int_to_null(struct hashtable_entry *h_entry) {
+	//printk(KERN_INFO "sdcardfs: %s: %d: %d\n", __func__, (int)h_entry->key, h_entry->value);
+	kmem_cache_free(hashtable_entry_cachep, h_entry);
+}*/
+
+static void remove_all_hashentrys(struct packagelist_data *pkgl_dat)
+{
+	struct hashtable_entry *hash_cur;
+	struct hlist_node *h_t;
+	int i;
+
+	hash_for_each_safe(pkgl_dat->package_to_appid, i, h_t, hash_cur, hlist)
+		remove_str_to_int(hash_cur);
+
+	hash_init(pkgl_dat->package_to_appid);
+}
+
+static int read_package_list(struct packagelist_data *pkgl_dat) {
+	int ret;
+	int fd;
+	int read_amount;
+
+	printk(KERN_INFO "sdcardfs: read_package_list\n");
+
+	mutex_lock(&pkgl_dat->hashtable_lock);
+
+	remove_all_hashentrys(pkgl_dat);
+
+	fd = sys_open(kpackageslist_file, O_RDONLY, 0);
+	if (fd < 0) {
+		printk(KERN_ERR "sdcardfs: failed to open package list\n");
+		mutex_unlock(&pkgl_dat->hashtable_lock);
+		return fd;
+	}
+
+	while ((read_amount = sys_read(fd, pkgl_dat->read_buf,
+					sizeof(pkgl_dat->read_buf))) > 0) {
+		int appid;
+		int one_line_len = 0;
+		int additional_read;
+	
+		while (one_line_len < read_amount) {
+			if (pkgl_dat->read_buf[one_line_len] == '\n') {
+				one_line_len++;
+				break;
+			}
+			one_line_len++;
+		}
+		additional_read = read_amount - one_line_len;
+		if (additional_read > 0)
+			sys_lseek(fd, -additional_read, SEEK_CUR);	
+
+		if (sscanf(pkgl_dat->read_buf, "%s %d %*d %*s %*s %s",
+				pkgl_dat->app_name_buf, &appid,
+				pkgl_dat->gids_buf) == 3) {
+			ret = insert_str_to_int(pkgl_dat, pkgl_dat->app_name_buf, appid);
+			if (ret) {
+				sys_close(fd);
+				mutex_unlock(&pkgl_dat->hashtable_lock);
+				return ret;
+			}
+		}
+	}
+
+	sys_close(fd);
+	mutex_unlock(&pkgl_dat->hashtable_lock);
+	return 0;
+}
+
+static int packagelist_reader(void *thread_data)
+{
+	struct packagelist_data *pkgl_dat = (struct packagelist_data *)thread_data;
+	struct inotify_event *event;
+	bool active = false;
+	int event_pos;
+	int event_size;
+	int res = 0;
+	int nfd;
+
+	allow_signal(SIGINT);
+
+	nfd = sys_inotify_init();
+	if (nfd < 0) {
+		printk(KERN_ERR "sdcardfs: inotify_init failed: %d\n", nfd);
+		return nfd;
+	}
+
+	while (!kthread_should_stop()) {
+		if (signal_pending(current)) {
+			msleep(100);
+			continue;
+		}
+
+		if (!active) {
+			res = sys_inotify_add_watch(nfd, kpackageslist_file, IN_DELETE_SELF);
+			if (res < 0) {
+				if (res == -ENOENT || res == -EACCES) {
+				/* Framework may not have created yet, sleep and retry */
+					printk(KERN_ERR "sdcardfs: missing packages.list; retrying\n");
+					ssleep(2);
+					printk(KERN_ERR "sdcardfs: missing packages.list_end; retrying\n");
+					continue;
+				} else {
+					printk(KERN_ERR "sdcardfs: inotify_add_watch failed: %d\n", res);
+					goto interruptable_sleep;
+				}
+			}
+			/* Watch above will tell us about any future changes, so
+			 * read the current state. */
+			res = read_package_list(pkgl_dat);
+			if (res) {
+				printk(KERN_ERR "sdcardfs: read_package_list failed: %d\n", res);
+				goto interruptable_sleep;
+			}
+			active = true;
+		}
+
+		event_pos = 0;
+		res = sys_read(nfd, pkgl_dat->event_buf, sizeof(pkgl_dat->event_buf));
+		if (res < (int) sizeof(*event)) {
+			if (res == -EINTR)
+				continue;
+			printk(KERN_ERR "sdcardfs: failed to read inotify event: %d\n", res);
+			goto interruptable_sleep;
+		}
+
+		while (res >= (int) sizeof(*event)) {
+			event = (struct inotify_event *) (pkgl_dat->event_buf + event_pos);
+
+			printk(KERN_INFO "sdcardfs: inotify event: %08x\n", event->mask);
+			if ((event->mask & IN_IGNORED) == IN_IGNORED) {
+				/* Previously watched file was deleted, probably due to move
+				 * that swapped in new data; re-arm the watch and read. */
+				active = false;
+			}
+
+			event_size = sizeof(*event) + event->len;
+			res -= event_size;
+			event_pos += event_size;
+		}
+		continue;
+
+interruptable_sleep:
+		set_current_state(TASK_INTERRUPTIBLE);
+		schedule();
+	}
+	flush_signals(current);
+	sys_close(nfd);
+	return res;
+}
+
+void * packagelist_create(void)
+{
+	struct packagelist_data *pkgl_dat;
+	struct task_struct *packagelist_thread;
+
+	pkgl_dat = kmalloc(sizeof(*pkgl_dat), GFP_KERNEL | __GFP_ZERO);
+	if (!pkgl_dat) {
+		printk(KERN_ERR "sdcardfs: creating kthread failed\n");
+		return ERR_PTR(-ENOMEM);
+	}
+
+	mutex_init(&pkgl_dat->hashtable_lock);
+	hash_init(pkgl_dat->package_to_appid);
+
+	packagelist_thread = kthread_run(packagelist_reader, (void *)pkgl_dat, "pkgld");
+	if (IS_ERR(packagelist_thread)) {
+		printk(KERN_ERR "sdcardfs: creating kthread failed\n");
+		kfree(pkgl_dat);
+		return packagelist_thread;
+	}
+	pkgl_dat->thread_id = packagelist_thread;	
+
+	printk(KERN_INFO "sdcardfs: created packagelist pkgld/%d\n",
+				(int)pkgl_dat->thread_id->pid);
+
+	return (void *)pkgl_dat;
+}
+
+void packagelist_destroy(void *pkgl_id)
+{
+	struct packagelist_data *pkgl_dat = (struct packagelist_data *)pkgl_id;
+	pid_t pkgl_pid = pkgl_dat->thread_id->pid;	
+
+	force_sig_info(SIGINT, SEND_SIG_PRIV, pkgl_dat->thread_id);
+	kthread_stop(pkgl_dat->thread_id);
+	remove_all_hashentrys(pkgl_dat);
+	printk(KERN_INFO "sdcardfs: destroyed packagelist pkgld/%d\n", (int)pkgl_pid);
+	kfree(pkgl_dat);
+}
+
+int packagelist_init(void)
+{
+	hashtable_entry_cachep =
+		kmem_cache_create("packagelist_hashtable_entry",
+					sizeof(struct hashtable_entry), 0, 0, NULL);
+	if (!hashtable_entry_cachep) {
+		printk(KERN_ERR "sdcardfs: failed creating pkgl_hashtable entry slab cache\n");
+		return -ENOMEM;
+	}
+
+        return 0;
+}
+
+void packagelist_exit(void)
+{
+	if (hashtable_entry_cachep)
+		kmem_cache_destroy(hashtable_entry_cachep);
+}