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Merge "Make persistent field in cryptofs support longer values." into lmp-mr1-dev

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automerge: 13c3a90

* commit '13c3a90b586d272b391bd0e2795717db75a4d853':
  Make persistent field in cryptofs support longer values.
This commit is contained in:
Rubin Xu 2014-10-30 18:59:11 +00:00 committed by android-build-merger
commit 84f2515008
3 changed files with 245 additions and 35 deletions
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22
CommandListener.cpp
View file

@ -646,17 +646,33 @@ int CommandListener::CryptfsCmd::runCommand(SocketClient *cli,
SLOGD("cryptfs verifypw {}");
rc = cryptfs_verify_passwd(argv[2]);
} else if (!strcmp(argv[1], "getfield")) {
char valbuf[PROPERTY_VALUE_MAX];
char *valbuf;
int valbuf_len = PROPERTY_VALUE_MAX;
if (argc != 3) {
cli->sendMsg(ResponseCode::CommandSyntaxError, "Usage: cryptfs getfield <fieldname>", false);
return 0;
}
dumpArgs(argc, argv, -1);
rc = cryptfs_getfield(argv[2], valbuf, sizeof(valbuf));
if (rc == 0) {
// Increase the buffer size until it is big enough for the field value stored.
while (1) {
valbuf = (char*)malloc(valbuf_len);
if (valbuf == NULL) {
cli->sendMsg(ResponseCode::OperationFailed, "Failed to allocate memory", false);
return 0;
}
rc = cryptfs_getfield(argv[2], valbuf, valbuf_len);
if (rc != CRYPTO_GETFIELD_ERROR_BUF_TOO_SMALL) {
break;
}
free(valbuf);
valbuf_len *= 2;
}
if (rc == CRYPTO_GETFIELD_OK) {
cli->sendMsg(ResponseCode::CryptfsGetfieldResult, valbuf, false);
}
free(valbuf);
} else if (!strcmp(argv[1], "setfield")) {
if (argc != 4) {
cli->sendMsg(ResponseCode::CommandSyntaxError, "Usage: cryptfs setfield <fieldname> <value>", false);

237
cryptfs.c
View file

@ -41,6 +41,7 @@
#include <linux/kdev_t.h>
#include <fs_mgr.h>
#include <time.h>
#include <math.h>
#include "cryptfs.h"
#define LOG_TAG "Cryptfs"
#include "cutils/log.h"
@ -3303,7 +3304,30 @@ int cryptfs_changepw(int crypt_type, const char *newpw)
return 0;
}
static int persist_get_key(char *fieldname, char *value)
static unsigned int persist_get_max_entries(int encrypted) {
struct crypt_mnt_ftr crypt_ftr;
unsigned int dsize;
unsigned int max_persistent_entries;
/* If encrypted, use the values from the crypt_ftr, otherwise
* use the values for the current spec.
*/
if (encrypted) {
if (get_crypt_ftr_and_key(&crypt_ftr)) {
return -1;
}
dsize = crypt_ftr.persist_data_size;
} else {
dsize = CRYPT_PERSIST_DATA_SIZE;
}
max_persistent_entries = (dsize - sizeof(struct crypt_persist_data)) /
sizeof(struct crypt_persist_entry);
return max_persistent_entries;
}
static int persist_get_key(const char *fieldname, char *value)
{
unsigned int i;
@ -3321,31 +3345,17 @@ static int persist_get_key(char *fieldname, char *value)
return -1;
}
static int persist_set_key(char *fieldname, char *value, int encrypted)
static int persist_set_key(const char *fieldname, const char *value, int encrypted)
{
unsigned int i;
unsigned int num;
struct crypt_mnt_ftr crypt_ftr;
unsigned int max_persistent_entries;
unsigned int dsize;
if (persist_data == NULL) {
return -1;
}
/* If encrypted, use the values from the crypt_ftr, otherwise
* use the values for the current spec.
*/
if (encrypted) {
if(get_crypt_ftr_and_key(&crypt_ftr)) {
return -1;
}
dsize = crypt_ftr.persist_data_size;
} else {
dsize = CRYPT_PERSIST_DATA_SIZE;
}
max_persistent_entries = (dsize - sizeof(struct crypt_persist_data)) /
sizeof(struct crypt_persist_entry);
max_persistent_entries = persist_get_max_entries(encrypted);
num = persist_data->persist_valid_entries;
@ -3370,15 +3380,109 @@ static int persist_set_key(char *fieldname, char *value, int encrypted)
return -1;
}
/**
* Test if key is part of the multi-entry (field, index) sequence. Return non-zero if key is in the
* sequence and its index is greater than or equal to index. Return 0 otherwise.
*/
static int match_multi_entry(const char *key, const char *field, unsigned index) {
unsigned int i;
unsigned int field_len;
unsigned int key_index;
field_len = strlen(field);
if (index == 0) {
// The first key in a multi-entry field is just the filedname itself.
if (!strcmp(key, field)) {
return 1;
}
}
// Match key against "%s_%d" % (field, index)
if (strlen(key) < field_len + 1 + 1) {
// Need at least a '_' and a digit.
return 0;
}
if (strncmp(key, field, field_len)) {
// If the key does not begin with field, it's not a match.
return 0;
}
if (1 != sscanf(&key[field_len],"_%d", &key_index)) {
return 0;
}
return key_index >= index;
}
/*
* Delete entry/entries from persist_data. If the entries are part of a multi-segment field, all
* remaining entries starting from index will be deleted.
* returns PERSIST_DEL_KEY_OK if deletion succeeds,
* PERSIST_DEL_KEY_ERROR_NO_FIELD if the field does not exist,
* and PERSIST_DEL_KEY_ERROR_OTHER if error occurs.
*
*/
static int persist_del_keys(const char *fieldname, unsigned index)
{
unsigned int i;
unsigned int j;
unsigned int num;
if (persist_data == NULL) {
return PERSIST_DEL_KEY_ERROR_OTHER;
}
num = persist_data->persist_valid_entries;
j = 0; // points to the end of non-deleted entries.
// Filter out to-be-deleted entries in place.
for (i = 0; i < num; i++) {
if (!match_multi_entry(persist_data->persist_entry[i].key, fieldname, index)) {
persist_data->persist_entry[j] = persist_data->persist_entry[i];
j++;
}
}
if (j < num) {
persist_data->persist_valid_entries = j;
// Zeroise the remaining entries
memset(&persist_data->persist_entry[j], 0, (num - j) * sizeof(struct crypt_persist_entry));
return PERSIST_DEL_KEY_OK;
} else {
// Did not find an entry matching the given fieldname
return PERSIST_DEL_KEY_ERROR_NO_FIELD;
}
}
static int persist_count_keys(const char *fieldname)
{
unsigned int i;
unsigned int count;
if (persist_data == NULL) {
return -1;
}
count = 0;
for (i = 0; i < persist_data->persist_valid_entries; i++) {
if (match_multi_entry(persist_data->persist_entry[i].key, fieldname, 0)) {
count++;
}
}
return count;
}
/* Return the value of the specified field. */
int cryptfs_getfield(char *fieldname, char *value, int len)
int cryptfs_getfield(const char *fieldname, char *value, int len)
{
char temp_value[PROPERTY_VALUE_MAX];
char real_blkdev[MAXPATHLEN];
/* 0 is success, 1 is not encrypted,
* -1 is value not set, -2 is any other error
/* CRYPTO_GETFIELD_OK is success,
* CRYPTO_GETFIELD_ERROR_NO_FIELD is value not set,
* CRYPTO_GETFIELD_ERROR_BUF_TOO_SMALL is buffer (as given by len) too small,
* CRYPTO_GETFIELD_ERROR_OTHER is any other error
*/
int rc = -2;
int rc = CRYPTO_GETFIELD_ERROR_OTHER;
int i;
char temp_field[PROPERTY_KEY_MAX];
if (persist_data == NULL) {
load_persistent_data();
@ -3388,13 +3492,40 @@ int cryptfs_getfield(char *fieldname, char *value, int len)
}
}
// Read value from persistent entries. If the original value is split into multiple entries,
// stitch them back together.
if (!persist_get_key(fieldname, temp_value)) {
/* We found it, copy it to the caller's buffer and return */
strlcpy(value, temp_value, len);
rc = 0;
// We found it, copy it to the caller's buffer and keep going until all entries are read.
if (strlcpy(value, temp_value, len) >= (unsigned) len) {
// value too small
rc = CRYPTO_GETFIELD_ERROR_BUF_TOO_SMALL;
goto out;
}
rc = CRYPTO_GETFIELD_OK;
for (i = 1; /* break explicitly */; i++) {
if (snprintf(temp_field, sizeof(temp_field), "%s_%d", fieldname, i) >=
(int) sizeof(temp_field)) {
// If the fieldname is very long, we stop as soon as it begins to overflow the
// maximum field length. At this point we have in fact fully read out the original
// value because cryptfs_setfield would not allow fields with longer names to be
// written in the first place.
break;
}
if (!persist_get_key(temp_field, temp_value)) {
if (strlcat(value, temp_value, len) >= (unsigned)len) {
// value too small.
rc = CRYPTO_GETFIELD_ERROR_BUF_TOO_SMALL;
goto out;
}
} else {
// Exhaust all entries.
break;
}
}
} else {
/* Sadness, it's not there. Return the error */
rc = -1;
rc = CRYPTO_GETFIELD_ERROR_NO_FIELD;
}
out:
@ -3402,15 +3533,19 @@ out:
}
/* Set the value of the specified field. */
int cryptfs_setfield(char *fieldname, char *value)
int cryptfs_setfield(const char *fieldname, const char *value)
{
struct crypt_persist_data stored_pdata;
struct crypt_persist_data *pdata_p;
struct crypt_mnt_ftr crypt_ftr;
char encrypted_state[PROPERTY_VALUE_MAX];
/* 0 is success, -1 is an error */
int rc = -1;
/* 0 is success, negative values are error */
int rc = CRYPTO_SETFIELD_ERROR_OTHER;
int encrypted = 0;
unsigned int field_id;
char temp_field[PROPERTY_KEY_MAX];
unsigned int num_entries;
unsigned int max_keylen;
if (persist_data == NULL) {
load_persistent_data();
@ -3425,10 +3560,52 @@ int cryptfs_setfield(char *fieldname, char *value)
encrypted = 1;
}
if (persist_set_key(fieldname, value, encrypted)) {
// Compute the number of entries required to store value, each entry can store up to
// (PROPERTY_VALUE_MAX - 1) chars
if (strlen(value) == 0) {
// Empty value also needs one entry to store.
num_entries = 1;
} else {
num_entries = (strlen(value) + (PROPERTY_VALUE_MAX - 1) - 1) / (PROPERTY_VALUE_MAX - 1);
}
max_keylen = strlen(fieldname);
if (num_entries > 1) {
// Need an extra "_%d" suffix.
max_keylen += 1 + log10(num_entries);
}
if (max_keylen > PROPERTY_KEY_MAX - 1) {
rc = CRYPTO_SETFIELD_ERROR_FIELD_TOO_LONG;
goto out;
}
// Make sure we have enough space to write the new value
if (persist_data->persist_valid_entries + num_entries - persist_count_keys(fieldname) >
persist_get_max_entries(encrypted)) {
rc = CRYPTO_SETFIELD_ERROR_VALUE_TOO_LONG;
goto out;
}
// Now that we know persist_data has enough space for value, let's delete the old field first
// to make up space.
persist_del_keys(fieldname, 0);
if (persist_set_key(fieldname, value, encrypted)) {
// fail to set key, should not happen as we have already checked the available space
SLOGE("persist_set_key() error during setfield()");
goto out;
}
for (field_id = 1; field_id < num_entries; field_id++) {
snprintf(temp_field, sizeof(temp_field), "%s_%d", fieldname, field_id);
if (persist_set_key(temp_field, value + field_id * (PROPERTY_VALUE_MAX - 1), encrypted)) {
// fail to set key, should not happen as we have already checked the available space.
SLOGE("persist_set_key() error during setfield()");
goto out;
}
}
/* If we are running encrypted, save the persistent data now */
if (encrypted) {
if (save_persistent_data()) {
@ -3437,7 +3614,7 @@ int cryptfs_setfield(char *fieldname, char *value)
}
}
rc = 0;
rc = CRYPTO_SETFIELD_OK;
out:
return rc;

21
cryptfs.h
View file

@ -201,6 +201,23 @@ struct volume_info {
#define ENABLE_INPLACE_ERR_OTHER -1
#define ENABLE_INPLACE_ERR_DEV -2 /* crypto_blkdev issue */
/* Return values for cryptfs_getfield */
#define CRYPTO_GETFIELD_OK 0
#define CRYPTO_GETFIELD_ERROR_NO_FIELD -1
#define CRYPTO_GETFIELD_ERROR_OTHER -2
#define CRYPTO_GETFIELD_ERROR_BUF_TOO_SMALL -3
/* Return values for cryptfs_setfield */
#define CRYPTO_SETFIELD_OK 0
#define CRYPTO_SETFIELD_ERROR_OTHER -1
#define CRYPTO_SETFIELD_ERROR_FIELD_TOO_LONG -2
#define CRYPTO_SETFIELD_ERROR_VALUE_TOO_LONG -3
/* Return values for persist_del_key */
#define PERSIST_DEL_KEY_OK 0
#define PERSIST_DEL_KEY_ERROR_OTHER -1
#define PERSIST_DEL_KEY_ERROR_NO_FIELD -2
#ifdef __cplusplus
extern "C" {
#endif
@ -219,8 +236,8 @@ extern "C" {
char *crypto_dev_path, unsigned int max_pathlen,
int *new_major, int *new_minor);
int cryptfs_revert_volume(const char *label);
int cryptfs_getfield(char *fieldname, char *value, int len);
int cryptfs_setfield(char *fieldname, char *value);
int cryptfs_getfield(const char *fieldname, char *value, int len);
int cryptfs_setfield(const char *fieldname, const char *value);
int cryptfs_mount_default_encrypted(void);
int cryptfs_get_password_type(void);
char* cryptfs_get_password(void);