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Bugfix: Possible Out of Bounds Write in StreamNameIO and BlockNameIO #15

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Issue #15, the encodeName functions fail to verify buffer length can
  store encoded filenames
For good measure and interface consistency, also check decodeName fnc
This commit is contained in:
Charles Munson 2016-03-23 14:07:52 +01:00
parent da03864538
commit a0e02cb3ea
8 changed files with 61 additions and 35 deletions
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8
encfs/BlockNameIO.cpp
View File

@ -135,14 +135,17 @@ int BlockNameIO::maxDecodedNameLen(int encodedNameLen) const {
}
int BlockNameIO::encodeName(const char *plaintextName, int length, uint64_t *iv,
char *encodedName) const {
char *encodedName, int bufferLength) const {
// copy the data into the encoding buffer..
rAssert(length <= (bufferLength - 2));
memcpy(encodedName + 2, plaintextName, length);
// Pad encryption buffer to block boundary..
int padding = _bs - length % _bs;
if (padding == 0) padding = _bs; // padding a full extra block!
rAssert(padding <= (bufferLength - length - 2));
memset(encodedName + length + 2, (unsigned char)padding, padding);
// store the IV before it is modified by the MAC call.
@ -182,7 +185,7 @@ int BlockNameIO::encodeName(const char *plaintextName, int length, uint64_t *iv,
}
int BlockNameIO::decodeName(const char *encodedName, int length, uint64_t *iv,
char *plaintextName) const {
char *plaintextName, int bufferLength) const {
int decLen256 =
_caseSensitive ? B32ToB256Bytes(length) : B64ToB256Bytes(length);
int decodedStreamLen = decLen256 - 2;
@ -225,6 +228,7 @@ int BlockNameIO::decodeName(const char *encodedName, int length, uint64_t *iv,
}
// copy out the result..
rAssert(finalSize < bufferLength);
memcpy(plaintextName, tmpBuf + 2, finalSize);
plaintextName[finalSize] = '\0';

4
encfs/BlockNameIO.h
View File

@ -55,9 +55,9 @@ class BlockNameIO : public NameIO {
protected:
virtual int encodeName(const char *plaintextName, int length, uint64_t *iv,
char *encodedName) const;
char *encodedName, int bufferLength) const;
virtual int decodeName(const char *encodedName, int length, uint64_t *iv,
char *plaintextName) const;
char *plaintextName, int bufferLength) const;
private:
int _interface;

25
encfs/NameIO.cpp
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@ -142,7 +142,7 @@ bool NameIO::getReverseEncryption() const { return reverseEncryption; }
std::string NameIO::recodePath(const char *path,
int (NameIO::*_length)(int) const,
int (NameIO::*_code)(const char *, int,
uint64_t *, char *) const,
uint64_t *, char *, int) const,
uint64_t *iv) const {
string output;
@ -166,11 +166,12 @@ std::string NameIO::recodePath(const char *path,
// figure out buffer sizes
int approxLen = (this->*_length)(len);
if (approxLen <= 0) throw ERROR("Filename too small to decode");
int bufSize = 0;
BUFFER_INIT(codeBuf, 32, (unsigned int)approxLen + 1)
BUFFER_INIT_S(codeBuf, 32, (unsigned int)approxLen + 1, bufSize)
// code the name
int codedLen = (this->*_code)(path, len, iv, codeBuf);
int codedLen = (this->*_code)(path, len, iv, codeBuf, bufSize);
rAssert(codedLen <= approxLen);
rAssert(codeBuf[codedLen] == '\0');
path += len;
@ -217,21 +218,22 @@ std::string NameIO::decodePath(const char *path, uint64_t *iv) const {
return getReverseEncryption() ? _encodePath(path, iv) : _decodePath(path, iv);
}
int NameIO::encodeName(const char *input, int length, char *output) const {
return encodeName(input, length, (uint64_t *)0, output);
int NameIO::encodeName(const char *input, int length, char *output, int bufferLength) const {
return encodeName(input, length, (uint64_t *)0, output, bufferLength);
}
int NameIO::decodeName(const char *input, int length, char *output) const {
return decodeName(input, length, (uint64_t *)0, output);
int NameIO::decodeName(const char *input, int length, char *output, int bufferLength) const {
return decodeName(input, length, (uint64_t *)0, output, bufferLength);
}
std::string NameIO::_encodeName(const char *plaintextName, int length) const {
int approxLen = maxEncodedNameLen(length);
int bufSize = 0;
BUFFER_INIT(codeBuf, 32, (unsigned int)approxLen + 1)
BUFFER_INIT_S(codeBuf, 32, (unsigned int)approxLen + 1, bufSize)
// code the name
int codedLen = encodeName(plaintextName, length, 0, codeBuf);
int codedLen = encodeName(plaintextName, length, 0, codeBuf, bufSize);
rAssert(codedLen <= approxLen);
rAssert(codeBuf[codedLen] == '\0');
@ -245,11 +247,12 @@ std::string NameIO::_encodeName(const char *plaintextName, int length) const {
std::string NameIO::_decodeName(const char *encodedName, int length) const {
int approxLen = maxDecodedNameLen(length);
int bufSize = 0;
BUFFER_INIT(codeBuf, 32, (unsigned int)approxLen + 1)
BUFFER_INIT_S(codeBuf, 32, (unsigned int)approxLen + 1, bufSize)
// code the name
int codedLen = decodeName(encodedName, length, 0, codeBuf);
int codedLen = decodeName(encodedName, length, 0, codeBuf, bufSize);
rAssert(codedLen <= approxLen);
rAssert(codeBuf[codedLen] == '\0');

20
encfs/NameIO.h
View File

@ -83,19 +83,19 @@ class NameIO {
protected:
virtual int encodeName(const char *plaintextName, int length,
char *encodedName) const;
char *encodedName, int bufferLength) const;
virtual int decodeName(const char *encodedName, int length,
char *plaintextName) const;
char *plaintextName, int bufferLength) const;
virtual int encodeName(const char *plaintextName, int length, uint64_t *iv,
char *encodedName) const = 0;
char *encodedName, int bufferLength) const = 0;
virtual int decodeName(const char *encodedName, int length, uint64_t *iv,
char *plaintextName) const = 0;
char *plaintextName, int bufferLength) const = 0;
private:
std::string recodePath(const char *path, int (NameIO::*codingLen)(int) const,
int (NameIO::*codingFunc)(const char *, int,
uint64_t *, char *) const,
uint64_t *, char *, int) const,
uint64_t *iv) const;
std::string _encodePath(const char *plaintextPath, uint64_t *iv) const;
@ -120,6 +120,16 @@ class NameIO {
if (sizeof(Name##_Raw) < Size) Name = new char[Size]; \
memset(Name, 0, Size);
#define BUFFER_INIT_S(Name, OptimizedSize, Size, BufSize) \
char Name##_Raw[OptimizedSize]; \
BufSize = sizeof(Name##_Raw); \
char *Name = Name##_Raw; \
if (sizeof(Name##_Raw) < Size) { \
Name = new char[Size]; \
BufSize = Size; \
} \
memset(Name, 0, Size);
#define BUFFER_RESET(Name) \
do { \
if (Name != Name##_Raw) { \

8
encfs/NullNameIO.cpp
View File

@ -56,16 +56,20 @@ int NullNameIO::maxDecodedNameLen(int encodedNameLen) const {
}
int NullNameIO::encodeName(const char *plaintextName, int length, uint64_t *iv,
char *encodedName) const {
char *encodedName, int bufferLength) const {
(void)iv;
rAssert(length <= bufferLength);
memcpy(encodedName, plaintextName, length);
return length;
}
int NullNameIO::decodeName(const char *encodedName, int length, uint64_t *iv,
char *plaintextName) const {
char *plaintextName, int bufferLength) const {
(void)iv;
rAssert(length <= bufferLength);
memcpy(plaintextName, encodedName, length);
return length;

6
encfs/NullNameIO.h
View File

@ -23,6 +23,8 @@
#include <stdint.h>
#include "rlog/Error.h"
#include "rlog/rlog.h"
#include "Interface.h"
#include "NameIO.h"
@ -44,9 +46,9 @@ class NullNameIO : public NameIO {
protected:
virtual int encodeName(const char *plaintextName, int length, uint64_t *iv,
char *encodedName) const;
char *encodedName, int bufferLength) const;
virtual int decodeName(const char *encodedName, int length, uint64_t *iv,
char *plaintextName) const;
char *plaintextName, int bufferLength) const;
private:
};

7
encfs/StreamNameIO.cpp
View File

@ -90,7 +90,7 @@ int StreamNameIO::maxDecodedNameLen(int encodedStreamLen) const {
}
int StreamNameIO::encodeName(const char *plaintextName, int length,
uint64_t *iv, char *encodedName) const {
uint64_t *iv, char *encodedName, int bufferLength) const {
uint64_t tmpIV = 0;
if (iv && _interface >= 2) tmpIV = *iv;
@ -104,11 +104,13 @@ int StreamNameIO::encodeName(const char *plaintextName, int length,
encodedName[0] = (mac >> 8) & 0xff;
encodedName[1] = (mac)&0xff;
encodeBegin = (unsigned char *)encodedName + 2;
rAssert(length <= (bufferLength - 2));
} else {
// encfs 0.x stored checksums at the end.
encodedName[length] = (mac >> 8) & 0xff;
encodedName[length + 1] = (mac)&0xff;
encodeBegin = (unsigned char *)encodedName;
rAssert(length <= bufferLength);
}
// stream encode the plaintext bytes
@ -126,10 +128,11 @@ int StreamNameIO::encodeName(const char *plaintextName, int length,
}
int StreamNameIO::decodeName(const char *encodedName, int length, uint64_t *iv,
char *plaintextName) const {
char *plaintextName, int bufferLength) const {
rAssert(length > 2);
int decLen256 = B64ToB256Bytes(length);
int decodedStreamLen = decLen256 - 2;
rAssert(decodedStreamLen <= bufferLength);
if (decodedStreamLen <= 0) throw ERROR("Filename too small to decode");

4
encfs/StreamNameIO.h
View File

@ -48,9 +48,9 @@ class StreamNameIO : public NameIO {
protected:
virtual int encodeName(const char *plaintextName, int length, uint64_t *iv,
char *encodedName) const;
char *encodedName, int bufferLength) const;
virtual int decodeName(const char *encodedName, int length, uint64_t *iv,
char *plaintextName) const;
char *plaintextName, int bufferLength) const;
private:
int _interface;