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Defer object/value decryption to after the object is loaded (Issue #42)

This commit is contained in:
Michael R Sweet 2023-12-14 16:02:26 -05:00
parent 5d760e7315
commit 7330cc35ba
No known key found for this signature in database
GPG Key ID: BE67C75EC81F3244
5 changed files with 233 additions and 96 deletions
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24
pdfio-array.c
View File

@ -327,6 +327,30 @@ pdfioArrayCreate(pdfio_file_t *pdf) // I - PDF file
}
//
// '_pdfioArrayDecrypt()' - Decrypt values in an array.
//
bool // O - `true` on success, `false` on error
_pdfioArrayDecrypt(pdfio_file_t *pdf, // I - PDF file
pdfio_obj_t *obj, // I - Object
pdfio_array_t *a, // I - Array
size_t depth) // I - Depth
{
size_t i; // Looping var
_pdfio_value_t *v; // Current value
for (i = a->num_values, v = a->values; i > 0; i --, v ++)
{
if (!_pdfioValueDecrypt(pdf, obj, v, depth))
return (false);
}
return (true);
}
//
// '_pdfioArrayDebug()' - Print the contents of an array.
//

24
pdfio-dict.c
View File

@ -158,6 +158,30 @@ pdfioDictCreate(pdfio_file_t *pdf) // I - PDF file
}
//
// '_pdfioDictDecrypt()' - Decrypt the values in a dictionary.
//
bool // O - `true` on success, `false` on error
_pdfioDictDecrypt(pdfio_file_t *pdf, // I - PDF file
pdfio_obj_t *obj, // I - Object
pdfio_dict_t *dict, // I - Dictionary
size_t depth) // I - Depth
{
size_t i; // Looping var
_pdfio_pair_t *pair; // Current pair
for (i = dict->num_pairs, pair = dict->pairs; i > 0; i --, pair ++)
{
if (strcmp(pair->key, "ID") && !_pdfioValueDecrypt(pdf, obj, &pair->value, depth + 1))
return (false);
}
return (true);
}
//
// '_pdfioDictDebug()' - Dump a dictionary to stderr.
//

7
pdfio-object.c
View File

@ -466,6 +466,13 @@ _pdfioObjLoad(pdfio_obj_t *obj) // I - Object
PDFIO_DEBUG("_pdfioObjLoad: stream_offset=%lu.\n", (unsigned long)obj->stream_offset);
}
// Decrypt as needed...
if (obj->pdf->encryption)
{
if (!_pdfioValueDecrypt(obj->pdf, obj, &obj->value, 0))
return (false);
}
PDFIO_DEBUG("_pdfioObjLoad: ");
PDFIO_DEBUG_VALUE(&obj->value);
PDFIO_DEBUG("\n");

3
pdfio-private.h
View File

@ -322,6 +322,7 @@ struct _pdfio_stream_s // Stream
// Functions...
//
extern bool _pdfioArrayDecrypt(pdfio_file_t *pdf, pdfio_obj_t *obj, pdfio_array_t *a, size_t depth) _PDFIO_INTERNAL;
extern void _pdfioArrayDebug(pdfio_array_t *a, FILE *fp) _PDFIO_INTERNAL;
extern void _pdfioArrayDelete(pdfio_array_t *a) _PDFIO_INTERNAL;
extern _pdfio_value_t *_pdfioArrayGetValue(pdfio_array_t *a, size_t n) _PDFIO_INTERNAL;
@ -346,6 +347,7 @@ extern void _pdfioCryptoSHA256Finish(_pdfio_sha256_t *ctx, uint8_t *Message_Dig
extern bool _pdfioCryptoUnlock(pdfio_file_t *pdf, pdfio_password_cb_t password_cb, void *password_data) _PDFIO_INTERNAL;
extern void _pdfioDictClear(pdfio_dict_t *dict, const char *key) _PDFIO_INTERNAL;
extern bool _pdfioDictDecrypt(pdfio_file_t *pdf, pdfio_obj_t *obj, pdfio_dict_t *dict, size_t depth) _PDFIO_INTERNAL;
extern void _pdfioDictDebug(pdfio_dict_t *dict, FILE *fp) _PDFIO_INTERNAL;
extern void _pdfioDictDelete(pdfio_dict_t *dict) _PDFIO_INTERNAL;
extern _pdfio_value_t *_pdfioDictGetValue(pdfio_dict_t *dict, const char *key) _PDFIO_INTERNAL;
@ -389,6 +391,7 @@ extern void _pdfioTokenPush(_pdfio_token_t *tb, const char *token) _PDFIO_INTER
extern bool _pdfioTokenRead(_pdfio_token_t *tb, char *buffer, size_t bufsize);
extern _pdfio_value_t *_pdfioValueCopy(pdfio_file_t *pdfdst, _pdfio_value_t *vdst, pdfio_file_t *pdfsrc, _pdfio_value_t *vsrc) _PDFIO_INTERNAL;
extern bool _pdfioValueDecrypt(pdfio_file_t *pdf, pdfio_obj_t *obj, _pdfio_value_t *v, size_t depth) _PDFIO_INTERNAL;
extern void _pdfioValueDebug(_pdfio_value_t *v, FILE *fp) _PDFIO_INTERNAL;
extern void _pdfioValueDelete(_pdfio_value_t *v) _PDFIO_INTERNAL;
extern _pdfio_value_t *_pdfioValueRead(pdfio_file_t *pdf, pdfio_obj_t *obj, _pdfio_token_t *ts, _pdfio_value_t *v, size_t depth) _PDFIO_INTERNAL;

271
pdfio-value.c
View File

@ -10,6 +10,13 @@
#include "pdfio-private.h"
//
// Local functions...
//
static time_t get_date_time(const char *s);
//
// '_pdfioValueCopy()' - Copy a value to a PDF file.
//
@ -105,6 +112,97 @@ _pdfioValueCopy(pdfio_file_t *pdfdst, // I - Destination PDF file
}
//
// '_pdfioValueDecrypt()' - Decrypt a value.
//
bool // O - `true` on success, `false` on error
_pdfioValueDecrypt(pdfio_file_t *pdf, // I - PDF file
pdfio_obj_t *obj, // I - Object
_pdfio_value_t *v, // I - Value
size_t depth)// I - Depth
{
_pdfio_crypto_ctx_t ctx; // Decryption context
_pdfio_crypto_cb_t cb; // Decryption callback
size_t ivlen; // Number of initialization vector bytes
uint8_t temp[32768]; // Temporary buffer for decryption
size_t templen; // Number of actual data bytes
time_t timeval; // Date/time value
if (depth > PDFIO_MAX_DEPTH)
{
_pdfioFileError(pdf, "Value too deep.");
return (false);
}
switch (v->type)
{
case PDFIO_VALTYPE_ARRAY :
return (_pdfioArrayDecrypt(pdf, obj, v->value.array, depth + 1));
break;
case PDFIO_VALTYPE_DICT :
return (_pdfioDictDecrypt(pdf, obj, v->value.dict, depth + 1));
break;
case PDFIO_VALTYPE_BINARY :
// Decrypt the binary string...
if (v->value.binary.datalen > (sizeof(temp) - 32))
{
_pdfioFileError(pdf, "Unable to read encrypted binary string - too long.");
return (false);
}
ivlen = v->value.binary.datalen;
if ((cb = _pdfioCryptoMakeReader(pdf, obj, &ctx, v->value.binary.data, &ivlen)) == NULL)
return (false);
templen = (cb)(&ctx, temp, v->value.binary.data + ivlen, v->value.binary.datalen - ivlen);
// Copy the decrypted string back to the value and adjust the length...
memcpy(v->value.binary.data, temp, templen);
if (pdf->encryption >= PDFIO_ENCRYPTION_AES_128)
v->value.binary.datalen = templen - temp[templen - 1];
else
v->value.binary.datalen = templen;
break;
case PDFIO_VALTYPE_STRING :
// Decrypt regular string...
templen = strlen(v->value.string);
if (templen > (sizeof(temp) - 33))
{
_pdfioFileError(pdf, "Unable to read encrypted string - too long.");
return (false);
}
ivlen = templen;
if ((cb = _pdfioCryptoMakeReader(pdf, obj, &ctx, (uint8_t *)v->value.string, &ivlen)) == NULL)
return (false);
templen = (cb)(&ctx, temp, (uint8_t *)v->value.string + ivlen, templen - ivlen);
temp[templen] = '\0';
if ((timeval = get_date_time((char *)temp)) != 0)
{
// Change the type to date...
v->type = PDFIO_VALTYPE_DATE;
v->value.date = timeval;
}
else
{
// Copy the decrypted string back to the value...
v->value.string = pdfioStringCreate(pdf, (char *)temp);
}
break;
}
return (true);
}
//
// '_pdfioValueDebug()' - Print the contents of a value.
//
@ -196,6 +294,7 @@ _pdfioValueRead(pdfio_file_t *pdf, // I - PDF file
size_t depth) // I - Depth of value
{
char token[32768]; // Token buffer
time_t timeval; // Date/time value
#ifdef DEBUG
static const char * const valtypes[] =
{
@ -245,73 +344,10 @@ _pdfioValueRead(pdfio_file_t *pdf, // I - PDF file
if ((v->value.dict = _pdfioDictRead(pdf, obj, tb, depth + 1)) == NULL)
return (NULL);
}
else if (!strncmp(token, "(D:", 3))
else if (!strncmp(token, "(D:", 3) && (timeval = get_date_time(token + 1)) != 0)
{
// Possible date value of the form:
//
// (D:YYYYMMDDhhmmssZ)
// (D:YYYYMMDDhhmmss+HH'mm)
// (D:YYYYMMDDhhmmss-HH'mm)
//
int i; // Looping var
struct tm dateval; // Date value
int offset; // Date offset
for (i = 3; i < 17; i ++)
{
if (!isdigit(token[i] & 255))
break;
}
if (i >= 17)
{
if (token[i] == 'Z')
{
i ++;
}
else if (token[i] == '-' || token[i] == '+')
{
if (isdigit(token[i + 1] & 255) && isdigit(token[i + 2] & 255) && token[i + 3] == '\'' && isdigit(token[i + 4] & 255) && isdigit(token[i + 5] & 255))
{
i += 6;
if (token[i] == '\'')
i ++;
}
}
}
if (token[i])
{
// Just a string...
v->type = PDFIO_VALTYPE_STRING;
v->value.string = pdfioStringCreate(pdf, token + 1);
}
else
{
// Date value...
memset(&dateval, 0, sizeof(dateval));
dateval.tm_year = (token[3] - '0') * 1000 + (token[4] - '0') * 100 + (token[5] - '0') * 10 + token[6] - '0' - 1900;
dateval.tm_mon = (token[7] - '0') * 10 + token[8] - '0' - 1;
dateval.tm_mday = (token[9] - '0') * 10 + token[10] - '0';
dateval.tm_hour = (token[11] - '0') * 10 + token[12] - '0';
dateval.tm_min = (token[13] - '0') * 10 + token[14] - '0';
dateval.tm_sec = (token[15] - '0') * 10 + token[16] - '0';
if (token[17] == 'Z')
{
offset = 0;
}
else
{
offset = (token[18] - '0') * 600 + (token[19] - '0') * 60 + (token[20] - '0') * 10 + token[21] - '0';
if (token[17] == '-')
offset = -offset;
}
v->type = PDFIO_VALTYPE_DATE;
v->value.date = mktime(&dateval) + offset;
}
v->type = PDFIO_VALTYPE_DATE;
v->value.date = timeval;
}
else if (token[0] == '(')
{
@ -363,36 +399,6 @@ _pdfioValueRead(pdfio_file_t *pdf, // I - PDF file
*dataptr++ = (unsigned char)d;
}
if (obj && pdf->encryption)
{
// Decrypt the string...
_pdfio_crypto_ctx_t ctx; // Decryption context
_pdfio_crypto_cb_t cb; // Decryption callback
size_t ivlen; // Number of initialization vector bytes
uint8_t temp[32768]; // Temporary buffer for decryption
size_t templen; // Number of actual data bytes
if (v->value.binary.datalen > (sizeof(temp) - 32))
{
_pdfioFileError(pdf, "Unable to read encrypted binary string - too long.");
return (false);
}
ivlen = v->value.binary.datalen;
if ((cb = _pdfioCryptoMakeReader(pdf, obj, &ctx, v->value.binary.data, &ivlen)) == NULL)
return (false);
templen = (cb)(&ctx, temp, v->value.binary.data + ivlen, v->value.binary.datalen - ivlen);
// Copy the decrypted string back to the value and adjust the length...
memcpy(v->value.binary.data, temp, templen);
if (pdf->encryption >= PDFIO_ENCRYPTION_AES_128)
v->value.binary.datalen = templen - temp[templen - 1];
else
v->value.binary.datalen = templen;
}
}
else if (strchr("0123456789-+.", token[0]) != NULL)
{
@ -728,3 +734,76 @@ _pdfioValueWrite(pdfio_file_t *pdf, // I - PDF file
return (false);
}
//
// 'get_date_time()' - Convert PDF date/time value to time_t.
//
static time_t // O - Time in seconds
get_date_time(const char *s) // I - PDF date/time value
{
int i; // Looping var
struct tm dateval; // Date value
int offset; // Date offset
// Possible date value of the form:
//
// (D:YYYYMMDDhhmmssZ)
// (D:YYYYMMDDhhmmss+HH'mm)
// (D:YYYYMMDDhhmmss-HH'mm)
//
for (i = 2; i < 16; i ++)
{
if (!isdigit(s[i] & 255) || !s[i])
break;
}
if (i >= 16)
{
if (s[i] == 'Z')
{
i ++;
}
else if (s[i] == '-' || s[i] == '+')
{
if (isdigit(s[i + 1] & 255) && isdigit(s[i + 2] & 255) && s[i + 3] == '\'' && isdigit(s[i + 4] & 255) && isdigit(s[i + 5] & 255))
{
i += 6;
if (s[i] == '\'')
i ++;
}
}
}
if (s[i])
{
// Just a string...
return (0);
}
// Date value...
memset(&dateval, 0, sizeof(dateval));
dateval.tm_year = (s[2] - '0') * 1000 + (s[3] - '0') * 100 + (s[4] - '0') * 10 + s[5] - '0' - 1900;
dateval.tm_mon = (s[6] - '0') * 10 + s[7] - '0' - 1;
dateval.tm_mday = (s[8] - '0') * 10 + s[9] - '0';
dateval.tm_hour = (s[10] - '0') * 10 + s[11] - '0';
dateval.tm_min = (s[12] - '0') * 10 + s[13] - '0';
dateval.tm_sec = (s[14] - '0') * 10 + s[15] - '0';
if (s[16] == 'Z')
{
offset = 0;
}
else
{
offset = (s[17] - '0') * 600 + (s[18] - '0') * 60 + (s[19] - '0') * 10 + s[20] - '0';
if (s[16] == '-')
offset = -offset;
}
return (mktime(&dateval) + offset);
}