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common: refactor vncauth.c #562

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common: refactor vncauth.c #562

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68 changes: 34 additions & 34 deletions src/common/vncauth.c
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Original file line number Diff line number Diff line change
Expand Up @@ -57,6 +57,25 @@
#include <sys/time.h>
#endif

/*
* make a string 8 Bytes long.
* If longer, shorten it.
* If shorter, zeropad it.
*/

static
void
zeroPadString(unsigned char *out, const char *in)
{
int inLen = strlen(in);
if(inLen > MAXPWLEN) {
inLen = MAXPWLEN;
}

memcpy(out, in, inLen);
memset(out+inLen, 0, MAXPWLEN-inLen);
}


/* libvncclient does not need this */
#ifndef rfbEncryptBytes
Expand All @@ -67,8 +86,7 @@
* as plaintext.
*/

static unsigned char fixedkey[8] = {23,82,107,6,35,78,88,7};

static unsigned char fixedkey[MAXPWLEN] = {23,82,107,6,35,78,88,7};

/*
* Encrypt a password and store it in a file. Returns 0 if successful,
Expand All @@ -91,22 +109,13 @@ rfbEncryptAndStorePasswd(char *passwd, char *fname)
#endif

/* pad password with nulls */

for (i = 0; i < 8; i++) {
if (i < strlen(passwd)) {
encryptedPasswd[i] = passwd[i];
} else {
encryptedPasswd[i] = 0;
}
}
zeroPadString(encryptedPasswd, passwd);

/* Do encryption in-place - this way we overwrite our copy of the plaintext
password */
encrypt_rfbdes(encryptedPasswd, &out_len, fixedkey, encryptedPasswd, sizeof(encryptedPasswd));

for (i = 0; i < 8; i++) {
putc(encryptedPasswd[i], fp);
}
fwrite(encryptedPasswd, 1, sizeof(encryptedPasswd), fp);

Check failure

Code scanning / CodeQL

Cleartext storage of sensitive information in file

This write into file 'fp' may contain unencrypted data from [this source.](1).
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I have not changed that. Its storing the same bytes in the file as before.
The Ci is not wrong, but i am not making it worse.


fclose(fp);
return 0;
Expand All @@ -124,28 +133,26 @@ rfbDecryptPasswdFromFile(char *fname)
{
FILE *fp;
int i, ch;
unsigned char *passwd = (unsigned char *)malloc(9);
unsigned char *passwd = (unsigned char *)malloc(MAXPWLEN+1);
int out_len;

if (!passwd || (fp = fopen(fname,"r")) == NULL) {
free(passwd);
return NULL;
}

for (i = 0; i < 8; i++) {
ch = getc(fp);
if (ch == EOF) {
fclose(fp);
free(passwd);
return NULL;
}
passwd[i] = ch;
}

size_t read = fread(passwd, 1, MAXPWLEN, fp);
fclose(fp);

if(!decrypt_rfbdes(passwd, &out_len, fixedkey, passwd, 8))
return NULL;
if (read < MAXPWLEN) {
free(passwd);
return NULL;
}

if(!decrypt_rfbdes(passwd, &out_len, fixedkey, passwd, MAXPWLEN)) {
free(passwd);
return NULL;
}

passwd[8] = 0;

Expand Down Expand Up @@ -188,14 +195,7 @@ rfbEncryptBytes(unsigned char *bytes, char *passwd)
int out_len;

/* key is simply password padded with nulls */

for (i = 0; i < 8; i++) {
if (i < strlen(passwd)) {
key[i] = passwd[i];
} else {
key[i] = 0;
}
}
zeroPadString(key, passwd);

encrypt_rfbdes(bytes, &out_len, key, bytes, CHALLENGESIZE);
}
Expand Down