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fix possible timing attack along with a few typo #16

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fix possible timing attack along with a few typo #16

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ce4e98e
fix typos
LinRaymond2006 Aug 30, 2024
902f543
replace strcmp() with basic_password_match()
LinRaymond2006 Aug 30, 2024
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6 changes: 3 additions & 3 deletions ls.c
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Original file line number Diff line number Diff line change
Expand Up @@ -39,7 +39,7 @@ xgetpwuid(uid_t uid)
int i;

if (do_chroot)
return NULL; /* would'nt work anyway .. */
return NULL; /* wouldn't work anyway .. */

for (i = 0; i < used; i++) {
if (uids[i] == uid)
Expand Down Expand Up @@ -77,7 +77,7 @@ xgetgrgid(gid_t gid)
int i;

if (do_chroot)
return NULL; /* would'nt work anyway .. */
return NULL; /* wouldn't work anyway .. */

for (i = 0; i < used; i++) {
if (gids[i] == gid)
Expand Down Expand Up @@ -445,7 +445,7 @@ get_dir(struct REQUEST *req, char *filename)
/* reached cache size limit -> free last element */
#if 0
if (this->next != NULL) {
fprintf(stderr,"panic: this should'nt happen (%s:%d)\n",
fprintf(stderr,"panic: this shouldn't happen (%s:%d)\n",
__FILE__, __LINE__);
exit(1);
}
Expand Down
53 changes: 51 additions & 2 deletions request.c
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Original file line number Diff line number Diff line change
Expand Up @@ -347,6 +347,55 @@ static int sanity_checks(struct REQUEST *req)
return 0;
}

/* tested with:
printf("%d\n", basic_password_match("", ""));
printf("%d\n", basic_password_match("aaaa", ""));
printf("%d\n", basic_password_match("", "aaaa"));
printf("%d\n", basic_password_match("aaa", "aab"));
printf("%d\n", basic_password_match("aaa", "bbb"));
printf("%d\n", basic_password_match("aaaaaa", "aa"));
printf("%d\n", basic_password_match("aa", "aaaaaa"));
printf("%d\n", basic_password_match("a", "a"));
printf("%d\n", basic_password_match("aa", "aa"));
printf("%d\n", basic_password_match("aaa", "aaa"));
*/
int basic_password_match(const char *input, const char *password)
{
char unequal = 0;
unsigned int i = 0, j = 0;

/* special case: input or password is "" (null byte) */
if (!input[0] || !password[0]) return 0;

while (1) {

/* set the flag if any of the character mismatched */
unequal |= input[i] ^ password[j];

/* move on to next character */
i++;j++;

/* break if either input[] or password[] reaches 0x00 */
if (input[i] && password[j]) {
;
} else {
break;
}

}

/*
valid if: (input[i],password[j] is 0x00) and (all compared characters match)
(input[i] == 0x00) and (password[j] == 0x00) checks whether the length are equal
*/

if (!input[i] && !password[j] && !unequal) {
return 1;
} else {
return 0;
}
}

void
parse_request(struct REQUEST *req)
{
Expand Down Expand Up @@ -478,7 +527,7 @@ parse_request(struct REQUEST *req)
return;

/* check basic auth */
if (NULL != userpass && 0 != strcmp(userpass,req->auth)) {
if (NULL != userpass && !basic_password_match(userpass,req->auth)) {
mkerror(req,401,1);
return;
}
Expand Down Expand Up @@ -598,7 +647,7 @@ parse_request(struct REQUEST *req)
strcat(req->path,"/");
mkredirect(req);
} else {
/* anything else is'nt allowed here */
/* anything else isn't allowed here */
mkerror(req,403,1);
}
return;
Expand Down
2 changes: 1 addition & 1 deletion webfsd.c
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Original file line number Diff line number Diff line change
Expand Up @@ -294,7 +294,7 @@ access_log(struct REQUEST *req, time_t now)
/*
* loglevel usage
* ERR : fatal errors (which are followed by exit(1))
* WARNING: this should'nt happen error (oom, ...)
* WARNING: this shouldn't happen error (oom, ...)
* NOTICE : start/stop of the daemon
* INFO : "normal" errors (canceled downloads, timeouts,
* stuff what happens all the time)
Expand Down