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The FTP daemon was vulnerable to a DoS where an attacker could bind()

Browse Source 
up port 20 for an extended period of time and thus lock out all other
users from establishing PORT data connections. Don't hold on to the
bind() while we loop around waiting to see if we can make our
connection.

Being a DoS, it has security implications, giving it a short MFC
time.

MFC after:	1 day
This commit is contained in:
Crist J. Clark 2003-01-21 05:13:02 +00:00
parent dd3d8e7184
commit e509445689
1 changed files with 27 additions and 20 deletions
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47
libexec/ftpd/ftpd.c
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@ -1772,7 +1772,7 @@ dataconn(char *name, off_t size, char *mode)
{
char sizebuf[32];
FILE *file;
int retry = 0, tos;
int retry = 0, tos, conerrno;
file_size = size;
byte_count = 0;
@ -1840,28 +1840,35 @@ dataconn(char *name, off_t size, char *mode)
if (usedefault)
data_dest = his_addr;
usedefault = 1;
file = getdatasock(mode);
if (file == NULL) {
char hostbuf[BUFSIZ], portbuf[BUFSIZ];
getnameinfo((struct sockaddr *)&data_source,
data_source.su_len, hostbuf, sizeof(hostbuf) - 1,
portbuf, sizeof(portbuf),
NI_NUMERICHOST|NI_NUMERICSERV);
reply(425, "Can't create data socket (%s,%s): %s.",
hostbuf, portbuf, strerror(errno));
return (NULL);
}
data = fileno(file);
while (connect(data, (struct sockaddr *)&data_dest,
data_dest.su_len) < 0) {
if (errno == EADDRINUSE && retry < swaitmax) {
sleep((unsigned) swaitint);
retry += swaitint;
continue;
do {
file = getdatasock(mode);
if (file == NULL) {
char hostbuf[BUFSIZ], portbuf[BUFSIZ];
getnameinfo((struct sockaddr *)&data_source,
data_source.su_len, hostbuf, sizeof(hostbuf) - 1,
portbuf, sizeof(portbuf),
NI_NUMERICHOST|NI_NUMERICSERV);
reply(425, "Can't create data socket (%s,%s): %s.",
hostbuf, portbuf, strerror(errno));
return (NULL);
}
perror_reply(425, "Can't build data connection");
data = fileno(file);
conerrno = 0;
if (connect(data, (struct sockaddr *)&data_dest,
data_dest.su_len) == 0)
break;
conerrno = errno;
(void) fclose(file);
data = -1;
if (conerrno == EADDRINUSE) {
sleep((unsigned) swaitint);
retry += swaitint;
} else {
break;
}
} while (retry <= swaitmax);
if (conerrno != 0) {
perror_reply(425, "Can't build data connection");
return (NULL);
}
reply(150, "Opening %s mode data connection for '%s'%s.",