Bug#500279: ftpd command line split
tags 500279 + patch security
clone 500279 -1
reassign -1 ftpd-ssl
thanks
Unfortunately this came in just as I was going on VAC.
Whoever fixes this in linux-ftpd please NMU linux-ftpd-ssl as well.
If nobody NMUs, I'll fix this in linux-ftpd-ssl after I get back from VAC.
The attached patch is a port of the openbsd fix to linux-ftpd-ssl,
but it also applies to the vanilla linux-ftpd (with offsets)
Please note I haven't had time to do more than test that the fix
compiles, so please test before uploading.
Ian
--
Ian Beckwith - ianb@erislabs.net - http://erislabs.net/ianb/
GPG fingerprint: AF6C C0F1 1E74 424B BCD5 4814 40EC C154 A8BA C1EA
diff --git a/ftpd/extern.h b/ftpd/extern.h
index fe819c2..0178b35 100644
--- a/ftpd/extern.h
+++ b/ftpd/extern.h
@@ -43,7 +43,7 @@ void dologout __P((int));
void fatal __P((const char *));
int ftpd_pclose __P((FILE *));
FILE *ftpd_popen __P((char *, const char *));
-char *ftpd_getline __P((char *, int, FILE *));
+int ftpd_getline __P((char *, int, FILE *));
void ftpdlogwtmp __P((const char *, const char *, const char *));
void lreply __P((int, const char *, ...));
void makedir __P((char *));
diff --git a/ftpd/ftpcmd.y b/ftpd/ftpcmd.y
index 1af612f..f833735 100644
--- a/ftpd/ftpcmd.y
+++ b/ftpd/ftpcmd.y
@@ -981,7 +981,7 @@ static struct tab *lookup(struct tab *p, char *cmd)
/*
* getline - a hacked up version of fgets to ignore TELNET escape codes.
*/
-char * ftpd_getline(char *s, int n, FILE *iop)
+int ftpd_getline(char *s, int n, FILE *iop)
{
int c;
register char *cs;
@@ -996,7 +996,7 @@ char * ftpd_getline(char *s, int n, FILE *iop)
if (debug)
syslog(LOG_FTP | LOG_DEBUG, "command: %s", s);
tmpline[0] = '\0';
- return(s);
+ return(0);
}
if (c == 0)
tmpline[0] = '\0';
@@ -1038,11 +1038,22 @@ char * ftpd_getline(char *s, int n, FILE *iop)
}
}
*cs++ = c;
- if (--n <= 0 || c == '\n')
+ if (--n <= 0) {
+ /*
+ * If command doesn't fit into buffer, discard the
+ * rest of the command and indicate truncation.
+ * This prevents the command to be split up into
+ * multiple commands.
+ */
+ while (c != '\n' && (c = GETC(iop)) != EOF)
+ ;
+ return (-2);
+ }
+ if (c == '\n')
break;
}
if (c == EOF && cs == s)
- return (NULL);
+ return (-1);
*cs++ = '\0';
if (debug) {
if (!guest && strncasecmp("pass ", s, 5) == 0) {
@@ -1062,7 +1073,7 @@ char * ftpd_getline(char *s, int n, FILE *iop)
syslog(LOG_FTP | LOG_DEBUG, "command: %.*s", len, s);
}
}
- return (s);
+ return (0);
}
void toolong(int signo)
@@ -1091,9 +1102,14 @@ static int yylex(void)
case CMD:
(void) signal(SIGALRM, toolong);
(void) alarm((unsigned) timeout);
- if (ftpd_getline(cbuf, sizeof(cbuf)-1, stdin)==NULL) {
- reply(221, "You could at least say goodbye.");
- dologout(0);
+ n=ftpd_getline(cbuf, sizeof(cbuf)-1, stdin)
+ if (n == -1) {
+ reply(221, "You could at least say goodbye.");
+ dologout(0);
+ } else if (n == -2) {
+ reply(500, "Command too long.");
+ alarm(0);
+ continue;
}
(void) alarm(0);
if ((cp = strchr(cbuf, '\r'))) {
diff --git a/ftpd/ftpd.c b/ftpd/ftpd.c
index 8d60811..eed3f50 100644
--- a/ftpd/ftpd.c
+++ b/ftpd/ftpd.c
@@ -2590,6 +2590,7 @@ void dologout(int status)
static void myoob(int signo)
{
char *cp;
+ int ret;
int save_errno = errno;
(void)signo;
@@ -2598,9 +2599,13 @@ static void myoob(int signo)
if (!transflag)
return;
cp = tmpline;
- if (ftpd_getline(cp, 7, stdin) == NULL) {
+ ret=ftpd_getline(cp, 7, stdin);
+ if (ret == -1) {
reply(221, "You could at least say goodbye.");
dologout(0);
+ } else if (ret == -2) {
+ /* Ignore truncated command */
+ return;
}
upper(cp);
if (strcmp(cp, "ABOR\r\n") == 0) {
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