Bug#684554: unblock: rssh/2.3.3-5
Package: release.debian.org
Severity: normal
User: release.debian.org@packages.debian.org
Usertags: unblock
Please unblock package rssh. This fixes a security vulnerability in
the command-line parsing by applying upstream's patch and then
adjusting the Debian patches accordingly.
unblock rssh/2.3.3-5
Because the package uses TopGit (I intend to switch to git-dpm) and
generates a quilt series, the straight debdiff is not particularly
useful since it's a diff between various patches. Instead, attached
is the diff between the unpacked source for 2.3.3-4 and 2.3.3-5 with
all patches already applied, excluding the debian/patches directory
from the diff. This seems like a better diff to review. Let me know
if you want a diff in another format, however.
There are a few unfortunate whitespace-only hunks here that are due to
applying the upstream patch verbatim. I considered removing them, but
decided that keeping the official upstream patch applied verbatim was
a better idea since it made for easier comparisons.
There is a stable security upload pending. I've already contacted the
security team about that.
-- System Information:
Debian Release: wheezy/sid
APT prefers testing
APT policy: (990, 'testing'), (500, 'unstable'), (1, 'experimental')
Architecture: i386 (i686)
Kernel: Linux 3.2.0-2-686-pae (SMP w/4 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
diff -ru --exclude .pc --exclude patches rssh-2.3.3-4/debian/changelog rssh-2.3.3-5/debian/changelog
--- rssh-2.3.3-4/debian/changelog 2012-03-07 16:08:52.000000000 -0800
+++ rssh-2.3.3-5/debian/changelog 2012-08-10 22:14:54.000000000 -0700
@@ -1,3 +1,11 @@
+rssh (2.3.3-5) unstable; urgency=medium
+
+ * Apply upstream patch to close security vulnerability that permitted
+ clever manipulation of environment variables on the ssh command line
+ to bypass rssh checking. (CVE-2012-3478)
+
+ -- Russ Allbery <rra@debian.org> Fri, 10 Aug 2012 22:14:34 -0700
+
rssh (2.3.3-4) unstable; urgency=low
* Force libexecdir to /usr/lib/rssh. This is not a library package and
diff -ru --exclude .pc --exclude patches rssh-2.3.3-4/main.c.in rssh-2.3.3-5/main.c.in
--- rssh-2.3.3-4/main.c.in 2012-08-09 18:21:02.000000000 -0700
+++ rssh-2.3.3-5/main.c.in 2012-08-10 22:46:01.000000000 -0700
@@ -184,7 +184,7 @@
* determine if the command in cmdline is acceptable to run, and store
* name of program to exec in cmd
*/
- if ( !(*cmd = check_command_line(cmdline, opts)) ) return NULL;
+ if ( !(*cmd = get_command(cmdline, opts)) ) return NULL;
/* if we need to do chroot processing, do it */
if ( opts->shell_flags & RSSH_USE_CHROOT ){
@@ -254,7 +254,9 @@
}
/* return vector of pointers to command line arguments */
- return build_arg_vector(cmdline, 0);
+ argvec = build_arg_vector(cmdline, 0);
+ if (check_command_line(argvec, opts)) return argvec;
+ else return NULL;
}
void vers_info( void )
diff -ru --exclude .pc --exclude patches rssh-2.3.3-4/util.c rssh-2.3.3-5/util.c
--- rssh-2.3.3-4/util.c 2012-08-09 18:21:02.000000000 -0700
+++ rssh-2.3.3-5/util.c 2012-08-10 22:46:01.000000000 -0700
@@ -110,7 +110,7 @@
/* print error message to user and log attempt */
fprintf(stderr, "\nThis account is restricted by rssh.\n"
"%s\n\nIf you believe this is in error, please contact "
- "your system administrator.\n\n", cmd);
+ "your system administrator.\n\n", cmd);
if ( argc < 3 )
log_msg("user %s attempted to log in with a shell",
username);
@@ -136,31 +136,35 @@
*/
bool opt_exist(char *cl, char opt)
{
- int i = 0;
+ int i = 1;
int len;
- char *token;
- bool optstring = FALSE;
-
len = strlen(cl);
/* process command line character by character */
- while ( i < (len - 2) ){
- if ( cl[i] == ' ' || cl[i] == '\t' ){
- if ( cl[i+1] == '-' ){
- optstring = TRUE;
- i+=2;
- }
- }
- if ( cl[i] == opt && optstring ) return TRUE;
- if ( cl[i] == ' ' || cl[i] == '\t' || cl[i] == '-' )
- optstring = FALSE;
+ if (!(cl[0] == '-')) return FALSE;
+ while ( i < (len) ){
+ if ( cl[i] == opt ) return TRUE;
i++;
}
return FALSE;
}
+bool opt_filter(char **vec, const char opt)
+{
+ while (vec && *vec){
+ if (opt_exist(*vec, opt)){
+ fprintf(stderr, "\nillegal insecure %c option", opt);
+ log_msg("insecure %c option in command line!", opt);
+ return TRUE;
+ }
+ vec++;
+ }
+ return FALSE;
+}
+
+
bool check_command( char *cl, ShellOptions_t *opts, char *cmd, int cmdflag )
{
int cl_len; /* length of command line */
@@ -190,95 +194,98 @@
return FALSE;
}
+
/*
* check_rsync_e() - take the command line passed to rssh and look for a -e
- * option. If one is found, make sure --server is provided
- * and the option contains only the protocol information.
- * Returns 1 if the command line is safe; 0 otherwise.
+ * option. If one is found, make sure --server is provided
+ * and the option contains only the protocol information.
+ * Returns FALSE if the command line should not be allowed,
+ * TRUE if it is okay.
*/
-static int check_rsync_e( char *cl )
+static int rsync_e_okay( char **vec )
{
int status;
regex_t re;
+ int server = FALSE;
+ int e_found = FALSE;
+
+ static const char pattern[] = "^-([^-][^ ]*)?e[^.0-9]";
/*
* This is more complicated than it looks because we don't want to
- * trigger on the e in --server, but we do want to catch the common
+ * trigger on the e in --server, but we do want to allow the common
* case of -ltpre.iL (which contains -e.).
*/
- static const char pattern[] = "[ \t\v\f]-([^-][^ ]*)?e[^.0-9]";
-
- if ( strstr(cl, "--server") == NULL ) return 0;
if ( regcomp(&re, pattern, REG_EXTENDED | REG_NOSUB) != 0 ){
- return 0;
+ return FALSE;
+ }
+ while (vec && *vec){
+ if ( strcmp(*vec, "--server") == 0 ) server = TRUE;
+ if ( strncmp(*vec, "--", 2) != 0 && opt_exist(*vec, 'e') ){
+ e_found = TRUE;
+ if ( regexec(&re, *vec, 0, NULL, 0) == 0 ){
+ regfree(&re);
+ return FALSE;
+ }
+ }
+ vec++;
}
- status = regexec(&re, cl, 0, NULL, 0);
regfree(&re);
- return (status == 0) ? 0 : 1;
+ if ( e_found && !server ) return FALSE;
+ return TRUE;
}
+
/*
* check_command_line() - take the command line passed to rssh, and verify
- * that the specified command is one the user is
- * allowed to run. Return the path of the command
- * which will be run if it is ok, or return NULL if it
- * is not.
+ * that the specified command is one the user is
+ * allowed to run and validate the arguments. Return the
+ * path of the command which will be run if it is ok, or
+ * return NULL if it is not.
*/
-char *check_command_line( char *cl, ShellOptions_t *opts )
+char *check_command_line( char **cl, ShellOptions_t *opts )
{
- if ( check_command(cl, opts, PATH_SFTP_SERVER, RSSH_ALLOW_SFTP) )
+ if ( check_command(*cl, opts, PATH_SFTP_SERVER, RSSH_ALLOW_SFTP) )
return PATH_SFTP_SERVER;
- if ( check_command(cl, opts, PATH_SCP, RSSH_ALLOW_SCP) ){
+ if ( check_command(*cl, opts, PATH_SCP, RSSH_ALLOW_SCP) ){
/* filter -S option */
- if ( opt_exist(cl, 'S') ){
- fprintf(stderr, "\ninsecure -S option not allowed.");
- log_msg("insecure -S option in scp command line!");
- return NULL;
- }
+ if ( opt_filter(cl, 'S') ) return NULL;
return PATH_SCP;
}
- if ( check_command(cl, opts, PATH_CVS, RSSH_ALLOW_CVS) ){
- if ( opt_exist(cl, 'e') ){
- fprintf(stderr, "\ninsecure -e option not allowed.");
- log_msg("insecure -e option in cvs command line!");
- return NULL;
- }
+ if ( check_command(*cl, opts, PATH_CVS, RSSH_ALLOW_CVS) ){
+ if ( opt_filter(cl, 'e') ) return NULL;
return PATH_CVS;
}
- if ( check_command(cl, opts, PATH_RDIST, RSSH_ALLOW_RDIST) ){
+ if ( check_command(*cl, opts, PATH_RDIST, RSSH_ALLOW_RDIST) ){
/* filter -P option */
- if ( opt_exist(cl, 'P') ){
- fprintf(stderr, "\ninsecure -P option not allowed.");
- log_msg("insecure -P option in rdist command line!");
- return NULL;
- }
+ if ( opt_filter(cl, 'P') ) return NULL;
return PATH_RDIST;
}
- if ( check_command(cl, opts, PATH_RSYNC, RSSH_ALLOW_RSYNC) ){
+ if ( check_command(*cl, opts, PATH_RSYNC, RSSH_ALLOW_RSYNC) ){
/* filter -e option */
- if ( opt_exist(cl, 'e') && !check_rsync_e(cl) ){
- fprintf(stderr, "\ninsecure -e option not allowed.");
- log_msg("insecure -e option in rsync command line!");
+ if ( !rsync_e_okay(cl) ){
+ fprintf(stderr, "\nillegal insecure e option");
+ log_msg("insecure e option in rsync command line!");
return NULL;
}
-
- if ( strstr(cl, "--rsh=" ) ){
- fprintf(stderr, "\ninsecure --rsh= not allowed.");
- log_msg("insecure --rsh option in rsync command line!");
- return NULL;
+ while (cl && *cl){
+ if ( strstr(*cl, "--rsh=" ) ){
+ fprintf(stderr, "\ninsecure --rsh= not allowed.");
+ log_msg("insecure --rsh option in rsync command line!");
+ return NULL;
+ }
+ cl++;
}
-
return PATH_RSYNC;
}
-
- if ( check_command(cl, opts, PATH_SVNSERVE, RSSH_ALLOW_SVNSERVE) ){
+ if ( check_command(*cl, opts, PATH_SVNSERVE, RSSH_ALLOW_SVNSERVE) ){
/* check command line */
- if( strlen(cl) != 11 || strcmp(cl, "svnserve -t") ) {
+ if( cl[1] == NULL || strcmp(cl[1], "-t") != 0 || cl[2] != NULL){
fprintf(stderr, "\nextra svnserver parameter(s) not allowed.");
log_msg("unallowed option(s) in svnserver command line!");
return NULL;
@@ -286,11 +293,37 @@
return PATH_SVNSERVE;
}
+ /* No match, return NULL */
+ return NULL;
+}
+
+
+/*
+ * get_command() - take the command line passed to rssh, and verify
+ * that the specified command is one the user is allowed to run.
+ * Return the path of the command which will be run if it is ok,
+ * or return NULL if it is not.
+ */
+char *get_command( char *cl, ShellOptions_t *opts )
+{
+ if ( check_command(cl, opts, PATH_SFTP_SERVER, RSSH_ALLOW_SFTP) )
+ return PATH_SFTP_SERVER;
+ if ( check_command(cl, opts, PATH_SCP, RSSH_ALLOW_SCP) )
+ return PATH_SCP;
+ if ( check_command(cl, opts, PATH_CVS, RSSH_ALLOW_CVS) )
+ return PATH_CVS;
+ if ( check_command(cl, opts, PATH_RDIST, RSSH_ALLOW_RDIST) )
+ return PATH_RDIST;
+ if ( check_command(cl, opts, PATH_RSYNC, RSSH_ALLOW_RSYNC) )
+ return PATH_RSYNC;
+ if ( check_command(cl, opts, PATH_SVNSERVE, RSSH_ALLOW_SVNSERVE) )
+ return PATH_SVNSERVE;
return NULL;
}
+
/*
* extract_root() - takes a root directory and the full path to some other
* directory, and returns a pointer to a string which
@@ -306,7 +339,7 @@
len = strlen(root);
/* get rid of a trailing / from the root path */
if ( root[len - 1] == '/' ){
- root[len - 1] = '\0';
+ root[len - 1] = '\0';
len--;
}
if ( (strncmp(root, path, len)) ) return NULL;
diff -ru --exclude .pc --exclude patches rssh-2.3.3-4/util.h rssh-2.3.3-5/util.h
--- rssh-2.3.3-4/util.h 2012-08-09 18:21:02.000000000 -0700
+++ rssh-2.3.3-5/util.h 2012-08-10 22:46:01.000000000 -0700
@@ -33,7 +33,8 @@
#include "rsshconf.h"
void fail( int flags, int argc, char **argv );
-char *check_command_line( char *cl, ShellOptions_t *opts );
+char *check_command_line( char **cl, ShellOptions_t *opts );
+char *get_command( char *cl, ShellOptions_t *opts);
char *extract_root( char *root, char *path );
int validate_umask( const char *temp, int *mask );
int validate_access( const char *temp, bool *allow_sftp, bool *allow_scp,
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