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Diffstat (limited to 'usr.bin/ssh/sshconnect.c')
-rw-r--r--usr.bin/ssh/sshconnect.c217
1 files changed, 146 insertions, 71 deletions
diff --git a/usr.bin/ssh/sshconnect.c b/usr.bin/ssh/sshconnect.c
index 5159da41ced..fcb8dd15320 100644
--- a/usr.bin/ssh/sshconnect.c
+++ b/usr.bin/ssh/sshconnect.c
@@ -15,7 +15,7 @@ login (authentication) dialog.
*/
#include "includes.h"
-RCSID("$Id: sshconnect.c,v 1.11 1999/10/03 19:22:39 deraadt Exp $");
+RCSID("$Id: sshconnect.c,v 1.12 1999/10/03 21:50:04 provos Exp $");
#include <ssl/bn.h>
#include "xmalloc.h"
@@ -175,7 +175,8 @@ int ssh_create_socket(uid_t original_real_uid, int privileged)
and %p substituted for host and port, respectively) to use to contact
the daemon. */
-int ssh_connect(const char *host, int port, int connection_attempts,
+int ssh_connect(const char *host, struct sockaddr_in *hostaddr,
+ int port, int connection_attempts,
int anonymous, uid_t original_real_uid,
const char *proxy_command)
{
@@ -183,7 +184,6 @@ int ssh_connect(const char *host, int port, int connection_attempts,
int on = 1;
struct servent *sp;
struct hostent *hp;
- struct sockaddr_in hostaddr;
struct linger linger;
debug("ssh_connect: getuid %d geteuid %d anon %d",
@@ -217,15 +217,15 @@ int ssh_connect(const char *host, int port, int connection_attempts,
debug("Trying again...");
/* Try to parse the host name as a numeric inet address. */
- memset(&hostaddr, 0, sizeof(hostaddr));
- hostaddr.sin_family = AF_INET;
- hostaddr.sin_port = htons(port);
- hostaddr.sin_addr.s_addr = inet_addr(host);
- if ((hostaddr.sin_addr.s_addr & 0xffffffff) != 0xffffffff)
+ memset(hostaddr, 0, sizeof(hostaddr));
+ hostaddr->sin_family = AF_INET;
+ hostaddr->sin_port = htons(port);
+ hostaddr->sin_addr.s_addr = inet_addr(host);
+ if ((hostaddr->sin_addr.s_addr & 0xffffffff) != 0xffffffff)
{
/* Valid numeric IP address */
debug("Connecting to %.100s port %d.",
- inet_ntoa(hostaddr.sin_addr), port);
+ inet_ntoa(hostaddr->sin_addr), port);
/* Create a socket. */
sock = ssh_create_socket(original_real_uid,
@@ -236,7 +236,7 @@ int ssh_connect(const char *host, int port, int connection_attempts,
it will help with the problems of tcp_wrappers showing the
remote uid as root. */
temporarily_use_uid(original_real_uid);
- if (connect(sock, (struct sockaddr *)&hostaddr, sizeof(hostaddr))
+ if (connect(sock, (struct sockaddr *)hostaddr, sizeof(*hostaddr))
>= 0)
{
/* Successful connect. */
@@ -266,12 +266,12 @@ int ssh_connect(const char *host, int port, int connection_attempts,
for (i = 0; hp->h_addr_list[i]; i++)
{
/* Set the address to connect to. */
- hostaddr.sin_family = hp->h_addrtype;
- memcpy(&hostaddr.sin_addr, hp->h_addr_list[i],
- sizeof(hostaddr.sin_addr));
+ hostaddr->sin_family = hp->h_addrtype;
+ memcpy(&hostaddr->sin_addr, hp->h_addr_list[i],
+ sizeof(hostaddr->sin_addr));
debug("Connecting to %.200s [%.100s] port %d.",
- host, inet_ntoa(hostaddr.sin_addr), port);
+ host, inet_ntoa(hostaddr->sin_addr), port);
/* Create a socket for connecting. */
sock = ssh_create_socket(original_real_uid,
@@ -282,8 +282,8 @@ int ssh_connect(const char *host, int port, int connection_attempts,
it will help with tcp_wrappers showing the remote uid as
root. */
temporarily_use_uid(original_real_uid);
- if (connect(sock, (struct sockaddr *)&hostaddr,
- sizeof(hostaddr)) >= 0)
+ if (connect(sock, (struct sockaddr *)hostaddr,
+ sizeof(*hostaddr)) >= 0)
{
/* Successful connection. */
restore_uid();
@@ -990,13 +990,14 @@ int read_yes_or_no(const char *prompt, int defval)
void ssh_login(int host_key_valid,
RSA *own_host_key,
const char *orighost,
+ struct sockaddr_in *hostaddr,
Options *options, uid_t original_real_uid)
{
int i, type;
char *password;
struct passwd *pw;
BIGNUM *key;
- RSA *host_key;
+ RSA *host_key, *file_key;
RSA *public_key;
unsigned char session_key[SSH_SESSION_KEY_LENGTH];
const char *server_user, *local_user;
@@ -1004,6 +1005,7 @@ void ssh_login(int host_key_valid,
unsigned char check_bytes[8];
unsigned int supported_ciphers, supported_authentications, protocol_flags;
HostStatus host_status;
+ HostStatus ip_status;
int payload_len, clen, sum_len = 0;
u_int32_t rand = 0;
@@ -1056,6 +1058,15 @@ void ssh_login(int host_key_valid,
packet_get_bignum(host_key->n, &clen);
sum_len += clen;
+ if (options->check_host_ip && strcmp(host, inet_ntoa(hostaddr->sin_addr))) {
+ /* Store the host key from the known host file in here
+ * so that we can compare it with the key for the IP
+ * address. */
+ file_key = RSA_new();
+ file_key->n = BN_new();
+ file_key->e = BN_new();
+ }
+
/* Get protocol flags. */
protocol_flags = packet_get_int();
packet_set_protocol_flags(protocol_flags);
@@ -1082,12 +1093,13 @@ void ssh_login(int host_key_valid,
or in the systemwide list. */
host_status = check_host_in_hostfile(options->user_hostfile,
host, BN_num_bits(host_key->n),
- host_key->e, host_key->n);
+ host_key->e, host_key->n,
+ file_key->e, file_key->n);
if (host_status == HOST_NEW)
host_status = check_host_in_hostfile(options->system_hostfile, host,
BN_num_bits(host_key->n),
- host_key->e, host_key->n);
-
+ host_key->e, host_key->n,
+ file_key->e, file_key->n);
/* Force accepting of the host key for localhost and 127.0.0.1.
The problem is that if the home directory is NFS-mounted to multiple
machines, localhost will refer to a different machine in each of them,
@@ -1101,68 +1113,131 @@ void ssh_login(int host_key_valid,
host_status = HOST_OK;
}
- switch (host_status)
+ /* Also perform check for the ip address */
+ if (options->check_host_ip && strcmp(host, inet_ntoa(hostaddr->sin_addr))) {
+ RSA *ip_key = RSA_new();
+ ip_key->n = BN_new();
+ ip_key->e = BN_new();
+ ip_status = check_host_in_hostfile(options->user_hostfile,
+ inet_ntoa(hostaddr->sin_addr),
+ BN_num_bits(host_key->n),
+ host_key->e, host_key->n,
+ ip_key->e, ip_key->n);
+
+ if (ip_status == HOST_NEW)
+ ip_status = check_host_in_hostfile(options->system_hostfile,
+ inet_ntoa(hostaddr->sin_addr),
+ BN_num_bits(host_key->n),
+ host_key->e, host_key->n,
+ ip_key->e, ip_key->n);
+ if (ip_status == HOST_CHANGED && host_status == HOST_CHANGED &&
+ (BN_cmp(ip_key->e, file_key->e) || BN_cmp(ip_key->n, file_key->n)))
+ ip_status = HOST_DIFFER;
+
+ RSA_free(ip_key);
+ RSA_free(file_key);
+ } else
+ ip_status = host_status;
+
+ switch (host_status) {
+ case HOST_OK:
+ /* The host is known and the key matches. */
+ debug("Host '%.200s' is known and matches the host key.", host);
+ if (options->check_host_ip) {
+ if (ip_status == HOST_NEW) {
+ if (!add_host_to_hostfile(options->user_hostfile,
+ inet_ntoa(hostaddr->sin_addr),
+ BN_num_bits(host_key->n),
+ host_key->e, host_key->n))
+ log("Failed to add the host ip to the list of known hosts (%.30s).",
+ options->user_hostfile);
+ else
+ log("Warning: Permanently added host ip '%.30s' to the list of known hosts.", inet_ntoa(hostaddr->sin_addr));
+ } else if (ip_status != HOST_OK)
+ log("Warning: the host key differ from the key of the ip address '%.30s' differs", inet_ntoa(hostaddr->sin_addr));
+ }
+
+ break;
+ case HOST_NEW:
{
- case HOST_OK:
- /* The host is known and the key matches. */
- debug("Host '%.200s' is known and matches the host key.", host);
- break;
- case HOST_NEW:
+ char hostline[1000], *hostp = hostline;
/* The host is new. */
- if (options->strict_host_key_checking == 1)
- { /* User has requested strict host key checking. We will not
- add the host key automatically. The only alternative left
- is to abort. */
- fatal("No host key is known for %.200s and you have requested strict checking.", host);
- }
- else if (options->strict_host_key_checking == 2) /* The default */
- {
- char prompt[1024];
- sprintf(prompt,
- "The authenticity of host '%.200s' can't be established.\n"
- "Are you sure you want to continue connecting (yes/no)? ",
- host);
- if (!read_yes_or_no(prompt, -1))
- fatal("Aborted by user!\n");
- }
+ if (options->strict_host_key_checking == 1) {
+ /* User has requested strict host key checking. We will not
+ add the host key automatically. The only alternative left
+ is to abort. */
+ fatal("No host key is known for %.200s and you have requested strict checking.", host);
+ } else if (options->strict_host_key_checking == 2) { /* The default */
+ char prompt[1024];
+ snprintf(prompt, sizeof(prompt),
+ "The authenticity of host '%.200s' can't be established.\n"
+ "Are you sure you want to continue connecting (yes/no)? ",
+ host);
+ if (!read_yes_or_no(prompt, -1))
+ fatal("Aborted by user!\n");
+ }
+
+ if (options->check_host_ip && ip_status == HOST_NEW &&
+ strcmp(host, inet_ntoa(hostaddr->sin_addr)))
+ snprintf(hostline, sizeof(hostline), "%s,%s",
+ host, inet_ntoa(hostaddr->sin_addr));
+ else
+ hostp = host;
+
/* If not in strict mode, add the key automatically to the local
known_hosts file. */
- if (!add_host_to_hostfile(options->user_hostfile, host,
+ if (!add_host_to_hostfile(options->user_hostfile, hostp,
BN_num_bits(host_key->n),
host_key->e, host_key->n))
log("Failed to add the host to the list of known hosts (%.500s).",
options->user_hostfile);
else
- log("Warning: Permanently added host '%.200s' to the list of known hosts.", host);
- break;
- case HOST_CHANGED:
- /* The host key has changed. */
- error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
- error("@ WARNING: HOST IDENTIFICATION HAS CHANGED! @");
- error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
- error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
- error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
- error("It is also possible that the host key has just been changed.");
- error("Please contact your system administrator.");
- error("Add correct host key in %.100s to get rid of this message.",
- options->user_hostfile);
-
- /* If strict host key checking is in use, the user will have to edit
- the key manually and we can only abort. */
- if (options->strict_host_key_checking)
- fatal("Host key for %.200s has changed and you have requested strict checking.", host);
-
- /* If strict host key checking has not been requested, allow the
- connection but without password authentication. */
- error("Password authentication is disabled to avoid trojan horses.");
- options->password_authentication = 0;
- /* XXX Should permit the user to change to use the new id. This could
- be done by converting the host key to an identifying sentence, tell
- that the host identifies itself by that sentence, and ask the user
- if he/she whishes to accept the authentication. */
+ log("Warning: Permanently added '%.200s' to the list of known hosts.",
+ hostp);
break;
}
-
+ case HOST_CHANGED:
+ if (options->check_host_ip) {
+ if (ip_status != HOST_CHANGED) {
+ error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
+ error("@ WARNING: POSSIBLE DNS SPOOFNG DETECTED! @");
+ error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
+ error("The host key for %s has changed,", host);
+ error("but the key for the according IP address %s has",
+ inet_ntoa(hostaddr->sin_addr));
+ error("a different status. This could either mean that DNS");
+ error("SPOOFING is happening or the IP address for the host");
+ error("and its host key have changed at the same time");
+ }
+ }
+
+ /* The host key has changed. */
+ error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
+ error("@ WARNING: HOST IDENTIFICATION HAS CHANGED! @");
+ error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
+ error("IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!");
+ error("Someone could be eavesdropping on you right now (man-in-the-middle attack)!");
+ error("It is also possible that the host key has just been changed.");
+ error("Please contact your system administrator.");
+ error("Add correct host key in %.100s to get rid of this message.",
+ options->user_hostfile);
+
+ /* If strict host key checking is in use, the user will have to edit
+ the key manually and we can only abort. */
+ if (options->strict_host_key_checking)
+ fatal("Host key for %.200s has changed and you have requested strict checking.", host);
+
+ /* If strict host key checking has not been requested, allow the
+ connection but without password authentication. */
+ error("Password authentication is disabled to avoid trojan horses.");
+ options->password_authentication = 0;
+ /* XXX Should permit the user to change to use the new id. This could
+ be done by converting the host key to an identifying sentence, tell
+ that the host identifies itself by that sentence, and ask the user
+ if he/she whishes to accept the authentication. */
+ break;
+ }
+
/* Generate a session key. */
arc4random_stir();
generated by cgit v1.2.3 (git 2.25.1) at 2025-01-16 00:45:25 +0000