Merge branch 'fix/sec-server' into fix/sec-integration

src/shared/config.c

@@ -613,19 +613,36 @@ int config_parse_transport_dest(Config* config) {
   int daemon_ret = config_parse_daemon_dest(config);
   if (daemon_ret != 0)
     return daemon_ret;
-  config_parse_ssh_dest(config);
-  return 0;
+  /* 0 for a local destination (nothing parsed) or a valid SSH destination;
+   * -1 (already logged) for an injection-shaped user@host. */
+  return config_parse_ssh_dest(config);
 }
 
-void config_parse_ssh_dest(Config* config) {
+int config_parse_ssh_dest(Config* config) {
+  if (!config || !config->receive_root_directory)
+    return 0;
   if (!config_is_remote_dest(config->receive_root_directory))
-    return;
+    return 0;
+  const char* dest = config->receive_root_directory;
+  const char* colon = strchr(dest, ':');
+  /* The user@host token is passed to ssh in option position, so a user or host
+   * beginning with '-' would be consumed by ssh as an option (argument
+   * injection: e.g. "-oProxyCommand=...").  An empty host is likewise not a
+   * valid destination.  Validate before any wire/argv construction. */
+  const char* at = memchr(dest, '@', (size_t)(colon - dest));
+  const char* host = at ? at + 1 : dest;
+  size_t host_len = (size_t)(colon - host);
+  size_t user_len = at ? (size_t)(at - dest) : 0;
+  if (host_len == 0 || host[0] == '-' || (user_len > 0 && dest[0] == '-'))
+    return daemon_dest_parse_error("invalid remote destination user@host (must not be empty or "
+                                   "start with '-')",
+                                   dest);
   config->transport = TRANSPORT_SSH;
-  config->ssh_destination = str_dup(config->receive_root_directory);
-  const char* colon = strchr(config->receive_root_directory, ':');
+  config->ssh_destination = str_dup(dest);
   char* path = str_dup(colon + 1);
   free(config->receive_root_directory);
   config->receive_root_directory = path;
+  return 0;
 }
 
 void config_burn_auth(Config* config) {

src/shared/config.h

@@ -851,7 +851,10 @@ bool config_send(int file_descriptor, const Config* config);
 bool config_send_wire_block(int file_descriptor, const Config* config);
 Config* config_receive(int file_descriptor);
 bool config_is_remote_dest(const char* s);
-void config_parse_ssh_dest(Config* config);
+/* Parse a single-colon host:path SSH destination (0 = not an SSH destination or
+ * parsed successfully, -1 = rejected, e.g. a user@host beginning with '-'; the
+ * reason is logged). */
+int config_parse_ssh_dest(Config* config);
 
 /* A ConfigValidateFunc may return this sentinel to tell
  * config_receive_with_validate that the callback ALREADY sent a terminal status

src/shared/credentials.c

@@ -158,13 +158,13 @@ static int hex_value(char c) {
  * digits.  Such a line is refused loudly (and never accepted) so an operator
  * cannot keep a replayable bearer digest in place after the protocol bump. */
 static bool secret_is_legacy_hex(const char* s) {
-  if (!s)
+  if (!s || strlen(s) != 64)
     return false;
   for (int i = 0; i < 64; i++) {
     if (hex_value(s[i]) < 0)
       return false;
   }
-  return s[64] == '\0';
+  return true;
 }
 
 bool credentials_b64_encode(const uint8_t* in, size_t n, char* out, size_t out_sz) {

src/shared/daemon_conf.c

@@ -133,6 +133,7 @@ static bool store_host_list(char*** list, int* count, const char* value, const c
     return false;
   }
   char* save = NULL;
+  int added = 0;
   for (char* token = strtok_r(copy, ", \t", &save); token; token = strtok_r(NULL, ", \t", &save)) {
     if (!host_pattern_valid(token)) {
       if (module_name)
@@ -163,8 +164,20 @@ static bool store_host_list(char*** list, int* count, const char* value, const c
       return false;
     }
     (*list)[(*count)++] = dup;
+    added++;
   }
   free(copy);
+  /* A present key with an empty (or separator-only) value would otherwise
+   * install a zero-length list, i.e. no ACL at all: a strict-parse config must
+   * never silently turn a restrictive directive into "allow everyone". */
+  if (added == 0) {
+    if (module_name)
+      set_error(err, err_size, "module '%s': '%s' must list at least one host pattern", module_name,
+                key);
+    else
+      set_error(err, err_size, "'%s' must list at least one host pattern", key);
+    return false;
+  }
   return true;
 }
 
@@ -403,6 +416,7 @@ static bool apply_module_key(DaemonModule* module, char* key, char* value, char*
       return false;
     }
     char* save = NULL;
+    int added = 0;
     for (char* token = strtok_r(list, ",", &save); token; token = strtok_r(NULL, ",", &save)) {
       const char* user = trim_ws(token);
       if (*user == '\0')
@@ -430,8 +444,16 @@ static bool apply_module_key(DaemonModule* module, char* key, char* value, char*
         return false;
       }
       module->auth_users[module->auth_user_count++] = dup;
+      added++;
     }
     free(list);
+    /* An empty/separator-only value must not silently disable authentication:
+     * the key's presence is an explicit request for an allow-list. */
+    if (added == 0) {
+      set_error(err, err_size, "module '%s': 'auth users' must list at least one user",
+                module->name);
+      return false;
+    }
     return true;
   }
   if (key_equals(key, "max connections"))
@@ -439,10 +461,10 @@ static bool apply_module_key(DaemonModule* module, char* key, char* value, char*
                               "max connections", module->name, err, err_size);
   if (key_equals(key, "hosts allow"))
     return store_host_list(&module->hosts_allow, &module->hosts_allow_count, value, "hosts allow",
-                           false, module->name, err, err_size);
+                           module->name, false, err, err_size);
   if (key_equals(key, "hosts deny"))
     return store_host_list(&module->hosts_deny, &module->hosts_deny_count, value, "hosts deny",
-                           false, module->name, err, err_size);
+                           module->name, false, err, err_size);
   set_error(err, err_size, "unknown key '%s' in module '%s'", key, module->name);
   return false;
 }

src/shared/transport_ssh.c

@@ -75,6 +75,15 @@ static int parse_remote_dest(const char* dest, RemoteDest* r) {
     memcpy(r->host, dest, host_len);
     r->host[host_len] = '\0';
   }
+  /* The user@host token is handed to ssh in option position.  Reject anything
+   * that ssh would consume as an option (a leading '-') or an empty host, so a
+   * crafted destination can never inject an ssh option such as
+   * -oProxyCommand=... .  This mirrors config_parse_ssh_dest's validation and
+   * is defense-in-depth for callers that bypass it. */
+  if (r->host[0] == '\0' || r->host[0] == '-' || (r->user[0] != '\0' && r->user[0] == '-')) {
+    remote_dest_destroy(r);
+    return -1;
+  }
   return 0;
 }
 
@@ -216,10 +225,10 @@ char** ssh_build_client_argv(const char* rsh_command, int port, const char* user
     nwords = 1;
   }
 
-  /* Fixed tail: three -o pairs (6) + optional -p/value (2) + user@host +
-   * remote command + terminating NULL. */
+  /* Fixed tail: three -o pairs (6) + optional -p/value (2) + the "--" end of
+   * options marker + user@host + remote command + terminating NULL. */
   int port_extra = (port > 0 && port != 22) ? 2 : 0;
-  size_t total = (size_t)nwords + 6 + (size_t)port_extra + 3;
+  size_t total = (size_t)nwords + 6 + (size_t)port_extra + 4;
   char** argv = calloc(total, sizeof(char*));
   if (!argv) {
     for (int i = 0; i < nwords; i++)
@@ -253,6 +262,13 @@ char** ssh_build_client_argv(const char* rsh_command, int port, const char* user
       goto fail_argv;
     ac++;
   }
+  /* End of options: guarantees the user@host token that follows is treated as
+   * the destination and never re-interpreted as an ssh option, even if every
+   * caller-side validation were bypassed. */
+  argv[ac] = str_dup("--");
+  if (!argv[ac])
+    goto fail_argv;
+  ac++;
   argv[ac] = str_dup(userhost);
   if (!argv[ac])
     goto fail_argv;

src/shared/transport_tls.c

@@ -4,7 +4,9 @@
 #include "transport_tcp.h"
 #include "utils.h"
 #include <arpa/inet.h>
+#include <fcntl.h>
 #include <openssl/err.h>
+#include <openssl/pem.h>
 #include <openssl/ssl.h>
 #include <signal.h>
 #include <stdio.h>
@@ -34,6 +36,59 @@ static void log_ssl_errors(void) {
   }
 }
 
+/* Load the TLS private key through an already-opened, no-follow descriptor so
+ * the owner/mode policy is checked on the SAME file object that is loaded: an
+ * attacker cannot swap the path between a stat() and a later open() (TOCTOU).
+ * The exact-owner / 0600 policy is preserved and group/other execute bits are
+ * rejected as well.  Ownership of the descriptor passes to the BIO and is
+ * released exactly once by BIO_free() (BIO_CLOSE). */
+static bool load_private_key_secure(SSL_CTX* ctx, const char* key) {
+  int fd = open(key, O_RDONLY | O_NOFOLLOW | O_CLOEXEC);
+  if (fd < 0) {
+    char* escaped = output_escape(key, false);
+    log_message(LOG_LEVEL_ERROR, "Failed to open private key: %s",
+                escaped ? escaped : "<allocation failed>");
+    free(escaped);
+    return false;
+  }
+  struct stat key_stat;
+  if (fstat(fd, &key_stat) != 0 || !S_ISREG(key_stat.st_mode) || key_stat.st_uid != geteuid() ||
+      (key_stat.st_mode & (S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH | S_IXGRP | S_IXOTH))) {
+    log_message(LOG_LEVEL_ERROR,
+                "TLS private key must be a regular file owned by the current user and private "
+                "(mode 0600)");
+    close(fd);
+    return false;
+  }
+  BIO* bio = BIO_new_fd(fd, BIO_CLOSE);
+  if (!bio) {
+    close(fd);
+    log_message(LOG_LEVEL_ERROR, "Failed to read private key");
+    return false;
+  }
+  EVP_PKEY* pkey = PEM_read_bio_PrivateKey(bio, NULL, NULL, NULL);
+  BIO_free(bio); /* releases fd via BIO_CLOSE */
+  if (!pkey) {
+    char* escaped = output_escape(key, false);
+    log_message(LOG_LEVEL_ERROR, "Failed to load private key: %s",
+                escaped ? escaped : "<allocation failed>");
+    free(escaped);
+    log_ssl_errors();
+    return false;
+  }
+  int use_ok = SSL_CTX_use_PrivateKey(ctx, pkey);
+  EVP_PKEY_free(pkey);
+  if (use_ok != 1) {
+    char* escaped = output_escape(key, false);
+    log_message(LOG_LEVEL_ERROR, "Failed to use private key: %s",
+                escaped ? escaped : "<allocation failed>");
+    free(escaped);
+    log_ssl_errors();
+    return false;
+  }
+  return true;
+}
+
 static SSL_CTX* create_ssl_ctx(bool is_server, const char* cert, const char* key,
                                const char* ca_path) {
   if (!is_server && !ca_path) {
@@ -56,12 +111,21 @@ static SSL_CTX* create_ssl_ctx(bool is_server, const char* cert, const char* key
 #ifdef SSL_OP_NO_RENEGOTIATION
   SSL_CTX_set_options(ctx, SSL_OP_NO_RENEGOTIATION);
 #endif
+  /* Let the server's own preference order decide the negotiated cipher rather
+   * than the client's, so a client cannot steer both peers into a weaker (but
+   * still offered) suite. */
+  SSL_CTX_set_options(ctx, SSL_OP_CIPHER_SERVER_PREFERENCE);
 
   if (SSL_CTX_set_min_proto_version(ctx, TLS1_2_VERSION) != 1) {
     SSL_CTX_free(ctx);
     return NULL;
   }
-  if (SSL_CTX_set_cipher_list(ctx, "HIGH:!aNULL:!eNULL:!MD5:!RC4:!3DES") != 1) {
+  /* TLS 1.2 and below: an AEAD-only suite list.  "HIGH" still includes CBC
+   * suites (Lucky13/POODLE-adjacent MAC-then-encrypt constructions), so restrict
+   * the list to ECDHE key agreement with an AEAD record cipher (AES-GCM or
+   * ChaCha20-Poly1305).  A NULL/weak/3DES cipher is never selectable. */
+  if (SSL_CTX_set_cipher_list(ctx, "ECDHE+AESGCM:ECDHE+CHACHA20:!aNULL:!eNULL:!MD5:!RC4:!3DES") !=
+      1) {
     SSL_CTX_free(ctx);
     return NULL;
   }
@@ -79,13 +143,6 @@ static SSL_CTX* create_ssl_ctx(bool is_server, const char* cert, const char* key
 #endif
 
   if (cert && key) {
-    struct stat key_stat;
-    if (stat(key, &key_stat) != 0 || !S_ISREG(key_stat.st_mode) || key_stat.st_uid != geteuid() ||
-        (key_stat.st_mode & (S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH))) {
-      log_message(LOG_LEVEL_ERROR, "TLS private key must be owned by the current user and private");
-      SSL_CTX_free(ctx);
-      return NULL;
-    }
     if (SSL_CTX_use_certificate_file(ctx, cert, SSL_FILETYPE_PEM) <= 0) {
       char* escaped = output_escape(cert, false);
       log_message(LOG_LEVEL_ERROR, "Failed to load certificate: %s",
@@ -95,12 +152,7 @@ static SSL_CTX* create_ssl_ctx(bool is_server, const char* cert, const char* key
       SSL_CTX_free(ctx);
       return NULL;
     }
-    if (SSL_CTX_use_PrivateKey_file(ctx, key, SSL_FILETYPE_PEM) <= 0) {
-      char* escaped = output_escape(key, false);
-      log_message(LOG_LEVEL_ERROR, "Failed to load private key: %s",
-                  escaped ? escaped : "<allocation failed>");
-      free(escaped);
-      log_ssl_errors();
+    if (!load_private_key_secure(ctx, key)) {
       SSL_CTX_free(ctx);
       return NULL;
     }
@@ -144,7 +196,16 @@ static SSL* wrap_fd_with_ssl(int fd, SSL_CTX* ctx, bool is_server, const char* h
   // Enable hostname verification for client connections when a hostname is provided.
   // Must be done before SSL_connect to take effect during the handshake.
   if (!is_server && hostname) {
-    if (SSL_set1_host(ssl, hostname) != 1) {
+    /* An IP-literal host must be verified against the certificate's IP SAN
+     * (X509_check_ip_asc), not as a DNS name: SSL_set1_host would look for a
+     * DNS SAN that a legitimate IP-SAN certificate never carries. */
+    struct in_addr ipv4;
+    struct in6_addr ipv6;
+    bool is_ip_literal =
+        inet_pton(AF_INET, hostname, &ipv4) == 1 || inet_pton(AF_INET6, hostname, &ipv6) == 1;
+    int set_ok = is_ip_literal ? X509_VERIFY_PARAM_set1_ip_asc(SSL_get0_param(ssl), hostname)
+                               : SSL_set1_host(ssl, hostname);
+    if (set_ok != 1) {
       SSL_free(ssl);
       return NULL;
     }