9 files changed, 247 insertions, 94 deletions

diff --git a/ChangeLog b/ChangeLog
index 7894490a3..4b1aa113b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -42,6 +42,11 @@
    - stevesk@cvs.openbsd.org 2001/05/19 19:57:09
      [channels.c]                               
      typo in error message                      
+   - markus@cvs.openbsd.org 2001/05/20 17:20:36                                 
+     [auth-rsa.c auth.c auth.h auth2.c servconf.c servconf.h sshd.8
+      sshd_config]
+     configurable authorized_keys{,2} location; originally from peter@; 
+     ok djm@ 
 
 20010528
  - (tim) [conifgure.in] add setvbuf test needed for sftp-int.c
@@ -5472,4 +5477,4 @@
  - Wrote replacements for strlcpy and mkdtemp
  - Released 1.0pre1
 
-$Id: ChangeLog,v 1.1235 2001/06/05 20:01:39 mouring Exp $
+$Id: ChangeLog,v 1.1236 2001/06/05 20:25:05 mouring Exp $
diff --git a/auth-rsa.c b/auth-rsa.c
index 59bee18bd..491ed81d6 100644
--- a/auth-rsa.c
+++ b/auth-rsa.c
@@ -14,7 +14,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: auth-rsa.c,v 1.40 2001/04/06 21:00:07 markus Exp $");
+RCSID("$OpenBSD: auth-rsa.c,v 1.41 2001/05/20 17:20:35 markus Exp $");
 
 #include <openssl/rsa.h>
 #include <openssl/md5.h>
@@ -122,7 +122,7 @@ auth_rsa_challenge_dialog(RSA *pk)
 int
 auth_rsa(struct passwd *pw, BIGNUM *client_n)
 {
-        char line[8192], file[MAXPATHLEN];
+        char line[8192], *file;
         int authenticated;
         u_int bits;
         FILE *f;
@@ -138,13 +138,14 @@ auth_rsa(struct passwd *pw, BIGNUM *client_n)
         temporarily_use_uid(pw);
 
         /* The authorized keys. */
-        snprintf(file, sizeof file, "%.500s/%.100s", pw->pw_dir,
-                 _PATH_SSH_USER_PERMITTED_KEYS);
+        file = authorized_keys_file(pw);
+        debug("trying public RSA key file %s", file);
 
         /* Fail quietly if file does not exist */
         if (stat(file, &st) < 0) {
                 /* Restore the privileged uid. */
                 restore_uid();
+                xfree(file);
                 return 0;
         }
         /* Open the file containing the authorized keys. */
@@ -154,43 +155,17 @@ auth_rsa(struct passwd *pw, BIGNUM *client_n)
                 restore_uid();
                 packet_send_debug("Could not open %.900s for reading.", file);
                 packet_send_debug("If your home is on an NFS volume, it may need to be world-readable.");
+                xfree(file);
                 return 0;
         }
-        if (options.strict_modes) {
-                int fail = 0;
-                char buf[1024];
-                /* Check open file in order to avoid open/stat races */
-                if (fstat(fileno(f), &st) < 0 ||
-                    (st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
-                    (st.st_mode & 022) != 0) {
-                        snprintf(buf, sizeof buf, "RSA authentication refused for %.100s: "
-                                 "bad ownership or modes for '%s'.", pw->pw_name, file);
-                        fail = 1;
-                } else {
-                        /* Check path to _PATH_SSH_USER_PERMITTED_KEYS */
-                        int i;
-                        static const char *check[] = {
-                                "", _PATH_SSH_USER_DIR, NULL
-                        };
-                        for (i = 0; check[i]; i++) {
-                                snprintf(line, sizeof line, "%.500s/%.100s", pw->pw_dir, check[i]);
-                                if (stat(line, &st) < 0 ||
-                                    (st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
-                                    (st.st_mode & 022) != 0) {
-                                        snprintf(buf, sizeof buf, "RSA authentication refused for %.100s: "
-                                                 "bad ownership or modes for '%s'.", pw->pw_name, line);
-                                        fail = 1;
-                                        break;
-                                }
-                        }
-                }
-                if (fail) {
-                        fclose(f);
-                        log("%s", buf);
-                        packet_send_debug("%s", buf);
-                        restore_uid();
-                        return 0;
-                }
+        if (options.strict_modes &&
+            secure_filename(f, file, pw->pw_uid, line, sizeof(line)) != 0) {
+                xfree(file);
+                fclose(f);
+                log("Authentication refused: %s", line);
+                packet_send_debug("Authentication refused: %s", line);
+                restore_uid();
+                return 0;
         }
         /* Flag indicating whether authentication has succeeded. */
         authenticated = 0;
@@ -285,6 +260,7 @@ auth_rsa(struct passwd *pw, BIGNUM *client_n)
         restore_uid();
 
         /* Close the file. */
+        xfree(file);
         fclose(f);
 
         RSA_free(pk);
diff --git a/auth.c b/auth.c
index 1f976eee2..07e5b8f05 100644
--- a/auth.c
+++ b/auth.c
@@ -23,7 +23,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: auth.c,v 1.21 2001/03/19 17:07:23 markus Exp $");
+RCSID("$OpenBSD: auth.c,v 1.22 2001/05/20 17:20:35 markus Exp $");
 
 #ifdef HAVE_LOGIN_H
 #include <login.h>
@@ -32,6 +32,8 @@ RCSID("$OpenBSD: auth.c,v 1.21 2001/03/19 17:07:23 markus Exp $");
 #include <shadow.h>
 #endif /* defined(HAVE_SHADOW_H) && !defined(DISABLE_SHADOW) */
 
+#include <libgen.h>
+
 #include "xmalloc.h"
 #include "match.h"
 #include "groupaccess.h"
@@ -40,6 +42,8 @@ RCSID("$OpenBSD: auth.c,v 1.21 2001/03/19 17:07:23 markus Exp $");
 #include "auth.h"
 #include "auth-options.h"
 #include "canohost.h"
+#include "buffer.h"
+#include "bufaux.h"
 
 /* import */
 extern ServerOptions options;
@@ -222,3 +226,132 @@ auth_root_allowed(char *method)
         log("ROOT LOGIN REFUSED FROM %.200s", get_remote_ipaddr());
         return 0;
 }
+
+
+/*
+ * Given a template and a passwd structure, build a filename
+ * by substituting % tokenised options. Currently, %% becomes '%',
+ * %h becomes the home directory and %u the username.
+ *
+ * This returns a buffer allocated by xmalloc.
+ */
+char *
+expand_filename(const char *filename, struct passwd *pw)
+{
+        Buffer buffer;
+        char *file;
+        const char *cp;
+
+        /*
+         * Build the filename string in the buffer by making the appropriate
+         * substitutions to the given file name.
+         */
+        buffer_init(&buffer);
+        for (cp = filename; *cp; cp++) {
+                if (cp[0] == '%' && cp[1] == '%') {
+                        buffer_append(&buffer, "%", 1);
+                        cp++;
+                        continue;
+                }
+                if (cp[0] == '%' && cp[1] == 'h') {
+                        buffer_append(&buffer, pw->pw_dir, strlen(pw->pw_dir));
+                        cp++;
+                        continue;
+                }
+                if (cp[0] == '%' && cp[1] == 'u') {
+                        buffer_append(&buffer, pw->pw_name,
+                             strlen(pw->pw_name));
+                        cp++;
+                        continue;
+                }
+                buffer_append(&buffer, cp, 1);
+        }
+        buffer_append(&buffer, "\0", 1);
+
+        /*
+         * Ensure that filename starts anchored. If not, be backward
+         * compatible and prepend the '%h/'
+         */
+        file = xmalloc(MAXPATHLEN);
+        cp = buffer_ptr(&buffer);
+        if (*cp != '/')
+                snprintf(file, MAXPATHLEN, "%s/%s", pw->pw_dir, cp);
+        else
+                strlcpy(file, cp, MAXPATHLEN);
+
+        buffer_free(&buffer);
+        return file;
+}
+
+char *
+authorized_keys_file(struct passwd *pw)
+{
+        return expand_filename(options.authorized_keys_file, pw);
+}
+
+char *
+authorized_keys_file2(struct passwd *pw)
+{
+        return expand_filename(options.authorized_keys_file2, pw);
+}
+
+/*
+ * Check a given file for security. This is defined as all components
+ * of the path to the file must either be owned by either the owner of
+ * of the file or root and no directories must be world writable.
+ *
+ * XXX Should any specific check be done for sym links ?
+ *
+ * Takes an open file descriptor, the file name, a uid and and
+ * error buffer plus max size as arguments.
+ *
+ * Returns 0 on success and -1 on failure
+ */
+int
+secure_filename(FILE *f, const char *file, uid_t uid, char *err, size_t errlen)
+{
+        char buf[MAXPATHLEN];
+        char *cp;
+        struct stat st;
+
+        if (realpath(file, buf) == NULL) {
+                snprintf(err, errlen, "realpath %s failed: %s", file,
+                    strerror(errno));
+                return -1;
+        }
+
+        /* check the open file to avoid races */
+        if (fstat(fileno(f), &st) < 0 ||
+            (st.st_uid != 0 && st.st_uid != uid) ||
+            (st.st_mode & 022) != 0) {
+                snprintf(err, errlen, "bad ownership or modes for file %s",
+                    buf);
+                return -1;
+        }
+
+        /* for each component of the canonical path, walking upwards */
+        for (;;) {
+                if ((cp = dirname(buf)) == NULL) {
+                        snprintf(err, errlen, "dirname() failed");
+                        return -1;
+                }
+                strlcpy(buf, cp, sizeof(buf));
+
+                debug3("secure_filename: checking '%s'", buf);
+                if (stat(buf, &st) < 0 ||
+                    (st.st_uid != 0 && st.st_uid != uid) ||
+                    (st.st_mode & 022) != 0) {
+                        snprintf(err, errlen, 
+                            "bad ownership or modes for directory %s", buf);
+                        return -1;
+                }
+
+                /*
+                 * dirname should always complete with a "/" path,
+                 * but we can be paranoid and check for "." too
+                 */
+                if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0))
+                        break;
+        }
+        return 0;
+}
diff --git a/auth.h b/auth.h
index 20c3ebb78..2d1f1e9b9 100644
--- a/auth.h
+++ b/auth.h
@@ -21,7 +21,7 @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
- * $OpenBSD: auth.h,v 1.16 2001/05/18 14:13:28 markus Exp $
+ * $OpenBSD: auth.h,v 1.17 2001/05/20 17:20:35 markus Exp $
  */
 #ifndef AUTH_H
 #define AUTH_H
@@ -159,6 +159,16 @@ int	verify_response(Authctxt *authctxt, const char *response);
 
 struct passwd * auth_get_user(void);
 
+
+/* expand a filename - return buffer is allocated by xmalloc */
+char    *expand_filename(const char *template, struct passwd *pw);
+char    *authorized_keys_file(struct passwd *pw);
+char    *authorized_keys_file2(struct passwd *pw);
+
+/* check a file and the path to it */
+int
+secure_filename(FILE *f, const char *file, uid_t u, char *err, size_t errlen);
+
 #define AUTH_FAIL_MAX 6
 #define AUTH_FAIL_LOG (AUTH_FAIL_MAX/2)
 #define AUTH_FAIL_MSG "Too many authentication failures for %.100s"
diff --git a/auth2.c b/auth2.c
index e800c0587..9988f7aef 100644
--- a/auth2.c
+++ b/auth2.c
@@ -23,7 +23,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: auth2.c,v 1.57 2001/05/18 14:13:28 markus Exp $");
+RCSID("$OpenBSD: auth2.c,v 1.58 2001/05/20 17:20:35 markus Exp $");
 
 #include <openssl/evp.h>
 
@@ -666,7 +666,7 @@ authmethod_lookup(const char *name)
 int
 user_key_allowed(struct passwd *pw, Key *key)
 {
-        char line[8192], file[MAXPATHLEN];
+        char line[8192], *file;
         int found_key = 0;
         FILE *f;
         u_long linenum = 0;
@@ -680,13 +680,14 @@ user_key_allowed(struct passwd *pw, Key *key)
         temporarily_use_uid(pw);
 
         /* The authorized keys. */
-        snprintf(file, sizeof file, "%.500s/%.100s", pw->pw_dir,
-            _PATH_SSH_USER_PERMITTED_KEYS2);
+        file = authorized_keys_file2(pw);
+        debug("trying public key file %s", file);
 
         /* Fail quietly if file does not exist */
         if (stat(file, &st) < 0) {
                 /* Restore the privileged uid. */
                 restore_uid();
+                xfree(file);
                 return 0;
         }
         /* Open the file containing the authorized keys. */
@@ -694,48 +695,18 @@ user_key_allowed(struct passwd *pw, Key *key)
         if (!f) {
                 /* Restore the privileged uid. */
                 restore_uid();
+                xfree(file);
                 return 0;
         }
-        if (options.strict_modes) {
-                int fail = 0;
-                char buf[1024];
-                /* Check open file in order to avoid open/stat races */
-                if (fstat(fileno(f), &st) < 0 ||
-                    (st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
-                    (st.st_mode & 022) != 0) {
-                        snprintf(buf, sizeof buf,
-                            "%s authentication refused for %.100s: "
-                            "bad ownership or modes for '%s'.",
-                            key_type(key), pw->pw_name, file);
-                        fail = 1;
-                } else {
-                        /* Check path to _PATH_SSH_USER_PERMITTED_KEYS */
-                        int i;
-                        static const char *check[] = {
-                                "", _PATH_SSH_USER_DIR, NULL
-                        };
-                        for (i = 0; check[i]; i++) {
-                                snprintf(line, sizeof line, "%.500s/%.100s",
-                                    pw->pw_dir, check[i]);
-                                if (stat(line, &st) < 0 ||
-                                    (st.st_uid != 0 && st.st_uid != pw->pw_uid) ||
-                                    (st.st_mode & 022) != 0) {
-                                        snprintf(buf, sizeof buf,
-                                            "%s authentication refused for %.100s: "
-                                            "bad ownership or modes for '%s'.",
-                                            key_type(key), pw->pw_name, line);
-                                        fail = 1;
-                                        break;
-                                }
-                        }
-                }
-                if (fail) {
-                        fclose(f);
-                        log("%s", buf);
-                        restore_uid();
-                        return 0;
-                }
+        if (options.strict_modes &&
+            secure_filename(f, file, pw->pw_uid, line, sizeof(line)) != 0) {
+                xfree(file);
+                fclose(f);
+                log("Authentication refused: %s", line);
+                restore_uid();
+                return 0;
         }
+
         found_key = 0;
         found = key_new(key->type);
 
@@ -778,6 +749,7 @@ user_key_allowed(struct passwd *pw, Key *key)
         }
         restore_uid();
         fclose(f);
+        xfree(file);
         key_free(found);
         if (!found_key)
                 debug2("key not found");
diff --git a/servconf.c b/servconf.c
index 2d10963c4..e357d77a4 100644
--- a/servconf.c
+++ b/servconf.c
@@ -10,7 +10,7 @@
  */
 
 #include "includes.h"
-RCSID("$OpenBSD: servconf.c,v 1.81 2001/05/19 19:43:57 stevesk Exp $");
+RCSID("$OpenBSD: servconf.c,v 1.82 2001/05/20 17:20:35 markus Exp $");
 
 #ifdef KRB4
 #include <krb.h>
@@ -101,6 +101,8 @@ initialize_server_options(ServerOptions *options)
         options->reverse_mapping_check = -1;
         options->client_alive_interval = -1;
         options->client_alive_count_max = -1;
+        options->authorized_keys_file = NULL;
+        options->authorized_keys_file2 = NULL;
         options->pam_authentication_via_kbd_int = -1;
 }
 
@@ -208,6 +210,10 @@ fill_default_server_options(ServerOptions *options)
                 options->client_alive_interval = 0;  
         if (options->client_alive_count_max == -1)
                 options->client_alive_count_max = 3;
+        if (options->authorized_keys_file == NULL)
+                options->authorized_keys_file = _PATH_SSH_USER_PERMITTED_KEYS;  
+        if (options->authorized_keys_file2 == NULL)
+                options->authorized_keys_file2 = _PATH_SSH_USER_PERMITTED_KEYS2;
         if (options->pam_authentication_via_kbd_int == -1)
                 options->pam_authentication_via_kbd_int = 0;
 }
@@ -235,7 +241,8 @@ typedef enum {
         sGatewayPorts, sPubkeyAuthentication, sXAuthLocation, sSubsystem, sMaxStartups,
         sBanner, sReverseMappingCheck, sHostbasedAuthentication,
         sHostbasedUsesNameFromPacketOnly, sClientAliveInterval, 
-        sClientAliveCountMax, sPAMAuthenticationViaKbdInt
+        sClientAliveCountMax, sAuthorizedKeysFile, sAuthorizedKeysFile2,
+        sPAMAuthenticationViaKbdInt
 } ServerOpCodes;
 
 /* Textual representation of the tokens. */
@@ -301,6 +308,8 @@ static struct {
         { "reversemappingcheck", sReverseMappingCheck },
         { "clientaliveinterval", sClientAliveInterval },
         { "clientalivecountmax", sClientAliveCountMax },
+        { "authorizedkeysfile", sAuthorizedKeysFile },
+        { "authorizedkeysfile2", sAuthorizedKeysFile2 },
         { "PAMAuthenticationViaKbdInt", sPAMAuthenticationViaKbdInt },
         { NULL, 0 }
 };
@@ -802,6 +811,18 @@ parse_flag:
                 case sBanner:
                         charptr = &options->banner;
                         goto parse_filename;
+                /*
+                 * These options can contain %X options expanded at
+                 * connect time, so that you can specify paths like:
+                 *
+                 * AuthorizedKeysFile   /etc/ssh_keys/%u
+                 */
+                case sAuthorizedKeysFile:
+                case sAuthorizedKeysFile2:
+                        charptr = (opcode == sAuthorizedKeysFile ) ?
+                            &options->authorized_keys_file :
+                            &options->authorized_keys_file2;
+                        goto parse_filename;
 
                 case sClientAliveInterval:
                         intptr = &options->client_alive_interval;
diff --git a/servconf.h b/servconf.h
index a319a5c69..2bf19fb3b 100644
--- a/servconf.h
+++ b/servconf.h
@@ -11,7 +11,7 @@
  * called by a name other than "ssh" or "Secure Shell".
  */
 
-/* RCSID("$OpenBSD: servconf.h,v 1.42 2001/05/18 14:13:29 markus Exp $"); */
+/* RCSID("$OpenBSD: servconf.h,v 1.43 2001/05/20 17:20:35 markus Exp $"); */
 
 #ifndef SERVCONF_H
 #define SERVCONF_H
@@ -124,6 +124,8 @@ typedef struct {
                                          * for this many intervals, above
                                          * diconnect the session 
                                          */
+        char   *authorized_keys_file;   /* File containing public RSA keys */ 
+        char   *authorized_keys_file2;  /* File containing public SSH2 keys */
         int     pam_authentication_via_kbd_int;
 }       ServerOptions;
 /*
diff --git a/sshd.8 b/sshd.8
index 02960b70b..a66dac54e 100644
--- a/sshd.8
+++ b/sshd.8
@@ -34,7 +34,7 @@
 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.\" $OpenBSD: sshd.8,v 1.124 2001/05/19 19:43:57 stevesk Exp $
+.\" $OpenBSD: sshd.8,v 1.125 2001/05/20 17:20:35 markus Exp $
 .Dd September 25, 1999
 .Dt SSHD 8
 .Os
@@ -331,6 +331,34 @@ wildcards in the patterns.
 Only user names are valid; a numerical user ID isn't recognized.
 By default login is allowed regardless of the user name.
 .Pp
+.It Cm AuthorizedKeysFile
+Specifies the file that contains the public RSA keys that can be used
+for RSA authentication in protocol version 1.
+.Cm AuthorizedKeysFile
+may contain tokens of the form %T which are substituted during connection
+set-up. The following tokens are defined; %% is replaces by a literal '%',
+%h is replaced by the home directory of the user being authenticated and
+%u is replaced by the username of that user.
+After expansion,
+.Cm AuthorizedKeysFile
+is taken to be an absolute path or one realtive to the user's home
+directory.
+The default is
+.Dq .ssh/authorized_keys
+.It Cm AuthorizedKeysFile2
+Specifies the file that contains the public keys that can be used
+for public key authentication in protocol version 2.
+.Cm AuthorizedKeysFile2
+may contain tokens of the form %T which are substituted during connection
+set-up. The following tokens are defined; %% is replaces by a literal '%',
+%h is replaced by the home directory of the user being authenticated and
+%u is replaced by the username of that user.
+After expansion,
+.Cm AuthorizedKeysFile2
+is taken to be an absolute path or one realtive to the user's home
+directory.
+The default is
+.Dq .ssh/authorized_keys2
 .It Cm Banner
 In some jurisdictions, sending a warning message before authentication
 may be relevant for getting legal protection.
@@ -883,15 +911,18 @@ authentication protocol and cookie in standard input.
 Runs user's shell or command.
 .El
 .Sh AUTHORIZED_KEYS FILE FORMAT
-The
 .Pa $HOME/.ssh/authorized_keys
-file lists the RSA keys that are
+is the default file that lists the RSA keys that are
 permitted for RSA authentication in protocol version 1.
-Similarly, the
+.Cm AuthorizedKeysFile
+may be used to specify an alternative file.
+Similarly,
 .Pa $HOME/.ssh/authorized_keys2
-file lists the DSA and RSA keys that are
+is the default file that lists the DSA and RSA keys that are
 permitted for public key authentication (PubkeyAuthentication)
 in protocol version 2.
+.Cm AuthorizedKeysFile2
+may be used to specify an alternative file.
 .Pp
 Each line of the file contains one
 key (empty lines and lines starting with a
diff --git a/sshd_config b/sshd_config
index 8c411e476..90df340a6 100644
--- a/sshd_config
+++ b/sshd_config
@@ -1,4 +1,4 @@
-#       $OpenBSD: sshd_config,v 1.38 2001/04/15 21:41:29 deraadt Exp $
+#       $OpenBSD: sshd_config,v 1.39 2001/05/20 17:20:36 markus Exp $
 
 # This sshd was compiled with PATH=/usr/bin:/bin:/usr/sbin:/sbin
 
@@ -41,6 +41,9 @@ RhostsRSAAuthentication no
 HostbasedAuthentication no
 #
 RSAAuthentication yes
+PubkeyAuthentication yes
+#AuthorizedKeysFile     %h/.ssh/authorized_keys
+#AuthorizedKeysFile2    %h/.ssh/authorized_keys2
 
 # To disable tunneled clear text passwords, change to no here!
 PasswordAuthentication yes