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diff -ruN openssh-5.5p1.orig/auth2-pubkey.c openssh-5.5p1/auth2-pubkey.c
--- openssh-5.5p1.orig/auth2-pubkey.c 2010-03-21 14:51:21.000000000 -0400
+++ openssh-5.5p1/auth2-pubkey.c 2010-07-03 20:23:43.000000000 -0400
@@ -27,6 +27,7 @@
#include <sys/types.h>
#include <sys/stat.h>
+#include <sys/wait.h>
#include <fcntl.h>
#include <pwd.h>
@@ -178,27 +178,15 @@
/* return 1 if user allows given key */
static int
-user_key_allowed2(struct passwd *pw, Key *key, char *file)
+user_search_key_in_file(FILE *f, char *file, Key* key, struct passwd *pw)
{
char line[SSH_MAX_PUBKEY_BYTES];
const char *reason;
int found_key = 0;
- FILE *f;
u_long linenum = 0;
Key *found;
char *fp;
- /* Temporarily use the user's uid. */
- temporarily_use_uid(pw);
-
- debug("trying public key file %s", file);
- f = auth_openkeyfile(file, pw, options.strict_modes);
-
- if (!f) {
- restore_uid();
- return 0;
- }
-
found_key = 0;
found = key_new(key_is_cert(key) ? KEY_UNSPEC : key->type);
@@ -273,8 +261,6 @@
break;
}
}
- restore_uid();
- fclose(f);
key_free(found);
if (!found_key)
debug2("key not found");
@@ -321,13 +307,191 @@
return ret;
}
-/* check whether given key is in .ssh/authorized_keys* */
+/* return 1 if user allows given key */
+static int
+user_key_allowed2(struct passwd *pw, Key *key, char *file)
+{
+ FILE *f;
+ int found_key = 0;
+
+ /* Temporarily use the user's uid. */
+ temporarily_use_uid(pw);
+
+ debug("trying public key file %s", file);
+ f = auth_openkeyfile(file, pw, options.strict_modes);
+
+ if (f) {
+ found_key = user_search_key_in_file (f, file, key, pw);
+ fclose(f);
+ }
+
+ restore_uid();
+ return found_key;
+}
+
+#ifdef WITH_AUTHORIZED_KEYS_COMMAND
+
+#define WHITESPACE " \t\r\n"
+
+/* return 1 if user allows given key */
+static int
+user_key_via_command_allowed2(struct passwd *pw, Key *key)
+{
+ FILE *f;
+ int found_key = 0;
+ char *progname = NULL;
+ char *cp;
+ struct passwd *runas_pw;
+ struct stat st;
+ int childdescriptors[2], i;
+ pid_t pstat, pid, child;
+
+ if (options.authorized_keys_command == NULL || options.authorized_keys_command[0] != '/')
+ return -1;
+
+ /* get the run as identity from config */
+ runas_pw = (options.authorized_keys_command_runas == NULL)? pw
+ : getpwnam (options.authorized_keys_command_runas);
+ if (!runas_pw) {
+ error("%s: getpwnam(\"%s\"): %s", __func__,
+ options.authorized_keys_command_runas, strerror(errno));
+ return 0;
+ }
+
+ /* Temporarily use the specified uid. */
+ if (runas_pw->pw_uid != 0)
+ temporarily_use_uid(runas_pw);
+
+ progname = xstrdup(options.authorized_keys_command);
+
+ debug3("%s: checking program '%s'", __func__, progname);
+
+ if (stat (progname, &st) < 0) {
+ error("%s: stat(\"%s\"): %s", __func__,
+ progname, strerror(errno));
+ goto go_away;
+ }
+
+ if (st.st_uid != 0 || (st.st_mode & 022) != 0) {
+ error("bad ownership or modes for AuthorizedKeysCommand \"%s\"",
+ progname);
+ goto go_away;
+ }
+
+ if (!S_ISREG(st.st_mode)) {
+ error("AuthorizedKeysCommand \"%s\" is not a regular file",
+ progname);
+ goto go_away;
+ }
+
+ /*
+ * Descend the path, checking that each component is a
+ * root-owned directory with strict permissions.
+ */
+ do {
+ if ((cp = strrchr(progname, '/')) == NULL)
+ break;
+ else
+ *cp = '\0';
+
+ debug3("%s: checking component '%s'", __func__, (*progname == '\0' ? "/" : progname));
+
+ if (stat((*progname == '\0' ? "/" : progname), &st) != 0) {
+ error("%s: stat(\"%s\"): %s", __func__,
+ progname, strerror(errno));
+ goto go_away;
+ }
+ if (st.st_uid != 0 || (st.st_mode & 022) != 0) {
+ error("bad ownership or modes for AuthorizedKeysCommand path component \"%s\"",
+ progname);
+ goto go_away;
+ }
+ if (!S_ISDIR(st.st_mode)) {
+ error("AuthorizedKeysCommand path component \"%s\" is not a directory",
+ progname);
+ goto go_away;
+ }
+ } while (1);
+
+ /* open the pipe and read the keys */
+ if (pipe(childdescriptors)) {
+ error("failed to pipe(2) for AuthorizedKeysCommand: %s",
+ strerror(errno));
+ goto go_away;
+ }
+
+ child = fork();
+ if (child == -1) {
+ error("failed to fork(2) for AuthorizedKeysCommand: %s",
+ strerror(errno));
+ goto go_away;
+ } else if (child == 0) {
+ /* we're in the child process here -- we should never return from this block. */
+ /* permanently drop privs in child process */
+ if (runas_pw->pw_uid != 0) {
+ restore_uid();
+ permanently_set_uid(runas_pw);
+ }
+
+ close(childdescriptors[0]);
+ /* put the write end of the pipe on stdout (FD 1) */
+ if (dup2(childdescriptors[1], 1) == -1) {
+ error("failed to dup2(2) from AuthorizedKeysCommand: %s",
+ strerror(errno));
+ _exit(127);
+ }
+
+ debug3("about to execl() AuthorizedKeysCommand: \"%s\" \"%s\"", options.authorized_keys_command, pw->pw_name);
+ /* see session.c:child_close_fds() */
+ for (i = 3; i < 64; ++i) {
+ close(i);
+ }
+
+ execl(options.authorized_keys_command, options.authorized_keys_command, pw->pw_name, NULL);
+
+ /* if we got here, it didn't work */
+ error("failed to execl AuthorizedKeysCommand: %s", strerror(errno)); /* this won't work because we closed the fds above */
+ _exit(127);
+ }
+
+ close(childdescriptors[1]);
+ f = fdopen(childdescriptors[0], "r");
+ if (!f) {
+ error("%s: could not buffer FDs from AuthorizedKeysCommand (\"%s\", \"r\"): %s", __func__,
+ options.authorized_keys_command, strerror (errno));
+ goto go_away;
+ }
+
+ found_key = user_search_key_in_file (f, options.authorized_keys_command, key, pw);
+ fclose (f);
+ do {
+ pid = waitpid(child, &pstat, 0);
+ } while (pid == -1 && errno == EINTR);
+
+ /* what about the return value from the child process? */
+go_away:
+ if (progname)
+ xfree (progname);
+
+ if (runas_pw->pw_uid != 0)
+ restore_uid();
+ return found_key;
+}
+#endif
+
+/* check whether given key is in <AuthorizedKeysCommand or .ssh/authorized_keys* */
int
user_key_allowed(struct passwd *pw, Key *key)
{
int success;
char *file;
+#ifdef WITH_AUTHORIZED_KEYS_COMMAND
+ success = user_key_via_command_allowed2(pw, key);
+ if (success > 0)
+ return success;
+#endif
+
if (auth_key_is_revoked(key))
return 0;
if (key_is_cert(key) && auth_key_is_revoked(key->cert->signature_key))
diff -ruN openssh-5.5p1.orig/configure.ac openssh-5.5p1/configure.ac
--- openssh-5.5p1.orig/configure.ac 2010-04-10 08:58:01.000000000 -0400
+++ openssh-5.5p1/configure.ac 2010-07-03 19:57:42.000000000 -0400
@@ -1346,6 +1346,18 @@
esac ]
)
+# Check whether user wants AuthorizedKeysCommand support
+AKC_MSG="no"
+AC_ARG_WITH(authorized-keys-command,
+ [ --with-authorized-keys-command Enable AuthorizedKeysCommand support],
+ [
+ if test "x$withval" != "xno" ; then
+ AC_DEFINE([WITH_AUTHORIZED_KEYS_COMMAND], 1, [Enable AuthorizedKeysCommand support])
+ AKC_MSG="yes"
+ fi
+ ]
+)
+
dnl Checks for library functions. Please keep in alphabetical order
AC_CHECK_FUNCS( \
arc4random \
@@ -4181,6 +4193,7 @@
echo " Smartcard support: $SCARD_MSG"
echo " S/KEY support: $SKEY_MSG"
echo " TCP Wrappers support: $TCPW_MSG"
+echo " AuthorizedKeysCommand support: $AKC_MSG"
echo " MD5 password support: $MD5_MSG"
echo " libedit support: $LIBEDIT_MSG"
echo " Solaris process contract support: $SPC_MSG"
diff -ruN openssh-5.5p1.orig/servconf.c openssh-5.5p1/servconf.c
--- openssh-5.5p1.orig/servconf.c 2010-03-25 19:40:04.000000000 -0400
+++ openssh-5.5p1/servconf.c 2010-07-03 19:59:07.000000000 -0400
@@ -128,6 +128,8 @@
options->num_permitted_opens = -1;
options->adm_forced_command = NULL;
options->chroot_directory = NULL;
+ options->authorized_keys_command = NULL;
+ options->authorized_keys_command_runas = NULL;
options->zero_knowledge_password_authentication = -1;
options->revoked_keys_file = NULL;
options->trusted_user_ca_keys = NULL;
@@ -311,6 +313,7 @@
sUsePrivilegeSeparation, sAllowAgentForwarding,
sZeroKnowledgePasswordAuthentication, sHostCertificate,
sRevokedKeys, sTrustedUserCAKeys,
+ sAuthorizedKeysCommand, sAuthorizedKeysCommandRunAs,
sDeprecated, sUnsupported
} ServerOpCodes;
@@ -432,6 +435,13 @@
{ "hostcertificate", sHostCertificate, SSHCFG_GLOBAL },
{ "revokedkeys", sRevokedKeys, SSHCFG_ALL },
{ "trustedusercakeys", sTrustedUserCAKeys, SSHCFG_ALL },
+#ifdef WITH_AUTHORIZED_KEYS_COMMAND
+ { "authorizedkeyscommand", sAuthorizedKeysCommand, SSHCFG_ALL },
+ { "authorizedkeyscommandrunas", sAuthorizedKeysCommandRunAs, SSHCFG_ALL },
+#else
+ { "authorizedkeyscommand", sUnsupported, SSHCFG_ALL },
+ { "authorizedkeyscommandrunas", sUnsupported, SSHCFG_ALL },
+#endif
{ NULL, sBadOption, 0 }
};
@@ -1345,6 +1355,20 @@
charptr = &options->revoked_keys_file;
goto parse_filename;
+ case sAuthorizedKeysCommand:
+ len = strspn(cp, WHITESPACE);
+ if (*activep && options->authorized_keys_command == NULL)
+ options->authorized_keys_command = xstrdup(cp + len);
+ return 0;
+
+ case sAuthorizedKeysCommandRunAs:
+ charptr = &options->authorized_keys_command_runas;
+
+ arg = strdelim(&cp);
+ if (*activep && *charptr == NULL)
+ *charptr = xstrdup(arg);
+ break;
+
case sDeprecated:
logit("%s line %d: Deprecated option %s",
filename, linenum, arg);
@@ -1438,6 +1462,8 @@
M_CP_INTOPT(gss_authentication);
M_CP_INTOPT(rsa_authentication);
M_CP_INTOPT(pubkey_authentication);
+ M_CP_STROPT(authorized_keys_command);
+ M_CP_STROPT(authorized_keys_command_runas);
M_CP_INTOPT(kerberos_authentication);
M_CP_INTOPT(hostbased_authentication);
M_CP_INTOPT(kbd_interactive_authentication);
@@ -1682,6 +1708,8 @@
dump_cfg_string(sChrootDirectory, o->chroot_directory);
dump_cfg_string(sTrustedUserCAKeys, o->trusted_user_ca_keys);
dump_cfg_string(sRevokedKeys, o->revoked_keys_file);
+ dump_cfg_string(sAuthorizedKeysCommand, o->authorized_keys_command);
+ dump_cfg_string(sAuthorizedKeysCommandRunAs, o->authorized_keys_command_runas);
/* string arguments requiring a lookup */
dump_cfg_string(sLogLevel, log_level_name(o->log_level));
diff -ruN openssh-5.5p1.orig/servconf.h openssh-5.5p1/servconf.h
--- openssh-5.5p1.orig/servconf.h 2010-03-04 05:53:35.000000000 -0500
+++ openssh-5.5p1/servconf.h 2010-07-03 19:57:42.000000000 -0400
@@ -156,6 +156,8 @@
char *chroot_directory;
char *revoked_keys_file;
char *trusted_user_ca_keys;
+ char *authorized_keys_command;
+ char *authorized_keys_command_runas;
} ServerOptions;
void initialize_server_options(ServerOptions *);
diff -ruN openssh-5.5p1.orig/sshd_config openssh-5.5p1/sshd_config
--- openssh-5.5p1.orig/sshd_config 2009-10-11 06:51:09.000000000 -0400
+++ openssh-5.5p1/sshd_config 2010-07-03 19:57:42.000000000 -0400
@@ -44,6 +44,8 @@
#RSAAuthentication yes
#PubkeyAuthentication yes
#AuthorizedKeysFile .ssh/authorized_keys
+#AuthorizedKeysCommand none
+#AuthorizedKeysCommandRunAs nobody
# For this to work you will also need host keys in /etc/ssh/ssh_known_hosts
#RhostsRSAAuthentication no
diff -ruN openssh-5.5p1.orig/sshd_config.0 openssh-5.5p1/sshd_config.0
--- openssh-5.5p1.orig/sshd_config.0 2010-04-15 20:17:12.000000000 -0400
+++ openssh-5.5p1/sshd_config.0 2010-07-03 19:57:42.000000000 -0400
@@ -352,7 +352,8 @@
KbdInteractiveAuthentication, KerberosAuthentication,
MaxAuthTries, MaxSessions, PasswordAuthentication,
PermitEmptyPasswords, PermitOpen, PermitRootLogin,
- PubkeyAuthentication, RhostsRSAAuthentication, RSAAuthentication,
+ PubkeyAuthentication, AuthorizedKeysCommand, AuthorizedKeysCommandRunAs,
+ RhostsRSAAuthentication, RSAAuthentication,
X11DisplayOffset, X11Forwarding and X11UseLocalHost.
MaxAuthTries
@@ -467,6 +468,23 @@
this file is not readable, then public key authentication will be
refused for all users.
+ AuthorizedKeysCommand
+
+ Specifies a program to be used for lookup of the user's
+ public keys. The program will be invoked with its first
+ argument the name of the user being authorized, and should produce
+ on standard output AuthorizedKeys lines (see AUTHORIZED_KEYS
+ in sshd(8)). By default (or when set to the empty string) there is no
+ AuthorizedKeysCommand run. If the AuthorizedKeysCommand does not successfully
+ authorize the user, authorization falls through to the
+ AuthorizedKeysFile. Note that this option has an effect
+ only with PubkeyAuthentication turned on.
+
+ AuthorizedKeysCommandRunAs
+ Specifies the user under whose account the AuthorizedKeysCommand is run.
+ Empty string (the default value) means the user being authorized
+ is used.
+
RhostsRSAAuthentication
Specifies whether rhosts or /etc/hosts.equiv authentication to-
gether with successful RSA host authentication is allowed. The
diff -ruN openssh-5.5p1.orig/sshd_config.5 openssh-5.5p1/sshd_config.5
--- openssh-5.5p1.orig/sshd_config.5 2010-03-04 18:41:45.000000000 -0500
+++ openssh-5.5p1/sshd_config.5 2010-07-03 19:57:42.000000000 -0400
@@ -618,6 +618,9 @@
.Cm KerberosAuthentication ,
.Cm MaxAuthTries ,
.Cm MaxSessions ,
+.Cm PubkeyAuthentication ,
+.Cm AuthorizedKeysCommand ,
+.Cm AuthorizedKeysCommandRunAs ,
.Cm PasswordAuthentication ,
.Cm PermitEmptyPasswords ,
.Cm PermitOpen ,
@@ -819,6 +822,20 @@
Keys listed in this file will be refused for public key authentication.
Note that if this file is not readable, then public key authentication will
be refused for all users.
+.It Cm AuthorizedKeysCommand
+Specifies a program to be used for lookup of the user's
+public keys. The program will be invoked with its first
+argument the name of the user being authorized, and should produce
+on standard output AuthorizedKeys lines (see AUTHORIZED_KEYS
+in sshd(8)). By default (or when set to the empty string) there is no
+AuthorizedKeysCommand run. If the AuthorizedKeysCommand does not successfully
+authorize the user, authorization falls through to the
+AuthorizedKeysFile. Note that this option has an effect
+only with PubkeyAuthentication turned on.
+.It Cm AuthorizedKeysCommandRunAs
+Specifies the user under whose account the AuthorizedKeysCommand is run. Empty
+string (the default value) means the user being authorized is used.
+.Dq
.It Cm RhostsRSAAuthentication
Specifies whether rhosts or /etc/hosts.equiv authentication together
with successful RSA host authentication is allowed.
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