448 lines
15 KiB
Diff
448 lines
15 KiB
Diff
diff -up openssh-5.6p1/auth2-pubkey.c.akc openssh-5.6p1/auth2-pubkey.c
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--- openssh-5.6p1/auth2-pubkey.c.akc 2010-09-03 15:24:51.000000000 +0200
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+++ openssh-5.6p1/auth2-pubkey.c 2010-09-03 15:24:51.000000000 +0200
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@@ -27,6 +27,7 @@
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#include <sys/types.h>
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#include <sys/stat.h>
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+#include <sys/wait.h>
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#include <fcntl.h>
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#include <pwd.h>
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@@ -264,27 +265,15 @@ match_principals_file(char *file, struct
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/* return 1 if user allows given key */
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static int
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-user_key_allowed2(struct passwd *pw, Key *key, char *file)
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+user_search_key_in_file(FILE *f, char *file, Key* key, struct passwd *pw)
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{
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char line[SSH_MAX_PUBKEY_BYTES];
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const char *reason;
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int found_key = 0;
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- FILE *f;
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u_long linenum = 0;
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Key *found;
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char *fp;
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- /* Temporarily use the user's uid. */
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- temporarily_use_uid(pw);
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-
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- debug("trying public key file %s", file);
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- f = auth_openkeyfile(file, pw, options.strict_modes);
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-
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- if (!f) {
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- restore_uid();
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- return 0;
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- }
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-
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found_key = 0;
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found = key_new(key_is_cert(key) ? KEY_UNSPEC : key->type);
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@@ -377,8 +366,6 @@ user_key_allowed2(struct passwd *pw, Key
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break;
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}
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}
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- restore_uid();
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- fclose(f);
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key_free(found);
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if (!found_key)
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debug2("key not found");
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@@ -440,13 +427,191 @@ user_cert_trusted_ca(struct passwd *pw,
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return ret;
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}
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-/* check whether given key is in .ssh/authorized_keys* */
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+/* return 1 if user allows given key */
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+static int
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+user_key_allowed2(struct passwd *pw, Key *key, char *file)
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+{
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+ FILE *f;
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+ int found_key = 0;
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+
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+ /* Temporarily use the user's uid. */
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+ temporarily_use_uid(pw);
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+
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+ debug("trying public key file %s", file);
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+ f = auth_openkeyfile(file, pw, options.strict_modes);
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+
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+ if (f) {
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+ found_key = user_search_key_in_file (f, file, key, pw);
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+ fclose(f);
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+ }
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+
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+ restore_uid();
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+ return found_key;
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+}
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+
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+#ifdef WITH_AUTHORIZED_KEYS_COMMAND
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+
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+#define WHITESPACE " \t\r\n"
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+
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+/* return 1 if user allows given key */
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+static int
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+user_key_via_command_allowed2(struct passwd *pw, Key *key)
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+{
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+ FILE *f;
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+ int found_key = 0;
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+ char *progname = NULL;
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+ char *cp;
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+ struct passwd *runas_pw;
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+ struct stat st;
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+ int childdescriptors[2], i;
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+ pid_t pstat, pid, child;
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+
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+ if (options.authorized_keys_command == NULL || options.authorized_keys_command[0] != '/')
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+ return -1;
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+
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+ /* get the run as identity from config */
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+ runas_pw = (options.authorized_keys_command_runas == NULL)? pw
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+ : getpwnam (options.authorized_keys_command_runas);
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+ if (!runas_pw) {
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+ error("%s: getpwnam(\"%s\"): %s", __func__,
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+ options.authorized_keys_command_runas, strerror(errno));
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+ return 0;
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+ }
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+
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+ /* Temporarily use the specified uid. */
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+ if (runas_pw->pw_uid != 0)
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+ temporarily_use_uid(runas_pw);
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+
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+ progname = xstrdup(options.authorized_keys_command);
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+
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+ debug3("%s: checking program '%s'", __func__, progname);
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+
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+ if (stat (progname, &st) < 0) {
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+ error("%s: stat(\"%s\"): %s", __func__,
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+ progname, strerror(errno));
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+ goto go_away;
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+ }
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+
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+ if (st.st_uid != 0 || (st.st_mode & 022) != 0) {
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+ error("bad ownership or modes for AuthorizedKeysCommand \"%s\"",
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+ progname);
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+ goto go_away;
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+ }
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+
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+ if (!S_ISREG(st.st_mode)) {
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+ error("AuthorizedKeysCommand \"%s\" is not a regular file",
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+ progname);
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+ goto go_away;
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+ }
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+
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+ /*
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+ * Descend the path, checking that each component is a
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+ * root-owned directory with strict permissions.
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+ */
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+ do {
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+ if ((cp = strrchr(progname, '/')) == NULL)
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+ break;
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+ else
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+ *cp = '\0';
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+
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+ debug3("%s: checking component '%s'", __func__, (*progname == '\0' ? "/" : progname));
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+
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+ if (stat((*progname == '\0' ? "/" : progname), &st) != 0) {
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+ error("%s: stat(\"%s\"): %s", __func__,
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+ progname, strerror(errno));
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+ goto go_away;
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+ }
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+ if (st.st_uid != 0 || (st.st_mode & 022) != 0) {
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+ error("bad ownership or modes for AuthorizedKeysCommand path component \"%s\"",
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+ progname);
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+ goto go_away;
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+ }
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+ if (!S_ISDIR(st.st_mode)) {
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+ error("AuthorizedKeysCommand path component \"%s\" is not a directory",
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+ progname);
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+ goto go_away;
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+ }
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+ } while (1);
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+
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+ /* open the pipe and read the keys */
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+ if (pipe(childdescriptors)) {
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+ error("failed to pipe(2) for AuthorizedKeysCommand: %s",
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+ strerror(errno));
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+ goto go_away;
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+ }
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+
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+ child = fork();
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+ if (child == -1) {
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+ error("failed to fork(2) for AuthorizedKeysCommand: %s",
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+ strerror(errno));
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+ goto go_away;
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+ } else if (child == 0) {
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+ /* we're in the child process here -- we should never return from this block. */
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+ /* permanently drop privs in child process */
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+ if (runas_pw->pw_uid != 0) {
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+ restore_uid();
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+ permanently_set_uid(runas_pw);
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+ }
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+
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+ close(childdescriptors[0]);
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+ /* put the write end of the pipe on stdout (FD 1) */
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+ if (dup2(childdescriptors[1], 1) == -1) {
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+ error("failed to dup2(2) from AuthorizedKeysCommand: %s",
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+ strerror(errno));
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+ _exit(127);
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+ }
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+
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+ debug3("about to execl() AuthorizedKeysCommand: \"%s\" \"%s\"", options.authorized_keys_command, pw->pw_name);
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+ /* see session.c:child_close_fds() */
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+ for (i = 3; i < 64; ++i) {
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+ close(i);
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+ }
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+
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+ execl(options.authorized_keys_command, options.authorized_keys_command, pw->pw_name, NULL);
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+
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+ /* if we got here, it didn't work */
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+ error("failed to execl AuthorizedKeysCommand: %s", strerror(errno)); /* this won't work because we closed the fds above */
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+ _exit(127);
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+ }
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+
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+ close(childdescriptors[1]);
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+ f = fdopen(childdescriptors[0], "r");
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+ if (!f) {
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+ error("%s: could not buffer FDs from AuthorizedKeysCommand (\"%s\", \"r\"): %s", __func__,
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+ options.authorized_keys_command, strerror (errno));
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+ goto go_away;
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+ }
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+
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+ found_key = user_search_key_in_file (f, options.authorized_keys_command, key, pw);
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+ fclose (f);
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+ do {
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+ pid = waitpid(child, &pstat, 0);
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+ } while (pid == -1 && errno == EINTR);
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+
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+ /* what about the return value from the child process? */
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+go_away:
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+ if (progname)
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+ xfree (progname);
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+
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+ if (runas_pw->pw_uid != 0)
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+ restore_uid();
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+ return found_key;
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+}
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+#endif
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+
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+/* check whether given key is in <AuthorizedKeysCommand or .ssh/authorized_keys* */
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int
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user_key_allowed(struct passwd *pw, Key *key)
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{
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int success;
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char *file;
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+#ifdef WITH_AUTHORIZED_KEYS_COMMAND
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+ success = user_key_via_command_allowed2(pw, key);
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+ if (success > 0)
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+ return success;
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+#endif
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+
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if (auth_key_is_revoked(key))
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return 0;
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if (key_is_cert(key) && auth_key_is_revoked(key->cert->signature_key))
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diff -up openssh-5.6p1/configure.ac.akc openssh-5.6p1/configure.ac
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--- openssh-5.6p1/configure.ac.akc 2010-09-03 15:24:51.000000000 +0200
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+++ openssh-5.6p1/configure.ac 2010-09-03 15:24:51.000000000 +0200
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@@ -1346,6 +1346,18 @@ AC_ARG_WITH(audit,
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esac ]
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)
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+# Check whether user wants AuthorizedKeysCommand support
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+AKC_MSG="no"
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+AC_ARG_WITH(authorized-keys-command,
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+ [ --with-authorized-keys-command Enable AuthorizedKeysCommand support],
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+ [
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+ if test "x$withval" != "xno" ; then
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+ AC_DEFINE([WITH_AUTHORIZED_KEYS_COMMAND], 1, [Enable AuthorizedKeysCommand support])
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+ AKC_MSG="yes"
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+ fi
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+ ]
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+)
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+
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dnl Checks for library functions. Please keep in alphabetical order
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AC_CHECK_FUNCS( \
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arc4random \
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@@ -4209,6 +4221,7 @@ echo " Linux audit support
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echo " Smartcard support: $SCARD_MSG"
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echo " S/KEY support: $SKEY_MSG"
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echo " TCP Wrappers support: $TCPW_MSG"
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+echo " AuthorizedKeysCommand support: $AKC_MSG"
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echo " MD5 password support: $MD5_MSG"
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echo " libedit support: $LIBEDIT_MSG"
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echo " Solaris process contract support: $SPC_MSG"
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diff -up openssh-5.6p1/servconf.c.akc openssh-5.6p1/servconf.c
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--- openssh-5.6p1/servconf.c.akc 2010-09-03 15:24:50.000000000 +0200
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+++ openssh-5.6p1/servconf.c 2010-09-03 15:24:51.000000000 +0200
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@@ -129,6 +129,8 @@ initialize_server_options(ServerOptions
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options->num_permitted_opens = -1;
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options->adm_forced_command = NULL;
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options->chroot_directory = NULL;
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+ options->authorized_keys_command = NULL;
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+ options->authorized_keys_command_runas = NULL;
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options->zero_knowledge_password_authentication = -1;
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options->revoked_keys_file = NULL;
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options->trusted_user_ca_keys = NULL;
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@@ -316,6 +318,7 @@ typedef enum {
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sUsePrivilegeSeparation, sAllowAgentForwarding,
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sZeroKnowledgePasswordAuthentication, sHostCertificate,
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sRevokedKeys, sTrustedUserCAKeys, sAuthorizedPrincipalsFile,
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+ sAuthorizedKeysCommand, sAuthorizedKeysCommandRunAs,
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sDeprecated, sUnsupported
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} ServerOpCodes;
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@@ -439,6 +442,13 @@ static struct {
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{ "revokedkeys", sRevokedKeys, SSHCFG_ALL },
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{ "trustedusercakeys", sTrustedUserCAKeys, SSHCFG_ALL },
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{ "authorizedprincipalsfile", sAuthorizedPrincipalsFile, SSHCFG_ALL },
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+#ifdef WITH_AUTHORIZED_KEYS_COMMAND
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+ { "authorizedkeyscommand", sAuthorizedKeysCommand, SSHCFG_ALL },
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+ { "authorizedkeyscommandrunas", sAuthorizedKeysCommandRunAs, SSHCFG_ALL },
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+#else
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+ { "authorizedkeyscommand", sUnsupported, SSHCFG_ALL },
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+ { "authorizedkeyscommandrunas", sUnsupported, SSHCFG_ALL },
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+#endif
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{ NULL, sBadOption, 0 }
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};
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@@ -1360,6 +1370,20 @@ process_server_config_line(ServerOptions
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charptr = &options->revoked_keys_file;
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goto parse_filename;
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+ case sAuthorizedKeysCommand:
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+ len = strspn(cp, WHITESPACE);
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+ if (*activep && options->authorized_keys_command == NULL)
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+ options->authorized_keys_command = xstrdup(cp + len);
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+ return 0;
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+
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+ case sAuthorizedKeysCommandRunAs:
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+ charptr = &options->authorized_keys_command_runas;
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+
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+ arg = strdelim(&cp);
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+ if (*activep && *charptr == NULL)
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+ *charptr = xstrdup(arg);
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+ break;
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+
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case sDeprecated:
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logit("%s line %d: Deprecated option %s",
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filename, linenum, arg);
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@@ -1453,6 +1477,8 @@ copy_set_server_options(ServerOptions *d
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M_CP_INTOPT(gss_authentication);
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M_CP_INTOPT(rsa_authentication);
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M_CP_INTOPT(pubkey_authentication);
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+ M_CP_STROPT(authorized_keys_command);
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+ M_CP_STROPT(authorized_keys_command_runas);
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M_CP_INTOPT(kerberos_authentication);
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M_CP_INTOPT(hostbased_authentication);
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M_CP_INTOPT(hostbased_uses_name_from_packet_only);
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@@ -1705,6 +1731,8 @@ dump_config(ServerOptions *o)
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dump_cfg_string(sRevokedKeys, o->revoked_keys_file);
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dump_cfg_string(sAuthorizedPrincipalsFile,
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o->authorized_principals_file);
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+ dump_cfg_string(sAuthorizedKeysCommand, o->authorized_keys_command);
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+ dump_cfg_string(sAuthorizedKeysCommandRunAs, o->authorized_keys_command_runas);
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/* string arguments requiring a lookup */
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dump_cfg_string(sLogLevel, log_level_name(o->log_level));
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diff -up openssh-5.6p1/servconf.h.akc openssh-5.6p1/servconf.h
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--- openssh-5.6p1/servconf.h.akc 2010-09-03 15:24:50.000000000 +0200
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+++ openssh-5.6p1/servconf.h 2010-09-03 15:24:51.000000000 +0200
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@@ -158,6 +158,8 @@ typedef struct {
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char *revoked_keys_file;
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char *trusted_user_ca_keys;
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char *authorized_principals_file;
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+ char *authorized_keys_command;
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+ char *authorized_keys_command_runas;
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} ServerOptions;
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void initialize_server_options(ServerOptions *);
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diff -up openssh-5.6p1/sshd_config.0.akc openssh-5.6p1/sshd_config.0
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--- openssh-5.6p1/sshd_config.0.akc 2010-09-03 15:24:50.000000000 +0200
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+++ openssh-5.6p1/sshd_config.0 2010-09-03 15:27:26.000000000 +0200
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@@ -71,6 +71,23 @@ DESCRIPTION
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See PATTERNS in ssh_config(5) for more information on patterns.
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+ AuthorizedKeysCommand
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+
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+ Specifies a program to be used for lookup of the user's
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+ public keys. The program will be invoked with its first
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+ argument the name of the user being authorized, and should produce
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+ on standard output AuthorizedKeys lines (see AUTHORIZED_KEYS
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+ in sshd(8)). By default (or when set to the empty string) there is no
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+ AuthorizedKeysCommand run. If the AuthorizedKeysCommand does not successfully
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+ authorize the user, authorization falls through to the
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+ AuthorizedKeysFile. Note that this option has an effect
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+ only with PubkeyAuthentication turned on.
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+
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+ AuthorizedKeysCommandRunAs
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+ Specifies the user under whose account the AuthorizedKeysCommand is run.
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+ Empty string (the default value) means the user being authorized
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+ is used.
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+
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AuthorizedKeysFile
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Specifies the file that contains the public keys that can be used
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for user authentication. The format is described in the
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@@ -375,7 +392,8 @@ DESCRIPTION
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Only a subset of keywords may be used on the lines following a
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Match keyword. Available keywords are AllowAgentForwarding,
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- AllowTcpForwarding, AuthorizedKeysFile, AuthorizedPrincipalsFile,
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+ AllowTcpForwarding, AuthorizedKeysFile, AuthorizedKeysCommand,
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+ AuthorizedKeysCommandRunAs, AuthorizedPrincipalsFile,
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Banner, ChrootDirectory, ForceCommand, GatewayPorts,
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GSSAPIAuthentication, HostbasedAuthentication,
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HostbasedUsesNameFromPacketOnly, KbdInteractiveAuthentication,
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diff -up openssh-5.6p1/sshd_config.5.akc openssh-5.6p1/sshd_config.5
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--- openssh-5.6p1/sshd_config.5.akc 2010-09-03 15:24:50.000000000 +0200
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+++ openssh-5.6p1/sshd_config.5 2010-09-03 15:24:51.000000000 +0200
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@@ -654,6 +654,8 @@ Available keywords are
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.Cm AllowAgentForwarding ,
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.Cm AllowTcpForwarding ,
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.Cm AuthorizedKeysFile ,
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+.Cm AuthorizedKeysCommand ,
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+.Cm AuthorizedKeysCommandRunAs ,
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.Cm AuthorizedPrincipalsFile ,
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.Cm Banner ,
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.Cm ChrootDirectory ,
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@@ -666,6 +668,7 @@ Available keywords are
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.Cm KerberosAuthentication ,
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.Cm MaxAuthTries ,
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.Cm MaxSessions ,
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+.Cm PubkeyAuthentication ,
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.Cm PasswordAuthentication ,
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.Cm PermitEmptyPasswords ,
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.Cm PermitOpen ,
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@@ -868,6 +871,20 @@ Specifies a list of revoked public keys.
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Keys listed in this file will be refused for public key authentication.
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Note that if this file is not readable, then public key authentication will
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be refused for all users.
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+.It Cm AuthorizedKeysCommand
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+Specifies a program to be used for lookup of the user's
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+public keys. The program will be invoked with its first
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+argument the name of the user being authorized, and should produce
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+on standard output AuthorizedKeys lines (see AUTHORIZED_KEYS
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+in sshd(8)). By default (or when set to the empty string) there is no
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+AuthorizedKeysCommand run. If the AuthorizedKeysCommand does not successfully
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+authorize the user, authorization falls through to the
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+AuthorizedKeysFile. Note that this option has an effect
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+only with PubkeyAuthentication turned on.
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+.It Cm AuthorizedKeysCommandRunAs
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+Specifies the user under whose account the AuthorizedKeysCommand is run. Empty
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+string (the default value) means the user being authorized is used.
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+.Dq
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.It Cm RhostsRSAAuthentication
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Specifies whether rhosts or /etc/hosts.equiv authentication together
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with successful RSA host authentication is allowed.
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diff -up openssh-5.6p1/sshd_config.akc openssh-5.6p1/sshd_config
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--- openssh-5.6p1/sshd_config.akc 2010-09-03 15:24:50.000000000 +0200
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+++ openssh-5.6p1/sshd_config 2010-09-03 15:24:51.000000000 +0200
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@@ -45,6 +45,8 @@ SyslogFacility AUTHPRIV
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#RSAAuthentication yes
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#PubkeyAuthentication yes
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#AuthorizedKeysFile .ssh/authorized_keys
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+#AuthorizedKeysCommand none
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+#AuthorizedKeysCommandRunAs nobody
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# For this to work you will also need host keys in /etc/ssh/ssh_known_hosts
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#RhostsRSAAuthentication no
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