-/* $OpenBSD: auth.c,v 1.150 2020/12/20 23:36:51 djm Exp $ */
+/* $OpenBSD: auth.c,v 1.151 2020/12/22 00:12:22 djm Exp $ */
/*
* Copyright (c) 2000 Markus Friedl. All rights reserved.
*
}
}
-/*
- * Runs command in a subprocess with a minimal environment.
- * Returns pid on success, 0 on failure.
- * The child stdout and stderr maybe captured, left attached or sent to
- * /dev/null depending on the contents of flags.
- * "tag" is prepended to log messages.
- * NB. "command" is only used for logging; the actual command executed is
- * av[0].
- */
-pid_t
-subprocess(const char *tag, struct passwd *pw, const char *command,
- int ac, char **av, FILE **child, u_int flags)
-{
- FILE *f = NULL;
- struct stat st;
- int fd, devnull, p[2], i;
- pid_t pid;
- char *cp, errmsg[512];
- u_int envsize;
- char **child_env;
-
- if (child != NULL)
- *child = NULL;
-
- debug3_f("%s command \"%s\" running as %s (flags 0x%x)",
- tag, command, pw->pw_name, flags);
-
- /* Check consistency */
- if ((flags & SSH_SUBPROCESS_STDOUT_DISCARD) != 0 &&
- (flags & SSH_SUBPROCESS_STDOUT_CAPTURE) != 0) {
- error_f("inconsistent flags");
- return 0;
- }
- if (((flags & SSH_SUBPROCESS_STDOUT_CAPTURE) == 0) != (child == NULL)) {
- error_f("inconsistent flags/output");
- return 0;
- }
-
- /*
- * If executing an explicit binary, then verify the it exists
- * and appears safe-ish to execute
- */
- if (!path_absolute(av[0])) {
- error("%s path is not absolute", tag);
- return 0;
- }
- temporarily_use_uid(pw);
- if (stat(av[0], &st) == -1) {
- error("Could not stat %s \"%s\": %s", tag,
- av[0], strerror(errno));
- restore_uid();
- return 0;
- }
- if (safe_path(av[0], &st, NULL, 0, errmsg, sizeof(errmsg)) != 0) {
- error("Unsafe %s \"%s\": %s", tag, av[0], errmsg);
- restore_uid();
- return 0;
- }
- /* Prepare to keep the child's stdout if requested */
- if (pipe(p) == -1) {
- error("%s: pipe: %s", tag, strerror(errno));
- restore_uid();
- return 0;
- }
- restore_uid();
-
- switch ((pid = fork())) {
- case -1: /* error */
- error("%s: fork: %s", tag, strerror(errno));
- close(p[0]);
- close(p[1]);
- return 0;
- case 0: /* child */
- /* Prepare a minimal environment for the child. */
- envsize = 5;
- child_env = xcalloc(sizeof(*child_env), envsize);
- child_set_env(&child_env, &envsize, "PATH", _PATH_STDPATH);
- child_set_env(&child_env, &envsize, "USER", pw->pw_name);
- child_set_env(&child_env, &envsize, "LOGNAME", pw->pw_name);
- child_set_env(&child_env, &envsize, "HOME", pw->pw_dir);
- if ((cp = getenv("LANG")) != NULL)
- child_set_env(&child_env, &envsize, "LANG", cp);
-
- for (i = 0; i < NSIG; i++)
- ssh_signal(i, SIG_DFL);
-
- if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1) {
- error("%s: open %s: %s", tag, _PATH_DEVNULL,
- strerror(errno));
- _exit(1);
- }
- if (dup2(devnull, STDIN_FILENO) == -1) {
- error("%s: dup2: %s", tag, strerror(errno));
- _exit(1);
- }
-
- /* Set up stdout as requested; leave stderr in place for now. */
- fd = -1;
- if ((flags & SSH_SUBPROCESS_STDOUT_CAPTURE) != 0)
- fd = p[1];
- else if ((flags & SSH_SUBPROCESS_STDOUT_DISCARD) != 0)
- fd = devnull;
- if (fd != -1 && dup2(fd, STDOUT_FILENO) == -1) {
- error("%s: dup2: %s", tag, strerror(errno));
- _exit(1);
- }
- closefrom(STDERR_FILENO + 1);
-
- /* Don't use permanently_set_uid() here to avoid fatal() */
- if (setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) == -1) {
- error("%s: setresgid %u: %s", tag, (u_int)pw->pw_gid,
- strerror(errno));
- _exit(1);
- }
- if (setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid) == -1) {
- error("%s: setresuid %u: %s", tag, (u_int)pw->pw_uid,
- strerror(errno));
- _exit(1);
- }
- /* stdin is pointed to /dev/null at this point */
- if ((flags & SSH_SUBPROCESS_STDOUT_DISCARD) != 0 &&
- dup2(STDIN_FILENO, STDERR_FILENO) == -1) {
- error("%s: dup2: %s", tag, strerror(errno));
- _exit(1);
- }
-
- execve(av[0], av, child_env);
- error("%s exec \"%s\": %s", tag, command, strerror(errno));
- _exit(127);
- default: /* parent */
- break;
- }
-
- close(p[1]);
- if ((flags & SSH_SUBPROCESS_STDOUT_CAPTURE) == 0)
- close(p[0]);
- else if ((f = fdopen(p[0], "r")) == NULL) {
- error("%s: fdopen: %s", tag, strerror(errno));
- close(p[0]);
- /* Don't leave zombie child */
- kill(pid, SIGTERM);
- while (waitpid(pid, NULL, 0) == -1 && errno == EINTR)
- ;
- return 0;
- }
- /* Success */
- debug3_f("%s pid %ld", tag, (long)pid);
- if (child != NULL)
- *child = f;
- return pid;
-}
-
/* These functions link key/cert options to the auth framework */
/* Log sshauthopt options locally and (optionally) for remote transmission */
-/* $OpenBSD: auth.h,v 1.100 2019/09/06 05:23:55 djm Exp $ */
+/* $OpenBSD: auth.h,v 1.101 2020/12/22 00:12:22 djm Exp $ */
/*
* Copyright (c) 2000 Markus Friedl. All rights reserved.
struct passwd *fakepw(void);
-#define SSH_SUBPROCESS_STDOUT_DISCARD (1) /* Discard stdout */
-#define SSH_SUBPROCESS_STDOUT_CAPTURE (1<<1) /* Redirect stdout */
-#define SSH_SUBPROCESS_STDERR_DISCARD (1<<2) /* Discard stderr */
-pid_t subprocess(const char *, struct passwd *,
- const char *, int, char **, FILE **, u_int flags);
-
int sys_auth_passwd(struct ssh *, const char *);
#if defined(KRB5) && !defined(HEIMDAL)
-/* $OpenBSD: auth2-pubkey.c,v 1.102 2020/12/17 23:28:50 djm Exp $ */
+/* $OpenBSD: auth2-pubkey.c,v 1.103 2020/12/22 00:12:22 djm Exp $ */
/*
* Copyright (c) 2000 Markus Friedl. All rights reserved.
*
/* Prepare a printable command for logs, etc. */
command = argv_assemble(ac, av);
- if ((pid = subprocess("AuthorizedPrincipalsCommand", runas_pw, command,
+ if ((pid = subprocess("AuthorizedPrincipalsCommand", command,
ac, av, &f,
- SSH_SUBPROCESS_STDOUT_CAPTURE|SSH_SUBPROCESS_STDERR_DISCARD)) == 0)
+ SSH_SUBPROCESS_STDOUT_CAPTURE|SSH_SUBPROCESS_STDERR_DISCARD,
+ runas_pw, temporarily_use_uid, restore_uid)) == 0)
goto out;
uid_swapped = 1;
xasprintf(&command, "%s %s", av[0], av[1]);
}
- if ((pid = subprocess("AuthorizedKeysCommand", runas_pw, command,
+ if ((pid = subprocess("AuthorizedKeysCommand", command,
ac, av, &f,
- SSH_SUBPROCESS_STDOUT_CAPTURE|SSH_SUBPROCESS_STDERR_DISCARD)) == 0)
+ SSH_SUBPROCESS_STDOUT_CAPTURE|SSH_SUBPROCESS_STDERR_DISCARD,
+ runas_pw, temporarily_use_uid, restore_uid)) == 0)
goto out;
uid_swapped = 1;
-/* $OpenBSD: misc.c,v 1.156 2020/11/27 00:49:58 djm Exp $ */
+/* $OpenBSD: misc.c,v 1.157 2020/12/22 00:12:22 djm Exp $ */
/*
* Copyright (c) 2000 Markus Friedl. All rights reserved.
* Copyright (c) 2005-2020 Damien Miller. All rights reserved.
close(devnull);
return ret;
}
+
+/*
+ * Runs command in a subprocess with a minimal environment.
+ * Returns pid on success, 0 on failure.
+ * The child stdout and stderr maybe captured, left attached or sent to
+ * /dev/null depending on the contents of flags.
+ * "tag" is prepended to log messages.
+ * NB. "command" is only used for logging; the actual command executed is
+ * av[0].
+ */
+pid_t
+subprocess(const char *tag, const char *command,
+ int ac, char **av, FILE **child, u_int flags,
+ struct passwd *pw, privdrop_fn *drop_privs, privrestore_fn *restore_privs)
+{
+ FILE *f = NULL;
+ struct stat st;
+ int fd, devnull, p[2], i;
+ pid_t pid;
+ char *cp, errmsg[512];
+ u_int nenv = 0;
+ char **env = NULL;
+
+ /* If dropping privs, then must specify user and restore function */
+ if (drop_privs != NULL && (pw == NULL || restore_privs == NULL)) {
+ error("%s: inconsistent arguments", tag); /* XXX fatal? */
+ return 0;
+ }
+ if (pw == NULL && (pw = getpwuid(getuid())) == NULL) {
+ error("%s: no user for current uid", tag);
+ return 0;
+ }
+ if (child != NULL)
+ *child = NULL;
+
+ debug3_f("%s command \"%s\" running as %s (flags 0x%x)",
+ tag, command, pw->pw_name, flags);
+
+ /* Check consistency */
+ if ((flags & SSH_SUBPROCESS_STDOUT_DISCARD) != 0 &&
+ (flags & SSH_SUBPROCESS_STDOUT_CAPTURE) != 0) {
+ error_f("inconsistent flags");
+ return 0;
+ }
+ if (((flags & SSH_SUBPROCESS_STDOUT_CAPTURE) == 0) != (child == NULL)) {
+ error_f("inconsistent flags/output");
+ return 0;
+ }
+
+ /*
+ * If executing an explicit binary, then verify the it exists
+ * and appears safe-ish to execute
+ */
+ if (!path_absolute(av[0])) {
+ error("%s path is not absolute", tag);
+ return 0;
+ }
+ if (drop_privs != NULL)
+ drop_privs(pw);
+ if (stat(av[0], &st) == -1) {
+ error("Could not stat %s \"%s\": %s", tag,
+ av[0], strerror(errno));
+ goto restore_return;
+ }
+ if ((flags & SSH_SUBPROCESS_UNSAFE_PATH) == 0 &&
+ safe_path(av[0], &st, NULL, 0, errmsg, sizeof(errmsg)) != 0) {
+ error("Unsafe %s \"%s\": %s", tag, av[0], errmsg);
+ goto restore_return;
+ }
+ /* Prepare to keep the child's stdout if requested */
+ if (pipe(p) == -1) {
+ error("%s: pipe: %s", tag, strerror(errno));
+ restore_return:
+ if (restore_privs != NULL)
+ restore_privs();
+ return 0;
+ }
+ if (restore_privs != NULL)
+ restore_privs();
+
+ switch ((pid = fork())) {
+ case -1: /* error */
+ error("%s: fork: %s", tag, strerror(errno));
+ close(p[0]);
+ close(p[1]);
+ return 0;
+ case 0: /* child */
+ /* Prepare a minimal environment for the child. */
+ if ((flags & SSH_SUBPROCESS_PRESERVE_ENV) == 0) {
+ nenv = 5;
+ env = xcalloc(sizeof(*env), nenv);
+ child_set_env(&env, &nenv, "PATH", _PATH_STDPATH);
+ child_set_env(&env, &nenv, "USER", pw->pw_name);
+ child_set_env(&env, &nenv, "LOGNAME", pw->pw_name);
+ child_set_env(&env, &nenv, "HOME", pw->pw_dir);
+ if ((cp = getenv("LANG")) != NULL)
+ child_set_env(&env, &nenv, "LANG", cp);
+ }
+
+ for (i = 0; i < NSIG; i++)
+ ssh_signal(i, SIG_DFL);
+
+ if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1) {
+ error("%s: open %s: %s", tag, _PATH_DEVNULL,
+ strerror(errno));
+ _exit(1);
+ }
+ if (dup2(devnull, STDIN_FILENO) == -1) {
+ error("%s: dup2: %s", tag, strerror(errno));
+ _exit(1);
+ }
+
+ /* Set up stdout as requested; leave stderr in place for now. */
+ fd = -1;
+ if ((flags & SSH_SUBPROCESS_STDOUT_CAPTURE) != 0)
+ fd = p[1];
+ else if ((flags & SSH_SUBPROCESS_STDOUT_DISCARD) != 0)
+ fd = devnull;
+ if (fd != -1 && dup2(fd, STDOUT_FILENO) == -1) {
+ error("%s: dup2: %s", tag, strerror(errno));
+ _exit(1);
+ }
+ closefrom(STDERR_FILENO + 1);
+
+ if (setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) == -1) {
+ error("%s: setresgid %u: %s", tag, (u_int)pw->pw_gid,
+ strerror(errno));
+ _exit(1);
+ }
+ if (setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid) == -1) {
+ error("%s: setresuid %u: %s", tag, (u_int)pw->pw_uid,
+ strerror(errno));
+ _exit(1);
+ }
+ /* stdin is pointed to /dev/null at this point */
+ if ((flags & SSH_SUBPROCESS_STDOUT_DISCARD) != 0 &&
+ dup2(STDIN_FILENO, STDERR_FILENO) == -1) {
+ error("%s: dup2: %s", tag, strerror(errno));
+ _exit(1);
+ }
+ if (env != NULL)
+ execve(av[0], av, env);
+ else
+ execv(av[0], av);
+ error("%s %s \"%s\": %s", tag, env == NULL ? "execv" : "execve",
+ command, strerror(errno));
+ _exit(127);
+ default: /* parent */
+ break;
+ }
+
+ close(p[1]);
+ if ((flags & SSH_SUBPROCESS_STDOUT_CAPTURE) == 0)
+ close(p[0]);
+ else if ((f = fdopen(p[0], "r")) == NULL) {
+ error("%s: fdopen: %s", tag, strerror(errno));
+ close(p[0]);
+ /* Don't leave zombie child */
+ kill(pid, SIGTERM);
+ while (waitpid(pid, NULL, 0) == -1 && errno == EINTR)
+ ;
+ return 0;
+ }
+ /* Success */
+ debug3_f("%s pid %ld", tag, (long)pid);
+ if (child != NULL)
+ *child = f;
+ return pid;
+}
-/* $OpenBSD: misc.h,v 1.90 2020/11/27 00:49:58 djm Exp $ */
+/* $OpenBSD: misc.h,v 1.91 2020/12/22 00:12:22 djm Exp $ */
/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
struct passwd *pwcopy(struct passwd *);
const char *ssh_gai_strerror(int);
+typedef void privdrop_fn(struct passwd *);
+typedef void privrestore_fn(void);
+#define SSH_SUBPROCESS_STDOUT_DISCARD (1) /* Discard stdout */
+#define SSH_SUBPROCESS_STDOUT_CAPTURE (1<<1) /* Redirect stdout */
+#define SSH_SUBPROCESS_STDERR_DISCARD (1<<2) /* Discard stderr */
+#define SSH_SUBPROCESS_UNSAFE_PATH (1<<3) /* Don't check for safe cmd */
+#define SSH_SUBPROCESS_PRESERVE_ENV (1<<4) /* Keep parent environment */
+pid_t subprocess(const char *, const char *, int, char **, FILE **, u_int,
+ struct passwd *, privdrop_fn *, privrestore_fn *);
+
typedef struct arglist arglist;
struct arglist {
char **list;
projects / thirdparty / openssh-portable.git / commitdiff
