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upstream commit
Move several subprocess-related functions from various locations to misc.c. Extend subprocess() to offer a little more control over stdio disposition. feedback & ok dtucker@ Upstream-ID: 3573dd7109d13ef9bd3bed93a3deb170fbfce049
This commit is contained in:
djm@openbsd.org
Damien Miller
parent
643c2ad829
commit
de4ae07f12
99
auth.c
99
auth.c
@ -1,4 +1,4 @@
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/* $OpenBSD: auth.c,v 1.122 2017/06/24 06:34:38 djm Exp $ */
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/* $OpenBSD: auth.c,v 1.123 2017/08/18 05:36:45 djm Exp $ */
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/*
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* Copyright (c) 2000 Markus Friedl. All rights reserved.
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*
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@ -43,9 +43,6 @@
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#ifdef USE_SHADOW
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#include <shadow.h>
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#endif
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#ifdef HAVE_LIBGEN_H
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#include <libgen.h>
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#endif
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#include <stdarg.h>
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#include <stdio.h>
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#include <string.h>
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@ -498,98 +495,6 @@ check_key_in_hostfiles(struct passwd *pw, struct sshkey *key, const char *host,
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return host_status;
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}
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/*
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* Check a given path for security. This is defined as all components
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* of the path to the file must be owned by either the owner of
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* of the file or root and no directories must be group or world writable.
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*
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* XXX Should any specific check be done for sym links ?
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*
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* Takes a file name, its stat information (preferably from fstat() to
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* avoid races), the uid of the expected owner, their home directory and an
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* error buffer plus max size as arguments.
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*
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* Returns 0 on success and -1 on failure
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*/
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int
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auth_secure_path(const char *name, struct stat *stp, const char *pw_dir,
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uid_t uid, char *err, size_t errlen)
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{
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char buf[PATH_MAX], homedir[PATH_MAX];
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char *cp;
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int comparehome = 0;
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struct stat st;
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if (realpath(name, buf) == NULL) {
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snprintf(err, errlen, "realpath %s failed: %s", name,
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strerror(errno));
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return -1;
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}
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if (pw_dir != NULL && realpath(pw_dir, homedir) != NULL)
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comparehome = 1;
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if (!S_ISREG(stp->st_mode)) {
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snprintf(err, errlen, "%s is not a regular file", buf);
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return -1;
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}
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if ((!platform_sys_dir_uid(stp->st_uid) && stp->st_uid != uid) ||
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(stp->st_mode & 022) != 0) {
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snprintf(err, errlen, "bad ownership or modes for file %s",
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buf);
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return -1;
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}
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/* for each component of the canonical path, walking upwards */
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for (;;) {
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if ((cp = dirname(buf)) == NULL) {
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snprintf(err, errlen, "dirname() failed");
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return -1;
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}
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strlcpy(buf, cp, sizeof(buf));
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if (stat(buf, &st) < 0 ||
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(!platform_sys_dir_uid(st.st_uid) && st.st_uid != uid) ||
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(st.st_mode & 022) != 0) {
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snprintf(err, errlen,
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"bad ownership or modes for directory %s", buf);
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return -1;
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}
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/* If are past the homedir then we can stop */
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if (comparehome && strcmp(homedir, buf) == 0)
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break;
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/*
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* dirname should always complete with a "/" path,
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* but we can be paranoid and check for "." too
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*/
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if ((strcmp("/", buf) == 0) || (strcmp(".", buf) == 0))
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break;
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}
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return 0;
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}
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/*
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* Version of secure_path() that accepts an open file descriptor to
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* avoid races.
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*
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* Returns 0 on success and -1 on failure
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*/
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static int
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secure_filename(FILE *f, const char *file, struct passwd *pw,
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char *err, size_t errlen)
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{
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struct stat st;
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/* check the open file to avoid races */
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if (fstat(fileno(f), &st) < 0) {
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snprintf(err, errlen, "cannot stat file %s: %s",
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file, strerror(errno));
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return -1;
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}
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return auth_secure_path(file, &st, pw->pw_dir, pw->pw_uid, err, errlen);
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}
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static FILE *
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auth_openfile(const char *file, struct passwd *pw, int strict_modes,
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int log_missing, char *file_type)
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@ -622,7 +527,7 @@ auth_openfile(const char *file, struct passwd *pw, int strict_modes,
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return NULL;
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}
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if (strict_modes &&
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secure_filename(f, file, pw, line, sizeof(line)) != 0) {
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safe_path_fd(fileno(f), file, pw, line, sizeof(line)) != 0) {
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fclose(f);
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logit("Authentication refused: %s", line);
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auth_debug_add("Ignored %s: %s", file_type, line);
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6
auth.h
6
auth.h
@ -1,4 +1,4 @@
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/* $OpenBSD: auth.h,v 1.92 2017/06/24 06:34:38 djm Exp $ */
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/* $OpenBSD: auth.h,v 1.93 2017/08/18 05:36:45 djm Exp $ */
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/*
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* Copyright (c) 2000 Markus Friedl. All rights reserved.
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@ -146,10 +146,6 @@ void auth2_record_info(Authctxt *authctxt, const char *, ...)
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__attribute__((__nonnull__ (2)));
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void auth2_update_session_info(Authctxt *, const char *, const char *);
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struct stat;
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int auth_secure_path(const char *, struct stat *, const char *, uid_t,
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char *, size_t);
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#ifdef KRB5
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int auth_krb5(Authctxt *authctxt, krb5_data *auth, char **client, krb5_data *);
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int auth_krb5_tgt(Authctxt *authctxt, krb5_data *tgt);
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299
auth2-pubkey.c
299
auth2-pubkey.c
@ -1,4 +1,4 @@
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/* $OpenBSD: auth2-pubkey.c,v 1.68 2017/06/24 06:34:38 djm Exp $ */
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/* $OpenBSD: auth2-pubkey.c,v 1.69 2017/08/18 05:36:45 djm Exp $ */
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/*
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* Copyright (c) 2000 Markus Friedl. All rights reserved.
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*
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@ -27,7 +27,6 @@
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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 <errno.h>
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#include <fcntl.h>
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@ -242,288 +241,6 @@ done:
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return authenticated;
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}
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/*
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* Splits 's' into an argument vector. Handles quoted string and basic
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* escape characters (\\, \", \'). Caller must free the argument vector
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* and its members.
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*/
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static int
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split_argv(const char *s, int *argcp, char ***argvp)
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{
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int r = SSH_ERR_INTERNAL_ERROR;
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int argc = 0, quote, i, j;
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char *arg, **argv = xcalloc(1, sizeof(*argv));
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*argvp = NULL;
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*argcp = 0;
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for (i = 0; s[i] != '\0'; i++) {
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/* Skip leading whitespace */
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if (s[i] == ' ' || s[i] == '\t')
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continue;
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/* Start of a token */
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quote = 0;
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if (s[i] == '\\' &&
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(s[i + 1] == '\'' || s[i + 1] == '\"' || s[i + 1] == '\\'))
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i++;
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else if (s[i] == '\'' || s[i] == '"')
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quote = s[i++];
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argv = xreallocarray(argv, (argc + 2), sizeof(*argv));
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arg = argv[argc++] = xcalloc(1, strlen(s + i) + 1);
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argv[argc] = NULL;
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/* Copy the token in, removing escapes */
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for (j = 0; s[i] != '\0'; i++) {
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if (s[i] == '\\') {
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if (s[i + 1] == '\'' ||
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s[i + 1] == '\"' ||
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s[i + 1] == '\\') {
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i++; /* Skip '\' */
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arg[j++] = s[i];
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} else {
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/* Unrecognised escape */
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arg[j++] = s[i];
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}
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} else if (quote == 0 && (s[i] == ' ' || s[i] == '\t'))
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break; /* done */
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else if (quote != 0 && s[i] == quote)
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break; /* done */
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else
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arg[j++] = s[i];
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}
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if (s[i] == '\0') {
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if (quote != 0) {
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/* Ran out of string looking for close quote */
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r = SSH_ERR_INVALID_FORMAT;
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goto out;
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}
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break;
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}
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}
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/* Success */
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*argcp = argc;
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*argvp = argv;
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argc = 0;
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argv = NULL;
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r = 0;
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out:
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if (argc != 0 && argv != NULL) {
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for (i = 0; i < argc; i++)
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free(argv[i]);
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free(argv);
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}
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return r;
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}
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/*
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* Reassemble an argument vector into a string, quoting and escaping as
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* necessary. Caller must free returned string.
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*/
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static char *
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assemble_argv(int argc, char **argv)
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{
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int i, j, ws, r;
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char c, *ret;
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struct sshbuf *buf, *arg;
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if ((buf = sshbuf_new()) == NULL || (arg = sshbuf_new()) == NULL)
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fatal("%s: sshbuf_new failed", __func__);
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for (i = 0; i < argc; i++) {
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ws = 0;
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sshbuf_reset(arg);
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for (j = 0; argv[i][j] != '\0'; j++) {
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r = 0;
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c = argv[i][j];
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switch (c) {
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case ' ':
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case '\t':
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ws = 1;
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r = sshbuf_put_u8(arg, c);
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break;
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case '\\':
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case '\'':
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case '"':
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if ((r = sshbuf_put_u8(arg, '\\')) != 0)
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break;
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/* FALLTHROUGH */
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default:
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r = sshbuf_put_u8(arg, c);
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break;
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}
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if (r != 0)
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fatal("%s: sshbuf_put_u8: %s",
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__func__, ssh_err(r));
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}
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if ((i != 0 && (r = sshbuf_put_u8(buf, ' ')) != 0) ||
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(ws != 0 && (r = sshbuf_put_u8(buf, '"')) != 0) ||
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(r = sshbuf_putb(buf, arg)) != 0 ||
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(ws != 0 && (r = sshbuf_put_u8(buf, '"')) != 0))
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fatal("%s: buffer error: %s", __func__, ssh_err(r));
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}
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if ((ret = malloc(sshbuf_len(buf) + 1)) == NULL)
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fatal("%s: malloc failed", __func__);
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memcpy(ret, sshbuf_ptr(buf), sshbuf_len(buf));
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ret[sshbuf_len(buf)] = '\0';
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sshbuf_free(buf);
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sshbuf_free(arg);
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return ret;
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}
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/*
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* Runs command in a subprocess. Returns pid on success and a FILE* to the
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* subprocess' stdout or 0 on failure.
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* NB. "command" is only used for logging.
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*/
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static pid_t
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subprocess(const char *tag, struct passwd *pw, const char *command,
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int ac, char **av, FILE **child)
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{
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FILE *f;
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struct stat st;
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int devnull, p[2], i;
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pid_t pid;
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char *cp, errmsg[512];
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u_int envsize;
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char **child_env;
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*child = NULL;
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debug3("%s: %s command \"%s\" running as %s", __func__,
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tag, command, pw->pw_name);
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/* Verify the path exists and is safe-ish to execute */
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if (*av[0] != '/') {
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error("%s path is not absolute", tag);
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return 0;
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}
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temporarily_use_uid(pw);
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if (stat(av[0], &st) < 0) {
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error("Could not stat %s \"%s\": %s", tag,
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av[0], strerror(errno));
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restore_uid();
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return 0;
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}
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if (auth_secure_path(av[0], &st, NULL, 0,
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errmsg, sizeof(errmsg)) != 0) {
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error("Unsafe %s \"%s\": %s", tag, av[0], errmsg);
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restore_uid();
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return 0;
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}
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/*
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* Run the command; stderr is left in place, stdout is the
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* authorized_keys output.
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*/
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if (pipe(p) != 0) {
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error("%s: pipe: %s", tag, strerror(errno));
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restore_uid();
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return 0;
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}
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/*
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* Don't want to call this in the child, where it can fatal() and
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* run cleanup_exit() code.
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*/
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restore_uid();
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switch ((pid = fork())) {
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case -1: /* error */
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error("%s: fork: %s", tag, strerror(errno));
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close(p[0]);
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close(p[1]);
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return 0;
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case 0: /* child */
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/* Prepare a minimal environment for the child. */
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envsize = 5;
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child_env = xcalloc(sizeof(*child_env), envsize);
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child_set_env(&child_env, &envsize, "PATH", _PATH_STDPATH);
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child_set_env(&child_env, &envsize, "USER", pw->pw_name);
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child_set_env(&child_env, &envsize, "LOGNAME", pw->pw_name);
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child_set_env(&child_env, &envsize, "HOME", pw->pw_dir);
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if ((cp = getenv("LANG")) != NULL)
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child_set_env(&child_env, &envsize, "LANG", cp);
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for (i = 0; i < NSIG; i++)
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signal(i, SIG_DFL);
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if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1) {
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error("%s: open %s: %s", tag, _PATH_DEVNULL,
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strerror(errno));
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_exit(1);
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}
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/* Keep stderr around a while longer to catch errors */
|
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if (dup2(devnull, STDIN_FILENO) == -1 ||
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dup2(p[1], STDOUT_FILENO) == -1) {
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error("%s: dup2: %s", tag, strerror(errno));
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_exit(1);
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}
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closefrom(STDERR_FILENO + 1);
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|
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/* Don't use permanently_set_uid() here to avoid fatal() */
|
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if (setresgid(pw->pw_gid, pw->pw_gid, pw->pw_gid) != 0) {
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error("%s: setresgid %u: %s", tag, (u_int)pw->pw_gid,
|
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strerror(errno));
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_exit(1);
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}
|
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if (setresuid(pw->pw_uid, pw->pw_uid, pw->pw_uid) != 0) {
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error("%s: setresuid %u: %s", tag, (u_int)pw->pw_uid,
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strerror(errno));
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_exit(1);
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}
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/* stdin is pointed to /dev/null at this point */
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if (dup2(STDIN_FILENO, STDERR_FILENO) == -1) {
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error("%s: dup2: %s", tag, strerror(errno));
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_exit(1);
|
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}
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|
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execve(av[0], av, child_env);
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error("%s exec \"%s\": %s", tag, command, strerror(errno));
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_exit(127);
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default: /* parent */
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break;
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}
|
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|
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close(p[1]);
|
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if ((f = fdopen(p[0], "r")) == NULL) {
|
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error("%s: fdopen: %s", tag, strerror(errno));
|
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close(p[0]);
|
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/* Don't leave zombie child */
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kill(pid, SIGTERM);
|
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while (waitpid(pid, NULL, 0) == -1 && errno == EINTR)
|
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;
|
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return 0;
|
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}
|
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/* Success */
|
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debug3("%s: %s pid %ld", __func__, tag, (long)pid);
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*child = f;
|
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return pid;
|
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}
|
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|
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/* Returns 0 if pid exited cleanly, non-zero otherwise */
|
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static int
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exited_cleanly(pid_t pid, const char *tag, const char *cmd)
|
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{
|
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int status;
|
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|
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while (waitpid(pid, &status, 0) == -1) {
|
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if (errno != EINTR) {
|
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error("%s: waitpid: %s", tag, strerror(errno));
|
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return -1;
|
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}
|
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}
|
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if (WIFSIGNALED(status)) {
|
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error("%s %s exited on signal %d", tag, cmd, WTERMSIG(status));
|
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return -1;
|
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} else if (WEXITSTATUS(status) != 0) {
|
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error("%s %s failed, status %d", tag, cmd, WEXITSTATUS(status));
|
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return -1;
|
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}
|
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return 0;
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}
|
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|
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static int
|
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match_principals_option(const char *principal_list, struct sshkey_cert *cert)
|
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{
|
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@ -656,7 +373,7 @@ match_principals_command(struct passwd *user_pw, const struct sshkey *key)
|
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}
|
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|
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/* Turn the command into an argument vector */
|
||||
if (split_argv(options.authorized_principals_command, &ac, &av) != 0) {
|
||||
if (argv_split(options.authorized_principals_command, &ac, &av) != 0) {
|
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error("AuthorizedPrincipalsCommand \"%s\" contains "
|
||||
"invalid quotes", command);
|
||||
goto out;
|
||||
@ -705,10 +422,11 @@ match_principals_command(struct passwd *user_pw, const struct sshkey *key)
|
||||
av[i] = tmp;
|
||||
}
|
||||
/* Prepare a printable command for logs, etc. */
|
||||
command = assemble_argv(ac, av);
|
||||
command = argv_assemble(ac, av);
|
||||
|
||||
if ((pid = subprocess("AuthorizedPrincipalsCommand", pw, command,
|
||||
ac, av, &f)) == 0)
|
||||
ac, av, &f,
|
||||
SSH_SUBPROCESS_STDOUT_CAPTURE|SSH_SUBPROCESS_STDERR_DISCARD)) == 0)
|
||||
goto out;
|
||||
|
||||
uid_swapped = 1;
|
||||
@ -996,7 +714,7 @@ user_key_command_allowed2(struct passwd *user_pw, struct sshkey *key)
|
||||
}
|
||||
|
||||
/* Turn the command into an argument vector */
|
||||
if (split_argv(options.authorized_keys_command, &ac, &av) != 0) {
|
||||
if (argv_split(options.authorized_keys_command, &ac, &av) != 0) {
|
||||
error("AuthorizedKeysCommand \"%s\" contains invalid quotes",
|
||||
command);
|
||||
goto out;
|
||||
@ -1020,7 +738,7 @@ user_key_command_allowed2(struct passwd *user_pw, struct sshkey *key)
|
||||
av[i] = tmp;
|
||||
}
|
||||
/* Prepare a printable command for logs, etc. */
|
||||
command = assemble_argv(ac, av);
|
||||
command = argv_assemble(ac, av);
|
||||
|
||||
/*
|
||||
* If AuthorizedKeysCommand was run without arguments
|
||||
@ -1037,7 +755,8 @@ user_key_command_allowed2(struct passwd *user_pw, struct sshkey *key)
|
||||
}
|
||||
|
||||
if ((pid = subprocess("AuthorizedKeysCommand", pw, command,
|
||||
ac, av, &f)) == 0)
|
||||
ac, av, &f,
|
||||
SSH_SUBPROCESS_STDOUT_CAPTURE|SSH_SUBPROCESS_STDERR_DISCARD)) == 0)
|
||||
goto out;
|
||||
|
||||
uid_swapped = 1;
|
||||
|
||||
468
misc.c
468
misc.c
@ -1,4 +1,4 @@
|
||||
/* $OpenBSD: misc.c,v 1.111 2017/07/23 23:37:02 djm Exp $ */
|
||||
/* $OpenBSD: misc.c,v 1.112 2017/08/18 05:36:45 djm Exp $ */
|
||||
/*
|
||||
* Copyright (c) 2000 Markus Friedl. All rights reserved.
|
||||
* Copyright (c) 2005,2006 Damien Miller. All rights reserved.
|
||||
@ -29,10 +29,16 @@
|
||||
#include <sys/types.h>
|
||||
#include <sys/ioctl.h>
|
||||
#include <sys/socket.h>
|
||||
#include <sys/stat.h>
|
||||
#include <sys/time.h>
|
||||
#include <sys/wait.h>
|
||||
#include <sys/un.h>
|
||||
|
||||
#include <limits.h>
|
||||
#ifdef HAVE_LIBGEN_H
|
||||
# include <libgen.h>
|
||||
#endif
|
||||
#include <signal.h>
|
||||
#include <stdarg.h>
|
||||
#include <stdio.h>
|
||||
#include <stdlib.h>
|
||||
@ -61,6 +67,9 @@
|
||||
#include "misc.h"
|
||||
#include "log.h"
|
||||
#include "ssh.h"
|
||||
#include "sshbuf.h"
|
||||
#include "ssherr.h"
|
||||
#include "uidswap.h"
|
||||
|
||||
/* remove newline at end of string */
|
||||
char *
|
||||
@ -1275,3 +1284,460 @@ daemonized(void)
|
||||
debug3("already daemonized");
|
||||
return 1;
|
||||
}
|
||||
|
||||
|
||||
/*
|
||||
* Splits 's' into an argument vector. Handles quoted string and basic
|
||||
* escape characters (\\, \", \'). Caller must free the argument vector
|
||||
* and its members.
|
||||
*/
|
||||
int
|
||||
argv_split(const char *s, int *argcp, char ***argvp)
|
||||
{
|
||||
int r = SSH_ERR_INTERNAL_ERROR;
|
||||
int argc = 0, quote, i, j;
|
||||
char *arg, **argv = xcalloc(1, sizeof(*argv));
|
||||
|
||||
*argvp = NULL;
|
||||
*argcp = 0;
|
||||
|
||||
for (i = 0; s[i] != '\0'; i++) {
|
||||
/* Skip leading whitespace */
|
||||
if (s[i] == ' ' || s[i] == '\t')
|
||||
continue;
|
||||
|
||||
/* Start of a token */
|
||||
quote = 0;
|
||||
if (s[i] == '\\' &&
|
||||
(s[i + 1] == '\'' || s[i + 1] == '\"' || s[i + 1] == '\\'))
|
||||
i++;
|
||||
else if (s[i] == '\'' || s[i] == '"')
|
||||
quote = s[i++];
|
||||
|
||||
argv = xreallocarray(argv, (argc + 2), sizeof(*argv));
|
||||
arg = argv[argc++] = xcalloc(1, strlen(s + i) + 1);
|
||||
argv[argc] = NULL;
|
||||
|
||||
/* Copy the token in, removing escapes */
|
||||
for (j = 0; s[i] != '\0'; i++) {
|
||||
if (s[i] == '\\') {
|
||||
if (s[i + 1] == '\'' ||
|
||||
s[i + 1] == '\"' ||
|
||||
s[i + 1] == '\\') {
|
||||
i++; /* Skip '\' */
|
||||
arg[j++] = s[i];
|
||||
} else {
|
||||
/* Unrecognised escape */
|
||||
arg[j++] = s[i];
|
||||
}
|
||||
} else if (quote == 0 && (s[i] == ' ' || s[i] == '\t'))
|
||||
break; /* done */
|
||||
else if (quote != 0 && s[i] == quote)
|
||||
break; /* done */
|
||||
else
|
||||
arg[j++] = s[i];
|
||||
}
|
||||
if (s[i] == '\0') {
|
||||
if (quote != 0) {
|
||||
/* Ran out of string looking for close quote */
|
||||
r = SSH_ERR_INVALID_FORMAT;
|
||||
goto out;
|
||||
}
|
||||
break;
|
||||
}
|
||||
}
|
||||
/* Success */
|
||||
*argcp = argc;
|
||||
*argvp = argv;
|
||||
argc = 0;
|
||||
argv = NULL;
|
||||
r = 0;
|
||||
out:
|
||||
if (argc != 0 && argv != NULL) {
|
||||
for (i = 0; i < argc; i++)
|
||||
free(argv[i]);
|
||||
free(argv);
|
||||
}
|
||||
return r;
|
||||
}
|
||||
|
||||
/*
|
||||
* Reassemble an argument vector into a string, quoting and escaping as
|
||||
* necessary. Caller must free returned string.
|
||||
*/
|
||||
char *
|
||||
argv_assemble(int argc, char **argv)
|
||||
{
|
||||
int i, j, ws, r;
|
||||
char c, *ret;
|
||||
struct sshbuf *buf, *arg;
|
||||
|
||||
if ((buf = sshbuf_new()) == NULL || (arg = sshbuf_new()) == NULL)
|
||||
fatal("%s: sshbuf_new failed", __func__);
|
||||
|
||||
for (i = 0; i < argc; i++) {
|
||||
ws = 0;
|
||||
sshbuf_reset(arg);
|
||||
for (j = 0; argv[i][j] != '\0'; j++) {
|
||||
r = 0;
|
||||
c = argv[i][j];
|
||||
switch (c) {
|
||||
case ' ':
|
||||
case '\t':
|
||||
ws = 1;
|
||||
r = sshbuf_put_u8(arg, c);
|
||||
break;
|
||||
case '\\':
|
||||
case '\'':
|
||||
case '"':
|
||||
if ((r = sshbuf_put_u8(arg, '\\')) != 0)
|
||||
break;
|
||||
/* FALLTHROUGH */
|
||||
default:
|
||||
r = sshbuf_put_u8(arg, c);
|
||||
break;
|
||||
}
|
||||
if (r != 0)
|
||||
fatal("%s: sshbuf_put_u8: %s",
|
||||
__func__, ssh_err(r));
|
||||
}
|
||||
if ((i != 0 && (r = sshbuf_put_u8(buf, ' ')) != 0) ||
|
||||
(ws != 0 && (r = sshbuf_put_u8(buf, '"')) != 0) ||
|
||||
(r = sshbuf_putb(buf, arg)) != 0 ||
|
||||
(ws != 0 && (r = sshbuf_put_u8(buf, '"')) != 0))
|
||||
fatal("%s: buffer error: %s", __func__, ssh_err(r));
|
||||
}
|
||||
if ((ret = malloc(sshbuf_len(buf) + 1)) == NULL)
|
||||
fatal("%s: malloc failed", __func__);
|
||||
memcpy(ret, sshbuf_ptr(buf), sshbuf_len(buf));
|
||||
ret[sshbuf_len(buf)] = '\0';
|
||||
sshbuf_free(buf);
|
||||
sshbuf_free(arg);
|
||||
return ret;
|
||||
}
|
||||
|
||||
/*
|
||||
* Runs command in a subprocess wuth 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("%s: %s command \"%s\" running as %s (flags 0x%x)", __func__,
|
||||
tag, command, pw->pw_name, flags);
|
||||
|
||||
/* Check consistency */
|
||||
if ((flags & SSH_SUBPROCESS_STDOUT_DISCARD) != 0 &&
|
||||
(flags & SSH_SUBPROCESS_STDOUT_CAPTURE) != 0) {
|
||||
error("%s: inconsistent flags", __func__);
|
||||
return 0;
|
||||
}
|
||||
if (((flags & SSH_SUBPROCESS_STDOUT_CAPTURE) == 0) != (child == NULL)) {
|
||||
error("%s: inconsistent flags/output", __func__);
|
||||
return 0;
|
||||
}
|
||||
|
||||
/*
|
||||
* If executing an explicit binary, then verify the it exists
|
||||
* and appears safe-ish to execute
|
||||
*/
|
||||
if (*av[0] != '/') {
|
||||
error("%s path is not absolute", tag);
|
||||
return 0;
|
||||
}
|
||||
temporarily_use_uid(pw);
|
||||
if (stat(av[0], &st) < 0) {
|
||||
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) != 0) {
|
||||
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++)
|
||||
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) != 0) {
|
||||
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) != 0) {
|
||||
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("%s: %s pid %ld", __func__, tag, (long)pid);
|
||||
if (child != NULL)
|
||||
*child = f;
|
||||
return pid;
|
||||
}
|
||||
|
||||
/* Returns 0 if pid exited cleanly, non-zero otherwise */
|
||||
int
|
||||
exited_cleanly(pid_t pid, const char *tag, const char *cmd)
|
||||
{
|
||||
int status;
|
||||
|
||||
while (waitpid(pid, &status, 0) == -1) {
|
||||
if (errno != EINTR) {
|
||||
error("%s: waitpid: %s", tag, strerror(errno));
|
||||
return -1;
|
||||
}
|
||||
}
|
||||
if (WIFSIGNALED(status)) {
|
||||
error("%s %s exited on signal %d", tag, cmd, WTERMSIG(status));
|
||||
return -1;
|
||||
} else if (WEXITSTATUS(status) != 0) {
|
||||
error("%s %s failed, status %d", tag, cmd, WEXITSTATUS(status));
|
||||
return -1;
|
||||
}
|
||||
return 0;
|
||||
}
|
||||
|
||||
/*
|
||||
* Check a given path for security. This is defined as all components
|
||||
* of the path to the file must be owned by either the owner of
|
||||
* of the file or root and no directories must be group or world writable.
|
||||
*
|
||||
* XXX Should any specific check be done for sym links ?
|
||||
*
|
||||
* Takes a file name, its stat information (preferably from fstat() to
|
||||
* avoid races), the uid of the expected owner, their home directory and an
|
||||
* error buffer plus max size as arguments.
|
||||
*
|
||||
* Returns 0 on success and -1 on failure
|
||||
*/
|
||||
int
|
||||
safe_path(const char *name, struct stat *stp, const char *pw_dir,
|
||||
uid_t uid, char *err, size_t errlen)
|
||||
{
|
||||
char buf[PATH_MAX], homedir[PATH_MAX];
|
||||
char *cp;
|
||||
int comparehome = 0;
|
||||
struct stat st;
|
||||
|
||||
if (realpath(name, buf) == NULL) {
|
||||
snprintf(err, errlen, "realpath %s failed: %s", name,
|
||||
strerror(errno));
|
||||
return -1;
|
||||
}
|
||||
if (pw_dir != NULL && realpath(pw_dir, homedir) != NULL)
|
||||
comparehome = 1;
|
||||
|
||||
if (!S_ISREG(stp->st_mode)) {
|
||||
snprintf(err, errlen, "%s is not a regular file", buf);
|
||||
return -1;
|
||||
}
|
||||
if ((!platform_sys_dir_uid(stp->st_uid) && stp->st_uid != uid) ||
|
||||
(stp->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));
|
||||
|
||||
if (stat(buf, &st) < 0 ||
|
||||
(!platform_sys_dir_uid(st.st_uid) && st.st_uid != uid) ||
|
||||
(st.st_mode & 022) != 0) {
|
||||
snprintf(err, errlen,
|
||||
"bad ownership or modes for directory %s", buf);
|
||||
return -1;
|
||||
}
|
||||
|
||||
/* If are past the homedir then we can stop */
|
||||
if (comparehome && strcmp(homedir, buf) == 0)
|
||||
break;
|
||||
|
||||
/*
|
||||
* 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;
|
||||
}
|
||||
|
||||
/*
|
||||
* Version of safe_path() that accepts an open file descriptor to
|
||||
* avoid races.
|
||||
*
|
||||
* Returns 0 on success and -1 on failure
|
||||
*/
|
||||
int
|
||||
safe_path_fd(int fd, const char *file, struct passwd *pw,
|
||||
char *err, size_t errlen)
|
||||
{
|
||||
struct stat st;
|
||||
|
||||
/* check the open file to avoid races */
|
||||
if (fstat(fd, &st) < 0) {
|
||||
snprintf(err, errlen, "cannot stat file %s: %s",
|
||||
file, strerror(errno));
|
||||
return -1;
|
||||
}
|
||||
return safe_path(file, &st, pw->pw_dir, pw->pw_uid, err, errlen);
|
||||
}
|
||||
|
||||
/*
|
||||
* Sets the value of the given variable in the environment. If the variable
|
||||
* already exists, its value is overridden.
|
||||
*/
|
||||
void
|
||||
child_set_env(char ***envp, u_int *envsizep, const char *name,
|
||||
const char *value)
|
||||
{
|
||||
char **env;
|
||||
u_int envsize;
|
||||
u_int i, namelen;
|
||||
|
||||
if (strchr(name, '=') != NULL) {
|
||||
error("Invalid environment variable \"%.100s\"", name);
|
||||
return;
|
||||
}
|
||||
|
||||
/*
|
||||
* If we're passed an uninitialized list, allocate a single null
|
||||
* entry before continuing.
|
||||
*/
|
||||
if (*envp == NULL && *envsizep == 0) {
|
||||
*envp = xmalloc(sizeof(char *));
|
||||
*envp[0] = NULL;
|
||||
*envsizep = 1;
|
||||
}
|
||||
|
||||
/*
|
||||
* Find the slot where the value should be stored. If the variable
|
||||
* already exists, we reuse the slot; otherwise we append a new slot
|
||||
* at the end of the array, expanding if necessary.
|
||||
*/
|
||||
env = *envp;
|
||||
namelen = strlen(name);
|
||||
for (i = 0; env[i]; i++)
|
||||
if (strncmp(env[i], name, namelen) == 0 && env[i][namelen] == '=')
|
||||
break;
|
||||
if (env[i]) {
|
||||
/* Reuse the slot. */
|
||||
free(env[i]);
|
||||
} else {
|
||||
/* New variable. Expand if necessary. */
|
||||
envsize = *envsizep;
|
||||
if (i >= envsize - 1) {
|
||||
if (envsize >= 1000)
|
||||
fatal("child_set_env: too many env vars");
|
||||
envsize += 50;
|
||||
env = (*envp) = xreallocarray(env, envsize, sizeof(char *));
|
||||
*envsizep = envsize;
|
||||
}
|
||||
/* Need to set the NULL pointer at end of array beyond the new slot. */
|
||||
env[i + 1] = NULL;
|
||||
}
|
||||
|
||||
/* Allocate space and format the variable in the appropriate slot. */
|
||||
env[i] = xmalloc(strlen(name) + 1 + strlen(value) + 1);
|
||||
snprintf(env[i], strlen(name) + 1 + strlen(value) + 1, "%s=%s", name, value);
|
||||
}
|
||||
|
||||
|
||||
22
misc.h
22
misc.h
@ -1,4 +1,4 @@
|
||||
/* $OpenBSD: misc.h,v 1.61 2016/11/30 00:28:31 dtucker Exp $ */
|
||||
/* $OpenBSD: misc.h,v 1.62 2017/08/18 05:36:45 djm Exp $ */
|
||||
|
||||
/*
|
||||
* Author: Tatu Ylonen <ylo@cs.hut.fi>
|
||||
@ -16,6 +16,7 @@
|
||||
#define _MISC_H
|
||||
|
||||
#include <sys/time.h>
|
||||
#include <sys/types.h>
|
||||
|
||||
/* Data structure for representing a forwarding request. */
|
||||
struct Forward {
|
||||
@ -132,6 +133,25 @@ int parse_ipqos(const char *);
|
||||
const char *iptos2str(int);
|
||||
void mktemp_proto(char *, size_t);
|
||||
|
||||
void child_set_env(char ***envp, u_int *envsizep, const char *name,
|
||||
const char *value);
|
||||
|
||||
int argv_split(const char *, int *, char ***);
|
||||
char *argv_assemble(int, char **argv);
|
||||
int exited_cleanly(pid_t, const char *, const char *);
|
||||
|
||||
#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);
|
||||
|
||||
struct stat;
|
||||
int safe_path(const char *, struct stat *, const char *, uid_t,
|
||||
char *, size_t);
|
||||
int safe_path_fd(int, const char *, struct passwd *,
|
||||
char *err, size_t errlen);
|
||||
|
||||
/* readpass.c */
|
||||
|
||||
#define RP_ECHO 0x0001
|
||||
|
||||
61
session.c
61
session.c
@ -1,4 +1,4 @@
|
||||
/* $OpenBSD: session.c,v 1.290 2017/06/24 06:34:38 djm Exp $ */
|
||||
/* $OpenBSD: session.c,v 1.291 2017/08/18 05:36:45 djm Exp $ */
|
||||
/*
|
||||
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
|
||||
* All rights reserved
|
||||
@ -824,65 +824,6 @@ check_quietlogin(Session *s, const char *command)
|
||||
return 0;
|
||||
}
|
||||
|
||||
/*
|
||||
* Sets the value of the given variable in the environment. If the variable
|
||||
* already exists, its value is overridden.
|
||||
*/
|
||||
void
|
||||
child_set_env(char ***envp, u_int *envsizep, const char *name,
|
||||
const char *value)
|
||||
{
|
||||
char **env;
|
||||
u_int envsize;
|
||||
u_int i, namelen;
|
||||
|
||||
if (strchr(name, '=') != NULL) {
|
||||
error("Invalid environment variable \"%.100s\"", name);
|
||||
return;
|
||||
}
|
||||
|
||||
/*
|
||||
* If we're passed an uninitialized list, allocate a single null
|
||||
* entry before continuing.
|
||||
*/
|
||||
if (*envp == NULL && *envsizep == 0) {
|
||||
*envp = xmalloc(sizeof(char *));
|
||||
*envp[0] = NULL;
|
||||
*envsizep = 1;
|
||||
}
|
||||
|
||||
/*
|
||||
* Find the slot where the value should be stored. If the variable
|
||||
* already exists, we reuse the slot; otherwise we append a new slot
|
||||
* at the end of the array, expanding if necessary.
|
||||
*/
|
||||
env = *envp;
|
||||
namelen = strlen(name);
|
||||
for (i = 0; env[i]; i++)
|
||||
if (strncmp(env[i], name, namelen) == 0 && env[i][namelen] == '=')
|
||||
break;
|
||||
if (env[i]) {
|
||||
/* Reuse the slot. */
|
||||
free(env[i]);
|
||||
} else {
|
||||
/* New variable. Expand if necessary. */
|
||||
envsize = *envsizep;
|
||||
if (i >= envsize - 1) {
|
||||
if (envsize >= 1000)
|
||||
fatal("child_set_env: too many env vars");
|
||||
envsize += 50;
|
||||
env = (*envp) = xreallocarray(env, envsize, sizeof(char *));
|
||||
*envsizep = envsize;
|
||||
}
|
||||
/* Need to set the NULL pointer at end of array beyond the new slot. */
|
||||
env[i + 1] = NULL;
|
||||
}
|
||||
|
||||
/* Allocate space and format the variable in the appropriate slot. */
|
||||
env[i] = xmalloc(strlen(name) + 1 + strlen(value) + 1);
|
||||
snprintf(env[i], strlen(name) + 1 + strlen(value) + 1, "%s=%s", name, value);
|
||||
}
|
||||
|
||||
/*
|
||||
* Reads environment variables from the given file and adds/overrides them
|
||||
* into the environment. If the file does not exist, this does nothing.
|
||||
|
||||
@ -1,4 +1,4 @@
|
||||
/* $OpenBSD: session.h,v 1.33 2016/08/13 17:47:41 markus Exp $ */
|
||||
/* $OpenBSD: session.h,v 1.34 2017/08/18 05:36:45 djm Exp $ */
|
||||
|
||||
/*
|
||||
* Copyright (c) 2000, 2001 Markus Friedl. All rights reserved.
|
||||
@ -77,8 +77,6 @@ Session *session_new(void);
|
||||
Session *session_by_tty(char *);
|
||||
void session_close(Session *);
|
||||
void do_setusercontext(struct passwd *);
|
||||
void child_set_env(char ***envp, u_int *envsizep, const char *name,
|
||||
const char *value);
|
||||
|
||||
const char *session_get_remote_name_or_ip(struct ssh *, u_int, int);
|
||||
|
||||
|
||||
Loading…
Reference in New Issue
Block a user