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- djm@cvs.openbsd.org 2008/02/08 23:24:07
[servconf.c servconf.h session.c sftp-server.c sftp.h sshd_config]
[sshd_config.5]
add sshd_config ChrootDirectory option to chroot(2) users to a directory
and tweak internal sftp server to work with it (no special files in
chroot required). ok markus@
This commit is contained in:
Damien Miller
parent
dfc24258a7
commit
d8cb1f184f
@ -1,4 +1,4 @@
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# $Id: Makefile.in,v 1.285 2007/06/11 04:01:42 djm Exp $
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# $Id: Makefile.in,v 1.286 2008/02/10 11:40:12 djm Exp $
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# uncomment if you run a non bourne compatable shell. Ie. csh
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#SHELL = @SH@
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@ -156,8 +156,8 @@ ssh-keysign$(EXEEXT): $(LIBCOMPAT) libssh.a ssh-keysign.o
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ssh-keyscan$(EXEEXT): $(LIBCOMPAT) libssh.a ssh-keyscan.o
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$(LD) -o $@ ssh-keyscan.o $(LDFLAGS) -lssh -lopenbsd-compat -lssh $(LIBS)
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sftp-server$(EXEEXT): $(LIBCOMPAT) libssh.a sftp.o sftp-common.o sftp-server.o
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$(LD) -o $@ sftp-server.o sftp-common.o $(LDFLAGS) -lssh -lopenbsd-compat $(LIBS)
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sftp-server$(EXEEXT): $(LIBCOMPAT) libssh.a sftp.o sftp-common.o sftp-server.o sftp-server-main.o
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$(LD) -o $@ sftp-server.o sftp-common.o sftp-server-main.o $(LDFLAGS) -lssh -lopenbsd-compat $(LIBS)
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sftp$(EXEEXT): $(LIBCOMPAT) libssh.a sftp.o sftp-client.o sftp-common.o sftp-glob.o progressmeter.o
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$(LD) -o $@ progressmeter.o sftp.o sftp-client.o sftp-common.o sftp-glob.o $(LDFLAGS) -lssh -lopenbsd-compat $(LIBS) $(LIBEDIT)
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12
servconf.c
12
servconf.c
@ -1,4 +1,4 @@
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/* $OpenBSD: servconf.c,v 1.175 2008/01/01 09:27:33 dtucker Exp $ */
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/* $OpenBSD: servconf.c,v 1.176 2008/02/08 23:24:08 djm Exp $ */
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/*
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* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
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* All rights reserved
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@ -122,6 +122,7 @@ initialize_server_options(ServerOptions *options)
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options->permit_tun = -1;
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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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}
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void
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@ -291,7 +292,7 @@ typedef enum {
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sHostbasedUsesNameFromPacketOnly, sClientAliveInterval,
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sClientAliveCountMax, sAuthorizedKeysFile, sAuthorizedKeysFile2,
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sGssAuthentication, sGssCleanupCreds, sAcceptEnv, sPermitTunnel,
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sMatch, sPermitOpen, sForceCommand,
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sMatch, sPermitOpen, sForceCommand, sChrootDirectory,
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sUsePrivilegeSeparation,
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sDeprecated, sUnsupported
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} ServerOpCodes;
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@ -403,6 +404,7 @@ static struct {
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{ "match", sMatch, SSHCFG_ALL },
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{ "permitopen", sPermitOpen, SSHCFG_ALL },
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{ "forcecommand", sForceCommand, SSHCFG_ALL },
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{ "chrootdirectory", sChrootDirectory, SSHCFG_ALL },
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{ NULL, sBadOption, 0 }
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};
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@ -1147,6 +1149,7 @@ parse_flag:
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case sBanner:
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charptr = &options->banner;
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goto parse_filename;
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/*
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* These options can contain %X options expanded at
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* connect time, so that you can specify paths like:
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@ -1255,6 +1258,10 @@ parse_flag:
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options->adm_forced_command = xstrdup(cp + len);
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return 0;
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case sChrootDirectory:
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charptr = &options->chroot_directory;
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goto parse_filename;
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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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@ -1363,6 +1370,7 @@ copy_set_server_options(ServerOptions *dst, ServerOptions *src, int preauth)
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if (preauth)
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return;
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M_CP_STROPT(adm_forced_command);
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M_CP_STROPT(chroot_directory);
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}
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#undef M_CP_INTOPT
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@ -1,4 +1,4 @@
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/* $OpenBSD: servconf.h,v 1.80 2007/02/19 10:45:58 dtucker Exp $ */
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/* $OpenBSD: servconf.h,v 1.81 2008/02/08 23:24:08 djm Exp $ */
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/*
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* Author: Tatu Ylonen <ylo@cs.hut.fi>
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@ -141,6 +141,8 @@ typedef struct {
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int permit_tun;
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int num_permitted_opens;
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char *chroot_directory;
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} ServerOptions;
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void initialize_server_options(ServerOptions *);
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106
session.c
106
session.c
@ -1,4 +1,4 @@
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/* $OpenBSD: session.c,v 1.225 2008/02/04 21:53:00 markus Exp $ */
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/* $OpenBSD: session.c,v 1.226 2008/02/08 23:24:07 djm Exp $ */
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/*
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* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
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* All rights reserved
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@ -84,6 +84,7 @@
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#include "sshlogin.h"
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#include "serverloop.h"
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#include "canohost.h"
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#include "misc.h"
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#include "session.h"
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#include "kex.h"
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#include "monitor_wrap.h"
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@ -93,6 +94,9 @@
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#include <kafs.h>
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#endif
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/* Magic name for internal sftp-server */
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#define INTERNAL_SFTP_NAME "internal-sftp"
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/* func */
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Session *session_new(void);
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@ -130,7 +134,7 @@ extern Buffer loginmsg;
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const char *original_command = NULL;
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/* data */
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#define MAX_SESSIONS 10
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#define MAX_SESSIONS 20
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Session sessions[MAX_SESSIONS];
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#define SUBSYSTEM_NONE 0
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@ -688,13 +692,17 @@ do_exec(Session *s, const char *command)
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if (options.adm_forced_command) {
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original_command = command;
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command = options.adm_forced_command;
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if (s->is_subsystem)
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if (strcmp(INTERNAL_SFTP_NAME, command) == 0)
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s->is_subsystem = SUBSYSTEM_INT_SFTP;
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else if (s->is_subsystem)
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s->is_subsystem = SUBSYSTEM_EXT;
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debug("Forced command (config) '%.900s'", command);
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} else if (forced_command) {
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original_command = command;
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command = forced_command;
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if (s->is_subsystem)
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if (strcmp(INTERNAL_SFTP_NAME, command) == 0)
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s->is_subsystem = SUBSYSTEM_INT_SFTP;
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else if (s->is_subsystem)
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s->is_subsystem = SUBSYSTEM_EXT;
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debug("Forced command (key option) '%.900s'", command);
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}
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@ -710,7 +718,6 @@ do_exec(Session *s, const char *command)
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PRIVSEP(audit_run_command(shell));
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}
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#endif
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if (s->ttyfd != -1)
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do_exec_pty(s, command);
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else
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@ -1293,6 +1300,61 @@ do_nologin(struct passwd *pw)
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}
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}
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/*
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* Chroot into a directory after checking it for safety: all path components
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* must be root-owned directories with strict permissions.
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*/
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static void
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safely_chroot(const char *path, uid_t uid)
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{
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const char *cp;
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char component[MAXPATHLEN];
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struct stat st;
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if (*path != '/')
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fatal("chroot path does not begin at root");
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if (strlen(path) >= sizeof(component))
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fatal("chroot path too long");
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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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for (cp = path; cp != NULL;) {
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if ((cp = strchr(cp, '/')) == NULL)
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strlcpy(component, path, sizeof(component));
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else {
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cp++;
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memcpy(component, path, cp - path);
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component[cp - path] = '\0';
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}
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debug3("%s: checking '%s'", __func__, component);
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if (stat(component, &st) != 0)
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fatal("%s: stat(\"%s\"): %s", __func__,
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component, strerror(errno));
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if (st.st_uid != 0 || (st.st_mode & 022) != 0)
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fatal("bad ownership or modes for chroot "
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"directory %s\"%s\"",
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cp == NULL ? "" : "component ", component);
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if (!S_ISDIR(st.st_mode))
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fatal("chroot path %s\"%s\" is not a directory",
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cp == NULL ? "" : "component ", component);
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}
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if (chdir(path) == -1)
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fatal("Unable to chdir to chroot path \"%s\": "
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"%s", path, strerror(errno));
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if (chroot(path) == -1)
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fatal("chroot(\"%s\"): %s", path, strerror(errno));
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if (chdir("/") == -1)
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fatal("%s: chdir(/) after chroot: %s",
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__func__, strerror(errno));
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verbose("Changed root directory to \"%s\"", path);
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}
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/* Set login name, uid, gid, and groups. */
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void
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do_setusercontext(struct passwd *pw)
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@ -1324,7 +1386,7 @@ do_setusercontext(struct passwd *pw)
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}
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# endif /* USE_PAM */
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if (setusercontext(lc, pw, pw->pw_uid,
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(LOGIN_SETALL & ~LOGIN_SETPATH)) < 0) {
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(LOGIN_SETALL & ~(LOGIN_SETPATH|LOGIN_SETUSER))) < 0) {
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perror("unable to set user context");
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exit(1);
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}
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@ -1347,13 +1409,13 @@ do_setusercontext(struct passwd *pw)
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exit(1);
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}
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endgrent();
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#ifdef GSSAPI
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# ifdef GSSAPI
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if (options.gss_authentication) {
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temporarily_use_uid(pw);
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ssh_gssapi_storecreds();
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restore_uid();
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}
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#endif
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# endif
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# ifdef USE_PAM
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/*
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* PAM credentials may take the form of supplementary groups.
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@ -1367,15 +1429,33 @@ do_setusercontext(struct passwd *pw)
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# endif /* USE_PAM */
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# if defined(WITH_IRIX_PROJECT) || defined(WITH_IRIX_JOBS) || defined(WITH_IRIX_ARRAY)
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irix_setusercontext(pw);
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# endif /* defined(WITH_IRIX_PROJECT) || defined(WITH_IRIX_JOBS) || defined(WITH_IRIX_ARRAY) */
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# endif /* defined(WITH_IRIX_PROJECT) || defined(WITH_IRIX_JOBS) || defined(WITH_IRIX_ARRAY) */
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# ifdef _AIX
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aix_usrinfo(pw);
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# endif /* _AIX */
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#ifdef USE_LIBIAF
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# ifdef USE_LIBIAF
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if (set_id(pw->pw_name) != 0) {
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exit(1);
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}
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#endif /* USE_LIBIAF */
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# endif /* USE_LIBIAF */
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#endif
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if (options.chroot_directory != NULL &&
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strcasecmp(options.chroot_directory, "none") != 0) {
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char *chroot_path;
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chroot_path = percent_expand(options.chroot_directory,
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"h", pw->pw_dir, "u", pw->pw_name, (char *)NULL);
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safely_chroot(chroot_path, pw->pw_uid);
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free(chroot_path);
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}
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#ifdef HAVE_LOGIN_CAP
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if (setusercontext(lc, pw, pw->pw_uid, LOGIN_SETUSER) < 0) {
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perror("unable to set user context (setuser)");
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exit(1);
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}
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#else
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/* Permanently switch to the desired uid. */
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permanently_set_uid(pw);
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#endif
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@ -1625,7 +1705,7 @@ do_child(Session *s, const char *command)
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argv[i] = NULL;
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optind = optreset = 1;
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__progname = argv[0];
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exit(sftp_server_main(i, argv));
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exit(sftp_server_main(i, argv, s->pw));
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}
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if (options.use_login) {
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@ -1900,7 +1980,7 @@ session_subsystem_req(Session *s)
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if (strcmp(subsys, options.subsystem_name[i]) == 0) {
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prog = options.subsystem_command[i];
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cmd = options.subsystem_args[i];
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if (!strcmp("internal-sftp", prog)) {
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if (!strcmp(INTERNAL_SFTP_NAME, prog)) {
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s->is_subsystem = SUBSYSTEM_INT_SFTP;
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} else if (stat(prog, &st) < 0) {
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error("subsystem: cannot stat %s: %s", prog,
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50
sftp-server-main.c
Normal file
50
sftp-server-main.c
Normal file
@ -0,0 +1,50 @@
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/* $OpenBSD: */
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/*
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* Copyright (c) 2008 Markus Friedl. All rights reserved.
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#include "includes.h"
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#include <sys/types.h>
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#include <pwd.h>
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#include <stdarg.h>
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#include <stdio.h>
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#include <unistd.h>
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#include "log.h"
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#include "sftp.h"
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#include "misc.h"
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void
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cleanup_exit(int i)
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{
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sftp_server_cleanup_exit(i);
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}
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int
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main(int argc, char **argv)
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{
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struct passwd *user_pw;
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/* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
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sanitise_stdfd();
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if ((user_pw = getpwuid(getuid())) == NULL) {
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fprintf(stderr, "No user found for uid %lu", (u_long)getuid());
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return 1;
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}
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return (sftp_server_main(argc, argv, user_pw));
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}
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@ -1,4 +1,4 @@
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/* $OpenBSD: sftp-server.c,v 1.76 2008/02/04 21:53:00 markus Exp $ */
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/* $OpenBSD: sftp-server.c,v 1.77 2008/02/08 23:24:07 djm Exp $ */
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/*
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* Copyright (c) 2000-2004 Markus Friedl. All rights reserved.
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*
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@ -1219,7 +1219,7 @@ sftp_server_usage(void)
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}
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int
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sftp_server_main(int argc, char **argv)
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sftp_server_main(int argc, char **argv, struct passwd *user_pw)
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{
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fd_set *rset, *wset;
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int in, out, max, ch, skipargs = 0, log_stderr = 0;
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@ -1277,11 +1277,7 @@ sftp_server_main(int argc, char **argv)
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} else
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client_addr = xstrdup("UNKNOWN");
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if ((pw = getpwuid(getuid())) == NULL) {
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error("No user found for uid %lu", (u_long)getuid());
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sftp_server_cleanup_exit(255);
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}
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pw = pwcopy(pw);
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pw = pwcopy(user_pw);
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logit("session opened for local user %s from [%s]",
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pw->pw_name, client_addr);
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6
sftp.h
6
sftp.h
@ -1,4 +1,4 @@
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/* $OpenBSD: sftp.h,v 1.6 2008/02/04 21:53:00 markus Exp $ */
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/* $OpenBSD: sftp.h,v 1.7 2008/02/08 23:24:07 djm Exp $ */
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/*
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* Copyright (c) 2001 Markus Friedl. All rights reserved.
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@ -91,5 +91,7 @@
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#define SSH2_FX_OP_UNSUPPORTED 8
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#define SSH2_FX_MAX 8
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int sftp_server_main(int, char **);
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struct passwd;
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int sftp_server_main(int, char **, struct passwd *);
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void sftp_server_cleanup_exit(int) __dead;
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@ -1,4 +1,4 @@
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# $OpenBSD: sshd_config,v 1.76 2007/08/23 03:22:16 djm Exp $
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# $OpenBSD: sshd_config,v 1.77 2008/02/08 23:24:07 djm Exp $
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# This is the sshd server system-wide configuration file. See
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# sshd_config(5) for more information.
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@ -102,6 +102,7 @@ Protocol 2
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#PidFile /var/run/sshd.pid
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#MaxStartups 10
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#PermitTunnel no
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#ChrootDirectory none
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# no default banner path
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#Banner none
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@ -34,8 +34,8 @@
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.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
|
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.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
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.\"
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.\" $OpenBSD: sshd_config.5,v 1.79 2008/01/01 09:27:33 dtucker Exp $
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.Dd $Mdocdate: January 1 2008 $
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.\" $OpenBSD: sshd_config.5,v 1.80 2008/02/08 23:24:07 djm Exp $
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.Dd $Mdocdate: February 8 2008 $
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.Dt SSHD_CONFIG 5
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.Os
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.Sh NAME
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@ -173,6 +173,45 @@ All authentication styles from
|
||||
are supported.
|
||||
The default is
|
||||
.Dq yes .
|
||||
.It Cm ChrootDirectory
|
||||
Specifies a path to
|
||||
.Xr chroot 2
|
||||
to after authentication.
|
||||
This path, and all its components, must be root-owned directories that are
|
||||
not writable by any other user or group.
|
||||
.Pp
|
||||
The path may contain the following tokens that are expanded at runtime once
|
||||
the connecting user has been authenticated: %% is replaced by a literal '%',
|
||||
%h is replaced by the home directory of the user being authenticated, and
|
||||
%u is replaced by the username of that user.
|
||||
.Pp
|
||||
The
|
||||
.Cm ChrootDirectory
|
||||
must contain the necessary files and directories to support the
|
||||
users' session.
|
||||
For an interactive session this requires at least a shell, typically
|
||||
.Xr sh 1 ,
|
||||
and basic
|
||||
.Pa /dev
|
||||
nodes such as
|
||||
.Xr null 4 ,
|
||||
.Xr zero 4 ,
|
||||
.Xr stdin 4 ,
|
||||
.Xr stdout 4 ,
|
||||
.Xr stderr 4 ,
|
||||
.Xr arandom 4
|
||||
and
|
||||
.Xr tty 4
|
||||
devices.
|
||||
For file transfer sessions using
|
||||
.Dq sftp ,
|
||||
no additional configuration of the environment is necessary if the
|
||||
in-process sftp server is used (see
|
||||
.Cm Subsystem
|
||||
for details.
|
||||
.Pp
|
||||
The default is not to
|
||||
.Xr chroot 2 .
|
||||
.It Cm Ciphers
|
||||
Specifies the ciphers allowed for protocol version 2.
|
||||
Multiple ciphers must be comma-separated.
|
||||
@ -740,11 +779,22 @@ The default is
|
||||
Configures an external subsystem (e.g. file transfer daemon).
|
||||
Arguments should be a subsystem name and a command (with optional arguments)
|
||||
to execute upon subsystem request.
|
||||
.Pp
|
||||
The command
|
||||
.Xr sftp-server 8
|
||||
implements the
|
||||
.Dq sftp
|
||||
file transfer subsystem.
|
||||
.Pp
|
||||
Alternately the name
|
||||
.Dq internal-sftp
|
||||
implements an in-process
|
||||
.Dq sftp
|
||||
server.
|
||||
This may simplify configurations using
|
||||
.Cm ChrootDirectory
|
||||
to force a different filesystem root on clients.
|
||||
.Pp
|
||||
By default no subsystems are defined.
|
||||
Note that this option applies to protocol version 2 only.
|
||||
.It Cm SyslogFacility
|
||||
|
||||
Loading…
Reference in New Issue
Block a user