--- chrootenv.h +++ chrootenv.h @@ -0,0 +1,32 @@ +/* $OpenBSD: session.h,v 1.30 2008/05/08 12:21:16 djm Exp $ */ + +/* + * Copyright (c) 2000, 2001 Markus Friedl. All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + */ +#ifndef CHROOTENV_H +#define CHROOTENV_H + +extern int chroot_no_tree; + +#endif + --- session.c +++ session.c @@ -119,6 +119,8 @@ void do_child(Session *, const char *); void do_motd(void); int check_quietlogin(Session *, const char *); +int chroot_no_tree = 0; + static void do_authenticated1(Authctxt *); static void do_authenticated2(Authctxt *); @@ -802,6 +804,11 @@ do_exec(Session *s, const char *command) debug("Forced command (key option) '%.900s'", command); } + if ((s->is_subsystem != SUBSYSTEM_INT_SFTP) && chroot_no_tree) { + logit("You aren't welcomed, go away!"); + exit (1); + } + #ifdef SSH_AUDIT_EVENTS if (command != NULL) PRIVSEP(audit_run_command(command)); @@ -1399,6 +1406,63 @@ do_nologin(struct passwd *pw) } /* + * Test if filesystem is mounted nosuid and nodev + */ + +static void +test_nosuid (char * path, dev_t fs) +{ + FILE *f; + struct stat st; + char buf[4096], *s, *on, *mountpoint, *opt; + int nodev, nosuid; + + if (!(f = popen ("/bin/mount", "r"))) + fatal ("%s: popen(\"/bin/mount\", \"r\"): %s", + __func__, strerror (errno)); + for (;;) { + s = fgets (buf, sizeof (buf), f); + if (ferror (f)) + fatal ("%s: read from popen: %s", __func__, + strerror (errno)); + if (!s) { + pclose (f); + fatal ("cannot found filesystem with the chroot directory"); + } + (void) strtok (buf, " "); + on = strtok (NULL, " "); + if (strcmp (on, "on")) { + pclose (f); + fatal ("bad format of mount output"); + } + mountpoint = strtok (NULL, " "); + if (memcmp (path, mountpoint, strlen (mountpoint))) + continue; + if (stat(mountpoint, &st) != 0) { + pclose (f); + fatal("%s: stat(\"%s\"): %s", __func__, + mountpoint, strerror(errno)); + } + if (fs != st.st_dev) + continue; + nodev = nosuid = 0; + for (opt = strtok (NULL, "("); opt; opt = strtok (NULL, " ,)")) { + if (!strcmp (opt, "nodev")) + nodev = 1; + else if (!strcmp (opt, "nosuid")) + nosuid = 1; + else if (!strcmp (opt, "noexec")) + nosuid = 1; + if (nodev && nosuid) { + pclose (f); + return; + } + } + fatal ("chroot into directory without nodev or nosuid"); + } +} + +/* * Chroot into a directory after checking it for safety: all path components * must be root-owned directories with strict permissions. */ @@ -1408,6 +1472,7 @@ safely_chroot(const char *path, uid_t ui const char *cp; char component[MAXPATHLEN]; struct stat st; + int last; if (*path != '/') fatal("chroot path does not begin at root"); @@ -1419,7 +1484,7 @@ safely_chroot(const char *path, uid_t ui * root-owned directory with strict permissions. */ for (cp = path; cp != NULL;) { - if ((cp = strchr(cp, '/')) == NULL) + if (((last = ((cp = strchr(cp, '/')) == NULL)))) strlcpy(component, path, sizeof(component)); else { cp++; @@ -1432,14 +1497,20 @@ safely_chroot(const char *path, uid_t ui if (stat(component, &st) != 0) fatal("%s: stat(\"%s\"): %s", __func__, component, strerror(errno)); - if (st.st_uid != 0 || (st.st_mode & 022) != 0) + if ((st.st_uid != 0 || (st.st_mode & 022) != 0) && !(last && st.st_uid == uid)) fatal("bad ownership or modes for chroot " "directory %s\"%s\"", cp == NULL ? "" : "component ", component); if (!S_ISDIR(st.st_mode)) fatal("chroot path %s\"%s\" is not a directory", cp == NULL ? "" : "component ", component); + } + setenv ("TZ", "/etc/localtime", 0); + tzset (); + if (st.st_uid) { + test_nosuid (path, st.st_dev); + ++chroot_no_tree; } if (chdir(path) == -1) @@ -1451,6 +1522,10 @@ safely_chroot(const char *path, uid_t ui if (chdir("/") == -1) fatal("%s: chdir(/) after chroot: %s", __func__, strerror(errno)); + + if (access ("/etc/localtime", R_OK) < 0) + ++chroot_no_tree; + verbose("Changed root directory to \"%s\"", path); } --- sftp.c +++ sftp.c @@ -94,6 +94,8 @@ int remote_glob(struct sftp_conn *, cons extern char *__progname; +int chroot_no_tree = 0; + /* Separators for interactive commands */ #define WHITESPACE " \t\r\n" --- sftp-common.c +++ sftp-common.c @@ -40,6 +40,7 @@ #include "xmalloc.h" #include "buffer.h" #include "log.h" +#include "chrootenv.h" #include "sftp.h" #include "sftp-common.h" @@ -194,13 +195,13 @@ ls_file(const char *name, const struct s char buf[1024], mode[11+1], tbuf[12+1], ubuf[11+1], gbuf[11+1]; strmode(st->st_mode, mode); - if (!remote && (pw = getpwuid(st->st_uid)) != NULL) { + if (!remote && !chroot_no_tree && (pw = getpwuid(st->st_uid)) != NULL) { user = pw->pw_name; } else { snprintf(ubuf, sizeof ubuf, "%u", (u_int)st->st_uid); user = ubuf; } - if (!remote && (gr = getgrgid(st->st_gid)) != NULL) { + if (!remote && !chroot_no_tree && (gr = getgrgid(st->st_gid)) != NULL) { group = gr->gr_name; } else { snprintf(gbuf, sizeof gbuf, "%u", (u_int)st->st_gid); --- sftp-server-main.c +++ sftp-server-main.c @@ -22,11 +22,14 @@ #include #include #include +#include #include "log.h" #include "sftp.h" #include "misc.h" +int chroot_no_tree = 0; + void cleanup_exit(int i) { --- sshd_config.0 +++ sshd_config.0 @@ -112,6 +112,14 @@ DESCRIPTION essary if the in-process sftp server is used (see Subsystem for details). + In the special case when only sftp is used, not ssh nor scp, it + is possible to use ChrootDirectory %h or ChrootDirectory + /some/path/%u. The file system containing this directory must be + mounted with options nodev and either nosuid or noexec. The owner + of the directory should be the user. The ownership of the other + components of the path must fulfill the usual conditions. No adi- + tional files are required to be present in the directory. + The default is not to chroot(2). Ciphers --- sshd_config.5 +++ sshd_config.5 @@ -219,6 +219,17 @@ in-process sftp server is used (see .Cm Subsystem for details). .Pp +In the special case when only sftp is used, not ssh nor scp, +it is possible to use +.Cm ChrootDirectory +%h or +.Cm ChrootDirectory +/some/path/%u. The file system containing this directory must be +mounted with options nodev and either nosuid or noexec. The owner of the +directory should be the user. The ownership of the other components of the path +must fulfill the usual conditions. No aditional files are required to be present +in the directory. +.Pp The default is not to .Xr chroot 2 . .It Cm Ciphers