3 files changed, 88 insertions, 32 deletions

diff --git a/ChangeLog b/ChangeLog
index 31f205f6a..647d71def 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -5,6 +5,11 @@
  - (dtucker) [roaming_client.c] Wrap inttypes.h in an ifdef.
  - (dtucker) [loginrec.c] Use the SUSv3 specified name for the user name
    when using utmpx.  Patch from Ed Schouten.
+ - (dtucker) OpenBSD CVS Sync
+   - djm@cvs.openbsd.org 2010/01/09 00:20:26
+     [sftp-server.c sftp-server.8]
+     add a 'read-only' mode to sftp-server(8) that disables open in write mode
+     and all other fs-modifying protocol methods. bz#430 ok dtucker@
 
 20091208
  - (dtucker) OpenBSD CVS Sync
diff --git a/sftp-server.8 b/sftp-server.8
index ee73c345b..84036922c 100644
--- a/sftp-server.8
+++ b/sftp-server.8
@@ -1,4 +1,4 @@
-.\" $OpenBSD: sftp-server.8,v 1.17 2009/08/31 21:01:29 djm Exp $
+.\" $OpenBSD: sftp-server.8,v 1.18 2010/01/09 00:20:26 djm Exp $
 .\"
 .\" Copyright (c) 2000 Markus Friedl.  All rights reserved.
 .\"
@@ -22,7 +22,7 @@
 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.Dd $Mdocdate: August 31 2009 $
+.Dd $Mdocdate: January 9 2010 $
 .Dt SFTP-SERVER 8
 .Os
 .Sh NAME
@@ -30,7 +30,7 @@
 .Nd SFTP server subsystem
 .Sh SYNOPSIS
 .Nm sftp-server
-.Op Fl eh
+.Op Fl ehR
 .Op Fl f Ar log_facility
 .Op Fl l Ar log_level
 .Op Fl u Ar umask
@@ -81,6 +81,12 @@ performs on behalf of the client.
 DEBUG and DEBUG1 are equivalent.
 DEBUG2 and DEBUG3 each specify higher levels of debugging output.
 The default is ERROR.
+.It Fl R
+Places this instance of
+.Nm
+into a read-only mode.
+Attempts to open files for writing, as well as other operations that change
+the state of the filesystem will be denied.
 .It Fl u Ar umask
 Sets an explicit
 .Xr umask 2
diff --git a/sftp-server.c b/sftp-server.c
index cf4e273f8..ab9391cfd 100644
--- a/sftp-server.c
+++ b/sftp-server.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sftp-server.c,v 1.89 2010/01/04 02:25:15 djm Exp $ */
+/* $OpenBSD: sftp-server.c,v 1.90 2010/01/09 00:20:26 djm Exp $ */
 /*
  * Copyright (c) 2000-2004 Markus Friedl.  All rights reserved.
  *
@@ -70,6 +70,9 @@ Buffer oqueue;
 /* Version of client */
 int version;
 
+/* Disable writes */
+int readonly;
+
 /* portable attributes, etc. */
 
 typedef struct Stat Stat;
@@ -553,16 +556,21 @@ process_open(void)
         mode = (a->flags & SSH2_FILEXFER_ATTR_PERMISSIONS) ? a->perm : 0666;
         logit("open \"%s\" flags %s mode 0%o",
             name, string_from_portable(pflags), mode);
-        fd = open(name, flags, mode);
-        if (fd < 0) {
-                status = errno_to_portable(errno);
-        } else {
-                handle = handle_new(HANDLE_FILE, name, fd, NULL);
-                if (handle < 0) {
-                        close(fd);
+        if (readonly &&
+            ((flags & O_ACCMODE) == O_WRONLY || (flags & O_ACCMODE) == O_RDWR))
+                status = SSH2_FX_PERMISSION_DENIED;
+        else {
+                fd = open(name, flags, mode);
+                if (fd < 0) {
+                        status = errno_to_portable(errno);
                 } else {
-                        send_handle(id, handle);
-                        status = SSH2_FX_OK;
+                        handle = handle_new(HANDLE_FILE, name, fd, NULL);
+                        if (handle < 0) {
+                                close(fd);
+                        } else {
+                                send_handle(id, handle);
+                                status = SSH2_FX_OK;
+                        }
                 }
         }
         if (status != SSH2_FX_OK)
@@ -632,7 +640,7 @@ process_write(void)
         u_int32_t id;
         u_int64_t off;
         u_int len;
-        int handle, fd, ret, status = SSH2_FX_FAILURE;
+        int handle, fd, ret, status;
         char *data;
 
         id = get_int();
@@ -643,7 +651,12 @@ process_write(void)
         debug("request %u: write \"%s\" (handle %d) off %llu len %d",
             id, handle_to_name(handle), handle, (unsigned long long)off, len);
         fd = handle_to_fd(handle);
-        if (fd >= 0) {
+        
+        if (fd < 0)
+                status = SSH2_FX_FAILURE;
+        else if (readonly)
+                status = SSH2_FX_PERMISSION_DENIED;
+        else {
                 if (lseek(fd, off, SEEK_SET) < 0) {
                         status = errno_to_portable(errno);
                         error("process_write: seek failed");
@@ -658,6 +671,7 @@ process_write(void)
                                 handle_update_write(handle, ret);
                         } else {
                                 debug2("nothing at all written");
+                                status = SSH2_FX_FAILURE;
                         }
                 }
         }
@@ -754,6 +768,10 @@ process_setstat(void)
         name = get_string(NULL);
         a = get_attrib();
         debug("request %u: setstat name \"%s\"", id, name);
+        if (readonly) {
+                status = SSH2_FX_PERMISSION_DENIED;
+                a->flags = 0;
+        }
         if (a->flags & SSH2_FILEXFER_ATTR_SIZE) {
                 logit("set \"%s\" size %llu",
                     name, (unsigned long long)a->size);
@@ -802,9 +820,11 @@ process_fsetstat(void)
         a = get_attrib();
         debug("request %u: fsetstat handle %d", id, handle);
         fd = handle_to_fd(handle);
-        if (fd < 0) {
+        if (fd < 0)
                 status = SSH2_FX_FAILURE;
-        } else {
+        else if (readonly)
+                status = SSH2_FX_PERMISSION_DENIED;
+        else {
                 char *name = handle_to_name(handle);
 
                 if (a->flags & SSH2_FILEXFER_ATTR_SIZE) {
@@ -952,8 +972,12 @@ process_remove(void)
         name = get_string(NULL);
         debug3("request %u: remove", id);
         logit("remove name \"%s\"", name);
-        ret = unlink(name);
-        status = (ret == -1) ? errno_to_portable(errno) : SSH2_FX_OK;
+        if (readonly)
+                status = SSH2_FX_PERMISSION_DENIED;
+        else {
+                ret = unlink(name);
+                status = (ret == -1) ? errno_to_portable(errno) : SSH2_FX_OK;
+        }
         send_status(id, status);
         xfree(name);
 }
@@ -973,8 +997,12 @@ process_mkdir(void)
             a->perm & 07777 : 0777;
         debug3("request %u: mkdir", id);
         logit("mkdir name \"%s\" mode 0%o", name, mode);
-        ret = mkdir(name, mode);
-        status = (ret == -1) ? errno_to_portable(errno) : SSH2_FX_OK;
+        if (readonly)
+                status = SSH2_FX_PERMISSION_DENIED;
+        else {
+                ret = mkdir(name, mode);
+                status = (ret == -1) ? errno_to_portable(errno) : SSH2_FX_OK;
+        }
         send_status(id, status);
         xfree(name);
 }
@@ -990,8 +1018,12 @@ process_rmdir(void)
         name = get_string(NULL);
         debug3("request %u: rmdir", id);
         logit("rmdir name \"%s\"", name);
-        ret = rmdir(name);
-        status = (ret == -1) ? errno_to_portable(errno) : SSH2_FX_OK;
+        if (readonly)
+                status = SSH2_FX_PERMISSION_DENIED;
+        else {
+                ret = rmdir(name);
+                status = (ret == -1) ? errno_to_portable(errno) : SSH2_FX_OK;
+        }
         send_status(id, status);
         xfree(name);
 }
@@ -1036,7 +1068,9 @@ process_rename(void)
         debug3("request %u: rename", id);
         logit("rename old \"%s\" new \"%s\"", oldpath, newpath);
         status = SSH2_FX_FAILURE;
-        if (lstat(oldpath, &sb) == -1)
+        if (readonly)
+                status = SSH2_FX_PERMISSION_DENIED;
+        else if (lstat(oldpath, &sb) == -1)
                 status = errno_to_portable(errno);
         else if (S_ISREG(sb.st_mode)) {
                 /* Race-free rename of regular files */
@@ -1120,8 +1154,12 @@ process_symlink(void)
         debug3("request %u: symlink", id);
         logit("symlink old \"%s\" new \"%s\"", oldpath, newpath);
         /* this will fail if 'newpath' exists */
-        ret = symlink(oldpath, newpath);
-        status = (ret == -1) ? errno_to_portable(errno) : SSH2_FX_OK;
+        if (readonly)
+                status = SSH2_FX_PERMISSION_DENIED;
+        else {
+                ret = symlink(oldpath, newpath);
+                status = (ret == -1) ? errno_to_portable(errno) : SSH2_FX_OK;
+        }
         send_status(id, status);
         xfree(oldpath);
         xfree(newpath);
@@ -1131,15 +1169,19 @@ static void
 process_extended_posix_rename(u_int32_t id)
 {
         char *oldpath, *newpath;
+        int ret, status;
 
         oldpath = get_string(NULL);
         newpath = get_string(NULL);
         debug3("request %u: posix-rename", id);
         logit("posix-rename old \"%s\" new \"%s\"", oldpath, newpath);
-        if (rename(oldpath, newpath) == -1)
-                send_status(id, errno_to_portable(errno));
-        else
-                send_status(id, SSH2_FX_OK);
+        if (readonly)
+                status = SSH2_FX_PERMISSION_DENIED;
+        else {
+                ret = rename(oldpath, newpath);
+                status = (ret == -1) ? errno_to_portable(errno) : SSH2_FX_OK;
+        }
+        send_status(id, status);
         xfree(oldpath);
         xfree(newpath);
 }
@@ -1322,7 +1364,7 @@ sftp_server_usage(void)
         extern char *__progname;
 
         fprintf(stderr,
-            "usage: %s [-eh] [-f log_facility] [-l log_level] [-u umask]\n",
+            "usage: %s [-ehR] [-f log_facility] [-l log_level] [-u umask]\n",
             __progname);
         exit(1);
 }
@@ -1344,8 +1386,11 @@ sftp_server_main(int argc, char **argv, struct passwd *user_pw)
         __progname = ssh_get_progname(argv[0]);
         log_init(__progname, log_level, log_facility, log_stderr);
 
-        while (!skipargs && (ch = getopt(argc, argv, "f:l:u:che")) != -1) {
+        while (!skipargs && (ch = getopt(argc, argv, "f:l:u:cehR")) != -1) {
                 switch (ch) {
+                case 'R':
+                        readonly = 1;
+                        break;
                 case 'c':
                         /*
                          * Ignore all arguments if we are invoked as a