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authorM. Mohan Kumar <mohan@in.ibm.com>2011-12-14 13:58:47 +0530
committerAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>2012-01-04 21:23:53 +0530
commita2d8f1beb11004e76aec5cd05ecb62f2b1037598 (patch)
tree42d414f6ff7b7983b927b2a46f8aac910e2c241f
parentf67e3ffd34ff8380a3e6d5fca0f6df440478c2ed (diff)
hw/9pfs: man page for proxy helper
Signed-off-by: M. Mohan Kumar <mohan@in.ibm.com> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
-rw-r--r--Makefile12
-rw-r--r--fsdev/virtfs-proxy-helper.texi59
2 files changed, 70 insertions, 1 deletions
diff --git a/Makefile b/Makefile
index c665b7243..9ce8768ce 100644
--- a/Makefile
+++ b/Makefile
@@ -38,6 +38,7 @@ LIBS+=-lz $(LIBS_TOOLS)
ifdef BUILD_DOCS
DOCS=qemu-doc.html qemu-tech.html qemu.1 qemu-img.1 qemu-nbd.8 QMP/qmp-commands.txt
+DOCS+=fsdev/virtfs-proxy-helper.1
else
DOCS=
endif
@@ -289,7 +290,10 @@ ifdef CONFIG_POSIX
$(INSTALL_DIR) "$(DESTDIR)$(mandir)/man8"
$(INSTALL_DATA) qemu-nbd.8 "$(DESTDIR)$(mandir)/man8"
endif
-
+ifdef CONFIG_VIRTFS
+ $(INSTALL_DIR) "$(DESTDIR)$(mandir)/man1"
+ $(INSTALL_DATA) fsdev/virtfs-proxy-helper.1 "$(DESTDIR)$(mandir)/man1"
+endif
install-sysconfig:
$(INSTALL_DIR) "$(DESTDIR)$(sysconfdir)/qemu"
$(INSTALL_DATA) $(SRC_PATH)/sysconfigs/target/target-x86_64.conf "$(DESTDIR)$(sysconfdir)/qemu"
@@ -373,6 +377,12 @@ qemu-img.1: qemu-img.texi qemu-img-cmds.texi
pod2man --section=1 --center=" " --release=" " qemu-img.pod > $@, \
" GEN $@")
+fsdev/virtfs-proxy-helper.1: fsdev/virtfs-proxy-helper.texi
+ $(call quiet-command, \
+ perl -Ww -- $(SRC_PATH)/scripts/texi2pod.pl $< fsdev/virtfs-proxy-helper.pod && \
+ pod2man --section=1 --center=" " --release=" " fsdev/virtfs-proxy-helper.pod > $@, \
+ " GEN $@")
+
qemu-nbd.8: qemu-nbd.texi
$(call quiet-command, \
perl -Ww -- $(SRC_PATH)/scripts/texi2pod.pl $< qemu-nbd.pod && \
diff --git a/fsdev/virtfs-proxy-helper.texi b/fsdev/virtfs-proxy-helper.texi
new file mode 100644
index 000000000..3816382bb
--- /dev/null
+++ b/fsdev/virtfs-proxy-helper.texi
@@ -0,0 +1,59 @@
+@example
+@c man begin SYNOPSIS
+usage: virtfs-proxy-helper options
+@c man end
+@end example
+
+@c man begin DESCRIPTION
+@table @description
+Pass-through security model in QEMU 9p server needs root privilege to do
+few file operations (like chown, chmod to any mode/uid:gid). There are two
+issues in pass-through security model
+
+1) TOCTTOU vulnerability: Following symbolic links in the server could
+provide access to files beyond 9p export path.
+
+2) Running QEMU with root privilege could be a security issue.
+
+To overcome above issues, following approach is used: A new filesytem
+type 'proxy' is introduced. Proxy FS uses chroot + socket combination
+for securing the vulnerability known with following symbolic links.
+Intention of adding a new filesystem type is to allow qemu to run
+in non-root mode, but doing privileged operations using socket IO.
+
+Proxy helper(a stand alone binary part of qemu) is invoked with
+root privileges. Proxy helper chroots into 9p export path and creates
+a socket pair or a named socket based on the command line parameter.
+Qemu and proxy helper communicate using this socket. QEMU proxy fs
+driver sends filesystem request to proxy helper and receives the
+response from it.
+
+Proxy helper is designed so that it can drop the root privilege with
+retaining capbilities needed for doing filesystem operations only.
+
+@end table
+@c man end
+
+@c man begin OPTIONS
+The following options are supported:
+@table @option
+@item -h
+@findex -h
+Display help and exit
+@item -p|--path path
+Path to export for proxy filesystem driver
+@item -f|--fd socket-id
+Use given file descriptor as socket descriptor for communicating with
+qemu proxy fs drier. Usually a helper like libvirt will create
+socketpair and pass one of the fds as parameter to -f|--fd
+@item -n|--nodaemon
+Run as a normal program. By default program will run in daemon mode
+@end table
+@c man end
+
+@setfilename virtfs-proxy-helper
+@settitle QEMU 9p virtfs proxy filesystem helper
+
+@c man begin AUTHOR
+M. Mohan Kumar
+@c man end