As recent CVE-2023-2861 (fixed by f6b0de53fb) once again showed, the 9p
'proxy' fs driver is in bad shape. Using the 'proxy' backend was already
discouraged for safety reasons before and we recommended to use the
'local' backend (preferably in conjunction with its 'mapped' security
model) instead, but now it is time to officially deprecate the 'proxy'
backend.
Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Message-Id: <E1qDkmw-0007M1-8f@lizzy.crudebyte.com>
We use the user_ss[] array to hold the user emulation sources,
and the softmmu_ss[] array to hold the system emulation ones.
Hold the latter in the 'system_ss[]' array for parity with user
emulation.
Mechanical change doing:
$ sed -i -e s/softmmu_ss/system_ss/g $(git grep -l softmmu_ss)
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230613133347.82210-10-philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
The 9p protocol does not specifically define how server shall behave when
client tries to open a special file, however from security POV it does
make sense for 9p server to prohibit opening any special file on host side
in general. A sane Linux 9p client for instance would never attempt to
open a special file on host side, it would always handle those exclusively
on its guest side. A malicious client however could potentially escape
from the exported 9p tree by creating and opening a device file on host
side.
With QEMU this could only be exploited in the following unsafe setups:
- Running QEMU binary as root AND 9p 'local' fs driver AND 'passthrough'
security model.
or
- Using 9p 'proxy' fs driver (which is running its helper daemon as
root).
These setups were already discouraged for safety reasons before,
however for obvious reasons we are now tightening behaviour on this.
Fixes: CVE-2023-2861
Reported-by: Yanwu Shen <ywsPlz@gmail.com>
Reported-by: Jietao Xiao <shawtao1125@gmail.com>
Reported-by: Jinku Li <jkli@xidian.edu.cn>
Reported-by: Wenbo Shen <shenwenbo@zju.edu.cn>
Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Michael Tokarev <mjt@tls.msk.ru>
Message-Id: <E1q6w7r-0000Q0-NM@lizzy.crudebyte.com>
One less qemu-specific macro. It also helps to make some headers/units
only depend on glib, and thus moved in standalone projects eventually.
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Richard W.M. Jones <rjones@redhat.com>
To allow VirtFS on darwin, we need to check that pthread_fchdir_np is
available, which has only been available since macOS 10.12.
Additionally, virtfs_proxy_helper is disabled on Darwin. This patch
series does not currently provide an implementation of the proxy-helper,
but this functionality could be implemented later on.
Signed-off-by: Keno Fischer <keno@juliacomputing.com>
[Michael Roitzsch: - Rebase for NixOS]
Signed-off-by: Michael Roitzsch <reactorcontrol@icloud.com>
[Will Cohen: - Rebase to master]
Signed-off-by: Will Cohen <wwcohen@gmail.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
[Will Cohen: - Add check for pthread_fchdir_np to virtfs
- Add comments to patch commit
- Note that virtfs_proxy_helper does not work
on macOS
- Fully adjust meson virtfs error note to specify
macOS
- Rebase to master]
Signed-off-by: Will Cohen <wwcohen@gmail.com>
Message-Id: <20220227223522.91937-12-wwcohen@gmail.com>
Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
Acked-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
- Guard Linux only headers.
- Add qemu/statfs.h header to abstract over the which
headers are needed for struct statfs
- Define `ENOATTR` only if not only defined
(it's defined in system headers on Darwin).
Signed-off-by: Keno Fischer <keno@juliacomputing.com>
[Michael Roitzsch: - Rebase for NixOS]
Signed-off-by: Michael Roitzsch <reactorcontrol@icloud.com>
While it might at first appear that fsdev/virtfs-proxy-header.c would
need similar adjustment for darwin as file-op-9p here, a later patch in
this series disables virtfs-proxy-helper for non-Linux. Allowing
virtfs-proxy-helper on darwin could potentially be an additional
optimization later.
[Will Cohen: - Fix headers for Alpine
- Integrate statfs.h back into file-op-9p.h
- Remove superfluous header guards from file-opt-9p
- Add note about virtfs-proxy-helper being disabled
on non-Linux for this patch series]
Signed-off-by: Will Cohen <wwcohen@gmail.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Greg Kurz <groug@kaod.org>
Message-Id: <20220227223522.91937-2-wwcohen@gmail.com>
Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
Implements deep auto free of arrays while retaining common C-style
squared bracket access. Main purpose of this API is to get rid of
error prone individual array deallocation pathes in user code, i.e.
turning something like this:
void doSomething(size_t n) {
Foo *foos = malloc(n * sizeof(Foo));
for (...) {
foos[i].s = malloc(...);
if (...) {
goto out;
}
}
out:
if (...) {
for (...) {
/* deep deallocation */
free(foos[i].s);
}
/* array deallocation */
free(foos);
}
}
into something more simple and safer like:
void doSomething(size_t n) {
P9ARRAY_REF(Foo) foos = NULL;
P9ARRAY_NEW(Foo, foos, n);
for (...) {
foos[i].s = malloc(...);
if (...) {
return; /* array auto freed here */
}
}
/* array auto freed here */
}
Unlike GArray, P9Array does not require special macros, function
calls or struct member dereferencing to access the individual array
elements:
C-array = P9Array: vs. GArray:
for (...) { | for (...) {
... = arr[i].m; | ... = g_array_index(arr, Foo, i).m;
arr[i].m = ... ; | g_array_index(arr, Foo, i).m = ... ;
} | }
So existing C-style array code can be retained with only very little
changes; basically limited to replacing array allocation call and of
course removing individual array deallocation pathes.
In this initial version P9Array only supports the concept of unique
pointers, i.e. it does not support reference counting. The array (and
all dynamically allocated memory of individual array elements) is auto
freed once execution leaves the scope of the reference variable (unique
pointer) associated with the array.
Internally a flex array struct is used in combination with macros
spanned over a continuous memory space for both the array's meta data
(private) and the actual C-array user data (public):
struct P9Array##scalar_type {
size_t len; /* private, hidden from user code */
scalar_type first[]; /* public, directly exposed to user code */
};
Which has the advantage that the compiler automatically takes care
about correct padding, alignment and overall size for all scalar data
types on all systems and that the user space exposed pointer can
directly be translated back and forth between user space C-array
pointer and internal P9Array struct whenever needed, in a type-safe
manner.
This header file is released under MIT license, to allow this file
being used in other C-projects as well. The common QEMU license
GPL2+ might have construed a conflict for other projects.
Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
Message-Id: <a954ef47b5ac26085a16c5c2aec8695374e0424d.1633097129.git.qemu_oss@crudebyte.com>
have_virtfs_proxy_helper is used from docs/meson.build, and can be
not declared when including it before fsdev/meson.build. This fixes:
../docs/meson.build:54:2: ERROR: Unknown variable "have_virtfs_proxy_helper".
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20210120151539.1166252-1-philmd@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Previous patch introduced a performance warning being logged on host
side if client connected with an 'msize' <= 8192. Disable this
performance warning for the synth driver to prevent that warning from
being printed whenever the 9pfs (qtest) test cases are running.
Introduce a new export flag V9FS_NO_PERF_WARN for that purpose, which
might also be used to disable such warnings from the CLI in future.
We could have also prevented the warning by simply raising P9_MAX_SIZE
in virtio-9p-test.c to any value larger than 8192, however in the
context of test cases it makes sense running for edge cases, which
includes the lowest 'msize' value supported by the server which is
4096, hence we want to preserve an msize of 4096 for the test client.
Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Message-Id: <E1kEyDy-0006nN-5A@lizzy.crudebyte.com>
Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
The virtfs-proxy-helper documentation is currently in
fsdev/qemu-trace-stap.texi in Texinfo format, which we
present to the user as:
* a virtfs-proxy-helper manpage
* but not (unusually for QEMU) part of the HTML docs
Convert the documentation to rST format that lives in
the docs/ subdirectory, and present it to the user as:
* a virtfs-proxy-helper manpage
* part of the interop/ Sphinx manual
There are minor formatting changes to suit Sphinx, but no
content changes. In particular I've split the -u and -g
options into each having their own description text.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Acked-by: Greg Kurz <groug@kaod.org>
Message-id: 20200124162606.8787-9-peter.maydell@linaro.org
