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qemu: Add security fixes for CVE-2020-35517

Browse Source 
This series is based on
https://lists.gnu.org/archive/html/qemu-devel/2021-02/msg01787.html, and
was kindly brought up by David Gilbert.

Fixes: #1361

Signed-off-by: Fabiano Fidêncio <fidencio@redhat.com>
This commit is contained in:
Fabiano Fidêncio 2021-02-04 22:26:20 +01:00
parent 38b5a43267
commit b548114f59
12 changed files with 1440 additions and 0 deletions
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104
tools/packaging/qemu/patches/5.0.x/0004-virtiofsd-Add-o-allow_direct_io-no_allow_direct_io-o.patch Normal file
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@ -0,0 +1,104 @@
From f876aae825d77aec1a735ecf5b2bc821eba11913 Mon Sep 17 00:00:00 2001
From: Jiachen Zhang <zhangjiachen.jaycee@bytedance.com>
Date: Thu, 4 Feb 2021 22:22:03 +0100
Subject: [PATCH] virtiofsd: Add -o allow_direct_io|no_allow_direct_io options
Due to the commit 65da4539803373ec4eec97ffc49ee90083e56efd, the O_DIRECT
open flag of guest applications will be discarded by virtiofsd. While
this behavior makes it consistent with the virtio-9p scheme when guest
applications use direct I/O, we no longer have any chance to bypass the
host page cache.
Therefore, we add a flag 'allow_direct_io' to lo_data. If '-o
no_allow_direct_io' option is added, or none of '-o allow_direct_io' or
'-o no_allow_direct_io' is added, the 'allow_direct_io' will be set to
0, and virtiofsd discards O_DIRECT as before. If '-o allow_direct_io'
is added to the starting command-line, 'allow_direct_io' will be set to
1, so that the O_DIRECT flags will be retained and host page cache can
be bypassed.
Signed-off-by: Jiachen Zhang <zhangjiachen.jaycee@bytedance.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20200824105957.61265-1-zhangjiachen.jaycee@bytedance.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
tools/virtiofsd/passthrough_ll.c | 20 ++++++++++++++------
1 file changed, 14 insertions(+), 6 deletions(-)
diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
index f7b9c1d2..bec60352 100644
--- a/tools/virtiofsd/passthrough_ll.c
+++ b/tools/virtiofsd/passthrough_ll.c
@@ -151,6 +151,7 @@ struct lo_data {
int timeout_set;
int readdirplus_set;
int readdirplus_clear;
+ int allow_direct_io;
struct lo_inode root;
GHashTable *inodes; /* protected by lo->mutex */
struct lo_map ino_map; /* protected by lo->mutex */
@@ -179,6 +180,8 @@ static const struct fuse_opt lo_opts[] = {
{ "norace", offsetof(struct lo_data, norace), 1 },
{ "readdirplus", offsetof(struct lo_data, readdirplus_set), 1 },
{ "no_readdirplus", offsetof(struct lo_data, readdirplus_clear), 1 },
+ { "allow_direct_io", offsetof(struct lo_data, allow_direct_io), 1 },
+ { "no_allow_direct_io", offsetof(struct lo_data, allow_direct_io), 0 },
FUSE_OPT_END
};
static bool use_syslog = false;
@@ -1677,7 +1680,8 @@ static void lo_releasedir(fuse_req_t req, fuse_ino_t ino,
fuse_reply_err(req, 0);
}
-static void update_open_flags(int writeback, struct fuse_file_info *fi)
+static void update_open_flags(int writeback, int allow_direct_io,
+ struct fuse_file_info *fi)
{
/*
* With writeback cache, kernel may send read requests even
@@ -1702,10 +1706,13 @@ static void update_open_flags(int writeback, struct fuse_file_info *fi)
/*
* O_DIRECT in guest should not necessarily mean bypassing page
- * cache on host as well. If somebody needs that behavior, it
- * probably should be a configuration knob in daemon.
+ * cache on host as well. Therefore, we discard it by default
+ * ('-o no_allow_direct_io'). If somebody needs that behavior,
+ * the '-o allow_direct_io' option should be set.
*/
- fi->flags &= ~O_DIRECT;
+ if (!allow_direct_io) {
+ fi->flags &= ~O_DIRECT;
+ }
}
static void lo_create(fuse_req_t req, fuse_ino_t parent, const char *name,
@@ -1737,7 +1744,7 @@ static void lo_create(fuse_req_t req, fuse_ino_t parent, const char *name,
goto out;
}
- update_open_flags(lo->writeback, fi);
+ update_open_flags(lo->writeback, lo->allow_direct_io, fi);
fd = openat(parent_inode->fd, name, (fi->flags | O_CREAT) & ~O_NOFOLLOW,
mode);
@@ -1947,7 +1954,7 @@ static void lo_open(fuse_req_t req, fuse_ino_t ino, struct fuse_file_info *fi)
fuse_log(FUSE_LOG_DEBUG, "lo_open(ino=%" PRIu64 ", flags=%d)\n", ino,
fi->flags);
- update_open_flags(lo->writeback, fi);
+ update_open_flags(lo->writeback, lo->allow_direct_io, fi);
sprintf(buf, "%i", lo_fd(req, ino));
fd = openat(lo->proc_self_fd, buf, fi->flags & ~O_NOFOLLOW);
@@ -2852,6 +2859,7 @@ int main(int argc, char *argv[])
.debug = 0,
.writeback = 0,
.posix_lock = 1,
+ .allow_direct_io = 0,
.proc_self_fd = -1,
};
struct lo_map_elem *root_elem;
--
2.29.2

145
tools/packaging/qemu/patches/5.0.x/0005-virtiofsd-extract-lo_do_open-from-lo_open.patch Normal file
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@ -0,0 +1,145 @@
From 7979901047bdad744b1cfaedb1fa99dc4c5738b8 Mon Sep 17 00:00:00 2001
From: Stefan Hajnoczi <stefanha@redhat.com>
Date: Thu, 4 Feb 2021 20:16:42 +0100
Subject: [PATCH] virtiofsd: extract lo_do_open() from lo_open()
Both lo_open() and lo_create() have similar code to open a file. Extract
a common lo_do_open() function from lo_open() that will be used by
lo_create() in a later commit.
Since lo_do_open() does not otherwise need fuse_req_t req, convert
lo_add_fd_mapping() to use struct lo_data *lo instead.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20210204150208.367837-2-stefanha@redhat.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
tools/virtiofsd/passthrough_ll.c | 73 ++++++++++++++++++++------------
1 file changed, 46 insertions(+), 27 deletions(-)
diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
index bec60352..6eb6a754 100644
--- a/tools/virtiofsd/passthrough_ll.c
+++ b/tools/virtiofsd/passthrough_ll.c
@@ -442,17 +442,17 @@ static void lo_map_remove(struct lo_map *map, size_t key)
}
/* Assumes lo->mutex is held */
-static ssize_t lo_add_fd_mapping(fuse_req_t req, int fd)
+static ssize_t lo_add_fd_mapping(struct lo_data *lo, int fd)
{
struct lo_map_elem *elem;
- elem = lo_map_alloc_elem(&lo_data(req)->fd_map);
+ elem = lo_map_alloc_elem(&lo->fd_map);
if (!elem) {
return -1;
}
elem->fd = fd;
- return elem - lo_data(req)->fd_map.elems;
+ return elem - lo->fd_map.elems;
}
/* Assumes lo->mutex is held */
@@ -1715,6 +1715,38 @@ static void update_open_flags(int writeback, int allow_direct_io,
}
}
+static int lo_do_open(struct lo_data *lo, struct lo_inode *inode,
+ struct fuse_file_info *fi)
+{
+ char buf[64];
+ ssize_t fh;
+ int fd;
+
+ update_open_flags(lo->writeback, lo->allow_direct_io, fi);
+
+ sprintf(buf, "%i", inode->fd);
+ fd = openat(lo->proc_self_fd, buf, fi->flags & ~O_NOFOLLOW);
+ if (fd == -1) {
+ return errno;
+ }
+
+ pthread_mutex_lock(&lo->mutex);
+ fh = lo_add_fd_mapping(lo, fd);
+ pthread_mutex_unlock(&lo->mutex);
+ if (fh == -1) {
+ close(fd);
+ return ENOMEM;
+ }
+
+ fi->fh = fh;
+ if (lo->cache == CACHE_NONE) {
+ fi->direct_io = 1;
+ } else if (lo->cache == CACHE_ALWAYS) {
+ fi->keep_cache = 1;
+ }
+ return 0;
+}
+
static void lo_create(fuse_req_t req, fuse_ino_t parent, const char *name,
mode_t mode, struct fuse_file_info *fi)
{
@@ -1755,7 +1787,7 @@ static void lo_create(fuse_req_t req, fuse_ino_t parent, const char *name,
ssize_t fh;
pthread_mutex_lock(&lo->mutex);
- fh = lo_add_fd_mapping(req, fd);
+ fh = lo_add_fd_mapping(lo, fd);
pthread_mutex_unlock(&lo->mutex);
if (fh == -1) {
close(fd);
@@ -1946,38 +1978,25 @@ static void lo_fsyncdir(fuse_req_t req, fuse_ino_t ino, int datasync,
static void lo_open(fuse_req_t req, fuse_ino_t ino, struct fuse_file_info *fi)
{
- int fd;
- ssize_t fh;
- char buf[64];
struct lo_data *lo = lo_data(req);
+ struct lo_inode *inode = lo_inode(req, ino);
+ int err;
fuse_log(FUSE_LOG_DEBUG, "lo_open(ino=%" PRIu64 ", flags=%d)\n", ino,
fi->flags);
- update_open_flags(lo->writeback, lo->allow_direct_io, fi);
-
- sprintf(buf, "%i", lo_fd(req, ino));
- fd = openat(lo->proc_self_fd, buf, fi->flags & ~O_NOFOLLOW);
- if (fd == -1) {
- return (void)fuse_reply_err(req, errno);
- }
-
- pthread_mutex_lock(&lo->mutex);
- fh = lo_add_fd_mapping(req, fd);
- pthread_mutex_unlock(&lo->mutex);
- if (fh == -1) {
- close(fd);
- fuse_reply_err(req, ENOMEM);
+ if (!inode) {
+ fuse_reply_err(req, EBADF);
return;
}
- fi->fh = fh;
- if (lo->cache == CACHE_NONE) {
- fi->direct_io = 1;
- } else if (lo->cache == CACHE_ALWAYS) {
- fi->keep_cache = 1;
+ err = lo_do_open(lo, inode, fi);
+ lo_inode_put(lo, &inode);
+ if (err) {
+ fuse_reply_err(req, err);
+ } else {
+ fuse_reply_open(req, fi);
}
- fuse_reply_open(req, fi);
}
static void lo_release(fuse_req_t req, fuse_ino_t ino,
--
2.29.2

109
tools/packaging/qemu/patches/5.0.x/0006-virtiofsd-optionally-return-inode-pointer-from-lo_do.patch Normal file
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@ -0,0 +1,109 @@
From 6772514121ccfecc0824b8f2ec39377368c564a0 Mon Sep 17 00:00:00 2001
From: Stefan Hajnoczi <stefanha@redhat.com>
Date: Thu, 4 Feb 2021 15:02:07 +0000
Subject: [PATCH] virtiofsd: optionally return inode pointer from
lo_do_lookup()
lo_do_lookup() finds an existing inode or allocates a new one. It
increments nlookup so that the inode stays alive until the client
releases it.
Existing callers don't need the struct lo_inode so the function doesn't
return it. Extend the function to optionally return the inode. The next
commit will need it.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Message-Id: <20210204150208.367837-3-stefanha@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
tools/virtiofsd/passthrough_ll.c | 29 +++++++++++++++++++++--------
1 file changed, 21 insertions(+), 8 deletions(-)
diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
index 6eb6a754..422ea75f 100644
--- a/tools/virtiofsd/passthrough_ll.c
+++ b/tools/virtiofsd/passthrough_ll.c
@@ -881,11 +881,13 @@ static void posix_locks_value_destroy(gpointer data)
}
/*
- * Increments nlookup and caller must release refcount using
- * lo_inode_put(&parent).
+ * Increments nlookup on the inode on success. unref_inode_lolocked() must be
+ * called eventually to decrement nlookup again. If inodep is non-NULL, the
+ * inode pointer is stored and the caller must call lo_inode_put().
*/
static int lo_do_lookup(fuse_req_t req, fuse_ino_t parent, const char *name,
- struct fuse_entry_param *e)
+ struct fuse_entry_param *e,
+ struct lo_inode **inodep)
{
int newfd;
int res;
@@ -894,6 +896,10 @@ static int lo_do_lookup(fuse_req_t req, fuse_ino_t parent, const char *name,
struct lo_inode *inode = NULL;
struct lo_inode *dir = lo_inode(req, parent);
+ if (inodep) {
+ *inodep = NULL;
+ }
+
/*
* name_to_handle_at() and open_by_handle_at() can reach here with fuse
* mount point in guest, but we don't have its inode info in the
@@ -954,7 +960,14 @@ static int lo_do_lookup(fuse_req_t req, fuse_ino_t parent, const char *name,
pthread_mutex_unlock(&lo->mutex);
}
e->ino = inode->fuse_ino;
- lo_inode_put(lo, &inode);
+
+ /* Transfer ownership of inode pointer to caller or drop it */
+ if (inodep) {
+ *inodep = inode;
+ } else {
+ lo_inode_put(lo, &inode);
+ }
+
lo_inode_put(lo, &dir);
fuse_log(FUSE_LOG_DEBUG, " %lli/%s -> %lli\n", (unsigned long long)parent,
@@ -989,7 +1002,7 @@ static void lo_lookup(fuse_req_t req, fuse_ino_t parent, const char *name)
return;
}
- err = lo_do_lookup(req, parent, name, &e);
+ err = lo_do_lookup(req, parent, name, &e, NULL);
if (err) {
fuse_reply_err(req, err);
} else {
@@ -1097,7 +1110,7 @@ static void lo_mknod_symlink(fuse_req_t req, fuse_ino_t parent,
goto out;
}
- saverr = lo_do_lookup(req, parent, name, &e);
+ saverr = lo_do_lookup(req, parent, name, &e, NULL);
if (saverr) {
goto out;
}
@@ -1598,7 +1611,7 @@ static void lo_do_readdir(fuse_req_t req, fuse_ino_t ino, size_t size,
if (plus) {
if (!is_dot_or_dotdot(name)) {
- err = lo_do_lookup(req, ino, name, &e);
+ err = lo_do_lookup(req, ino, name, &e, NULL);
if (err) {
goto error;
}
@@ -1796,7 +1809,7 @@ static void lo_create(fuse_req_t req, fuse_ino_t parent, const char *name,
}
fi->fh = fh;
- err = lo_do_lookup(req, parent, name, &e);
+ err = lo_do_lookup(req, parent, name, &e, NULL);
}
if (lo->cache == CACHE_NONE) {
fi->direct_io = 1;
--
2.29.2

298
tools/packaging/qemu/patches/5.0.x/0007-virtiofsd-prevent-opening-of-special-files-CVE-2020-.patch Normal file
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@ -0,0 +1,298 @@
From 19f9b9c7fb8433830b661441c6646cda42223354 Mon Sep 17 00:00:00 2001
From: Stefan Hajnoczi <stefanha@redhat.com>
Date: Thu, 4 Feb 2021 20:20:00 +0100
Subject: [PATCH] virtiofsd: prevent opening of special files (CVE-2020-35517)
A well-behaved FUSE client does not attempt to open special files with
FUSE_OPEN because they are handled on the client side (e.g. device nodes
are handled by client-side device drivers).
The check to prevent virtiofsd from opening special files is missing in
a few cases, most notably FUSE_OPEN. A malicious client can cause
virtiofsd to open a device node, potentially allowing the guest to
escape. This can be exploited by a modified guest device driver. It is
not exploitable from guest userspace since the guest kernel will handle
special files inside the guest instead of sending FUSE requests.
This patch fixes this issue by introducing the lo_inode_open() function
to check the file type before opening it. This is a short-term solution
because it does not prevent a compromised virtiofsd process from opening
device nodes on the host.
Restructure lo_create() to try O_CREAT | O_EXCL first. Note that O_CREAT
| O_EXCL does not follow symlinks, so O_NOFOLLOW masking is not
necessary here. If the file exists and the user did not specify O_EXCL,
open it via lo_do_open().
Reported-by: Alex Xu <alex@alxu.ca>
Fixes: CVE-2020-35517
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20210204150208.367837-4-stefanha@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
tools/virtiofsd/passthrough_ll.c | 144 ++++++++++++++++++++-----------
1 file changed, 92 insertions(+), 52 deletions(-)
diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
index 422ea75f..da4310e3 100644
--- a/tools/virtiofsd/passthrough_ll.c
+++ b/tools/virtiofsd/passthrough_ll.c
@@ -538,6 +538,38 @@ static int lo_fd(fuse_req_t req, fuse_ino_t ino)
return fd;
}
+/*
+ * Open a file descriptor for an inode. Returns -EBADF if the inode is not a
+ * regular file or a directory.
+ *
+ * Use this helper function instead of raw openat(2) to prevent security issues
+ * when a malicious client opens special files such as block device nodes.
+ * Symlink inodes are also rejected since symlinks must already have been
+ * traversed on the client side.
+ */
+static int lo_inode_open(struct lo_data *lo, struct lo_inode *inode,
+ int open_flags)
+{
+ g_autofree char *fd_str = g_strdup_printf("%d", inode->fd);
+ int fd;
+
+ if (!S_ISREG(inode->filetype) && !S_ISDIR(inode->filetype)) {
+ return -EBADF;
+ }
+
+ /*
+ * The file is a symlink so O_NOFOLLOW must be ignored. We checked earlier
+ * that the inode is not a special file but if an external process races
+ * with us then symlinks are traversed here. It is not possible to escape
+ * the shared directory since it is mounted as "/" though.
+ */
+ fd = openat(lo->proc_self_fd, fd_str, open_flags & ~O_NOFOLLOW);
+ if (fd < 0) {
+ return -errno;
+ }
+ return fd;
+}
+
static void lo_init(void *userdata, struct fuse_conn_info *conn)
{
struct lo_data *lo = (struct lo_data *)userdata;
@@ -791,9 +823,9 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr,
if (fi) {
truncfd = fd;
} else {
- sprintf(procname, "%i", ifd);
- truncfd = openat(lo->proc_self_fd, procname, O_RDWR);
+ truncfd = lo_inode_open(lo, inode, O_RDWR);
if (truncfd < 0) {
+ errno = -truncfd;
goto out_err;
}
}
@@ -897,7 +929,7 @@ static int lo_do_lookup(fuse_req_t req, fuse_ino_t parent, const char *name,
struct lo_inode *dir = lo_inode(req, parent);
if (inodep) {
- *inodep = NULL;
+ *inodep = NULL; /* in case there is an error */
}
/*
@@ -1728,19 +1760,26 @@ static void update_open_flags(int writeback, int allow_direct_io,
}
}
+/*
+ * Open a regular file, set up an fd mapping, and fill out the struct
+ * fuse_file_info for it. If existing_fd is not negative, use that fd instead
+ * opening a new one. Takes ownership of existing_fd.
+ *
+ * Returns 0 on success or a positive errno.
+ */
static int lo_do_open(struct lo_data *lo, struct lo_inode *inode,
- struct fuse_file_info *fi)
+ int existing_fd, struct fuse_file_info *fi)
{
- char buf[64];
ssize_t fh;
- int fd;
+ int fd = existing_fd;
update_open_flags(lo->writeback, lo->allow_direct_io, fi);
- sprintf(buf, "%i", inode->fd);
- fd = openat(lo->proc_self_fd, buf, fi->flags & ~O_NOFOLLOW);
- if (fd == -1) {
- return errno;
+ if (fd < 0) {
+ fd = lo_inode_open(lo, inode, fi->flags);
+ if (fd < 0) {
+ return -fd;
+ }
}
pthread_mutex_lock(&lo->mutex);
@@ -1763,9 +1802,10 @@ static int lo_do_open(struct lo_data *lo, struct lo_inode *inode,
static void lo_create(fuse_req_t req, fuse_ino_t parent, const char *name,
mode_t mode, struct fuse_file_info *fi)
{
- int fd;
+ int fd = -1;
struct lo_data *lo = lo_data(req);
struct lo_inode *parent_inode;
+ struct lo_inode *inode = NULL;
struct fuse_entry_param e;
int err;
struct lo_cred old = {};
@@ -1791,36 +1831,38 @@ static void lo_create(fuse_req_t req, fuse_ino_t parent, const char *name,
update_open_flags(lo->writeback, lo->allow_direct_io, fi);
- fd = openat(parent_inode->fd, name, (fi->flags | O_CREAT) & ~O_NOFOLLOW,
- mode);
+ /* Try to create a new file but don't open existing files */
+ fd = openat(parent_inode->fd, name, fi->flags | O_CREAT | O_EXCL, mode);
err = fd == -1 ? errno : 0;
- lo_restore_cred(&old);
- if (!err) {
- ssize_t fh;
+ lo_restore_cred(&old);
- pthread_mutex_lock(&lo->mutex);
- fh = lo_add_fd_mapping(lo, fd);
- pthread_mutex_unlock(&lo->mutex);
- if (fh == -1) {
- close(fd);
- err = ENOMEM;
- goto out;
- }
+ /* Ignore the error if file exists and O_EXCL was not given */
+ if (err && (err != EEXIST || (fi->flags & O_EXCL))) {
+ goto out;
+ }
- fi->fh = fh;
- err = lo_do_lookup(req, parent, name, &e, NULL);
+ err = lo_do_lookup(req, parent, name, &e, &inode);
+ if (err) {
+ goto out;
}
- if (lo->cache == CACHE_NONE) {
- fi->direct_io = 1;
- } else if (lo->cache == CACHE_ALWAYS) {
- fi->keep_cache = 1;
+
+ err = lo_do_open(lo, inode, fd, fi);
+ fd = -1; /* lo_do_open() takes ownership of fd */
+ if (err) {
+ /* Undo lo_do_lookup() nlookup ref */
+ unref_inode_lolocked(lo, inode, 1);
}
out:
+ lo_inode_put(lo, &inode);
lo_inode_put(lo, &parent_inode);
if (err) {
+ if (fd >= 0) {
+ close(fd);
+ }
+
fuse_reply_err(req, err);
} else {
fuse_reply_create(req, &e, fi);
@@ -1834,7 +1876,6 @@ static struct lo_inode_plock *lookup_create_plock_ctx(struct lo_data *lo,
pid_t pid, int *err)
{
struct lo_inode_plock *plock;
- char procname[64];
int fd;
plock =
@@ -1851,12 +1892,10 @@ static struct lo_inode_plock *lookup_create_plock_ctx(struct lo_data *lo,
}
/* Open another instance of file which can be used for ofd locks. */
- sprintf(procname, "%i", inode->fd);
-
/* TODO: What if file is not writable? */
- fd = openat(lo->proc_self_fd, procname, O_RDWR);
- if (fd == -1) {
- *err = errno;
+ fd = lo_inode_open(lo, inode, O_RDWR);
+ if (fd < 0) {
+ *err = -fd;
free(plock);
return NULL;
}
@@ -2003,7 +2042,7 @@ static void lo_open(fuse_req_t req, fuse_ino_t ino, struct fuse_file_info *fi)
return;
}
- err = lo_do_open(lo, inode, fi);
+ err = lo_do_open(lo, inode, -1, fi);
lo_inode_put(lo, &inode);
if (err) {
fuse_reply_err(req, err);
@@ -2059,39 +2098,40 @@ static void lo_flush(fuse_req_t req, fuse_ino_t ino, struct fuse_file_info *fi)
static void lo_fsync(fuse_req_t req, fuse_ino_t ino, int datasync,
struct fuse_file_info *fi)
{
+ struct lo_inode *inode = lo_inode(req, ino);
+ struct lo_data *lo = lo_data(req);
int res;
int fd;
- char *buf;
fuse_log(FUSE_LOG_DEBUG, "lo_fsync(ino=%" PRIu64 ", fi=0x%p)\n", ino,
(void *)fi);
- if (!fi) {
- struct lo_data *lo = lo_data(req);
-
- res = asprintf(&buf, "%i", lo_fd(req, ino));
- if (res == -1) {
- return (void)fuse_reply_err(req, errno);
- }
+ if (!inode) {
+ fuse_reply_err(req, EBADF);
+ return;
+ }
- fd = openat(lo->proc_self_fd, buf, O_RDWR);
- free(buf);
- if (fd == -1) {
- return (void)fuse_reply_err(req, errno);
+ if (!fi) {
+ fd = lo_inode_open(lo, inode, O_RDWR);
+ if (fd < 0) {
+ res = -fd;
+ goto out;
}
} else {
fd = lo_fi_fd(req, fi);
}
if (datasync) {
- res = fdatasync(fd);
+ res = fdatasync(fd) == -1 ? errno : 0;
} else {
- res = fsync(fd);
+ res = fsync(fd) == -1 ? errno : 0;
}
if (!fi) {
close(fd);
}
- fuse_reply_err(req, res == -1 ? errno : 0);
+out:
+ lo_inode_put(lo, &inode);
+ fuse_reply_err(req, res);
}
static void lo_read(fuse_req_t req, fuse_ino_t ino, size_t size, off_t offset,
--
2.29.2

31
tools/packaging/qemu/patches/5.0.x/0008-virtiofsd-Add-_llseek-to-the-seccomp-whitelist.patch Normal file
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@ -0,0 +1,31 @@
From a68a49b83f6c2694a080bb3761f566bd84b7ca26 Mon Sep 17 00:00:00 2001
From: Greg Kurz <groug@kaod.org>
Date: Thu, 4 Feb 2021 20:23:16 +0100
Subject: [PATCH] virtiofsd: Add _llseek to the seccomp whitelist
This is how glibc implements lseek(2) on POWER.
BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1917692
Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <20210121171540.1449777-1-groug@kaod.org>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
tools/virtiofsd/seccomp.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/tools/virtiofsd/seccomp.c b/tools/virtiofsd/seccomp.c
index 7f93fe87..57642ff8 100644
--- a/tools/virtiofsd/seccomp.c
+++ b/tools/virtiofsd/seccomp.c
@@ -68,6 +68,7 @@ static const int syscall_whitelist[] = {
SCMP_SYS(linkat),
SCMP_SYS(listxattr),
SCMP_SYS(lseek),
+ SCMP_SYS(_llseek), /* For POWER */
SCMP_SYS(madvise),
SCMP_SYS(mkdirat),
SCMP_SYS(mknodat),
--
2.29.2

33
tools/packaging/qemu/patches/5.0.x/0009-virtiofsd-Add-restart_syscall-to-the-seccomp-whiteli.patch Normal file
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@ -0,0 +1,33 @@
From c013c9a1d796d1feae143f02b3c654f0a42f7055 Mon Sep 17 00:00:00 2001
From: Greg Kurz <groug@kaod.org>
Date: Thu, 4 Feb 2021 20:24:28 +0100
Subject: [PATCH] virtiofsd: Add restart_syscall to the seccomp whitelist
This is how linux restarts some system calls after SIGSTOP/SIGCONT.
This is needed to avoid virtiofsd termination when resuming execution
under GDB for example.
Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <20210201193305.136390-1-groug@kaod.org>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
tools/virtiofsd/seccomp.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/tools/virtiofsd/seccomp.c b/tools/virtiofsd/seccomp.c
index 57642ff8..004f5026 100644
--- a/tools/virtiofsd/seccomp.c
+++ b/tools/virtiofsd/seccomp.c
@@ -91,6 +91,7 @@ static const int syscall_whitelist[] = {
SCMP_SYS(renameat),
SCMP_SYS(renameat2),
SCMP_SYS(removexattr),
+ SCMP_SYS(restart_syscall),
SCMP_SYS(rt_sigaction),
SCMP_SYS(rt_sigprocmask),
SCMP_SYS(rt_sigreturn),
--
2.29.2

104
tools/packaging/qemu/patches/5.1.x/0007-virtiofsd-Add-o-allow_direct_io-no_allow_direct_io-o.patch Normal file
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@ -0,0 +1,104 @@
From c5c8e946f8200de1c6d917949e98484908b43f21 Mon Sep 17 00:00:00 2001
From: Jiachen Zhang <zhangjiachen.jaycee@bytedance.com>
Date: Thu, 4 Feb 2021 22:11:28 +0100
Subject: [PATCH] virtiofsd: Add -o allow_direct_io|no_allow_direct_io options
Due to the commit 65da4539803373ec4eec97ffc49ee90083e56efd, the O_DIRECT
open flag of guest applications will be discarded by virtiofsd. While
this behavior makes it consistent with the virtio-9p scheme when guest
applications use direct I/O, we no longer have any chance to bypass the
host page cache.
Therefore, we add a flag 'allow_direct_io' to lo_data. If '-o
no_allow_direct_io' option is added, or none of '-o allow_direct_io' or
'-o no_allow_direct_io' is added, the 'allow_direct_io' will be set to
0, and virtiofsd discards O_DIRECT as before. If '-o allow_direct_io'
is added to the starting command-line, 'allow_direct_io' will be set to
1, so that the O_DIRECT flags will be retained and host page cache can
be bypassed.
Signed-off-by: Jiachen Zhang <zhangjiachen.jaycee@bytedance.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20200824105957.61265-1-zhangjiachen.jaycee@bytedance.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
tools/virtiofsd/passthrough_ll.c | 20 ++++++++++++++------
1 file changed, 14 insertions(+), 6 deletions(-)
diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
index 94e0de2d..289c9985 100644
--- a/tools/virtiofsd/passthrough_ll.c
+++ b/tools/virtiofsd/passthrough_ll.c
@@ -151,6 +151,7 @@ struct lo_data {
int timeout_set;
int readdirplus_set;
int readdirplus_clear;
+ int allow_direct_io;
struct lo_inode root;
GHashTable *inodes; /* protected by lo->mutex */
struct lo_map ino_map; /* protected by lo->mutex */
@@ -179,6 +180,8 @@ static const struct fuse_opt lo_opts[] = {
{ "cache=always", offsetof(struct lo_data, cache), CACHE_ALWAYS },
{ "readdirplus", offsetof(struct lo_data, readdirplus_set), 1 },
{ "no_readdirplus", offsetof(struct lo_data, readdirplus_clear), 1 },
+ { "allow_direct_io", offsetof(struct lo_data, allow_direct_io), 1 },
+ { "no_allow_direct_io", offsetof(struct lo_data, allow_direct_io), 0 },
FUSE_OPT_END
};
static bool use_syslog = false;
@@ -1516,7 +1519,8 @@ static void lo_releasedir(fuse_req_t req, fuse_ino_t ino,
fuse_reply_err(req, 0);
}
-static void update_open_flags(int writeback, struct fuse_file_info *fi)
+static void update_open_flags(int writeback, int allow_direct_io,
+ struct fuse_file_info *fi)
{
/*
* With writeback cache, kernel may send read requests even
@@ -1541,10 +1545,13 @@ static void update_open_flags(int writeback, struct fuse_file_info *fi)
/*
* O_DIRECT in guest should not necessarily mean bypassing page
- * cache on host as well. If somebody needs that behavior, it
- * probably should be a configuration knob in daemon.
+ * cache on host as well. Therefore, we discard it by default
+ * ('-o no_allow_direct_io'). If somebody needs that behavior,
+ * the '-o allow_direct_io' option should be set.
*/
- fi->flags &= ~O_DIRECT;
+ if (!allow_direct_io) {
+ fi->flags &= ~O_DIRECT;
+ }
}
static void lo_create(fuse_req_t req, fuse_ino_t parent, const char *name,
@@ -1576,7 +1583,7 @@ static void lo_create(fuse_req_t req, fuse_ino_t parent, const char *name,
goto out;
}
- update_open_flags(lo->writeback, fi);
+ update_open_flags(lo->writeback, lo->allow_direct_io, fi);
fd = openat(parent_inode->fd, name, (fi->flags | O_CREAT) & ~O_NOFOLLOW,
mode);
@@ -1786,7 +1793,7 @@ static void lo_open(fuse_req_t req, fuse_ino_t ino, struct fuse_file_info *fi)
fuse_log(FUSE_LOG_DEBUG, "lo_open(ino=%" PRIu64 ", flags=%d)\n", ino,
fi->flags);
- update_open_flags(lo->writeback, fi);
+ update_open_flags(lo->writeback, lo->allow_direct_io, fi);
sprintf(buf, "%i", lo_fd(req, ino));
fd = openat(lo->proc_self_fd, buf, fi->flags & ~O_NOFOLLOW);
@@ -2824,6 +2831,7 @@ int main(int argc, char *argv[])
.debug = 0,
.writeback = 0,
.posix_lock = 1,
+ .allow_direct_io = 0,
.proc_self_fd = -1,
};
struct lo_map_elem *root_elem;
--
2.29.2

145
tools/packaging/qemu/patches/5.1.x/0008-virtiofsd-extract-lo_do_open-from-lo_open.patch Normal file
View File

@ -0,0 +1,145 @@
From 04600a6b1ad6376e6da955a929196b9c19fa7f4a Mon Sep 17 00:00:00 2001
From: Stefan Hajnoczi <stefanha@redhat.com>
Date: Thu, 4 Feb 2021 20:16:42 +0100
Subject: [PATCH] virtiofsd: extract lo_do_open() from lo_open()
Both lo_open() and lo_create() have similar code to open a file. Extract
a common lo_do_open() function from lo_open() that will be used by
lo_create() in a later commit.
Since lo_do_open() does not otherwise need fuse_req_t req, convert
lo_add_fd_mapping() to use struct lo_data *lo instead.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20210204150208.367837-2-stefanha@redhat.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
tools/virtiofsd/passthrough_ll.c | 73 ++++++++++++++++++++------------
1 file changed, 46 insertions(+), 27 deletions(-)
diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
index 289c9985..eaec0c5a 100644
--- a/tools/virtiofsd/passthrough_ll.c
+++ b/tools/virtiofsd/passthrough_ll.c
@@ -442,17 +442,17 @@ static void lo_map_remove(struct lo_map *map, size_t key)
}
/* Assumes lo->mutex is held */
-static ssize_t lo_add_fd_mapping(fuse_req_t req, int fd)
+static ssize_t lo_add_fd_mapping(struct lo_data *lo, int fd)
{
struct lo_map_elem *elem;
- elem = lo_map_alloc_elem(&lo_data(req)->fd_map);
+ elem = lo_map_alloc_elem(&lo->fd_map);
if (!elem) {
return -1;
}
elem->fd = fd;
- return elem - lo_data(req)->fd_map.elems;
+ return elem - lo->fd_map.elems;
}
/* Assumes lo->mutex is held */
@@ -1554,6 +1554,38 @@ static void update_open_flags(int writeback, int allow_direct_io,
}
}
+static int lo_do_open(struct lo_data *lo, struct lo_inode *inode,
+ struct fuse_file_info *fi)
+{
+ char buf[64];
+ ssize_t fh;
+ int fd;
+
+ update_open_flags(lo->writeback, lo->allow_direct_io, fi);
+
+ sprintf(buf, "%i", inode->fd);
+ fd = openat(lo->proc_self_fd, buf, fi->flags & ~O_NOFOLLOW);
+ if (fd == -1) {
+ return errno;
+ }
+
+ pthread_mutex_lock(&lo->mutex);
+ fh = lo_add_fd_mapping(lo, fd);
+ pthread_mutex_unlock(&lo->mutex);
+ if (fh == -1) {
+ close(fd);
+ return ENOMEM;
+ }
+
+ fi->fh = fh;
+ if (lo->cache == CACHE_NONE) {
+ fi->direct_io = 1;
+ } else if (lo->cache == CACHE_ALWAYS) {
+ fi->keep_cache = 1;
+ }
+ return 0;
+}
+
static void lo_create(fuse_req_t req, fuse_ino_t parent, const char *name,
mode_t mode, struct fuse_file_info *fi)
{
@@ -1594,7 +1626,7 @@ static void lo_create(fuse_req_t req, fuse_ino_t parent, const char *name,
ssize_t fh;
pthread_mutex_lock(&lo->mutex);
- fh = lo_add_fd_mapping(req, fd);
+ fh = lo_add_fd_mapping(lo, fd);
pthread_mutex_unlock(&lo->mutex);
if (fh == -1) {
close(fd);
@@ -1785,38 +1817,25 @@ static void lo_fsyncdir(fuse_req_t req, fuse_ino_t ino, int datasync,
static void lo_open(fuse_req_t req, fuse_ino_t ino, struct fuse_file_info *fi)
{
- int fd;
- ssize_t fh;
- char buf[64];
struct lo_data *lo = lo_data(req);
+ struct lo_inode *inode = lo_inode(req, ino);
+ int err;
fuse_log(FUSE_LOG_DEBUG, "lo_open(ino=%" PRIu64 ", flags=%d)\n", ino,
fi->flags);
- update_open_flags(lo->writeback, lo->allow_direct_io, fi);
-
- sprintf(buf, "%i", lo_fd(req, ino));
- fd = openat(lo->proc_self_fd, buf, fi->flags & ~O_NOFOLLOW);
- if (fd == -1) {
- return (void)fuse_reply_err(req, errno);
- }
-
- pthread_mutex_lock(&lo->mutex);
- fh = lo_add_fd_mapping(req, fd);
- pthread_mutex_unlock(&lo->mutex);
- if (fh == -1) {
- close(fd);
- fuse_reply_err(req, ENOMEM);
+ if (!inode) {
+ fuse_reply_err(req, EBADF);
return;
}
- fi->fh = fh;
- if (lo->cache == CACHE_NONE) {
- fi->direct_io = 1;
- } else if (lo->cache == CACHE_ALWAYS) {
- fi->keep_cache = 1;
+ err = lo_do_open(lo, inode, fi);
+ lo_inode_put(lo, &inode);
+ if (err) {
+ fuse_reply_err(req, err);
+ } else {
+ fuse_reply_open(req, fi);
}
- fuse_reply_open(req, fi);
}
static void lo_release(fuse_req_t req, fuse_ino_t ino,
--
2.29.2

109
tools/packaging/qemu/patches/5.1.x/0009-virtiofsd-optionally-return-inode-pointer-from-lo_do.patch Normal file
View File

@ -0,0 +1,109 @@
From 51b4b251442ade9163c9c9f953e5db00340ab3f1 Mon Sep 17 00:00:00 2001
From: Stefan Hajnoczi <stefanha@redhat.com>
Date: Thu, 4 Feb 2021 15:02:07 +0000
Subject: [PATCH] virtiofsd: optionally return inode pointer from
lo_do_lookup()
lo_do_lookup() finds an existing inode or allocates a new one. It
increments nlookup so that the inode stays alive until the client
releases it.
Existing callers don't need the struct lo_inode so the function doesn't
return it. Extend the function to optionally return the inode. The next
commit will need it.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Message-Id: <20210204150208.367837-3-stefanha@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
tools/virtiofsd/passthrough_ll.c | 29 +++++++++++++++++++++--------
1 file changed, 21 insertions(+), 8 deletions(-)
diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
index eaec0c5a..a874f509 100644
--- a/tools/virtiofsd/passthrough_ll.c
+++ b/tools/virtiofsd/passthrough_ll.c
@@ -752,11 +752,13 @@ static void posix_locks_value_destroy(gpointer data)
}
/*
- * Increments nlookup and caller must release refcount using
- * lo_inode_put(&parent).
+ * Increments nlookup on the inode on success. unref_inode_lolocked() must be
+ * called eventually to decrement nlookup again. If inodep is non-NULL, the
+ * inode pointer is stored and the caller must call lo_inode_put().
*/
static int lo_do_lookup(fuse_req_t req, fuse_ino_t parent, const char *name,
- struct fuse_entry_param *e)
+ struct fuse_entry_param *e,
+ struct lo_inode **inodep)
{
int newfd;
int res;
@@ -765,6 +767,10 @@ static int lo_do_lookup(fuse_req_t req, fuse_ino_t parent, const char *name,
struct lo_inode *inode = NULL;
struct lo_inode *dir = lo_inode(req, parent);
+ if (inodep) {
+ *inodep = NULL;
+ }
+
/*
* name_to_handle_at() and open_by_handle_at() can reach here with fuse
* mount point in guest, but we don't have its inode info in the
@@ -825,7 +831,14 @@ static int lo_do_lookup(fuse_req_t req, fuse_ino_t parent, const char *name,
pthread_mutex_unlock(&lo->mutex);
}
e->ino = inode->fuse_ino;
- lo_inode_put(lo, &inode);
+
+ /* Transfer ownership of inode pointer to caller or drop it */
+ if (inodep) {
+ *inodep = inode;
+ } else {
+ lo_inode_put(lo, &inode);
+ }
+
lo_inode_put(lo, &dir);
fuse_log(FUSE_LOG_DEBUG, " %lli/%s -> %lli\n", (unsigned long long)parent,
@@ -860,7 +873,7 @@ static void lo_lookup(fuse_req_t req, fuse_ino_t parent, const char *name)
return;
}
- err = lo_do_lookup(req, parent, name, &e);
+ err = lo_do_lookup(req, parent, name, &e, NULL);
if (err) {
fuse_reply_err(req, err);
} else {
@@ -968,7 +981,7 @@ static void lo_mknod_symlink(fuse_req_t req, fuse_ino_t parent,
goto out;
}
- saverr = lo_do_lookup(req, parent, name, &e);
+ saverr = lo_do_lookup(req, parent, name, &e, NULL);
if (saverr) {
goto out;
}
@@ -1437,7 +1450,7 @@ static void lo_do_readdir(fuse_req_t req, fuse_ino_t ino, size_t size,
if (plus) {
if (!is_dot_or_dotdot(name)) {
- err = lo_do_lookup(req, ino, name, &e);
+ err = lo_do_lookup(req, ino, name, &e, NULL);
if (err) {
goto error;
}
@@ -1635,7 +1648,7 @@ static void lo_create(fuse_req_t req, fuse_ino_t parent, const char *name,
}
fi->fh = fh;
- err = lo_do_lookup(req, parent, name, &e);
+ err = lo_do_lookup(req, parent, name, &e, NULL);
}
if (lo->cache == CACHE_NONE) {
fi->direct_io = 1;
--
2.29.2

298
tools/packaging/qemu/patches/5.1.x/0010-virtiofsd-prevent-opening-of-special-files-CVE-2020-.patch Normal file
View File

@ -0,0 +1,298 @@
From 0d3f3e7b142814bbd6cda096cb52891cca983c92 Mon Sep 17 00:00:00 2001
From: Stefan Hajnoczi <stefanha@redhat.com>
Date: Thu, 4 Feb 2021 20:20:00 +0100
Subject: [PATCH] virtiofsd: prevent opening of special files (CVE-2020-35517)
A well-behaved FUSE client does not attempt to open special files with
FUSE_OPEN because they are handled on the client side (e.g. device nodes
are handled by client-side device drivers).
The check to prevent virtiofsd from opening special files is missing in
a few cases, most notably FUSE_OPEN. A malicious client can cause
virtiofsd to open a device node, potentially allowing the guest to
escape. This can be exploited by a modified guest device driver. It is
not exploitable from guest userspace since the guest kernel will handle
special files inside the guest instead of sending FUSE requests.
This patch fixes this issue by introducing the lo_inode_open() function
to check the file type before opening it. This is a short-term solution
because it does not prevent a compromised virtiofsd process from opening
device nodes on the host.
Restructure lo_create() to try O_CREAT | O_EXCL first. Note that O_CREAT
| O_EXCL does not follow symlinks, so O_NOFOLLOW masking is not
necessary here. If the file exists and the user did not specify O_EXCL,
open it via lo_do_open().
Reported-by: Alex Xu <alex@alxu.ca>
Fixes: CVE-2020-35517
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20210204150208.367837-4-stefanha@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
tools/virtiofsd/passthrough_ll.c | 144 ++++++++++++++++++++-----------
1 file changed, 92 insertions(+), 52 deletions(-)
diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
index a874f509..41ff708a 100644
--- a/tools/virtiofsd/passthrough_ll.c
+++ b/tools/virtiofsd/passthrough_ll.c
@@ -538,6 +538,38 @@ static int lo_fd(fuse_req_t req, fuse_ino_t ino)
return fd;
}
+/*
+ * Open a file descriptor for an inode. Returns -EBADF if the inode is not a
+ * regular file or a directory.
+ *
+ * Use this helper function instead of raw openat(2) to prevent security issues
+ * when a malicious client opens special files such as block device nodes.
+ * Symlink inodes are also rejected since symlinks must already have been
+ * traversed on the client side.
+ */
+static int lo_inode_open(struct lo_data *lo, struct lo_inode *inode,
+ int open_flags)
+{
+ g_autofree char *fd_str = g_strdup_printf("%d", inode->fd);
+ int fd;
+
+ if (!S_ISREG(inode->filetype) && !S_ISDIR(inode->filetype)) {
+ return -EBADF;
+ }
+
+ /*
+ * The file is a symlink so O_NOFOLLOW must be ignored. We checked earlier
+ * that the inode is not a special file but if an external process races
+ * with us then symlinks are traversed here. It is not possible to escape
+ * the shared directory since it is mounted as "/" though.
+ */
+ fd = openat(lo->proc_self_fd, fd_str, open_flags & ~O_NOFOLLOW);
+ if (fd < 0) {
+ return -errno;
+ }
+ return fd;
+}
+
static void lo_init(void *userdata, struct fuse_conn_info *conn)
{
struct lo_data *lo = (struct lo_data *)userdata;
@@ -661,9 +693,9 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr,
if (fi) {
truncfd = fd;
} else {
- sprintf(procname, "%i", ifd);
- truncfd = openat(lo->proc_self_fd, procname, O_RDWR);
+ truncfd = lo_inode_open(lo, inode, O_RDWR);
if (truncfd < 0) {
+ errno = -truncfd;
goto out_err;
}
}
@@ -768,7 +800,7 @@ static int lo_do_lookup(fuse_req_t req, fuse_ino_t parent, const char *name,
struct lo_inode *dir = lo_inode(req, parent);
if (inodep) {
- *inodep = NULL;
+ *inodep = NULL; /* in case there is an error */
}
/*
@@ -1567,19 +1599,26 @@ static void update_open_flags(int writeback, int allow_direct_io,
}
}
+/*
+ * Open a regular file, set up an fd mapping, and fill out the struct
+ * fuse_file_info for it. If existing_fd is not negative, use that fd instead
+ * opening a new one. Takes ownership of existing_fd.
+ *
+ * Returns 0 on success or a positive errno.
+ */
static int lo_do_open(struct lo_data *lo, struct lo_inode *inode,
- struct fuse_file_info *fi)
+ int existing_fd, struct fuse_file_info *fi)
{
- char buf[64];
ssize_t fh;
- int fd;
+ int fd = existing_fd;
update_open_flags(lo->writeback, lo->allow_direct_io, fi);
- sprintf(buf, "%i", inode->fd);
- fd = openat(lo->proc_self_fd, buf, fi->flags & ~O_NOFOLLOW);
- if (fd == -1) {
- return errno;
+ if (fd < 0) {
+ fd = lo_inode_open(lo, inode, fi->flags);
+ if (fd < 0) {
+ return -fd;
+ }
}
pthread_mutex_lock(&lo->mutex);
@@ -1602,9 +1641,10 @@ static int lo_do_open(struct lo_data *lo, struct lo_inode *inode,
static void lo_create(fuse_req_t req, fuse_ino_t parent, const char *name,
mode_t mode, struct fuse_file_info *fi)
{
- int fd;
+ int fd = -1;
struct lo_data *lo = lo_data(req);
struct lo_inode *parent_inode;
+ struct lo_inode *inode = NULL;
struct fuse_entry_param e;
int err;
struct lo_cred old = {};
@@ -1630,36 +1670,38 @@ static void lo_create(fuse_req_t req, fuse_ino_t parent, const char *name,
update_open_flags(lo->writeback, lo->allow_direct_io, fi);
- fd = openat(parent_inode->fd, name, (fi->flags | O_CREAT) & ~O_NOFOLLOW,
- mode);
+ /* Try to create a new file but don't open existing files */
+ fd = openat(parent_inode->fd, name, fi->flags | O_CREAT | O_EXCL, mode);
err = fd == -1 ? errno : 0;
- lo_restore_cred(&old);
- if (!err) {
- ssize_t fh;
+ lo_restore_cred(&old);
- pthread_mutex_lock(&lo->mutex);
- fh = lo_add_fd_mapping(lo, fd);
- pthread_mutex_unlock(&lo->mutex);
- if (fh == -1) {
- close(fd);
- err = ENOMEM;
- goto out;
- }
+ /* Ignore the error if file exists and O_EXCL was not given */
+ if (err && (err != EEXIST || (fi->flags & O_EXCL))) {
+ goto out;
+ }
- fi->fh = fh;
- err = lo_do_lookup(req, parent, name, &e, NULL);
+ err = lo_do_lookup(req, parent, name, &e, &inode);
+ if (err) {
+ goto out;
}
- if (lo->cache == CACHE_NONE) {
- fi->direct_io = 1;
- } else if (lo->cache == CACHE_ALWAYS) {
- fi->keep_cache = 1;
+
+ err = lo_do_open(lo, inode, fd, fi);
+ fd = -1; /* lo_do_open() takes ownership of fd */
+ if (err) {
+ /* Undo lo_do_lookup() nlookup ref */
+ unref_inode_lolocked(lo, inode, 1);
}
out:
+ lo_inode_put(lo, &inode);
lo_inode_put(lo, &parent_inode);
if (err) {
+ if (fd >= 0) {
+ close(fd);
+ }
+
fuse_reply_err(req, err);
} else {
fuse_reply_create(req, &e, fi);
@@ -1673,7 +1715,6 @@ static struct lo_inode_plock *lookup_create_plock_ctx(struct lo_data *lo,
pid_t pid, int *err)
{
struct lo_inode_plock *plock;
- char procname[64];
int fd;
plock =
@@ -1690,12 +1731,10 @@ static struct lo_inode_plock *lookup_create_plock_ctx(struct lo_data *lo,
}
/* Open another instance of file which can be used for ofd locks. */
- sprintf(procname, "%i", inode->fd);
-
/* TODO: What if file is not writable? */
- fd = openat(lo->proc_self_fd, procname, O_RDWR);
- if (fd == -1) {
- *err = errno;
+ fd = lo_inode_open(lo, inode, O_RDWR);
+ if (fd < 0) {
+ *err = -fd;
free(plock);
return NULL;
}
@@ -1842,7 +1881,7 @@ static void lo_open(fuse_req_t req, fuse_ino_t ino, struct fuse_file_info *fi)
return;
}
- err = lo_do_open(lo, inode, fi);
+ err = lo_do_open(lo, inode, -1, fi);
lo_inode_put(lo, &inode);
if (err) {
fuse_reply_err(req, err);
@@ -1898,39 +1937,40 @@ static void lo_flush(fuse_req_t req, fuse_ino_t ino, struct fuse_file_info *fi)
static void lo_fsync(fuse_req_t req, fuse_ino_t ino, int datasync,
struct fuse_file_info *fi)
{
+ struct lo_inode *inode = lo_inode(req, ino);
+ struct lo_data *lo = lo_data(req);
int res;
int fd;
- char *buf;
fuse_log(FUSE_LOG_DEBUG, "lo_fsync(ino=%" PRIu64 ", fi=0x%p)\n", ino,
(void *)fi);
- if (!fi) {
- struct lo_data *lo = lo_data(req);
-
- res = asprintf(&buf, "%i", lo_fd(req, ino));
- if (res == -1) {
- return (void)fuse_reply_err(req, errno);
- }
+ if (!inode) {
+ fuse_reply_err(req, EBADF);
+ return;
+ }
- fd = openat(lo->proc_self_fd, buf, O_RDWR);
- free(buf);
- if (fd == -1) {
- return (void)fuse_reply_err(req, errno);
+ if (!fi) {
+ fd = lo_inode_open(lo, inode, O_RDWR);
+ if (fd < 0) {
+ res = -fd;
+ goto out;
}
} else {
fd = lo_fi_fd(req, fi);
}
if (datasync) {
- res = fdatasync(fd);
+ res = fdatasync(fd) == -1 ? errno : 0;
} else {
- res = fsync(fd);
+ res = fsync(fd) == -1 ? errno : 0;
}
if (!fi) {
close(fd);
}
- fuse_reply_err(req, res == -1 ? errno : 0);
+out:
+ lo_inode_put(lo, &inode);
+ fuse_reply_err(req, res);
}
static void lo_read(fuse_req_t req, fuse_ino_t ino, size_t size, off_t offset,
--
2.29.2

31
tools/packaging/qemu/patches/5.1.x/0011-virtiofsd-Add-_llseek-to-the-seccomp-whitelist.patch Normal file
View File

@ -0,0 +1,31 @@
From 7670d5d5061a8d959a367bdd9d86b6b97a3bf4e9 Mon Sep 17 00:00:00 2001
From: Greg Kurz <groug@kaod.org>
Date: Thu, 4 Feb 2021 20:23:16 +0100
Subject: [PATCH] virtiofsd: Add _llseek to the seccomp whitelist
This is how glibc implements lseek(2) on POWER.
BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1917692
Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <20210121171540.1449777-1-groug@kaod.org>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
tools/virtiofsd/seccomp.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/tools/virtiofsd/seccomp.c b/tools/virtiofsd/seccomp.c
index 7f93fe87..57642ff8 100644
--- a/tools/virtiofsd/seccomp.c
+++ b/tools/virtiofsd/seccomp.c
@@ -68,6 +68,7 @@ static const int syscall_whitelist[] = {
SCMP_SYS(linkat),
SCMP_SYS(listxattr),
SCMP_SYS(lseek),
+ SCMP_SYS(_llseek), /* For POWER */
SCMP_SYS(madvise),
SCMP_SYS(mkdirat),
SCMP_SYS(mknodat),
--
2.29.2

33
tools/packaging/qemu/patches/5.1.x/0012-virtiofsd-Add-restart_syscall-to-the-seccomp-whiteli.patch Normal file
View File

@ -0,0 +1,33 @@
From 82bc7d7c11ff868ca9b0f663e847f535eab4e3ac Mon Sep 17 00:00:00 2001
From: Greg Kurz <groug@kaod.org>
Date: Thu, 4 Feb 2021 20:24:28 +0100
Subject: [PATCH] virtiofsd: Add restart_syscall to the seccomp whitelist
This is how linux restarts some system calls after SIGSTOP/SIGCONT.
This is needed to avoid virtiofsd termination when resuming execution
under GDB for example.
Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <20210201193305.136390-1-groug@kaod.org>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
tools/virtiofsd/seccomp.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/tools/virtiofsd/seccomp.c b/tools/virtiofsd/seccomp.c
index 57642ff8..004f5026 100644
--- a/tools/virtiofsd/seccomp.c
+++ b/tools/virtiofsd/seccomp.c
@@ -91,6 +91,7 @@ static const int syscall_whitelist[] = {
SCMP_SYS(renameat),
SCMP_SYS(renameat2),
SCMP_SYS(removexattr),
+ SCMP_SYS(restart_syscall),
SCMP_SYS(rt_sigaction),
SCMP_SYS(rt_sigprocmask),
SCMP_SYS(rt_sigreturn),
--
2.29.2