[PULL 0/5] virtiofs queue: Security fix

[PULL 0/5] virtiofs queue: Security fix

[Dr. David Alan Gilbert (git)]

From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

The following changes since commit 1ba089f2255bfdb071be3ce6ac6c3069e8012179:

  Merge remote-tracking branch 'remotes/armbru/tags/pull-qmp-2021-02-04' into staging (2021-02-04 14:15:35 +0000)

are available in the Git repository at:

  https://gitlab.com/dagrh/qemu.git tags/pull-virtiofs-20210204

for you to fetch changes up to cf269ff8032392bbdd700e7bfd21823ad9eee3a9:

  virtiofsd: Add restart_syscall to the seccomp whitelist (2021-02-04 17:50:08 +0000)

----------------------------------------------------------------
virtiofs: Security pull 2021-02-04

This contains an important CVE fix for virtiofsd,
together with two fixes for over-eager seccomp rules.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

----------------------------------------------------------------
Greg Kurz (2):
      virtiofsd: Add _llseek to the seccomp whitelist
      virtiofsd: Add restart_syscall to the seccomp whitelist

Stefan Hajnoczi (3):
      virtiofsd: extract lo_do_open() from lo_open()
      virtiofsd: optionally return inode pointer from lo_do_lookup()
      virtiofsd: prevent opening of special files (CVE-2020-35517)

 tools/virtiofsd/passthrough_ll.c      | 224 ++++++++++++++++++++++------------
 tools/virtiofsd/passthrough_seccomp.c |   2 +
 2 files changed, 150 insertions(+), 76 deletions(-)

[Virtio-fs] [PULL 0/5] virtiofs queue: Security fix

[Dr. David Alan Gilbert (git)]

From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

The following changes since commit 1ba089f2255bfdb071be3ce6ac6c3069e8012179:

  Merge remote-tracking branch 'remotes/armbru/tags/pull-qmp-2021-02-04' into staging (2021-02-04 14:15:35 +0000)

are available in the Git repository at:

  https://gitlab.com/dagrh/qemu.git tags/pull-virtiofs-20210204

for you to fetch changes up to cf269ff8032392bbdd700e7bfd21823ad9eee3a9:

  virtiofsd: Add restart_syscall to the seccomp whitelist (2021-02-04 17:50:08 +0000)

----------------------------------------------------------------
virtiofs: Security pull 2021-02-04

This contains an important CVE fix for virtiofsd,
together with two fixes for over-eager seccomp rules.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

----------------------------------------------------------------
Greg Kurz (2):
      virtiofsd: Add _llseek to the seccomp whitelist
      virtiofsd: Add restart_syscall to the seccomp whitelist

Stefan Hajnoczi (3):
      virtiofsd: extract lo_do_open() from lo_open()
      virtiofsd: optionally return inode pointer from lo_do_lookup()
      virtiofsd: prevent opening of special files (CVE-2020-35517)

 tools/virtiofsd/passthrough_ll.c      | 224 ++++++++++++++++++++++------------
 tools/virtiofsd/passthrough_seccomp.c |   2 +
 2 files changed, 150 insertions(+), 76 deletions(-)

[PULL 1/5] virtiofsd: extract lo_do_open() from lo_open()

[Dr. David Alan Gilbert (git)]

From: Stefan Hajnoczi <stefanha@redhat.com>

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 5fb36d9407..f14fa5124d 100644
--- a/tools/virtiofsd/passthrough_ll.c
+++ b/tools/virtiofsd/passthrough_ll.c
@@ -459,17 +459,17 @@ 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 */
@@ -1651,6 +1651,38 @@ 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)
 {
@@ -1691,7 +1723,7 @@ 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);
@@ -1892,38 +1924,25 @@ 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

[Virtio-fs] [PULL 1/5] virtiofsd: extract lo_do_open() from lo_open()

[Dr. David Alan Gilbert (git)]

From: Stefan Hajnoczi <stefanha@redhat.com>

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 5fb36d9407..f14fa5124d 100644
--- a/tools/virtiofsd/passthrough_ll.c
+++ b/tools/virtiofsd/passthrough_ll.c
@@ -459,17 +459,17 @@ 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 */
@@ -1651,6 +1651,38 @@ 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)
 {
@@ -1691,7 +1723,7 @@ 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);
@@ -1892,38 +1924,25 @@ 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

[PULL 2/5] virtiofsd: optionally return inode pointer from lo_do_lookup()

[Dr. David Alan Gilbert (git)]

From: Stefan Hajnoczi <stefanha@redhat.com>

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 f14fa5124d..aa35fc6ba5 100644
--- a/tools/virtiofsd/passthrough_ll.c
+++ b/tools/virtiofsd/passthrough_ll.c
@@ -831,11 +831,13 @@ static int do_statx(struct lo_data *lo, int dirfd, const char *pathname,
 }
 
 /*
- * 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;
@@ -845,6 +847,10 @@ 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
@@ -913,7 +919,14 @@ 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,
@@ -948,7 +961,7 @@ 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 {
@@ -1056,7 +1069,7 @@ 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;
     }
@@ -1534,7 +1547,7 @@ 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;
                 }
@@ -1732,7 +1745,7 @@ 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

[Virtio-fs] [PULL 2/5] virtiofsd: optionally return inode pointer from lo_do_lookup()

[Dr. David Alan Gilbert (git)]

From: Stefan Hajnoczi <stefanha@redhat.com>

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 f14fa5124d..aa35fc6ba5 100644
--- a/tools/virtiofsd/passthrough_ll.c
+++ b/tools/virtiofsd/passthrough_ll.c
@@ -831,11 +831,13 @@ static int do_statx(struct lo_data *lo, int dirfd, const char *pathname,
 }
 
 /*
- * 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;
@@ -845,6 +847,10 @@ 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
@@ -913,7 +919,14 @@ 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,
@@ -948,7 +961,7 @@ 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 {
@@ -1056,7 +1069,7 @@ 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;
     }
@@ -1534,7 +1547,7 @@ 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;
                 }
@@ -1732,7 +1745,7 @@ 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

[PULL 3/5] virtiofsd: prevent opening of special files (CVE-2020-35517)

[Dr. David Alan Gilbert (git)]

From: Stefan Hajnoczi <stefanha@redhat.com>

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 aa35fc6ba5..147b59338a 100644
--- a/tools/virtiofsd/passthrough_ll.c
+++ b/tools/virtiofsd/passthrough_ll.c
@@ -555,6 +555,38 @@ 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;
@@ -684,9 +716,9 @@ 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;
             }
         }
@@ -848,7 +880,7 @@ 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 */
     }
 
     /*
@@ -1664,19 +1696,26 @@ 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);
@@ -1699,9 +1738,10 @@ 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 = {};
@@ -1727,36 +1767,38 @@ 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);
@@ -1770,7 +1812,6 @@ 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 =
@@ -1787,12 +1828,10 @@ 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;
     }
@@ -1949,7 +1988,7 @@ 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);
@@ -2014,39 +2053,40 @@ 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

[Virtio-fs] [PULL 3/5] virtiofsd: prevent opening of special files (CVE-2020-35517)

[Dr. David Alan Gilbert (git)]

From: Stefan Hajnoczi <stefanha@redhat.com>

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 aa35fc6ba5..147b59338a 100644
--- a/tools/virtiofsd/passthrough_ll.c
+++ b/tools/virtiofsd/passthrough_ll.c
@@ -555,6 +555,38 @@ 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;
@@ -684,9 +716,9 @@ 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;
             }
         }
@@ -848,7 +880,7 @@ 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 */
     }
 
     /*
@@ -1664,19 +1696,26 @@ 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);
@@ -1699,9 +1738,10 @@ 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 = {};
@@ -1727,36 +1767,38 @@ 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);
@@ -1770,7 +1812,6 @@ 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 =
@@ -1787,12 +1828,10 @@ 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;
     }
@@ -1949,7 +1988,7 @@ 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);
@@ -2014,39 +2053,40 @@ 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

[PULL 4/5] virtiofsd: Add _llseek to the seccomp whitelist

[Dr. David Alan Gilbert (git)]

From: Greg Kurz <groug@kaod.org>

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/passthrough_seccomp.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/virtiofsd/passthrough_seccomp.c b/tools/virtiofsd/passthrough_seccomp.c
index a60d7da4b4..1ecf5bf318 100644
--- a/tools/virtiofsd/passthrough_seccomp.c
+++ b/tools/virtiofsd/passthrough_seccomp.c
@@ -65,6 +65,7 @@ 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

[Virtio-fs] [PULL 4/5] virtiofsd: Add _llseek to the seccomp whitelist

[Dr. David Alan Gilbert (git)]

From: Greg Kurz <groug@kaod.org>

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/passthrough_seccomp.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/virtiofsd/passthrough_seccomp.c b/tools/virtiofsd/passthrough_seccomp.c
index a60d7da4b4..1ecf5bf318 100644
--- a/tools/virtiofsd/passthrough_seccomp.c
+++ b/tools/virtiofsd/passthrough_seccomp.c
@@ -65,6 +65,7 @@ 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

[PULL 5/5] virtiofsd: Add restart_syscall to the seccomp whitelist

[Dr. David Alan Gilbert (git)]

From: Greg Kurz <groug@kaod.org>

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/passthrough_seccomp.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/virtiofsd/passthrough_seccomp.c b/tools/virtiofsd/passthrough_seccomp.c
index 1ecf5bf318..ea852e2e33 100644
--- a/tools/virtiofsd/passthrough_seccomp.c
+++ b/tools/virtiofsd/passthrough_seccomp.c
@@ -89,6 +89,7 @@ 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

[Virtio-fs] [PULL 5/5] virtiofsd: Add restart_syscall to the seccomp whitelist

[Dr. David Alan Gilbert (git)]

From: Greg Kurz <groug@kaod.org>

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/passthrough_seccomp.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tools/virtiofsd/passthrough_seccomp.c b/tools/virtiofsd/passthrough_seccomp.c
index 1ecf5bf318..ea852e2e33 100644
--- a/tools/virtiofsd/passthrough_seccomp.c
+++ b/tools/virtiofsd/passthrough_seccomp.c
@@ -89,6 +89,7 @@ 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

Re: [PULL 0/5] virtiofs queue: Security fix

[no-reply]

Patchew URL: https://patchew.org/QEMU/20210204183439.546918-1-dgilbert@redhat.com/



Hi,

This series seems to have some coding style problems. See output below for
more information:

Type: series
Message-id: 20210204183439.546918-1-dgilbert@redhat.com
Subject: [PULL 0/5] virtiofs queue: Security fix

=== TEST SCRIPT BEGIN ===
#!/bin/bash
git rev-parse base > /dev/null || exit 0
git config --local diff.renamelimit 0
git config --local diff.renames True
git config --local diff.algorithm histogram
./scripts/checkpatch.pl --mailback base..
=== TEST SCRIPT END ===

Updating 3c8cf5a9c21ff8782164d1def7f44bd888713384
From https://github.com/patchew-project/qemu
 * [new tag]         patchew/20210204183439.546918-1-dgilbert@redhat.com -> patchew/20210204183439.546918-1-dgilbert@redhat.com
Switched to a new branch 'test'
cc58a0c virtiofsd: Add restart_syscall to the seccomp whitelist
bc881ed virtiofsd: Add _llseek to the seccomp whitelist
449b30f virtiofsd: prevent opening of special files (CVE-2020-35517)
5da12fe virtiofsd: optionally return inode pointer from lo_do_lookup()
3690387 virtiofsd: extract lo_do_open() from lo_open()

=== OUTPUT BEGIN ===
1/5 Checking commit 3690387a3bc2 (virtiofsd: extract lo_do_open() from lo_open())
ERROR: return of an errno should typically be -ve (return -ENOMEM)
#72: FILE: tools/virtiofsd/passthrough_ll.c:1674:
+        return ENOMEM;

total: 1 errors, 0 warnings, 114 lines checked

Patch 1/5 has style problems, please review.  If any of these errors
are false positives report them to the maintainer, see
CHECKPATCH in MAINTAINERS.

2/5 Checking commit 5da12fe61f50 (virtiofsd: optionally return inode pointer from lo_do_lookup())
3/5 Checking commit 449b30fcc7be (virtiofsd: prevent opening of special files (CVE-2020-35517))
4/5 Checking commit bc881ed54ee8 (virtiofsd: Add _llseek to the seccomp whitelist)
5/5 Checking commit cc58a0c7f1a0 (virtiofsd: Add restart_syscall to the seccomp whitelist)
=== OUTPUT END ===

Test command exited with code: 1


The full log is available at
http://patchew.org/logs/20210204183439.546918-1-dgilbert@redhat.com/testing.checkpatch/?type=message.
---
Email generated automatically by Patchew [https://patchew.org/].
Please send your feedback to patchew-devel@redhat.com

Re: [Virtio-fs] [PULL 0/5] virtiofs queue: Security fix

[no-reply]

Patchew URL: https://patchew.org/QEMU/20210204183439.546918-1-dgilbert@redhat.com/



Hi,

This series seems to have some coding style problems. See output below for
more information:

Type: series
Message-id: 20210204183439.546918-1-dgilbert@redhat.com
Subject: [PULL 0/5] virtiofs queue: Security fix

=== TEST SCRIPT BEGIN ===
#!/bin/bash
git rev-parse base > /dev/null || exit 0
git config --local diff.renamelimit 0
git config --local diff.renames True
git config --local diff.algorithm histogram
./scripts/checkpatch.pl --mailback base..
=== TEST SCRIPT END ===

Updating 3c8cf5a9c21ff8782164d1def7f44bd888713384
>From https://github.com/patchew-project/qemu
 * [new tag]         patchew/20210204183439.546918-1-dgilbert@redhat.com -> patchew/20210204183439.546918-1-dgilbert@redhat.com
Switched to a new branch 'test'
cc58a0c virtiofsd: Add restart_syscall to the seccomp whitelist
bc881ed virtiofsd: Add _llseek to the seccomp whitelist
449b30f virtiofsd: prevent opening of special files (CVE-2020-35517)
5da12fe virtiofsd: optionally return inode pointer from lo_do_lookup()
3690387 virtiofsd: extract lo_do_open() from lo_open()

=== OUTPUT BEGIN ===
1/5 Checking commit 3690387a3bc2 (virtiofsd: extract lo_do_open() from lo_open())
ERROR: return of an errno should typically be -ve (return -ENOMEM)
#72: FILE: tools/virtiofsd/passthrough_ll.c:1674:
+        return ENOMEM;

total: 1 errors, 0 warnings, 114 lines checked

Patch 1/5 has style problems, please review.  If any of these errors
are false positives report them to the maintainer, see
CHECKPATCH in MAINTAINERS.

2/5 Checking commit 5da12fe61f50 (virtiofsd: optionally return inode pointer from lo_do_lookup())
3/5 Checking commit 449b30fcc7be (virtiofsd: prevent opening of special files (CVE-2020-35517))
4/5 Checking commit bc881ed54ee8 (virtiofsd: Add _llseek to the seccomp whitelist)
5/5 Checking commit cc58a0c7f1a0 (virtiofsd: Add restart_syscall to the seccomp whitelist)
=== OUTPUT END ===

Test command exited with code: 1


The full log is available at
http://patchew.org/logs/20210204183439.546918-1-dgilbert@redhat.com/testing.checkpatch/?type=message.
---
Email generated automatically by Patchew [https://patchew.org/].
Please send your feedback to patchew-devel@redhat.com

Re: [PULL 0/5] virtiofs queue: Security fix

[Dr. David Alan Gilbert]

* no-reply@patchew.org (no-reply@patchew.org) wrote:
> Patchew URL: https://patchew.org/QEMU/20210204183439.546918-1-dgilbert@redhat.com/
> 
> 
> 
> Hi,
> 
> This series seems to have some coding style problems. See output below for
> more information:
> 
> Type: series
> Message-id: 20210204183439.546918-1-dgilbert@redhat.com
> Subject: [PULL 0/5] virtiofs queue: Security fix
> 
> === TEST SCRIPT BEGIN ===
> #!/bin/bash
> git rev-parse base > /dev/null || exit 0
> git config --local diff.renamelimit 0
> git config --local diff.renames True
> git config --local diff.algorithm histogram
> ./scripts/checkpatch.pl --mailback base..
> === TEST SCRIPT END ===
> 
> Updating 3c8cf5a9c21ff8782164d1def7f44bd888713384
> From https://github.com/patchew-project/qemu
>  * [new tag]         patchew/20210204183439.546918-1-dgilbert@redhat.com -> patchew/20210204183439.546918-1-dgilbert@redhat.com
> Switched to a new branch 'test'
> cc58a0c virtiofsd: Add restart_syscall to the seccomp whitelist
> bc881ed virtiofsd: Add _llseek to the seccomp whitelist
> 449b30f virtiofsd: prevent opening of special files (CVE-2020-35517)
> 5da12fe virtiofsd: optionally return inode pointer from lo_do_lookup()
> 3690387 virtiofsd: extract lo_do_open() from lo_open()
> 
> === OUTPUT BEGIN ===
> 1/5 Checking commit 3690387a3bc2 (virtiofsd: extract lo_do_open() from lo_open())
> ERROR: return of an errno should typically be -ve (return -ENOMEM)
> #72: FILE: tools/virtiofsd/passthrough_ll.c:1674:
> +        return ENOMEM;

That's expected and OK.

> total: 1 errors, 0 warnings, 114 lines checked
> 
> Patch 1/5 has style problems, please review.  If any of these errors
> are false positives report them to the maintainer, see
> CHECKPATCH in MAINTAINERS.
> 
> 2/5 Checking commit 5da12fe61f50 (virtiofsd: optionally return inode pointer from lo_do_lookup())
> 3/5 Checking commit 449b30fcc7be (virtiofsd: prevent opening of special files (CVE-2020-35517))
> 4/5 Checking commit bc881ed54ee8 (virtiofsd: Add _llseek to the seccomp whitelist)
> 5/5 Checking commit cc58a0c7f1a0 (virtiofsd: Add restart_syscall to the seccomp whitelist)
> === OUTPUT END ===
> 
> Test command exited with code: 1
> 
> 
> The full log is available at
> http://patchew.org/logs/20210204183439.546918-1-dgilbert@redhat.com/testing.checkpatch/?type=message.
> ---
> Email generated automatically by Patchew [https://patchew.org/].
> Please send your feedback to patchew-devel@redhat.com
-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK

Re: [Virtio-fs] [PULL 0/5] virtiofs queue: Security fix

[Dr. David Alan Gilbert]

* no-reply@patchew.org (no-reply@patchew.org) wrote:
> Patchew URL: https://patchew.org/QEMU/20210204183439.546918-1-dgilbert@redhat.com/
> 
> 
> 
> Hi,
> 
> This series seems to have some coding style problems. See output below for
> more information:
> 
> Type: series
> Message-id: 20210204183439.546918-1-dgilbert@redhat.com
> Subject: [PULL 0/5] virtiofs queue: Security fix
> 
> === TEST SCRIPT BEGIN ===
> #!/bin/bash
> git rev-parse base > /dev/null || exit 0
> git config --local diff.renamelimit 0
> git config --local diff.renames True
> git config --local diff.algorithm histogram
> ./scripts/checkpatch.pl --mailback base..
> === TEST SCRIPT END ===
> 
> Updating 3c8cf5a9c21ff8782164d1def7f44bd888713384
> From https://github.com/patchew-project/qemu
>  * [new tag]         patchew/20210204183439.546918-1-dgilbert@redhat.com -> patchew/20210204183439.546918-1-dgilbert@redhat.com
> Switched to a new branch 'test'
> cc58a0c virtiofsd: Add restart_syscall to the seccomp whitelist
> bc881ed virtiofsd: Add _llseek to the seccomp whitelist
> 449b30f virtiofsd: prevent opening of special files (CVE-2020-35517)
> 5da12fe virtiofsd: optionally return inode pointer from lo_do_lookup()
> 3690387 virtiofsd: extract lo_do_open() from lo_open()
> 
> === OUTPUT BEGIN ===
> 1/5 Checking commit 3690387a3bc2 (virtiofsd: extract lo_do_open() from lo_open())
> ERROR: return of an errno should typically be -ve (return -ENOMEM)
> #72: FILE: tools/virtiofsd/passthrough_ll.c:1674:
> +        return ENOMEM;

That's expected and OK.

> total: 1 errors, 0 warnings, 114 lines checked
> 
> Patch 1/5 has style problems, please review.  If any of these errors
> are false positives report them to the maintainer, see
> CHECKPATCH in MAINTAINERS.
> 
> 2/5 Checking commit 5da12fe61f50 (virtiofsd: optionally return inode pointer from lo_do_lookup())
> 3/5 Checking commit 449b30fcc7be (virtiofsd: prevent opening of special files (CVE-2020-35517))
> 4/5 Checking commit bc881ed54ee8 (virtiofsd: Add _llseek to the seccomp whitelist)
> 5/5 Checking commit cc58a0c7f1a0 (virtiofsd: Add restart_syscall to the seccomp whitelist)
> === OUTPUT END ===
> 
> Test command exited with code: 1
> 
> 
> The full log is available at
> http://patchew.org/logs/20210204183439.546918-1-dgilbert@redhat.com/testing.checkpatch/?type=message.
> ---
> Email generated automatically by Patchew [https://patchew.org/].
> Please send your feedback to patchew-devel@redhat.com
-- 
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK

Re: [PULL 0/5] virtiofs queue: Security fix

[Peter Maydell]

On Thu, 4 Feb 2021 at 19:14, Dr. David Alan Gilbert (git)
<dgilbert@redhat.com> wrote:
>
> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
>
> The following changes since commit 1ba089f2255bfdb071be3ce6ac6c3069e8012179:
>
>   Merge remote-tracking branch 'remotes/armbru/tags/pull-qmp-2021-02-04' into staging (2021-02-04 14:15:35 +0000)
>
> are available in the Git repository at:
>
>   https://gitlab.com/dagrh/qemu.git tags/pull-virtiofs-20210204
>
> for you to fetch changes up to cf269ff8032392bbdd700e7bfd21823ad9eee3a9:
>
>   virtiofsd: Add restart_syscall to the seccomp whitelist (2021-02-04 17:50:08 +0000)
>
> ----------------------------------------------------------------
> virtiofs: Security pull 2021-02-04
>
> This contains an important CVE fix for virtiofsd,
> together with two fixes for over-eager seccomp rules.
>
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
>
> ----------------------------------------------------------------



Applied, thanks.

Please update the changelog at https://wiki.qemu.org/ChangeLog/6.0
for any user-visible changes.

-- PMM

Re: [Virtio-fs] [PULL 0/5] virtiofs queue: Security fix

[Peter Maydell]

On Thu, 4 Feb 2021 at 19:14, Dr. David Alan Gilbert (git)
<dgilbert@redhat.com> wrote:
>
> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
>
> The following changes since commit 1ba089f2255bfdb071be3ce6ac6c3069e8012179:
>
>   Merge remote-tracking branch 'remotes/armbru/tags/pull-qmp-2021-02-04' into staging (2021-02-04 14:15:35 +0000)
>
> are available in the Git repository at:
>
>   https://gitlab.com/dagrh/qemu.git tags/pull-virtiofs-20210204
>
> for you to fetch changes up to cf269ff8032392bbdd700e7bfd21823ad9eee3a9:
>
>   virtiofsd: Add restart_syscall to the seccomp whitelist (2021-02-04 17:50:08 +0000)
>
> ----------------------------------------------------------------
> virtiofs: Security pull 2021-02-04
>
> This contains an important CVE fix for virtiofsd,
> together with two fixes for over-eager seccomp rules.
>
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
>
> ----------------------------------------------------------------



Applied, thanks.

Please update the changelog at https://wiki.qemu.org/ChangeLog/6.0
for any user-visible changes.

-- PMM