posix: disable open/read/write on special files

In the file system, the responsibility w.r.to the block and char device
files is related to only support for 'creating' them (using mknod(2)).

Once the device files are created, the read/write syscalls for the specific
devices are handled by the device driver registered for the specific major
number, and depending on the minor number, it knows where to read from.
Hence, we are at risk of reading contents from devices which are handled
by the host kernel on server nodes.

By disabling open/read/write on the device file, we would be safe with
the bypass one can achieve from client side (using gfapi)

Fixes: bz#1625096

Change-Id: I48c776b0af1cbd2a5240862826d3d8918601e47f
Signed-off-by: Amar Tumballi <amarts@redhat.com>

1 files changed, 33 insertions, 0 deletions

diff --git a/xlators/storage/posix/src/posix-inode-fd-ops.c b/xlators/storage/posix/src/posix-inode-fd-ops.c
index 3552cea7f22..bc58fbfb87b 100644
--- a/xlators/storage/posix/src/posix-inode-fd-ops.c
+++ b/xlators/storage/posix/src/posix-inode-fd-ops.c
@@ -1392,6 +1392,17 @@ posix_open (call_frame_t *frame, xlator_t *this,
         priv = this->private;
         VALIDATE_OR_GOTO (priv, out);
 
+        if (loc->inode &&
+            ((loc->inode->ia_type == IA_IFBLK) ||
+             (loc->inode->ia_type == IA_IFCHR))) {
+                gf_msg (this->name, GF_LOG_ERROR, EINVAL,
+                        P_MSG_INVALID_ARGUMENT,
+                        "open received on a block/char file (%s)",
+                        uuid_utoa (loc->inode->gfid));
+                op_errno = EINVAL;
+                goto out;
+        }
+
         if (flags & O_CREAT)
                 DISK_SPACE_CHECK_AND_GOTO (frame, priv, xdata, op_ret, op_errno, out);
 
@@ -1488,6 +1499,17 @@ posix_readv (call_frame_t *frame, xlator_t *this,
         priv = this->private;
         VALIDATE_OR_GOTO (priv, out);
 
+        if (fd->inode &&
+            ((fd->inode->ia_type == IA_IFBLK) ||
+             (fd->inode->ia_type == IA_IFCHR))) {
+                gf_msg (this->name, GF_LOG_ERROR, EINVAL,
+                        P_MSG_INVALID_ARGUMENT,
+                        "readv received on a block/char file (%s)",
+                        uuid_utoa (fd->inode->gfid));
+                op_errno = EINVAL;
+                goto out;
+        }
+
         ret = posix_fd_ctx_get (fd, this, &pfd, &op_errno);
         if (ret < 0) {
                 gf_msg (this->name, GF_LOG_WARNING, op_errno, P_MSG_PFD_NULL,
@@ -1757,6 +1779,17 @@ posix_writev (call_frame_t *frame, xlator_t *this, fd_t *fd,
         VALIDATE_OR_GOTO (priv, out);
         DISK_SPACE_CHECK_AND_GOTO (frame, priv, xdata, op_ret, op_errno, out);
 
+        if (fd->inode &&
+            ((fd->inode->ia_type == IA_IFBLK) ||
+             (fd->inode->ia_type == IA_IFCHR))) {
+                gf_msg (this->name, GF_LOG_ERROR, EINVAL,
+                        P_MSG_INVALID_ARGUMENT,
+                        "writev received on a block/char file (%s)",
+                        uuid_utoa (fd->inode->gfid));
+                op_errno = EINVAL;
+                goto out;
+        }
+
         ret = posix_fd_ctx_get (fd, this, &pfd, &op_errno);
         if (ret < 0) {
                 gf_msg (this->name, GF_LOG_WARNING, ret, P_MSG_PFD_NULL,