[Virtio-fs] [PULL 04/12] virtiofsd: Parse extended "struct fuse_init_in"

["Dr. David Alan Gilbert (git)" <dgilbert@redhat.com>]

From: Vivek Goyal <vgoyal@redhat.com>

Add some code to parse extended "struct fuse_init_in". And use a local
variable "flag" to represent 64 bit flags. This will make it easier
to add more features without having to worry about two 32bit flags (->flags
and ->flags2) in "fuse_struct_in".

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Message-Id: <20220208204813.682906-4-vgoyal@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 tools/virtiofsd/fuse_lowlevel.c | 61 +++++++++++++++++++++------------
 1 file changed, 39 insertions(+), 22 deletions(-)

diff --git a/tools/virtiofsd/fuse_lowlevel.c b/tools/virtiofsd/fuse_lowlevel.c
index ce29a70253..b6712b763a 100644
--- a/tools/virtiofsd/fuse_lowlevel.c
+++ b/tools/virtiofsd/fuse_lowlevel.c
@@ -1881,11 +1881,14 @@ static void do_init(fuse_req_t req, fuse_ino_t nodeid,
 {
     size_t compat_size = offsetof(struct fuse_init_in, max_readahead);
     size_t compat2_size = offsetof(struct fuse_init_in, flags) + sizeof(uint32_t);
+    /* Fuse structure extended with minor version 36 */
+    size_t compat3_size = endof(struct fuse_init_in, unused);
     struct fuse_init_in *arg;
     struct fuse_init_out outarg;
     struct fuse_session *se = req->se;
     size_t bufsize = se->bufsize;
     size_t outargsize = sizeof(outarg);
+    uint64_t flags = 0;
 
     (void)nodeid;
 
@@ -1902,11 +1905,25 @@ static void do_init(fuse_req_t req, fuse_ino_t nodeid,
             fuse_reply_err(req, EINVAL);
             return;
         }
+        flags |= arg->flags;
+    }
+
+    /*
+     * fuse_init_in was extended again with minor version 36. Just read
+     * current known size of fuse_init so that future extension and
+     * header rebase does not cause breakage.
+     */
+    if (sizeof(*arg) > compat2_size && (arg->flags & FUSE_INIT_EXT)) {
+        if (!fuse_mbuf_iter_advance(iter, compat3_size - compat2_size)) {
+            fuse_reply_err(req, EINVAL);
+            return;
+        }
+        flags |= (uint64_t) arg->flags2 << 32;
     }
 
     fuse_log(FUSE_LOG_DEBUG, "INIT: %u.%u\n", arg->major, arg->minor);
     if (arg->major == 7 && arg->minor >= 6) {
-        fuse_log(FUSE_LOG_DEBUG, "flags=0x%08x\n", arg->flags);
+        fuse_log(FUSE_LOG_DEBUG, "flags=0x%016llx\n", flags);
         fuse_log(FUSE_LOG_DEBUG, "max_readahead=0x%08x\n", arg->max_readahead);
     }
     se->conn.proto_major = arg->major;
@@ -1934,68 +1951,68 @@ static void do_init(fuse_req_t req, fuse_ino_t nodeid,
     if (arg->max_readahead < se->conn.max_readahead) {
         se->conn.max_readahead = arg->max_readahead;
     }
-    if (arg->flags & FUSE_ASYNC_READ) {
+    if (flags & FUSE_ASYNC_READ) {
         se->conn.capable |= FUSE_CAP_ASYNC_READ;
     }
-    if (arg->flags & FUSE_POSIX_LOCKS) {
+    if (flags & FUSE_POSIX_LOCKS) {
         se->conn.capable |= FUSE_CAP_POSIX_LOCKS;
     }
-    if (arg->flags & FUSE_ATOMIC_O_TRUNC) {
+    if (flags & FUSE_ATOMIC_O_TRUNC) {
         se->conn.capable |= FUSE_CAP_ATOMIC_O_TRUNC;
     }
-    if (arg->flags & FUSE_EXPORT_SUPPORT) {
+    if (flags & FUSE_EXPORT_SUPPORT) {
         se->conn.capable |= FUSE_CAP_EXPORT_SUPPORT;
     }
-    if (arg->flags & FUSE_DONT_MASK) {
+    if (flags & FUSE_DONT_MASK) {
         se->conn.capable |= FUSE_CAP_DONT_MASK;
     }
-    if (arg->flags & FUSE_FLOCK_LOCKS) {
+    if (flags & FUSE_FLOCK_LOCKS) {
         se->conn.capable |= FUSE_CAP_FLOCK_LOCKS;
     }
-    if (arg->flags & FUSE_AUTO_INVAL_DATA) {
+    if (flags & FUSE_AUTO_INVAL_DATA) {
         se->conn.capable |= FUSE_CAP_AUTO_INVAL_DATA;
     }
-    if (arg->flags & FUSE_DO_READDIRPLUS) {
+    if (flags & FUSE_DO_READDIRPLUS) {
         se->conn.capable |= FUSE_CAP_READDIRPLUS;
     }
-    if (arg->flags & FUSE_READDIRPLUS_AUTO) {
+    if (flags & FUSE_READDIRPLUS_AUTO) {
         se->conn.capable |= FUSE_CAP_READDIRPLUS_AUTO;
     }
-    if (arg->flags & FUSE_ASYNC_DIO) {
+    if (flags & FUSE_ASYNC_DIO) {
         se->conn.capable |= FUSE_CAP_ASYNC_DIO;
     }
-    if (arg->flags & FUSE_WRITEBACK_CACHE) {
+    if (flags & FUSE_WRITEBACK_CACHE) {
         se->conn.capable |= FUSE_CAP_WRITEBACK_CACHE;
     }
-    if (arg->flags & FUSE_NO_OPEN_SUPPORT) {
+    if (flags & FUSE_NO_OPEN_SUPPORT) {
         se->conn.capable |= FUSE_CAP_NO_OPEN_SUPPORT;
     }
-    if (arg->flags & FUSE_PARALLEL_DIROPS) {
+    if (flags & FUSE_PARALLEL_DIROPS) {
         se->conn.capable |= FUSE_CAP_PARALLEL_DIROPS;
     }
-    if (arg->flags & FUSE_POSIX_ACL) {
+    if (flags & FUSE_POSIX_ACL) {
         se->conn.capable |= FUSE_CAP_POSIX_ACL;
     }
-    if (arg->flags & FUSE_HANDLE_KILLPRIV) {
+    if (flags & FUSE_HANDLE_KILLPRIV) {
         se->conn.capable |= FUSE_CAP_HANDLE_KILLPRIV;
     }
-    if (arg->flags & FUSE_NO_OPENDIR_SUPPORT) {
+    if (flags & FUSE_NO_OPENDIR_SUPPORT) {
         se->conn.capable |= FUSE_CAP_NO_OPENDIR_SUPPORT;
     }
-    if (!(arg->flags & FUSE_MAX_PAGES)) {
+    if (!(flags & FUSE_MAX_PAGES)) {
         size_t max_bufsize = FUSE_DEFAULT_MAX_PAGES_PER_REQ * getpagesize() +
                              FUSE_BUFFER_HEADER_SIZE;
         if (bufsize > max_bufsize) {
             bufsize = max_bufsize;
         }
     }
-    if (arg->flags & FUSE_SUBMOUNTS) {
+    if (flags & FUSE_SUBMOUNTS) {
         se->conn.capable |= FUSE_CAP_SUBMOUNTS;
     }
-    if (arg->flags & FUSE_HANDLE_KILLPRIV_V2) {
+    if (flags & FUSE_HANDLE_KILLPRIV_V2) {
         se->conn.capable |= FUSE_CAP_HANDLE_KILLPRIV_V2;
     }
-    if (arg->flags & FUSE_SETXATTR_EXT) {
+    if (flags & FUSE_SETXATTR_EXT) {
         se->conn.capable |= FUSE_CAP_SETXATTR_EXT;
     }
 #ifdef HAVE_SPLICE
@@ -2063,7 +2080,7 @@ static void do_init(fuse_req_t req, fuse_ino_t nodeid,
     if (se->conn.max_write < bufsize - FUSE_BUFFER_HEADER_SIZE) {
         se->bufsize = se->conn.max_write + FUSE_BUFFER_HEADER_SIZE;
     }
-    if (arg->flags & FUSE_MAX_PAGES) {
+    if (flags & FUSE_MAX_PAGES) {
         outarg.flags |= FUSE_MAX_PAGES;
         outarg.max_pages = (se->conn.max_write - 1) / getpagesize() + 1;
     }
-- 
2.35.1