From: Stefan Hajnoczi <stefanha@redhat.com>

Date: Mon, 27 Jan 2020 19:01:14 +0000

Subject: [PATCH] virtiofsd: passthrough_ll: add ino_map to hide lo_inode

 pointers

Do not expose lo_inode pointers to clients.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

Reviewed-by: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>

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

(cherry picked from commit 92fb57b83cdbfc4bf53c0c46a3d0bcbc36e64126)

---

 tools/virtiofsd/passthrough_ll.c | 144 ++++++++++++++++++++++++-------

 1 file changed, 114 insertions(+), 30 deletions(-)

diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c

index e83a976587..a3ebf74eab 100644

--- a/tools/virtiofsd/passthrough_ll.c

+++ b/tools/virtiofsd/passthrough_ll.c

@@ -57,8 +57,8 @@

 #include "passthrough_helpers.h"

 /*

- * We are re-using pointers to our `struct lo_inode` and `struct

- * lo_dirp` elements as inodes. This means that we must be able to

+ * We are re-using pointers to our `struct lo_inode`

+ * elements as inodes. This means that we must be able to

  * store uintptr_t values in a fuse_ino_t variable. The following

  * incantation checks this condition at compile time.

  */

@@ -76,7 +76,7 @@ struct _uintptr_to_must_hold_fuse_ino_t_dummy_struct {

 struct lo_map_elem {

     union {

-        /* Element values will go here... */

+        struct lo_inode *inode;

         ssize_t freelist;

     };

     bool in_use;

@@ -97,6 +97,7 @@ struct lo_inode {

     ino_t ino;

     dev_t dev;

     uint64_t refcount; /* protected by lo->mutex */

+    fuse_ino_t fuse_ino;

 };

 struct lo_cred {

@@ -121,6 +122,7 @@ struct lo_data {

     int cache;

     int timeout_set;

     struct lo_inode root; /* protected by lo->mutex */

+    struct lo_map ino_map; /* protected by lo->mutex */

 };

 static const struct fuse_opt lo_opts[] = {

@@ -145,14 +147,14 @@ static struct lo_data *lo_data(fuse_req_t req)

     return (struct lo_data *)fuse_req_userdata(req);

 }

-__attribute__((unused)) static void lo_map_init(struct lo_map *map)

+static void lo_map_init(struct lo_map *map)

 {

     map->elems = NULL;

     map->nelems = 0;

     map->freelist = -1;

 }

-__attribute__((unused)) static void lo_map_destroy(struct lo_map *map)

+static void lo_map_destroy(struct lo_map *map)

 {

     free(map->elems);

 }

@@ -183,8 +185,7 @@ static int lo_map_grow(struct lo_map *map, size_t new_nelems)

     return 1;

 }

-__attribute__((unused)) static struct lo_map_elem *

-lo_map_alloc_elem(struct lo_map *map)

+static struct lo_map_elem *lo_map_alloc_elem(struct lo_map *map)

 {

     struct lo_map_elem *elem;

@@ -200,8 +201,7 @@ lo_map_alloc_elem(struct lo_map *map)

     return elem;

 }

-__attribute__((unused)) static struct lo_map_elem *

-lo_map_reserve(struct lo_map *map, size_t key)

+static struct lo_map_elem *lo_map_reserve(struct lo_map *map, size_t key)

 {

     ssize_t *prev;

@@ -222,8 +222,7 @@ lo_map_reserve(struct lo_map *map, size_t key)

     return NULL;

 }

-__attribute__((unused)) static struct lo_map_elem *

-lo_map_get(struct lo_map *map, size_t key)

+static struct lo_map_elem *lo_map_get(struct lo_map *map, size_t key)

 {

     if (key >= map->nelems) {

         return NULL;

@@ -234,8 +233,7 @@ lo_map_get(struct lo_map *map, size_t key)

     return &map->elems[key];

 }

-__attribute__((unused)) static void lo_map_remove(struct lo_map *map,

-                                                  size_t key)

+static void lo_map_remove(struct lo_map *map, size_t key)

 {

     struct lo_map_elem *elem;

@@ -254,18 +252,40 @@ __attribute__((unused)) static void lo_map_remove(struct lo_map *map,

     map->freelist = key;

 }

+/* Assumes lo->mutex is held */

+static ssize_t lo_add_inode_mapping(fuse_req_t req, struct lo_inode *inode)

+{

+    struct lo_map_elem *elem;

+

+    elem = lo_map_alloc_elem(&lo_data(req)->ino_map);

+    if (!elem) {

+        return -1;

+    }

+

+    elem->inode = inode;

+    return elem - lo_data(req)->ino_map.elems;

+}

+

 static struct lo_inode *lo_inode(fuse_req_t req, fuse_ino_t ino)

 {

-    if (ino == FUSE_ROOT_ID) {

-        return &lo_data(req)->root;

-    } else {

-        return (struct lo_inode *)(uintptr_t)ino;

+    struct lo_data *lo = lo_data(req);

+    struct lo_map_elem *elem;

+

+    pthread_mutex_lock(&lo->mutex);

+    elem = lo_map_get(&lo->ino_map, ino);

+    pthread_mutex_unlock(&lo->mutex);

+

+    if (!elem) {

+        return NULL;

     }

+

+    return elem->inode;

 }

 static int lo_fd(fuse_req_t req, fuse_ino_t ino)

 {

-    return lo_inode(req, ino)->fd;

+    struct lo_inode *inode = lo_inode(req, ino);

+    return inode ? inode->fd : -1;

 }

 static bool lo_debug(fuse_req_t req)

@@ -337,10 +357,18 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr,

 {

     int saverr;

     char procname[64];

-    struct lo_inode *inode = lo_inode(req, ino);

-    int ifd = inode->fd;

+    struct lo_inode *inode;

+    int ifd;

     int res;

+    inode = lo_inode(req, ino);

+    if (!inode) {

+        fuse_reply_err(req, EBADF);

+        return;

+    }

+

+    ifd = inode->fd;

+

     if (valid & FUSE_SET_ATTR_MODE) {

         if (fi) {

             res = fchmod(fi->fh, attr->st_mode);

@@ -470,6 +498,7 @@ static int lo_do_lookup(fuse_req_t req, fuse_ino_t parent, const char *name,

         inode->dev = e->attr.st_dev;

         pthread_mutex_lock(&lo->mutex);

+        inode->fuse_ino = lo_add_inode_mapping(req, inode);

         prev = &lo->root;

         next = prev->next;

         next->prev = inode;

@@ -478,7 +507,7 @@ static int lo_do_lookup(fuse_req_t req, fuse_ino_t parent, const char *name,

         prev->next = inode;

         pthread_mutex_unlock(&lo->mutex);

     }

-    e->ino = (uintptr_t)inode;

+    e->ino = inode->fuse_ino;

     if (lo_debug(req)) {

         fuse_log(FUSE_LOG_DEBUG, "  %lli/%s -> %lli\n",

@@ -582,10 +611,16 @@ static void lo_mknod_symlink(fuse_req_t req, fuse_ino_t parent,

 {

     int res;

     int saverr;

-    struct lo_inode *dir = lo_inode(req, parent);

+    struct lo_inode *dir;

     struct fuse_entry_param e;

     struct lo_cred old = {};

+    dir = lo_inode(req, parent);

+    if (!dir) {

+        fuse_reply_err(req, EBADF);

+        return;

+    }

+

     saverr = ENOMEM;

     saverr = lo_change_cred(req, &old;;

@@ -663,10 +698,16 @@ static void lo_link(fuse_req_t req, fuse_ino_t ino, fuse_ino_t parent,

 {

     int res;

     struct lo_data *lo = lo_data(req);

-    struct lo_inode *inode = lo_inode(req, ino);

+    struct lo_inode *inode;

     struct fuse_entry_param e;

     int saverr;

+    inode = lo_inode(req, ino);

+    if (!inode) {

+        fuse_reply_err(req, EBADF);

+        return;

+    }

+

     memset(&e, 0, sizeof(struct fuse_entry_param));

     e.attr_timeout = lo->timeout;

     e.entry_timeout = lo->timeout;

@@ -684,7 +725,7 @@ static void lo_link(fuse_req_t req, fuse_ino_t ino, fuse_ino_t parent,

     pthread_mutex_lock(&lo->mutex);

     inode->refcount++;

     pthread_mutex_unlock(&lo->mutex);

-    e.ino = (uintptr_t)inode;

+    e.ino = inode->fuse_ino;

     if (lo_debug(req)) {

         fuse_log(FUSE_LOG_DEBUG, "  %lli/%s -> %lli\n",

@@ -750,10 +791,10 @@ static void unref_inode(struct lo_data *lo, struct lo_inode *inode, uint64_t n)

         next->prev = prev;

         prev->next = next;

+        lo_map_remove(&lo->ino_map, inode->fuse_ino);

         pthread_mutex_unlock(&lo->mutex);

         close(inode->fd);

         free(inode);

-

     } else {

         pthread_mutex_unlock(&lo->mutex);

     }

@@ -762,7 +803,12 @@ static void unref_inode(struct lo_data *lo, struct lo_inode *inode, uint64_t n)

 static void lo_forget_one(fuse_req_t req, fuse_ino_t ino, uint64_t nlookup)

 {

     struct lo_data *lo = lo_data(req);

-    struct lo_inode *inode = lo_inode(req, ino);

+    struct lo_inode *inode;

+

+    inode = lo_inode(req, ino);

+    if (!inode) {

+        return;

+    }

     if (lo_debug(req)) {

         fuse_log(FUSE_LOG_DEBUG, "  forget %lli %lli -%lli\n",

@@ -1244,10 +1290,16 @@ static void lo_getxattr(fuse_req_t req, fuse_ino_t ino, const char *name,

 {

     char *value = NULL;

     char procname[64];

-    struct lo_inode *inode = lo_inode(req, ino);

+    struct lo_inode *inode;

     ssize_t ret;

     int saverr;

+    inode = lo_inode(req, ino);

+    if (!inode) {

+        fuse_reply_err(req, EBADF);

+        return;

+    }

+

     saverr = ENOSYS;

     if (!lo_data(req)->xattr) {

         goto out;

@@ -1306,10 +1358,16 @@ static void lo_listxattr(fuse_req_t req, fuse_ino_t ino, size_t size)

 {

     char *value = NULL;

     char procname[64];

-    struct lo_inode *inode = lo_inode(req, ino);

+    struct lo_inode *inode;

     ssize_t ret;

     int saverr;

+    inode = lo_inode(req, ino);

+    if (!inode) {

+        fuse_reply_err(req, EBADF);

+        return;

+    }

+

     saverr = ENOSYS;

     if (!lo_data(req)->xattr) {

         goto out;

@@ -1367,10 +1425,16 @@ static void lo_setxattr(fuse_req_t req, fuse_ino_t ino, const char *name,

                         const char *value, size_t size, int flags)

 {

     char procname[64];

-    struct lo_inode *inode = lo_inode(req, ino);

+    struct lo_inode *inode;

     ssize_t ret;

     int saverr;

+    inode = lo_inode(req, ino);

+    if (!inode) {

+        fuse_reply_err(req, EBADF);

+        return;

+    }

+

     saverr = ENOSYS;

     if (!lo_data(req)->xattr) {

         goto out;

@@ -1400,10 +1464,16 @@ out:

 static void lo_removexattr(fuse_req_t req, fuse_ino_t ino, const char *name)

 {

     char procname[64];

-    struct lo_inode *inode = lo_inode(req, ino);

+    struct lo_inode *inode;

     ssize_t ret;

     int saverr;

+    inode = lo_inode(req, ino);

+    if (!inode) {

+        fuse_reply_err(req, EBADF);

+        return;

+    }

+

     saverr = ENOSYS;

     if (!lo_data(req)->xattr) {

         goto out;

@@ -1522,6 +1592,7 @@ int main(int argc, char *argv[])

     struct fuse_session *se;

     struct fuse_cmdline_opts opts;

     struct lo_data lo = { .debug = 0, .writeback = 0 };

+    struct lo_map_elem *root_elem;

     int ret = -1;

     /* Don't mask creation mode, kernel already did that */

@@ -1530,8 +1601,19 @@ int main(int argc, char *argv[])

     pthread_mutex_init(&lo.mutex, NULL);

     lo.root.next = lo.root.prev = &lo.root;

     lo.root.fd = -1;

+    lo.root.fuse_ino = FUSE_ROOT_ID;

     lo.cache = CACHE_NORMAL;

+    /*

+     * Set up the ino map like this:

+     * [0] Reserved (will not be used)

+     * [1] Root inode

+     */

+    lo_map_init(&lo.ino_map);

+    lo_map_reserve(&lo.ino_map, 0)->in_use = false;

+    root_elem = lo_map_reserve(&lo.ino_map, lo.root.fuse_ino);

+    root_elem->inode = &lo.root;

+

     if (fuse_parse_cmdline(&args, &opts) != 0) {

         return 1;

     }

@@ -1628,6 +1710,8 @@ err_out2:

 err_out1:

     fuse_opt_free_args(&args);

+    lo_map_destroy(&lo.ino_map);

+

     if (lo.root.fd >= 0) {

         close(lo.root.fd);

     }