kvm tools: use accessor function for virtio-9p FIDs

Since the 9p functions don't know the size of the fid array, they might
request an FID outside of the allowed range. Use an accessor to prevent
that and to hide the internal implementation from them.

Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>

diff --git a/tools/kvm/virtio/9p.c b/tools/kvm/virtio/9p.c
index e054dff7e9e19255b918d0dbbb39fcbfc906fe2a..3ef1a5f38b9bd6af1599ffbc8446e8f64c389a09 100644 (file)
--- a/tools/kvm/virtio/9p.c
+++ b/tools/kvm/virtio/9p.c
@@ -22,6 +22,14 @@
 static LIST_HEAD(devs);
 static int compat_id = -1;
 
+static struct p9_fid *get_fid(struct p9_dev *p9dev, int fid)
+{
+       if (fid >= VIRTIO_9P_MAX_FID)
+               die("virtio-9p max FID (%u) reached!", VIRTIO_9P_MAX_FID);
+
+       return &p9dev->fids[fid];
+}
+
 /* Warning: Immediately use value returned from this function */
 static const char *rel_to_abs(struct p9_dev *p9dev,
                              const char *path, char *abs_path)
@@ -156,7 +164,7 @@ static void virtio_p9_open(struct p9_dev *p9dev,
 
 
        virtio_p9_pdu_readf(pdu, "dd", &fid, &flags);
-       new_fid = &p9dev->fids[fid];
+       new_fid = get_fid(p9dev, fid);
 
        if (lstat(new_fid->abs_path, &st) < 0)
                goto err_out;
@@ -197,7 +205,7 @@ static void virtio_p9_create(struct p9_dev *p9dev,
 
        virtio_p9_pdu_readf(pdu, "dsddd", &dfid_val,
                            &name, &flags, &mode, &gid);
-       dfid = &p9dev->fids[dfid_val];
+       dfid = get_fid(p9dev, dfid_val);
 
        flags = virtio_p9_openflags(flags);
 
@@ -245,7 +253,7 @@ static void virtio_p9_mkdir(struct p9_dev *p9dev,
 
        virtio_p9_pdu_readf(pdu, "dsdd", &dfid_val,
                            &name, &mode, &gid);
-       dfid = &p9dev->fids[dfid_val];
+       dfid = get_fid(p9dev, dfid_val);
 
        sprintf(full_path, "%s/%s", dfid->abs_path, name);
        ret = mkdir(full_path, mode);
@@ -287,11 +295,11 @@ static void virtio_p9_walk(struct p9_dev *p9dev,
 
 
        virtio_p9_pdu_readf(pdu, "ddw", &fid_val, &newfid_val, &nwname);
-       new_fid = &p9dev->fids[newfid_val];
+       new_fid = get_fid(p9dev, newfid_val);
 
        nwqid = 0;
        if (nwname) {
-               struct p9_fid *fid = &p9dev->fids[fid_val];
+               struct p9_fid *fid = get_fid(p9dev, fid_val);
 
                strcpy(new_fid->path, fid->path);
                /* skip the space for count */
@@ -366,7 +374,7 @@ static void virtio_p9_attach(struct p9_dev *p9dev,
 
        stat2qid(&st, &qid);
 
-       fid = &p9dev->fids[fid_val];
+       fid = get_fid(p9dev, fid_val);
        fid->fid = fid_val;
        fid->uid = uid;
        fid->is_dir = 1;
@@ -418,7 +426,7 @@ static void virtio_p9_read(struct p9_dev *p9dev,
 
        rcount = 0;
        virtio_p9_pdu_readf(pdu, "dqd", &fid_val, &offset, &count);
-       fid = &p9dev->fids[fid_val];
+       fid = get_fid(p9dev, fid_val);
 
        iov_base = pdu->in_iov[0].iov_base;
        iov_len  = pdu->in_iov[0].iov_len;
@@ -469,7 +477,7 @@ static void virtio_p9_readdir(struct p9_dev *p9dev,
 
        rcount = 0;
        virtio_p9_pdu_readf(pdu, "dqd", &fid_val, &offset, &count);
-       fid = &p9dev->fids[fid_val];
+       fid = get_fid(p9dev, fid_val);
 
        if (!fid->is_dir) {
                errno = -EINVAL;
@@ -525,7 +533,7 @@ static void virtio_p9_getattr(struct p9_dev *p9dev,
        struct p9_stat_dotl statl;
 
        virtio_p9_pdu_readf(pdu, "dq", &fid_val, &request_mask);
-       fid = &p9dev->fids[fid_val];
+       fid = get_fid(p9dev, fid_val);
        if (lstat(fid->abs_path, &st) < 0)
                goto err_out;
 
@@ -573,7 +581,7 @@ static void virtio_p9_setattr(struct p9_dev *p9dev,
        struct p9_iattr_dotl p9attr;
 
        virtio_p9_pdu_readf(pdu, "dI", &fid_val, &p9attr);
-       fid = &p9dev->fids[fid_val];
+       fid = get_fid(p9dev, fid_val);
 
        if (p9attr.valid & ATTR_MODE) {
                ret = chmod(fid->abs_path, p9attr.mode);
@@ -652,7 +660,7 @@ static void virtio_p9_write(struct p9_dev *p9dev,
        int twrite_size = sizeof(u32) + sizeof(u64) + sizeof(u32);
 
        virtio_p9_pdu_readf(pdu, "dqd", &fid_val, &offset, &count);
-       fid = &p9dev->fids[fid_val];
+       fid = get_fid(p9dev, fid_val);
 
        iov_base = pdu->out_iov[0].iov_base;
        iov_len  = pdu->out_iov[0].iov_len;
@@ -691,7 +699,7 @@ static void virtio_p9_remove(struct p9_dev *p9dev,
        struct p9_fid *fid;
 
        virtio_p9_pdu_readf(pdu, "d", &fid_val);
-       fid = &p9dev->fids[fid_val];
+       fid = get_fid(p9dev, fid_val);
 
        ret = remove(fid->abs_path);
        if (ret < 0)
@@ -714,8 +722,8 @@ static void virtio_p9_rename(struct p9_dev *p9dev,
        char full_path[PATH_MAX], *new_name;
 
        virtio_p9_pdu_readf(pdu, "dds", &fid_val, &new_fid_val, &new_name);
-       fid = &p9dev->fids[fid_val];
-       new_fid = &p9dev->fids[new_fid_val];
+       fid = get_fid(p9dev, fid_val);
+       new_fid = get_fid(p9dev, new_fid_val);
 
        sprintf(full_path, "%s/%s", new_fid->abs_path, new_name);
        ret = rename(fid->abs_path, full_path);
@@ -740,7 +748,7 @@ static void virtio_p9_readlink(struct p9_dev *p9dev,
        char target_path[PATH_MAX];
 
        virtio_p9_pdu_readf(pdu, "d", &fid_val);
-       fid = &p9dev->fids[fid_val];
+       fid = get_fid(p9dev, fid_val);
 
        memset(target_path, 0, PATH_MAX);
        ret = readlink(fid->abs_path, target_path, PATH_MAX - 1);
@@ -766,7 +774,7 @@ static void virtio_p9_statfs(struct p9_dev *p9dev,
        struct statfs stat_buf;
 
        virtio_p9_pdu_readf(pdu, "d", &fid_val);
-       fid = &p9dev->fids[fid_val];
+       fid = get_fid(p9dev, fid_val);
 
        ret = statfs(fid->abs_path, &stat_buf);
        if (ret < 0)
@@ -801,7 +809,7 @@ static void virtio_p9_mknod(struct p9_dev *p9dev,
        virtio_p9_pdu_readf(pdu, "dsdddd", &fid_val, &name, &mode,
                            &major, &minor, &gid);
 
-       dfid = &p9dev->fids[fid_val];
+       dfid = get_fid(p9dev, fid_val);
        sprintf(full_path, "%s/%s", dfid->abs_path, name);
        ret = mknod(full_path, mode, makedev(major, minor));
        if (ret < 0)
@@ -838,7 +846,7 @@ static void virtio_p9_fsync(struct p9_dev *p9dev,
        u32 fid_val, datasync;
 
        virtio_p9_pdu_readf(pdu, "dd", &fid_val, &datasync);
-       fid = &p9dev->fids[fid_val];
+       fid = get_fid(p9dev, fid_val);
 
        if (datasync)
                ret = fdatasync(fid->fd);
@@ -867,7 +875,7 @@ static void virtio_p9_symlink(struct p9_dev *p9dev,
 
        virtio_p9_pdu_readf(pdu, "dssd", &fid_val, &name, &old_path, &gid);
 
-       dfid = &p9dev->fids[fid_val];
+       dfid = get_fid(p9dev, fid_val);
        sprintf(new_name, "%s/%s", dfid->abs_path, name);
        ret = symlink(old_path, new_name);
        if (ret < 0)
@@ -905,8 +913,8 @@ static void virtio_p9_link(struct p9_dev *p9dev,
 
        virtio_p9_pdu_readf(pdu, "dds", &dfid_val, &fid_val, &name);
 
-       dfid = &p9dev->fids[dfid_val];
-       fid =  &p9dev->fids[fid_val];
+       dfid = get_fid(p9dev, dfid_val);
+       fid =  get_fid(p9dev, fid_val);
        sprintf(full_path, "%s/%s", dfid->abs_path, name);
        ret = link(fid->abs_path, full_path);
        if (ret < 0)
@@ -1006,8 +1014,8 @@ static void virtio_p9_renameat(struct p9_dev *p9dev,
        virtio_p9_pdu_readf(pdu, "dsds", &old_dfid_val, &old_name,
                            &new_dfid_val, &new_name);
 
-       old_dfid = &p9dev->fids[old_dfid_val];
-       new_dfid = &p9dev->fids[new_dfid_val];
+       old_dfid = get_fid(p9dev, old_dfid_val);
+       new_dfid = get_fid(p9dev, new_dfid_val);
 
        sprintf(old_full_path, "%s/%s", old_dfid->abs_path, old_name);
        sprintf(new_full_path, "%s/%s", new_dfid->abs_path, new_name);
@@ -1019,9 +1027,9 @@ static void virtio_p9_renameat(struct p9_dev *p9dev,
         * that.
         */
        for (i = 0; i < VIRTIO_9P_MAX_FID; i++) {
-               if (p9dev->fids[i].fid != P9_NOFID &&
-                   virtio_p9_ancestor(p9dev->fids[i].path, old_name)) {
-                       virtio_p9_fix_path(p9dev->fids[i].path, old_name,
+               if (get_fid(p9dev, i)->fid != P9_NOFID &&
+                   virtio_p9_ancestor(get_fid(p9dev, i)->path, old_name)) {
+                       virtio_p9_fix_path(get_fid(p9dev, i)->path, old_name,
                                           new_name);
                }
        }
@@ -1047,7 +1055,7 @@ static void virtio_p9_unlinkat(struct p9_dev *p9dev,
        char full_path[PATH_MAX];
 
        virtio_p9_pdu_readf(pdu, "dsd", &fid_val, &name, &flags);
-       fid = &p9dev->fids[fid_val];
+       fid = get_fid(p9dev, fid_val);
 
        sprintf(full_path, "%s/%s", fid->abs_path, name);
        ret = remove(full_path);
@@ -1293,8 +1301,8 @@ int virtio_9p__register(struct kvm *kvm, const char *root, const char *tag_name)
         * absolute path of an fid without playing with strings.
         */
        for (i = 0; i < VIRTIO_9P_MAX_FID; i++) {
-               strcpy(p9dev->fids[i].abs_path, root);
-               p9dev->fids[i].path = p9dev->fids[i].abs_path + root_len;
+               strcpy(get_fid(p9dev, i)->abs_path, root);
+               get_fid(p9dev, i)->path = get_fid(p9dev, i)->abs_path + root_len;
        }
        p9dev->config->tag_len = strlen(tag_name);
        if (p9dev->config->tag_len > MAX_TAG_LEN) {