Commit 3b5ee9e8 authored by Antonios Motakis's avatar Antonios Motakis Committed by Greg Kurz
Browse files

9p: Treat multiple devices on one export as an error 



The QID path should uniquely identify a file. However, the
inode of a file is currently used as the QID path, which
on its own only uniquely identifies files within a device.
Here we track the device hosting the 9pfs share, in order
to prevent security issues with QID path collisions from
other devices.

We only print a warning for now but a subsequent patch will
allow users to have finer control over the desired behaviour.
Failing the I/O will be one the proposed behaviour, so we
also change stat_to_qid() to return an error here in order to
keep other patches simpler.

Signed-off-by: default avatarAntonios Motakis <antonios.motakis@huawei.com>
[CS: - Assign dev_id to export root's device already in
       v9fs_device_realize_common(), not postponed in
       stat_to_qid().
     - error_report_once() if more than one device was
       shared by export.
     - Return -ENODEV instead of -ENOSYS in stat_to_qid().
     - Fixed typo in log comment. ]
Signed-off-by: default avatarChristian Schoenebeck <qemu_oss@crudebyte.com>
[groug, changed to warning, updated message and changelog]
Signed-off-by: default avatarGreg Kurz <groug@kaod.org>
parent ea52cdd4

hw/9pfs/9p.c

+56 −14
Original line number Diff line number Diff line
@@ -573,10 +573,19 @@ static void coroutine_fn virtfs_reset(V9fsPDU *pdu) 
                                P9_STAT_MODE_SOCKET)



/* This is the algorithm from ufs in spfs */

static void stat_to_qid(const struct stat *stbuf, V9fsQID *qidp)

static int stat_to_qid(V9fsPDU *pdu, const struct stat *stbuf, V9fsQID *qidp)

{

    size_t size;



    if (pdu->s->dev_id != stbuf->st_dev) {

        warn_report_once(

            "9p: Multiple devices detected in same VirtFS export, "

            "which might lead to file ID collisions and severe "

            "misbehaviours on guest! You should use a separate "

            "export for each device shared from host."

        );

    }



    memset(&qidp->path, 0, sizeof(qidp->path));

    size = MIN(sizeof(stbuf->st_ino), sizeof(qidp->path));

    memcpy(&qidp->path, &stbuf->st_ino, size);
@@ -588,6 +597,8 @@ static void stat_to_qid(const struct stat *stbuf, V9fsQID *qidp) 
    if (S_ISLNK(stbuf->st_mode)) {

        qidp->type |= P9_QID_TYPE_SYMLINK;

    }



    return 0;

}



static int coroutine_fn fid_to_qid(V9fsPDU *pdu, V9fsFidState *fidp,
@@ -600,7 +611,10 @@ static int coroutine_fn fid_to_qid(V9fsPDU *pdu, V9fsFidState *fidp, 
    if (err < 0) {

        return err;

    }

    stat_to_qid(&stbuf, qidp);

    err = stat_to_qid(pdu, &stbuf, qidp);

    if (err < 0) {

        return err;

    }

    return 0;

}
@@ -831,7 +845,10 @@ static int coroutine_fn stat_to_v9stat(V9fsPDU *pdu, V9fsPath *path, 


    memset(v9stat, 0, sizeof(*v9stat));



    stat_to_qid(stbuf, &v9stat->qid);

    err = stat_to_qid(pdu, stbuf, &v9stat->qid);

    if (err < 0) {

        return err;

    }

    v9stat->mode = stat_to_v9mode(stbuf);

    v9stat->atime = stbuf->st_atime;

    v9stat->mtime = stbuf->st_mtime;
@@ -892,7 +909,7 @@ static int coroutine_fn stat_to_v9stat(V9fsPDU *pdu, V9fsPath *path, 
#define P9_STATS_ALL           0x00003fffULL /* Mask for All fields above */





static void stat_to_v9stat_dotl(V9fsState *s, const struct stat *stbuf,

static int stat_to_v9stat_dotl(V9fsPDU *pdu, const struct stat *stbuf,

                                V9fsStatDotl *v9lstat)

{

    memset(v9lstat, 0, sizeof(*v9lstat));
@@ -914,7 +931,7 @@ static void stat_to_v9stat_dotl(V9fsState *s, const struct stat *stbuf, 
    /* Currently we only support BASIC fields in stat */

    v9lstat->st_result_mask = P9_STATS_BASIC;



    stat_to_qid(stbuf, &v9lstat->qid);

    return stat_to_qid(pdu, stbuf, &v9lstat->qid);

}



static void print_sg(struct iovec *sg, int cnt)
@@ -1116,7 +1133,6 @@ static void coroutine_fn v9fs_getattr(void *opaque) 
    uint64_t request_mask;

    V9fsStatDotl v9stat_dotl;

    V9fsPDU *pdu = opaque;

    V9fsState *s = pdu->s;



    retval = pdu_unmarshal(pdu, offset, "dq", &fid, &request_mask);

    if (retval < 0) {
@@ -1137,7 +1153,10 @@ static void coroutine_fn v9fs_getattr(void *opaque) 
    if (retval < 0) {

        goto out;

    }

    stat_to_v9stat_dotl(s, &stbuf, &v9stat_dotl);

    retval = stat_to_v9stat_dotl(pdu, &stbuf, &v9stat_dotl);

    if (retval < 0) {

        goto out;

    }



    /*  fill st_gen if requested and supported by underlying fs */

    if (request_mask & P9_STATS_GEN) {
@@ -1382,7 +1401,10 @@ static void coroutine_fn v9fs_walk(void *opaque) 
            if (err < 0) {

                goto out;

            }

            stat_to_qid(&stbuf, &qid);

            err = stat_to_qid(pdu, &stbuf, &qid);

            if (err < 0) {

                goto out;

            }

            v9fs_path_copy(&dpath, &path);

        }

        memcpy(&qids[name_idx], &qid, sizeof(qid));
@@ -1484,7 +1506,10 @@ static void coroutine_fn v9fs_open(void *opaque) 
    if (err < 0) {

        goto out;

    }

    stat_to_qid(&stbuf, &qid);

    err = stat_to_qid(pdu, &stbuf, &qid);

    if (err < 0) {

        goto out;

    }

    if (S_ISDIR(stbuf.st_mode)) {

        err = v9fs_co_opendir(pdu, fidp);

        if (err < 0) {
@@ -1594,7 +1619,10 @@ static void coroutine_fn v9fs_lcreate(void *opaque) 
        fidp->flags |= FID_NON_RECLAIMABLE;

    }

    iounit =  get_iounit(pdu, &fidp->path);

    stat_to_qid(&stbuf, &qid);

    err = stat_to_qid(pdu, &stbuf, &qid);

    if (err < 0) {

        goto out;

    }

    err = pdu_marshal(pdu, offset, "Qd", &qid, iounit);

    if (err < 0) {

        goto out;
@@ -2328,7 +2356,10 @@ static void coroutine_fn v9fs_create(void *opaque) 
        }

    }

    iounit = get_iounit(pdu, &fidp->path);

    stat_to_qid(&stbuf, &qid);

    err = stat_to_qid(pdu, &stbuf, &qid);

    if (err < 0) {

        goto out;

    }

    err = pdu_marshal(pdu, offset, "Qd", &qid, iounit);

    if (err < 0) {

        goto out;
@@ -2385,7 +2416,10 @@ static void coroutine_fn v9fs_symlink(void *opaque) 
    if (err < 0) {

        goto out;

    }

    stat_to_qid(&stbuf, &qid);

    err = stat_to_qid(pdu, &stbuf, &qid);

    if (err < 0) {

        goto out;

    }

    err =  pdu_marshal(pdu, offset, "Q", &qid);

    if (err < 0) {

        goto out;
@@ -3065,7 +3099,10 @@ static void coroutine_fn v9fs_mknod(void *opaque) 
    if (err < 0) {

        goto out;

    }

    stat_to_qid(&stbuf, &qid);

    err = stat_to_qid(pdu, &stbuf, &qid);

    if (err < 0) {

        goto out;

    }

    err = pdu_marshal(pdu, offset, "Q", &qid);

    if (err < 0) {

        goto out;
@@ -3223,7 +3260,10 @@ static void coroutine_fn v9fs_mkdir(void *opaque) 
    if (err < 0) {

        goto out;

    }

    stat_to_qid(&stbuf, &qid);

    err = stat_to_qid(pdu, &stbuf, &qid);

    if (err < 0) {

        goto out;

    }

    err = pdu_marshal(pdu, offset, "Q", &qid);

    if (err < 0) {

        goto out;
@@ -3634,6 +3674,8 @@ int v9fs_device_realize_common(V9fsState *s, const V9fsTransport *t, 
        goto out;

    }



    s->dev_id = stat.st_dev;



    s->ctx.fst = &fse->fst;

    fsdev_throttle_init(s->ctx.fst);

hw/9pfs/9p.h

+1 −0
Original line number Diff line number Diff line
@@ -256,6 +256,7 @@ struct V9fsState 
    Error *migration_blocker;

    V9fsConf fsconf;

    V9fsQID root_qid;

    dev_t dev_id;

};



/* 9p2000.L open flags */