| Message ID | 26b626706b5fa0c492413a3279512c17952be5de.1561575449.git.qemu_oss@crudebyte.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | 9p: Fix file ID collisions | expand |
On Wed, 26 Jun 2019 20:30:41 +0200 Christian Schoenebeck via Qemu-devel <qemu-devel@nongnu.org> wrote: > 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 wiles within a device. s/wile/files > Here we track the device hosting the 9pfs share, in order > to prevent security issues with QID path collisions from > other devices. > > Signed-off-by: Antonios Motakis <antonios.motakis@huawei.com> You should mention here the changes you made to the original patch. > Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com> > --- > hw/9pfs/9p.c | 71 ++++++++++++++++++++++++++++++++++++++++++++++++------------ > hw/9pfs/9p.h | 1 + > 2 files changed, 58 insertions(+), 14 deletions(-) > > diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c > index 586a6dccba..cbaa212625 100644 > --- a/hw/9pfs/9p.c > +++ b/hw/9pfs/9p.c > @@ -572,10 +572,20 @@ 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 == 0) { > + pdu->s->dev_id = stbuf->st_dev; st_dev should be captured in v9fs_device_realize_common() since we lstat() the root there, instead of every request doing the check. > + } else if (pdu->s->dev_id != stbuf->st_dev) { > + error_report_once( > + "9p: Multiple devices detected in same VirtFS export. " > + "You must use a separate export for each device." > + ); > + return -ENOSYS; This error is likely to end up as the return value of a syscall in the guest and -ENOSYS usually means the syscall isn't implemented, which is obviously not the case. Maybe return -EPERM instead ? > + } > + > memset(&qidp->path, 0, sizeof(qidp->path)); > size = MIN(sizeof(stbuf->st_ino), sizeof(qidp->path)); > memcpy(&qidp->path, &stbuf->st_ino, size); > @@ -587,6 +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, > @@ -599,7 +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; > } > > @@ -830,7 +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; > @@ -891,7 +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)); > @@ -913,7 +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) > @@ -1115,7 +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) { > @@ -1136,7 +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) { > @@ -1381,7 +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)); > @@ -1483,7 +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) { > @@ -1593,7 +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; > @@ -2327,7 +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; > @@ -2384,7 +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; > @@ -3064,7 +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; > @@ -3222,7 +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; > @@ -3633,6 +3674,8 @@ int v9fs_device_realize_common(V9fsState *s, const V9fsTransport *t, > goto out; > } > > + s->dev_id = 0; > + Set it to stat->st_dev after lstat() was called later in this function. > s->ctx.fst = &fse->fst; > fsdev_throttle_init(s->ctx.fst); > > diff --git a/hw/9pfs/9p.h b/hw/9pfs/9p.h > index 8883761b2c..5e316178d5 100644 > --- a/hw/9pfs/9p.h > +++ b/hw/9pfs/9p.h > @@ -256,6 +256,7 @@ struct V9fsState > Error *migration_blocker; > V9fsConf fsconf; > V9fsQID root_qid; > + dev_t dev_id; > }; > > /* 9p2000.L open flags */
On Donnerstag, 27. Juni 2019 19:26:22 CEST Greg Kurz wrote: > On Wed, 26 Jun 2019 20:30:41 +0200 > > Christian Schoenebeck via Qemu-devel <qemu-devel@nongnu.org> wrote: > > 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 wiles within a device. > > s/wile/files Ah right. :) > > Here we track the device hosting the 9pfs share, in order > > to prevent security issues with QID path collisions from > > other devices. > > > > Signed-off-by: Antonios Motakis <antonios.motakis@huawei.com> > > You should mention here the changes you made to the original patch. Got it. Will do for the other cases as well of course. > > -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 == 0) { > > + pdu->s->dev_id = stbuf->st_dev; > > st_dev should be captured in v9fs_device_realize_common() since we > lstat() the root there, instead of every request doing the check. Ok. > > + } else if (pdu->s->dev_id != stbuf->st_dev) { > > + error_report_once( > > + "9p: Multiple devices detected in same VirtFS export. " > > + "You must use a separate export for each device." > > + ); > > + return -ENOSYS; > > This error is likely to end up as the return value of a > syscall in the guest and -ENOSYS usually means the syscall > isn't implemented, which is obviously not the case. Maybe > return -EPERM instead ? I would rather suggest -ENODEV. The entire device of the requested file/dir is not available on guest. -EPERM IMO rather motivates users looking for file system permission settings on individual files intead, and probably not checking the host's logs for the detailled error message. > > @@ -3633,6 +3674,8 @@ int v9fs_device_realize_common(V9fsState *s, const > > V9fsTransport *t,> > > goto out; > > > > } > > > > + s->dev_id = 0; > > + > > Set it to stat->st_dev after lstat() was called later in this function. I guesst you mean "earlier" not "later". The lstat() call is just before that dev_id initalization line. But in general your suggestion makes sense of course. Best regards, Christian Schoenebeck
On Fri, 28 Jun 2019 14:36:41 +0200 Christian Schoenebeck <qemu_oss@crudebyte.com> wrote: > On Donnerstag, 27. Juni 2019 19:26:22 CEST Greg Kurz wrote: > > On Wed, 26 Jun 2019 20:30:41 +0200 > > > > Christian Schoenebeck via Qemu-devel <qemu-devel@nongnu.org> wrote: > > > 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 wiles within a device. > > > > s/wile/files > > Ah right. :) > > > > Here we track the device hosting the 9pfs share, in order > > > to prevent security issues with QID path collisions from > > > other devices. > > > > > > Signed-off-by: Antonios Motakis <antonios.motakis@huawei.com> > > > > You should mention here the changes you made to the original patch. > > Got it. Will do for the other cases as well of course. > Cool. > > > -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 == 0) { > > > + pdu->s->dev_id = stbuf->st_dev; > > > > st_dev should be captured in v9fs_device_realize_common() since we > > lstat() the root there, instead of every request doing the check. > > Ok. > > > > + } else if (pdu->s->dev_id != stbuf->st_dev) { > > > + error_report_once( > > > + "9p: Multiple devices detected in same VirtFS export. " > > > + "You must use a separate export for each device." > > > + ); > > > + return -ENOSYS; > > > > This error is likely to end up as the return value of a > > syscall in the guest and -ENOSYS usually means the syscall > > isn't implemented, which is obviously not the case. Maybe > > return -EPERM instead ? > > I would rather suggest -ENODEV. The entire device of the requested file/dir is > not available on guest. > > -EPERM IMO rather motivates users looking for file system permission settings > on individual files intead, and probably not checking the host's logs for the > detailled error message. > -ENODEV is ok with me then. > > > @@ -3633,6 +3674,8 @@ int v9fs_device_realize_common(V9fsState *s, const > > > V9fsTransport *t,> > > > goto out; > > > > > > } > > > > > > + s->dev_id = 0; > > > + > > > > Set it to stat->st_dev after lstat() was called later in this function. > > I guesst you mean "earlier" not "later". The lstat() call is just before that > dev_id initalization line. But in general your suggestion makes sense of > course. > Oops... "earlier" indeed :) > Best regards, > Christian Schoenebeck
diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c index 586a6dccba..cbaa212625 100644 --- a/hw/9pfs/9p.c +++ b/hw/9pfs/9p.c @@ -572,10 +572,20 @@ 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 == 0) { + pdu->s->dev_id = stbuf->st_dev; + } else if (pdu->s->dev_id != stbuf->st_dev) { + error_report_once( + "9p: Multiple devices detected in same VirtFS export. " + "You must use a separate export for each device." + ); + return -ENOSYS; + } + memset(&qidp->path, 0, sizeof(qidp->path)); size = MIN(sizeof(stbuf->st_ino), sizeof(qidp->path)); memcpy(&qidp->path, &stbuf->st_ino, size); @@ -587,6 +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, @@ -599,7 +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; } @@ -830,7 +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; @@ -891,7 +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)); @@ -913,7 +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) @@ -1115,7 +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) { @@ -1136,7 +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) { @@ -1381,7 +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)); @@ -1483,7 +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) { @@ -1593,7 +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; @@ -2327,7 +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; @@ -2384,7 +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; @@ -3064,7 +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; @@ -3222,7 +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; @@ -3633,6 +3674,8 @@ int v9fs_device_realize_common(V9fsState *s, const V9fsTransport *t, goto out; } + s->dev_id = 0; + s->ctx.fst = &fse->fst; fsdev_throttle_init(s->ctx.fst); diff --git a/hw/9pfs/9p.h b/hw/9pfs/9p.h index 8883761b2c..5e316178d5 100644 --- a/hw/9pfs/9p.h +++ b/hw/9pfs/9p.h @@ -256,6 +256,7 @@ struct V9fsState Error *migration_blocker; V9fsConf fsconf; V9fsQID root_qid; + dev_t dev_id; }; /* 9p2000.L open flags */