From: Greg Kurz <gr...@kaod.org> Empty path components don't make sense for most commands and may cause undefined behavior, depending on the backend.
Also, the walk request described in the 9P spec [1] clearly shows that the client is supposed to send individual path components: the official linux client never sends portions of path containing the / character for example. Moreover, the 9P spec [2] also states that a system can decide to restrict the set of supported characters used in path components, with an explicit mention "to remove slashes from name components". This patch introduces a new name_is_illegal() helper that checks the names sent by the client are not empty and don't contain unwanted chars. Since 9pfs is only supported on linux hosts, only the / character is checked at the moment. When support for other hosts (AKA. win32) is added, other chars may need to be blacklisted as well. If a client sends an illegal path component, the request will fail and ENOENT is returned to the client. [1] http://man.cat-v.org/plan_9/5/walk [2] http://man.cat-v.org/plan_9/5/intro Suggested-by: Peter Maydell <peter.mayd...@linaro.org> Signed-off-by: Greg Kurz <gr...@kaod.org> Reviewed-by: Eric Blake <ebl...@redhat.com> Reviewed-by: Michael S. Tsirkin <m...@redhat.com> Signed-off-by: Peter Maydell <peter.mayd...@linaro.org> (cherry picked from commit fff39a7ad09da07ef490de05c92c91f22f8002f2) Signed-off-by: Michael Roth <mdr...@linux.vnet.ibm.com> --- hw/9pfs/9p.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 56 insertions(+) diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c index f5e3012..53c466b 100644 --- a/hw/9pfs/9p.c +++ b/hw/9pfs/9p.c @@ -1254,6 +1254,11 @@ static int v9fs_walk_marshal(V9fsPDU *pdu, uint16_t nwnames, V9fsQID *qids) return offset; } +static bool name_is_illegal(const char *name) +{ + return !*name || strchr(name, '/') != NULL; +} + static void v9fs_walk(void *opaque) { int name_idx; @@ -1287,6 +1292,10 @@ static void v9fs_walk(void *opaque) if (err < 0) { goto out_nofid; } + if (name_is_illegal(wnames[i].data)) { + err = -ENOENT; + goto out_nofid; + } offset += err; } } else if (nwnames > P9_MAXWELEM) { @@ -1481,6 +1490,11 @@ static void v9fs_lcreate(void *opaque) } trace_v9fs_lcreate(pdu->tag, pdu->id, dfid, flags, mode, gid); + if (name_is_illegal(name.data)) { + err = -ENOENT; + goto out_nofid; + } + fidp = get_fid(pdu, dfid); if (fidp == NULL) { err = -ENOENT; @@ -2066,6 +2080,11 @@ static void v9fs_create(void *opaque) } trace_v9fs_create(pdu->tag, pdu->id, fid, name.data, perm, mode); + if (name_is_illegal(name.data)) { + err = -ENOENT; + goto out_nofid; + } + fidp = get_fid(pdu, fid); if (fidp == NULL) { err = -EINVAL; @@ -2231,6 +2250,11 @@ static void v9fs_symlink(void *opaque) } trace_v9fs_symlink(pdu->tag, pdu->id, dfid, name.data, symname.data, gid); + if (name_is_illegal(name.data)) { + err = -ENOENT; + goto out_nofid; + } + dfidp = get_fid(pdu, dfid); if (dfidp == NULL) { err = -EINVAL; @@ -2305,6 +2329,11 @@ static void v9fs_link(void *opaque) } trace_v9fs_link(pdu->tag, pdu->id, dfid, oldfid, name.data); + if (name_is_illegal(name.data)) { + err = -ENOENT; + goto out_nofid; + } + dfidp = get_fid(pdu, dfid); if (dfidp == NULL) { err = -ENOENT; @@ -2387,6 +2416,12 @@ static void v9fs_unlinkat(void *opaque) if (err < 0) { goto out_nofid; } + + if (name_is_illegal(name.data)) { + err = -ENOENT; + goto out_nofid; + } + dfidp = get_fid(pdu, dfid); if (dfidp == NULL) { err = -EINVAL; @@ -2493,6 +2528,12 @@ static void v9fs_rename(void *opaque) if (err < 0) { goto out_nofid; } + + if (name_is_illegal(name.data)) { + err = -ENOENT; + goto out_nofid; + } + fidp = get_fid(pdu, fid); if (fidp == NULL) { err = -ENOENT; @@ -2605,6 +2646,11 @@ static void v9fs_renameat(void *opaque) goto out_err; } + if (name_is_illegal(old_name.data) || name_is_illegal(new_name.data)) { + err = -ENOENT; + goto out_err; + } + v9fs_path_write_lock(s); err = v9fs_complete_renameat(pdu, olddirfid, &old_name, newdirfid, &new_name); @@ -2815,6 +2861,11 @@ static void v9fs_mknod(void *opaque) } trace_v9fs_mknod(pdu->tag, pdu->id, fid, mode, major, minor); + if (name_is_illegal(name.data)) { + err = -ENOENT; + goto out_nofid; + } + fidp = get_fid(pdu, fid); if (fidp == NULL) { err = -ENOENT; @@ -2966,6 +3017,11 @@ static void v9fs_mkdir(void *opaque) } trace_v9fs_mkdir(pdu->tag, pdu->id, fid, name.data, mode, gid); + if (name_is_illegal(name.data)) { + err = -ENOENT; + goto out_nofid; + } + fidp = get_fid(pdu, fid); if (fidp == NULL) { err = -ENOENT; -- 1.9.1
