From 110243750dc4389fe8715c1db87a6ce6c2b9e645 Mon Sep 17 00:00:00 2001 From: Christian Schoenebeck Date: Fri, 4 Jun 2021 19:52:18 +0200 Subject: [PATCH] 9pfs: capture root stat We already capture the QID of the exported 9p root path, i.e. to prevent client access outside the defined, exported filesystem's tree. This is currently checked by comparing the root QID with another FID's QID. The problem with the latter is that resolving a QID of any given 9p path can only be done on 9p server's main thread, that's because it might mutate the server's state if inode remapping is enabled. For that reason also capture the POSIX stat info of the root path for being able to identify on any (e.g. worker) thread whether an arbitrary given path is identical to the export root. Signed-off-by: Christian Schoenebeck Reviewed-by: Greg Kurz Message-Id: --- hw/9pfs/9p.c | 10 +++++++++- hw/9pfs/9p.h | 1 + 2 files changed, 10 insertions(+), 1 deletion(-) diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c index e10a02f71d..eb15ec2082 100644 --- a/hw/9pfs/9p.c +++ b/hw/9pfs/9p.c @@ -1400,6 +1400,7 @@ static void coroutine_fn v9fs_attach(void *opaque) size_t offset = 7; V9fsQID qid; ssize_t err; + struct stat stbuf; v9fs_string_init(&uname); v9fs_string_init(&aname); @@ -1422,7 +1423,13 @@ static void coroutine_fn v9fs_attach(void *opaque) clunk_fid(s, fid); goto out; } - err = fid_to_qid(pdu, fidp, &qid); + err = v9fs_co_lstat(pdu, &fidp->path, &stbuf); + if (err < 0) { + err = -EINVAL; + clunk_fid(s, fid); + goto out; + } + err = stat_to_qid(pdu, &stbuf, &qid); if (err < 0) { err = -EINVAL; clunk_fid(s, fid); @@ -1455,6 +1462,7 @@ static void coroutine_fn v9fs_attach(void *opaque) err += offset; memcpy(&s->root_qid, &qid, sizeof(qid)); + memcpy(&s->root_st, &stbuf, sizeof(stbuf)); trace_v9fs_attach_return(pdu->tag, pdu->id, qid.type, qid.version, qid.path); out: diff --git a/hw/9pfs/9p.h b/hw/9pfs/9p.h index 00381591ff..6f0b4c78c0 100644 --- a/hw/9pfs/9p.h +++ b/hw/9pfs/9p.h @@ -356,6 +356,7 @@ struct V9fsState { Error *migration_blocker; V9fsConf fsconf; V9fsQID root_qid; + struct stat root_st; dev_t dev_id; struct qht qpd_table; struct qht qpp_table;