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Blame 0055-virtiofsd-prevent-.-escape-in-lo_do_lookup.patch

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From: Stefan Hajnoczi <stefanha@redhat.com>
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Date: Mon, 27 Jan 2020 19:01:24 +0000
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Subject: [PATCH] virtiofsd: prevent ".." escape in lo_do_lookup()
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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Reviewed-by: Sergio Lopez <slp@redhat.com>
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Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
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(cherry picked from commit 854684bc0b3d63eb90b3abdfe471c2e4271ef176)
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---
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 tools/virtiofsd/passthrough_ll.c | 7 ++++++-
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 1 file changed, 6 insertions(+), 1 deletion(-)
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diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
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index e375406160..79d5966eea 100644
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--- a/tools/virtiofsd/passthrough_ll.c
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+++ b/tools/virtiofsd/passthrough_ll.c
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@@ -624,12 +624,17 @@ static int lo_do_lookup(fuse_req_t req, fuse_ino_t parent, const char *name,
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     int res;
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     int saverr;
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     struct lo_data *lo = lo_data(req);
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-    struct lo_inode *inode;
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+    struct lo_inode *inode, *dir = lo_inode(req, parent);
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     memset(e, 0, sizeof(*e));
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     e->attr_timeout = lo->timeout;
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     e->entry_timeout = lo->timeout;
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+    /* Do not allow escaping root directory */
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+    if (dir == &lo->root && strcmp(name, "..") == 0) {
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+        name = ".";
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+    }
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+
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     newfd = openat(lo_fd(req, parent), name, O_PATH | O_NOFOLLOW);
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     if (newfd == -1) {
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         goto out_err;