9pfs: local: fix unlink of alien files in mapped-file mode
When trying to remove a file from a directory, both created in non-mapped mode, the file remains and EBADF is returned to the guest. This is a regression introduced by commit "df4938a6 9pfs: local: unlinkat: don't follow symlinks" when fixing CVE-2016-9602. It changed the way we unlink the metadata file from ret = remove("$dir/.virtfs_metadata/$name"); if (ret < 0 && errno != ENOENT) { /* Error out */ } /* Ignore absence of metadata */ to fd = openat("$dir/.virtfs_metadata") unlinkat(fd, "$name") if (ret < 0 && errno != ENOENT) { /* Error out */ } /* Ignore absence of metadata */ If $dir was created in non-mapped mode, openat() fails with ENOENT and we pass -1 to unlinkat(), which fails in turn with EBADF. We just need to check the return of openat() and ignore ENOENT, in order to restore the behaviour we had with remove(). Signed-off-by: NGreg Kurz <groug@kaod.org> Reviewed-by: NEric Blake <eblake@redhat.com> [groug: rewrote the comments as suggested by Eric]
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