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[82.30.61.225]) by smtp.gmail.com with ESMTPSA id m8sm1388784wms.4.2022.02.17.05.36.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 17 Feb 2022 05:36:54 -0800 (PST) Date: Thu, 17 Feb 2022 13:36:52 +0000 From: "Dr. David Alan Gilbert" To: Vivek Goyal Subject: Re: [Virtio-fs] [PULL 00/12] virtiofs queue Message-ID: References: <20220216173625.128109-1-dgilbert@redhat.com> MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/2.1.5 (2021-12-30) Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dgilbert@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=170.10.129.124; envelope-from=dgilbert@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.082, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: virtio-fs@redhat.com, sebastian.hasler@stuvus.uni-stuttgart.de, qemu-devel@nongnu.org, groug@kaod.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Vivek Goyal (vgoyal@redhat.com) wrote: > On Wed, Feb 16, 2022 at 07:40:14PM +0000, Dr. David Alan Gilbert wrote: > > * Dr. David Alan Gilbert (git) (dgilbert@redhat.com) wrote: > > > From: "Dr. David Alan Gilbert" > > > > > > The following changes since commit c13b8e9973635f34f3ce4356af27a311c993729c: > > > > > > Merge remote-tracking branch 'remotes/alistair/tags/pull-riscv-to-apply-20220216' into staging (2022-02-16 09:57:11 +0000) > > > > > > are available in the Git repository at: > > > > > > https://gitlab.com/dagrh/qemu.git tags/pull-virtiofs-20220216 > > > > > > for you to fetch changes up to 47cc3ef597b2ee926c13c9433f4f73645429e128: > > > > > > virtiofsd: Add basic support for FUSE_SYNCFS request (2022-02-16 17:29:32 +0000) > > > > NAK > > this doesn't build on older Linuxes. > > > > Rework version in the works. > > Hi David, > > I think it is patch 8 which is using gettid(). I have updated that > patch and now I am using syscall(NR_gettid) instead. Here is the > updated patch. I hope this solves the build on older Linux issue. > > > Subject: virtiofsd: Add helpers to work with /proc/self/task/tid/attr/fscreate > > Soon we will be able to create and also set security context on the file > atomically using /proc/self/task/tid/attr/fscreate knob. If this knob > is available on the system, first set the knob with the desired context > and then create the file. It will be created with the context set in > fscreate. This works basically for SELinux and its per thread. > > This patch just introduces the helper functions. Subsequent patches will > make use of these helpers. > > Reviewed-by: Dr. David Alan Gilbert > Signed-off-by: Vivek Goyal Thanks, I'll merge that in. Dave > --- > tools/virtiofsd/passthrough_ll.c | 92 +++++++++++++++++++++++++++++++++++++++ > 1 file changed, 92 insertions(+) > > Index: rhvgoyal-qemu/tools/virtiofsd/passthrough_ll.c > =================================================================== > --- rhvgoyal-qemu.orig/tools/virtiofsd/passthrough_ll.c 2022-02-16 15:53:13.657015138 -0500 > +++ rhvgoyal-qemu/tools/virtiofsd/passthrough_ll.c 2022-02-16 15:55:14.911234993 -0500 > @@ -173,10 +173,14 @@ struct lo_data { > > /* An O_PATH file descriptor to /proc/self/fd/ */ > int proc_self_fd; > + /* An O_PATH file descriptor to /proc/self/task/ */ > + int proc_self_task; > int user_killpriv_v2, killpriv_v2; > /* If set, virtiofsd is responsible for setting umask during creation */ > bool change_umask; > int user_posix_acl, posix_acl; > + /* Keeps track if /proc//attr/fscreate should be used or not */ > + bool use_fscreate; > }; > > static const struct fuse_opt lo_opts[] = { > @@ -257,6 +261,72 @@ static struct lo_data *lo_data(fuse_req_ > } > > /* > + * Tries to figure out if /proc//attr/fscreate is usable or not. With > + * selinux=0, read from fscreate returns -EINVAL. > + * > + * TODO: Link with libselinux and use is_selinux_enabled() instead down > + * the line. It probably will be more reliable indicator. > + */ > +static bool is_fscreate_usable(struct lo_data *lo) > +{ > + char procname[64]; > + int fscreate_fd; > + size_t bytes_read; > + > + sprintf(procname, "%ld/attr/fscreate", syscall(SYS_gettid)); > + fscreate_fd = openat(lo->proc_self_task, procname, O_RDWR); > + if (fscreate_fd == -1) { > + return false; > + } > + > + bytes_read = read(fscreate_fd, procname, 64); > + close(fscreate_fd); > + if (bytes_read == -1) { > + return false; > + } > + return true; > +} > + > +/* Helpers to set/reset fscreate */ > +__attribute__((unused)) > +static int open_set_proc_fscreate(struct lo_data *lo, const void *ctx, > + size_t ctxlen,int *fd) > +{ > + char procname[64]; > + int fscreate_fd, err = 0; > + size_t written; > + > + sprintf(procname, "%ld/attr/fscreate", syscall(SYS_gettid)); > + fscreate_fd = openat(lo->proc_self_task, procname, O_WRONLY); > + err = fscreate_fd == -1 ? errno : 0; > + if (err) { > + return err; > + } > + > + written = write(fscreate_fd, ctx, ctxlen); > + err = written == -1 ? errno : 0; > + if (err) { > + goto out; > + } > + > + *fd = fscreate_fd; > + return 0; > +out: > + close(fscreate_fd); > + return err; > +} > + > +__attribute__((unused)) > +static void close_reset_proc_fscreate(int fd) > +{ > + if ((write(fd, NULL, 0)) == -1) { > + fuse_log(FUSE_LOG_WARNING, "Failed to reset fscreate. err=%d\n", errno); > + } > + close(fd); > + return; > +} > + > +/* > * Load capng's state from our saved state if the current thread > * hadn't previously been loaded. > * returns 0 on success > @@ -3522,6 +3592,15 @@ static void setup_namespaces(struct lo_d > exit(1); > } > > + /* Get the /proc/self/task descriptor */ > + lo->proc_self_task = open("/proc/self/task/", O_PATH); > + if (lo->proc_self_task == -1) { > + fuse_log(FUSE_LOG_ERR, "open(/proc/self/task, O_PATH): %m\n"); > + exit(1); > + } > + > + lo->use_fscreate = is_fscreate_usable(lo); > + > /* > * We only need /proc/self/fd. Prevent ".." from accessing parent > * directories of /proc/self/fd by bind-mounting it over /proc. Since / was > @@ -3738,6 +3817,14 @@ static void setup_chroot(struct lo_data > exit(1); > } > > + lo->proc_self_task = open("/proc/self/task", O_PATH); > + if (lo->proc_self_fd == -1) { > + fuse_log(FUSE_LOG_ERR, "open(\"/proc/self/task\", O_PATH): %m\n"); > + exit(1); > + } > + > + lo->use_fscreate = is_fscreate_usable(lo); > + > /* > * Make the shared directory the file system root so that FUSE_OPEN > * (lo_open()) cannot escape the shared directory by opening a symlink. > @@ -3923,6 +4010,10 @@ static void fuse_lo_data_cleanup(struct > close(lo->proc_self_fd); > } > > + if (lo->proc_self_task >= 0) { > + close(lo->proc_self_task); > + } > + > if (lo->root.fd >= 0) { > close(lo->root.fd); > } > @@ -3950,6 +4041,7 @@ int main(int argc, char *argv[]) > .posix_lock = 0, > .allow_direct_io = 0, > .proc_self_fd = -1, > + .proc_self_task = -1, > .user_killpriv_v2 = -1, > .user_posix_acl = -1, > }; > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK