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    SubjectRe: [PATCH RESEND v2 15/18] fuse: Add support for pid namespaces
    On Mon, Jan 04, 2016 at 12:03:54PM -0600, Seth Forshee wrote:
    > If the userspace process servicing fuse requests is running in
    > a pid namespace then pids passed via the fuse fd need to be
    > translated relative to that namespace. Capture the pid namespace
    > in use when the filesystem is mounted and use this for pid
    > translation.
    >
    > Since no use case currently exists for changing namespaces all
    > translations are done relative to the pid namespace in use when
    > /dev/fuse is opened.

    The above doesn't match what the patch does.

    - FUSE captures namespace at mount time

    - CUSE captures namespace at /dev/cuse open


    > Mounting or /dev/fuse IO from another
    > namespace will return errors.
    >
    > Requests from processes whose pid cannot be translated into the
    > target namespace are not permitted, except for requests
    > allocated via fuse_get_req_nofail_nopages. For no-fail requests
    > in.h.pid will be 0 if the pid translation fails.
    >
    > File locking changes based on previous work done by Eric
    > Biederman.
    >
    > Signed-off-by: Seth Forshee <seth.forshee@canonical.com>
    > Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>

    Not sure how my SOB got on this patch, use this instead:

    Acked-by: Miklos Szeredi <mszeredi@redhat.com>

    > ---
    > fs/fuse/dev.c | 19 +++++++++++++++----
    > fs/fuse/file.c | 22 +++++++++++++++++-----
    > fs/fuse/fuse_i.h | 4 ++++
    > fs/fuse/inode.c | 3 +++
    > 4 files changed, 39 insertions(+), 9 deletions(-)
    >
    > diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
    > index ebb5e37455a0..a4f6f30d6d86 100644
    > --- a/fs/fuse/dev.c
    > +++ b/fs/fuse/dev.c
    > @@ -19,6 +19,7 @@
    > #include <linux/pipe_fs_i.h>
    > #include <linux/swap.h>
    > #include <linux/splice.h>
    > +#include <linux/sched.h>
    >
    > MODULE_ALIAS_MISCDEV(FUSE_MINOR);
    > MODULE_ALIAS("devname:fuse");
    > @@ -124,11 +125,11 @@ static void __fuse_put_request(struct fuse_req *req)
    > atomic_dec(&req->count);
    > }
    >
    > -static void fuse_req_init_context(struct fuse_req *req)
    > +static void fuse_req_init_context(struct fuse_conn *fc, struct fuse_req *req)
    > {
    > req->in.h.uid = from_kuid_munged(&init_user_ns, current_fsuid());
    > req->in.h.gid = from_kgid_munged(&init_user_ns, current_fsgid());
    > - req->in.h.pid = current->pid;
    > + req->in.h.pid = pid_nr_ns(task_pid(current), fc->pid_ns);
    > }
    >
    > void fuse_set_initialized(struct fuse_conn *fc)
    > @@ -181,10 +182,14 @@ static struct fuse_req *__fuse_get_req(struct fuse_conn *fc, unsigned npages,
    > goto out;
    > }
    >
    > - fuse_req_init_context(req);
    > + fuse_req_init_context(fc, req);
    > __set_bit(FR_WAITING, &req->flags);
    > if (for_background)
    > __set_bit(FR_BACKGROUND, &req->flags);
    > + if (req->in.h.pid == 0) {
    > + fuse_put_request(fc, req);
    > + return ERR_PTR(-EOVERFLOW);
    > + }
    >
    > return req;
    >
    > @@ -274,7 +279,7 @@ struct fuse_req *fuse_get_req_nofail_nopages(struct fuse_conn *fc,
    > if (!req)
    > req = get_reserved_req(fc, file);
    >
    > - fuse_req_init_context(req);
    > + fuse_req_init_context(fc, req);
    > __set_bit(FR_WAITING, &req->flags);
    > __clear_bit(FR_BACKGROUND, &req->flags);
    > return req;
    > @@ -1243,6 +1248,9 @@ static ssize_t fuse_dev_do_read(struct fuse_dev *fud, struct file *file,
    > struct fuse_in *in;
    > unsigned reqsize;
    >
    > + if (task_active_pid_ns(current) != fc->pid_ns)
    > + return -EIO;
    > +
    > restart:
    > spin_lock(&fiq->waitq.lock);
    > err = -EAGAIN;
    > @@ -1872,6 +1880,9 @@ static ssize_t fuse_dev_do_write(struct fuse_dev *fud,
    > struct fuse_req *req;
    > struct fuse_out_header oh;
    >
    > + if (task_active_pid_ns(current) != fc->pid_ns)
    > + return -EIO;
    > +
    > if (nbytes < sizeof(struct fuse_out_header))
    > return -EINVAL;
    >
    > diff --git a/fs/fuse/file.c b/fs/fuse/file.c
    > index e0faf8f2c868..a6c7484c94ee 100644
    > --- a/fs/fuse/file.c
    > +++ b/fs/fuse/file.c
    > @@ -2061,7 +2061,8 @@ static int fuse_direct_mmap(struct file *file, struct vm_area_struct *vma)
    > return generic_file_mmap(file, vma);
    > }
    >
    > -static int convert_fuse_file_lock(const struct fuse_file_lock *ffl,
    > +static int convert_fuse_file_lock(struct fuse_conn *fc,
    > + const struct fuse_file_lock *ffl,
    > struct file_lock *fl)
    > {
    > switch (ffl->type) {
    > @@ -2076,7 +2077,14 @@ static int convert_fuse_file_lock(const struct fuse_file_lock *ffl,
    >
    > fl->fl_start = ffl->start;
    > fl->fl_end = ffl->end;
    > - fl->fl_pid = ffl->pid;
    > +
    > + /*
    > + * Convert pid into the caller's pid namespace. If the pid
    > + * does not map into the namespace fl_pid will get set to 0.
    > + */
    > + rcu_read_lock();
    > + fl->fl_pid = pid_vnr(find_pid_ns(ffl->pid, fc->pid_ns));
    > + rcu_read_unlock();
    > break;
    >
    > default:
    > @@ -2125,7 +2133,7 @@ static int fuse_getlk(struct file *file, struct file_lock *fl)
    > args.out.args[0].value = &outarg;
    > err = fuse_simple_request(fc, &args);
    > if (!err)
    > - err = convert_fuse_file_lock(&outarg.lk, fl);
    > + err = convert_fuse_file_lock(fc, &outarg.lk, fl);
    >
    > return err;
    > }
    > @@ -2137,7 +2145,8 @@ static int fuse_setlk(struct file *file, struct file_lock *fl, int flock)
    > FUSE_ARGS(args);
    > struct fuse_lk_in inarg;
    > int opcode = (fl->fl_flags & FL_SLEEP) ? FUSE_SETLKW : FUSE_SETLK;
    > - pid_t pid = fl->fl_type != F_UNLCK ? current->tgid : 0;
    > + struct pid *pid = fl->fl_type != F_UNLCK ? task_tgid(current) : NULL;
    > + pid_t pid_nr = pid_nr_ns(pid, fc->pid_ns);
    > int err;
    >
    > if (fl->fl_lmops && fl->fl_lmops->lm_grant) {
    > @@ -2149,7 +2158,10 @@ static int fuse_setlk(struct file *file, struct file_lock *fl, int flock)
    > if (fl->fl_flags & FL_CLOSE)
    > return 0;
    >
    > - fuse_lk_fill(&args, file, fl, opcode, pid, flock, &inarg);
    > + if (pid && pid_nr == 0)
    > + return -EOVERFLOW;
    > +
    > + fuse_lk_fill(&args, file, fl, opcode, pid_nr, flock, &inarg);
    > err = fuse_simple_request(fc, &args);
    >
    > /* locking is restartable */
    > diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
    > index 405113101db8..143b595197b6 100644
    > --- a/fs/fuse/fuse_i.h
    > +++ b/fs/fuse/fuse_i.h
    > @@ -22,6 +22,7 @@
    > #include <linux/rbtree.h>
    > #include <linux/poll.h>
    > #include <linux/workqueue.h>
    > +#include <linux/pid_namespace.h>
    >
    > /** Max number of pages that can be used in a single read request */
    > #define FUSE_MAX_PAGES_PER_REQ 32
    > @@ -456,6 +457,9 @@ struct fuse_conn {
    > /** The group id for this mount */
    > kgid_t group_id;
    >
    > + /** The pid namespace for this mount */
    > + struct pid_namespace *pid_ns;
    > +
    > /** The fuse mount flags for this mount */
    > unsigned flags;
    >
    > diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
    > index 2913db2a5b99..2f31874ea9db 100644
    > --- a/fs/fuse/inode.c
    > +++ b/fs/fuse/inode.c
    > @@ -20,6 +20,7 @@
    > #include <linux/random.h>
    > #include <linux/sched.h>
    > #include <linux/exportfs.h>
    > +#include <linux/pid_namespace.h>
    >
    > MODULE_AUTHOR("Miklos Szeredi <miklos@szeredi.hu>");
    > MODULE_DESCRIPTION("Filesystem in Userspace");
    > @@ -609,6 +610,7 @@ void fuse_conn_init(struct fuse_conn *fc)
    > fc->connected = 1;
    > fc->attr_version = 1;
    > get_random_bytes(&fc->scramble_key, sizeof(fc->scramble_key));
    > + fc->pid_ns = get_pid_ns(task_active_pid_ns(current));
    > }
    > EXPORT_SYMBOL_GPL(fuse_conn_init);
    >
    > @@ -617,6 +619,7 @@ void fuse_conn_put(struct fuse_conn *fc)
    > if (atomic_dec_and_test(&fc->count)) {
    > if (fc->destroy_req)
    > fuse_request_free(fc->destroy_req);
    > + put_pid_ns(fc->pid_ns);
    > fc->release(fc);
    > }
    > }
    > --
    > 1.9.1
    >

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