svn commit: r350315 - in head/sys: kern sys
Kyle Evans
kevans at freebsd.org
Thu Jul 25 16:49:13 UTC 2019
On Thu, Jul 25, 2019 at 11:46 AM Shawn Webb <shawn.webb at hardenedbsd.org> wrote:
>
> Hey Rick,
>
> On Thu, Jul 25, 2019 at 05:46:17AM +0000, Rick Macklem wrote:
> > Author: rmacklem
> > Date: Thu Jul 25 05:46:16 2019
> > New Revision: 350315
> > URL: https://svnweb.freebsd.org/changeset/base/350315
> >
> > Log:
> > Add kernel support for a Linux compatible copy_file_range(2) syscall.
> >
> > This patch adds support to the kernel for a Linux compatible
> > copy_file_range(2) syscall and the related VOP_COPY_FILE_RANGE(9).
> > This syscall/VOP can be used by the NFSv4.2 client to implement the
> > Copy operation against an NFSv4.2 server to do file copies locally on
> > the server.
> > The vn_generic_copy_file_range() function in this patch can be used
> > by the NFSv4.2 server to implement the Copy operation.
> > Fuse may also me able to use the VOP_COPY_FILE_RANGE() method.
> >
> > vn_generic_copy_file_range() attempts to maintain holes in the output
> > file in the range to be copied, but may fail to do so if the input and
> > output files are on different file systems with different _PC_MIN_HOLE_SIZE
> > values.
> >
> > Separate commits will be done for the generated syscall files and userland
> > changes. A commit for a compat32 syscall will be done later.
> >
> > Reviewed by: kib, asomers (plus comments by brooks, jilles)
> > Relnotes: yes
> > Differential Revision: https://reviews.freebsd.org/D20584
> >
> > Modified:
> > head/sys/kern/syscalls.master
> > head/sys/kern/vfs_default.c
> > head/sys/kern/vfs_syscalls.c
> > head/sys/kern/vfs_vnops.c
> > head/sys/kern/vnode_if.src
> > head/sys/sys/syscallsubr.h
> > head/sys/sys/vnode.h
> >
> > Modified: head/sys/kern/syscalls.master
> > ==============================================================================
> > --- head/sys/kern/syscalls.master Thu Jul 25 03:55:05 2019 (r350314)
> > +++ head/sys/kern/syscalls.master Thu Jul 25 05:46:16 2019 (r350315)
> > @@ -3175,6 +3175,16 @@
> > int flag
> > );
> > }
> > +569 AUE_NULL STD {
> > + ssize_t copy_file_range(
> > + int infd,
> > + _Inout_opt_ off_t *inoffp,
> > + int outfd,
> > + _Inout_opt_ off_t *outoffp,
> > + size_t len,
> > + unsigned int flags
> > + );
> > + }
> >
> > ; Please copy any additions and changes to the following compatability tables:
> > ; sys/compat/freebsd32/syscalls.master
> >
> > Modified: head/sys/kern/vfs_default.c
> > ==============================================================================
> > --- head/sys/kern/vfs_default.c Thu Jul 25 03:55:05 2019 (r350314)
> > +++ head/sys/kern/vfs_default.c Thu Jul 25 05:46:16 2019 (r350315)
> > @@ -83,6 +83,7 @@ static int dirent_exists(struct vnode *vp, const char
> > static int vop_stdis_text(struct vop_is_text_args *ap);
> > static int vop_stdunset_text(struct vop_unset_text_args *ap);
> > static int vop_stdadd_writecount(struct vop_add_writecount_args *ap);
> > +static int vop_stdcopy_file_range(struct vop_copy_file_range_args *ap);
> > static int vop_stdfdatasync(struct vop_fdatasync_args *ap);
> > static int vop_stdgetpages_async(struct vop_getpages_async_args *ap);
> >
> > @@ -140,6 +141,7 @@ struct vop_vector default_vnodeops = {
> > .vop_set_text = vop_stdset_text,
> > .vop_unset_text = vop_stdunset_text,
> > .vop_add_writecount = vop_stdadd_writecount,
> > + .vop_copy_file_range = vop_stdcopy_file_range,
> > };
> >
> > /*
> > @@ -1210,6 +1212,17 @@ vfs_stdnosync (mp, waitfor)
> > {
> >
> > return (0);
> > +}
> > +
> > +static int
> > +vop_stdcopy_file_range(struct vop_copy_file_range_args *ap)
> > +{
> > + int error;
> > +
> > + error = vn_generic_copy_file_range(ap->a_invp, ap->a_inoffp,
> > + ap->a_outvp, ap->a_outoffp, ap->a_lenp, ap->a_flags, ap->a_incred,
> > + ap->a_outcred, ap->a_fsizetd);
> > + return (error);
> > }
> >
> > int
> >
> > Modified: head/sys/kern/vfs_syscalls.c
> > ==============================================================================
> > --- head/sys/kern/vfs_syscalls.c Thu Jul 25 03:55:05 2019 (r350314)
> > +++ head/sys/kern/vfs_syscalls.c Thu Jul 25 05:46:16 2019 (r350315)
> > @@ -4814,3 +4814,122 @@ sys_posix_fadvise(struct thread *td, struct posix_fadv
> > uap->advice);
> > return (kern_posix_error(td, error));
> > }
> > +
> > +int
> > +kern_copy_file_range(struct thread *td, int infd, off_t *inoffp, int outfd,
> > + off_t *outoffp, size_t len, unsigned int flags)
> > +{
> > + struct file *infp, *outfp;
> > + struct vnode *invp, *outvp;
> > + int error;
> > + size_t retlen;
> > + void *rl_rcookie, *rl_wcookie;
> > + off_t savinoff, savoutoff;
> > +
> > + infp = outfp = NULL;
> > + rl_rcookie = rl_wcookie = NULL;
> > + savinoff = -1;
> > + error = 0;
> > + retlen = 0;
> > +
> > + if (flags != 0) {
> > + error = EINVAL;
> > + goto out;
> > + }
> > + if (len > SSIZE_MAX)
> > + /*
> > + * Although the len argument is size_t, the return argument
> > + * is ssize_t (which is signed). Therefore a size that won't
> > + * fit in ssize_t can't be returned.
> > + */
> > + len = SSIZE_MAX;
> > +
> > + /* Get the file structures for the file descriptors. */
> > + error = fget_read(td, infd, &cap_read_rights, &infp);
> > + if (error != 0)
> > + goto out;
> > + error = fget_write(td, outfd, &cap_write_rights, &outfp);
> > + if (error != 0)
> > + goto out;
> > +
> > + /* Set the offset pointers to the correct place. */
> > + if (inoffp == NULL)
> > + inoffp = &infp->f_offset;
> > + if (outoffp == NULL)
> > + outoffp = &outfp->f_offset;
> > + savinoff = *inoffp;
> > + savoutoff = *outoffp;
>
> Should these two lines, saving the old inoffp and outoffp, be moved
> before the two conditionals above?
>
Dereferencing potentially NULL pointers like that seems like a scary
proposition; I think this reads most correctly given the context.
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