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?

Thanks,

-- 
Shawn Webb
Cofounder / Security Engineer
HardenedBSD

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