On Wed, 3 Oct 2018 00:40:27 +0000
Rick Macklem <rmack...@uoguelph.ca> wrote:
> Hi,
>
> I am working on updating "struct export_args" to fix/add a few things.
> One of these is that "ex_flags" is an int, but the flags are defined in
> mount.h
> as MNT_xx bits that now exceed 32bits (mnt_flag is now uint64_t).
> For now, this doesn't break anything, since the flags used by ex_flags are
> all defined in the low order 32bits but...it seems like this should be
> addressed
> by a new version of "struct export_args".
>
> I have two versions of the updated structure:
> A)
> struct export_args {
> uint64_t ex_flags; /* export related flags */
> uid_t ex_root; /* mapping for root uid */
> struct xucred ex_anon; /* mapping for anonymous user */
> struct sockaddr *ex_addr; /* net address to which exported */
> u_char ex_addrlen; /* and the net address length */
> struct sockaddr *ex_mask; /* mask of valid bits in saddr */
> u_char ex_masklen; /* and the smask length */
> char *ex_indexfile; /* index file for WebNFS URLs */
> int ex_numsecflavors; /* security flavor count */
> int ex_secflavors[MAXSECFLAVORS]; /* list of security flavors */
> int32_t ex_fsid; /* mnt_stat.f_fsid.val[0] if */
> /* MNT_EXPORTFSID set in ex_flags64 */
> gid_t *ex_suppgroups; /* Supplemental groups if */
> /* ex_anon.cr_ngroups > XU_NGROUPS */
> };
> B)
> struct export_args {
> int ex_flags; /* export related flags */
> uid_t ex_root; /* mapping for root uid */
> struct xucred ex_anon; /* mapping for anonymous user */
> struct sockaddr *ex_addr; /* net address to which exported */
> u_char ex_addrlen; /* and the net address length */
> struct sockaddr *ex_mask; /* mask of valid bits in saddr */
> u_char ex_masklen; /* and the smask length */
> char *ex_indexfile; /* index file for WebNFS URLs */
> int ex_numsecflavors; /* security flavor count */
> int ex_secflavors[MAXSECFLAVORS]; /* list of security flavors */
> uint64_t ex_flagshighbits; /* High order bits of mnt_flag */
> int32_t ex_fsid; /* mnt_stat.f_fsid.val[0] if */
> /* MNT_EXPORTFSID set in ex_flags64 */
> gid_t *ex_suppgroups; /* Supplemental groups if */
> /* ex_anon.cr_ngroups > XU_NGROUPS */
> };
>
> A) does the obvious thing. Unfortunately, this changes the vfs KABI
> (specifically the function vfs_oexport_conv()) such that a file system
> module compiled with an unpatched mount.h could crash a patched system.
> As such, I think it couldn't be MFC'd and would be stuck in head/current
> until FreeBSD13 (or FreeBSD14 if 13 gets skipped over;-).
>
> B) doesn't change any fields, but adds a second ex_flagshighbits for the high
> order bit. Since it only adds fields where none of those bits are used after
> the exports are processed by vfs_export() and, as such, will not break
> the VFS KABI, since vfs_domount_update() differentiates which version
> of export_args is being used.
> As such, I believe this version can be MFC'd. However, it does seem confusing
> to have the two ex_flags fields for the low and high 32bits.
>
> So, which do you think it preferable? rick
> ps: Josh Paetzel has volunteered to do the mountd.c changes and I have a kerne
> patch that I'll put up on phabricator once Josh has been able to test
> it.
>
In B, shouldn't ex_flags become uint32_t if all 32 bits can contain
flag bits? And why make ex_flagshighbits a uint64_t? You could
make it uint32_t and simply shift the high bits around.
--
Gary Jennejohn
_______________________________________________
freebsd-current@freebsd.org mailing list
https://lists.freebsd.org/mailman/listinfo/freebsd-current
To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org"
