On Tue, Apr 11, 2017 at 01:39:55PM -0500, Eric Sandeen wrote:
> On 4/11/17 1:33 PM, Brian Foster wrote:
> > On Tue, Apr 11, 2017 at 04:12:37PM +0200, Jan Tulak wrote:
> >> A dirty log in an obfuscated dump means that a corruption can happen
> >> when replaying the log (which contains unobfuscated data). Warn the user
> >> about this possibility.
> >>
> >> The xlog workaround is copy&paste solution from repair/phase2.c and
> >> other tools, because the function is not implemented in libxlog.
> >>
> >> Signed-off-by: Jan Tulak <jtulak@xxxxxxxxxx>
> >> ---
> >> mdrestore/Makefile | 4 +--
> >> mdrestore/xfs_mdrestore.c | 84 +++++++++++++++++++++++++++++++++++++++++++++++
> >> 2 files changed, 86 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/mdrestore/Makefile b/mdrestore/Makefile
> >> index 5171306..6355df9 100644
> >> --- a/mdrestore/Makefile
> >> +++ b/mdrestore/Makefile
> >> @@ -8,8 +8,8 @@ include $(TOPDIR)/include/builddefs
> >> LTCOMMAND = xfs_mdrestore
> >> CFILES = xfs_mdrestore.c
> >>
> >> -LLDLIBS = $(LIBXFS) $(LIBRT) $(LIBPTHREAD) $(LIBUUID)
> >> -LTDEPENDENCIES = $(LIBXFS)
> >> +LLDLIBS = $(LIBXFS) $(LIBXLOG) $(LIBRT) $(LIBPTHREAD) $(LIBUUID)
> >> +LTDEPENDENCIES = $(LIBXFS) $(LIBXLOG)
> >> LLDFLAGS = -static
> >>
> >
> > FYI, I get the following on a 'make -j 4':
> >
> > ...
> > Building mdrestore
> > gmake[3]: *** No rule to make target '../libxlog/libxlog.la', needed by 'xfs_mdrestore'. Stop.
> > gmake[3]: *** Waiting for unfinished jobs....
> >
> > It succeeds if I restart the build so I suspect something might be up
> > with the dependency tracking here.
>
>
> need something like this in the top Makefile:
>
> repair: libxlog libxcmd
> copy: libxlog
> mkfs: libxcmd
> +mdrestore: libxlog
>
>
> >> default: depend $(LTCOMMAND)
> >> diff --git a/mdrestore/xfs_mdrestore.c b/mdrestore/xfs_mdrestore.c
> >> index 0d399f1..3797955 100644
> >> --- a/mdrestore/xfs_mdrestore.c
> >> +++ b/mdrestore/xfs_mdrestore.c
> >> @@ -17,6 +17,7 @@
> >> */
> >>
> >> #include "libxfs.h"
> >> +#include "libxlog.h"
> >> #include "xfs_metadump.h"
> >>
> >> char *progname;
> >> @@ -190,6 +191,87 @@ perform_restore(
> >> free(metablock);
> >> }
> >>
> >> +/* workaround craziness in the xlog routines */
> >> +int xlog_recover_do_trans(struct xlog *log, xlog_recover_t *t, int p)
> >> +{
> >> + return 0;
> >> +}
> >> +
> >> +/*
> >> + * Warn if we just wrote a dump with a dirty log.
> >> + */
> >> +void
> >> +test_dirty_log(
> >> + bool is_target_file,
> >> + char* target_name)
> >> +{
> >> + struct xfs_sb *sbp;
> >> + struct xfs_buf *bp;
> >> + struct xfs_mount xmount;
> >> + struct xfs_mount *mp;
> >> + struct xlog xlog;
> >> + libxfs_init_t x;
> >> +
> >> + x.isreadonly = LIBXFS_ISREADONLY;
> >> + if (is_target_file) {
> >> + x.dname = target_name;
> >> + x.disfile = true;
> >> + } else {
> >> + x.disfile = false;
> >> + x.volname = target_name;
> >> + }
> >> +
> >> + if (!libxfs_init(&x)) {
> >> + fatal(_("\nfatal error -- couldn't initialize XFS library\n"),
> >> + strerror(errno));
> >> + }
> >> +
> >> + memset(&xmount, 0, sizeof(struct xfs_mount));
> >> + libxfs_buftarg_init(&xmount, x.ddev, x.logdev, x.rtdev);
> >> + bp = libxfs_readbuf(xmount.m_ddev_targp, XFS_SB_DADDR,
> >> + 1 << (XFS_MAX_SECTORSIZE_LOG - BBSHIFT), 0, NULL);
> >> +
> >> + if (!bp || bp->b_error) {
> >> + fprintf(stderr, _("%s: %s is invalid (cannot read first 512 "
> >> + "bytes)\n"), progname, target_name);
> >> + exit(1);
> >> + }
> >> +
> >> + /* copy SB from buffer to in-core, converting architecture as we go */
> >> + libxfs_sb_from_disk(&xmount.m_sb, XFS_BUF_TO_SBP(bp));
> >> + libxfs_putbuf(bp);
> >> + libxfs_purgebuf(bp);
> >> +
> >> + sbp = &xmount.m_sb;
> >> + mp = libxfs_mount(&xmount, sbp, x.ddev, x.logdev, x.rtdev,
> >> + LIBXFS_MOUNT_DEBUGGER);
> >> + if (!mp) {
> >> + fprintf(stderr,
> >> + _("%s: restored device %s unusable (not an XFS filesystem?)\n"),
> >> + progname, target_name);
> >> + exit(1);
> >> + }
> >
> > It might be cleaner to bury all of this init stuff in a separate init
> > function to be called before the log check. We also may not want to exit
> > the program if parsing the log or something happens to fail, given that
> > this is a debug tool.
>
> This is at the very end of restore, so the image is what it is at this point.
> But sure, no need to exit with failure I think, all it means is that we
> can't issue a meaningful warning.
>
>
> >> +
> >> + switch (xlog_is_dirty(mp, &xlog, &x,0)) {
> >> + case -1:
> >> + /* An error occured and we can't read the log. */
> >> + fprintf(stderr,
> >> + _("Warning: can't discern a log.\n"));
> >> + break;
> >> + case 1:
> >> + /* The log is dirty, warn. */
> >> + fprintf(stderr,
> >> + _("Warning: The log is dirty. If the image was obfuscated, "
> >> + "an attempt to replay the log may lead to corruption.\n"));
> >> + break;
> >
> > Then the above can remain in the test_log_dirty() helper or just be
> > open-coded at the end of main(), provided the mount was initialized
> > successfully (or we could still warn if we can't make sense of the log).
> >
> > BTW, this is going to warn on every xfs_mdrestore of an image with a
> > dirty log, right? That is slightly unfortunate, if so. Do we have any
> > method to track or determine whether an image is obfuscated (I'm
> > guessing not easily...)?
>
> Nope! There is an unused slot in the header, maybe we could add flags?
>
> Hm, or we could do a trick like setting the fs label to "OBFUSCATED"
> instead of "label" like we currently do. That might be reasonable...
>
> /* Replace any filesystem label with "L's" */
> if (obfuscate) {
> struct xfs_sb *sb = iocur_top->data;
> memset(sb->sb_fname, 'L',
> min(strlen(sb->sb_fname), sizeof(sb->sb_fname)));
> iocur_top->need_crc = 1;
> }
>
> (today we keep the same label length, but that's probably not
> necessary?)
>
That's an interesting idea. It looks like we currently set the fname to
L's when obfuscated. Could we just key off that in mdrestore?
Brian
> -Eric
>
> > Brian
> >
> >> + case 0:
> >> + /* Everything is ok. */
> >> + break;
> >> + }
> >> +
> >> +}
> >> +
> >> +
> >> static void
> >> usage(void)
> >> {
> >> @@ -271,5 +353,7 @@ main(
> >> if (src_f != stdin)
> >> fclose(src_f);
> >>
> >> + test_dirty_log(is_target_file, argv[optind]);
> >> +
> >> return 0;
> >> }
> >> --
> >> 2.1.4
> >>
> >> --
> >> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> >> the body of a message to majordomo@xxxxxxxxxxxxxxx
> >> More majordomo info at http://vger.kernel.org/majordomo-info.html
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> > the body of a message to majordomo@xxxxxxxxxxxxxxx
> > More majordomo info at http://vger.kernel.org/majordomo-info.html
> >
> --
> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at http://vger.kernel.org/majordomo-info.html
--
To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
