On 5/12/16 5:35 PM, Dave Chinner wrote:
> From: Dave Chinner <dchinner@xxxxxxxxxx>
>
> Currently we can't write corrupt structures with valid CRCs on v5
> filesystems via xfs_db. TO emulate certain types of corruption
> result from software bugs in the kernel code, we need this
> capability to set up the corrupted state. i.e. corrupt state with a
> valid CRC needs to appear on disk.
>
> This requires us to avoid running the verifier that would otherwise
> prevent writing corrupt state to disk. To enable this, add the CRC
> offset to the type table for different buffers and add a new flag to
> the write command to trigger running a CRC calculation base don this
> type table. We can then insert the calculated value into the correct
> location in the buffer...
>
> Because some objects are not directly buffer based, we can't easily
> do this CRC trick. Those object types will be marked as
> TYP_NO_CRC_OFF, and as a result will emit an error such as:
Using "TYP_NO_CRC_OFF" seems a little weird from a naming perspective;
it's not really a TYP_* is it? Its opposite is things like
XFS_AGI_CRC_OFF; NO_FIXED_CRC_OFF might be better to not confuse it
with the TYP_ on-disk types? Just a thought.
Functionally this looks fine; I have several non-functional suggestions
above & below that you can take or leave as you see fit on commit, so:
Reviewed-by: Eric Sandeen <sandeen@xxxxxxxxxx>
>
> # xfs_db -x -c "inode 96" -c "write -d magic 0x4949" /dev/ram0
> Cannot recalculate CRCs on this type of object
> #
>
> All v4 superblock types are configured this way, as are inode,
> dquots and other v5 metadata types that either don't have CRCs or
> don't have a fixed offset into a buffer to store their CRC.
>
> Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
> ---
> db/io.c | 7 ++++
> db/io.h | 1 +
> db/type.c | 137 +++++++++++++++++++++++++++++++++----------------------------
> db/type.h | 2 +
> db/write.c | 52 +++++++++++++++++------
> 5 files changed, 124 insertions(+), 75 deletions(-)
>
> diff --git a/db/io.c b/db/io.c
> index 9452e07..91cab12 100644
> --- a/db/io.c
> +++ b/db/io.c
> @@ -464,6 +464,13 @@ xfs_dummy_verify(
> }
>
> void
> +xfs_verify_recalc_crc(
> + struct xfs_buf *bp)
> +{
> + xfs_buf_update_cksum(bp, iocur_top->typ->crc_off);
> +}
> +
> +void
> write_cur(void)
> {
> if (iocur_sp < 0) {
> diff --git a/db/io.h b/db/io.h
> index 6201d7b..c69e9ce 100644
> --- a/db/io.h
> +++ b/db/io.h
> @@ -64,6 +64,7 @@ extern void set_cur(const struct typ *t, __int64_t d, int c, int ring_add,
> extern void ring_add(void);
> extern void set_iocur_type(const struct typ *t);
> extern void xfs_dummy_verify(struct xfs_buf *bp);
> +extern void xfs_verify_recalc_crc(struct xfs_buf *bp);
>
> /*
> * returns -1 for unchecked, 0 for bad and 1 for good
> diff --git a/db/type.c b/db/type.c
> index 1da7ee1..d061bc1 100644
> --- a/db/type.c
> +++ b/db/type.c
> @@ -50,99 +50,110 @@ static const cmdinfo_t type_cmd =
> N_("set/show current data type"), NULL };
>
> static const typ_t __typtab[] = {
> - { TYP_AGF, "agf", handle_struct, agf_hfld, NULL },
> - { TYP_AGFL, "agfl", handle_struct, agfl_hfld, NULL },
> - { TYP_AGI, "agi", handle_struct, agi_hfld, NULL },
> - { TYP_ATTR, "attr", handle_struct, attr_hfld, NULL },
> - { TYP_BMAPBTA, "bmapbta", handle_struct, bmapbta_hfld, NULL },
> - { TYP_BMAPBTD, "bmapbtd", handle_struct, bmapbtd_hfld, NULL },
> - { TYP_BNOBT, "bnobt", handle_struct, bnobt_hfld, NULL },
> - { TYP_CNTBT, "cntbt", handle_struct, cntbt_hfld, NULL },
> - { TYP_DATA, "data", handle_block, NULL, NULL },
> - { TYP_DIR2, "dir2", handle_struct, dir2_hfld, NULL },
> - { TYP_DQBLK, "dqblk", handle_struct, dqblk_hfld, NULL },
> - { TYP_INOBT, "inobt", handle_struct, inobt_hfld, NULL },
> - { TYP_INODATA, "inodata", NULL, NULL, NULL },
> - { TYP_INODE, "inode", handle_struct, inode_hfld, NULL },
> - { TYP_LOG, "log", NULL, NULL, NULL },
> - { TYP_RTBITMAP, "rtbitmap", NULL, NULL, NULL },
> - { TYP_RTSUMMARY, "rtsummary", NULL, NULL, NULL },
> - { TYP_SB, "sb", handle_struct, sb_hfld, NULL },
> - { TYP_SYMLINK, "symlink", handle_string, NULL, NULL },
> - { TYP_TEXT, "text", handle_text, NULL, NULL },
> - { TYP_FINOBT, "finobt", handle_struct, inobt_hfld, NULL },
> + { TYP_AGF, "agf", handle_struct, agf_hfld, NULL, TYP_NO_CRC_OFF },
> + { TYP_AGFL, "agfl", handle_struct, agfl_hfld, NULL, TYP_NO_CRC_OFF },
> + { TYP_AGI, "agi", handle_struct, agi_hfld, NULL, TYP_NO_CRC_OFF },
> + { TYP_ATTR, "attr", handle_struct, attr_hfld, NULL, TYP_NO_CRC_OFF },
> + { TYP_BMAPBTA, "bmapbta", handle_struct, bmapbta_hfld, NULL,
> + TYP_NO_CRC_OFF },
> + { TYP_BMAPBTD, "bmapbtd", handle_struct, bmapbtd_hfld, NULL,
> + TYP_NO_CRC_OFF },
> + { TYP_BNOBT, "bnobt", handle_struct, bnobt_hfld, NULL, TYP_NO_CRC_OFF },
> + { TYP_CNTBT, "cntbt", handle_struct, cntbt_hfld, NULL, TYP_NO_CRC_OFF },
> + { TYP_DATA, "data", handle_block, NULL, NULL, TYP_NO_CRC_OFF },
> + { TYP_DIR2, "dir2", handle_struct, dir2_hfld, NULL, TYP_NO_CRC_OFF },
> + { TYP_DQBLK, "dqblk", handle_struct, dqblk_hfld, NULL, TYP_NO_CRC_OFF },
> + { TYP_INOBT, "inobt", handle_struct, inobt_hfld, NULL, TYP_NO_CRC_OFF },
> + { TYP_INODATA, "inodata", NULL, NULL, NULL, TYP_NO_CRC_OFF },
> + { TYP_INODE, "inode", handle_struct, inode_hfld, NULL, TYP_NO_CRC_OFF },
> + { TYP_LOG, "log", NULL, NULL, NULL, TYP_NO_CRC_OFF },
> + { TYP_RTBITMAP, "rtbitmap", NULL, NULL, NULL, TYP_NO_CRC_OFF },
> + { TYP_RTSUMMARY, "rtsummary", NULL, NULL, NULL, TYP_NO_CRC_OFF },
> + { TYP_SB, "sb", handle_struct, sb_hfld, NULL, TYP_NO_CRC_OFF },
> + { TYP_SYMLINK, "symlink", handle_string, NULL, NULL, TYP_NO_CRC_OFF },
> + { TYP_TEXT, "text", handle_text, NULL, NULL, TYP_NO_CRC_OFF },
> + { TYP_FINOBT, "finobt", handle_struct, inobt_hfld, NULL,
> + TYP_NO_CRC_OFF },
> { TYP_NONE, NULL }
> };
>
> static const typ_t __typtab_crc[] = {
> - { TYP_AGF, "agf", handle_struct, agf_hfld, &xfs_agf_buf_ops },
> - { TYP_AGFL, "agfl", handle_struct, agfl_crc_hfld, &xfs_agfl_buf_ops },
> - { TYP_AGI, "agi", handle_struct, agi_hfld, &xfs_agi_buf_ops },
> + { TYP_AGF, "agf", handle_struct, agf_hfld, &xfs_agf_buf_ops,
> + XFS_AGF_CRC_OFF },
> + { TYP_AGFL, "agfl", handle_struct, agfl_crc_hfld, &xfs_agfl_buf_ops,
> + XFS_AGFL_CRC_OFF },
> + { TYP_AGI, "agi", handle_struct, agi_hfld, &xfs_agi_buf_ops,
> + XFS_AGI_CRC_OFF },
> { TYP_ATTR, "attr3", handle_struct, attr3_hfld,
> - &xfs_attr3_db_buf_ops },
> + &xfs_attr3_db_buf_ops, TYP_NO_CRC_OFF },
> { TYP_BMAPBTA, "bmapbta", handle_struct, bmapbta_crc_hfld,
> - &xfs_bmbt_buf_ops },
> + &xfs_bmbt_buf_ops, XFS_BTREE_LBLOCK_CRC_OFF },
> { TYP_BMAPBTD, "bmapbtd", handle_struct, bmapbtd_crc_hfld,
> - &xfs_bmbt_buf_ops },
> + &xfs_bmbt_buf_ops, XFS_BTREE_LBLOCK_CRC_OFF },
> { TYP_BNOBT, "bnobt", handle_struct, bnobt_crc_hfld,
> - &xfs_allocbt_buf_ops },
> + &xfs_allocbt_buf_ops, XFS_BTREE_SBLOCK_CRC_OFF },
> { TYP_CNTBT, "cntbt", handle_struct, cntbt_crc_hfld,
> - &xfs_allocbt_buf_ops },
> - { TYP_DATA, "data", handle_block, NULL, NULL },
> + &xfs_allocbt_buf_ops, XFS_BTREE_SBLOCK_CRC_OFF },
> + { TYP_DATA, "data", handle_block, NULL, NULL, TYP_NO_CRC_OFF },
> { TYP_DIR2, "dir3", handle_struct, dir3_hfld,
> - &xfs_dir3_db_buf_ops },
> + &xfs_dir3_db_buf_ops, TYP_NO_CRC_OFF },
> { TYP_DQBLK, "dqblk", handle_struct, dqblk_hfld,
> - &xfs_dquot_buf_ops },
> + &xfs_dquot_buf_ops, TYP_NO_CRC_OFF },
> { TYP_INOBT, "inobt", handle_struct, inobt_crc_hfld,
> - &xfs_inobt_buf_ops },
> - { TYP_INODATA, "inodata", NULL, NULL, NULL },
> + &xfs_inobt_buf_ops, XFS_BTREE_SBLOCK_CRC_OFF },
> + { TYP_INODATA, "inodata", NULL, NULL, NULL, TYP_NO_CRC_OFF },
> { TYP_INODE, "inode", handle_struct, inode_crc_hfld,
> - &xfs_inode_buf_ops },
> - { TYP_LOG, "log", NULL, NULL, NULL },
> - { TYP_RTBITMAP, "rtbitmap", NULL, NULL, NULL },
> - { TYP_RTSUMMARY, "rtsummary", NULL, NULL, NULL },
> - { TYP_SB, "sb", handle_struct, sb_hfld, &xfs_sb_buf_ops },
> + &xfs_inode_buf_ops, TYP_NO_CRC_OFF },
> + { TYP_LOG, "log", NULL, NULL, NULL, TYP_NO_CRC_OFF },
> + { TYP_RTBITMAP, "rtbitmap", NULL, NULL, NULL, TYP_NO_CRC_OFF },
> + { TYP_RTSUMMARY, "rtsummary", NULL, NULL, NULL, TYP_NO_CRC_OFF },
> + { TYP_SB, "sb", handle_struct, sb_hfld, &xfs_sb_buf_ops,
> + XFS_SB_CRC_OFF },
> { TYP_SYMLINK, "symlink", handle_struct, symlink_crc_hfld,
> - &xfs_symlink_buf_ops },
> - { TYP_TEXT, "text", handle_text, NULL, NULL },
> + &xfs_symlink_buf_ops, XFS_SYMLINK_CRC_OFF },
> + { TYP_TEXT, "text", handle_text, NULL, NULL, TYP_NO_CRC_OFF },
> { TYP_FINOBT, "finobt", handle_struct, inobt_crc_hfld,
> - &xfs_inobt_buf_ops },
> + &xfs_inobt_buf_ops, XFS_BTREE_SBLOCK_CRC_OFF },
> { TYP_NONE, NULL }
> };
>
> static const typ_t __typtab_spcrc[] = {
> - { TYP_AGF, "agf", handle_struct, agf_hfld, &xfs_agf_buf_ops },
> - { TYP_AGFL, "agfl", handle_struct, agfl_crc_hfld, &xfs_agfl_buf_ops },
> - { TYP_AGI, "agi", handle_struct, agi_hfld, &xfs_agi_buf_ops },
> + { TYP_AGF, "agf", handle_struct, agf_hfld, &xfs_agf_buf_ops,
> + XFS_AGF_CRC_OFF },
> + { TYP_AGFL, "agfl", handle_struct, agfl_crc_hfld, &xfs_agfl_buf_ops ,
> + XFS_AGFL_CRC_OFF },
> + { TYP_AGI, "agi", handle_struct, agi_hfld, &xfs_agi_buf_ops ,
> + XFS_AGI_CRC_OFF },
> { TYP_ATTR, "attr3", handle_struct, attr3_hfld,
> - &xfs_attr3_db_buf_ops },
> + &xfs_attr3_db_buf_ops, TYP_NO_CRC_OFF },
> { TYP_BMAPBTA, "bmapbta", handle_struct, bmapbta_crc_hfld,
> - &xfs_bmbt_buf_ops },
> + &xfs_bmbt_buf_ops, XFS_BTREE_LBLOCK_CRC_OFF },
> { TYP_BMAPBTD, "bmapbtd", handle_struct, bmapbtd_crc_hfld,
> - &xfs_bmbt_buf_ops },
> + &xfs_bmbt_buf_ops, XFS_BTREE_LBLOCK_CRC_OFF },
> { TYP_BNOBT, "bnobt", handle_struct, bnobt_crc_hfld,
> - &xfs_allocbt_buf_ops },
> + &xfs_allocbt_buf_ops, XFS_BTREE_SBLOCK_CRC_OFF },
> { TYP_CNTBT, "cntbt", handle_struct, cntbt_crc_hfld,
> - &xfs_allocbt_buf_ops },
> - { TYP_DATA, "data", handle_block, NULL, NULL },
> + &xfs_allocbt_buf_ops, XFS_BTREE_SBLOCK_CRC_OFF },
> + { TYP_DATA, "data", handle_block, NULL, NULL, TYP_NO_CRC_OFF },
> { TYP_DIR2, "dir3", handle_struct, dir3_hfld,
> - &xfs_dir3_db_buf_ops },
> + &xfs_dir3_db_buf_ops, TYP_NO_CRC_OFF },
> { TYP_DQBLK, "dqblk", handle_struct, dqblk_hfld,
> - &xfs_dquot_buf_ops },
> + &xfs_dquot_buf_ops, TYP_NO_CRC_OFF },
> { TYP_INOBT, "inobt", handle_struct, inobt_spcrc_hfld,
> - &xfs_inobt_buf_ops },
> - { TYP_INODATA, "inodata", NULL, NULL, NULL },
> + &xfs_inobt_buf_ops, XFS_BTREE_SBLOCK_CRC_OFF },
> + { TYP_INODATA, "inodata", NULL, NULL, NULL, TYP_NO_CRC_OFF },
> { TYP_INODE, "inode", handle_struct, inode_crc_hfld,
> - &xfs_inode_buf_ops },
> - { TYP_LOG, "log", NULL, NULL, NULL },
> - { TYP_RTBITMAP, "rtbitmap", NULL, NULL, NULL },
> - { TYP_RTSUMMARY, "rtsummary", NULL, NULL, NULL },
> - { TYP_SB, "sb", handle_struct, sb_hfld, &xfs_sb_buf_ops },
> + &xfs_inode_buf_ops, TYP_NO_CRC_OFF },
> + { TYP_LOG, "log", NULL, NULL, NULL, TYP_NO_CRC_OFF },
> + { TYP_RTBITMAP, "rtbitmap", NULL, NULL, NULL, TYP_NO_CRC_OFF },
> + { TYP_RTSUMMARY, "rtsummary", NULL, NULL, NULL, TYP_NO_CRC_OFF },
> + { TYP_SB, "sb", handle_struct, sb_hfld, &xfs_sb_buf_ops,
> + XFS_SB_CRC_OFF },
> { TYP_SYMLINK, "symlink", handle_struct, symlink_crc_hfld,
> - &xfs_symlink_buf_ops },
> - { TYP_TEXT, "text", handle_text, NULL, NULL },
> + &xfs_symlink_buf_ops, XFS_SYMLINK_CRC_OFF },
> + { TYP_TEXT, "text", handle_text, NULL, NULL, TYP_NO_CRC_OFF },
> { TYP_FINOBT, "finobt", handle_struct, inobt_crc_hfld,
> - &xfs_inobt_buf_ops },
> + &xfs_inobt_buf_ops, XFS_BTREE_SBLOCK_CRC_OFF },
> { TYP_NONE, NULL }
> };
>
> diff --git a/db/type.h b/db/type.h
> index d9583e5..e954a68 100644
> --- a/db/type.h
> +++ b/db/type.h
> @@ -43,6 +43,8 @@ typedef struct typ
> pfunc_t pfunc;
> const struct field *fields;
> const struct xfs_buf_ops *bops;
> + unsigned long crc_off;
> +#define TYP_NO_CRC_OFF (-1UL)
> } typ_t;
> extern const typ_t *typtab, *cur_typ;
>
> diff --git a/db/write.c b/db/write.c
> index 9f5b423..a922e16 100644
> --- a/db/write.c
> +++ b/db/write.c
> @@ -79,7 +79,10 @@ write_help(void)
> " String mode: 'write \"This_is_a_filename\" - write null terminated string.\n"
> "\n"
> " In data mode type 'write' by itself for a list of specific commands.\n\n"
> -" Specifying the -c option will allow writes of invalid (corrupt) data.\n\n"
> +" Specifying the -c option will allow writes of invalid (corrupt) data with\n"
> +" an invalid CRC. Specifying the -d option will allow writes of invalid data,\n"
> +" but still recalculate the CRC so we are forced to check and detect the\n"
> +" invalid data appropriately.\n\n"
> ));
>
> }
> @@ -92,7 +95,8 @@ write_f(
> pfunc_t pf;
> extern char *progname;
> int c;
> - int corrupt = 0; /* Allow write of corrupt data; skip verification */
> + bool corrupt = false; /* Allow write of bad data w/ invalid CRC */
> + bool invalid_data = false; /* Allow write of bad data w/ valid CRC */
> struct xfs_buf_ops nowrite_ops;
> const struct xfs_buf_ops *stashed_ops = NULL;
>
> @@ -114,10 +118,13 @@ write_f(
> return 0;
> }
>
> - while ((c = getopt(argc, argv, "c")) != EOF) {
> + while ((c = getopt(argc, argv, "cd")) != EOF) {
> switch (c) {
> case 'c':
> - corrupt = 1;
> + corrupt = true;
> + break;
> + case 'd':
> + invalid_data = true;
> break;
> default:
> dbprintf(_("bad option for write command\n"));
> @@ -125,22 +132,43 @@ write_f(
> }
> }
>
> + if (corrupt && invalid_data) {
> + dbprintf(_("Cannot specify both -c and -d options\n"));
> + return 0;
> + }
> +
> + if (invalid_data && iocur_top->typ->crc_off == TYP_NO_CRC_OFF) {
> + dbprintf(_("Cannot recalculate CRCs on this type of object\n"));
> + return 0;
> + }
> +
> argc -= optind;
> argv += optind;
>
> - if (iocur_top->bp->b_ops && corrupt) {
> - /* Temporarily remove write verifier to write bad data */
> - stashed_ops = iocur_top->bp->b_ops;
> - nowrite_ops.verify_read = stashed_ops->verify_read;
> + /* If we don't have to juggle verifiers, then just issue the write */
This is a little confusing - we know what juggling verifiers means but
future readers may not have that fresh in mind. ;)
/* No verifier, or standard verifier paths; just write it out and return */
> + if (!iocur_top->bp->b_ops ||
> + !(corrupt || invalid_data)) {
> + (*pf)(DB_WRITE, cur_typ->fields, argc, argv);
> + return 0;
> + }
> +
> +
> + /* Temporarily remove write verifier to write bad data */
> + stashed_ops = iocur_top->bp->b_ops;
> + nowrite_ops.verify_read = stashed_ops->verify_read;
> + iocur_top->bp->b_ops = &nowrite_ops;
I'm regretting my name choice of "nowrite_ops" ...
> +
> + if (corrupt) {
> nowrite_ops.verify_write = xfs_dummy_verify;
> - iocur_top->bp->b_ops = &nowrite_ops;
> - dbprintf(_("Allowing write of corrupted data\n"));
> + dbprintf(_("Allowing write of corrupted data and bad CRC\n"));
> + } else {
Maybe a helpful/redundant comment about /* invalid_data */ alongside } else { ?
> + nowrite_ops.verify_write = xfs_verify_recalc_crc;
yeah, the point of "nowrite_ops" was to indicate no write verifier present;
now you add a write verifier :)
s/nowrite_ops/new_ops/ or something might be better now, but I suppose
that could come in a prior or later patch to not clutter this one up...
> + dbprintf(_("Allowing write of corrupted data with good CRC\n"));
> }
>
> (*pf)(DB_WRITE, cur_typ->fields, argc, argv);
>
> - if (stashed_ops)
> - iocur_top->bp->b_ops = stashed_ops;
> + iocur_top->bp->b_ops = stashed_ops;
>
> return 0;
> }
>
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