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Constify structures containing function pointers
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The PaX team modified the kernel's modpost to report writeable function
pointers as section mismatches because they are potential exploit
targets. We could ignore the warnings, but their presence can obscure
actual issues. Proper const correctness can also catch programming
mistakes.

Building the kernel modules against a PaX/GrSecurity patched Linux 3.4.2
kernel reports 133 section mismatches prior to this patch. This patch
eliminates 130 of them. The quantity of writeable function pointers
eliminated by constifying each structure is as follows:

vdev_opts_t             52
zil_replay_func_t       24
zio_compress_info_t     24
zio_checksum_info_t     9
space_map_ops_t         7
arc_byteswap_func_t     5

The remaining 3 writeable function pointers cannot be addressed by this
patch. 2 of them are in zpl_fs_type. The kernel's sget function requires
that this be non-const. The final writeable function pointer is created
by SPL_SHRINKER_DECLARE. The kernel's set_shrinker() and
remove_shrinker() functions also require that this be non-const.

Signed-off-by: Richard Yao <ryao@cs.stonybrook.edu>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #1300
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@ryao @behlendorf
ryao authored and behlendorf committed Mar 4, 2013
1 parent c38367c commit b01615d
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Showing 13 changed files with 59 additions and 59 deletions.
12 changes: 6 additions & 6 deletions cmd/ztest/ztest.c
View file
Expand Up @@ -1792,19 +1792,19 @@ ztest_replay_setattr(ztest_ds_t *zd, lr_setattr_t *lr, boolean_t byteswap)
return (0);
}

zil_replay_func_t *ztest_replay_vector[TX_MAX_TYPE] = {
zil_replay_func_t ztest_replay_vector[TX_MAX_TYPE] = {
NULL, /* 0 no such transaction type */
(zil_replay_func_t *)ztest_replay_create, /* TX_CREATE */
(zil_replay_func_t)ztest_replay_create, /* TX_CREATE */
NULL, /* TX_MKDIR */
NULL, /* TX_MKXATTR */
NULL, /* TX_SYMLINK */
(zil_replay_func_t *)ztest_replay_remove, /* TX_REMOVE */
(zil_replay_func_t)ztest_replay_remove, /* TX_REMOVE */
NULL, /* TX_RMDIR */
NULL, /* TX_LINK */
NULL, /* TX_RENAME */
(zil_replay_func_t *)ztest_replay_write, /* TX_WRITE */
(zil_replay_func_t *)ztest_replay_truncate, /* TX_TRUNCATE */
(zil_replay_func_t *)ztest_replay_setattr, /* TX_SETATTR */
(zil_replay_func_t)ztest_replay_write, /* TX_WRITE */
(zil_replay_func_t)ztest_replay_truncate, /* TX_TRUNCATE */
(zil_replay_func_t)ztest_replay_setattr, /* TX_SETATTR */
NULL, /* TX_ACL */
NULL, /* TX_CREATE_ACL */
NULL, /* TX_CREATE_ATTR */
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6 changes: 3 additions & 3 deletions include/sys/dmu.h
View file
Expand Up @@ -641,16 +641,16 @@ typedef struct dmu_object_info {
uint64_t doi_fill_count; /* number of non-empty blocks */
} dmu_object_info_t;

typedef void arc_byteswap_func_t(void *buf, size_t size);
typedef void (*const arc_byteswap_func_t)(void *buf, size_t size);

typedef struct dmu_object_type_info {
dmu_object_byteswap_t ot_byteswap;
boolean_t ot_metadata;
char *ot_name;
} dmu_object_type_info_t;

typedef struct dmu_object_byteswap_info {
arc_byteswap_func_t *ob_func;
typedef const struct dmu_object_byteswap_info {
arc_byteswap_func_t ob_func;
char *ob_name;
} dmu_object_byteswap_info_t;

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2 changes: 1 addition & 1 deletion include/sys/space_map.h
View file
Expand Up @@ -33,7 +33,7 @@
extern "C" {
#endif

typedef struct space_map_ops space_map_ops_t;
typedef const struct space_map_ops space_map_ops_t;

typedef struct space_map {
avl_tree_t sm_root; /* AVL tree of map segments */
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2 changes: 1 addition & 1 deletion include/sys/vdev_impl.h
View file
Expand Up @@ -67,7 +67,7 @@ typedef void vdev_state_change_func_t(vdev_t *vd, int, int);
typedef void vdev_hold_func_t(vdev_t *vd);
typedef void vdev_rele_func_t(vdev_t *vd);

typedef struct vdev_ops {
typedef const struct vdev_ops {
vdev_open_func_t *vdev_op_open;
vdev_close_func_t *vdev_op_close;
vdev_asize_func_t *vdev_op_asize;
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2 changes: 1 addition & 1 deletion include/sys/zfs_znode.h
View file
Expand Up @@ -371,7 +371,7 @@ extern void zfs_unmap_page(page_t *, caddr_t);
#endif /* HAVE_UIO_RW */

extern zil_get_data_t zfs_get_data;
extern zil_replay_func_t *zfs_replay_vector[TX_MAX_TYPE];
extern zil_replay_func_t zfs_replay_vector[TX_MAX_TYPE];
extern int zfsfstype;

#endif /* _KERNEL */
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4 changes: 2 additions & 2 deletions include/sys/zil.h
View file
Expand Up @@ -436,7 +436,7 @@ typedef int zil_parse_blk_func_t(zilog_t *zilog, blkptr_t *bp, void *arg,
uint64_t txg);
typedef int zil_parse_lr_func_t(zilog_t *zilog, lr_t *lr, void *arg,
uint64_t txg);
typedef int zil_replay_func_t(void *, char *, boolean_t);
typedef int (*const zil_replay_func_t)(void *, char *, boolean_t);
typedef int zil_get_data_t(void *arg, lr_write_t *lr, char *dbuf, zio_t *zio);

extern int zil_parse(zilog_t *zilog, zil_parse_blk_func_t *parse_blk_func,
Expand All @@ -452,7 +452,7 @@ extern zilog_t *zil_open(objset_t *os, zil_get_data_t *get_data);
extern void zil_close(zilog_t *zilog);

extern void zil_replay(objset_t *os, void *arg,
zil_replay_func_t *replay_func[TX_MAX_TYPE]);
zil_replay_func_t replay_func[TX_MAX_TYPE]);
extern boolean_t zil_replaying(zilog_t *zilog, dmu_tx_t *tx);
extern void zil_destroy(zilog_t *zilog, boolean_t keep_first);
extern void zil_destroy_sync(zilog_t *zilog, dmu_tx_t *tx);
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2 changes: 1 addition & 1 deletion include/sys/zio_checksum.h
View file
Expand Up @@ -39,7 +39,7 @@ typedef void zio_checksum_t(const void *data, uint64_t size, zio_cksum_t *zcp);
/*
* Information about each checksum function.
*/
typedef struct zio_checksum_info {
typedef const struct zio_checksum_info {
zio_checksum_t *ci_func[2]; /* checksum function for each byteorder */
int ci_correctable; /* number of correctable bits */
int ci_eck; /* uses zio embedded checksum? */
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2 changes: 1 addition & 1 deletion include/sys/zio_compress.h
View file
Expand Up @@ -44,7 +44,7 @@ typedef int zio_decompress_func_t(void *src, void *dst,
/*
* Information about each compression function.
*/
typedef struct zio_compress_info {
typedef const struct zio_compress_info {
zio_compress_func_t *ci_compress; /* compression function */
zio_decompress_func_t *ci_decompress; /* decompression function */
int ci_level; /* level parameter */
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8 changes: 4 additions & 4 deletions module/zfs/arc.c
View file
Expand Up @@ -2802,10 +2802,10 @@ arc_read_done(zio_t *zio)
if (BP_SHOULD_BYTESWAP(zio->io_bp) && zio->io_error == 0) {
dmu_object_byteswap_t bswap =
DMU_OT_BYTESWAP(BP_GET_TYPE(zio->io_bp));
arc_byteswap_func_t *func = BP_GET_LEVEL(zio->io_bp) > 0 ?
byteswap_uint64_array :
dmu_ot_byteswap[bswap].ob_func;
func(buf->b_data, hdr->b_size);
if (BP_GET_LEVEL(zio->io_bp) > 0)
byteswap_uint64_array(buf->b_data, hdr->b_size);
else
dmu_ot_byteswap[bswap].ob_func(buf->b_data, hdr->b_size);
}

arc_cksum_compute(buf, B_FALSE);
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2 changes: 1 addition & 1 deletion module/zfs/sa.c
View file
Expand Up @@ -136,7 +136,7 @@ static int sa_modify_attrs(sa_handle_t *hdl, sa_attr_type_t newattr,
sa_data_op_t action, sa_data_locator_t *locator, void *datastart,
uint16_t buflen, dmu_tx_t *tx);

arc_byteswap_func_t *sa_bswap_table[] = {
arc_byteswap_func_t sa_bswap_table[] = {
byteswap_uint64_array,
byteswap_uint32_array,
byteswap_uint16_array,
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44 changes: 22 additions & 22 deletions module/zfs/zfs_replay.c
View file
Expand Up @@ -910,26 +910,26 @@ zfs_replay_acl(zfs_sb_t *zsb, lr_acl_t *lr, boolean_t byteswap)
/*
* Callback vectors for replaying records
*/
zil_replay_func_t *zfs_replay_vector[TX_MAX_TYPE] = {
(zil_replay_func_t *)zfs_replay_error, /* no such type */
(zil_replay_func_t *)zfs_replay_create, /* TX_CREATE */
(zil_replay_func_t *)zfs_replay_create, /* TX_MKDIR */
(zil_replay_func_t *)zfs_replay_create, /* TX_MKXATTR */
(zil_replay_func_t *)zfs_replay_create, /* TX_SYMLINK */
(zil_replay_func_t *)zfs_replay_remove, /* TX_REMOVE */
(zil_replay_func_t *)zfs_replay_remove, /* TX_RMDIR */
(zil_replay_func_t *)zfs_replay_link, /* TX_LINK */
(zil_replay_func_t *)zfs_replay_rename, /* TX_RENAME */
(zil_replay_func_t *)zfs_replay_write, /* TX_WRITE */
(zil_replay_func_t *)zfs_replay_truncate, /* TX_TRUNCATE */
(zil_replay_func_t *)zfs_replay_setattr, /* TX_SETATTR */
(zil_replay_func_t *)zfs_replay_acl_v0, /* TX_ACL_V0 */
(zil_replay_func_t *)zfs_replay_acl, /* TX_ACL */
(zil_replay_func_t *)zfs_replay_create_acl, /* TX_CREATE_ACL */
(zil_replay_func_t *)zfs_replay_create, /* TX_CREATE_ATTR */
(zil_replay_func_t *)zfs_replay_create_acl, /* TX_CREATE_ACL_ATTR */
(zil_replay_func_t *)zfs_replay_create_acl, /* TX_MKDIR_ACL */
(zil_replay_func_t *)zfs_replay_create, /* TX_MKDIR_ATTR */
(zil_replay_func_t *)zfs_replay_create_acl, /* TX_MKDIR_ACL_ATTR */
(zil_replay_func_t *)zfs_replay_write2, /* TX_WRITE2 */
zil_replay_func_t zfs_replay_vector[TX_MAX_TYPE] = {
(zil_replay_func_t)zfs_replay_error, /* no such type */
(zil_replay_func_t)zfs_replay_create, /* TX_CREATE */
(zil_replay_func_t)zfs_replay_create, /* TX_MKDIR */
(zil_replay_func_t)zfs_replay_create, /* TX_MKXATTR */
(zil_replay_func_t)zfs_replay_create, /* TX_SYMLINK */
(zil_replay_func_t)zfs_replay_remove, /* TX_REMOVE */
(zil_replay_func_t)zfs_replay_remove, /* TX_RMDIR */
(zil_replay_func_t)zfs_replay_link, /* TX_LINK */
(zil_replay_func_t)zfs_replay_rename, /* TX_RENAME */
(zil_replay_func_t)zfs_replay_write, /* TX_WRITE */
(zil_replay_func_t)zfs_replay_truncate, /* TX_TRUNCATE */
(zil_replay_func_t)zfs_replay_setattr, /* TX_SETATTR */
(zil_replay_func_t)zfs_replay_acl_v0, /* TX_ACL_V0 */
(zil_replay_func_t)zfs_replay_acl, /* TX_ACL */
(zil_replay_func_t)zfs_replay_create_acl, /* TX_CREATE_ACL */
(zil_replay_func_t)zfs_replay_create, /* TX_CREATE_ATTR */
(zil_replay_func_t)zfs_replay_create_acl, /* TX_CREATE_ACL_ATTR */
(zil_replay_func_t)zfs_replay_create_acl, /* TX_MKDIR_ACL */
(zil_replay_func_t)zfs_replay_create, /* TX_MKDIR_ATTR */
(zil_replay_func_t)zfs_replay_create_acl, /* TX_MKDIR_ACL_ATTR */
(zil_replay_func_t)zfs_replay_write2, /* TX_WRITE2 */
};
4 changes: 2 additions & 2 deletions module/zfs/zil.c
View file
Expand Up @@ -1956,7 +1956,7 @@ zil_resume(zilog_t *zilog)
}

typedef struct zil_replay_arg {
zil_replay_func_t **zr_replay;
zil_replay_func_t *zr_replay;
void *zr_arg;
boolean_t zr_byteswap;
char *zr_lr;
Expand Down Expand Up @@ -2075,7 +2075,7 @@ zil_incr_blks(zilog_t *zilog, blkptr_t *bp, void *arg, uint64_t claim_txg)
* If this dataset has a non-empty intent log, replay it and destroy it.
*/
void
zil_replay(objset_t *os, void *arg, zil_replay_func_t *replay_func[TX_MAX_TYPE])
zil_replay(objset_t *os, void *arg, zil_replay_func_t replay_func[TX_MAX_TYPE])
{
zilog_t *zilog = dmu_objset_zil(os);
const zil_header_t *zh = zilog->zl_header;
Expand Down
28 changes: 14 additions & 14 deletions module/zfs/zvol.c
View file
Expand Up @@ -453,20 +453,20 @@ zvol_replay_err(zvol_state_t *zv, lr_t *lr, boolean_t byteswap)
* Callback vectors for replaying records.
* Only TX_WRITE is needed for zvol.
*/
zil_replay_func_t *zvol_replay_vector[TX_MAX_TYPE] = {
(zil_replay_func_t *)zvol_replay_err, /* no such transaction type */
(zil_replay_func_t *)zvol_replay_err, /* TX_CREATE */
(zil_replay_func_t *)zvol_replay_err, /* TX_MKDIR */
(zil_replay_func_t *)zvol_replay_err, /* TX_MKXATTR */
(zil_replay_func_t *)zvol_replay_err, /* TX_SYMLINK */
(zil_replay_func_t *)zvol_replay_err, /* TX_REMOVE */
(zil_replay_func_t *)zvol_replay_err, /* TX_RMDIR */
(zil_replay_func_t *)zvol_replay_err, /* TX_LINK */
(zil_replay_func_t *)zvol_replay_err, /* TX_RENAME */
(zil_replay_func_t *)zvol_replay_write, /* TX_WRITE */
(zil_replay_func_t *)zvol_replay_err, /* TX_TRUNCATE */
(zil_replay_func_t *)zvol_replay_err, /* TX_SETATTR */
(zil_replay_func_t *)zvol_replay_err, /* TX_ACL */
zil_replay_func_t zvol_replay_vector[TX_MAX_TYPE] = {
(zil_replay_func_t)zvol_replay_err, /* no such transaction type */
(zil_replay_func_t)zvol_replay_err, /* TX_CREATE */
(zil_replay_func_t)zvol_replay_err, /* TX_MKDIR */
(zil_replay_func_t)zvol_replay_err, /* TX_MKXATTR */
(zil_replay_func_t)zvol_replay_err, /* TX_SYMLINK */
(zil_replay_func_t)zvol_replay_err, /* TX_REMOVE */
(zil_replay_func_t)zvol_replay_err, /* TX_RMDIR */
(zil_replay_func_t)zvol_replay_err, /* TX_LINK */
(zil_replay_func_t)zvol_replay_err, /* TX_RENAME */
(zil_replay_func_t)zvol_replay_write, /* TX_WRITE */
(zil_replay_func_t)zvol_replay_err, /* TX_TRUNCATE */
(zil_replay_func_t)zvol_replay_err, /* TX_SETATTR */
(zil_replay_func_t)zvol_replay_err, /* TX_ACL */
};

/*
Expand Down

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