Patchwork UBIFS: add crypto lookup field to tree node cache

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Submitter Joel Reardon
Date May 11, 2012, 11:24 a.m.
Message ID <alpine.DEB.2.00.1205111323010.17715@eristoteles.iwoars.net>
Download mbox | patch
Permalink /patch/158489/
State New
Headers show

Comments

Joel Reardon - May 11, 2012, 11:24 a.m.
This patch adds a new field to the TNC's zbranch and allows it to be set when
a node is added or replaced. The field is called 'crypto_lookup' and it refers
to a location in the key storage area---a pointer to a key that is used to
encrypt/decrypt the data node. It can be set to 0 or a negative number when it
is not being used. When a new node is added, this value is passed and set
When a node is replace, the old value is replaced with the new value.

These values will be used in future patchs. Replacing a
crypto_lookup value will also mark the old value as deleted and the new value
as used; adding a new node will mark the value as used. Additionally, deleting
or removing TNC nodes will mark the values as deleted.

TNC's crypto_lookup values are not stored on disk. They will be stored in the
data
node's header. Therefore, if a crypto_lookup value is invalid (but a valid one
is to be expected and needs to be used) then a function will be added that
reads the data node to
obtain the value. Additionally, when a data node is ever read, the
crypto_lookup position that is read will be set in the corresponding zbranch.

The values are not stored on disk to avoid having different on-disk formats of
the the ubifs_branch structure.

Signed-off-by: Joel Reardon <reardonj@inf.ethz.ch>
---
 fs/ubifs/gc.c       |    2 +-
 fs/ubifs/journal.c  |   24 ++++++++++++------------
 fs/ubifs/replay.c   |    2 +-
 fs/ubifs/tnc.c      |   11 +++++++++--
 fs/ubifs/tnc_misc.c |    1 +
 fs/ubifs/ubifs.h    |    7 +++++--
 6 files changed, 29 insertions(+), 18 deletions(-)
Artem Bityutskiy - May 14, 2012, 1:21 p.m.
On Fri, 2012-05-11 at 13:24 +0200, Joel Reardon wrote:
>  struct ubifs_zbranch {
>  	union ubifs_key key;
> @@ -751,6 +752,7 @@ struct ubifs_zbranch {
>  	int lnum;
>  	int offs;
>  	int len;
> +	long long crypto_lookup;
>  };

Why is it "long long" which is 64 bit? What will it contain? Could we
make it unsigned int - we'd waste less RAM then - remember that we
allocate a lot of these structures.
Joel Reardon - May 14, 2012, 5:20 p.m.
The long long is divided as follows:
32 bits for the (KSA-relative) LEB number, 32 bits for the offset in the
leb where the key is found. So its the same as the lnum/offs for the
current one. Theres substancial compression though, that is available,
since theres likely not more than 2^^32 LEBS for the KSA and the number of
bits needed for key offset is LEB_SHIFT - 4.

Is 32 bits sufficient to address all keys:
one key per datanode means 4096 * 2^32 = 2^44, so only 16 TB available
for 32 bit key addresses.

Though there is similar waste for lnum/offs as well. Perhaps zbranches can
be stored as a u8[] and demarshalled with bit-op macros when needed for
computations.

Joel Reardon




On Mon, 14 May 2012, Artem Bityutskiy wrote:

> On Fri, 2012-05-11 at 13:24 +0200, Joel Reardon wrote:
> >  struct ubifs_zbranch {
> >  	union ubifs_key key;
> > @@ -751,6 +752,7 @@ struct ubifs_zbranch {
> >  	int lnum;
> >  	int offs;
> >  	int len;
> > +	long long crypto_lookup;
> >  };
>
> Why is it "long long" which is 64 bit? What will it contain? Could we
> make it unsigned int - we'd waste less RAM then - remember that we
> allocate a lot of these structures.
>
> --
> Best Regards,
> Artem Bityutskiy
>
Artem Bityutskiy - May 14, 2012, 6:28 p.m.
On Mon, 2012-05-14 at 19:20 +0200, Joel Reardon wrote:
> The long long is divided as follows:
> 32 bits for the (KSA-relative) LEB number, 32 bits for the offset in the
> leb where the key is found. So its the same as the lnum/offs for the
> current one. Theres substancial compression though, that is available,
> since theres likely not more than 2^^32 LEBS for the KSA and the number of
> bits needed for key offset is LEB_SHIFT - 4.
> 
> Is 32 bits sufficient to address all keys:
> one key per datanode means 4096 * 2^32 = 2^44, so only 16 TB available
> for 32 bit key addresses.
> 
> Though there is similar waste for lnum/offs as well. Perhaps zbranches can
> be stored as a u8[] and demarshalled with bit-op macros when needed for
> computations.

OK, thanks for explanation. Why not to then store 2x32-bit fields
instead, which is consistent with the current style? Why "long long"?
Joel Reardon - May 14, 2012, 6:45 p.m.
I use this because I figured it should be abstracted in functions that
have these values, but don't need to know about the internal structure.
From the view of all UBIFS components (except the new keymap), two values
have no more meaning than one, its all just some value the keymap gives
out and returns the same key on read_key.

cheers,
Joel Reardon

On Mon, 14 May 2012, Artem Bityutskiy wrote:

> On Mon, 2012-05-14 at 19:20 +0200, Joel Reardon wrote:
> > The long long is divided as follows:
> > 32 bits for the (KSA-relative) LEB number, 32 bits for the offset in the
> > leb where the key is found. So its the same as the lnum/offs for the
> > current one. Theres substancial compression though, that is available,
> > since theres likely not more than 2^^32 LEBS for the KSA and the number of
> > bits needed for key offset is LEB_SHIFT - 4.
> >
> > Is 32 bits sufficient to address all keys:
> > one key per datanode means 4096 * 2^32 = 2^44, so only 16 TB available
> > for 32 bit key addresses.
> >
> > Though there is similar waste for lnum/offs as well. Perhaps zbranches can
> > be stored as a u8[] and demarshalled with bit-op macros when needed for
> > computations.
>
> OK, thanks for explanation. Why not to then store 2x32-bit fields
> instead, which is consistent with the current style? Why "long long"?
>
> --
> Best Regards,
> Artem Bityutskiy
>
Artem Bityutskiy - May 14, 2012, 7:14 p.m.
On Mon, 2012-05-14 at 20:45 +0200, Joel Reardon wrote:
> I use this because I figured it should be abstracted in functions that
> have these values, but don't need to know about the internal structure.
> From the view of all UBIFS components (except the new keymap), two values
> have no more meaning than one, its all just some value the keymap gives
> out and returns the same key on read_key.

Well, dunno, OK, let's see - we can changes this later if needed. I'll
apply this patch tomorrow.
Artem Bityutskiy - May 15, 2012, 6:21 a.m.
On Fri, 2012-05-11 at 13:24 +0200, Joel Reardon wrote:
> This patch adds a new field to the TNC's zbranch and allows it to be set when
> a node is added or replaced. The field is called 'crypto_lookup' and it refers
> to a location in the key storage area---a pointer to a key that is used to
> encrypt/decrypt the data node. It can be set to 0 or a negative number when it
> is not being used. When a new node is added, this value is passed and set
> When a node is replace, the old value is replaced with the new value.
> 
> These values will be used in future patchs. Replacing a
> crypto_lookup value will also mark the old value as deleted and the new value
> as used; adding a new node will mark the value as used. Additionally, deleting
> or removing TNC nodes will mark the values as deleted.
> 
> TNC's crypto_lookup values are not stored on disk. They will be stored in the
> data
> node's header. Therefore, if a crypto_lookup value is invalid (but a valid one
> is to be expected and needs to be used) then a function will be added that
> reads the data node to
> obtain the value. Additionally, when a data node is ever read, the
> crypto_lookup position that is read will be set in the corresponding zbranch.
> 
> The values are not stored on disk to avoid having different on-disk formats of
> the the ubifs_branch structure.
> 
> Signed-off-by: Joel Reardon <reardonj@inf.ethz.ch>

Pushed to the "joel" branch, thanks!

Patch

diff --git a/fs/ubifs/gc.c b/fs/ubifs/gc.c
index ded29f6..528ed58 100644
--- a/fs/ubifs/gc.c
+++ b/fs/ubifs/gc.c
@@ -330,7 +330,7 @@  static int move_node(struct ubifs_info *c, struct ubifs_scan_leb *sleb,

 	err = ubifs_tnc_replace(c, &snod->key, sleb->lnum,
 				snod->offs, new_lnum, new_offs,
-				snod->len);
+				snod->len, 0);
 	list_del(&snod->list);
 	kfree(snod);
 	return err;
diff --git a/fs/ubifs/journal.c b/fs/ubifs/journal.c
index 57c4d2f..f3eb13c 100644
--- a/fs/ubifs/journal.c
+++ b/fs/ubifs/journal.c
@@ -646,13 +646,13 @@  int ubifs_jnl_update(struct ubifs_info *c, const struct inode *dir,
 	 */
 	ino_key_init(c, &ino_key, inode->i_ino);
 	ino_offs = dent_offs + aligned_dlen;
-	err = ubifs_tnc_add(c, &ino_key, lnum, ino_offs, ilen);
+	err = ubifs_tnc_add(c, &ino_key, lnum, ino_offs, ilen, 0);
 	if (err)
 		goto out_ro;

 	ino_key_init(c, &ino_key, dir->i_ino);
 	ino_offs += aligned_ilen;
-	err = ubifs_tnc_add(c, &ino_key, lnum, ino_offs, UBIFS_INO_NODE_SZ);
+	err = ubifs_tnc_add(c, &ino_key, lnum, ino_offs, UBIFS_INO_NODE_SZ, 0);
 	if (err)
 		goto out_ro;

@@ -747,7 +747,7 @@  int ubifs_jnl_write_data(struct ubifs_info *c, const struct inode *inode,
 	ubifs_wbuf_add_ino_nolock(&c->jheads[DATAHD].wbuf, key_inum(c, key));
 	release_head(c, DATAHD);

-	err = ubifs_tnc_add(c, key, lnum, offs, dlen);
+	err = ubifs_tnc_add(c, key, lnum, offs, dlen, 0);
 	if (err)
 		goto out_ro;

@@ -825,7 +825,7 @@  int ubifs_jnl_write_inode(struct ubifs_info *c, const struct inode *inode)
 		union ubifs_key key;

 		ino_key_init(c, &key, inode->i_ino);
-		err = ubifs_tnc_add(c, &key, lnum, offs, len);
+		err = ubifs_tnc_add(c, &key, lnum, offs, len, 0);
 	}
 	if (err)
 		goto out_ro;
@@ -1048,21 +1048,21 @@  int ubifs_jnl_rename(struct ubifs_info *c, const struct inode *old_dir,
 	offs += aligned_dlen1 + aligned_dlen2;
 	if (new_inode) {
 		ino_key_init(c, &key, new_inode->i_ino);
-		err = ubifs_tnc_add(c, &key, lnum, offs, ilen);
+		err = ubifs_tnc_add(c, &key, lnum, offs, ilen, 0);
 		if (err)
 			goto out_ro;
 		offs += ALIGN(ilen, 8);
 	}

 	ino_key_init(c, &key, old_dir->i_ino);
-	err = ubifs_tnc_add(c, &key, lnum, offs, plen);
+	err = ubifs_tnc_add(c, &key, lnum, offs, plen, 0);
 	if (err)
 		goto out_ro;

 	if (old_dir != new_dir) {
 		offs += ALIGN(plen, 8);
 		ino_key_init(c, &key, new_dir->i_ino);
-		err = ubifs_tnc_add(c, &key, lnum, offs, plen);
+		err = ubifs_tnc_add(c, &key, lnum, offs, plen, 0);
 		if (err)
 			goto out_ro;
 	}
@@ -1226,13 +1226,13 @@  int ubifs_jnl_truncate(struct ubifs_info *c, const struct inode *inode,

 	if (dlen) {
 		sz = offs + UBIFS_INO_NODE_SZ + UBIFS_TRUN_NODE_SZ;
-		err = ubifs_tnc_add(c, &key, lnum, sz, dlen);
+		err = ubifs_tnc_add(c, &key, lnum, sz, dlen, 0);
 		if (err)
 			goto out_ro;
 	}

 	ino_key_init(c, &key, inum);
-	err = ubifs_tnc_add(c, &key, lnum, offs, UBIFS_INO_NODE_SZ);
+	err = ubifs_tnc_add(c, &key, lnum, offs, UBIFS_INO_NODE_SZ, 0);
 	if (err)
 		goto out_ro;

@@ -1367,7 +1367,7 @@  int ubifs_jnl_delete_xattr(struct ubifs_info *c, const struct inode *host,

 	/* And update TNC with the new host inode position */
 	ino_key_init(c, &key1, host->i_ino);
-	err = ubifs_tnc_add(c, &key1, lnum, xent_offs + len - hlen, hlen);
+	err = ubifs_tnc_add(c, &key1, lnum, xent_offs + len - hlen, hlen, 0);
 	if (err)
 		goto out_ro;

@@ -1440,12 +1440,12 @@  int ubifs_jnl_change_xattr(struct ubifs_info *c, const struct inode *inode,
 		goto out_ro;

 	ino_key_init(c, &key, host->i_ino);
-	err = ubifs_tnc_add(c, &key, lnum, offs, len1);
+	err = ubifs_tnc_add(c, &key, lnum, offs, len1, 0);
 	if (err)
 		goto out_ro;

 	ino_key_init(c, &key, inode->i_ino);
-	err = ubifs_tnc_add(c, &key, lnum, offs + aligned_len1, len2);
+	err = ubifs_tnc_add(c, &key, lnum, offs + aligned_len1, len2, 0);
 	if (err)
 		goto out_ro;

diff --git a/fs/ubifs/replay.c b/fs/ubifs/replay.c
index b007637..f029b2d 100644
--- a/fs/ubifs/replay.c
+++ b/fs/ubifs/replay.c
@@ -252,7 +252,7 @@  static int apply_replay_entry(struct ubifs_info *c, struct replay_entry *r)
 			}
 		else
 			err = ubifs_tnc_add(c, &r->key, r->lnum, r->offs,
-					    r->len);
+					    r->len, 0);
 		if (err)
 			return err;

diff --git a/fs/ubifs/tnc.c b/fs/ubifs/tnc.c
index 16ad84d..b222a72 100644
--- a/fs/ubifs/tnc.c
+++ b/fs/ubifs/tnc.c
@@ -2158,13 +2158,14 @@  do_split:
  * @lnum: LEB number of node
  * @offs: node offset
  * @len: node length
+ * @crypto_lookup: the node's cryptographic key's position in the KSA
  *
  * This function adds a node with key @key to TNC. The node may be new or it may
  * obsolete some existing one. Returns %0 on success or negative error code on
  * failure.
  */
 int ubifs_tnc_add(struct ubifs_info *c, const union ubifs_key *key, int lnum,
-		  int offs, int len)
+		  int offs, int len, long long crypto_lookup)
 {
 	int found, n, err = 0;
 	struct ubifs_znode *znode;
@@ -2179,6 +2180,7 @@  int ubifs_tnc_add(struct ubifs_info *c, const union ubifs_key *key, int lnum,
 		zbr.lnum = lnum;
 		zbr.offs = offs;
 		zbr.len = len;
+		zbr.crypto_lookup = crypto_lookup;
 		key_copy(c, key, &zbr.key);
 		err = tnc_insert(c, znode, &zbr, n + 1);
 	} else if (found == 1) {
@@ -2189,6 +2191,7 @@  int ubifs_tnc_add(struct ubifs_info *c, const union ubifs_key *key, int lnum,
 		zbr->lnum = lnum;
 		zbr->offs = offs;
 		zbr->len = len;
+		zbr->crypto_lookup = crypto_lookup;
 	} else
 		err = found;
 	if (!err)
@@ -2207,13 +2210,15 @@  int ubifs_tnc_add(struct ubifs_info *c, const union ubifs_key *key, int lnum,
  * @lnum: LEB number of node
  * @offs: node offset
  * @len: node length
+ * @crypto_lookup: the node's updated cryptographic key's position in the KSA
  *
  * This function replaces a node with key @key in the TNC only if the old node
  * is found.  This function is called by garbage collection when node are moved.
  * Returns %0 on success or negative error code on failure.
  */
 int ubifs_tnc_replace(struct ubifs_info *c, const union ubifs_key *key,
-		      int old_lnum, int old_offs, int lnum, int offs, int len)
+		      int old_lnum, int old_offs, int lnum, int offs, int len,
+		      long long crypto_lookup)
 {
 	int found, n, err = 0;
 	struct ubifs_znode *znode;
@@ -2239,6 +2244,7 @@  int ubifs_tnc_replace(struct ubifs_info *c, const union ubifs_key *key,
 			zbr->lnum = lnum;
 			zbr->offs = offs;
 			zbr->len = len;
+			zbr->crypto_lookup = crypto_lookup;
 			found = 1;
 		} else if (is_hash_key(c, key)) {
 			found = resolve_collision_directly(c, key, &znode, &n,
@@ -2476,6 +2482,7 @@  static int tnc_delete(struct ubifs_info *c, struct ubifs_znode *znode, int n)
 			c->zroot.lnum = zbr->lnum;
 			c->zroot.offs = zbr->offs;
 			c->zroot.len = zbr->len;
+			c->zroot.crypto_lookup = zbr->crypto_lookup;
 			c->zroot.znode = znode;
 			ubifs_assert(!ubifs_zn_obsolete(zp));
 			ubifs_assert(ubifs_zn_dirty(zp));
diff --git a/fs/ubifs/tnc_misc.c b/fs/ubifs/tnc_misc.c
index dc28fe6..38fdfd0 100644
--- a/fs/ubifs/tnc_misc.c
+++ b/fs/ubifs/tnc_misc.c
@@ -309,6 +309,7 @@  static int read_znode(struct ubifs_info *c, int lnum, int offs, int len,
 		zbr->lnum = le32_to_cpu(br->lnum);
 		zbr->offs = le32_to_cpu(br->offs);
 		zbr->len  = le32_to_cpu(br->len);
+		zbr->crypto_lookup = 0;
 		zbr->znode = NULL;

 		/* Validate branch */
diff --git a/fs/ubifs/ubifs.h b/fs/ubifs/ubifs.h
index ce6d8c2..b777c0c 100644
--- a/fs/ubifs/ubifs.h
+++ b/fs/ubifs/ubifs.h
@@ -741,6 +741,7 @@  struct ubifs_jhead {
  * @lnum: LEB number of the target node (indexing node or data node)
  * @offs: target node offset within @lnum
  * @len: target node length
+ * @crypto_lookup: the node's cryptographic key's position in the KSA
  */
 struct ubifs_zbranch {
 	union ubifs_key key;
@@ -751,6 +752,7 @@  struct ubifs_zbranch {
 	int lnum;
 	int offs;
 	int len;
+	long long crypto_lookup;
 };

 /**
@@ -1580,9 +1582,10 @@  int ubifs_tnc_lookup_nm(struct ubifs_info *c, const union ubifs_key *key,
 int ubifs_tnc_locate(struct ubifs_info *c, const union ubifs_key *key,
 		     void *node, int *lnum, int *offs);
 int ubifs_tnc_add(struct ubifs_info *c, const union ubifs_key *key, int lnum,
-		  int offs, int len);
+		  int offs, int len, long long crypto_lookup);
 int ubifs_tnc_replace(struct ubifs_info *c, const union ubifs_key *key,
-		      int old_lnum, int old_offs, int lnum, int offs, int len);
+		      int old_lnum, int old_offs, int lnum, int offs, int len,
+		      long long crypto_lookup);
 int ubifs_tnc_add_nm(struct ubifs_info *c, const union ubifs_key *key,
 		     int lnum, int offs, int len, const struct qstr *nm);
 int ubifs_tnc_remove(struct ubifs_info *c, const union ubifs_key *key);