NOTE: this is actually test code, that will change before final
submission, ensuring the new checksum format works. whole-object GET
can be verified by client via stored whole-object checksum, which is
passed in GET's struct chunksrv_resp.
Partial-GET (ranged GET) will employ a similar code path, and will use a
modified version of the checking found below.
chunkd/be-fs.c | 51 ++++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 50 insertions(+), 1 deletion(-)
commit 825525f85655204fffefddcb95dfa9c2c7572b80
Author: Jeff Garzik <jeff@xxxxxxxxxx>
Date: Mon Jul 19 19:48:47 2010 -0400
[chunkd] checksum data prior to returning via GET
When reading a file off disk, checksum the data after reading from
disk, prior to sending across network to client. Fail read, if
checksum fails.
This guarantees we will never send corrupted data to a client.
Signed-off-by: Jeff Garzik <jgarzik@xxxxxxxxxx>
diff --git a/chunkd/be-fs.c b/chunkd/be-fs.c
index d714e7c..24baad7 100644
--- a/chunkd/be-fs.c
+++ b/chunkd/be-fs.c
@@ -52,8 +52,12 @@ struct fs_obj {
int in_fd;
char *in_fn;
+ off_t in_pos;
off_t sendfile_ofs;
+ off_t tail_pos;
+ size_t tail_len;
+
size_t checked_bytes;
SHA_CTX checksum;
unsigned int csum_idx;
@@ -368,6 +372,8 @@ struct backend_obj *fs_obj_new(uint32_t table_id,
if (!obj->csum_tbl)
goto err_out;
obj->csum_tbl_sz = csum_bytes;
+ obj->tail_pos = data_len & ~(CHUNK_BLK_SZ - 1);
+ obj->tail_len = data_len & (CHUNK_BLK_SZ - 1);
/* build local fs pathname */
fn = fs_obj_pathname(table_id, key, key_len);
@@ -492,6 +498,8 @@ struct backend_obj *fs_obj_open(uint32_t table_id, const char *user,
value_len = GUINT64_FROM_LE(hdr.value_len);
obj->n_blk = GUINT32_FROM_LE(hdr.n_blk);
csum_bytes = obj->n_blk * CHD_CSUM_SZ;
+ obj->tail_pos = value_len & ~(CHUNK_BLK_SZ - 1);
+ obj->tail_len = value_len & (CHUNK_BLK_SZ - 1);
/* verify file size large enough to contain value */
tmp64 = value_len + sizeof(hdr) + key_len + csum_bytes;
@@ -575,15 +583,56 @@ void fs_obj_free(struct backend_obj *bo)
free(obj);
}
+static bool can_csum_blk(struct fs_obj *obj, size_t len)
+{
+ if (obj->in_pos & (CHUNK_BLK_SZ - 1))
+ return false;
+
+ if (obj->in_pos == obj->tail_pos && len == obj->tail_len)
+ return true;
+ if (len == CHUNK_BLK_SZ)
+ return true;
+
+ return false;
+}
+
ssize_t fs_obj_read(struct backend_obj *bo, void *ptr, size_t len)
{
struct fs_obj *obj = bo->private;
ssize_t rc;
rc = read(obj->in_fd, ptr, len);
- if (rc < 0)
+ if (rc < 0) {
applog(LOG_ERR, "obj read(%s) failed: %s",
obj->in_fn, strerror(errno));
+ return -errno;
+ }
+
+ if (can_csum_blk(obj, rc)) {
+ unsigned char md[CHD_CSUM_SZ];
+ unsigned int blk_pos;
+ int cmprc;
+
+ SHA1(ptr, rc, md);
+
+ blk_pos = (unsigned int) (obj->in_pos >> CHUNK_BLK_ORDER);
+ cmprc = memcmp(md, obj->csum_tbl + (blk_pos * CHD_CSUM_SZ),
+ CHD_CSUM_SZ);
+
+ if (cmprc) {
+ applog(LOG_WARNING, "obj(%s) csum failed @ 0x%llx",
+ obj->in_fn,
+ (unsigned long long) obj->in_pos);
+ return -EIO;
+ }
+ } else {
+ applog(LOG_INFO, "obj(%s) unaligned read, 0x%x @ 0x%llx",
+ obj->in_fn, len,
+ (unsigned long long) obj->in_pos);
+
+ }
+
+ obj->in_pos += rc;
return rc;
}
--
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