Kernel version: 2.6.17-mm1
When generating an encrypted file, the first page contains the header
information. ecryptfs allocates one page to be filled with the meta
information. ecryptfs_write_headers_virt() writes the header into the
page. The code in this function up to the call of
ecryptfs_generate_key_packet_set() already writes some bytes into the page
and moves the pointer forward accordingly.
This patch now tells ecryptfs_generate_key_packet_set() exactly how many
bytes it is allowed to write. Prior to that, the function would allow
PAGE_MAX_SIZE to be written which is longer than the allocated space
(remember, some bytes are already filled).
This problem does not really materialize in the current code as
ecryptfs_generate_key_packet_set() only writes a Tag 3 and Tag 11 with
less than 100 bytes. But this fix ensures that when development continues,
nobody stumbles over the problem without being warned.
Signed-off-by: Stephan Mueller <[email protected]>
---
fs/ecryptfs/crypto.c | 3 ++-
fs/ecryptfs/ecryptfs_kernel.h | 3 ++-
fs/ecryptfs/keystore.c | 15 +++++++++++----
3 files changed, 15 insertions(+), 6 deletions(-)
eb9ccb4c29456d611de189ae4ca95ad9111df751
diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
index 91b350e..02e4600 100644
--- a/fs/ecryptfs/crypto.c
+++ b/fs/ecryptfs/crypto.c
@@ -1224,7 +1224,8 @@ int ecryptfs_write_headers_virt(char *pa
write_header_metadata((page_virt + offset), crypt_stat, &written);
offset += written;
rc = ecryptfs_generate_key_packet_set((page_virt + offset), crypt_stat,
- ecryptfs_dentry, &written);
+ ecryptfs_dentry, &written,
+ PAGE_CACHE_SIZE - offset);
if (rc)
ecryptfs_printk(KERN_WARNING, "Error generating key packet "
"set; rc = [%d]\n", rc);
diff --git a/fs/ecryptfs/ecryptfs_kernel.h b/fs/ecryptfs/ecryptfs_kernel.h
index c37a452..4ce23f5 100644
--- a/fs/ecryptfs/ecryptfs_kernel.h
+++ b/fs/ecryptfs/ecryptfs_kernel.h
@@ -466,7 +466,8 @@ int ecryptfs_cipher_code_to_string(char
void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat);
int ecryptfs_generate_key_packet_set(char *dest_base,
struct ecryptfs_crypt_stat *crypt_stat,
- struct dentry *ecryptfs_dentry, int *len);
+ struct dentry *ecryptfs_dentry, int *len,
+ int max);
int process_request_key_err(long err_code);
int
ecryptfs_parse_packet_set(struct ecryptfs_crypt_stat *crypt_stat,
diff --git a/fs/ecryptfs/keystore.c b/fs/ecryptfs/keystore.c
index 4b9b742..a91b8b4 100644
--- a/fs/ecryptfs/keystore.c
+++ b/fs/ecryptfs/keystore.c
@@ -983,6 +983,7 @@ out:
* @ecryptfs_dentry: The dentry, used to retrieve the mount crypt stat
* for the global parameters
* @len: The amount written
+ * @max: The maximum amount of data allowed to be written
*
* Generates a key packet set and writes it to the virtual address
* passed in.
@@ -992,7 +993,8 @@ out:
int
ecryptfs_generate_key_packet_set(char *dest_base,
struct ecryptfs_crypt_stat *crypt_stat,
- struct dentry *ecryptfs_dentry, int *len)
+ struct dentry *ecryptfs_dentry, int *len,
+ int max)
{
int rc = 0;
struct ecryptfs_auth_tok *auth_tok;
@@ -1007,7 +1009,7 @@ ecryptfs_generate_key_packet_set(char *d
auth_tok = mount_crypt_stat->global_auth_tok;
if (ECRYPTFS_CHECK_FLAG(auth_tok->flags, ECRYPTFS_PASSWORD)) {
rc = write_tag_3_packet((dest_base + (*len)),
- PAGE_CACHE_SIZE, auth_tok,
+ max, auth_tok,
crypt_stat, &key_rec,
&written);
if (rc) {
@@ -1019,7 +1021,7 @@ ecryptfs_generate_key_packet_set(char *d
/* Write auth tok signature packet */
rc = write_tag_11_packet(
(dest_base + (*len)),
- (PAGE_CACHE_SIZE - (*len)),
+ (max - (*len)),
key_rec.sig, ECRYPTFS_SIG_SIZE, &written);
if (rc) {
ecryptfs_printk(KERN_ERR, "Error writing "
@@ -1043,7 +1045,12 @@ ecryptfs_generate_key_packet_set(char *d
}
} else
BUG();
- dest_base[(*len)] = 0x00;
+ if (likely((max - (*len)) > 0)) {
+ dest_base[(*len)] = 0x00;
+ } else {
+ ecryptfs_printk(KERN_ERR, "Error writing boundary byte\n");
+ rc = -EIO;
+ }
out:
if (rc)
(*len) = 0;
-
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