eCryptfs: Replace miscdev read/write magic numbers
ecryptfs_miscdev_read() and ecryptfs_miscdev_write() contained many
magic numbers for specifying packet header field sizes and offsets. This
patch defines those values and replaces the magic values.
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
diff --git a/fs/ecryptfs/miscdev.c b/fs/ecryptfs/miscdev.c
index 1145c58..349209d 100644
--- a/fs/ecryptfs/miscdev.c
+++ b/fs/ecryptfs/miscdev.c
@@ -218,6 +218,29 @@
return rc;
}
+/*
+ * miscdevfs packet format:
+ * Octet 0: Type
+ * Octets 1-4: network byte order msg_ctx->counter
+ * Octets 5-N0: Size of struct ecryptfs_message to follow
+ * Octets N0-N1: struct ecryptfs_message (including data)
+ *
+ * Octets 5-N1 not written if the packet type does not include a message
+ */
+#define PKT_TYPE_SIZE 1
+#define PKT_CTR_SIZE 4
+#define MIN_NON_MSG_PKT_SIZE (PKT_TYPE_SIZE + PKT_CTR_SIZE)
+#define MIN_MSG_PKT_SIZE (PKT_TYPE_SIZE + PKT_CTR_SIZE \
+ + ECRYPTFS_MIN_PKT_LEN_SIZE)
+/* 4 + ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES comes from tag 65 packet format */
+#define MAX_MSG_PKT_SIZE (PKT_TYPE_SIZE + PKT_CTR_SIZE \
+ + ECRYPTFS_MAX_PKT_LEN_SIZE \
+ + sizeof(struct ecryptfs_message) \
+ + 4 + ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES)
+#define PKT_TYPE_OFFSET 0
+#define PKT_CTR_OFFSET PKT_TYPE_SIZE
+#define PKT_LEN_OFFSET (PKT_TYPE_SIZE + PKT_CTR_SIZE)
+
/**
* ecryptfs_miscdev_read - format and send message from queue
* @file: fs/ecryptfs/euid miscdevfs handle (ignored)
@@ -237,7 +260,7 @@
struct ecryptfs_daemon *daemon;
struct ecryptfs_msg_ctx *msg_ctx;
size_t packet_length_size;
- char packet_length[3];
+ char packet_length[ECRYPTFS_MAX_PKT_LEN_SIZE];
size_t i;
size_t total_length;
uid_t euid = current_euid();
@@ -305,15 +328,8 @@
packet_length_size = 0;
msg_ctx->msg_size = 0;
}
- /* miscdevfs packet format:
- * Octet 0: Type
- * Octets 1-4: network byte order msg_ctx->counter
- * Octets 5-N0: Size of struct ecryptfs_message to follow
- * Octets N0-N1: struct ecryptfs_message (including data)
- *
- * Octets 5-N1 not written if the packet type does not
- * include a message */
- total_length = (1 + 4 + packet_length_size + msg_ctx->msg_size);
+ total_length = (PKT_TYPE_SIZE + PKT_CTR_SIZE + packet_length_size
+ + msg_ctx->msg_size);
if (count < total_length) {
rc = 0;
printk(KERN_WARNING "%s: Only given user buffer of "
@@ -324,9 +340,10 @@
rc = -EFAULT;
if (put_user(msg_ctx->type, buf))
goto out_unlock_msg_ctx;
- if (put_user(cpu_to_be32(msg_ctx->counter), (__be32 __user *)(buf + 1)))
+ if (put_user(cpu_to_be32(msg_ctx->counter),
+ (__be32 __user *)(&buf[PKT_CTR_OFFSET])))
goto out_unlock_msg_ctx;
- i = 5;
+ i = PKT_TYPE_SIZE + PKT_CTR_SIZE;
if (msg_ctx->msg) {
if (copy_to_user(&buf[i], packet_length, packet_length_size))
goto out_unlock_msg_ctx;
@@ -391,12 +408,6 @@
* @count: Amount of data in @buf
* @ppos: Pointer to offset in file (ignored)
*
- * miscdevfs packet format:
- * Octet 0: Type
- * Octets 1-4: network byte order msg_ctx->counter (0's for non-response)
- * Octets 5-N0: Size of struct ecryptfs_message to follow
- * Octets N0-N1: struct ecryptfs_message (including data)
- *
* Returns the number of bytes read from @buf
*/
static ssize_t
@@ -405,29 +416,25 @@
{
__be32 counter_nbo;
u32 seq;
- size_t packet_size, packet_size_length, i;
+ size_t packet_size, packet_size_length;
char *data;
uid_t euid = current_euid();
- unsigned char packet_size_peek[3];
+ unsigned char packet_size_peek[ECRYPTFS_MAX_PKT_LEN_SIZE];
ssize_t rc;
if (count == 0) {
return 0;
- } else if (count == (1 + 4)) {
+ } else if (count == MIN_NON_MSG_PKT_SIZE) {
/* Likely a harmless MSG_HELO or MSG_QUIT - no packet length */
goto memdup;
- } else if (count < (1 + 4 + 1)
- || count > (1 + 4 + 2 + sizeof(struct ecryptfs_message) + 4
- + ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES)) {
+ } else if (count < MIN_MSG_PKT_SIZE || count > MAX_MSG_PKT_SIZE) {
printk(KERN_WARNING "%s: Acceptable packet size range is "
"[%d-%lu], but amount of data written is [%zu].",
- __func__, (1 + 4 + 1),
- (1 + 4 + 2 + sizeof(struct ecryptfs_message) + 4
- + ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES), count);
+ __func__, MIN_MSG_PKT_SIZE, MAX_MSG_PKT_SIZE, count);
return -EINVAL;
}
- if (copy_from_user(packet_size_peek, (buf + 1 + 4),
+ if (copy_from_user(packet_size_peek, &buf[PKT_LEN_OFFSET],
sizeof(packet_size_peek))) {
printk(KERN_WARNING "%s: Error while inspecting packet size\n",
__func__);
@@ -442,7 +449,8 @@
return rc;
}
- if ((1 + 4 + packet_size_length + packet_size) != count) {
+ if ((PKT_TYPE_SIZE + PKT_CTR_SIZE + packet_size_length + packet_size)
+ != count) {
printk(KERN_WARNING "%s: Invalid packet size [%zu]\n", __func__,
packet_size);
return -EINVAL;
@@ -455,25 +463,25 @@
__func__, PTR_ERR(data));
return PTR_ERR(data);
}
- i = 0;
- switch (data[i++]) {
+ switch (data[PKT_TYPE_OFFSET]) {
case ECRYPTFS_MSG_RESPONSE:
- if (count < (1 + 4 + 1 + sizeof(struct ecryptfs_message))) {
+ if (count < (MIN_MSG_PKT_SIZE
+ + sizeof(struct ecryptfs_message))) {
printk(KERN_WARNING "%s: Minimum acceptable packet "
"size is [%zd], but amount of data written is "
"only [%zd]. Discarding response packet.\n",
__func__,
- (1 + 4 + 1 + sizeof(struct ecryptfs_message)),
- count);
+ (MIN_MSG_PKT_SIZE
+ + sizeof(struct ecryptfs_message)), count);
rc = -EINVAL;
goto out_free;
}
- memcpy(&counter_nbo, &data[i], 4);
+ memcpy(&counter_nbo, &data[PKT_CTR_OFFSET], PKT_CTR_SIZE);
seq = be32_to_cpu(counter_nbo);
- i += 4 + packet_size_length;
- rc = ecryptfs_miscdev_response(&data[i], packet_size,
- euid, current_user_ns(),
- task_pid(current), seq);
+ rc = ecryptfs_miscdev_response(
+ &data[PKT_LEN_OFFSET + packet_size_length],
+ packet_size, euid, current_user_ns(),
+ task_pid(current), seq);
if (rc) {
printk(KERN_WARNING "%s: Failed to deliver miscdev "
"response to requesting operation; rc = [%zd]\n",