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>
This commit is contained in:
Родитель
7f13350424
Коммит
48399c0b0e
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@ -151,6 +151,11 @@ ecryptfs_get_key_payload_data(struct key *key)
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* dentry name */
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#define ECRYPTFS_TAG_73_PACKET_TYPE 0x49 /* FEK-encrypted filename as
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* metadata */
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#define ECRYPTFS_MIN_PKT_LEN_SIZE 1 /* Min size to specify packet length */
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#define ECRYPTFS_MAX_PKT_LEN_SIZE 2 /* Pass at least this many bytes to
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* ecryptfs_parse_packet_length() and
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* ecryptfs_write_packet_length()
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*/
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/* Constraint: ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES >=
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* ECRYPTFS_MAX_IV_BYTES */
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#define ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES 16
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@ -109,7 +109,7 @@ int ecryptfs_parse_packet_length(unsigned char *data, size_t *size,
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(*size) += ((unsigned char)(data[1]) + 192);
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(*length_size) = 2;
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} else if (data[0] == 255) {
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/* Five-byte length; we're not supposed to see this */
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/* If support is added, adjust ECRYPTFS_MAX_PKT_LEN_SIZE */
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ecryptfs_printk(KERN_ERR, "Five-byte packet length not "
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"supported\n");
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rc = -EINVAL;
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@ -126,7 +126,7 @@ out:
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/**
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* ecryptfs_write_packet_length
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* @dest: The byte array target into which to write the length. Must
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* have at least 5 bytes allocated.
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* have at least ECRYPTFS_MAX_PKT_LEN_SIZE bytes allocated.
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* @size: The length to write.
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* @packet_size_length: The number of bytes used to encode the packet
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* length is written to this address.
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@ -146,6 +146,7 @@ int ecryptfs_write_packet_length(char *dest, size_t size,
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dest[1] = ((size - 192) % 256);
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(*packet_size_length) = 2;
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} else {
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/* If support is added, adjust ECRYPTFS_MAX_PKT_LEN_SIZE */
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rc = -EINVAL;
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ecryptfs_printk(KERN_WARNING,
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"Unsupported packet size: [%zd]\n", size);
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@ -218,6 +218,29 @@ out_unlock:
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return rc;
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}
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/*
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* miscdevfs packet format:
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* Octet 0: Type
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* Octets 1-4: network byte order msg_ctx->counter
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* Octets 5-N0: Size of struct ecryptfs_message to follow
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* Octets N0-N1: struct ecryptfs_message (including data)
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*
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* Octets 5-N1 not written if the packet type does not include a message
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*/
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#define PKT_TYPE_SIZE 1
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#define PKT_CTR_SIZE 4
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#define MIN_NON_MSG_PKT_SIZE (PKT_TYPE_SIZE + PKT_CTR_SIZE)
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#define MIN_MSG_PKT_SIZE (PKT_TYPE_SIZE + PKT_CTR_SIZE \
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+ ECRYPTFS_MIN_PKT_LEN_SIZE)
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/* 4 + ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES comes from tag 65 packet format */
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#define MAX_MSG_PKT_SIZE (PKT_TYPE_SIZE + PKT_CTR_SIZE \
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+ ECRYPTFS_MAX_PKT_LEN_SIZE \
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+ sizeof(struct ecryptfs_message) \
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+ 4 + ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES)
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#define PKT_TYPE_OFFSET 0
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#define PKT_CTR_OFFSET PKT_TYPE_SIZE
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#define PKT_LEN_OFFSET (PKT_TYPE_SIZE + PKT_CTR_SIZE)
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/**
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* ecryptfs_miscdev_read - format and send message from queue
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* @file: fs/ecryptfs/euid miscdevfs handle (ignored)
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@ -237,7 +260,7 @@ ecryptfs_miscdev_read(struct file *file, char __user *buf, size_t count,
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struct ecryptfs_daemon *daemon;
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struct ecryptfs_msg_ctx *msg_ctx;
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size_t packet_length_size;
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char packet_length[3];
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char packet_length[ECRYPTFS_MAX_PKT_LEN_SIZE];
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size_t i;
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size_t total_length;
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uid_t euid = current_euid();
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@ -305,15 +328,8 @@ check_list:
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packet_length_size = 0;
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msg_ctx->msg_size = 0;
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}
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/* miscdevfs packet format:
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* Octet 0: Type
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* Octets 1-4: network byte order msg_ctx->counter
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* Octets 5-N0: Size of struct ecryptfs_message to follow
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* Octets N0-N1: struct ecryptfs_message (including data)
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*
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* Octets 5-N1 not written if the packet type does not
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* include a message */
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total_length = (1 + 4 + packet_length_size + msg_ctx->msg_size);
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total_length = (PKT_TYPE_SIZE + PKT_CTR_SIZE + packet_length_size
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+ msg_ctx->msg_size);
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if (count < total_length) {
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rc = 0;
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printk(KERN_WARNING "%s: Only given user buffer of "
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@ -324,9 +340,10 @@ check_list:
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rc = -EFAULT;
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if (put_user(msg_ctx->type, buf))
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goto out_unlock_msg_ctx;
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if (put_user(cpu_to_be32(msg_ctx->counter), (__be32 __user *)(buf + 1)))
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if (put_user(cpu_to_be32(msg_ctx->counter),
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(__be32 __user *)(&buf[PKT_CTR_OFFSET])))
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goto out_unlock_msg_ctx;
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i = 5;
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i = PKT_TYPE_SIZE + PKT_CTR_SIZE;
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if (msg_ctx->msg) {
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if (copy_to_user(&buf[i], packet_length, packet_length_size))
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goto out_unlock_msg_ctx;
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@ -391,12 +408,6 @@ out:
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* @count: Amount of data in @buf
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* @ppos: Pointer to offset in file (ignored)
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*
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* miscdevfs packet format:
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* Octet 0: Type
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* Octets 1-4: network byte order msg_ctx->counter (0's for non-response)
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* Octets 5-N0: Size of struct ecryptfs_message to follow
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* Octets N0-N1: struct ecryptfs_message (including data)
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*
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* Returns the number of bytes read from @buf
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*/
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static ssize_t
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@ -405,29 +416,25 @@ ecryptfs_miscdev_write(struct file *file, const char __user *buf,
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{
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__be32 counter_nbo;
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u32 seq;
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size_t packet_size, packet_size_length, i;
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size_t packet_size, packet_size_length;
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char *data;
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uid_t euid = current_euid();
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unsigned char packet_size_peek[3];
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unsigned char packet_size_peek[ECRYPTFS_MAX_PKT_LEN_SIZE];
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ssize_t rc;
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if (count == 0) {
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return 0;
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} else if (count == (1 + 4)) {
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} else if (count == MIN_NON_MSG_PKT_SIZE) {
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/* Likely a harmless MSG_HELO or MSG_QUIT - no packet length */
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goto memdup;
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} else if (count < (1 + 4 + 1)
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|| count > (1 + 4 + 2 + sizeof(struct ecryptfs_message) + 4
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+ ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES)) {
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} else if (count < MIN_MSG_PKT_SIZE || count > MAX_MSG_PKT_SIZE) {
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printk(KERN_WARNING "%s: Acceptable packet size range is "
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"[%d-%lu], but amount of data written is [%zu].",
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__func__, (1 + 4 + 1),
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(1 + 4 + 2 + sizeof(struct ecryptfs_message) + 4
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+ ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES), count);
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__func__, MIN_MSG_PKT_SIZE, MAX_MSG_PKT_SIZE, count);
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return -EINVAL;
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}
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if (copy_from_user(packet_size_peek, (buf + 1 + 4),
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if (copy_from_user(packet_size_peek, &buf[PKT_LEN_OFFSET],
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sizeof(packet_size_peek))) {
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printk(KERN_WARNING "%s: Error while inspecting packet size\n",
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__func__);
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@ -442,7 +449,8 @@ ecryptfs_miscdev_write(struct file *file, const char __user *buf,
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return rc;
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}
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if ((1 + 4 + packet_size_length + packet_size) != count) {
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if ((PKT_TYPE_SIZE + PKT_CTR_SIZE + packet_size_length + packet_size)
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!= count) {
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printk(KERN_WARNING "%s: Invalid packet size [%zu]\n", __func__,
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packet_size);
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return -EINVAL;
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@ -455,25 +463,25 @@ memdup:
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__func__, PTR_ERR(data));
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return PTR_ERR(data);
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}
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i = 0;
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switch (data[i++]) {
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switch (data[PKT_TYPE_OFFSET]) {
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case ECRYPTFS_MSG_RESPONSE:
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if (count < (1 + 4 + 1 + sizeof(struct ecryptfs_message))) {
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if (count < (MIN_MSG_PKT_SIZE
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+ sizeof(struct ecryptfs_message))) {
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printk(KERN_WARNING "%s: Minimum acceptable packet "
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"size is [%zd], but amount of data written is "
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"only [%zd]. Discarding response packet.\n",
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__func__,
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(1 + 4 + 1 + sizeof(struct ecryptfs_message)),
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count);
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(MIN_MSG_PKT_SIZE
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+ sizeof(struct ecryptfs_message)), count);
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rc = -EINVAL;
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goto out_free;
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}
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memcpy(&counter_nbo, &data[i], 4);
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memcpy(&counter_nbo, &data[PKT_CTR_OFFSET], PKT_CTR_SIZE);
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seq = be32_to_cpu(counter_nbo);
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i += 4 + packet_size_length;
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rc = ecryptfs_miscdev_response(&data[i], packet_size,
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euid, current_user_ns(),
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task_pid(current), seq);
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rc = ecryptfs_miscdev_response(
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&data[PKT_LEN_OFFSET + packet_size_length],
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packet_size, euid, current_user_ns(),
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task_pid(current), seq);
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if (rc) {
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printk(KERN_WARNING "%s: Failed to deliver miscdev "
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"response to requesting operation; rc = [%zd]\n",
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