1 files changed, 85 insertions, 55 deletions

diff --git a/fs/ecryptfs/miscdev.c b/fs/ecryptfs/miscdev.c
index 940a82e63dc3..349209dc6a91 100644
--- a/fs/ecryptfs/miscdev.c
+++ b/fs/ecryptfs/miscdev.c
@@ -218,6 +218,29 @@ out_unlock:
         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 @@ ecryptfs_miscdev_read(struct file *file, char __user *buf, size_t count,
         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 @@ check_list:
                 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 @@ check_list:
         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 @@ out:
  * @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
@@ -405,60 +416,78 @@ ecryptfs_miscdev_write(struct file *file, const char __user *buf,
 {
         __be32 counter_nbo;
         u32 seq;
-        size_t packet_size, packet_size_length, i;
-        ssize_t sz = 0;
+        size_t packet_size, packet_size_length;
         char *data;
         uid_t euid = current_euid();
-        int rc;
+        unsigned char packet_size_peek[ECRYPTFS_MAX_PKT_LEN_SIZE];
+        ssize_t rc;
 
-        if (count == 0)
-                goto out;
+        if (count == 0) {
+                return 0;
+        } else if (count == MIN_NON_MSG_PKT_SIZE) {
+                /* Likely a harmless MSG_HELO or MSG_QUIT - no packet length */
+                goto memdup;
+        } 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__, MIN_MSG_PKT_SIZE, MAX_MSG_PKT_SIZE, count);
+                return -EINVAL;
+        }
+
+        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__);
+                return -EFAULT;
+        }
 
+        rc = ecryptfs_parse_packet_length(packet_size_peek, &packet_size,
+                                          &packet_size_length);
+        if (rc) {
+                printk(KERN_WARNING "%s: Error parsing packet length; "
+                       "rc = [%zd]\n", __func__, rc);
+                return rc;
+        }
+
+        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;
+        }
+
+memdup:
         data = memdup_user(buf, count);
         if (IS_ERR(data)) {
                 printk(KERN_ERR "%s: memdup_user returned error [%ld]\n",
                        __func__, PTR_ERR(data));
-                goto out;
+                return PTR_ERR(data);
         }
-        sz = count;
-        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;
-                rc = ecryptfs_parse_packet_length(&data[i], &packet_size,
-                                                  &packet_size_length);
+                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: Error parsing packet length; "
-                               "rc = [%d]\n", __func__, rc);
-                        goto out_free;
-                }
-                i += packet_size_length;
-                if ((1 + 4 + packet_size_length + packet_size) != count) {
-                        printk(KERN_WARNING "%s: (1 + packet_size_length([%zd])"
-                               " + packet_size([%zd]))([%zd]) != "
-                               "count([%zd]). Invalid packet format.\n",
-                               __func__, packet_size_length, packet_size,
-                               (1 + packet_size_length + packet_size), count);
-                        goto out_free;
-                }
-                rc = ecryptfs_miscdev_response(&data[i], 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 = [%d]\n",
+                               "response to requesting operation; rc = [%zd]\n",
                                __func__, rc);
+                        goto out_free;
+                }
                 break;
         case ECRYPTFS_MSG_HELO:
         case ECRYPTFS_MSG_QUIT:
@@ -467,12 +496,13 @@ ecryptfs_miscdev_write(struct file *file, const char __user *buf,
                 ecryptfs_printk(KERN_WARNING, "Dropping miscdev "
                                 "message of unrecognized type [%d]\n",
                                 data[0]);
-                break;
+                rc = -EINVAL;
+                goto out_free;
         }
+        rc = count;
 out_free:
         kfree(data);
-out:
-        return sz;
+        return rc;
 }