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-rw-r--r--fs/ecryptfs/miscdev.c56
1 files changed, 38 insertions, 18 deletions
diff --git a/fs/ecryptfs/miscdev.c b/fs/ecryptfs/miscdev.c
index 940a82e63dc3..0dc5a3d554a4 100644
--- a/fs/ecryptfs/miscdev.c
+++ b/fs/ecryptfs/miscdev.c
@@ -409,11 +409,47 @@ ecryptfs_miscdev_write(struct file *file, const char __user *buf,
ssize_t sz = 0;
char *data;
uid_t euid = current_euid();
+ unsigned char packet_size_peek[3];
int rc;
- if (count == 0)
+ if (count == 0) {
goto out;
+ } else if (count == (1 + 4)) {
+ /* 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)) {
+ 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);
+ return -EINVAL;
+ }
+
+ if (copy_from_user(packet_size_peek, (buf + 1 + 4),
+ 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 = [%d]\n", __func__, rc);
+ return rc;
+ }
+
+ if ((1 + 4 + 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",
@@ -435,23 +471,7 @@ ecryptfs_miscdev_write(struct file *file, const char __user *buf,
}
memcpy(&counter_nbo, &data[i], 4);
seq = be32_to_cpu(counter_nbo);
- i += 4;
- rc = ecryptfs_parse_packet_length(&data[i], &packet_size,
- &packet_size_length);
- 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;
- }
+ i += 4 + packet_size_length;
rc = ecryptfs_miscdev_response(&data[i], packet_size,
euid, current_user_ns(),
task_pid(current), seq);