Hi all!
I have some trouble reading a 2346 byte /proc entry from our Umbrella kernel
module.
Proc file is created write-only and I am able to write text to the file, and
read it from kernel space. The function reading the entry is in short this:
static int umb_proc_write(struct file *file, const char *buffer,
unsigned long count, void *data) {
char *policy;
int *lbuf;
int i;
if (count != UMB_POLICY_SIZE) {
printk("Umbrella: Error - /proc/umbrella is of invalid size\n");
return -EFAULT;
}
/* Initialization of lbuf */
policy = kmalloc(sizeof(char)*UMB_POLICY_SIZE, GFP_ATOMIC);
lbuf = kmalloc(count, GFP_KERNEL);
if (!lbuf || !policy) {
kfree(lbuf);
kfree(policy);
return -EFAULT;
}
if (copy_from_user(lbuf, buffer, count)) {
kfree(lbuf);
kfree(policy);
return -EFAULT;
}
strcpy(policy, lbuf);
umb_parse_proc(policy);
}
If I read byte by byte will only give the characters on every fourth index.
E.g. reading lbuf with the string "abcd", then lbuf[0]==a and lbuf[1]==d ...
- Do anyone have an explanation for this behaviour? Making the strcpy does fix
the problem - and the complete string is available! :-/ ...
Now that everything works, I want to write a string of excactly 2346
characters to the /proc/umbrella file. However when I make the
copy_from_user, I only get the first 1003 characters :-((
- Do you have a pointer to where I do this thing wrong?
What is the limit regarding the size of writing a /proc entry? (we consider
importing binary public keys to the kernel this way in the future).
Best regards,
Kristian.
--
Kristian Sørensen
- The Umbrella Project -- Security for Consumer Electronics
http://umbrella.sourceforge.net
E-mail: [EMAIL PROTECTED], Phone: +45 29723816
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
