Re: [PATCH] IMA: remove read permissions on the ima policy file

[Mimi Zohar]

On Tue, 2009-05-12 at 15:13 -0400, Eric Paris wrote:
> The IMA policy file does not implement read.  Trying to just open/read/close
> the file will load a blank policy and you cannot then change the policy
> without a reboot.  This removes the read permission from the file so one must
> at least be attempting to write...
> 
> Signed-off-by: Eric Paris <eparis@xxxxxxxxxx>

Acked-by: Mimi Zohar <zohar@xxxxxxxxxx>

> ---
> 
>  security/integrity/ima/ima_fs.c |    6 +++++-
>  1 files changed, 5 insertions(+), 1 deletions(-)
> 
> diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c
> index 510186f..2a829da 100644
> --- a/security/integrity/ima/ima_fs.c
> +++ b/security/integrity/ima/ima_fs.c
> @@ -15,6 +15,7 @@
>   *	implemenents security file system for reporting
>   *	current measurement list and IMA statistics
>   */
> +#include <linux/fcntl.h>
>  #include <linux/module.h>
>  #include <linux/seq_file.h>
>  #include <linux/rculist.h>
> @@ -283,6 +284,9 @@ static atomic_t policy_opencount = ATOMIC_INIT(1);
>   */
>  int ima_open_policy(struct inode * inode, struct file * filp)
>  {
> +	/* No point in being allowed to open it if you aren't going to write */
> +	if (!(filp->f_flags & O_WRONLY))
> +		return -EACCES;
>  	if (atomic_dec_and_test(&policy_opencount))
>  		return 0;
>  	return -EBUSY;
> @@ -349,7 +353,7 @@ int ima_fs_init(void)
>  		goto out;
> 
>  	ima_policy = securityfs_create_file("policy",
> -					    S_IRUSR | S_IRGRP | S_IWUSR,
> +					    S_IWUSR,
>  					    ima_dir, NULL,
>  					    &ima_measure_policy_ops);
>  	if (IS_ERR(ima_policy))
> 

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