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IMA: remove read permissions on the ima policy file 

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@redhat.com>
Acked-by: Mimi Zohar <zohar@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
This commit is contained in:
Eric Paris 2009-05-12 15:13:55 -04:00 committed by James Morris
parent b103387037
commit f850a7c040
1 changed files with 5 additions and 1 deletions
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6
security/integrity/ima/ima_fs.c
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@ -15,6 +15,7 @@
* implemenents security file system for reporting * implemenents security file system for reporting
* current measurement list and IMA statistics * current measurement list and IMA statistics
*/ */
#include <linux/fcntl.h>
#include <linux/module.h> #include <linux/module.h>
#include <linux/seq_file.h> #include <linux/seq_file.h>
#include <linux/rculist.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) 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)) if (atomic_dec_and_test(&policy_opencount))
return 0; return 0;
return -EBUSY; return -EBUSY;
@ -349,7 +353,7 @@ int ima_fs_init(void)
goto out; goto out;
ima_policy = securityfs_create_file("policy", ima_policy = securityfs_create_file("policy",
S_IRUSR | S_IRGRP | S_IWUSR, S_IWUSR,
ima_dir, NULL, ima_dir, NULL,
&ima_measure_policy_ops); &ima_measure_policy_ops);
if (IS_ERR(ima_policy)) if (IS_ERR(ima_policy))