IMA: maintain i_readcount in the VFS layer

ima_counts_get() updated the readcount and invalidated the PCR,
as necessary. Only update the i_readcount in the VFS layer.
Move the PCR invalidation checks to ima_file_check(), where it
belongs.

Maintaining the i_readcount in the VFS layer, will allow other
subsystems to use i_readcount.

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Acked-by: Eric Paris <eparis@redhat.com>

diff --git a/fs/file_table.c b/fs/file_table.c
index c3dee38..0c724de 100644 (file)
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -190,7 +190,8 @@ struct file *alloc_file(struct path *path, fmode_t mode,
                file_take_write(file);
                WARN_ON(mnt_clone_write(path->mnt));
        }
-       ima_counts_get(file);
+       if ((mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
+               i_readcount_inc(path->dentry->d_inode);
        return file;
 }
 EXPORT_SYMBOL(alloc_file);
@@ -251,6 +252,8 @@ static void __fput(struct file *file)
        fops_put(file->f_op);
        put_pid(file->f_owner.pid);
        file_sb_list_del(file);
+       if ((file->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
+               i_readcount_dec(inode);
        if (file->f_mode & FMODE_WRITE)
                drop_file_write_access(file);
        file->f_path.dentry = NULL;

diff --git a/fs/open.c b/fs/open.c
index 4197b9e..0d485c5 100644 (file)
--- a/fs/open.c
+++ b/fs/open.c
@@ -688,7 +688,8 @@ static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
                if (error)
                        goto cleanup_all;
        }
-       ima_counts_get(f);
+       if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
+               i_readcount_inc(inode);
 
        f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
 

diff --git a/include/linux/ima.h b/include/linux/ima.h
index 975837e..09e6e62 100644 (file)
--- a/include/linux/ima.h
+++ b/include/linux/ima.h
@@ -20,7 +20,6 @@ extern void ima_inode_free(struct inode *inode);
 extern int ima_file_check(struct file *file, int mask);
 extern void ima_file_free(struct file *file);
 extern int ima_file_mmap(struct file *file, unsigned long prot);
-extern void ima_counts_get(struct file *file);
 
 #else
 static inline int ima_bprm_check(struct linux_binprm *bprm)
@@ -53,10 +52,5 @@ static inline int ima_file_mmap(struct file *file, unsigned long prot)
        return 0;
 }
 
-static inline void ima_counts_get(struct file *file)
-{
-       return;
-}
-
 #endif /* CONFIG_IMA_H */
 #endif /* _LINUX_IMA_H */

diff --git a/security/integrity/ima/ima_iint.c b/security/integrity/ima/ima_iint.c
index f005355..68efe3b 100644 (file)
--- a/security/integrity/ima/ima_iint.c
+++ b/security/integrity/ima/ima_iint.c
@@ -141,8 +141,6 @@ void ima_inode_free(struct inode *inode)
                printk(KERN_INFO "%s: readcount: %u\n", __func__,
                       atomic_read(&inode->i_readcount));
 
-       atomic_set(&inode->i_readcount, 0);
-
        if (!IS_IMA(inode))
                return;
 

diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 6e8cb93..69b4856 100644 (file)
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -86,17 +86,16 @@ out:
 }
 
 /*
- * ima_counts_get - increment file counts
+ * ima_rdwr_violation_check
  *
- * Maintain read/write counters for all files, but only
- * invalidate the PCR for measured files:
+ * Only invalidate the PCR for measured files:
  *     - Opening a file for write when already open for read,
  *       results in a time of measure, time of use (ToMToU) error.
  *     - Opening a file for read when already open for write,
  *       could result in a file measurement error.
  *
  */
-void ima_counts_get(struct file *file)
+static void ima_rdwr_violation_check(struct file *file)
 {
        struct dentry *dentry = file->f_path.dentry;
        struct inode *inode = dentry->d_inode;
@@ -104,13 +103,10 @@ void ima_counts_get(struct file *file)
        int rc;
        bool send_tomtou = false, send_writers = false;
 
-       if (!S_ISREG(inode->i_mode))
+       if (!S_ISREG(inode->i_mode) || !ima_initialized)
                return;
 
-       spin_lock(&inode->i_lock);
-
-       if (!ima_initialized)
-               goto out;
+       mutex_lock(&inode->i_mutex);    /* file metadata: permissions, xattr */
 
        if (mode & FMODE_WRITE) {
                if (atomic_read(&inode->i_readcount) && IS_IMA(inode))
@@ -125,11 +121,7 @@ void ima_counts_get(struct file *file)
        if (atomic_read(&inode->i_writecount) > 0)
                send_writers = true;
 out:
-       /* remember the vfs deals with i_writecount */
-       if ((mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
-               atomic_inc(&inode->i_readcount);
-
-       spin_unlock(&inode->i_lock);
+       mutex_unlock(&inode->i_mutex);
 
        if (send_tomtou)
                ima_add_violation(inode, dentry->d_name.name, "invalid_pcr",
@@ -158,7 +150,6 @@ static void ima_dec_counts(struct inode *inode, struct file *file)
                        }
                        return;
                }
-               atomic_dec(&inode->i_readcount);
        }
 }
 
@@ -203,8 +194,7 @@ static void ima_file_free_noiint(struct inode *inode, struct file *file)
  * ima_file_free - called on __fput()
  * @file: pointer to file structure being freed
  *
- * Flag files that changed, based on i_version;
- * and decrement the i_readcount.
+ * Flag files that changed, based on i_version
  */
 void ima_file_free(struct file *file)
 {
@@ -318,6 +308,7 @@ int ima_file_check(struct file *file, int mask)
 {
        int rc;
 
+       ima_rdwr_violation_check(file);
        rc = process_measurement(file, file->f_dentry->d_name.name,
                                 mask & (MAY_READ | MAY_WRITE | MAY_EXEC),
                                 FILE_CHECK);