fix ima breakage

The "Untangling ima mess, part 2 with counters" patch messed
up the counters.  Based on conversations with Al Viro, this patch
streamlines ima_path_check() by removing the counter maintaince.
The counters are now updated independently, from measuring the file,
in __dentry_open() and alloc_file() by calling ima_counts_get().
ima_path_check() is called from nfsd and do_filp_open().
It also did not measure all files that should have been measured.
Reason: ima_path_check() got bogus value passed as mask.
[AV: mea culpa]
[AV: add missing nfsd bits]

Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 92 insertions, 144 deletions

diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index a89f44d5e03..75aee18f616 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -84,6 +84,36 @@ out:
         return found;
 }
 
+/* ima_read_write_check - reflect possible reading/writing errors in the PCR.
+ *
+ * When opening a file for read, if the file is already open for write,
+ * the file could change, resulting in a file measurement error.
+ *
+ * Opening a file for write, if the file is already open for read, results
+ * in a time of measure, time of use (ToMToU) error.
+ *
+ * In either case invalidate the PCR.
+ */
+enum iint_pcr_error { TOMTOU, OPEN_WRITERS };
+static void ima_read_write_check(enum iint_pcr_error error,
+                                 struct ima_iint_cache *iint,
+                                 struct inode *inode,
+                                 const unsigned char *filename)
+{
+        switch (error) {
+        case TOMTOU:
+                if (iint->readcount > 0)
+                        ima_add_violation(inode, filename, "invalid_pcr",
+                                          "ToMToU");
+                break;
+        case OPEN_WRITERS:
+                if (iint->writecount > 0)
+                        ima_add_violation(inode, filename, "invalid_pcr",
+                                          "open_writers");
+                break;
+        }
+}
+
 /*
  * Update the counts given an fmode_t
  */
@@ -99,6 +129,47 @@ static void ima_inc_counts(struct ima_iint_cache *iint, fmode_t mode)
 }
 
 /*
+ * ima_counts_get - increment file counts
+ *
+ * Maintain read/write counters for all files, but 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)
+{
+        struct dentry *dentry = file->f_path.dentry;
+        struct inode *inode = dentry->d_inode;
+        fmode_t mode = file->f_mode;
+        struct ima_iint_cache *iint;
+        int rc;
+
+        if (!ima_initialized || !S_ISREG(inode->i_mode))
+                return;
+        iint = ima_iint_find_get(inode);
+        if (!iint)
+                return;
+        mutex_lock(&iint->mutex);
+        rc = ima_must_measure(iint, inode, MAY_READ, PATH_CHECK);
+        if (rc < 0)
+                goto out;
+
+        if (mode & FMODE_WRITE) {
+                ima_read_write_check(TOMTOU, iint, inode, dentry->d_name.name);
+                goto out;
+        }
+        ima_read_write_check(OPEN_WRITERS, iint, inode, dentry->d_name.name);
+out:
+        ima_inc_counts(iint, file->f_mode);
+        mutex_unlock(&iint->mutex);
+
+        kref_put(&iint->refcount, iint_free);
+}
+
+/*
  * Decrement ima counts
  */
 static void ima_dec_counts(struct ima_iint_cache *iint, struct inode *inode,
@@ -153,123 +224,6 @@ void ima_file_free(struct file *file)
         kref_put(&iint->refcount, iint_free);
 }
 
-/* ima_read_write_check - reflect possible reading/writing errors in the PCR.
- *
- * When opening a file for read, if the file is already open for write,
- * the file could change, resulting in a file measurement error.
- *
- * Opening a file for write, if the file is already open for read, results
- * in a time of measure, time of use (ToMToU) error.
- *
- * In either case invalidate the PCR.
- */
-enum iint_pcr_error { TOMTOU, OPEN_WRITERS };
-static void ima_read_write_check(enum iint_pcr_error error,
-                                 struct ima_iint_cache *iint,
-                                 struct inode *inode,
-                                 const unsigned char *filename)
-{
-        switch (error) {
-        case TOMTOU:
-                if (iint->readcount > 0)
-                        ima_add_violation(inode, filename, "invalid_pcr",
-                                          "ToMToU");
-                break;
-        case OPEN_WRITERS:
-                if (iint->writecount > 0)
-                        ima_add_violation(inode, filename, "invalid_pcr",
-                                          "open_writers");
-                break;
-        }
-}
-
-static int get_path_measurement(struct ima_iint_cache *iint, struct file *file,
-                                const unsigned char *filename)
-{
-        int rc = 0;
-
-        ima_inc_counts(iint, file->f_mode);
-
-        rc = ima_collect_measurement(iint, file);
-        if (!rc)
-                ima_store_measurement(iint, file, filename);
-        return rc;
-}
-
-/**
- * ima_path_check - based on policy, collect/store measurement.
- * @path: contains a pointer to the path to be measured
- * @mask: contains MAY_READ, MAY_WRITE or MAY_EXECUTE
- *
- * Measure the file being open for readonly, based on the
- * ima_must_measure() policy decision.
- *
- * Keep read/write counters for all files, but 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.
- *
- * Always return 0 and audit dentry_open failures.
- * (Return code will be based upon measurement appraisal.)
- */
-int ima_path_check(struct path *path, int mask)
-{
-        struct inode *inode = path->dentry->d_inode;
-        struct ima_iint_cache *iint;
-        struct file *file = NULL;
-        int rc;
-
-        if (!ima_initialized || !S_ISREG(inode->i_mode))
-                return 0;
-        iint = ima_iint_find_get(inode);
-        if (!iint)
-                return 0;
-
-        mutex_lock(&iint->mutex);
-
-        rc = ima_must_measure(iint, inode, MAY_READ, PATH_CHECK);
-        if (rc < 0)
-                goto out;
-
-        if ((mask & MAY_WRITE) || (mask == 0))
-                ima_read_write_check(TOMTOU, iint, inode,
-                                     path->dentry->d_name.name);
-
-        if ((mask & (MAY_WRITE | MAY_READ | MAY_EXEC)) != MAY_READ)
-                goto out;
-
-        ima_read_write_check(OPEN_WRITERS, iint, inode,
-                             path->dentry->d_name.name);
-        if (!(iint->flags & IMA_MEASURED)) {
-                struct dentry *dentry = dget(path->dentry);
-                struct vfsmount *mnt = mntget(path->mnt);
-
-                file = dentry_open(dentry, mnt, O_RDONLY | O_LARGEFILE,
-                                   current_cred());
-                if (IS_ERR(file)) {
-                        int audit_info = 0;
-
-                        integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode,
-                                            dentry->d_name.name,
-                                            "add_measurement",
-                                            "dentry_open failed",
-                                            1, audit_info);
-                        file = NULL;
-                        goto out;
-                }
-                rc = get_path_measurement(iint, file, dentry->d_name.name);
-        }
-out:
-        mutex_unlock(&iint->mutex);
-        if (file)
-                fput(file);
-        kref_put(&iint->refcount, iint_free);
-        return 0;
-}
-EXPORT_SYMBOL_GPL(ima_path_check);
-
 static int process_measurement(struct file *file, const unsigned char *filename,
                                int mask, int function)
 {
@@ -297,33 +251,6 @@ out:
         return rc;
 }
 
-/*
- * ima_counts_get - increment file counts
- *
- * - for IPC shm and shmat file.
- * - for nfsd exported files.
- *
- * Increment the counts for these files to prevent unnecessary
- * imbalance messages.
- */
-void ima_counts_get(struct file *file)
-{
-        struct inode *inode = file->f_dentry->d_inode;
-        struct ima_iint_cache *iint;
-
-        if (!ima_initialized || !S_ISREG(inode->i_mode))
-                return;
-        iint = ima_iint_find_get(inode);
-        if (!iint)
-                return;
-        mutex_lock(&iint->mutex);
-        ima_inc_counts(iint, file->f_mode);
-        mutex_unlock(&iint->mutex);
-
-        kref_put(&iint->refcount, iint_free);
-}
-EXPORT_SYMBOL_GPL(ima_counts_get);
-
 /**
  * ima_file_mmap - based on policy, collect/store measurement.
  * @file: pointer to the file to be measured (May be NULL)
@@ -369,6 +296,27 @@ int ima_bprm_check(struct linux_binprm *bprm)
         return 0;
 }
 
+/**
+ * ima_path_check - based on policy, collect/store measurement.
+ * @file: pointer to the file to be measured
+ * @mask: contains MAY_READ, MAY_WRITE or MAY_EXECUTE
+ *
+ * Measure files based on the ima_must_measure() policy decision.
+ *
+ * Always return 0 and audit dentry_open failures.
+ * (Return code will be based upon measurement appraisal.)
+ */
+int ima_path_check(struct file *file, int mask)
+{
+        int rc;
+
+        rc = process_measurement(file, file->f_dentry->d_name.name,
+                                 mask & (MAY_READ | MAY_WRITE | MAY_EXEC),
+                                 PATH_CHECK);
+        return 0;
+}
+EXPORT_SYMBOL_GPL(ima_path_check);
+
 static int __init init_ima(void)
 {
         int error;