fanotify: introduce new event mask FAN_OPEN_EXEC_PERM

A new event mask FAN_OPEN_EXEC_PERM has been defined. This allows users
to receive events and grant access to files that are intending to be
opened for execution. Events of FAN_OPEN_EXEC_PERM type will be
generated when a file has been opened by using either execve(),
execveat() or uselib() system calls.

This acts in the same manner as previous permission event mask, meaning
that an access response is required from the user application in order
to permit any further operations on the file.

Signed-off-by: Matthew Bobrowski <mbobrowski@mbobrowski.org>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
index 5a1a15f..3723f3d 100644 (file)
--- a/fs/notify/fanotify/fanotify.c
+++ b/fs/notify/fanotify/fanotify.c
@@ -211,8 +211,9 @@ static int fanotify_handle_event(struct fsnotify_group *group,
        BUILD_BUG_ON(FAN_ACCESS_PERM != FS_ACCESS_PERM);
        BUILD_BUG_ON(FAN_ONDIR != FS_ISDIR);
        BUILD_BUG_ON(FAN_OPEN_EXEC != FS_OPEN_EXEC);
+       BUILD_BUG_ON(FAN_OPEN_EXEC_PERM != FS_OPEN_EXEC_PERM);
 
-       BUILD_BUG_ON(HWEIGHT32(ALL_FANOTIFY_EVENT_BITS) != 11);
+       BUILD_BUG_ON(HWEIGHT32(ALL_FANOTIFY_EVENT_BITS) != 12);
 
        mask = fanotify_group_event_mask(iter_info, mask, data, data_type);
        if (!mask)

diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c
index b3f58f3..ecf09b6 100644 (file)
--- a/fs/notify/fsnotify.c
+++ b/fs/notify/fsnotify.c
@@ -401,7 +401,7 @@ static __init int fsnotify_init(void)
 {
        int ret;
 
-       BUILD_BUG_ON(HWEIGHT32(ALL_FSNOTIFY_BITS) != 24);
+       BUILD_BUG_ON(HWEIGHT32(ALL_FSNOTIFY_BITS) != 25);
 
        ret = init_srcu_struct(&fsnotify_mark_srcu);
        if (ret)

diff --git a/include/linux/fanotify.h b/include/linux/fanotify.h
index c521e42..9e21427 100644 (file)
--- a/include/linux/fanotify.h
+++ b/include/linux/fanotify.h
@@ -40,7 +40,8 @@
                                 FAN_CLOSE | FAN_OPEN | FAN_OPEN_EXEC)
 
 /* Events that require a permission response from user */
-#define FANOTIFY_PERM_EVENTS   (FAN_OPEN_PERM | FAN_ACCESS_PERM)
+#define FANOTIFY_PERM_EVENTS   (FAN_OPEN_PERM | FAN_ACCESS_PERM | \
+                                FAN_OPEN_EXEC_PERM)
 
 /* Extra flags that may be reported with event or control handling of events */
 #define FANOTIFY_EVENT_FLAGS   (FAN_EVENT_ON_CHILD | FAN_ONDIR)

diff --git a/include/linux/fsnotify.h b/include/linux/fsnotify.h
index c29f2f0..2ccb08c 100644 (file)
--- a/include/linux/fsnotify.h
+++ b/include/linux/fsnotify.h
@@ -40,9 +40,10 @@ static inline int fsnotify_path(struct inode *inode, const struct path *path,
        return fsnotify(inode, mask, path, FSNOTIFY_EVENT_PATH, NULL, 0);
 }
 
-/* simple call site for access decisions */
+/* Simple call site for access decisions */
 static inline int fsnotify_perm(struct file *file, int mask)
 {
+       int ret;
        const struct path *path = &file->f_path;
        struct inode *inode = file_inode(file);
        __u32 fsnotify_mask = 0;
@@ -51,12 +52,18 @@ static inline int fsnotify_perm(struct file *file, int mask)
                return 0;
        if (!(mask & (MAY_READ | MAY_OPEN)))
                return 0;
-       if (mask & MAY_OPEN)
+       if (mask & MAY_OPEN) {
                fsnotify_mask = FS_OPEN_PERM;
-       else if (mask & MAY_READ)
+
+               if (file->f_flags & __FMODE_EXEC) {
+                       ret = fsnotify_path(inode, path, FS_OPEN_EXEC_PERM);
+
+                       if (ret)
+                               return ret;
+               }
+       } else if (mask & MAY_READ) {
                fsnotify_mask = FS_ACCESS_PERM;
-       else
-               BUG();
+       }
 
        return fsnotify_path(inode, path, fsnotify_mask);
 }

diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index 39d94e6..7639774 100644 (file)
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -46,6 +46,7 @@
 
 #define FS_OPEN_PERM           0x00010000      /* open event in an permission hook */
 #define FS_ACCESS_PERM         0x00020000      /* access event in a permissions hook */
+#define FS_OPEN_EXEC_PERM      0x00040000      /* open/exec event in a permission hook */
 
 #define FS_EXCL_UNLINK         0x04000000      /* do not send events if object is unlinked */
 #define FS_ISDIR               0x40000000      /* event occurred against dir */
@@ -64,11 +65,12 @@
                                   FS_CLOSE_WRITE | FS_CLOSE_NOWRITE | FS_OPEN |\
                                   FS_MOVED_FROM | FS_MOVED_TO | FS_CREATE |\
                                   FS_DELETE | FS_OPEN_PERM | FS_ACCESS_PERM | \
-                                  FS_OPEN_EXEC)
+                                  FS_OPEN_EXEC | FS_OPEN_EXEC_PERM)
 
 #define FS_MOVE                        (FS_MOVED_FROM | FS_MOVED_TO)
 
-#define ALL_FSNOTIFY_PERM_EVENTS (FS_OPEN_PERM | FS_ACCESS_PERM)
+#define ALL_FSNOTIFY_PERM_EVENTS (FS_OPEN_PERM | FS_ACCESS_PERM | \
+                                 FS_OPEN_EXEC_PERM)
 
 /* Events that can be reported to backends */
 #define ALL_FSNOTIFY_EVENTS (FS_ACCESS | FS_MODIFY | FS_ATTRIB | \
@@ -77,7 +79,7 @@
                             FS_DELETE | FS_DELETE_SELF | FS_MOVE_SELF | \
                             FS_UNMOUNT | FS_Q_OVERFLOW | FS_IN_IGNORED | \
                             FS_OPEN_PERM | FS_ACCESS_PERM | FS_DN_RENAME | \
-                            FS_OPEN_EXEC)
+                            FS_OPEN_EXEC | FS_OPEN_EXEC_PERM)
 
 /* Extra flags that may be reported with event or control handling of events */
 #define ALL_FSNOTIFY_FLAGS  (FS_EXCL_UNLINK | FS_ISDIR | FS_IN_ONESHOT | \

diff --git a/include/uapi/linux/fanotify.h b/include/uapi/linux/fanotify.h
index d9664fb..909c98f 100644 (file)
--- a/include/uapi/linux/fanotify.h
+++ b/include/uapi/linux/fanotify.h
@@ -16,6 +16,7 @@
 
 #define FAN_OPEN_PERM          0x00010000      /* File open in perm check */
 #define FAN_ACCESS_PERM                0x00020000      /* File accessed in perm check */
+#define FAN_OPEN_EXEC_PERM     0x00040000      /* File open/exec in perm check */
 
 #define FAN_ONDIR              0x40000000      /* event occurred against dir */