file caps: always start with clear bprm->caps_*

(Sorry, resending as I seemed to have dropped lkml from the headers on yesterday's post)

From: Serge Hallyn <[email protected]>
Date: Thu, 30 Oct 2008 11:52:23 -0500
Subject: [PATCH 1/1] file caps: always start with clear bprm->caps_*

While Linux doesn't honor setuid on scripts. However, it mistakenly behaves differently for file capabilities.

This patch fixes that behavior by making sure that get_file_caps() begins with empty bprm->caps_*. That way when a script is loaded, its bprm->caps_* may be filled when binfmt_misc calls prepare_binprm(), but they will be cleared again when binfmt_elf calls prepare_binprm() next to read the interpreter's file capabilities.

---
 security/commoncap.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

index 399bfdb..3976613 100644
@@ -279,10 +279,10 @@ static int get_file_caps(struct linux_binprm *bprm)
 	struct vfs_cap_data vcaps;
 	struct inode *inode;
 
-	if (bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID) {
-		bprm_clear_caps(bprm);
+	bprm_clear_caps(bprm);
+
+	if (bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID)
 		return 0;
-	}
 
 	dentry = dget(bprm->file->f_dentry);
 	inode = dentry->d_inode;

1.5.6.3