revert "capabilities: clean up file capability reading"

Revert b68680e4731abbd78863063aaa0dca2a6d8cc723 to make way for the next
patch: "Add 64-bit capability support to the kernel".

We want to keep the vfs_cap_data.data[] structure, using two 'data's for
64-bit caps (and later three for 96-bit caps), whereas
b68680e4731abbd78863063aaa0dca2a6d8cc723 had gotten rid of the 'data' struct
made its members inline.

The 64-bit caps patch keeps the stack abuse fix at get_file_caps(), which was
the more important part of that patch.

[akpm@linux-foundation.org: coding-style fixes]
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: Serge Hallyn <serue@us.ibm.com>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: James Morris <jmorris@namei.org>
Cc: Casey Schaufler <casey@schaufler-ca.com>
Cc: Andrew Morgan <morgan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/capability.h

@@ -56,8 +56,10 @@ typedef struct __user_cap_data_struct {
 
 struct vfs_cap_data {
 	__u32 magic_etc;  /* Little endian */
-	__u32 permitted;    /* Little endian */
-	__u32 inheritable;  /* Little endian */
+	struct {
+		__u32 permitted;    /* Little endian */
+		__u32 inheritable;  /* Little endian */
+	} data[1];
 };
 
 #ifdef __KERNEL__

security/commoncap.c

@@ -197,8 +197,7 @@ int cap_inode_killpriv(struct dentry *dentry)
 	return inode->i_op->removexattr(dentry, XATTR_NAME_CAPS);
 }
 
-static inline int cap_from_disk(struct vfs_cap_data *caps,
-				struct linux_binprm *bprm,
+static inline int cap_from_disk(__le32 *caps, struct linux_binprm *bprm,
 				int size)
 {
 	__u32 magic_etc;
@@ -206,7 +205,7 @@ static inline int cap_from_disk(struct vfs_cap_data *caps,
 	if (size != XATTR_CAPS_SZ)
 		return -EINVAL;
 
-	magic_etc = le32_to_cpu(caps->magic_etc);
+	magic_etc = le32_to_cpu(caps[0]);
 
 	switch ((magic_etc & VFS_CAP_REVISION_MASK)) {
 	case VFS_CAP_REVISION:
@@ -214,8 +213,8 @@ static inline int cap_from_disk(struct vfs_cap_data *caps,
 			bprm->cap_effective = true;
 		else
 			bprm->cap_effective = false;
-		bprm->cap_permitted = to_cap_t(le32_to_cpu(caps->permitted));
-		bprm->cap_inheritable = to_cap_t(le32_to_cpu(caps->inheritable));
+		bprm->cap_permitted = to_cap_t(le32_to_cpu(caps[1]));
+		bprm->cap_inheritable = to_cap_t(le32_to_cpu(caps[2]));
 		return 0;
 	default:
 		return -EINVAL;
@@ -227,7 +226,7 @@ static int get_file_caps(struct linux_binprm *bprm)
 {
 	struct dentry *dentry;
 	int rc = 0;
-	struct vfs_cap_data incaps;
+	__le32 v1caps[XATTR_CAPS_SZ];
 	struct inode *inode;
 
 	if (bprm->file->f_vfsmnt->mnt_flags & MNT_NOSUID) {
@@ -240,14 +239,8 @@ static int get_file_caps(struct linux_binprm *bprm)
 	if (!inode->i_op || !inode->i_op->getxattr)
 		goto out;
 
-	rc = inode->i_op->getxattr(dentry, XATTR_NAME_CAPS, NULL, 0);
-	if (rc > 0) {
-		if (rc == XATTR_CAPS_SZ)
-			rc = inode->i_op->getxattr(dentry, XATTR_NAME_CAPS,
-						&incaps, XATTR_CAPS_SZ);
-		else
-			rc = -EINVAL;
-	}
+	rc = inode->i_op->getxattr(dentry, XATTR_NAME_CAPS, &v1caps,
+							XATTR_CAPS_SZ);
 	if (rc == -ENODATA || rc == -EOPNOTSUPP) {
 		/* no data, that's ok */
 		rc = 0;
@@ -256,7 +249,7 @@ static int get_file_caps(struct linux_binprm *bprm)
 	if (rc < 0)
 		goto out;
 
-	rc = cap_from_disk(&incaps, bprm, rc);
+	rc = cap_from_disk(v1caps, bprm, rc);
 	if (rc)
 		printk(KERN_NOTICE "%s: cap_from_disk returned %d for %s\n",
 			__FUNCTION__, rc, bprm->filename);