[PATCH 1/1] file caps: update selinux xattr hooks (v4)

[Serge E . Hallyn]

SELinux does not call out to its secondary module for setxattr
or removexattr mediation, as the secondary module would
incorrectly prevent writing of selinux xattrs.  This means
that when selinux and capability are both loaded, admins will
be able to write file capabilities with CAP_SYS_ADMIN as before,
not with CAP_SETFCAP.

Update the selinux hooks to hardcode logic for the special
consideration for file caps.  Also consolidate the handling
of non-selinux xattrs in removexattr and setxattr.

Signed-off-by: Serge E. Hallyn <serue@xxxxxxxxxx>
---
 security/selinux/hooks.c |   50 +++++++++++++++++++++------------------------
 1 files changed, 23 insertions(+), 27 deletions(-)

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index af42820..54e8a47 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -2289,6 +2289,25 @@ static int selinux_inode_getattr(struct vfsmount *mnt, struct dentry *dentry)
 	return dentry_has_perm(current, mnt, dentry, FILE__GETATTR);
 }
 
+static int selinux_inode_setotherxattr(struct dentry *dentry, char *name)
+{
+	if (!strncmp(name, XATTR_SECURITY_PREFIX,
+		     sizeof XATTR_SECURITY_PREFIX - 1)) {
+		if (!strcmp(name, XATTR_NAME_CAPS)) {
+			if (!capable(CAP_SETFCAP))
+				return -EPERM;
+		} else if (!capable(CAP_SYS_ADMIN)) {
+			/* A different attribute in the security namespace.
+			   Restrict to administrator. */
+			return -EPERM;
+		}
+	}
+
+	/* Not an attribute we recognize, so just check the
+	   ordinary setattr permission. */
+	return dentry_has_perm(current, NULL, dentry, FILE__SETATTR);
+}
+
 static int selinux_inode_setxattr(struct dentry *dentry, char *name, void *value, size_t size, int flags)
 {
 	struct task_security_struct *tsec = current->security;
@@ -2299,19 +2318,8 @@ static int selinux_inode_setxattr(struct dentry *dentry, char *name, void *value
 	u32 newsid;
 	int rc = 0;
 
-	if (strcmp(name, XATTR_NAME_SELINUX)) {
-		if (!strncmp(name, XATTR_SECURITY_PREFIX,
-			     sizeof XATTR_SECURITY_PREFIX - 1) &&
-		    !capable(CAP_SYS_ADMIN)) {
-			/* A different attribute in the security namespace.
-			   Restrict to administrator. */
-			return -EPERM;
-		}
-
-		/* Not an attribute we recognize, so just check the
-		   ordinary setattr permission. */
-		return dentry_has_perm(current, NULL, dentry, FILE__SETATTR);
-	}
+	if (strcmp(name, XATTR_NAME_SELINUX))
+		return selinux_inode_setotherxattr(dentry, name);
 
 	sbsec = inode->i_sb->s_security;
 	if (sbsec->behavior == SECURITY_FS_USE_MNTPOINT)
@@ -2385,20 +2393,8 @@ static int selinux_inode_listxattr (struct dentry *dentry)
 
 static int selinux_inode_removexattr (struct dentry *dentry, char *name)
 {
-	if (strcmp(name, XATTR_NAME_SELINUX)) {
-		if (!strncmp(name, XATTR_SECURITY_PREFIX,
-			     sizeof XATTR_SECURITY_PREFIX - 1) &&
-		    !capable(CAP_SYS_ADMIN)) {
-			/* A different attribute in the security namespace.
-			   Restrict to administrator. */
-			return -EPERM;
-		}
-
-		/* Not an attribute we recognize, so just check the
-		   ordinary setattr permission. Might want a separate
-		   permission for removexattr. */
-		return dentry_has_perm(current, NULL, dentry, FILE__SETATTR);
-	}
+	if (strcmp(name, XATTR_NAME_SELINUX))
+		return selinux_inode_setotherxattr(dentry, name);
 
 	/* No one is allowed to remove a SELinux security label.
 	   You can change the label, but all data must be labeled. */
-- 
1.5.1.1.GIT

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