Merge tag 'selinux-pr-20190507' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux

Pull selinux updates from Paul Moore:
 "We've got a few SELinux patches for the v5.2 merge window, the
  highlights are below:

   - Add LSM hooks, and the SELinux implementation, for proper labeling
     of kernfs. While we are only including the SELinux implementation
     here, the rest of the LSM folks have given the hooks a thumbs-up.

   - Update the SELinux mdp (Make Dummy Policy) script to actually work
     on a modern system.

   - Disallow userspace to change the LSM credentials via
     /proc/self/attr when the task's credentials are already overridden.

     The change was made in procfs because all the LSM folks agreed this
     was the Right Thing To Do and duplicating it across each LSM was
     going to be annoying"

* tag 'selinux-pr-20190507' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
  proc: prevent changes to overridden credentials
  selinux: Check address length before reading address family
  kernfs: fix xattr name handling in LSM helpers
  MAINTAINERS: update SELinux file patterns
  selinux: avoid uninitialized variable warning
  selinux: remove useless assignments
  LSM: lsm_hooks.h - fix missing colon in docstring
  selinux: Make selinux_kernfs_init_security static
  kernfs: initialize security of newly created nodes
  selinux: implement the kernfs_init_security hook
  LSM: add new hook for kernfs node initialization
  kernfs: use simple_xattrs for security attributes
  selinux: try security xattr after genfs for kernfs filesystems
  kernfs: do not alloc iattrs in kernfs_xattr_get
  kernfs: clean up struct kernfs_iattrs
  scripts/selinux: fix build
  selinux: use kernel linux/socket.h for genheaders and mdp
  scripts/selinux: modernize mdp

1 files changed, 155 insertions, 74 deletions

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 1d0b37af2444..c61787b15f27 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -89,6 +89,8 @@
 #include <linux/msg.h>
 #include <linux/shm.h>
 #include <linux/bpf.h>
+#include <linux/kernfs.h>
+#include <linux/stringhash.h>   /* for hashlen_string() */
 #include <uapi/linux/mount.h>
 
 #include "avc.h"
@@ -751,11 +753,13 @@ static int selinux_set_mnt_opts(struct super_block *sb,
 
         if (!strcmp(sb->s_type->name, "debugfs") ||
             !strcmp(sb->s_type->name, "tracefs") ||
-            !strcmp(sb->s_type->name, "sysfs") ||
-            !strcmp(sb->s_type->name, "pstore") ||
+            !strcmp(sb->s_type->name, "pstore"))
+                sbsec->flags |= SE_SBGENFS;
+
+        if (!strcmp(sb->s_type->name, "sysfs") ||
             !strcmp(sb->s_type->name, "cgroup") ||
             !strcmp(sb->s_type->name, "cgroup2"))
-                sbsec->flags |= SE_SBGENFS;
+                sbsec->flags |= SE_SBGENFS | SE_SBGENFS_XATTR;
 
         if (!sbsec->behavior) {
                 /*
@@ -1354,6 +1358,67 @@ static int selinux_genfs_get_sid(struct dentry *dentry,
         return rc;
 }
 
+static int inode_doinit_use_xattr(struct inode *inode, struct dentry *dentry,
+                                  u32 def_sid, u32 *sid)
+{
+#define INITCONTEXTLEN 255
+        char *context;
+        unsigned int len;
+        int rc;
+
+        len = INITCONTEXTLEN;
+        context = kmalloc(len + 1, GFP_NOFS);
+        if (!context)
+                return -ENOMEM;
+
+        context[len] = '\0';
+        rc = __vfs_getxattr(dentry, inode, XATTR_NAME_SELINUX, context, len);
+        if (rc == -ERANGE) {
+                kfree(context);
+
+                /* Need a larger buffer.  Query for the right size. */
+                rc = __vfs_getxattr(dentry, inode, XATTR_NAME_SELINUX, NULL, 0);
+                if (rc < 0)
+                        return rc;
+
+                len = rc;
+                context = kmalloc(len + 1, GFP_NOFS);
+                if (!context)
+                        return -ENOMEM;
+
+                context[len] = '\0';
+                rc = __vfs_getxattr(dentry, inode, XATTR_NAME_SELINUX,
+                                    context, len);
+        }
+        if (rc < 0) {
+                kfree(context);
+                if (rc != -ENODATA) {
+                        pr_warn("SELinux: %s:  getxattr returned %d for dev=%s ino=%ld\n",
+                                __func__, -rc, inode->i_sb->s_id, inode->i_ino);
+                        return rc;
+                }
+                *sid = def_sid;
+                return 0;
+        }
+
+        rc = security_context_to_sid_default(&selinux_state, context, rc, sid,
+                                             def_sid, GFP_NOFS);
+        if (rc) {
+                char *dev = inode->i_sb->s_id;
+                unsigned long ino = inode->i_ino;
+
+                if (rc == -EINVAL) {
+                        pr_notice_ratelimited("SELinux: inode=%lu on dev=%s was found to have an invalid context=%s.  This indicates you may need to relabel the inode or the filesystem in question.\n",
+                                              ino, dev, context);
+                } else {
+                        pr_warn("SELinux: %s:  context_to_sid(%s) returned %d for dev=%s ino=%ld\n",
+                                __func__, context, -rc, dev, ino);
+                }
+        }
+        kfree(context);
+        return 0;
+}
+
 /* The inode's security attributes must be initialized before first use. */
 static int inode_doinit_with_dentry(struct inode *inode, struct dentry *opt_dentry)
 {
@@ -1362,9 +1427,6 @@ static int inode_doinit_with_dentry(struct inode *inode, struct dentry *opt_dent
         u32 task_sid, sid = 0;
         u16 sclass;
         struct dentry *dentry;
-#define INITCONTEXTLEN 255
-        char *context = NULL;
-        unsigned len = 0;
         int rc = 0;
 
         if (isec->initialized == LABEL_INITIALIZED)
@@ -1432,72 +1494,11 @@ static int inode_doinit_with_dentry(struct inode *inode, struct dentry *opt_dent
                         goto out;
                 }
 
-                len = INITCONTEXTLEN;
-                context = kmalloc(len+1, GFP_NOFS);
-                if (!context) {
-                        rc = -ENOMEM;
-                        dput(dentry);
-                        goto out;
-                }
-                context[len] = '\0';
-                rc = __vfs_getxattr(dentry, inode, XATTR_NAME_SELINUX, context, len);
-                if (rc == -ERANGE) {
-                        kfree(context);
-
-                        /* Need a larger buffer.  Query for the right size. */
-                        rc = __vfs_getxattr(dentry, inode, XATTR_NAME_SELINUX, NULL, 0);
-                        if (rc < 0) {
-                                dput(dentry);
-                                goto out;
-                        }
-                        len = rc;
-                        context = kmalloc(len+1, GFP_NOFS);
-                        if (!context) {
-                                rc = -ENOMEM;
-                                dput(dentry);
-                                goto out;
-                        }
-                        context[len] = '\0';
-                        rc = __vfs_getxattr(dentry, inode, XATTR_NAME_SELINUX, context, len);
-                }
+                rc = inode_doinit_use_xattr(inode, dentry, sbsec->def_sid,
+                                            &sid);
                 dput(dentry);
-                if (rc < 0) {
-                        if (rc != -ENODATA) {
-                                pr_warn("SELinux: %s:  getxattr returned "
-                                       "%d for dev=%s ino=%ld\n", __func__,
-                                       -rc, inode->i_sb->s_id, inode->i_ino);
-                                kfree(context);
-                                goto out;
-                        }
-                        /* Map ENODATA to the default file SID */
-                        sid = sbsec->def_sid;
-                        rc = 0;
-                } else {
-                        rc = security_context_to_sid_default(&selinux_state,
-                                                             context, rc, &sid,
-                                                             sbsec->def_sid,
-                                                             GFP_NOFS);
-                        if (rc) {
-                                char *dev = inode->i_sb->s_id;
-                                unsigned long ino = inode->i_ino;
-
-                                if (rc == -EINVAL) {
-                                        if (printk_ratelimit())
-                                                pr_notice("SELinux: inode=%lu on dev=%s was found to have an invalid "
-                                                        "context=%s.  This indicates you may need to relabel the inode or the "
-                                                        "filesystem in question.\n", ino, dev, context);
-                                } else {
-                                        pr_warn("SELinux: %s:  context_to_sid(%s) "
-                                               "returned %d for dev=%s ino=%ld\n",
-                                               __func__, context, -rc, dev, ino);
-                                }
-                                kfree(context);
-                                /* Leave with the unlabeled SID */
-                                rc = 0;
-                                break;
-                        }
-                }
-                kfree(context);
+                if (rc)
+                        goto out;
                 break;
         case SECURITY_FS_USE_TASK:
                 sid = task_sid;
@@ -1548,9 +1549,21 @@ static int inode_doinit_with_dentry(struct inode *inode, struct dentry *opt_dent
                                 goto out;
                         rc = selinux_genfs_get_sid(dentry, sclass,
                                                    sbsec->flags, &sid);
-                        dput(dentry);
-                        if (rc)
+                        if (rc) {
+                                dput(dentry);
                                 goto out;
+                        }
+
+                        if ((sbsec->flags & SE_SBGENFS_XATTR) &&
+                            (inode->i_opflags & IOP_XATTR)) {
+                                rc = inode_doinit_use_xattr(inode, dentry,
+                                                            sid, &sid);
+                                if (rc) {
+                                        dput(dentry);
+                                        goto out;
+                                }
+                        }
+                        dput(dentry);
                 }
                 break;
         }
@@ -3371,6 +3384,67 @@ static int selinux_inode_copy_up_xattr(const char *name)
         return -EOPNOTSUPP;
 }
 
+/* kernfs node operations */
+
+static int selinux_kernfs_init_security(struct kernfs_node *kn_dir,
+                                        struct kernfs_node *kn)
+{
+        const struct task_security_struct *tsec = current_security();
+        u32 parent_sid, newsid, clen;
+        int rc;
+        char *context;
+
+        rc = kernfs_xattr_get(kn_dir, XATTR_NAME_SELINUX, NULL, 0);
+        if (rc == -ENODATA)
+                return 0;
+        else if (rc < 0)
+                return rc;
+
+        clen = (u32)rc;
+        context = kmalloc(clen, GFP_KERNEL);
+        if (!context)
+                return -ENOMEM;
+
+        rc = kernfs_xattr_get(kn_dir, XATTR_NAME_SELINUX, context, clen);
+        if (rc < 0) {
+                kfree(context);
+                return rc;
+        }
+
+        rc = security_context_to_sid(&selinux_state, context, clen, &parent_sid,
+                                     GFP_KERNEL);
+        kfree(context);
+        if (rc)
+                return rc;
+
+        if (tsec->create_sid) {
+                newsid = tsec->create_sid;
+        } else {
+                u16 secclass = inode_mode_to_security_class(kn->mode);
+                struct qstr q;
+
+                q.name = kn->name;
+                q.hash_len = hashlen_string(kn_dir, kn->name);
+
+                rc = security_transition_sid(&selinux_state, tsec->sid,
+                                             parent_sid, secclass, &q,
+                                             &newsid);
+                if (rc)
+                        return rc;
+        }
+
+        rc = security_sid_to_context_force(&selinux_state, newsid,
+                                           &context, &clen);
+        if (rc)
+                return rc;
+
+        rc = kernfs_xattr_set(kn, XATTR_NAME_SELINUX, context, clen,
+                              XATTR_CREATE);
+        kfree(context);
+        return rc;
+}
+
+
 /* file security operations */
 
 static int selinux_revalidate_file_permission(struct file *file, int mask)
@@ -4438,7 +4512,7 @@ static int selinux_socket_bind(struct socket *sock, struct sockaddr *address, in
                 struct lsm_network_audit net = {0,};
                 struct sockaddr_in *addr4 = NULL;
                 struct sockaddr_in6 *addr6 = NULL;
-                u16 family_sa = address->sa_family;
+                u16 family_sa;
                 unsigned short snum;
                 u32 sid, node_perm;
 
@@ -4448,6 +4522,9 @@ static int selinux_socket_bind(struct socket *sock, struct sockaddr *address, in
                  * need to check address->sa_family as it is possible to have
                  * sk->sk_family = PF_INET6 with addr->sa_family = AF_INET.
                  */
+                if (addrlen < offsetofend(struct sockaddr, sa_family))
+                        return -EINVAL;
+                family_sa = address->sa_family;
                 switch (family_sa) {
                 case AF_UNSPEC:
                 case AF_INET:
@@ -4580,6 +4657,8 @@ static int selinux_socket_connect_helper(struct socket *sock,
                  * need to check address->sa_family as it is possible to have
                  * sk->sk_family = PF_INET6 with addr->sa_family = AF_INET.
                  */
+                if (addrlen < offsetofend(struct sockaddr, sa_family))
+                        return -EINVAL;
                 switch (address->sa_family) {
                 case AF_INET:
                         addr4 = (struct sockaddr_in *)address;
@@ -6719,6 +6798,8 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
         LSM_HOOK_INIT(inode_copy_up, selinux_inode_copy_up),
         LSM_HOOK_INIT(inode_copy_up_xattr, selinux_inode_copy_up_xattr),
 
+        LSM_HOOK_INIT(kernfs_init_security, selinux_kernfs_init_security),
+
         LSM_HOOK_INIT(file_permission, selinux_file_permission),
         LSM_HOOK_INIT(file_alloc_security, selinux_file_alloc_security),
         LSM_HOOK_INIT(file_ioctl, selinux_file_ioctl),