introduce cloning of fs_context

new primitive: vfs_dup_fs_context().  Comes with fs_context
method (->dup()) for copying the filesystem-specific parts
of fs_context, along with LSM one (->fs_context_dup()) for
doing the same to LSM parts.

[needs better commit message, and change of Author:, anyway]

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 39 insertions, 0 deletions

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index f99381e97d73..4ba83de5fa80 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -2764,6 +2764,44 @@ static int selinux_umount(struct vfsmount *mnt, int flags)
                                    FILESYSTEM__UNMOUNT, NULL);
 }
 
+static int selinux_fs_context_dup(struct fs_context *fc,
+                                  struct fs_context *src_fc)
+{
+        const struct selinux_mnt_opts *src = src_fc->security;
+        struct selinux_mnt_opts *opts;
+
+        if (!src)
+                return 0;
+
+        fc->security = kzalloc(sizeof(struct selinux_mnt_opts), GFP_KERNEL);
+        if (!fc->security)
+                return -ENOMEM;
+
+        opts = fc->security;
+
+        if (src->fscontext) {
+                opts->fscontext = kstrdup(src->fscontext, GFP_KERNEL);
+                if (!opts->fscontext)
+                        return -ENOMEM;
+        }
+        if (src->context) {
+                opts->context = kstrdup(src->context, GFP_KERNEL);
+                if (!opts->context)
+                        return -ENOMEM;
+        }
+        if (src->rootcontext) {
+                opts->rootcontext = kstrdup(src->rootcontext, GFP_KERNEL);
+                if (!opts->rootcontext)
+                        return -ENOMEM;
+        }
+        if (src->defcontext) {
+                opts->defcontext = kstrdup(src->defcontext, GFP_KERNEL);
+                if (!opts->defcontext)
+                        return -ENOMEM;
+        }
+        return 0;
+}
+
 static const struct fs_parameter_spec selinux_param_specs[] = {
         fsparam_string(CONTEXT_STR,     Opt_context),
         fsparam_string(DEFCONTEXT_STR,  Opt_defcontext),
@@ -6745,6 +6783,7 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = {
         LSM_HOOK_INIT(bprm_committing_creds, selinux_bprm_committing_creds),
         LSM_HOOK_INIT(bprm_committed_creds, selinux_bprm_committed_creds),
 
+        LSM_HOOK_INIT(fs_context_dup, selinux_fs_context_dup),
         LSM_HOOK_INIT(fs_context_parse_param, selinux_fs_context_parse_param),
 
         LSM_HOOK_INIT(sb_alloc_security, selinux_sb_alloc_security),