TOMOYO: Add environment variable name restriction support.

This patch adds support for checking environment variable's names.
Although TOMOYO already provides ability to check argv[]/envp[] passed to
execve() requests,

  file execute /bin/sh exec.envp["LD_LIBRARY_PATH"]="bar"

will reject execution of /bin/sh if environment variable LD_LIBRARY_PATH is not
defined. To grant execution of /bin/sh if LD_LIBRARY_PATH is not defined,
administrators have to specify like

  file execute /bin/sh exec.envp["LD_LIBRARY_PATH"]="/system/lib"
  file execute /bin/sh exec.envp["LD_LIBRARY_PATH"]=NULL

. Since there are many environment variables whereas conditional checks are
applied as "&&", it is difficult to cover all combinations. Therefore, this
patch supports conditional checks that are applied as "||", by specifying like

  file execute /bin/sh
  misc env LD_LIBRARY_PATH exec.envp["LD_LIBRARY_PATH"]="/system/lib"

which means "grant execution of /bin/sh if environment variable is not defined
or is defined and its value is /system/lib".

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: James Morris <jmorris@namei.org>

1 files changed, 9 insertions, 0 deletions

diff --git a/security/tomoyo/gc.c b/security/tomoyo/gc.c
index 5295b5caaa21..818b07998111 100644
--- a/security/tomoyo/gc.c
+++ b/security/tomoyo/gc.c
@@ -36,6 +36,7 @@ static const u8 tomoyo_acl_size[] = {
 	[TOMOYO_TYPE_PATH_NUMBER_ACL] = sizeof(struct tomoyo_path_number_acl),
 	[TOMOYO_TYPE_MKDEV_ACL] = sizeof(struct tomoyo_mkdev_acl),
 	[TOMOYO_TYPE_MOUNT_ACL] = sizeof(struct tomoyo_mount_acl),
+	[TOMOYO_TYPE_ENV_ACL] = sizeof(struct tomoyo_env_acl),
 };
 
 /**
@@ -293,6 +294,14 @@ static void tomoyo_del_acl(struct list_head *element)
 			tomoyo_put_number_union(&entry->flags);
 		}
 		break;
+	case TOMOYO_TYPE_ENV_ACL:
+		{
+			struct tomoyo_env_acl *entry =
+				container_of(acl, typeof(*entry), head);
+
+			tomoyo_put_name(entry->env);
+		}
+		break;
 	}
 }