TOMOYO: Allow using argv[]/envp[] of execve() as conditions.

This patch adds support for permission checks using argv[]/envp[] of execve()
request. Hooks are in the last patch of this pathset.

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

1 files changed, 46 insertions, 0 deletions

diff --git a/security/tomoyo/domain.c b/security/tomoyo/domain.c
index 0f02c7852090..565249c42e39 100644
--- a/security/tomoyo/domain.c
+++ b/security/tomoyo/domain.c
@@ -713,3 +713,49 @@ int tomoyo_find_next_domain(struct linux_binprm *bprm)
 	kfree(tmp);
 	return retval;
 }
+
+/**
+ * tomoyo_dump_page - Dump a page to buffer.
+ *
+ * @bprm: Pointer to "struct linux_binprm".
+ * @pos:  Location to dump.
+ * @dump: Poiner to "struct tomoyo_page_dump".
+ *
+ * Returns true on success, false otherwise.
+ */
+bool tomoyo_dump_page(struct linux_binprm *bprm, unsigned long pos,
+		      struct tomoyo_page_dump *dump)
+{
+	struct page *page;
+	/* dump->data is released by tomoyo_finish_execve(). */
+	if (!dump->data) {
+		dump->data = kzalloc(PAGE_SIZE, GFP_NOFS);
+		if (!dump->data)
+			return false;
+	}
+	/* Same with get_arg_page(bprm, pos, 0) in fs/exec.c */
+#ifdef CONFIG_MMU
+	if (get_user_pages(current, bprm->mm, pos, 1, 0, 1, &page, NULL) <= 0)
+		return false;
+#else
+	page = bprm->page[pos / PAGE_SIZE];
+#endif
+	if (page != dump->page) {
+		const unsigned int offset = pos % PAGE_SIZE;
+		/*
+		 * Maybe kmap()/kunmap() should be used here.
+		 * But remove_arg_zero() uses kmap_atomic()/kunmap_atomic().
+		 * So do I.
+		 */
+		char *kaddr = kmap_atomic(page, KM_USER0);
+		dump->page = page;
+		memcpy(dump->data + offset, kaddr + offset,
+		       PAGE_SIZE - offset);
+		kunmap_atomic(kaddr, KM_USER0);
+	}
+	/* Same with put_arg_page(page) in fs/exec.c */
+#ifdef CONFIG_MMU
+	put_page(page);
+#endif
+	return true;
+}