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From: Kees Cook <keescook@chromium.org>
To: James Morris <jmorris@namei.org>
Cc: Kees Cook <keescook@chromium.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Joe Perches <joe@perches.com>, Mimi Zohar <zohar@linux.vnet.ibm.com>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        "Serge E. Hallyn" <serge@hallyn.com>,
        Kalle Valo <kvalo@codeaurora.org>,
        Mauro Carvalho Chehab <mchehab@osg.samsung.com>,
        Guenter Roeck <linux@roeck-us.net>, Jiri Slaby <jslaby@suse.com>,
        Paul Moore <pmoore@redhat.com>, Stephen Smalley <sds@tycho.nsa.gov>,
        Casey Schaufler <casey@schaufler-ca.com>,
        Andreas Gruenbacher <agruenba@redhat.com>,
        Rasmus Villemoes <linux@rasmusvillemoes.dk>,
        Ulf Hansson <ulf.hansson@linaro.org>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v3 3/6] string_helpers: add kstrdup_quotable_file
Date: Wed,  6 Apr 2016 17:20:34 -0700
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Content-Length: 2219
Lines: 79

Allocate a NULL-terminated file path with special characters escaped,
safe for logging.

Signed-off-by: Kees Cook <keescook@chromium.org>
---
v3:
- add gfp_t, joe
---
 include/linux/string_helpers.h |  3 +++
 lib/string_helpers.c           | 30 ++++++++++++++++++++++++++++++
 2 files changed, 33 insertions(+)

diff --git a/include/linux/string_helpers.h b/include/linux/string_helpers.h
index 82b3e37b9049..453378b1f58f 100644
--- a/include/linux/string_helpers.h
+++ b/include/linux/string_helpers.h
@@ -3,6 +3,8 @@
 
 #include <linux/types.h>
 
+struct file;
+
 /* Descriptions of the types of units to
  * print in */
 enum string_size_units {
@@ -70,5 +72,6 @@ static inline int string_escape_str_any_np(const char *src, char *dst,
 
 char *kstrdup_quotable(char *src, gfp_t gfp);
 char *kstrdup_quotable_cmdline(struct task_struct *task, gfp_t gfp);
+char *kstrdup_quotable_file(struct file *file, gfp_t gfp);
 
 #endif
diff --git a/lib/string_helpers.c b/lib/string_helpers.c
index 54fc860674db..a1cbb109b1a6 100644
--- a/lib/string_helpers.c
+++ b/lib/string_helpers.c
@@ -10,6 +10,8 @@
 #include <linux/export.h>
 #include <linux/ctype.h>
 #include <linux/errno.h>
+#include <linux/fs.h>
+#include <linux/limits.h>
 #include <linux/mm.h>
 #include <linux/slab.h>
 #include <linux/string.h>
@@ -596,3 +598,31 @@ char *kstrdup_quotable_cmdline(struct task_struct *task, gfp_t gfp)
 	return quoted;
 }
 EXPORT_SYMBOL_GPL(kstrdup_quotable_cmdline);
+
+/*
+ * Returns allocated NULL-terminated string containing pathname,
+ * with special characters escaped, able to be safely logged. If
+ * there is an error, the leading character will be "<".
+ */
+char *kstrdup_quotable_file(struct file *file, gfp_t gfp)
+{
+	char *temp, *pathname;
+
+	if (!file)
+		return kstrdup("<unknown>", gfp);
+
+	/* We add 11 spaces for ' (deleted)' to be appended */
+	temp = kmalloc(PATH_MAX + 11, GFP_TEMPORARY);
+	if (!temp)
+		return kstrdup("<no_memory>", gfp);
+
+	pathname = file_path(file, temp, PATH_MAX + 11);
+	if (IS_ERR(pathname))
+		pathname = kstrdup("<too_long>", gfp);
+	else
+		pathname = kstrdup_quotable(pathname, gfp);
+
+	kfree(temp);
+	return pathname;
+}
+EXPORT_SYMBOL_GPL(kstrdup_quotable_file);
-- 
2.6.3