From 0d0443288f2244d7054796086e481ddef6abdbba Mon Sep 17 00:00:00 2001
From: Kees Cook <keescook@chromium.org>
Date: Wed, 20 Apr 2016 15:46:24 -0700
Subject: [PATCH] string_helpers: add kstrdup_quotable_cmdline
Provide an escaped (but readable: no inter-argument NULLs) commandline
safe for logging.
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: James Morris <james.l.morris@oracle.com>
---
include/linux/string_helpers.h | 1 +
lib/string_helpers.c | 34 ++++++++++++++++++++++++++++++++++
2 files changed, 35 insertions(+)
diff --git a/include/linux/string_helpers.h b/include/linux/string_helpers.h
index 9de228af00c18..684d2695fc364 100644
--- a/include/linux/string_helpers.h
+++ b/include/linux/string_helpers.h
@@ -69,5 +69,6 @@ static inline int string_escape_str_any_np(const char *src, char *dst,
}
char *kstrdup_quotable(const char *src, gfp_t gfp);
+char *kstrdup_quotable_cmdline(struct task_struct *task, gfp_t gfp);
#endif
diff --git a/lib/string_helpers.c b/lib/string_helpers.c
index aa00c9f989eec..b16ee85aaf872 100644
--- a/lib/string_helpers.c
+++ b/lib/string_helpers.c
@@ -10,6 +10,7 @@
#include <linux/export.h>
#include <linux/ctype.h>
#include <linux/errno.h>
+#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/string_helpers.h>
@@ -562,3 +563,36 @@ char *kstrdup_quotable(const char *src, gfp_t gfp)
return dst;
}
EXPORT_SYMBOL_GPL(kstrdup_quotable);
+
+/*
+ * Returns allocated NULL-terminated string containing process
+ * command line, with inter-argument NULLs replaced with spaces,
+ * and other special characters escaped.
+ */
+char *kstrdup_quotable_cmdline(struct task_struct *task, gfp_t gfp)
+{
+ char *buffer, *quoted;
+ int i, res;
+
+ buffer = kmalloc(PAGE_SIZE, GFP_TEMPORARY);
+ if (!buffer)
+ return NULL;
+
+ res = get_cmdline(task, buffer, PAGE_SIZE - 1);
+ buffer[res] = '\0';
+
+ /* Collapse trailing NULLs, leave res pointing to last non-NULL. */
+ while (--res >= 0 && buffer[res] == '\0')
+ ;
+
+ /* Replace inter-argument NULLs. */
+ for (i = 0; i <= res; i++)
+ if (buffer[i] == '\0')
+ buffer[i] = ' ';
+
+ /* Make sure result is printable. */
+ quoted = kstrdup_quotable(buffer, gfp);
+ kfree(buffer);
+ return quoted;
+}
+EXPORT_SYMBOL_GPL(kstrdup_quotable_cmdline);
--
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