[dm-devel] [PATCH 3/3] libmutipath: validate the argument count of config strings

[Benjamin Marzinski <bmarzins@redhat.com>]

The features, path_selector, and hardware_handler config options pass
their strings directly into the kernel.  If users omit the argument
counts from these strings, or use the wrong value, the kernel's table
parsing gets completely messed up, and the error messages it prints
don't reflect what actully went wrong. To avoid messing up the
kernel table parsing, verify that these strings correctly set the
argument count to the number of arguments they have.

Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
---
 libmultipath/dict.c | 110 ++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 101 insertions(+), 9 deletions(-)

diff --git a/libmultipath/dict.c b/libmultipath/dict.c
index f4233882..6645de49 100644
--- a/libmultipath/dict.c
+++ b/libmultipath/dict.c
@@ -116,6 +116,58 @@ set_str(vector strvec, void *ptr, const char *file, int line_nr)
 	return 0;
 }
 
+static int
+set_arg_str(vector strvec, void *ptr, int count_idx, const char *file,
+	    int line_nr)
+{
+	char **str_ptr = (char **)ptr;
+	char *old_str = *str_ptr;
+	const char *spaces = " \f\n\r\t\v";
+	char *p, *end;
+	int idx = -1;
+	long int count = -1;
+
+	*str_ptr = set_value(strvec);
+	if (!*str_ptr) {
+		free(old_str);
+		return 1;
+	}
+	p = *str_ptr;
+	while (*p != '\0') {
+		p += strspn(p, spaces);
+		if (*p == '\0')
+			break;
+		idx += 1;
+		if (idx == count_idx) {
+			errno = 0;
+			count = strtol(p, &end, 10);
+			if (errno == ERANGE || end == p ||
+			    !(isspace(*end) || *end == '\0')) {
+				count = -1;
+				break;
+			}
+		}
+		p += strcspn(p, spaces);
+	}
+	if (count < 0) {
+		condlog(1, "%s line %d, missing argument count for %s",
+			file, line_nr, (char*)VECTOR_SLOT(strvec, 0));
+		goto fail;
+	}
+	if (count != idx - count_idx) {
+		condlog(1, "%s line %d, invalid argument count for %s:, got '%ld' expected '%d'",
+			file, line_nr, (char*)VECTOR_SLOT(strvec, 0), count,
+			idx - count_idx);
+		goto fail;
+	}
+	free(old_str);
+	return 0;
+fail:
+	free(*str_ptr);
+	*str_ptr = old_str;
+	return 0;
+}
+
 static int
 set_path(vector strvec, void *ptr, const char *file, int line_nr)
 {
@@ -288,6 +340,14 @@ def_ ## option ## _handler (struct config *conf, vector strvec,         \
 	return set_int(strvec, &conf->option, minval, maxval, file, line_nr); \
 }
 
+#define declare_def_arg_str_handler(option, count_idx)			\
+static int								\
+def_ ## option ## _handler (struct config *conf, vector strvec,		\
+			    const char *file, int line_nr)		\
+{									\
+	return set_arg_str(strvec, &conf->option, count_idx, file, line_nr); \
+}
+
 #define declare_def_snprint(option, function)				\
 static int								\
 snprint_def_ ## option (struct config *conf, struct strbuf *buff,	\
@@ -340,6 +400,17 @@ hw_ ## option ## _handler (struct config *conf, vector strvec,		\
 	return set_int(strvec, &hwe->option, minval, maxval, file, line_nr); \
 }
 
+#define declare_hw_arg_str_handler(option, count_idx)			\
+static int								\
+hw_ ## option ## _handler (struct config *conf, vector strvec,		\
+			    const char *file, int line_nr)		\
+{									\
+	struct hwentry * hwe = VECTOR_LAST_SLOT(conf->hwtable);		\
+	if (!hwe)							\
+		return 1;						\
+	return set_arg_str(strvec, &hwe->option, count_idx, file, line_nr); \
+}
+
 
 #define declare_hw_snprint(option, function)				\
 static int								\
@@ -371,6 +442,16 @@ ovr_ ## option ## _handler (struct config *conf, vector strvec,		\
 		       file, line_nr); \
 }
 
+#define declare_ovr_arg_str_handler(option, count_idx)			\
+static int								\
+ovr_ ## option ## _handler (struct config *conf, vector strvec,		\
+			    const char *file, int line_nr)		\
+{									\
+	if (!conf->overrides)						\
+		return 1;						\
+	return set_arg_str(strvec, &conf->overrides->option, count_idx, file, line_nr); \
+}
+
 #define declare_ovr_snprint(option, function)				\
 static int								\
 snprint_ovr_ ## option (struct config *conf, struct strbuf *buff,	\
@@ -401,6 +482,17 @@ mp_ ## option ## _handler (struct config *conf, vector strvec,		\
 	return set_int(strvec, &mpe->option, minval, maxval, file, line_nr); \
 }
 
+#define declare_mp_arg_str_handler(option, count_idx)			\
+static int								\
+mp_ ## option ## _handler (struct config *conf, vector strvec,		\
+			    const char *file, int line_nr)		\
+{									\
+	struct mpentry * mpe = VECTOR_LAST_SLOT(conf->mptable);		\
+	if (!mpe)							\
+		return 1;						\
+	return set_arg_str(strvec, &mpe->option, count_idx, file, line_nr); \
+}
+
 #define declare_mp_snprint(option, function)				\
 static int								\
 snprint_mp_ ## option (struct config *conf, struct strbuf *buff,	\
@@ -584,13 +676,13 @@ snprint_def_marginal_pathgroups(struct config *conf, struct strbuf *buff,
 }
 
 
-declare_def_handler(selector, set_str)
+declare_def_arg_str_handler(selector, 1)
 declare_def_snprint_defstr(selector, print_str, DEFAULT_SELECTOR)
-declare_hw_handler(selector, set_str)
+declare_hw_arg_str_handler(selector, 1)
 declare_hw_snprint(selector, print_str)
-declare_ovr_handler(selector, set_str)
+declare_ovr_arg_str_handler(selector, 1)
 declare_ovr_snprint(selector, print_str)
-declare_mp_handler(selector, set_str)
+declare_mp_arg_str_handler(selector, 1)
 declare_mp_snprint(selector, print_str)
 
 static int snprint_uid_attrs(struct config *conf, struct strbuf *buff,
@@ -663,13 +755,13 @@ declare_hw_snprint(prio_args, print_str)
 declare_mp_handler(prio_args, set_str)
 declare_mp_snprint(prio_args, print_str)
 
-declare_def_handler(features, set_str)
+declare_def_arg_str_handler(features, 0)
 declare_def_snprint_defstr(features, print_str, DEFAULT_FEATURES)
-declare_ovr_handler(features, set_str)
+declare_ovr_arg_str_handler(features, 0)
 declare_ovr_snprint(features, print_str)
-declare_hw_handler(features, set_str)
+declare_hw_arg_str_handler(features, 0)
 declare_hw_snprint(features, print_str)
-declare_mp_handler(features, set_str)
+declare_mp_arg_str_handler(features, 0)
 declare_mp_snprint(features, print_str)
 
 declare_def_handler(checker_name, set_str)
@@ -1821,7 +1913,7 @@ declare_hw_snprint(revision, print_str)
 declare_hw_handler(bl_product, set_str)
 declare_hw_snprint(bl_product, print_str)
 
-declare_hw_handler(hwhandler, set_str)
+declare_hw_arg_str_handler(hwhandler, 0)
 declare_hw_snprint(hwhandler, print_str)
 
 /*
-- 
2.17.2

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