libkmod-config: re-quote option from kernel cmdline

It was reported that grub mangles the kernel cmdline. It turns

	acpi_cpufreq.dyndbg="file drivers/cpufreq/acpi-cpufreq.c +mpf"

	into

	"acpi_cpufreq.dyndbg=file drivers/cpufreq/acpi-cpufreq.c +mpf"

However, even though we could blame grub for doing that, the kernel
happily accepts and re-quotes it when the module is built-in.
So, it's better if kmod also understands it this way and does the same.

Here we basically add additional code to un-mangle it, moving the quote
in way that is acceptable to pass through init_module(). Note that the
interface [f]init_module() gives us mandates the quote to be part of the
value: the module name is not passed and the options are separated by
space.

Reported-by: Jiri Slaby <jirislaby@kernel.org>
Tested-by: Jessica Yu <jeyu@kernel.org>
Link: https://bugzilla.suse.com/show_bug.cgi?id=1181111#c10

1 files changed, 35 insertions, 1 deletions

diff --git a/libkmod/libkmod-config.c b/libkmod/libkmod-config.c
index d3cd10d..2873f06 100644
--- a/libkmod/libkmod-config.c
+++ b/libkmod/libkmod-config.c
@@ -498,7 +498,7 @@ static int kmod_config_parse_kcmdline(struct kmod_config *config)
 {
 	char buf[KCMD_LINE_SIZE];
 	int fd, err;
-	char *p, *modname,  *param = NULL, *value = NULL;
+	char *p, *p_quote_start, *modname,  *param = NULL, *value = NULL;
 	bool is_quoted = false, iter = true;
 	enum state {
 		STATE_IGNORE,
@@ -524,10 +524,23 @@ static int kmod_config_parse_kcmdline(struct kmod_config *config)
 	}
 
 	state = STATE_MODNAME;
+	p_quote_start = NULL;
 	for (p = buf, modname = buf; iter; p++) {
 		switch (*p) {
 		case '"':
 			is_quoted = !is_quoted;
+
+			/*
+			 * only allow starting quote as first char when looking
+			 * for a modname: anything else is considered ill-formed
+			 */
+			if (is_quoted && state == STATE_MODNAME && p == modname) {
+				p_quote_start = p;
+				modname = p + 1;
+			} else if (state != STATE_VALUE) {
+				state = STATE_IGNORE;
+			}
+
 			break;
 		case '\0':
 		case '\n':
@@ -550,6 +563,7 @@ static int kmod_config_parse_kcmdline(struct kmod_config *config)
 				 */
 				modname = p + 1;
 				state = STATE_MODNAME;
+				p_quote_start = NULL;
 			}
 			break;
 		case '.':
@@ -576,10 +590,30 @@ static int kmod_config_parse_kcmdline(struct kmod_config *config)
 		}
 
 		if (state == STATE_COMPLETE) {
+			/*
+			 * We may need to re-quote to unmangle what the
+			 * bootloader passed. Example: grub passes the option as
+			 * "parport.dyndbg=file drivers/parport/ieee1284_ops.c +mpf"
+			 * instead of
+			 * parport.dyndbg="file drivers/parport/ieee1284_ops.c +mpf"
+			 */
+			if (p_quote_start && p_quote_start < modname) {
+				/*
+				 * p_quote_start
+				 * |
+				 * |modname  param  value
+				 * ||        |      |
+				 * vv        v      v
+				 * "parport\0dyndbg=file drivers/parport/ieee1284_ops.c +mpf" */
+				memmove(p_quote_start, modname, value - modname);
+				value--; modname--; param--;
+				*value = '"';
+			}
 			kcmdline_parse_result(config, modname, param, value);
 			/* start over on next iteration */
 			modname = p + 1;
 			state = STATE_MODNAME;
+			p_quote_start = NULL;
 		}
 	}