utils: fix task_blocking_signal()

Closes #2342.

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

src/lxc/lxccontainer.c

@@ -2008,7 +2008,7 @@ static bool do_lxcapi_shutdown(struct lxc_container *c, int timeout)
 	/* Detect whether we should send SIGRTMIN + 3 (e.g. systemd). */
 	if (c->lxc_conf && c->lxc_conf->haltsignal)
 		haltsignal = c->lxc_conf->haltsignal;
-	else if (task_blocking_signal(pid, (SIGRTMIN + 3)))
+	else if (task_blocks_signal(pid, (SIGRTMIN + 3)))
 		haltsignal = (SIGRTMIN + 3);
 
 	/* Add a new state client before sending the shutdown signal so that we

src/lxc/parse.c

@@ -144,29 +144,42 @@ int lxc_file_for_each_line(const char *file, lxc_file_cb callback, void *data)
 int lxc_char_left_gc(const char *buffer, size_t len)
 {
 	size_t i;
+
 	for (i = 0; i < len; i++) {
 		if (buffer[i] == ' ' ||
 		    buffer[i] == '\t')
 			continue;
+
 		return i;
 	}
+
 	return 0;
 }
 
 int lxc_char_right_gc(const char *buffer, size_t len)
 {
 	int i;
+
 	for (i = len - 1; i >= 0; i--) {
 		if (buffer[i] == ' '  ||
 		    buffer[i] == '\t' ||
 		    buffer[i] == '\n' ||
 		    buffer[i] == '\0')
 			continue;
+
 		return i + 1;
 	}
+
 	return 0;
 }
 
+char *lxc_trim_whitespace_in_place(char *buffer)
+{
+	buffer += lxc_char_left_gc(buffer, strlen(buffer));
+	buffer[lxc_char_right_gc(buffer, strlen(buffer))] = '\0';
+	return buffer;
+}
+
 int lxc_is_line_empty(const char *line)
 {
 	int i;

src/lxc/parse.h

@@ -41,6 +41,8 @@ extern int lxc_char_left_gc(const char *buffer, size_t len);
 
 extern int lxc_char_right_gc(const char *buffer, size_t len);
 
+extern char *lxc_trim_whitespace_in_place(char *buffer);
+
 extern int lxc_is_line_empty(const char *line);
 
 /* mmap() wrapper. lxc_strmmap() will take care to \0-terminate files so that

src/lxc/seccomp.c

@@ -215,13 +215,13 @@ static int get_seccomp_arg_value(char *key, struct seccomp_v2_rule_args *rule_ar
 		return -1;
 	}
 
-	ret = lxc_safe_uint64(v, &value);
+	ret = lxc_safe_uint64(v, &value, 0);
 	if (ret < 0) {
 		ERROR("Invalid argument value");
 		return -1;
 	}
 
-	ret = lxc_safe_uint64(m, &mask);
+	ret = lxc_safe_uint64(m, &mask, 0);
 	if (ret < 0) {
 		ERROR("Invalid argument mask");
 		return -1;

src/lxc/utils.c

@@ -1815,12 +1815,12 @@ int lxc_count_file_lines(const char *fn)
 /* Check whether a signal is blocked by a process. */
 /* /proc/pid-to-str/status\0 = (5 + 21 + 7 + 1) */
 #define __PROC_STATUS_LEN (6 + (LXC_NUMSTRLEN64) + 7 + 1)
-bool task_blocking_signal(pid_t pid, int signal)
+bool task_blocks_signal(pid_t pid, int signal)
 {
 	int ret;
 	char status[__PROC_STATUS_LEN];
 	FILE *f;
-	long unsigned int sigblk = 0;
+	uint64_t sigblk = 0, one = 1;
 	size_t n = 0;
 	bool bret = false;
 	char *line = NULL;
@@ -1834,14 +1834,20 @@ bool task_blocking_signal(pid_t pid, int signal)
 		return bret;
 
 	while (getline(&line, &n, f) != -1) {
+		char *numstr;
+
 		if (strncmp(line, "SigBlk:", 7))
 			continue;
 
-		if (sscanf(line + 7, "%lx", &sigblk) != 1)
+		numstr = lxc_trim_whitespace_in_place(line + 7);
+		ret = lxc_safe_uint64(numstr, &sigblk, 16);
+		if (ret < 0)
 			goto out;
+
+		break;
 	}
 
-	if (sigblk & (1LU << (signal - 1)))
+	if (sigblk & (one << (signal - 1)))
 		bret = true;
 
 out:
@@ -1958,7 +1964,7 @@ int lxc_safe_ulong(const char *numstr, unsigned long *converted)
 	return 0;
 }
 
-int lxc_safe_uint64(const char *numstr, uint64_t *converted)
+int lxc_safe_uint64(const char *numstr, uint64_t *converted, int base)
 {
 	char *err = NULL;
 	uint64_t u;
@@ -1970,7 +1976,7 @@ int lxc_safe_uint64(const char *numstr, uint64_t *converted)
 		return -EINVAL;
 
 	errno = 0;
-	u = strtoull(numstr, &err, 0);
+	u = strtoull(numstr, &err, base);
 	if (errno == ERANGE && u == ULLONG_MAX)
 		return -ERANGE;
 

src/lxc/utils.h

@@ -523,7 +523,7 @@ extern int lxc_count_file_lines(const char *fn);
 extern int lxc_preserve_ns(const int pid, const char *ns);
 
 /* Check whether a signal is blocked by a process. */
-extern bool task_blocking_signal(pid_t pid, int signal);
+extern bool task_blocks_signal(pid_t pid, int signal);
 
 /* Helper functions to parse numbers. */
 extern int lxc_safe_uint(const char *numstr, unsigned int *converted);
@@ -531,7 +531,7 @@ extern int lxc_safe_int(const char *numstr, int *converted);
 extern int lxc_safe_long(const char *numstr, long int *converted);
 extern int lxc_safe_long_long(const char *numstr, long long int *converted);
 extern int lxc_safe_ulong(const char *numstr, unsigned long *converted);
-extern int lxc_safe_uint64(const char *numstr, uint64_t *converted);
+extern int lxc_safe_uint64(const char *numstr, uint64_t *converted, int base);
 /* Handles B, kb, MB, GB. Detects overflows and reports -ERANGE. */
 extern int parse_byte_size_string(const char *s, int64_t *converted);
 

src/tests/Makefile.am

@@ -44,7 +44,8 @@ AM_CFLAGS=-DLXCROOTFSMOUNT=\"$(LXCROOTFSMOUNT)\" \
 	-I $(top_srcdir)/src/lxc \
 	-I $(top_srcdir)/src/lxc/bdev \
 	-I $(top_srcdir)/src/lxc/cgroups \
-	-I $(top_srcdir)/src/lxc/tools
+	-I $(top_srcdir)/src/lxc/tools \
+	-pthread
 
 if ENABLE_APPARMOR
 AM_CFLAGS += -DHAVE_APPARMOR

src/tests/lxc-test-utils.c

@@ -27,14 +27,16 @@
 #include <fcntl.h>
 #include <inttypes.h>
 #include <limits.h>
+#include <pthread.h>
 #include <sched.h>
+#include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-#include <unistd.h>
 #include <sys/mount.h>
 #include <sys/stat.h>
 #include <sys/types.h>
+#include <unistd.h>
 
 #include "lxctest.h"
 #include "utils.h"
@@ -507,6 +509,67 @@ void test_lxc_config_net_hwaddr(void)
 		exit(EXIT_FAILURE);
 }
 
+void test_task_blocks_signal(void)
+{
+	int ret;
+	pid_t pid;
+
+	pid = fork();
+	if (pid < 0)
+		_exit(EXIT_FAILURE);
+
+	if (pid == 0) {
+		int i;
+		sigset_t mask;
+		int signals[] = {SIGBUS,   SIGILL,       SIGSEGV,
+				 SIGWINCH, SIGQUIT,      SIGUSR1,
+				 SIGUSR2,  SIGRTMIN + 3, SIGRTMIN + 4};
+
+		sigemptyset(&mask);
+
+		for (i = 0; i < (sizeof(signals) / sizeof(signals[0])); i++) {
+			ret = sigaddset(&mask, signals[i]);
+			if (ret < 0)
+				_exit(EXIT_FAILURE);
+		}
+
+		ret = pthread_sigmask(SIG_BLOCK, &mask, NULL);
+		if (ret < 0) {
+			lxc_error("%s\n", "Failed to block signals");
+			_exit(EXIT_FAILURE);
+		}
+
+		for (i = 0; i < (sizeof(signals) / sizeof(signals[0])); i++) {
+			if (!task_blocks_signal(getpid(), signals[i])) {
+				lxc_error("Failed to detect blocked signal "
+					  "(idx = %d, signal number = %d)\n",
+					  i, signals[i]);
+				_exit(EXIT_FAILURE);
+			}
+		}
+
+		if (task_blocks_signal(getpid(), SIGKILL)) {
+			lxc_error("%s\n",
+				  "Falsely detected SIGKILL as blocked signal");
+			_exit(EXIT_FAILURE);
+		}
+
+		if (task_blocks_signal(getpid(), SIGSTOP)) {
+			lxc_error("%s\n",
+				  "Falsely detected SIGSTOP as blocked signal");
+			_exit(EXIT_FAILURE);
+		}
+
+		_exit(EXIT_SUCCESS);
+	}
+
+	ret = wait_for_pid(pid);
+	if (ret < 0)
+		_exit(EXIT_FAILURE);
+
+	return;
+}
+
 int main(int argc, char *argv[])
 {
 	test_lxc_string_replace();
@@ -518,6 +581,7 @@ int main(int argc, char *argv[])
 	test_lxc_safe_long();
 	test_parse_byte_size_string();
 	test_lxc_config_net_hwaddr();
+	test_task_blocks_signal();
 
 	exit(EXIT_SUCCESS);
 }