tree-wide: use __u32 for capabilities

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

src/lxc/attach.c

@@ -775,10 +775,14 @@ int lxc_attach_remount_sys_proc(void)
 
 static int drop_capabilities(struct attach_context *ctx)
 {
-	int last_cap;
+	int ret;
+	__u32 last_cap;
 
-	last_cap = lxc_caps_last_cap();
-	for (int cap = 0; cap <= last_cap; cap++) {
+	ret = lxc_caps_last_cap(&last_cap);
+	if (ret)
+		return ret;
+
+	for (__u32 cap = 0; cap <= last_cap; cap++) {
 		if (ctx->capability_mask & (1LL << cap))
 			continue;
 

src/lxc/caps.c

@@ -90,7 +90,7 @@ int lxc_ambient_caps_up(void)
 	__do_free char *cap_names = NULL;
 	int ret;
 	cap_value_t cap;
-	int last_cap = CAP_LAST_CAP;
+	cap_value_t last_cap = CAP_LAST_CAP;
 
 	if (!getuid() || geteuid())
 		return 0;
@@ -207,55 +207,62 @@ int lxc_caps_init(void)
 	return 0;
 }
 
-static long int _real_caps_last_cap(void)
+static int __caps_last_cap(__u32 *cap)
 {
 	__do_close int fd = -EBADF;
-	__s32 result = -1;
 
-	/* Try to get the maximum capability over the kernel interface
+	/*
+	 * Try to get the maximum capability over the kernel interface
 	 * introduced in v3.2.
 	 */
-	fd = open("/proc/sys/kernel/cap_last_cap", O_RDONLY | O_CLOEXEC);
+	fd = open_at(-EBADF,
+		     "/proc/sys/kernel/cap_last_cap",
+		     PROTECT_OPEN,
+		     PROTECT_LOOKUP_ABSOLUTE,
+		     0);
 	if (fd >= 0) {
-		ssize_t n;
-		char *ptr;
-		char buf[INTTYPE_TO_STRLEN(int)] = {0};
+		ssize_t ret;
+		unsigned res;
+		char buf[INTTYPE_TO_STRLEN(__u32)] = {0};
 
-		n = lxc_read_nointr(fd, buf, STRARRAYLEN(buf));
-		if (n >= 0) {
-			errno = 0;
-			result = strtol(buf, &ptr, 10);
-			if (!ptr || (*ptr != '\0' && *ptr != '\n') || errno != 0)
-				result = -1;
-		}
+		ret = lxc_read_nointr(fd, buf, STRARRAYLEN(buf));
+		if (ret <= 0)
+			return ret_errno(EINVAL);
 
-		close(fd);
+		ret = lxc_safe_uint(buf, &res);
+		if (ret < 0)
+			return ret;
+
+		*cap = (__u32)res;
 	} else {
-		__s32 cap = 0;
+		__u32 cur_cap = 0;
 
-		/* Try to get it manually by trying to get the status of each
+		/*
+		 * Try to get it manually by trying to get the status of each
 		 * capability individually from the kernel.
 		 */
-		while (prctl(PR_CAPBSET_READ, prctl_arg(cap)) >= 0)
-			cap++;
+		while (prctl(PR_CAPBSET_READ, prctl_arg(cur_cap)) >= 0)
+			cur_cap++;
 
-		result = cap - 1;
+		*cap = cur_cap - 1;
 	}
 
-	return result;
+	return 0;
 }
 
-int lxc_caps_last_cap(void)
+int lxc_caps_last_cap(__u32 *cap)
 {
-	static __s32 last_cap = -1;
+	static int ret = -1;
+	static __u32 last_cap = 0;
 
-	if (last_cap < 0) {
-		last_cap = _real_caps_last_cap();
-		if (last_cap < 0 || last_cap > INT_MAX)
-			last_cap = -1;
+	if (ret < 0) {
+		ret = __caps_last_cap(&last_cap);
+		if (ret)
+			return ret;
 	}
 
-	return last_cap;
+	*cap = last_cap;
+	return 0;
 }
 
 static bool lxc_cap_is_set(cap_t caps, cap_value_t cap, cap_flag_t flag)

src/lxc/caps.h

@@ -18,7 +18,7 @@ __hidden extern int lxc_caps_up(void);
 __hidden extern int lxc_ambient_caps_up(void);
 __hidden extern int lxc_ambient_caps_down(void);
 __hidden extern int lxc_caps_init(void);
-__hidden extern int lxc_caps_last_cap(void);
+__hidden extern int lxc_caps_last_cap(__u32 *cap);
 __hidden extern bool lxc_proc_cap_is_set(cap_value_t cap, cap_flag_t flag);
 __hidden extern bool lxc_file_cap_is_set(const char *path, cap_value_t cap, cap_flag_t flag);
 #else
@@ -47,7 +47,7 @@ static inline int lxc_caps_init(void)
 	return 0;
 }
 
-static inline int lxc_caps_last_cap(void)
+static inline int lxc_caps_last_cap(__u32 *cap)
 {
 	return 0;
 }

src/lxc/conf.c

@@ -133,7 +133,7 @@ struct mount_opt {
 
 struct caps_opt {
 	char *name;
-	int value;
+	__u32 value;
 };
 
 struct limit_opt {
@@ -3097,44 +3097,45 @@ out:
 	return fret;
 }
 
-int parse_cap(const char *cap)
+int parse_cap(const char *cap_name, __u32 *cap)
 {
-	size_t i;
-	int capid = -1;
 	size_t end = sizeof(caps_opt) / sizeof(caps_opt[0]);
-	char *ptr = NULL;
+	int ret;
+	unsigned int res;
+	__u32 last_cap;
 
-	if (strequal(cap, "none"))
+	if (strequal(cap_name, "none"))
 		return -2;
 
-	for (i = 0; i < end; i++) {
-		if (!strequal(cap, caps_opt[i].name))
+	for (size_t i = 0; i < end; i++) {
+		if (!strequal(cap_name, caps_opt[i].name))
 			continue;
 
-		capid = caps_opt[i].value;
-		break;
+		*cap = caps_opt[i].value;
+		return 0;
 	}
 
-	if (capid < 0) {
-		/* Try to see if it's numeric, so the user may specify
-		 * capabilities that the running kernel knows about but we
-		 * don't
-		 */
-		errno = 0;
-		capid = strtol(cap, &ptr, 10);
-		if (!ptr || *ptr != '\0' || errno != 0)
-			/* not a valid number */
-			capid = -1;
-		else if (capid > lxc_caps_last_cap())
-			/* we have a number but it's not a valid
-			 * capability */
-			capid = -1;
-	}
+	/*
+	 * Try to see if it's numeric, so the user may specify
+	 * capabilities that the running kernel knows about but we
+	 * don't.
+	 */
+	ret = lxc_safe_uint(cap_name, &res);
+	if (ret < 0)
+		return -1;
 
-	return capid;
+	ret = lxc_caps_last_cap(&last_cap);
+	if (ret)
+		return -1;
+
+	if ((__u32)res > last_cap)
+		return -1;
+
+	*cap = (__u32)res;
+	return 0;
 }
 
-bool has_cap(int cap, struct lxc_conf *conf)
+bool has_cap(__u32 cap, struct lxc_conf *conf)
 {
 	bool cap_in_list = false;
 	struct cap_entry *cap_entry;
@@ -3176,32 +3177,30 @@ static int capabilities_deny(struct lxc_conf *conf)
 static int capabilities_allow(struct lxc_conf *conf)
 {
 	__do_free __u32 *keep_bits = NULL;
-	__s32 numcaps;
+	int ret;
 	struct cap_entry *cap;
-	size_t nr_u32;
+	__u32 last_cap, nr_u32;
 
-	numcaps = lxc_caps_last_cap();
-	if (numcaps <= 0 || numcaps > 200)
+	ret = lxc_caps_last_cap(&last_cap);
+	if (ret || last_cap > 200)
 		return ret_errno(EINVAL);
 
-	TRACE("Found %d capabilities", numcaps);
+	TRACE("Found %d capabilities", last_cap);
 
-	nr_u32 = BITS_TO_LONGS(numcaps);
+	nr_u32 = BITS_TO_LONGS(last_cap);
 	keep_bits = zalloc(nr_u32 * sizeof(__u32));
 	if (!keep_bits)
 		return ret_errno(ENOMEM);
 
 	list_for_each_entry(cap, &conf->caps.list, head) {
-		if (cap->cap > numcaps)
+		if (cap->cap > last_cap)
 			continue;
 
 		set_bit(cap->cap, keep_bits);
 		DEBUG("Keeping %s (%d) capability", cap->cap_name, cap->cap);
 	}
 
-	for (__s32 cap_bit = 0; cap_bit <= numcaps; cap_bit++) {
-		int ret;
-
+	for (__u32 cap_bit = 0; cap_bit <= last_cap; cap_bit++) {
 		if (is_set(cap_bit, keep_bits))
 			continue;
 
@@ -4267,7 +4266,7 @@ int lxc_sync_fds_child(struct lxc_handler *handler)
 	return 0;
 }
 
-static int setcup_capabilities(struct lxc_conf *conf)
+static int setup_capabilities(struct lxc_conf *conf)
 {
 	int ret;
 
@@ -4423,7 +4422,7 @@ int lxc_setup(struct lxc_handler *handler)
 	if (ret < 0)
 		return log_error(-1, "Failed to setup sysctl parameters");
 
-	ret = setcup_capabilities(lxc_conf);
+	ret = setup_capabilities(lxc_conf);
 	if (ret < 0)
 		return log_error(-1, "Failed to setup capabilities");
 

src/lxc/conf.h

@@ -343,7 +343,7 @@ struct environment_entry {
 
 struct cap_entry {
 	char *cap_name;
-	int cap;
+	__u32 cap;
 	struct list_head head;
 };
 
@@ -579,10 +579,17 @@ __hidden extern int run_script(const char *name, const char *section, const char
 __hidden extern int run_script_argv(const char *name, unsigned int hook_version, const char *section,
 				    const char *script, const char *hookname, char **argsin);
 
-__hidden extern bool has_cap(int cap, struct lxc_conf *conf);
-static inline bool lxc_wants_cap(int cap, struct lxc_conf *conf)
+__hidden extern bool has_cap(__u32 cap, struct lxc_conf *conf);
+static inline bool lxc_wants_cap(__u32 cap, struct lxc_conf *conf)
 {
-	if (lxc_caps_last_cap() < cap)
+	__u32 last_cap;
+	int ret;
+
+	ret = lxc_caps_last_cap(&last_cap);
+	if (ret)
+		return false;
+
+	if (last_cap < cap)
 		return false;
 
 	return has_cap(cap, conf);
@@ -662,6 +669,6 @@ static inline int lxc_personality(personality_t persona)
 }
 
 __hidden extern int lxc_set_environment(const struct lxc_conf *conf);
-__hidden extern int parse_cap(const char *cap);
+__hidden extern int parse_cap(const char *cap_name, __u32 *cap);
 
 #endif /* __LXC_CONF_H */

src/lxc/confile.c

@@ -2390,7 +2390,8 @@ static int add_cap_entry(struct lxc_conf *conf, char *caps, bool keep)
 	 */
 	lxc_iterate_parts(token, caps, " \t") {
 		__do_free struct cap_entry *new_cap = NULL;
-		int cap;
+		int ret;
+		__u32 cap;
 
 		if (strequal(token, "none")) {
 			if (!keep)
@@ -2400,9 +2401,9 @@ static int add_cap_entry(struct lxc_conf *conf, char *caps, bool keep)
 			continue;
 		}
 
-		cap = parse_cap(token);
-		if (cap < 0) {
-			if (cap != -2)
+		ret = parse_cap(token, &cap);
+		if (ret < 0) {
+			if (ret != -2)
 				return syserror_set(-EINVAL, "Invalid capability specified");
 
 			INFO("Ignoring unknown capability \"%s\"", token);

src/tests/capabilities_allow.c

@@ -40,10 +40,16 @@
 #if HAVE_LIBCAP
 static int capabilities_allow(void *payload)
 {
-	int last_cap;
+	int ret;
+	__u32 last_cap;
 
-	last_cap = lxc_caps_last_cap();
-	for (int cap = 0; cap <= last_cap; cap++) {
+	ret = lxc_caps_last_cap(&last_cap);
+	if (ret) {
+		lxc_error("%s\n", "Failed to retrieve last capability");
+		return EXIT_FAILURE;
+	}
+
+	for (__u32 cap = 0; cap <= last_cap; cap++) {
 		bool bret;
 
 		if (cap == CAP_MKNOD)