From d2f2714398d415eb9a628aab82b332b92ad5c923 Mon Sep 17 00:00:00 2001
From: Kimplul <kimi.h.kuparinen@gmail.com>
Date: Tue, 20 Sep 2022 15:38:06 +0300
Subject: add capability subsystem and syscalls

---
 common/uapi/cap.c      | 87 ++++++++++++++++++++++++++++++++++++++++++++++++++
 common/uapi/dispatch.c |  5 +++
 2 files changed, 92 insertions(+)
 create mode 100644 common/uapi/cap.c

(limited to 'common/uapi')

diff --git a/common/uapi/cap.c b/common/uapi/cap.c
new file mode 100644
index 0000000..84dbc45
--- /dev/null
+++ b/common/uapi/cap.c
@@ -0,0 +1,87 @@
+#include <apos/uapi.h>
+#include <apos/caps.h>
+#include <apos/tcb.h>
+
+/**
+ * @file cap.c
+ * Sycalls handlers for thread capabilities.
+ */
+
+/**
+ * Check that values are legal for thread ID and offset.
+ *
+ * @param tid Thread ID of thread whose caps should be fetched.
+ * @param off Offset of capabilities.
+ * @return Pointer to capabilities of \p tid, \c 0 otherwise.
+ */
+static capflags_t *__get_tcb_caps(id_t tid, size_t off)
+{
+	if (!cap_off_ok(off))
+		return NULL;
+
+	struct tcb *t = get_tcb(tid);
+	if (!t)
+		return NULL;
+
+	return &t->caps;
+}
+
+/**
+ * Set capabilities.
+ *
+ * @param tid Thread ID whose capabilities to set.
+ * @param off Offset of capability, multiple of \c bits(cap).
+ * @param caps Mask of capabilities to set.
+ * @return \ref OK on success, \ref ERR_INVAL on invalid input.
+ */
+SYSCALL_DEFINE3(set_cap)(sys_arg_t tid, sys_arg_t off, sys_arg_t caps)
+{
+	struct tcb *t = cur_tcb();
+	if (!is_set(t->caps, CAP_CAPS))
+		return (struct sys_ret){ERR_PERM, 0, 0, 0, 0, 0};
+
+	capflags_t *c;
+	if (!(c = __get_tcb_caps(tid, off)))
+		return (struct sys_ret){ERR_INVAL, 0, 0, 0, 0, 0};
+
+	set_caps(*c, off, caps);
+	return (struct sys_ret){OK, 0, 0, 0, 0, 0};
+}
+
+/**
+ * Get capabilities.
+ *
+ * @param tid Thread ID whose capabilities to get.
+ * @param off Offset of capability, multiple of \c bits(cap).
+ * @return \ref OK, capabilities.
+ */
+SYSCALL_DEFINE2(get_cap)(sys_arg_t tid, sys_arg_t off)
+{
+	capflags_t *c;
+	if (!(c = __get_tcb_caps(tid, off)))
+		return (struct sys_ret){ERR_INVAL, 0, 0, 0, 0, 0};
+
+	return (struct sys_ret){OK, get_caps(*c, off), 0, 0, 0, 0};
+}
+
+/**
+ * Clear capabilities.
+ *
+ * @param tid Thread ID whose capabilities to clear.
+ * @param off Offset of capability, multiple of \c bits(cap).
+ * @param caps Mask of capabilities to clear.
+ * @return \ref OK.
+ */
+SYSCALL_DEFINE3(clear_cap)(sys_arg_t tid, sys_arg_t off, sys_arg_t caps)
+{
+	struct tcb *t = cur_tcb();
+	if (!is_set(t->caps, CAP_CAPS))
+		return (struct sys_ret){ERR_PERM, 0, 0, 0, 0, 0};
+
+	capflags_t *c;
+	if (!(c = __get_tcb_caps(tid, off)))
+		return (struct sys_ret){ERR_INVAL, 0, 0, 0, 0, 0};
+
+	clear_caps(*c, off, caps);
+	return (struct sys_ret){OK, 0, 0, 0, 0, 0};
+}
diff --git a/common/uapi/dispatch.c b/common/uapi/dispatch.c
index f0f6ae0..30b2e2e 100644
--- a/common/uapi/dispatch.c
+++ b/common/uapi/dispatch.c
@@ -46,6 +46,11 @@ static const sys_t syscall_table[] = {
 	/* conf */
 	[SYS_CONF_SET] = sys_conf_set,
 	[SYS_CONF_GET] = sys_conf_get,
+
+	[SYS_SET_CAP] = sys_set_cap,
+	[SYS_GET_CAP] = sys_get_cap,
+	[SYS_CLEAR_CAP] = sys_clear_cap,
+
 	[SYS_POWEROFF] = sys_poweroff,
 };
 
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