#include <linux/slab.h>
#include <linux/syscalls.h>
-/* #define SECCOMP_DEBUG 1 */
+#ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER
+#include <asm/syscall.h>
+#endif
#ifdef CONFIG_SECCOMP_FILTER
-#include <asm/syscall.h>
#include <linux/filter.h>
#include <linux/pid.h>
#include <linux/ptrace.h>
*
* Returns valid seccomp BPF response codes.
*/
-static u32 seccomp_run_filters(int syscall)
+static u32 seccomp_run_filters(struct seccomp_data *sd)
{
struct seccomp_filter *f = ACCESS_ONCE(current->seccomp.filter);
- struct seccomp_data sd;
+ struct seccomp_data sd_local;
u32 ret = SECCOMP_RET_ALLOW;
/* Ensure unexpected behavior doesn't result in failing open. */
/* Make sure cross-thread synced filter points somewhere sane. */
smp_read_barrier_depends();
- populate_seccomp_data(&sd);
+ if (!sd) {
+ populate_seccomp_data(&sd_local);
+ sd = &sd_local;
+ }
/*
* All filters in the list are evaluated and the lowest BPF return
* value always takes priority (ignoring the DATA).
*/
for (; f; f = f->prev) {
- u32 cur_ret = BPF_PROG_RUN(f->prog, (void *)&sd);
+ u32 cur_ret = BPF_PROG_RUN(f->prog, (void *)sd);
if ((cur_ret & SECCOMP_RET_ACTION) < (ret & SECCOMP_RET_ACTION))
ret = cur_ret;
};
#endif
-int __secure_computing(int this_syscall)
+static void __secure_computing_strict(int this_syscall)
+{
+ int *syscall_whitelist = mode1_syscalls;
+#ifdef CONFIG_COMPAT
+ if (is_compat_task())
+ syscall_whitelist = mode1_syscalls_32;
+#endif
+ do {
+ if (*syscall_whitelist == this_syscall)
+ return;
+ } while (*++syscall_whitelist);
+
+#ifdef SECCOMP_DEBUG
+ dump_stack();
+#endif
+ audit_seccomp(this_syscall, SIGKILL, SECCOMP_RET_KILL);
+ do_exit(SIGKILL);
+}
+
+#ifndef CONFIG_HAVE_ARCH_SECCOMP_FILTER
+void secure_computing_strict(int this_syscall)
+{
+ int mode = current->seccomp.mode;
+
+ if (mode == 0)
+ return;
+ else if (mode == SECCOMP_MODE_STRICT)
+ __secure_computing_strict(this_syscall);
+ else
+ BUG();
+}
+#else
+int __secure_computing(void)
{
- int exit_sig = 0;
- int *syscall;
- u32 ret;
+ u32 phase1_result = seccomp_phase1(NULL);
+
+ if (likely(phase1_result == SECCOMP_PHASE1_OK))
+ return 0;
+ else if (likely(phase1_result == SECCOMP_PHASE1_SKIP))
+ return -1;
+ else
+ return seccomp_phase2(phase1_result);
+}
+
+#ifdef CONFIG_SECCOMP_FILTER
+static u32 __seccomp_phase1_filter(int this_syscall, struct seccomp_data *sd)
+{
+ u32 filter_ret, action;
+ int data;
/*
* Make sure that any changes to mode from another thread have
*/
rmb();
- switch (current->seccomp.mode) {
- case SECCOMP_MODE_STRICT:
- syscall = mode1_syscalls;
-#ifdef CONFIG_COMPAT
- if (is_compat_task())
- syscall = mode1_syscalls_32;
+ filter_ret = seccomp_run_filters(sd);
+ data = filter_ret & SECCOMP_RET_DATA;
+ action = filter_ret & SECCOMP_RET_ACTION;
+
+ switch (action) {
+ case SECCOMP_RET_ERRNO:
+ /* Set the low-order 16-bits as a errno. */
+ syscall_set_return_value(current, task_pt_regs(current),
+ -data, 0);
+ goto skip;
+
+ case SECCOMP_RET_TRAP:
+ /* Show the handler the original registers. */
+ syscall_rollback(current, task_pt_regs(current));
+ /* Let the filter pass back 16 bits of data. */
+ seccomp_send_sigsys(this_syscall, data);
+ goto skip;
+
+ case SECCOMP_RET_TRACE:
+ return filter_ret; /* Save the rest for phase 2. */
+
+ case SECCOMP_RET_ALLOW:
+ return SECCOMP_PHASE1_OK;
+
+ case SECCOMP_RET_KILL:
+ default:
+ audit_seccomp(this_syscall, SIGSYS, action);
+ do_exit(SIGSYS);
+ }
+
+ unreachable();
+
+skip:
+ audit_seccomp(this_syscall, 0, action);
+ return SECCOMP_PHASE1_SKIP;
+}
#endif
- do {
- if (*syscall == this_syscall)
- return 0;
- } while (*++syscall);
- exit_sig = SIGKILL;
- ret = SECCOMP_RET_KILL;
- break;
+
+/**
+ * seccomp_phase1() - run fast path seccomp checks on the current syscall
+ * @arg sd: The seccomp_data or NULL
+ *
+ * This only reads pt_regs via the syscall_xyz helpers. The only change
+ * it will make to pt_regs is via syscall_set_return_value, and it will
+ * only do that if it returns SECCOMP_PHASE1_SKIP.
+ *
+ * If sd is provided, it will not read pt_regs at all.
+ *
+ * It may also call do_exit or force a signal; these actions must be
+ * safe.
+ *
+ * If it returns SECCOMP_PHASE1_OK, the syscall passes checks and should
+ * be processed normally.
+ *
+ * If it returns SECCOMP_PHASE1_SKIP, then the syscall should not be
+ * invoked. In this case, seccomp_phase1 will have set the return value
+ * using syscall_set_return_value.
+ *
+ * If it returns anything else, then the return value should be passed
+ * to seccomp_phase2 from a context in which ptrace hooks are safe.
+ */
+u32 seccomp_phase1(struct seccomp_data *sd)
+{
+ int mode = current->seccomp.mode;
+ int this_syscall = sd ? sd->nr :
+ syscall_get_nr(current, task_pt_regs(current));
+
+ switch (mode) {
+ case SECCOMP_MODE_STRICT:
+ __secure_computing_strict(this_syscall); /* may call do_exit */
+ return SECCOMP_PHASE1_OK;
#ifdef CONFIG_SECCOMP_FILTER
- case SECCOMP_MODE_FILTER: {
- int data;
- struct pt_regs *regs = task_pt_regs(current);
- ret = seccomp_run_filters(this_syscall);
- data = ret & SECCOMP_RET_DATA;
- ret &= SECCOMP_RET_ACTION;
- switch (ret) {
- case SECCOMP_RET_ERRNO:
- /* Set the low-order 16-bits as a errno. */
- syscall_set_return_value(current, regs,
- -data, 0);
- goto skip;
- case SECCOMP_RET_TRAP:
- /* Show the handler the original registers. */
- syscall_rollback(current, regs);
- /* Let the filter pass back 16 bits of data. */
- seccomp_send_sigsys(this_syscall, data);
- goto skip;
- case SECCOMP_RET_TRACE:
- /* Skip these calls if there is no tracer. */
- if (!ptrace_event_enabled(current, PTRACE_EVENT_SECCOMP)) {
- syscall_set_return_value(current, regs,
- -ENOSYS, 0);
- goto skip;
- }
- /* Allow the BPF to provide the event message */
- ptrace_event(PTRACE_EVENT_SECCOMP, data);
- /*
- * The delivery of a fatal signal during event
- * notification may silently skip tracer notification.
- * Terminating the task now avoids executing a system
- * call that may not be intended.
- */
- if (fatal_signal_pending(current))
- break;
- if (syscall_get_nr(current, regs) < 0)
- goto skip; /* Explicit request to skip. */
-
- return 0;
- case SECCOMP_RET_ALLOW:
- return 0;
- case SECCOMP_RET_KILL:
- default:
- break;
- }
- exit_sig = SIGSYS;
- break;
- }
+ case SECCOMP_MODE_FILTER:
+ return __seccomp_phase1_filter(this_syscall, sd);
#endif
default:
BUG();
}
+}
-#ifdef SECCOMP_DEBUG
- dump_stack();
-#endif
- audit_seccomp(this_syscall, exit_sig, ret);
- do_exit(exit_sig);
-#ifdef CONFIG_SECCOMP_FILTER
-skip:
- audit_seccomp(this_syscall, exit_sig, ret);
-#endif
- return -1;
+/**
+ * seccomp_phase2() - finish slow path seccomp work for the current syscall
+ * @phase1_result: The return value from seccomp_phase1()
+ *
+ * This must be called from a context in which ptrace hooks can be used.
+ *
+ * Returns 0 if the syscall should be processed or -1 to skip the syscall.
+ */
+int seccomp_phase2(u32 phase1_result)
+{
+ struct pt_regs *regs = task_pt_regs(current);
+ u32 action = phase1_result & SECCOMP_RET_ACTION;
+ int data = phase1_result & SECCOMP_RET_DATA;
+
+ BUG_ON(action != SECCOMP_RET_TRACE);
+
+ audit_seccomp(syscall_get_nr(current, regs), 0, action);
+
+ /* Skip these calls if there is no tracer. */
+ if (!ptrace_event_enabled(current, PTRACE_EVENT_SECCOMP)) {
+ syscall_set_return_value(current, regs,
+ -ENOSYS, 0);
+ return -1;
+ }
+
+ /* Allow the BPF to provide the event message */
+ ptrace_event(PTRACE_EVENT_SECCOMP, data);
+ /*
+ * The delivery of a fatal signal during event
+ * notification may silently skip tracer notification.
+ * Terminating the task now avoids executing a system
+ * call that may not be intended.
+ */
+ if (fatal_signal_pending(current))
+ do_exit(SIGSYS);
+ if (syscall_get_nr(current, regs) < 0)
+ return -1; /* Explicit request to skip. */
+
+ return 0;
}
+#endif /* CONFIG_HAVE_ARCH_SECCOMP_FILTER */
long prctl_get_seccomp(void)
{
git.samba.org / sfrench / cifs-2.6.git / blobdiff