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-rw-r--r--arch/um/Kconfig.common1
-rw-r--r--arch/um/Kconfig.um16
-rw-r--r--arch/um/drivers/ubd_kern.c27
-rw-r--r--arch/um/include/asm/hardirq.h23
-rw-r--r--arch/um/include/asm/syscall-generic.h138
-rw-r--r--arch/um/include/asm/thread_info.h2
-rw-r--r--arch/um/include/shared/os.h3
-rw-r--r--arch/um/kernel/skas/syscall.c31
-rw-r--r--arch/um/os-Linux/file.c19
-rw-r--r--arch/um/os-Linux/mem.c17
-rw-r--r--arch/um/os-Linux/signal.c16
-rw-r--r--arch/um/os-Linux/skas/process.c7
-rw-r--r--arch/um/os-Linux/start_up.c2
13 files changed, 253 insertions, 49 deletions
diff --git a/arch/um/Kconfig.common b/arch/um/Kconfig.common
index d195a87ca542..cc0013475444 100644
--- a/arch/um/Kconfig.common
+++ b/arch/um/Kconfig.common
@@ -2,6 +2,7 @@ config UML
bool
default y
select HAVE_ARCH_AUDITSYSCALL
+ select HAVE_ARCH_SECCOMP_FILTER
select HAVE_UID16
select HAVE_FUTEX_CMPXCHG if FUTEX
select GENERIC_IRQ_SHOW
diff --git a/arch/um/Kconfig.um b/arch/um/Kconfig.um
index 28a9885e3a37..4b2ed5858b2e 100644
--- a/arch/um/Kconfig.um
+++ b/arch/um/Kconfig.um
@@ -104,3 +104,19 @@ config PGTABLE_LEVELS
int
default 3 if 3_LEVEL_PGTABLES
default 2
+
+config SECCOMP
+ def_bool y
+ prompt "Enable seccomp to safely compute untrusted bytecode"
+ ---help---
+ This kernel feature is useful for number crunching applications
+ that may need to compute untrusted bytecode during their
+ execution. By using pipes or other transports made available to
+ the process as file descriptors supporting the read/write
+ syscalls, it's possible to isolate those applications in
+ their own address space using seccomp. Once seccomp is
+ enabled via prctl(PR_SET_SECCOMP), it cannot be disabled
+ and the task is only allowed to execute a few safe syscalls
+ defined by each seccomp mode.
+
+ If unsure, say Y.
diff --git a/arch/um/drivers/ubd_kern.c b/arch/um/drivers/ubd_kern.c
index e8ab93c3e638..39ba20755e03 100644
--- a/arch/um/drivers/ubd_kern.c
+++ b/arch/um/drivers/ubd_kern.c
@@ -535,11 +535,7 @@ static int read_cow_bitmap(int fd, void *buf, int offset, int len)
{
int err;
- err = os_seek_file(fd, offset);
- if (err < 0)
- return err;
-
- err = os_read_file(fd, buf, len);
+ err = os_pread_file(fd, buf, len, offset);
if (err < 0)
return err;
@@ -1377,14 +1373,8 @@ static int update_bitmap(struct io_thread_req *req)
if(req->cow_offset == -1)
return 0;
- n = os_seek_file(req->fds[1], req->cow_offset);
- if(n < 0){
- printk("do_io - bitmap lseek failed : err = %d\n", -n);
- return 1;
- }
-
- n = os_write_file(req->fds[1], &req->bitmap_words,
- sizeof(req->bitmap_words));
+ n = os_pwrite_file(req->fds[1], &req->bitmap_words,
+ sizeof(req->bitmap_words), req->cow_offset);
if(n != sizeof(req->bitmap_words)){
printk("do_io - bitmap update failed, err = %d fd = %d\n", -n,
req->fds[1]);
@@ -1399,7 +1389,6 @@ static void do_io(struct io_thread_req *req)
char *buf;
unsigned long len;
int n, nsectors, start, end, bit;
- int err;
__u64 off;
if (req->op == UBD_FLUSH) {
@@ -1428,18 +1417,12 @@ static void do_io(struct io_thread_req *req)
len = (end - start) * req->sectorsize;
buf = &req->buffer[start * req->sectorsize];
- err = os_seek_file(req->fds[bit], off);
- if(err < 0){
- printk("do_io - lseek failed : err = %d\n", -err);
- req->error = 1;
- return;
- }
if(req->op == UBD_READ){
n = 0;
do {
buf = &buf[n];
len -= n;
- n = os_read_file(req->fds[bit], buf, len);
+ n = os_pread_file(req->fds[bit], buf, len, off);
if (n < 0) {
printk("do_io - read failed, err = %d "
"fd = %d\n", -n, req->fds[bit]);
@@ -1449,7 +1432,7 @@ static void do_io(struct io_thread_req *req)
} while((n < len) && (n != 0));
if (n < len) memset(&buf[n], 0, len - n);
} else {
- n = os_write_file(req->fds[bit], buf, len);
+ n = os_pwrite_file(req->fds[bit], buf, len, off);
if(n != len){
printk("do_io - write failed err = %d "
"fd = %d\n", -n, req->fds[bit]);
diff --git a/arch/um/include/asm/hardirq.h b/arch/um/include/asm/hardirq.h
new file mode 100644
index 000000000000..756f0778e327
--- /dev/null
+++ b/arch/um/include/asm/hardirq.h
@@ -0,0 +1,23 @@
+#ifndef __ASM_UM_HARDIRQ_H
+#define __ASM_UM_HARDIRQ_H
+
+#include <linux/cache.h>
+#include <linux/threads.h>
+
+typedef struct {
+ unsigned int __softirq_pending;
+} ____cacheline_aligned irq_cpustat_t;
+
+#include <linux/irq_cpustat.h> /* Standard mappings for irq_cpustat_t above */
+#include <linux/irq.h>
+
+#ifndef ack_bad_irq
+static inline void ack_bad_irq(unsigned int irq)
+{
+ printk(KERN_CRIT "unexpected IRQ trap at vector %02x\n", irq);
+}
+#endif
+
+#define __ARCH_IRQ_EXIT_IRQS_DISABLED 1
+
+#endif /* __ASM_UM_HARDIRQ_H */
diff --git a/arch/um/include/asm/syscall-generic.h b/arch/um/include/asm/syscall-generic.h
new file mode 100644
index 000000000000..9fb9cf8cd39a
--- /dev/null
+++ b/arch/um/include/asm/syscall-generic.h
@@ -0,0 +1,138 @@
+/*
+ * Access to user system call parameters and results
+ *
+ * See asm-generic/syscall.h for function descriptions.
+ *
+ * Copyright (C) 2015 Mickaël Salaün <mic@digikod.net>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef __UM_SYSCALL_GENERIC_H
+#define __UM_SYSCALL_GENERIC_H
+
+#include <asm/ptrace.h>
+#include <linux/err.h>
+#include <linux/sched.h>
+#include <sysdep/ptrace.h>
+
+static inline int syscall_get_nr(struct task_struct *task, struct pt_regs *regs)
+{
+
+ return PT_REGS_SYSCALL_NR(regs);
+}
+
+static inline void syscall_rollback(struct task_struct *task,
+ struct pt_regs *regs)
+{
+ /* do nothing */
+}
+
+static inline long syscall_get_error(struct task_struct *task,
+ struct pt_regs *regs)
+{
+ const long error = regs_return_value(regs);
+
+ return IS_ERR_VALUE(error) ? error : 0;
+}
+
+static inline long syscall_get_return_value(struct task_struct *task,
+ struct pt_regs *regs)
+{
+ return regs_return_value(regs);
+}
+
+static inline void syscall_set_return_value(struct task_struct *task,
+ struct pt_regs *regs,
+ int error, long val)
+{
+ PT_REGS_SET_SYSCALL_RETURN(regs, (long) error ?: val);
+}
+
+static inline void syscall_get_arguments(struct task_struct *task,
+ struct pt_regs *regs,
+ unsigned int i, unsigned int n,
+ unsigned long *args)
+{
+ const struct uml_pt_regs *r = &regs->regs;
+
+ switch (i) {
+ case 0:
+ if (!n--)
+ break;
+ *args++ = UPT_SYSCALL_ARG1(r);
+ case 1:
+ if (!n--)
+ break;
+ *args++ = UPT_SYSCALL_ARG2(r);
+ case 2:
+ if (!n--)
+ break;
+ *args++ = UPT_SYSCALL_ARG3(r);
+ case 3:
+ if (!n--)
+ break;
+ *args++ = UPT_SYSCALL_ARG4(r);
+ case 4:
+ if (!n--)
+ break;
+ *args++ = UPT_SYSCALL_ARG5(r);
+ case 5:
+ if (!n--)
+ break;
+ *args++ = UPT_SYSCALL_ARG6(r);
+ case 6:
+ if (!n--)
+ break;
+ default:
+ BUG();
+ break;
+ }
+}
+
+static inline void syscall_set_arguments(struct task_struct *task,
+ struct pt_regs *regs,
+ unsigned int i, unsigned int n,
+ const unsigned long *args)
+{
+ struct uml_pt_regs *r = &regs->regs;
+
+ switch (i) {
+ case 0:
+ if (!n--)
+ break;
+ UPT_SYSCALL_ARG1(r) = *args++;
+ case 1:
+ if (!n--)
+ break;
+ UPT_SYSCALL_ARG2(r) = *args++;
+ case 2:
+ if (!n--)
+ break;
+ UPT_SYSCALL_ARG3(r) = *args++;
+ case 3:
+ if (!n--)
+ break;
+ UPT_SYSCALL_ARG4(r) = *args++;
+ case 4:
+ if (!n--)
+ break;
+ UPT_SYSCALL_ARG5(r) = *args++;
+ case 5:
+ if (!n--)
+ break;
+ UPT_SYSCALL_ARG6(r) = *args++;
+ case 6:
+ if (!n--)
+ break;
+ default:
+ BUG();
+ break;
+ }
+}
+
+/* See arch/x86/um/asm/syscall.h for syscall_get_arch() definition. */
+
+#endif /* __UM_SYSCALL_GENERIC_H */
diff --git a/arch/um/include/asm/thread_info.h b/arch/um/include/asm/thread_info.h
index 53968aaf76f9..053baff03674 100644
--- a/arch/um/include/asm/thread_info.h
+++ b/arch/um/include/asm/thread_info.h
@@ -62,11 +62,13 @@ static inline struct thread_info *current_thread_info(void)
#define TIF_SYSCALL_AUDIT 6
#define TIF_RESTORE_SIGMASK 7
#define TIF_NOTIFY_RESUME 8
+#define TIF_SECCOMP 9 /* secure computing */
#define _TIF_SYSCALL_TRACE (1 << TIF_SYSCALL_TRACE)
#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
#define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
#define _TIF_MEMDIE (1 << TIF_MEMDIE)
#define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT)
+#define _TIF_SECCOMP (1 << TIF_SECCOMP)
#endif
diff --git a/arch/um/include/shared/os.h b/arch/um/include/shared/os.h
index 868e6c3f83dd..de5d572225f3 100644
--- a/arch/um/include/shared/os.h
+++ b/arch/um/include/shared/os.h
@@ -146,6 +146,8 @@ extern int os_read_file(int fd, void *buf, int len);
extern int os_write_file(int fd, const void *buf, int count);
extern int os_sync_file(int fd);
extern int os_file_size(const char *file, unsigned long long *size_out);
+extern int os_pread_file(int fd, void *buf, int len, unsigned long long offset);
+extern int os_pwrite_file(int fd, const void *buf, int count, unsigned long long offset);
extern int os_file_modtime(const char *file, unsigned long *modtime);
extern int os_pipe(int *fd, int stream, int close_on_exec);
extern int os_set_fd_async(int fd);
@@ -282,7 +284,6 @@ extern void initial_thread_cb_skas(void (*proc)(void *),
void *arg);
extern void halt_skas(void);
extern void reboot_skas(void);
-extern int get_syscall(struct uml_pt_regs *regs);
/* irq.c */
extern int os_waiting_for_events(struct irq_fd *active_fds);
diff --git a/arch/um/kernel/skas/syscall.c b/arch/um/kernel/skas/syscall.c
index 1683b8efdfda..48b0dcbd87be 100644
--- a/arch/um/kernel/skas/syscall.c
+++ b/arch/um/kernel/skas/syscall.c
@@ -5,31 +5,38 @@
#include <linux/kernel.h>
#include <linux/ptrace.h>
+#include <linux/seccomp.h>
#include <kern_util.h>
#include <sysdep/ptrace.h>
+#include <sysdep/ptrace_user.h>
#include <sysdep/syscalls.h>
-#include <os.h>
void handle_syscall(struct uml_pt_regs *r)
{
struct pt_regs *regs = container_of(r, struct pt_regs, regs);
- long result;
int syscall;
- if (syscall_trace_enter(regs)) {
- result = -ENOSYS;
+ /* Initialize the syscall number and default return value. */
+ UPT_SYSCALL_NR(r) = PT_SYSCALL_NR(r->gp);
+ PT_REGS_SET_SYSCALL_RETURN(regs, -ENOSYS);
+
+ /* Do the secure computing check first; failures should be fast. */
+ if (secure_computing() == -1)
+ return;
+
+ if (syscall_trace_enter(regs))
goto out;
- }
- syscall = get_syscall(r);
+ /* Update the syscall number after orig_ax has potentially been updated
+ * with ptrace.
+ */
+ UPT_SYSCALL_NR(r) = PT_SYSCALL_NR(r->gp);
+ syscall = UPT_SYSCALL_NR(r);
- if ((syscall > __NR_syscall_max) || syscall < 0)
- result = -ENOSYS;
- else
- result = EXECUTE_SYSCALL(syscall, regs);
+ if (syscall >= 0 && syscall <= __NR_syscall_max)
+ PT_REGS_SET_SYSCALL_RETURN(regs,
+ EXECUTE_SYSCALL(syscall, regs));
out:
- PT_REGS_SET_SYSCALL_RETURN(regs, result);
-
syscall_trace_leave(regs);
}
diff --git a/arch/um/os-Linux/file.c b/arch/um/os-Linux/file.c
index 26e0164895e4..2db18cbbb0ea 100644
--- a/arch/um/os-Linux/file.c
+++ b/arch/um/os-Linux/file.c
@@ -264,6 +264,15 @@ int os_read_file(int fd, void *buf, int len)
return n;
}
+int os_pread_file(int fd, void *buf, int len, unsigned long long offset)
+{
+ int n = pread(fd, buf, len, offset);
+
+ if (n < 0)
+ return -errno;
+ return n;
+}
+
int os_write_file(int fd, const void *buf, int len)
{
int n = write(fd, (void *) buf, len);
@@ -282,6 +291,16 @@ int os_sync_file(int fd)
return n;
}
+int os_pwrite_file(int fd, const void *buf, int len, unsigned long long offset)
+{
+ int n = pwrite(fd, (void *) buf, len, offset);
+
+ if (n < 0)
+ return -errno;
+ return n;
+}
+
+
int os_file_size(const char *file, unsigned long long *size_out)
{
struct uml_stat buf;
diff --git a/arch/um/os-Linux/mem.c b/arch/um/os-Linux/mem.c
index 897e9ad0c108..8b1767668515 100644
--- a/arch/um/os-Linux/mem.c
+++ b/arch/um/os-Linux/mem.c
@@ -106,6 +106,17 @@ static int __init make_tempfile(const char *template)
}
}
+#ifdef O_TMPFILE
+ fd = open(tempdir, O_CLOEXEC | O_RDWR | O_EXCL | O_TMPFILE, 0700);
+ /*
+ * If the running system does not support O_TMPFILE flag then retry
+ * without it.
+ */
+ if (fd != -1 || (errno != EINVAL && errno != EISDIR &&
+ errno != EOPNOTSUPP))
+ return fd;
+#endif
+
tempname = malloc(strlen(tempdir) + strlen(template) + 1);
if (tempname == NULL)
return -1;
@@ -142,12 +153,6 @@ static int __init create_tmp_file(unsigned long long len)
if (fd < 0)
exit(1);
- err = fchmod(fd, 0777);
- if (err < 0) {
- perror("fchmod");
- exit(1);
- }
-
/*
* Seek to len - 1 because writing a character there will
* increase the file size by one byte, to the desired length.
diff --git a/arch/um/os-Linux/signal.c b/arch/um/os-Linux/signal.c
index c211153ca69a..7801666514ed 100644
--- a/arch/um/os-Linux/signal.c
+++ b/arch/um/os-Linux/signal.c
@@ -62,6 +62,7 @@ static void sig_handler_common(int sig, struct siginfo *si, mcontext_t *mc)
static int signals_enabled;
static unsigned int signals_pending;
+static unsigned int signals_active = 0;
void sig_handler(int sig, struct siginfo *si, mcontext_t *mc)
{
@@ -101,7 +102,12 @@ void timer_alarm_handler(int sig, struct siginfo *unused_si, mcontext_t *mc)
block_signals();
+ signals_active |= SIGALRM_MASK;
+
timer_real_alarm_handler(mc);
+
+ signals_active &= ~SIGALRM_MASK;
+
set_signals(enabled);
}
@@ -286,8 +292,16 @@ void unblock_signals(void)
if (save_pending & SIGIO_MASK)
sig_handler_common(SIGIO, NULL, NULL);
- if (save_pending & SIGALRM_MASK)
+ /* Do not reenter the handler */
+
+ if ((save_pending & SIGALRM_MASK) && (!(signals_active & SIGALRM_MASK)))
timer_real_alarm_handler(NULL);
+
+ /* Rerun the loop only if there is still pending SIGIO and not in TIMER handler */
+
+ if (!(signals_pending & SIGIO_MASK) && (signals_active & SIGALRM_MASK))
+ return;
+
}
}
diff --git a/arch/um/os-Linux/skas/process.c b/arch/um/os-Linux/skas/process.c
index b856c66ebd3a..23025d645160 100644
--- a/arch/um/os-Linux/skas/process.c
+++ b/arch/um/os-Linux/skas/process.c
@@ -172,13 +172,6 @@ static void handle_trap(int pid, struct uml_pt_regs *regs,
handle_syscall(regs);
}
-int get_syscall(struct uml_pt_regs *regs)
-{
- UPT_SYSCALL_NR(regs) = PT_SYSCALL_NR(regs->gp);
-
- return UPT_SYSCALL_NR(regs);
-}
-
extern char __syscall_stub_start[];
static int userspace_tramp(void *stack)
diff --git a/arch/um/os-Linux/start_up.c b/arch/um/os-Linux/start_up.c
index 47f1ff056a54..22a358ef1b0c 100644
--- a/arch/um/os-Linux/start_up.c
+++ b/arch/um/os-Linux/start_up.c
@@ -94,6 +94,8 @@ static int start_ptraced_child(void)
{
int pid, n, status;
+ fflush(stdout);
+
pid = fork();
if (pid == 0)
ptrace_child();
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.