Merge tag 'uml-for-linux-6.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux

Pull UML updates from Johannes Berg:
 "The only really new thing is the long-standing seccomp work
  (originally from 2021!). Wven if it still isn't enabled by default due
  to security concerns it can still be used e.g. for tests.

   - remove obsolete network transports

   - remove PCI IO port support

   - start adding seccomp-based process handling instead of ptrace"

* tag 'uml-for-linux-6.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux: (29 commits)
  um: remove "extern" from implementation of sigchld_handler
  um: fix unused variable warning
  um: fix SECCOMP 32bit xstate register restore
  um: pass FD for memory operations when needed
  um: Add SECCOMP support detection and initialization
  um: Implement kernel side of SECCOMP based process handling
  um: Track userspace children dying in SECCOMP mode
  um: Add helper functions to get/set state for SECCOMP
  um: Add stub side of SECCOMP/futex based process handling
  um: Move faultinfo extraction into userspace routine
  um: vector: Use mac_pton() for MAC address parsing
  um: vector: Clean up and modernize log messages
  um: chan_kern: use raw spinlock for irqs_to_free_lock
  MAINTAINERS: remove obsolete file entry in TUN/TAP DRIVER
  um: Fix tgkill compile error on old host OSes
  um: stop using PCI port I/O
  um: Remove legacy network transport infrastructure
  um: vector: Eliminate the dependency on uml_net
  um: Remove obsolete legacy network transports
  um/asm: Replace "REP; NOP" with PAUSE mnemonic
  ...

6 files changed, 66 insertions, 0 deletions

diff --git a/arch/x86/um/shared/sysdep/kernel-offsets.h b/arch/x86/um/shared/sysdep/kernel-offsets.h
index 48de3a71f845f..6fd1ed4003992 100644
--- a/arch/x86/um/shared/sysdep/kernel-offsets.h
+++ b/arch/x86/um/shared/sysdep/kernel-offsets.h
@@ -4,7 +4,9 @@
 #include <linux/elf.h>
 #include <linux/crypto.h>
 #include <linux/kbuild.h>
+#include <linux/audit.h>
 #include <asm/mman.h>
+#include <asm/seccomp.h>
 
 /* workaround for a warning with -Wmissing-prototypes */
 void foo(void);
diff --git a/arch/x86/um/shared/sysdep/mcontext.h b/arch/x86/um/shared/sysdep/mcontext.h
index b724c54da3160..6fe490cc5b98a 100644
--- a/arch/x86/um/shared/sysdep/mcontext.h
+++ b/arch/x86/um/shared/sysdep/mcontext.h
@@ -6,7 +6,16 @@
 #ifndef __SYS_SIGCONTEXT_X86_H
 #define __SYS_SIGCONTEXT_X86_H
 
+#include <stub-data.h>
+
 extern void get_regs_from_mc(struct uml_pt_regs *, mcontext_t *);
+extern void get_mc_from_regs(struct uml_pt_regs *regs, mcontext_t *mc,
+			     int single_stepping);
+
+extern int get_stub_state(struct uml_pt_regs *regs, struct stub_data *data,
+			  unsigned long *fp_size_out);
+extern int set_stub_state(struct uml_pt_regs *regs, struct stub_data *data,
+			  int single_stepping);
 
 #ifdef __i386__
 
diff --git a/arch/x86/um/shared/sysdep/stub-data.h b/arch/x86/um/shared/sysdep/stub-data.h
new file mode 100644
index 0000000000000..82b1b7f8ac3d6
--- /dev/null
+++ b/arch/x86/um/shared/sysdep/stub-data.h
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ARCH_STUB_DATA_H
+#define __ARCH_STUB_DATA_H
+
+#ifdef __i386__
+#include <generated/asm-offsets.h>
+#include <asm/ldt.h>
+
+struct stub_data_arch {
+	int sync;
+	struct user_desc tls[UM_KERN_GDT_ENTRY_TLS_ENTRIES];
+};
+#else
+#define STUB_SYNC_FS_BASE (1 << 0)
+#define STUB_SYNC_GS_BASE (1 << 1)
+struct stub_data_arch {
+	int sync;
+	unsigned long fs_base;
+	unsigned long gs_base;
+};
+#endif
+
+#endif /* __ARCH_STUB_DATA_H */
diff --git a/arch/x86/um/shared/sysdep/stub.h b/arch/x86/um/shared/sysdep/stub.h
index dc89f44234546..4fa58f5b4fcaa 100644
--- a/arch/x86/um/shared/sysdep/stub.h
+++ b/arch/x86/um/shared/sysdep/stub.h
@@ -13,3 +13,5 @@
 
 extern void stub_segv_handler(int, siginfo_t *, void *);
 extern void stub_syscall_handler(void);
+extern void stub_signal_interrupt(int, siginfo_t *, void *);
+extern void stub_signal_restorer(void);
diff --git a/arch/x86/um/shared/sysdep/stub_32.h b/arch/x86/um/shared/sysdep/stub_32.h
index 390988132c0a7..df568fc3ceb41 100644
--- a/arch/x86/um/shared/sysdep/stub_32.h
+++ b/arch/x86/um/shared/sysdep/stub_32.h
@@ -131,4 +131,17 @@ static __always_inline void *get_stub_data(void)
 		"call *%%eax ;"						\
 		:: "i" ((1 + STUB_DATA_PAGES) * UM_KERN_PAGE_SIZE),	\
 		   "i" (&fn))
+
+static __always_inline void
+stub_seccomp_restore_state(struct stub_data_arch *arch)
+{
+	for (int i = 0; i < sizeof(arch->tls) / sizeof(arch->tls[0]); i++) {
+		if (arch->sync & (1 << i))
+			stub_syscall1(__NR_set_thread_area,
+				      (unsigned long) &arch->tls[i]);
+	}
+
+	arch->sync = 0;
+}
+
 #endif
diff --git a/arch/x86/um/shared/sysdep/stub_64.h b/arch/x86/um/shared/sysdep/stub_64.h
index 294affbec7429..9cfd31afa7699 100644
--- a/arch/x86/um/shared/sysdep/stub_64.h
+++ b/arch/x86/um/shared/sysdep/stub_64.h
@@ -10,6 +10,7 @@
 #include <sysdep/ptrace_user.h>
 #include <generated/asm-offsets.h>
 #include <linux/stddef.h>
+#include <asm/prctl.h>
 
 #define STUB_MMAP_NR __NR_mmap
 #define MMAP_OFFSET(o) (o)
@@ -134,4 +135,20 @@ static __always_inline void *get_stub_data(void)
 		"call *%%rax ;"						\
 		:: "i" ((1 + STUB_DATA_PAGES) * UM_KERN_PAGE_SIZE),	\
 		   "i" (&fn))
+
+static __always_inline void
+stub_seccomp_restore_state(struct stub_data_arch *arch)
+{
+	/*
+	 * We could use _writefsbase_u64/_writegsbase_u64 if the host reports
+	 * support in the hwcaps (HWCAP2_FSGSBASE).
+	 */
+	if (arch->sync & STUB_SYNC_FS_BASE)
+		stub_syscall2(__NR_arch_prctl, ARCH_SET_FS, arch->fs_base);
+	if (arch->sync & STUB_SYNC_GS_BASE)
+		stub_syscall2(__NR_arch_prctl, ARCH_SET_GS, arch->gs_base);
+
+	arch->sync = 0;
+}
+
 #endif