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authorLinus Torvalds <torvalds@linux-foundation.org>2023-05-03 19:02:03 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2023-05-03 19:02:03 -0700
commit342528ff00e8a7dd31c1ea0c0093c2289d769b39 (patch)
tree1cbc0211a984e2729d42ebce4537ff1074df46e7 /arch/um
parent9f2692326b9c6db8d0e866d555606b12a507a363 (diff)
parent6032aca0deb9c138df122192f8ef02de1fdccf25 (diff)
Merge tag 'uml-for-linus-6.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux
Pull uml updates from Richard Weinberger: - Make stub data pages configurable - Make it harder to mix user and kernel code by accident * tag 'uml-for-linus-6.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux: um: make stub data pages size tweakable um: prevent user code in modules um: further clean up user_syms um: don't export printf() um: hostfs: define our own API boundary um: add __weak for exported functions
Diffstat (limited to 'arch/um')
-rw-r--r--arch/um/include/shared/as-layout.h3
-rw-r--r--arch/um/kernel/skas/clone.c5
-rw-r--r--arch/um/kernel/skas/mmu.c6
-rw-r--r--arch/um/kernel/um_arch.c10
-rw-r--r--arch/um/os-Linux/skas/process.c6
-rw-r--r--arch/um/os-Linux/user_syms.c104
-rw-r--r--arch/um/scripts/Makefile.rules4
7 files changed, 36 insertions, 102 deletions
diff --git a/arch/um/include/shared/as-layout.h b/arch/um/include/shared/as-layout.h
index 9a0bd648d872..9ec3015bc5e2 100644
--- a/arch/um/include/shared/as-layout.h
+++ b/arch/um/include/shared/as-layout.h
@@ -23,7 +23,8 @@
#define STUB_START stub_start
#define STUB_CODE STUB_START
#define STUB_DATA (STUB_CODE + UM_KERN_PAGE_SIZE)
-#define STUB_END (STUB_DATA + UM_KERN_PAGE_SIZE)
+#define STUB_DATA_PAGES 1 /* must be a power of two */
+#define STUB_END (STUB_DATA + STUB_DATA_PAGES * UM_KERN_PAGE_SIZE)
#ifndef __ASSEMBLY__
diff --git a/arch/um/kernel/skas/clone.c b/arch/um/kernel/skas/clone.c
index ff5061f29167..62435187dda4 100644
--- a/arch/um/kernel/skas/clone.c
+++ b/arch/um/kernel/skas/clone.c
@@ -24,11 +24,12 @@
void __attribute__ ((__section__ (".__syscall_stub")))
stub_clone_handler(void)
{
- struct stub_data *data = get_stub_page();
+ struct stub_data *data = get_stub_data();
long err;
err = stub_syscall2(__NR_clone, CLONE_PARENT | CLONE_FILES | SIGCHLD,
- (unsigned long)data + UM_KERN_PAGE_SIZE / 2);
+ (unsigned long)data +
+ STUB_DATA_PAGES * UM_KERN_PAGE_SIZE / 2);
if (err) {
data->parent_err = err;
goto done;
diff --git a/arch/um/kernel/skas/mmu.c b/arch/um/kernel/skas/mmu.c
index 125df465e8ea..656fe16c9b63 100644
--- a/arch/um/kernel/skas/mmu.c
+++ b/arch/um/kernel/skas/mmu.c
@@ -21,7 +21,7 @@ int init_new_context(struct task_struct *task, struct mm_struct *mm)
unsigned long stack = 0;
int ret = -ENOMEM;
- stack = get_zeroed_page(GFP_KERNEL);
+ stack = __get_free_pages(GFP_KERNEL | __GFP_ZERO, ilog2(STUB_DATA_PAGES));
if (stack == 0)
goto out;
@@ -52,7 +52,7 @@ int init_new_context(struct task_struct *task, struct mm_struct *mm)
out_free:
if (to_mm->id.stack != 0)
- free_page(to_mm->id.stack);
+ free_pages(to_mm->id.stack, ilog2(STUB_DATA_PAGES));
out:
return ret;
}
@@ -74,6 +74,6 @@ void destroy_context(struct mm_struct *mm)
}
os_kill_ptraced_process(mmu->id.u.pid, 1);
- free_page(mmu->id.stack);
+ free_pages(mmu->id.stack, ilog2(STUB_DATA_PAGES));
free_ldt(mmu);
}
diff --git a/arch/um/kernel/um_arch.c b/arch/um/kernel/um_arch.c
index 8dcda617b8bf..0a23a98d4ca0 100644
--- a/arch/um/kernel/um_arch.c
+++ b/arch/um/kernel/um_arch.c
@@ -326,9 +326,13 @@ int __init linux_main(int argc, char **argv)
add_arg(DEFAULT_COMMAND_LINE_CONSOLE);
host_task_size = os_get_top_address();
- /* reserve two pages for the stubs */
- host_task_size -= 2 * PAGE_SIZE;
- stub_start = host_task_size;
+ /* reserve a few pages for the stubs (taking care of data alignment) */
+ /* align the data portion */
+ BUILD_BUG_ON(!is_power_of_2(STUB_DATA_PAGES));
+ stub_start = (host_task_size - 1) & ~(STUB_DATA_PAGES * PAGE_SIZE - 1);
+ /* another page for the code portion */
+ stub_start -= PAGE_SIZE;
+ host_task_size = stub_start;
/*
* TASK_SIZE needs to be PGDIR_SIZE aligned or else exit_mmap craps
diff --git a/arch/um/os-Linux/skas/process.c b/arch/um/os-Linux/skas/process.c
index b1ea53285af1..9464833e741a 100644
--- a/arch/um/os-Linux/skas/process.c
+++ b/arch/um/os-Linux/skas/process.c
@@ -262,7 +262,7 @@ static int userspace_tramp(void *stack)
if (stack != NULL) {
fd = phys_mapping(uml_to_phys(stack), &offset);
addr = mmap((void *) STUB_DATA,
- UM_KERN_PAGE_SIZE, PROT_READ | PROT_WRITE,
+ STUB_DATA_PAGES * UM_KERN_PAGE_SIZE, PROT_READ | PROT_WRITE,
MAP_FIXED | MAP_SHARED, fd, offset);
if (addr == MAP_FAILED) {
printk(UM_KERN_ERR "mapping segfault stack at 0x%lx failed, errno = %d\n",
@@ -277,7 +277,7 @@ static int userspace_tramp(void *stack)
(unsigned long) stub_segv_handler -
(unsigned long) __syscall_stub_start;
- set_sigstack((void *) STUB_DATA, UM_KERN_PAGE_SIZE);
+ set_sigstack((void *) STUB_DATA, STUB_DATA_PAGES * UM_KERN_PAGE_SIZE);
sigemptyset(&sa.sa_mask);
sa.sa_flags = SA_ONSTACK | SA_NODEFER | SA_SIGINFO;
sa.sa_sigaction = (void *) v;
@@ -515,7 +515,7 @@ static int __init init_thread_regs(void)
thread_regs[REGS_IP_INDEX] = STUB_CODE +
(unsigned long) stub_clone_handler -
(unsigned long) __syscall_stub_start;
- thread_regs[REGS_SP_INDEX] = STUB_DATA + UM_KERN_PAGE_SIZE -
+ thread_regs[REGS_SP_INDEX] = STUB_DATA + STUB_DATA_PAGES * UM_KERN_PAGE_SIZE -
sizeof(void *);
#ifdef __SIGNAL_FRAMESIZE
thread_regs[REGS_SP_INDEX] -= __SIGNAL_FRAMESIZE;
diff --git a/arch/um/os-Linux/user_syms.c b/arch/um/os-Linux/user_syms.c
index fd575ecbcaec..9b62a9d352b3 100644
--- a/arch/um/os-Linux/user_syms.c
+++ b/arch/um/os-Linux/user_syms.c
@@ -3,112 +3,40 @@
#include <linux/types.h>
#include <linux/module.h>
-/* Some of this are builtin function (some are not but could in the future),
- * so I *must* declare good prototypes for them and then EXPORT them.
- * The kernel code uses the macro defined by include/linux/string.h,
- * so I undef macros; the userspace code does not include that and I
- * add an EXPORT for the glibc one.
+/*
+ * This file exports some critical string functions and compiler
+ * built-in functions (where calls are emitted by the compiler
+ * itself that we cannot avoid even in kernel code) to modules.
+ *
+ * "_user.c" code that previously used exports here such as hostfs
+ * really should be considered part of the 'hypervisor' and define
+ * its own API boundary like hostfs does now; don't add exports to
+ * this file for such cases.
*/
-#undef strlen
-#undef strstr
-#undef memcpy
-#undef memset
-
-extern size_t strlen(const char *);
-extern void *memmove(void *, const void *, size_t);
-extern void *memset(void *, int, size_t);
-extern int printf(const char *, ...);
-
/* If it's not defined, the export is included in lib/string.c.*/
#ifdef __HAVE_ARCH_STRSTR
+#undef strstr
EXPORT_SYMBOL(strstr);
#endif
#ifndef __x86_64__
+#undef memcpy
extern void *memcpy(void *, const void *, size_t);
EXPORT_SYMBOL(memcpy);
+extern void *memmove(void *, const void *, size_t);
EXPORT_SYMBOL(memmove);
+#undef memset
+extern void *memset(void *, int, size_t);
EXPORT_SYMBOL(memset);
#endif
-EXPORT_SYMBOL(printf);
-
-/* Here, instead, I can provide a fake prototype. Yes, someone cares: genksyms.
- * However, the modules will use the CRC defined *here*, no matter if it is
- * good; so the versions of these symbols will always match
- */
-#define EXPORT_SYMBOL_PROTO(sym) \
- int sym(void); \
- EXPORT_SYMBOL(sym);
-
-extern void readdir64(void) __attribute__((weak));
-EXPORT_SYMBOL(readdir64);
-extern void truncate64(void) __attribute__((weak));
-EXPORT_SYMBOL(truncate64);
-
#ifdef CONFIG_ARCH_REUSE_HOST_VSYSCALL_AREA
+/* needed for __access_ok() */
EXPORT_SYMBOL(vsyscall_ehdr);
EXPORT_SYMBOL(vsyscall_end);
#endif
-EXPORT_SYMBOL_PROTO(__errno_location);
-
-EXPORT_SYMBOL_PROTO(access);
-EXPORT_SYMBOL_PROTO(open);
-EXPORT_SYMBOL_PROTO(open64);
-EXPORT_SYMBOL_PROTO(close);
-EXPORT_SYMBOL_PROTO(read);
-EXPORT_SYMBOL_PROTO(write);
-EXPORT_SYMBOL_PROTO(dup2);
-EXPORT_SYMBOL_PROTO(__xstat);
-EXPORT_SYMBOL_PROTO(__lxstat);
-EXPORT_SYMBOL_PROTO(__lxstat64);
-EXPORT_SYMBOL_PROTO(__fxstat64);
-EXPORT_SYMBOL_PROTO(lseek);
-EXPORT_SYMBOL_PROTO(lseek64);
-EXPORT_SYMBOL_PROTO(chown);
-EXPORT_SYMBOL_PROTO(fchown);
-EXPORT_SYMBOL_PROTO(truncate);
-EXPORT_SYMBOL_PROTO(ftruncate64);
-EXPORT_SYMBOL_PROTO(utime);
-EXPORT_SYMBOL_PROTO(utimes);
-EXPORT_SYMBOL_PROTO(futimes);
-EXPORT_SYMBOL_PROTO(chmod);
-EXPORT_SYMBOL_PROTO(fchmod);
-EXPORT_SYMBOL_PROTO(rename);
-EXPORT_SYMBOL_PROTO(__xmknod);
-
-EXPORT_SYMBOL_PROTO(symlink);
-EXPORT_SYMBOL_PROTO(link);
-EXPORT_SYMBOL_PROTO(unlink);
-EXPORT_SYMBOL_PROTO(readlink);
-
-EXPORT_SYMBOL_PROTO(mkdir);
-EXPORT_SYMBOL_PROTO(rmdir);
-EXPORT_SYMBOL_PROTO(opendir);
-EXPORT_SYMBOL_PROTO(readdir);
-EXPORT_SYMBOL_PROTO(closedir);
-EXPORT_SYMBOL_PROTO(seekdir);
-EXPORT_SYMBOL_PROTO(telldir);
-
-EXPORT_SYMBOL_PROTO(ioctl);
-
-EXPORT_SYMBOL_PROTO(pread64);
-EXPORT_SYMBOL_PROTO(pwrite64);
-
-EXPORT_SYMBOL_PROTO(statfs);
-EXPORT_SYMBOL_PROTO(statfs64);
-
-EXPORT_SYMBOL_PROTO(getuid);
-
-EXPORT_SYMBOL_PROTO(fsync);
-EXPORT_SYMBOL_PROTO(fdatasync);
-
-EXPORT_SYMBOL_PROTO(lstat64);
-EXPORT_SYMBOL_PROTO(fstat64);
-EXPORT_SYMBOL_PROTO(mknod);
-
/* Export symbols used by GCC for the stack protector. */
extern void __stack_smash_handler(void *) __attribute__((weak));
EXPORT_SYMBOL(__stack_smash_handler);
@@ -117,6 +45,6 @@ extern long __guard __attribute__((weak));
EXPORT_SYMBOL(__guard);
#ifdef _FORTIFY_SOURCE
-extern int __sprintf_chk(char *str, int flag, size_t strlen, const char *format);
+extern int __sprintf_chk(char *str, int flag, size_t len, const char *format);
EXPORT_SYMBOL(__sprintf_chk);
#endif
diff --git a/arch/um/scripts/Makefile.rules b/arch/um/scripts/Makefile.rules
index a4dfa7d7636e..a8b7d9dab0a6 100644
--- a/arch/um/scripts/Makefile.rules
+++ b/arch/um/scripts/Makefile.rules
@@ -4,8 +4,8 @@
# ===========================================================================
USER_SINGLE_OBJS := \
- $(foreach f,$(patsubst %.o,%,$(obj-y) $(obj-m)),$($(f)-objs))
-USER_OBJS += $(filter %_user.o,$(obj-y) $(obj-m) $(USER_SINGLE_OBJS))
+ $(foreach f,$(patsubst %.o,%,$(obj-y)),$($(f)-objs))
+USER_OBJS += $(filter %_user.o,$(obj-y) $(USER_SINGLE_OBJS))
USER_OBJS := $(foreach file,$(USER_OBJS),$(obj)/$(file))
$(USER_OBJS:.o=.%): \