diff options
| -rw-r--r-- | arch/um/include/shared/as-layout.h | 2 | ||||
| -rw-r--r-- | arch/um/include/shared/os.h | 3 | ||||
| -rw-r--r-- | arch/um/kernel/um_arch.c | 21 | ||||
| -rw-r--r-- | arch/um/os-Linux/main.c | 9 | ||||
| -rw-r--r-- | arch/x86/um/os-Linux/Makefile | 2 | ||||
| -rw-r--r-- | arch/x86/um/os-Linux/task_size.c | 151 |
6 files changed, 29 insertions, 159 deletions
diff --git a/arch/um/include/shared/as-layout.h b/arch/um/include/shared/as-layout.h index 283226c34ca4..d9679c911e54 100644 --- a/arch/um/include/shared/as-layout.h +++ b/arch/um/include/shared/as-layout.h @@ -49,7 +49,7 @@ extern unsigned long brk_start; extern unsigned long host_task_size; extern unsigned long stub_start; -extern int linux_main(int argc, char **argv); +extern int linux_main(int argc, char **argv, char **envp); extern void uml_finishsetup(void); struct siginfo; diff --git a/arch/um/include/shared/os.h b/arch/um/include/shared/os.h index b511637e1f76..bf539fee7831 100644 --- a/arch/um/include/shared/os.h +++ b/arch/um/include/shared/os.h @@ -325,9 +325,6 @@ extern int __ignore_sigio_fd(int fd); /* tty.c */ extern int get_pty(void); -/* sys-$ARCH/task_size.c */ -extern unsigned long os_get_top_address(void); - long syscall(long number, ...); /* irqflags tracing */ diff --git a/arch/um/kernel/um_arch.c b/arch/um/kernel/um_arch.c index 4452df4f2c4b..38cbb41a64bc 100644 --- a/arch/um/kernel/um_arch.c +++ b/arch/um/kernel/um_arch.c @@ -302,7 +302,24 @@ static void parse_cache_line(char *line) } } -int __init linux_main(int argc, char **argv) +static unsigned long get_top_address(char **envp) +{ + unsigned long top_addr = (unsigned long) &top_addr; + int i; + + /* The earliest variable should be after the program name in ELF */ + for (i = 0; envp[i]; i++) { + if ((unsigned long) envp[i] > top_addr) + top_addr = (unsigned long) envp[i]; + } + + top_addr &= ~(UM_KERN_PAGE_SIZE - 1); + top_addr += UM_KERN_PAGE_SIZE; + + return top_addr; +} + +int __init linux_main(int argc, char **argv, char **envp) { unsigned long avail, diff; unsigned long virtmem_size, max_physmem; @@ -324,7 +341,7 @@ int __init linux_main(int argc, char **argv) if (have_console == 0) add_arg(DEFAULT_COMMAND_LINE_CONSOLE); - host_task_size = os_get_top_address(); + host_task_size = get_top_address(envp); /* reserve a few pages for the stubs */ stub_start = host_task_size - STUB_DATA_PAGES * PAGE_SIZE; /* another page for the code portion */ diff --git a/arch/um/os-Linux/main.c b/arch/um/os-Linux/main.c index cf1179ed1aec..8a52c49c5361 100644 --- a/arch/um/os-Linux/main.c +++ b/arch/um/os-Linux/main.c @@ -11,6 +11,7 @@ #include <signal.h> #include <string.h> #include <sys/resource.h> +#include <sys/personality.h> #include <as-layout.h> #include <init.h> #include <kern_util.h> @@ -108,6 +109,12 @@ int __init main(int argc, char **argv, char **envp) char **new_argv; int ret, i, err; + /* Disable randomization and re-exec if it was changed successfully */ + ret = personality(PER_LINUX | ADDR_NO_RANDOMIZE); + if (ret >= 0 && (ret & (PER_LINUX | ADDR_NO_RANDOMIZE)) != + (PER_LINUX | ADDR_NO_RANDOMIZE)) + execve("/proc/self/exe", argv, envp); + set_stklim(); setup_env_path(); @@ -140,7 +147,7 @@ int __init main(int argc, char **argv, char **envp) #endif change_sig(SIGPIPE, 0); - ret = linux_main(argc, argv); + ret = linux_main(argc, argv, envp); /* * Disable SIGPROF - I have no idea why libc doesn't do this or turn diff --git a/arch/x86/um/os-Linux/Makefile b/arch/x86/um/os-Linux/Makefile index 5249bbc30dcd..77a308aaa5ec 100644 --- a/arch/x86/um/os-Linux/Makefile +++ b/arch/x86/um/os-Linux/Makefile @@ -3,7 +3,7 @@ # Licensed under the GPL # -obj-y = registers.o task_size.o mcontext.o +obj-y = registers.o mcontext.o obj-$(CONFIG_X86_32) += tls.o diff --git a/arch/x86/um/os-Linux/task_size.c b/arch/x86/um/os-Linux/task_size.c deleted file mode 100644 index 1dc9adc20b1c..000000000000 --- a/arch/x86/um/os-Linux/task_size.c +++ /dev/null @@ -1,151 +0,0 @@ -// SPDX-License-Identifier: GPL-2.0 -#include <stdio.h> -#include <stdlib.h> -#include <signal.h> -#include <sys/mman.h> -#include <longjmp.h> - -#ifdef __i386__ - -static jmp_buf buf; - -static void segfault(int sig) -{ - longjmp(buf, 1); -} - -static int page_ok(unsigned long page) -{ - unsigned long *address = (unsigned long *) (page << UM_KERN_PAGE_SHIFT); - unsigned long n = ~0UL; - void *mapped = NULL; - int ok = 0; - - /* - * First see if the page is readable. If it is, it may still - * be a VDSO, so we go on to see if it's writable. If not - * then try mapping memory there. If that fails, then we're - * still in the kernel area. As a sanity check, we'll fail if - * the mmap succeeds, but gives us an address different from - * what we wanted. - */ - if (setjmp(buf) == 0) - n = *address; - else { - mapped = mmap(address, UM_KERN_PAGE_SIZE, - PROT_READ | PROT_WRITE, - MAP_FIXED | MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); - if (mapped == MAP_FAILED) - return 0; - if (mapped != address) - goto out; - } - - /* - * Now, is it writeable? If so, then we're in user address - * space. If not, then try mprotecting it and try the write - * again. - */ - if (setjmp(buf) == 0) { - *address = n; - ok = 1; - goto out; - } else if (mprotect(address, UM_KERN_PAGE_SIZE, - PROT_READ | PROT_WRITE) != 0) - goto out; - - if (setjmp(buf) == 0) { - *address = n; - ok = 1; - } - - out: - if (mapped != NULL) - munmap(mapped, UM_KERN_PAGE_SIZE); - return ok; -} - -unsigned long os_get_top_address(void) -{ - struct sigaction sa, old; - unsigned long bottom = 0; - /* - * A 32-bit UML on a 64-bit host gets confused about the VDSO at - * 0xffffe000. It is mapped, is readable, can be reprotected writeable - * and written. However, exec discovers later that it can't be - * unmapped. So, just set the highest address to be checked to just - * below it. This might waste some address space on 4G/4G 32-bit - * hosts, but shouldn't hurt otherwise. - */ - unsigned long top = 0xffffd000 >> UM_KERN_PAGE_SHIFT; - unsigned long test, original; - - printf("Locating the bottom of the address space ... "); - fflush(stdout); - - /* - * We're going to be longjmping out of the signal handler, so - * SA_DEFER needs to be set. - */ - sa.sa_handler = segfault; - sigemptyset(&sa.sa_mask); - sa.sa_flags = SA_NODEFER; - if (sigaction(SIGSEGV, &sa, &old)) { - perror("os_get_top_address"); - exit(1); - } - - /* Manually scan the address space, bottom-up, until we find - * the first valid page (or run out of them). - */ - for (bottom = 0; bottom < top; bottom++) { - if (page_ok(bottom)) - break; - } - - /* If we've got this far, we ran out of pages. */ - if (bottom == top) { - fprintf(stderr, "Unable to determine bottom of address " - "space.\n"); - exit(1); - } - - printf("0x%lx\n", bottom << UM_KERN_PAGE_SHIFT); - printf("Locating the top of the address space ... "); - fflush(stdout); - - original = bottom; - - /* This could happen with a 4G/4G split */ - if (page_ok(top)) - goto out; - - do { - test = bottom + (top - bottom) / 2; - if (page_ok(test)) - bottom = test; - else - top = test; - } while (top - bottom > 1); - -out: - /* Restore the old SIGSEGV handling */ - if (sigaction(SIGSEGV, &old, NULL)) { - perror("os_get_top_address"); - exit(1); - } - top <<= UM_KERN_PAGE_SHIFT; - printf("0x%lx\n", top); - - return top; -} - -#else - -unsigned long os_get_top_address(void) -{ - /* The old value of CONFIG_TOP_ADDR */ - return 0x7fc0002000; -} - -#endif |