Message ID | e024234e652f23be4d76d63227de114e7def5dff.1560339705.git.andreyknvl@google.com (mailing list archive) |
---|---|
State | New |
Headers | show |
Series | arm64: untag user pointers passed to the kernel | expand |
On 12/06/2019 12:43, Andrey Konovalov wrote: > --- /dev/null > +++ b/tools/testing/selftests/arm64/tags_lib.c > @@ -0,0 +1,62 @@ > +// SPDX-License-Identifier: GPL-2.0 > + > +#include <stdlib.h> > +#include <sys/prctl.h> > + > +#define TAG_SHIFT (56) > +#define TAG_MASK (0xffUL << TAG_SHIFT) > + > +#define PR_SET_TAGGED_ADDR_CTRL 55 > +#define PR_GET_TAGGED_ADDR_CTRL 56 > +#define PR_TAGGED_ADDR_ENABLE (1UL << 0) > + > +void *__libc_malloc(size_t size); > +void __libc_free(void *ptr); > +void *__libc_realloc(void *ptr, size_t size); > +void *__libc_calloc(size_t nmemb, size_t size); this does not work on at least musl. the most robust solution would be to implement the malloc apis with mmap/munmap/mremap, if that's too cumbersome then use dlsym RTLD_NEXT (although that has the slight wart that in glibc it may call calloc so wrapping calloc that way is tricky). in simple linux tests i'd just use static or stack allocations or mmap. if a generic preloadable lib solution is needed then do it properly with pthread_once to avoid races etc. > + > +static void *tag_ptr(void *ptr) > +{ > + static int tagged_addr_err = 1; > + unsigned long tag = 0; > + > + /* > + * Note that this code is racy. We only use it as a part of a single > + * threaded test application. Beware of using in multithreaded ones. > + */ > + if (tagged_addr_err == 1) > + tagged_addr_err = prctl(PR_SET_TAGGED_ADDR_CTRL, > + PR_TAGGED_ADDR_ENABLE, 0, 0, 0); > + > + if (!ptr) > + return ptr; > + if (!tagged_addr_err) > + tag = rand() & 0xff; > + > + return (void *)((unsigned long)ptr | (tag << TAG_SHIFT)); > +} > + > +static void *untag_ptr(void *ptr) > +{ > + return (void *)((unsigned long)ptr & ~TAG_MASK); > +} > + > +void *malloc(size_t size) > +{ > + return tag_ptr(__libc_malloc(size)); > +} ...
diff --git a/tools/testing/selftests/arm64/.gitignore b/tools/testing/selftests/arm64/.gitignore new file mode 100644 index 000000000000..9b6a568de17f --- /dev/null +++ b/tools/testing/selftests/arm64/.gitignore @@ -0,0 +1,2 @@ +tags_test +tags_lib.so diff --git a/tools/testing/selftests/arm64/Makefile b/tools/testing/selftests/arm64/Makefile new file mode 100644 index 000000000000..9dee18727923 --- /dev/null +++ b/tools/testing/selftests/arm64/Makefile @@ -0,0 +1,22 @@ +# SPDX-License-Identifier: GPL-2.0 + +include ../lib.mk + +# ARCH can be overridden by the user for cross compiling +ARCH ?= $(shell uname -m 2>/dev/null || echo not) + +ifneq (,$(filter $(ARCH),aarch64 arm64)) + +TEST_CUSTOM_PROGS := $(OUTPUT)/tags_test + +$(OUTPUT)/tags_test: tags_test.c $(OUTPUT)/tags_lib.so + $(CC) -o $@ $(CFLAGS) $(LDFLAGS) $< + +$(OUTPUT)/tags_lib.so: tags_lib.c + $(CC) -o $@ -shared $(CFLAGS) $(LDFLAGS) $^ + +TEST_PROGS := run_tags_test.sh + +all: $(TEST_CUSTOM_PROGS) + +endif diff --git a/tools/testing/selftests/arm64/run_tags_test.sh b/tools/testing/selftests/arm64/run_tags_test.sh new file mode 100755 index 000000000000..2bbe0cd4220b --- /dev/null +++ b/tools/testing/selftests/arm64/run_tags_test.sh @@ -0,0 +1,12 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 + +echo "--------------------" +echo "running tags test" +echo "--------------------" +LD_PRELOAD=./tags_lib.so ./tags_test +if [ $? -ne 0 ]; then + echo "[FAIL]" +else + echo "[PASS]" +fi diff --git a/tools/testing/selftests/arm64/tags_lib.c b/tools/testing/selftests/arm64/tags_lib.c new file mode 100644 index 000000000000..55f64fc1aae6 --- /dev/null +++ b/tools/testing/selftests/arm64/tags_lib.c @@ -0,0 +1,62 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include <stdlib.h> +#include <sys/prctl.h> + +#define TAG_SHIFT (56) +#define TAG_MASK (0xffUL << TAG_SHIFT) + +#define PR_SET_TAGGED_ADDR_CTRL 55 +#define PR_GET_TAGGED_ADDR_CTRL 56 +#define PR_TAGGED_ADDR_ENABLE (1UL << 0) + +void *__libc_malloc(size_t size); +void __libc_free(void *ptr); +void *__libc_realloc(void *ptr, size_t size); +void *__libc_calloc(size_t nmemb, size_t size); + +static void *tag_ptr(void *ptr) +{ + static int tagged_addr_err = 1; + unsigned long tag = 0; + + /* + * Note that this code is racy. We only use it as a part of a single + * threaded test application. Beware of using in multithreaded ones. + */ + if (tagged_addr_err == 1) + tagged_addr_err = prctl(PR_SET_TAGGED_ADDR_CTRL, + PR_TAGGED_ADDR_ENABLE, 0, 0, 0); + + if (!ptr) + return ptr; + if (!tagged_addr_err) + tag = rand() & 0xff; + + return (void *)((unsigned long)ptr | (tag << TAG_SHIFT)); +} + +static void *untag_ptr(void *ptr) +{ + return (void *)((unsigned long)ptr & ~TAG_MASK); +} + +void *malloc(size_t size) +{ + return tag_ptr(__libc_malloc(size)); +} + +void free(void *ptr) +{ + __libc_free(untag_ptr(ptr)); +} + +void *realloc(void *ptr, size_t size) +{ + return tag_ptr(__libc_realloc(untag_ptr(ptr), size)); +} + +void *calloc(size_t nmemb, size_t size) +{ + return tag_ptr(__libc_calloc(nmemb, size)); +} diff --git a/tools/testing/selftests/arm64/tags_test.c b/tools/testing/selftests/arm64/tags_test.c new file mode 100644 index 000000000000..263b302874ed --- /dev/null +++ b/tools/testing/selftests/arm64/tags_test.c @@ -0,0 +1,18 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include <stdio.h> +#include <stdlib.h> +#include <unistd.h> +#include <stdint.h> +#include <sys/utsname.h> + +int main(void) +{ + struct utsname *ptr; + int err; + + ptr = (struct utsname *)malloc(sizeof(*ptr)); + err = uname(ptr); + free(ptr); + return err; +}
This patch is a part of a series that extends arm64 kernel ABI to allow to pass tagged user pointers (with the top byte set to something else other than 0x00) as syscall arguments. This patch adds a simple test, that calls the uname syscall with a tagged user pointer as an argument. Without the kernel accepting tagged user pointers the test fails with EFAULT. Co-developed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Andrey Konovalov <andreyknvl@google.com> --- tools/testing/selftests/arm64/.gitignore | 2 + tools/testing/selftests/arm64/Makefile | 22 +++++++ .../testing/selftests/arm64/run_tags_test.sh | 12 ++++ tools/testing/selftests/arm64/tags_lib.c | 62 +++++++++++++++++++ tools/testing/selftests/arm64/tags_test.c | 18 ++++++ 5 files changed, 116 insertions(+) create mode 100644 tools/testing/selftests/arm64/.gitignore create mode 100644 tools/testing/selftests/arm64/Makefile create mode 100755 tools/testing/selftests/arm64/run_tags_test.sh create mode 100644 tools/testing/selftests/arm64/tags_lib.c create mode 100644 tools/testing/selftests/arm64/tags_test.c