[PATCH v2] elf: Define DEFAULT_STACK_PERMS to (PF_R|PF_W)
H.J. Lu
hjl.tools@gmail.com
Thu Jun 13 07:09:41 GMT 2024
Add stackperms.h to define DEFAULT_STACK_PERMS to (PF_R|PF_W) to disable
executable stack by default.
Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
---
elf/Makefile | 11 ++++++++++
elf/dl-load.c | 6 +-----
elf/dl-support.c | 2 +-
elf/rtld.c | 2 +-
elf/tst-execstack-mod2.c | 1 +
elf/tst-execstack2.c | 39 ++++++++++++++++++++++++++++++++++
support/support_stack_alloc.c | 10 +++++++--
sysdeps/aarch64/stackinfo.h | 3 ---
sysdeps/alpha/stackinfo.h | 4 ----
sysdeps/arc/stackinfo.h | 3 ---
sysdeps/arm/stackinfo.h | 4 ----
sysdeps/csky/stackinfo.h | 2 --
sysdeps/generic/stackperms.h | 25 ++++++++++++++++++++++
sysdeps/hppa/stackinfo.h | 4 ----
sysdeps/i386/stackinfo.h | 4 ----
sysdeps/loongarch/stackinfo.h | 3 ---
sysdeps/m68k/stackinfo.h | 4 ----
sysdeps/microblaze/stackinfo.h | 4 ----
sysdeps/mips/stackinfo.h | 4 ----
sysdeps/nios2/stackinfo.h | 3 ---
sysdeps/or1k/stackinfo.h | 4 ----
sysdeps/powerpc/stackinfo.h | 9 --------
sysdeps/riscv/stackinfo.h | 3 ---
sysdeps/s390/stackinfo.h | 4 ----
sysdeps/sh/stackinfo.h | 4 ----
sysdeps/sparc/stackinfo.h | 4 ----
sysdeps/x86_64/stackinfo.h | 4 ----
27 files changed, 87 insertions(+), 83 deletions(-)
create mode 100644 elf/tst-execstack-mod2.c
create mode 100644 elf/tst-execstack2.c
create mode 100644 sysdeps/generic/stackperms.h
diff --git a/elf/Makefile b/elf/Makefile
index 57b3a19d36..9bc1e3272d 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -420,6 +420,7 @@ tests += \
tst-dlopenfail-2 \
tst-dlopenrpath \
tst-dlsym-error \
+ tst-execstack2 \
tst-filterobj \
tst-filterobj-dlopen \
tst-glibc-hwcaps \
@@ -1858,6 +1859,16 @@ CFLAGS-tst-execstack-prog.c += -Wno-trampolines
CFLAGS-tst-execstack-mod.c += -Wno-trampolines
endif
+extra-test-objs += tst-execstack-mod2.os
+CFLAGS-tst-execstack-mod2.c += $(no-stack-protector)
+$(objpfx)tst-execstack2.out: $(objpfx)tst-execstack-mod2-default.so
+# Don't generate PT_GNU_STACK segment to verify DEFAULT_STACK_PERMS.
+$(objpfx)tst-execstack-mod2-default.so: $(objpfx)tst-execstack-mod2.os
+ $(OBJCOPY) -R .note.GNU-stack $^ $^T
+ $(CC) -nostdlib -nostartfiles -shared -o $@.new $^T
+ $(call after-link,$@.new)
+ mv -f $@.new $@
+
LDFLAGS-tst-array2 = -Wl,--no-as-needed
LDFLAGS-tst-array5 = -Wl,--no-as-needed
diff --git a/elf/dl-load.c b/elf/dl-load.c
index 8a89b71016..77526a1434 100644
--- a/elf/dl-load.c
+++ b/elf/dl-load.c
@@ -61,7 +61,6 @@ struct filebuf
#include "dynamic-link.h"
#include "get-dynamic-info.h"
#include <abi-tag.h>
-#include <stackinfo.h>
#include <sysdep.h>
#include <stap-probe.h>
#include <libc-pointer-arith.h>
@@ -1069,10 +1068,7 @@ _dl_map_object_from_fd (const char *name, const char *origname, int fd,
}
}
- /* On most platforms presume that PT_GNU_STACK is absent and the stack is
- * executable. Other platforms default to a nonexecutable stack and don't
- * need PT_GNU_STACK to do so. */
- unsigned int stack_flags = DEFAULT_STACK_PERMS;
+ unsigned int stack_flags = GL(dl_stack_flags);
{
/* Scan the program header table, collecting its load commands. */
diff --git a/elf/dl-support.c b/elf/dl-support.c
index 451932dd03..1f349978b1 100644
--- a/elf/dl-support.c
+++ b/elf/dl-support.c
@@ -38,7 +38,7 @@
#include <dl-procinfo.h>
#include <unsecvars.h>
#include <hp-timing.h>
-#include <stackinfo.h>
+#include <stackperms.h>
#include <dl-vdso.h>
#include <dl-vdso-setup.h>
#include <dl-auxv.h>
diff --git a/elf/rtld.c b/elf/rtld.c
index e9525ea987..fba0e6bc00 100644
--- a/elf/rtld.c
+++ b/elf/rtld.c
@@ -41,7 +41,7 @@
#include <dl-vdso-setup.h>
#include <tls.h>
#include <stap-probe.h>
-#include <stackinfo.h>
+#include <stackperms.h>
#include <not-cancel.h>
#include <array_length.h>
#include <libc-early-init.h>
diff --git a/elf/tst-execstack-mod2.c b/elf/tst-execstack-mod2.c
new file mode 100644
index 0000000000..3c8397fb8f
--- /dev/null
+++ b/elf/tst-execstack-mod2.c
@@ -0,0 +1 @@
+#include "tst-execstack-mod.c"
diff --git a/elf/tst-execstack2.c b/elf/tst-execstack2.c
new file mode 100644
index 0000000000..66217886bb
--- /dev/null
+++ b/elf/tst-execstack2.c
@@ -0,0 +1,39 @@
+/* Test calling a function, which requires executable stack, in a dlopened
+ DSO without PT_GNU_STACK segment.
+ Copyright (C) 2024 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+#include <stdlib.h>
+#include <signal.h>
+#include <support/xdlfcn.h>
+
+static int
+do_test (void)
+{
+ const char *soname = "tst-execstack-mod2-default.so";
+ void *h = xdlopen (soname, RTLD_LAZY);
+
+ void *f = xdlsym (h, "tryme");
+
+ /* This should segfault. */
+ (*((void (*) (void)) f)) ();
+
+ return EXIT_FAILURE;
+}
+
+#define EXPECTED_SIGNAL SIGSEGV
+#include <support/test-driver.c>
diff --git a/support/support_stack_alloc.c b/support/support_stack_alloc.c
index edf3dbfc21..762d9ab3bf 100644
--- a/support/support_stack_alloc.c
+++ b/support/support_stack_alloc.c
@@ -21,10 +21,16 @@
#include <support/xunistd.h>
#include <stdint.h>
#include <string.h>
-#include <stackinfo.h>
+#include <elf.h>
#include <sys/mman.h>
#include <sys/param.h> /* roundup, MAX */
+/* Get GL(dl_stack_flags). NB: This only works with dynamic tests. */
+#undef SHARED
+#define SHARED
+#include <ldsodefs.h>
+#undef SHARED
+
#ifndef MAP_NORESERVE
# define MAP_NORESERVE 0
#endif
@@ -68,7 +74,7 @@ support_stack_alloc (size_t size)
However since glibc does not export such information with a proper ABI,
it uses the historical permissions. */
int prot = PROT_READ | PROT_WRITE
- | (DEFAULT_STACK_PERMS & PF_X ? PROT_EXEC : 0);
+ | (GL(dl_stack_flags) & PF_X ? PROT_EXEC : 0);
xmprotect (alloc_base + guardsize, stacksize, prot);
memset (alloc_base + guardsize, 0xA5, stacksize);
return (struct support_stack) { alloc_base + guardsize, stacksize, guardsize };
diff --git a/sysdeps/aarch64/stackinfo.h b/sysdeps/aarch64/stackinfo.h
index 5a4dce7309..c1fbf08298 100644
--- a/sysdeps/aarch64/stackinfo.h
+++ b/sysdeps/aarch64/stackinfo.h
@@ -27,7 +27,4 @@
/* On AArch64 the stack grows down. */
#define _STACK_GROWS_DOWN 1
-/* Default to a non-executable stack. */
-#define DEFAULT_STACK_PERMS (PF_R|PF_W)
-
#endif /* stackinfo.h */
diff --git a/sysdeps/alpha/stackinfo.h b/sysdeps/alpha/stackinfo.h
index d45c280cb8..3bae7f2fc7 100644
--- a/sysdeps/alpha/stackinfo.h
+++ b/sysdeps/alpha/stackinfo.h
@@ -26,8 +26,4 @@
/* On Alpha the stack grows down. */
#define _STACK_GROWS_DOWN 1
-/* Default to an executable stack. PF_X can be overridden if PT_GNU_STACK is
- * present, but it is presumed absent. */
-#define DEFAULT_STACK_PERMS (PF_R|PF_W|PF_X)
-
#endif /* stackinfo.h */
diff --git a/sysdeps/arc/stackinfo.h b/sysdeps/arc/stackinfo.h
index 99a7f56ea0..dd20edc78d 100644
--- a/sysdeps/arc/stackinfo.h
+++ b/sysdeps/arc/stackinfo.h
@@ -27,7 +27,4 @@
/* On ARC the stack grows down. */
#define _STACK_GROWS_DOWN 1
-/* Default to a non-executable stack. */
-#define DEFAULT_STACK_PERMS (PF_R|PF_W)
-
#endif /* stackinfo.h */
diff --git a/sysdeps/arm/stackinfo.h b/sysdeps/arm/stackinfo.h
index 6ef3b5e316..1cac24d6f6 100644
--- a/sysdeps/arm/stackinfo.h
+++ b/sysdeps/arm/stackinfo.h
@@ -26,8 +26,4 @@
/* On Arm the stack grows down. */
#define _STACK_GROWS_DOWN 1
-/* Default to an executable stack. PF_X can be overridden if PT_GNU_STACK is
- * present, but it is presumed absent. */
-#define DEFAULT_STACK_PERMS (PF_R|PF_W|PF_X)
-
#endif /* stackinfo.h */
diff --git a/sysdeps/csky/stackinfo.h b/sysdeps/csky/stackinfo.h
index ef22fa3249..2a08fa8fdf 100644
--- a/sysdeps/csky/stackinfo.h
+++ b/sysdeps/csky/stackinfo.h
@@ -24,6 +24,4 @@
/* On C-SKY the stack grows down. */
#define _STACK_GROWS_DOWN 1
-#define DEFAULT_STACK_PERMS (PF_R|PF_W)
-
#endif /* stackinfo.h */
diff --git a/sysdeps/generic/stackperms.h b/sysdeps/generic/stackperms.h
new file mode 100644
index 0000000000..59f47283db
--- /dev/null
+++ b/sysdeps/generic/stackperms.h
@@ -0,0 +1,25 @@
+/* Define DEFAULT_STACK_PERMS which is the default stack permissions
+ when PT_GNU_STACK is absent. Generic version.
+ Copyright (C) 2024 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <https://www.gnu.org/licenses/>. */
+
+#ifndef _STACKPERMS_H
+#define _STACKPERMS_H 1
+
+#define DEFAULT_STACK_PERMS (PF_R|PF_W)
+
+#endif
diff --git a/sysdeps/hppa/stackinfo.h b/sysdeps/hppa/stackinfo.h
index 6298a9eab7..157dc4dae8 100644
--- a/sysdeps/hppa/stackinfo.h
+++ b/sysdeps/hppa/stackinfo.h
@@ -23,10 +23,6 @@
#include <elf.h>
-/* Default to an executable stack. PF_X can be overridden if PT_GNU_STACK is
- * present, but it is presumed absent. */
-#define DEFAULT_STACK_PERMS (PF_R|PF_W|PF_X)
-
/* On PA the stack grows up. */
#define _STACK_GROWS_UP 1
diff --git a/sysdeps/i386/stackinfo.h b/sysdeps/i386/stackinfo.h
index d44c4894f5..979cfbc383 100644
--- a/sysdeps/i386/stackinfo.h
+++ b/sysdeps/i386/stackinfo.h
@@ -26,10 +26,6 @@
/* On x86 the stack grows down. */
#define _STACK_GROWS_DOWN 1
-/* Default to an executable stack. PF_X can be overridden if PT_GNU_STACK is
- * present, but it is presumed absent. */
-#define DEFAULT_STACK_PERMS (PF_R|PF_W|PF_X)
-
/* Access to the stack pointer. The macros are used in alloca_account
for which they need to act as barriers as well, hence the additional
(unnecessary) parameters. */
diff --git a/sysdeps/loongarch/stackinfo.h b/sysdeps/loongarch/stackinfo.h
index 6ee50552b7..3447377096 100644
--- a/sysdeps/loongarch/stackinfo.h
+++ b/sysdeps/loongarch/stackinfo.h
@@ -27,7 +27,4 @@
/* On LoongArch the stack grows down. */
#define _STACK_GROWS_DOWN 1
-/* Default to a non-executable stack. */
-#define DEFAULT_STACK_PERMS (PF_R | PF_W)
-
#endif /* stackinfo.h */
diff --git a/sysdeps/m68k/stackinfo.h b/sysdeps/m68k/stackinfo.h
index 7fdb7c04c2..bc7936c531 100644
--- a/sysdeps/m68k/stackinfo.h
+++ b/sysdeps/m68k/stackinfo.h
@@ -26,10 +26,6 @@
/* On m68k the stack grows down. */
#define _STACK_GROWS_DOWN 1
-/* Default to an executable stack. PF_X can be overridden if PT_GNU_STACK
- is present, but it is presumed absent. */
-#define DEFAULT_STACK_PERMS (PF_R|PF_W|PF_X)
-
/* Access to the stack pointer. */
#define stackinfo_get_sp() \
({ void *p__; asm volatile ("move.l %%sp, %0" : "=r" (p__)); p__; })
diff --git a/sysdeps/microblaze/stackinfo.h b/sysdeps/microblaze/stackinfo.h
index d0b3f16d2f..83f0ac7c7d 100644
--- a/sysdeps/microblaze/stackinfo.h
+++ b/sysdeps/microblaze/stackinfo.h
@@ -27,8 +27,4 @@
/* On MicroBlaze the stack grows down. */
# define _STACK_GROWS_DOWN 1
-/* Default to an executable stack. PF_X can be overridden if PT_GNU_STACK is
- * present, but it is presumed absent. */
-# define DEFAULT_STACK_PERMS (PF_R|PF_W|PF_X)
-
#endif /* stackinfo.h. */
diff --git a/sysdeps/mips/stackinfo.h b/sysdeps/mips/stackinfo.h
index 10f80bf495..bb339d5c69 100644
--- a/sysdeps/mips/stackinfo.h
+++ b/sysdeps/mips/stackinfo.h
@@ -26,8 +26,4 @@
/* On MIPS the stack grows down. */
#define _STACK_GROWS_DOWN 1
-/* Default to an executable stack. PF_X can be overridden if PT_GNU_STACK is
- * present, but it is presumed absent. */
-#define DEFAULT_STACK_PERMS (PF_R|PF_W|PF_X)
-
#endif /* stackinfo.h */
diff --git a/sysdeps/nios2/stackinfo.h b/sysdeps/nios2/stackinfo.h
index e67d53ee87..c302bd4607 100644
--- a/sysdeps/nios2/stackinfo.h
+++ b/sysdeps/nios2/stackinfo.h
@@ -27,7 +27,4 @@
/* On Nios II the stack grows down. */
#define _STACK_GROWS_DOWN 1
-/* Default to a non-executable stack. */
-#define DEFAULT_STACK_PERMS (PF_R|PF_W)
-
#endif /* stackinfo.h */
diff --git a/sysdeps/or1k/stackinfo.h b/sysdeps/or1k/stackinfo.h
index 6d37e0e2f0..76f94b28ad 100644
--- a/sysdeps/or1k/stackinfo.h
+++ b/sysdeps/or1k/stackinfo.h
@@ -27,8 +27,4 @@
/* On or1k the stack grows down. */
#define _STACK_GROWS_DOWN 1
-/* Default to an executable stack. PF_X can be overridden if PT_GNU_STACK is
- present, but it is presumed absent. */
-#define DEFAULT_STACK_PERMS (PF_R | PF_W | PF_X)
-
#endif /* stackinfo.h */
diff --git a/sysdeps/powerpc/stackinfo.h b/sysdeps/powerpc/stackinfo.h
index 410689bc27..52aafb52ba 100644
--- a/sysdeps/powerpc/stackinfo.h
+++ b/sysdeps/powerpc/stackinfo.h
@@ -26,13 +26,4 @@
/* On PPC the stack grows down. */
#define _STACK_GROWS_DOWN 1
-#if __WORDSIZE == 64
-/* PPC64 doesn't need an executable stack and doesn't need PT_GNU_STACK
- * to make the stack nonexecutable. */
-# define DEFAULT_STACK_PERMS (PF_R|PF_W)
-#else
-/* PF_X can be overridden if PT_GNU_STACK is present but is presumed absent. */
-# define DEFAULT_STACK_PERMS (PF_R|PF_W|PF_X)
-#endif
-
#endif /* stackinfo.h */
diff --git a/sysdeps/riscv/stackinfo.h b/sysdeps/riscv/stackinfo.h
index a786d4f9b0..cc28f7080c 100644
--- a/sysdeps/riscv/stackinfo.h
+++ b/sysdeps/riscv/stackinfo.h
@@ -27,7 +27,4 @@
/* On RISC-V the stack grows down. */
#define _STACK_GROWS_DOWN 1
-/* Default to a non-executable stack. */
-#define DEFAULT_STACK_PERMS (PF_R | PF_W)
-
#endif /* stackinfo.h */
diff --git a/sysdeps/s390/stackinfo.h b/sysdeps/s390/stackinfo.h
index c89371c35f..ac5b668bac 100644
--- a/sysdeps/s390/stackinfo.h
+++ b/sysdeps/s390/stackinfo.h
@@ -26,8 +26,4 @@
/* On s390 the stack grows down. */
#define _STACK_GROWS_DOWN 1
-/* Default to an executable stack. PF_X can be overridden if PT_GNU_STACK is
- * present, but it is presumed absent. */
-#define DEFAULT_STACK_PERMS (PF_R|PF_W|PF_X)
-
#endif /* stackinfo.h */
diff --git a/sysdeps/sh/stackinfo.h b/sysdeps/sh/stackinfo.h
index f5caac3f1d..de95e8b744 100644
--- a/sysdeps/sh/stackinfo.h
+++ b/sysdeps/sh/stackinfo.h
@@ -26,8 +26,4 @@
/* On SH the stack grows down. */
#define _STACK_GROWS_DOWN 1
-/* Default to an executable stack. PF_X can be overridden if PT_GNU_STACK is
- * present, but it is presumed absent. */
-#define DEFAULT_STACK_PERMS (PF_R|PF_W|PF_X)
-
#endif /* stackinfo.h */
diff --git a/sysdeps/sparc/stackinfo.h b/sysdeps/sparc/stackinfo.h
index f1e706bc58..ce6210ce42 100644
--- a/sysdeps/sparc/stackinfo.h
+++ b/sysdeps/sparc/stackinfo.h
@@ -26,8 +26,4 @@
/* On sparc the stack grows down. */
#define _STACK_GROWS_DOWN 1
-/* Default to an executable stack. PF_X can be overridden if PT_GNU_STACK is
- * present, but it is presumed absent. */
-#define DEFAULT_STACK_PERMS (PF_R|PF_W|PF_X)
-
#endif /* stackinfo.h */
diff --git a/sysdeps/x86_64/stackinfo.h b/sysdeps/x86_64/stackinfo.h
index 2cb24a74bb..35b4c9cd6c 100644
--- a/sysdeps/x86_64/stackinfo.h
+++ b/sysdeps/x86_64/stackinfo.h
@@ -32,10 +32,6 @@
/* On x86_64 the stack grows down. */
#define _STACK_GROWS_DOWN 1
-/* Default to an executable stack. PF_X can be overridden if PT_GNU_STACK is
- * present, but it is presumed absent. */
-#define DEFAULT_STACK_PERMS (PF_R|PF_W|PF_X)
-
/* Access to the stack pointer. The macros are used in alloca_account
for which they need to act as barriers as well, hence the additional
(unnecessary) parameters. */
--
2.45.2
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