diff --git a/sysdeps/aarch64/Makefile b/sysdeps/aarch64/Makefile index 141d7d9cc2..74479604f2 100644 --- a/sysdeps/aarch64/Makefile +++ b/sysdeps/aarch64/Makefile @@ -9,7 +9,9 @@ LDFLAGS-rtld += -Wl,-z,force-bti,--fatal-warnings endif ifeq ($(subdir),elf) -sysdep-dl-routines += dl-bti +sysdep-dl-routines += \ + dl-bti \ + dl-gcs tests += tst-audit26 \ tst-audit27 @@ -35,7 +37,9 @@ endif ifeq ($(subdir),elf) sysdep-rtld-routines += dl-start sysdep-dl-routines += tlsdesc dl-tlsdesc -gen-as-const-headers += dl-link.sym +gen-as-const-headers += \ + dl-link.sym \ + rtld-global-offsets.sym tests-internal += tst-ifunc-arg-1 tst-ifunc-arg-2 diff --git a/sysdeps/aarch64/dl-gcs.c b/sysdeps/aarch64/dl-gcs.c new file mode 100644 index 0000000000..870336f2bb --- /dev/null +++ b/sysdeps/aarch64/dl-gcs.c @@ -0,0 +1,25 @@ +/* AArch64 GCS functions. + Copyright (C) 2024-2025 Free Software Foundation, Inc. + + 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 + . */ + +#include + +/* Used to report error when prctl system call to enabled GCS fails. */ + +void _dl_gcs_enable_failed (int code) +{ + _dl_fatal_printf ("failed to enable GCS: %d\n", -code); +} diff --git a/sysdeps/aarch64/dl-start.S b/sysdeps/aarch64/dl-start.S index 3b8eff0acd..a249fda21c 100644 --- a/sysdeps/aarch64/dl-start.S +++ b/sysdeps/aarch64/dl-start.S @@ -18,6 +18,7 @@ . */ #include +#include ENTRY (_start) /* Create an initial frame with 0 LR and FP */ @@ -25,11 +26,33 @@ ENTRY (_start) mov x29, #0 mov x30, #0 + /* Load and relocate all library dependencies. */ mov x0, sp PTR_ARG (0) bl _dl_start /* Returns user entry point in x0. */ mov PTR_REG (21), PTR_REG (0) + + /* Use GL(dl_aarch64_gcs) to set the shadow stack status. */ + adrp x16, _rtld_local + add PTR_REG (16), PTR_REG (16), :lo12:_rtld_local + ldr x1, [x16, GL_DL_AARCH64_GCS_OFFSET] + cbz x1, L(skip_gcs_enable) + + /* Enable GCS before user code runs. Note that IFUNC resolvers and + LD_AUDIT hooks may run before, but should not create threads. */ +#define PR_SET_SHADOW_STACK_STATUS 75 +#define PR_SHADOW_STACK_ENABLE (1UL << 0) + mov x0, PR_SET_SHADOW_STACK_STATUS + mov x1, PR_SHADOW_STACK_ENABLE + mov x2, 0 + mov x3, 0 + mov x4, 0 + mov x8, #SYS_ify(prctl) + svc 0x0 + cbnz w0, L(failed_gcs_enable) +L(skip_gcs_enable): + .globl _dl_start_user .type _dl_start_user, %function _dl_start_user: @@ -40,14 +63,17 @@ _dl_start_user: /* Compute envp. */ add PTR_REG (3), PTR_REG (2), PTR_REG (1), lsl PTR_LOG_SIZE add PTR_REG (3), PTR_REG (3), PTR_SIZE - adrp x16, _rtld_local - add PTR_REG (16), PTR_REG (16), :lo12:_rtld_local + /* Run the init functions of the loaded modules. */ ldr PTR_REG (0), [x16] bl _dl_init /* Load the finalizer function. */ adrp x0, _dl_fini add PTR_REG (0), PTR_REG (0), :lo12:_dl_fini /* Jump to the user's entry point. */ - mov x16, x21 - br x16 + mov x16, x21 + br x16 + +L(failed_gcs_enable): + b _dl_gcs_enable_failed + END (_start) diff --git a/sysdeps/aarch64/rtld-global-offsets.sym b/sysdeps/aarch64/rtld-global-offsets.sym index 23cdaf7d9e..6c0690bb95 100644 --- a/sysdeps/aarch64/rtld-global-offsets.sym +++ b/sysdeps/aarch64/rtld-global-offsets.sym @@ -3,8 +3,13 @@ #include #define GLRO_offsetof(name) offsetof (struct rtld_global_ro, _##name) +#define GL_offsetof(name) offsetof (struct rtld_global, _##name) -- Offsets of _rtld_global_ro in libc.so GLRO_DL_HWCAP_OFFSET GLRO_offsetof (dl_hwcap) GLRO_DL_HWCAP2_OFFSET GLRO_offsetof (dl_hwcap2) + +-- Offsets of _rtld_global in libc.so + +GL_DL_AARCH64_GCS_OFFSET GL_offsetof (dl_aarch64_gcs)