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| author | Szabolcs Nagy <szabolcs.nagy@arm.com> | 2023-07-14 15:49:11 +0100 |
|---|---|---|
| committer | Szabolcs Nagy <szabolcs.nagy@arm.com> | 2024-07-08 09:41:44 +0100 |
| commit | 01204afc0d82e3fc47a65a3f6330c09d8e7459ee (patch) | |
| tree | bdeffb5b064a121d9e9641f24d4996ccabeac495 | |
| parent | a289e5dea083955eefbea82062d567a5c8026388 (diff) | |
| download | glibc-01204afc0d82e3fc47a65a3f6330c09d8e7459ee.zip glibc-01204afc0d82e3fc47a65a3f6330c09d8e7459ee.tar.gz glibc-01204afc0d82e3fc47a65a3f6330c09d8e7459ee.tar.bz2 | |
aarch64: Enable GCS in dynamic linked exe
Use the dynamic linker start code to enable GCS in the dynamic linked
case after _dl_start returns and before _dl_start_user which marks
the point after which user code may run.
Like in the static linked case this ensures that GCS is enabled on a
top level stack frame.
| -rw-r--r-- | sysdeps/aarch64/Makefile | 4 | ||||
| -rw-r--r-- | sysdeps/aarch64/dl-start.S | 23 | ||||
| -rw-r--r-- | sysdeps/aarch64/rtld-global-offsets.sym | 5 |
3 files changed, 29 insertions, 3 deletions
diff --git a/sysdeps/aarch64/Makefile b/sysdeps/aarch64/Makefile index 141d7d9..ca8b96f 100644 --- a/sysdeps/aarch64/Makefile +++ b/sysdeps/aarch64/Makefile @@ -35,7 +35,9 @@ 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-start.S b/sysdeps/aarch64/dl-start.S index d645484..271bd5b 100644 --- a/sysdeps/aarch64/dl-start.S +++ b/sysdeps/aarch64/dl-start.S @@ -18,6 +18,7 @@ <https://www.gnu.org/licenses/>. */ #include <sysdep.h> +#include <rtld-global-offsets.h> ENTRY (_start) /* Create an initial frame with 0 LR and FP */ @@ -25,11 +26,30 @@ 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 72 + mov x0, PR_SET_SHADOW_STACK_STATUS + mov x2, 0 + mov x3, 0 + mov x4, 0 + mov x8, #SYS_ify(prctl) + svc 0x0 +L(skip_gcs_enable): + .globl _dl_start_user .type _dl_start_user, %function _dl_start_user: @@ -40,8 +60,7 @@ _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. */ diff --git a/sysdeps/aarch64/rtld-global-offsets.sym b/sysdeps/aarch64/rtld-global-offsets.sym index 23cdaf7..6c0690b 100644 --- a/sysdeps/aarch64/rtld-global-offsets.sym +++ b/sysdeps/aarch64/rtld-global-offsets.sym @@ -3,8 +3,13 @@ #include <ldsodefs.h> #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) |