From 41eed6e1878d93753ff82913d4577616c4778fa7 Mon Sep 17 00:00:00 2001 From: Indu Bhagat Date: Thu, 22 Dec 2022 09:57:02 -0800 Subject: [PATCH] sframe.h: add support for .cfi_b_key_frame ARM 8.3 provides five separate keys that can be used to authenticate pointers. There are two key for executable (instruction) pointers. The enum pointer_auth_key in gas/config/tc-aarch64.h currently holds two keys: enum pointer_auth_key { AARCH64_PAUTH_KEY_A, AARCH64_PAUTH_KEY_B }; Analogous to the above, in SFrame format V1, a bit is reserved in the SFrame FDE to indicate which key is used for signing the frame's return addresses: - SFRAME_AARCH64_PAUTH_KEY_A has a value of 0 - SFRAME_AARCH64_PAUTH_KEY_B has a value of 1 Note that the information in this bit will always be used along with the mangled_ra_p bit, the latter indicates whether the return addresses are mangled/contain PAC auth bits. include/ChangeLog: * sframe.h (SFRAME_AARCH64_PAUTH_KEY_A): New definition. (SFRAME_AARCH64_PAUTH_KEY_B): Likewise. (SFRAME_V1_FUNC_INFO): Adjust to accommodate pauth_key. (SFRAME_V1_FUNC_PAUTH_KEY): New macro. (SFRAME_V1_FUNC_INFO_UPDATE_PAUTH_KEY): Likewise. --- include/sframe.h | 25 +++++++++++++++++++------ 1 file changed, 19 insertions(+), 6 deletions(-) diff --git a/include/sframe.h b/include/sframe.h index b2bd41a724e..77071c99d90 100644 --- a/include/sframe.h +++ b/include/sframe.h @@ -165,6 +165,10 @@ typedef struct sframe_header #define SFRAME_V1_HDR_SIZE(sframe_hdr) \ ((sizeof (sframe_header) + (sframe_hdr).sfh_auxhdr_len)) +/* Two possible keys for executable (instruction) pointers signing. */ +#define SFRAME_AARCH64_PAUTH_KEY_A 0 /* Key A. */ +#define SFRAME_AARCH64_PAUTH_KEY_B 1 /* Key B. */ + typedef struct sframe_func_desc_entry { /* Function start address. Encoded as a signed offset, relative to the @@ -181,21 +185,30 @@ typedef struct sframe_func_desc_entry function. - 4-bits: Identify the FRE type used for the function. - 1-bit: Identify the FDE type of the function - mask or inc. - - 3-bits: Unused. - -------------------------------------------- - | Unused | FDE type | FRE type | - -------------------------------------------- - 8 5 4 0 */ + - 1-bit: PAC authorization A/B key (aarch64). + - 2-bits: Unused. + ------------------------------------------------------------------------ + | Unused | PAC auth A/B key (aarch64) | FDE type | FRE type | + | | Unused (amd64) | | | + ------------------------------------------------------------------------ + 8 6 5 4 0 */ uint8_t sfde_func_info; } ATTRIBUTE_PACKED sframe_func_desc_entry; /* Macros to compose and decompose function info in FDE. */ +/* Note: Set PAC auth key to SFRAME_AARCH64_PAUTH_KEY_A by default. */ #define SFRAME_V1_FUNC_INFO(fde_type, fre_enc_type) \ - ((((fde_type) & 0x1) << 4) | ((fre_enc_type) & 0xf)) + (((SFRAME_AARCH64_PAUTH_KEY_A & 0x1) << 5) | \ + (((fde_type) & 0x1) << 4) | ((fre_enc_type) & 0xf)) #define SFRAME_V1_FUNC_FRE_TYPE(data) ((data) & 0xf) #define SFRAME_V1_FUNC_FDE_TYPE(data) (((data) >> 4) & 0x1) +#define SFRAME_V1_FUNC_PAUTH_KEY(data) (((data) >> 5) & 0x1) + +/* Set the pauth key as indicated. */ +#define SFRAME_V1_FUNC_INFO_UPDATE_PAUTH_KEY(pauth_key, fde_info) \ + ((((pauth_key) & 0x1) << 5) | ((fde_info) & 0xdf)) /* Size of stack frame offsets in an SFrame Frame Row Entry. A single SFrame FRE has all offsets of the same size. Offset size may vary -- 2.30.2