This patch implements the specification found here:
http://www.trustedcomputinggroup.org/resources/tcg_physical_presence_interfa...
It adds the necessary BIOS code so that for example an administrator can send messages from the OS to the BIOS for the BIOS to change the state of the TPM upon reboot. With the help of this interface, an administrator does not have to manually interact with the BIOS.
As an example, on Linux the root use can send an opcode to the BIOS through the TPM's sysfs entries following the opcodes listed in table 2 of the above specs. To for example disable and deactivate the TPM, the root user would send opcode '7' to the BIOS:
#> cd /sys/devices/pnp0/00:0?/ppi
#> echo 7 > request
#> reboot
This patch allocates an 'anchor' in the f-segment identifiable by the signature 'TCG_MAGIC'. It also allocates a chunk of memory in the high memory region and points to it from the anchor. The memory in the high memory region may have been initialized with the signature 'TCG_MAGIC' on a previous boot and if this signature is found, the opcode (sent from the OS) is looked at and acted upon by the BIOS.
The implementation requires an ACPI _DSM method to be implemented for the TPM's SSDT. The code in the _DSM will look for the anchor in the f-segment and write the administrator's opcode into the high memory area. The _DSM method is invoked when the root user interacts with the entries shown in the above ppi sysfs directory. The patch implementing the _DSM will be posted independently.
This patch supports opcodes 1-11, 14, 21, and 22.
Signed-off-by: Stefan Berger stefanb@linux.vnet.ibm.com --- src/post.c | 3 + src/tcgbios.c | 584 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ src/tcgbios.h | 54 ++++++ 3 files changed, 641 insertions(+)
diff --git a/src/post.c b/src/post.c index e273c18..4c944c8 100644 --- a/src/post.c +++ b/src/post.c @@ -219,6 +219,7 @@ maininit(void)
// Setup platform devices. platform_hardware_setup(); + tpm_ppi_init();
// Start hardware initialization (if threads allowed during optionroms) if (threads_during_optionroms()) @@ -240,6 +241,8 @@ maininit(void) // Run option roms optionrom_setup();
+ // Process user-requested TPM state change + tpm_ppi_process(); // Allow user to modify overall boot order. interactive_bootmenu(); wait_threads(); diff --git a/src/tcgbios.c b/src/tcgbios.c index 3f31231..1d93d77 100644 --- a/src/tcgbios.c +++ b/src/tcgbios.c @@ -24,6 +24,7 @@ #include "bregs.h" // struct bregs #include "sha1.h" // sha1 #include "std/smbios.h" +#include "malloc.h" // malloc_*
static const u8 Startup_ST_CLEAR[2] = { 0x00, TPM_ST_CLEAR }; @@ -42,6 +43,11 @@ static const u8 GetCapability_Permanent_Flags[12] = { 0x00, 0x00, 0x01, 0x08 };
+static const u8 GetCapability_STClear_Flags[12] = { + 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00, 0x04, + 0x00, 0x00, 0x01, 0x09 +}; + static const u8 GetCapability_OwnerAuth[12] = { 0x00, 0x00, 0x00, 0x05, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x01, 0x11 @@ -89,6 +95,10 @@ static tpm_state_t tpm_state = { .tpm_driver_to_use = TPM_INVALID_DRIVER, };
+typedef struct { + u8 op; +} tpm_bios_cfg_t; +
/******************************************************** Extensions for TCG-enabled BIOS @@ -1438,6 +1448,521 @@ tpm_ipl(enum ipltype bootcd, const u8 *addr, u32 length) return rc; }
+static u32 +read_stclear_flags(char *buf, int buf_len) +{ + u32 rc; + u32 returnCode; + struct tpm_res_getcap_stclear_flags stcf; + + memset(buf, 0x0, buf_len); + + rc = build_and_send_cmd(0, TPM_ORD_GetCapability, + GetCapability_STClear_Flags, + sizeof(GetCapability_STClear_Flags), + (u8 *)&stcf, + sizeof(struct tpm_res_getcap_stclear_flags), + &returnCode, TPM_DURATION_TYPE_SHORT); + + dprintf(DEBUG_tcg, "TCGBIOS: Return code from TPM_GetCapability() " + "= 0x%08x\n", returnCode); + + if (rc || returnCode) + goto err_exit; + + memcpy(buf, &stcf.stclear_flags, buf_len); + + return 0; + +err_exit: + dprintf(DEBUG_tcg, "TCGBIOS: TPM malfunctioning (line %d).\n", __LINE__); + + tpm_state.tpm_working = 0; + if (rc) + return rc; + return TCG_TCG_COMMAND_ERROR; +} + + +static u32 +assert_physical_presence(int verbose) +{ + u32 rc = 0; + u32 returnCode; + struct tpm_stclear_flags stcf; + + rc = read_stclear_flags((char *)&stcf, sizeof(stcf)); + if (rc) { + dprintf(DEBUG_tcg, + "Error reading STClear flags: 0x%08x\n", rc); + return rc; + } + + if (stcf.flags[STCLEAR_FLAG_IDX_PHYSICAL_PRESENCE]) + /* physical presence already asserted */ + return 0; + + rc = build_and_send_cmd(0, TPM_ORD_PhysicalPresence, + PhysicalPresence_CMD_ENABLE, + sizeof(PhysicalPresence_CMD_ENABLE), + NULL, 10, &returnCode, TPM_DURATION_TYPE_SHORT); + + dprintf(DEBUG_tcg, + "Return code from TSC_PhysicalPresence(CMD_ENABLE) = 0x%08x\n", + returnCode); + + if (rc || returnCode) { + if (verbose) + printf("Error: Could not enable physical presence.\n\n"); + goto err_exit; + } + + rc = build_and_send_cmd(0, TPM_ORD_PhysicalPresence, + PhysicalPresence_PRESENT, + sizeof(PhysicalPresence_PRESENT), + NULL, 10, &returnCode, TPM_DURATION_TYPE_SHORT); + + dprintf(DEBUG_tcg, + "Return code from TSC_PhysicalPresence(PRESENT) = 0x%08x\n", + returnCode); + + if (rc || returnCode) { + if (verbose) + printf("Error: Could not set presence flag.\n\n"); + goto err_exit; + } + + return 0; + +err_exit: + dprintf(DEBUG_tcg, "TCGBIOS: TPM malfunctioning (line %d).\n", __LINE__); + + tpm_state.tpm_working = 0; + if (rc) + return rc; + return TCG_TCG_COMMAND_ERROR; +} + + +static u32 +read_permanent_flags(char *buf, int buf_len) +{ + u32 rc; + u32 returnCode; + struct tpm_res_getcap_perm_flags pf; + + memset(buf, 0x0, buf_len); + + rc = build_and_send_cmd(0, TPM_ORD_GetCapability, + GetCapability_Permanent_Flags, + sizeof(GetCapability_Permanent_Flags), + (u8 *)&pf, + sizeof(struct tpm_res_getcap_perm_flags), + &returnCode, TPM_DURATION_TYPE_SHORT); + + dprintf(DEBUG_tcg, "TCGBIOS: Return code from TPM_GetCapability() " + "= 0x%08x\n", returnCode); + + if (rc || returnCode) + goto err_exit; + + memcpy(buf, &pf.perm_flags, buf_len); + + return 0; + +err_exit: + dprintf(DEBUG_tcg, "TCGBIOS: TPM malfunctioning (line %d).\n", __LINE__); + + tpm_state.tpm_working = 0; + if (rc) + return rc; + return TCG_TCG_COMMAND_ERROR; +} + + +static u32 +read_has_owner(u8 *has_owner) +{ + u32 rc; + u32 returnCode; + struct tpm_res_getcap_ownerauth oauth; + + rc = build_and_send_cmd(0, TPM_ORD_GetCapability, + GetCapability_OwnerAuth, + sizeof(GetCapability_OwnerAuth), + (u8 *)&oauth, + sizeof(struct tpm_res_getcap_ownerauth), + &returnCode, TPM_DURATION_TYPE_SHORT); + + dprintf(DEBUG_tcg, "TCGBIOS: Return code from TPM_GetCapability() " + "= 0x%08x\n", returnCode); + + if (rc || returnCode) + goto err_exit; + + *has_owner = oauth.flag; + + return 0; + +err_exit: + dprintf(DEBUG_tcg,"TCGBIOS: TPM malfunctioning (line %d).\n", __LINE__); + + tpm_state.tpm_working = 0; + if (rc) + return rc; + return TCG_TCG_COMMAND_ERROR; +} + + +static u32 +disable_tpm(int disable, u32 *returnCode, int verbose) +{ + u32 rc; + struct tpm_permanent_flags pf; + + rc = read_permanent_flags((char *)&pf, sizeof(pf)); + if (rc) + return rc; + + if (!!pf.flags[PERM_FLAG_IDX_DISABLE] == !!disable) { + if (verbose) + printf("TPM is already %s.\n,", + disable ? "disabled" : "enabled"); + return 0; + } + + rc = assert_physical_presence(verbose); + if (rc) { + dprintf(DEBUG_tcg, "TCGBIOS: Asserting physical presence failed.\n"); + return rc; + } + + rc = build_and_send_cmd(0, disable ? TPM_ORD_PhysicalDisable + : TPM_ORD_PhysicalEnable, + NULL, 0, NULL, 10, returnCode, + TPM_DURATION_TYPE_SHORT); + dprintf(DEBUG_tcg, "Return code from TPM_Physical%sable = 0x%08x\n", + disable ? "Dis" : "En", *returnCode); + + if (rc || *returnCode) + goto err_exit; + + + return 0; + +err_exit: + dprintf(DEBUG_tcg, "TCGBIOS: %sabling the TPM failed.\n", + disable ? "Dis" : "En"); + dprintf(DEBUG_tcg, "TCGBIOS: TPM malfunctioning (line %d).\n", __LINE__); + + tpm_state.tpm_working = 0; + if (rc) + return rc; + return TCG_TCG_COMMAND_ERROR; +} + + +static u32 +deactivate_tpm(int deactivate, int allow_reset, u32 *returnCode, int verbose) +{ + u32 rc; + struct tpm_permanent_flags pf; + + rc = read_permanent_flags((char *)&pf, sizeof(pf)); + if (rc) + return rc; + + if (!!pf.flags[PERM_FLAG_IDX_DEACTIVATED] == !!deactivate) { + if (verbose) + printf("TPM is already %s.\n", + deactivate ? "deactivated" : "activated"); + return 0; + } + + if (pf.flags[PERM_FLAG_IDX_DISABLE]) { + if (verbose) + printf("TPM must first be enabled.\n"); + return 0; + } + + rc = assert_physical_presence(verbose); + if (rc) { + dprintf(DEBUG_tcg, "TCGBIOS: Asserting physical presence failed.\n"); + return rc; + } + + rc = build_and_send_cmd(0, TPM_ORD_PhysicalSetDeactivated, + deactivate ? CommandFlag_TRUE + : CommandFlag_FALSE, + deactivate ? sizeof(CommandFlag_TRUE) + : sizeof(CommandFlag_FALSE), + NULL, 10, returnCode, TPM_DURATION_TYPE_SHORT); + + dprintf(DEBUG_tcg, + "Return code from PhysicalSetDeactivated(%d) = 0x%08x\n", + deactivate ? 1 : 0, *returnCode); + + if (rc || *returnCode) + goto err_exit; + + if (!deactivate && allow_reset) { + if (verbose) { + printf("Requiring a reboot to activate the TPM.\n"); + + msleep(2000); + } + extern void reset_vector(void) __noreturn; + reset_vector(); + } + + return 0; + +err_exit: + dprintf(DEBUG_tcg, "TCGBIOS: TPM malfunctioning (line %d).\n", __LINE__); + + tpm_state.tpm_working = 0; + if (rc) + return rc; + return TCG_TCG_COMMAND_ERROR; +} + + +static u32 +enable_activate(int allow_reset, u32 *returnCode, int verbose) +{ + u32 rc; + + rc = disable_tpm(0, returnCode, verbose); + if (rc) + return rc; + + rc = deactivate_tpm(0, allow_reset, returnCode, verbose); + + return rc; +} + + +static u32 +force_clear(int enable_activate_before, int enable_activate_after, + u32 *returnCode, int verbose) +{ + u32 rc; + u8 has_owner; + + rc = read_has_owner(&has_owner); + if (rc) + return rc; + if (!has_owner) { + if (verbose) + printf("TPM does not have an owner.\n"); + return 0; + } + + if (enable_activate_before) { + rc = enable_activate(0, returnCode, verbose); + if (rc) { + dprintf(DEBUG_tcg, + "TCGBIOS: Enabling/activating the TPM failed.\n"); + return rc; + } + } + + rc = assert_physical_presence(verbose); + if (rc) { + dprintf(DEBUG_tcg, "TCGBIOS: Asserting physical presence failed.\n"); + return rc; + } + + rc = build_and_send_cmd(0, TPM_ORD_ForceClear, + NULL, 0, NULL, 10, returnCode, + TPM_DURATION_TYPE_SHORT); + + dprintf(DEBUG_tcg, "Return code from TPM_ForceClear() = 0x%08x\n", + *returnCode); + + if (rc || *returnCode) + goto err_exit; + + if (!enable_activate_after) { + if (verbose) + printf("Owner successfully cleared.\n" + "You will need to enable/activate the TPM again.\n\n"); + return 0; + } + + enable_activate(1, returnCode, verbose); + + return 0; + +err_exit: + dprintf(DEBUG_tcg, "TCGBIOS: TPM malfunctioning (line %d).\n", __LINE__); + + tpm_state.tpm_working = 0; + if (rc) + return rc; + return TCG_TCG_COMMAND_ERROR; +} + + +static u32 +set_owner_install(int allow, u32 *returnCode, int verbose) +{ + u32 rc; + u8 has_owner; + struct tpm_permanent_flags pf; + + rc = read_has_owner(&has_owner); + if (rc) + return rc; + if (has_owner) { + if (verbose) + printf("Must first remove owner.\n"); + return 0; + } + + rc = read_permanent_flags((char *)&pf, sizeof(pf)); + if (rc) + return rc; + + if (pf.flags[PERM_FLAG_IDX_DISABLE]) { + if (verbose) + printf("TPM must first be enable.\n"); + return 0; + } + + rc = assert_physical_presence(verbose); + if (rc) { + dprintf(DEBUG_tcg, "TCGBIOS: Asserting physical presence failed.\n"); + return rc; + } + + rc = build_and_send_cmd(0, TPM_ORD_SetOwnerInstall, + (allow) ? CommandFlag_TRUE : + CommandFlag_FALSE, + sizeof(CommandFlag_TRUE), + NULL, 10, returnCode, TPM_DURATION_TYPE_SHORT); + + dprintf(DEBUG_tcg, "Return code from TPM_SetOwnerInstall() = 0x%08x\n", + *returnCode); + + if (rc || *returnCode) + goto err_exit; + + if (verbose) + printf("Installation of owner %s.\n", allow ? "enabled" : "disabled"); + + return 0; + +err_exit: + dprintf(DEBUG_tcg, "TCGBIOS: TPM malfunctioning (line %d).\n", __LINE__); + tpm_state.tpm_working = 0; + if (rc) + return rc; + return TCG_TCG_COMMAND_ERROR; +} + + +static u32 +tpm_process_cfg(const tpm_bios_cfg_t *cfg, int verbose, + u32 *returnCode, u8 *next_step) +{ + u32 rc = 0; + + switch (cfg->op) { + case 0: /* no-op */ + break; + + case 1: + rc = disable_tpm(0, returnCode, verbose); + break; + + case 2: + rc = disable_tpm(1, returnCode, verbose); + break; + + case 3: + rc = deactivate_tpm(0, 1, returnCode, verbose); + break; + + case 4: + rc = deactivate_tpm(1, 1, returnCode, verbose); + break; + + case 5: + rc = force_clear(1, 0, returnCode, verbose); + break; + + case 6: + rc = enable_activate(1, returnCode, verbose); + break; + + case 7: + rc = deactivate_tpm(1, 1, returnCode, verbose); + if (!rc) + rc = disable_tpm(1, returnCode, verbose); + break; + + case 8: + rc = set_owner_install(1, returnCode, verbose); + break; + + case 9: + rc = set_owner_install(0, returnCode, verbose); + break; + + case 10: + *next_step = 8; + rc = enable_activate(1, returnCode, verbose); + /* no reboot happened */ + if (!rc) + rc = set_owner_install(1, returnCode, verbose); + break; + + case 11: + rc = set_owner_install(0, returnCode, verbose); + if (!rc) + rc = deactivate_tpm(1, 0, returnCode, verbose); + if (!rc) + rc = disable_tpm(1, returnCode, verbose); + break; + + case 14: + rc = force_clear(0, 0, returnCode, verbose); + if (!rc) + rc = enable_activate(1, returnCode, verbose); + break; + + case 21: + *next_step = 5; + rc = enable_activate(1, returnCode, verbose); + /* no reboot happened */ + if (!rc) + rc = force_clear(0, 0, returnCode, verbose); + break; + + case 22: + *next_step = 14; + rc = enable_activate(1, returnCode, verbose); + /* no reboot happened */ + if (!rc) + rc = force_clear(0, 0, returnCode, verbose); + *next_step = 0; + if (!rc) + rc = enable_activate(1, returnCode, verbose); + break; + + default: + break; + } + + if (rc) + printf("Op %d: An error occurred: 0x%x\n", cfg->op, rc); + + /* no reboot, no next step */ + *next_step = 0; + + return rc; +}
u32 tpm_add_bootdevice_ipl(u32 bootcd, u32 bootdrv, @@ -1484,3 +2009,62 @@ err_exit: return rc; return TCG_TCG_COMMAND_ERROR; } + +static int tpm_ppi_found_high = 0; +static struct tpm_ppi *tp; + +void +tpm_ppi_init(void) +{ + struct tpm_ppi_anchor *tpa = malloc_fseg(sizeof(*tpa)); + tp = malloc_high(sizeof(*tp)); + + dprintf(DEBUG_tcg, "Allocated TPM PPI structure at 0x%x\n", (int)tp); + + tpa->sign1 = TCG_MAGIC; + tpa->ptr = tp; + tpa->sign2 = TCG_MAGIC; + + if (tp->sign1 != TCG_MAGIC || tp->sign2 != TCG_MAGIC) { + tp->sign1 = TCG_MAGIC; + tp->sign2 = TCG_MAGIC; + /* set number of bytes that ACPI can read/write */ + tp->size = sizeof(tp->opcode) + sizeof(tp->failure) + + sizeof(tp->recent_opcode) + sizeof(tp->response); + tp->opcode = 0; + tp->recent_opcode = 0; + tp->failure = 0; + tpm_ppi_found_high = 0; + } else { + tpm_ppi_found_high = 1; + } +} + +void +tpm_ppi_process(void) +{ + tpm_bios_cfg_t cfg; + + if (tp) { + cfg.op = tp->opcode; + if (!cfg.op) { + /* intermediate step after a reboot? */ + cfg.op = tp->next_step; + } else { + /* last full opcode */ + tp->recent_opcode = cfg.op; + } + if (cfg.op) { + printf("Processing TPM PPI opcode %d\n", cfg.op); + tp->failure = (tpm_process_cfg(&cfg, 0, &tp->response, + &tp->next_step) != 0); + } + } +} + +void +tpm_ppi_dump(void) +{ + printf("tpm_ppi_found_high = %d\n", tpm_ppi_found_high); + printf("tp = %lx\n", (long)tp); +} diff --git a/src/tcgbios.h b/src/tcgbios.h index 7cf4364..bf5b19b 100644 --- a/src/tcgbios.h +++ b/src/tcgbios.h @@ -328,6 +328,36 @@ struct tpm_res_getcap_perm_flags { } PACKED;
+struct tpm_req_getcap_stclear_flags { + TPM_REQ_HEADER + u32 capArea; + u32 subCapSize; + u32 subCap; +} PACKED; + + +struct tpm_stclear_flags { + u16 tag; + u8 flags[5]; +} PACKED; + + +enum stclearFlagsIndex { + STCLEAR_FLAG_IDX_DEACTIVATED = 0, + STCLEAR_FLAG_IDX_DISABLE_FORCE_CLEAR, + STCLEAR_FLAG_IDX_PHYSICAL_PRESENCE, + STCLEAR_FLAG_IDX_PHYSICAL_PRESENCE_LOCK, + STCLEAR_FLAG_IDX_GLOBAL_LOCK, +}; + + +struct tpm_res_getcap_stclear_flags { + TPM_RSP_HEADER + u32 size; + struct tpm_stclear_flags stclear_flags; +} PACKED; + + struct tpm_res_getcap_ownerauth { TPM_RSP_HEADER u32 size; @@ -378,6 +408,30 @@ enum ipltype { IPL_EL_TORITO_2 };
+/* + * physical presence interface + */ + +struct tpm_ppi { + u32 sign1; + u16 size; // number of subsequent bytes for ACPI to access + u8 opcode; // set by ACPI + u8 failure; // set by BIOS (0 = success) + u8 recent_opcode; // set by BIOS + u32 response; // set by BIOS + u8 next_step; // BIOS only + u32 sign2; +} PACKED; + +struct tpm_ppi_anchor { + u32 sign1; + struct tpm_ppi *ptr; + u32 sign2; +}; + +void tpm_ppi_init(void); +void tpm_ppi_dump(void); +void tpm_ppi_process(void);
struct bregs; void tpm_interrupt_handler32(struct bregs *regs);