diff options
| author | Joerg Roedel <jroedel@suse.de> | 2023-10-16 14:42:50 +0200 |
|---|---|---|
| committer | Borislav Petkov (AMD) <bp@alien8.de> | 2023-10-17 10:58:16 +0200 |
| commit | 63e44bc52047f182601e7817da969a105aa1f721 (patch) | |
| tree | 3a627e7e557da4e8273458595a8483fab82b2fa4 /arch | |
| parent | x86/sev: Check IOBM for IOIO exceptions from user-space (diff) | |
| download | linux-63e44bc52047f182601e7817da969a105aa1f721.tar.xz linux-63e44bc52047f182601e7817da969a105aa1f721.zip | |
x86/sev: Check for user-space IOIO pointing to kernel space
Check the memory operand of INS/OUTS before emulating the instruction.
The #VC exception can get raised from user-space, but the memory operand
can be manipulated to access kernel memory before the emulation actually
begins and after the exception handler has run.
[ bp: Massage commit message. ]
Fixes: 597cfe48212a ("x86/boot/compressed/64: Setup a GHCB-based VC Exception handler")
Reported-by: Tom Dohrmann <erbse.13@gmx.de>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Cc: <stable@kernel.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/boot/compressed/sev.c | 5 | ||||
| -rw-r--r-- | arch/x86/kernel/sev-shared.c | 31 |
2 files changed, 34 insertions, 2 deletions
diff --git a/arch/x86/boot/compressed/sev.c b/arch/x86/boot/compressed/sev.c index afd91041ec3e..80d76aea1f7b 100644 --- a/arch/x86/boot/compressed/sev.c +++ b/arch/x86/boot/compressed/sev.c @@ -108,6 +108,11 @@ static enum es_result vc_ioio_check(struct es_em_ctxt *ctxt, u16 port, size_t si return ES_OK; } +static bool fault_in_kernel_space(unsigned long address) +{ + return false; +} + #undef __init #define __init diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c index bcd77c48be0a..4d729686f992 100644 --- a/arch/x86/kernel/sev-shared.c +++ b/arch/x86/kernel/sev-shared.c @@ -592,6 +592,23 @@ fail: sev_es_terminate(SEV_TERM_SET_GEN, GHCB_SEV_ES_GEN_REQ); } +static enum es_result vc_insn_string_check(struct es_em_ctxt *ctxt, + unsigned long address, + bool write) +{ + if (user_mode(ctxt->regs) && fault_in_kernel_space(address)) { + ctxt->fi.vector = X86_TRAP_PF; + ctxt->fi.error_code = X86_PF_USER; + ctxt->fi.cr2 = address; + if (write) + ctxt->fi.error_code |= X86_PF_WRITE; + + return ES_EXCEPTION; + } + + return ES_OK; +} + static enum es_result vc_insn_string_read(struct es_em_ctxt *ctxt, void *src, char *buf, unsigned int data_size, @@ -599,7 +616,12 @@ static enum es_result vc_insn_string_read(struct es_em_ctxt *ctxt, bool backwards) { int i, b = backwards ? -1 : 1; - enum es_result ret = ES_OK; + unsigned long address = (unsigned long)src; + enum es_result ret; + + ret = vc_insn_string_check(ctxt, address, false); + if (ret != ES_OK) + return ret; for (i = 0; i < count; i++) { void *s = src + (i * data_size * b); @@ -620,7 +642,12 @@ static enum es_result vc_insn_string_write(struct es_em_ctxt *ctxt, bool backwards) { int i, s = backwards ? -1 : 1; - enum es_result ret = ES_OK; + unsigned long address = (unsigned long)dst; + enum es_result ret; + + ret = vc_insn_string_check(ctxt, address, true); + if (ret != ES_OK) + return ret; for (i = 0; i < count; i++) { void *d = dst + (i * data_size * s); |