diff options
| author | Joerg Roedel <jroedel@suse.de> | 2020-09-07 15:15:49 +0200 |
|---|---|---|
| committer | Borislav Petkov <bp@suse.de> | 2020-09-09 11:33:19 +0200 |
| commit | 5e3427a7bc432ed2e5de394ac30f160cc6c37a1f (patch) | |
| tree | 41b1afdd929ab485a2fbc82f73ac7c2e8af4006b /arch/x86 | |
| parent | d3529bb73f76d0ec8aafaca505226fa0971c1dc9 (diff) | |
x86/sev-es: Handle instruction fetches from user-space
When a #VC exception is triggered by user-space, the instruction decoder
needs to read the instruction bytes from user addresses. Enhance
vc_decode_insn() to safely fetch kernel and user instructions.
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20200907131613.12703-49-joro@8bytes.org
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/kernel/sev-es.c | 31 |
1 files changed, 22 insertions, 9 deletions
diff --git a/arch/x86/kernel/sev-es.c b/arch/x86/kernel/sev-es.c index b10a62a78c07..6c30dbc1144a 100644 --- a/arch/x86/kernel/sev-es.c +++ b/arch/x86/kernel/sev-es.c @@ -232,17 +232,30 @@ static enum es_result vc_decode_insn(struct es_em_ctxt *ctxt) enum es_result ret; int res; - res = vc_fetch_insn_kernel(ctxt, buffer); - if (unlikely(res == -EFAULT)) { - ctxt->fi.vector = X86_TRAP_PF; - ctxt->fi.error_code = 0; - ctxt->fi.cr2 = ctxt->regs->ip; - return ES_EXCEPTION; + if (user_mode(ctxt->regs)) { + res = insn_fetch_from_user(ctxt->regs, buffer); + if (!res) { + ctxt->fi.vector = X86_TRAP_PF; + ctxt->fi.error_code = X86_PF_INSTR | X86_PF_USER; + ctxt->fi.cr2 = ctxt->regs->ip; + return ES_EXCEPTION; + } + + if (!insn_decode(&ctxt->insn, ctxt->regs, buffer, res)) + return ES_DECODE_FAILED; + } else { + res = vc_fetch_insn_kernel(ctxt, buffer); + if (res) { + ctxt->fi.vector = X86_TRAP_PF; + ctxt->fi.error_code = X86_PF_INSTR; + ctxt->fi.cr2 = ctxt->regs->ip; + return ES_EXCEPTION; + } + + insn_init(&ctxt->insn, buffer, MAX_INSN_SIZE - res, 1); + insn_get_length(&ctxt->insn); } - insn_init(&ctxt->insn, buffer, MAX_INSN_SIZE - res, 1); - insn_get_length(&ctxt->insn); - ret = ctxt->insn.immediate.got ? ES_OK : ES_DECODE_FAILED; return ret; |