/* * Copyright (c) 2015 PLUMgrid, Inc. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ #include #include #include #include #include #include #include #include #include #include #include #include #include "frontend_action_common.h" #include "b_frontend_action.h" #include "bpf_module.h" #include "common.h" #include "loader.h" #include "table_storage.h" #include "arch_helper.h" #include "libbpf.h" namespace ebpf { constexpr int MAX_CALLING_CONV_REGS = 6; const char *calling_conv_regs_x86[] = { "di", "si", "dx", "cx", "r8", "r9" }; const char *calling_conv_regs_ppc[] = {"gpr[3]", "gpr[4]", "gpr[5]", "gpr[6]", "gpr[7]", "gpr[8]"}; const char *calling_conv_regs_s390x[] = {"gprs[2]", "gprs[3]", "gprs[4]", "gprs[5]", "gprs[6]" }; const char *calling_conv_regs_arm64[] = {"regs[0]", "regs[1]", "regs[2]", "regs[3]", "regs[4]", "regs[5]"}; void *get_call_conv_cb(bcc_arch_t arch) { const char **ret; switch(arch) { case BCC_ARCH_PPC: case BCC_ARCH_PPC_LE: ret = calling_conv_regs_ppc; break; case BCC_ARCH_S390X: ret = calling_conv_regs_s390x; break; case BCC_ARCH_ARM64: ret = calling_conv_regs_arm64; break; default: ret = calling_conv_regs_x86; } return (void *)ret; } const char **get_call_conv(void) { const char **ret; ret = (const char **)run_arch_callback(get_call_conv_cb); return ret; } using std::map; using std::move; using std::set; using std::tuple; using std::make_tuple; using std::string; using std::to_string; using std::unique_ptr; using std::vector; using namespace clang; class ProbeChecker : public RecursiveASTVisitor { public: explicit ProbeChecker(Expr *arg, const set> &ptregs, bool track_helpers, bool is_assign) : needs_probe_(false), is_transitive_(false), ptregs_(ptregs), track_helpers_(track_helpers), nb_derefs_(0), is_assign_(is_assign) { if (arg) { TraverseStmt(arg); if (arg->getType()->isPointerType()) is_transitive_ = needs_probe_; } } explicit ProbeChecker(Expr *arg, const set> &ptregs, bool is_transitive) : ProbeChecker(arg, ptregs, is_transitive, false) {} bool VisitCallExpr(CallExpr *E) { needs_probe_ = false; if (is_assign_) { // We're looking for a function that returns an external pointer, // regardless of the number of dereferences. for(auto p : ptregs_) { if (std::get<0>(p) == E->getDirectCallee()) { needs_probe_ = true; nb_derefs_ += std::get<1>(p); return false; } } } else { tuple pt = make_tuple(E->getDirectCallee(), nb_derefs_); if (ptregs_.find(pt) != ptregs_.end()) needs_probe_ = true; } if (!track_helpers_) return false; if (VarDecl *V = dyn_cast(E->getCalleeDecl())) needs_probe_ = V->getName() == "bpf_get_current_task"; return false; } bool VisitMemberExpr(MemberExpr *M) { tuple pt = make_tuple(M->getMemberDecl(), nb_derefs_); if (ptregs_.find(pt) != ptregs_.end()) { needs_probe_ = true; return false; } if (M->isArrow()) { /* In A->b, if A is an external pointer, then A->b should be considered * one too. However, if we're taking the address of A->b * (nb_derefs_ < 0), we should take it into account for the number of * indirections; &A->b is a pointer to A with an offset. */ if (nb_derefs_ >= 0) { ProbeChecker checker = ProbeChecker(M->getBase(), ptregs_, track_helpers_, is_assign_); if (checker.needs_probe() && checker.get_nb_derefs() == 0) { needs_probe_ = true; return false; } } nb_derefs_++; } return true; } bool VisitUnaryOperator(UnaryOperator *E) { if (E->getOpcode() == UO_Deref) { /* In *A, if A is an external pointer, then *A should be considered one * too. */ ProbeChecker checker = ProbeChecker(E->getSubExpr(), ptregs_, track_helpers_, is_assign_); if (checker.needs_probe() && checker.get_nb_derefs() == 0) { needs_probe_ = true; return false; } nb_derefs_++; } else if (E->getOpcode() == UO_AddrOf) { nb_derefs_--; } return true; } bool VisitDeclRefExpr(DeclRefExpr *E) { if (is_assign_) { // We're looking for an external pointer, regardless of the number of // dereferences. for(auto p : ptregs_) { if (std::get<0>(p) == E->getDecl()) { needs_probe_ = true; nb_derefs_ += std::get<1>(p); return false; } } } else { tuple pt = make_tuple(E->getDecl(), nb_derefs_); if (ptregs_.find(pt) != ptregs_.end()) needs_probe_ = true; } return true; } bool needs_probe() const { return needs_probe_; } bool is_transitive() const { return is_transitive_; } int get_nb_derefs() const { return nb_derefs_; } private: bool needs_probe_; bool is_transitive_; const set> &ptregs_; bool track_helpers_; // Nb of dereferences we go through before finding the external pointer. // A negative number counts the number of addrof. int nb_derefs_; bool is_assign_; }; // Visit a piece of the AST and mark it as needing probe reads class ProbeSetter : public RecursiveASTVisitor { public: explicit ProbeSetter(set> *ptregs, int nb_addrof) : ptregs_(ptregs), nb_derefs_(-nb_addrof) {} bool VisitDeclRefExpr(DeclRefExpr *E) { tuple pt = make_tuple(E->getDecl(), nb_derefs_); ptregs_->insert(pt); return true; } explicit ProbeSetter(set> *ptregs) : ProbeSetter(ptregs, 0) {} bool VisitUnaryOperator(UnaryOperator *E) { if (E->getOpcode() == UO_Deref) nb_derefs_++; return true; } bool VisitMemberExpr(MemberExpr *M) { tuple pt = make_tuple(M->getMemberDecl(), nb_derefs_); ptregs_->insert(pt); return false; } private: set> *ptregs_; // Nb of dereferences we go through before getting to the actual variable. int nb_derefs_; }; MapVisitor::MapVisitor(set &m) : m_(m) {} bool MapVisitor::VisitCallExpr(CallExpr *Call) { if (MemberExpr *Memb = dyn_cast(Call->getCallee()->IgnoreImplicit())) { StringRef memb_name = Memb->getMemberDecl()->getName(); if (DeclRefExpr *Ref = dyn_cast(Memb->getBase())) { if (SectionAttr *A = Ref->getDecl()->getAttr()) { if (!A->getName().startswith("maps")) return true; if (memb_name == "update" || memb_name == "insert") { ProbeChecker checker = ProbeChecker(Call->getArg(1), ptregs_, true, true); if (checker.needs_probe()) m_.insert(Ref->getDecl()); } } } } return true; } ProbeVisitor::ProbeVisitor(ASTContext &C, Rewriter &rewriter, set &m, bool track_helpers) : C(C), rewriter_(rewriter), m_(m), track_helpers_(track_helpers), addrof_stmt_(nullptr), is_addrof_(false) {} bool ProbeVisitor::assignsExtPtr(Expr *E, int *nbAddrOf) { if (IsContextMemberExpr(E)) { *nbAddrOf = 0; return true; } /* If the expression contains a call to another function, we need to visit * that function first to know if a rewrite is necessary (i.e., if the * function returns an external pointer). */ if (!TraverseStmt(E)) return false; ProbeChecker checker = ProbeChecker(E, ptregs_, track_helpers_, true); if (checker.is_transitive()) { // The negative of the number of dereferences is the number of addrof. In // an assignment, if we went through n addrof before getting the external // pointer, then we'll need n dereferences on the left-hand side variable // to get to the external pointer. *nbAddrOf = -checker.get_nb_derefs(); return true; } if (E->IgnoreParenCasts()->getStmtClass() == Stmt::CallExprClass) { CallExpr *Call = dyn_cast(E->IgnoreParenCasts()); if (MemberExpr *Memb = dyn_cast(Call->getCallee()->IgnoreImplicit())) { StringRef memb_name = Memb->getMemberDecl()->getName(); if (DeclRefExpr *Ref = dyn_cast(Memb->getBase())) { if (SectionAttr *A = Ref->getDecl()->getAttr()) { if (!A->getName().startswith("maps")) return false; if (memb_name == "lookup" || memb_name == "lookup_or_init") { if (m_.find(Ref->getDecl()) != m_.end()) { // Retrieved an ext. pointer from a map, mark LHS as ext. pointer. // Pointers from maps always need a single dereference to get the // actual value. The value may be an external pointer but cannot // be a pointer to an external pointer as the verifier prohibits // storing known pointers (to map values, context, the stack, or // the packet) in maps. *nbAddrOf = 1; return true; } } } } } } return false; } bool ProbeVisitor::VisitVarDecl(VarDecl *D) { if (Expr *E = D->getInit()) { int nbAddrOf; if (assignsExtPtr(E, &nbAddrOf)) { // The negative of the number of addrof is the number of dereferences. tuple pt = make_tuple(D, -nbAddrOf); set_ptreg(pt); } } return true; } bool ProbeVisitor::TraverseStmt(Stmt *S) { if (whitelist_.find(S) != whitelist_.end()) return true; auto ret = RecursiveASTVisitor::TraverseStmt(S); if (addrof_stmt_ == S) { addrof_stmt_ = nullptr; is_addrof_ = false; } return ret; } bool ProbeVisitor::VisitCallExpr(CallExpr *Call) { // Skip bpf_probe_read for the third argument if it is an AddrOf. if (VarDecl *V = dyn_cast(Call->getCalleeDecl())) { if (V->getName() == "bpf_probe_read" && Call->getNumArgs() >= 3) { const Expr *E = Call->getArg(2)->IgnoreParenCasts(); whitelist_.insert(E); return true; } } if (FunctionDecl *F = dyn_cast(Call->getCalleeDecl())) { if (F->hasBody()) { unsigned i = 0; for (auto arg : Call->arguments()) { ProbeChecker checker = ProbeChecker(arg, ptregs_, track_helpers_, true); if (checker.needs_probe()) { tuple pt = make_tuple(F->getParamDecl(i), checker.get_nb_derefs()); ptregs_.insert(pt); } ++i; } if (fn_visited_.find(F) == fn_visited_.end()) { fn_visited_.insert(F); /* Maintains a stack of the number of dereferences for the external * pointers returned by each function in the call stack or -1 if the * function didn't return an external pointer. */ ptregs_returned_.push_back(-1); TraverseDecl(F); int nb_derefs = ptregs_returned_.back(); ptregs_returned_.pop_back(); if (nb_derefs != -1) { tuple pt = make_tuple(F, nb_derefs); ptregs_.insert(pt); } } } } return true; } bool ProbeVisitor::VisitReturnStmt(ReturnStmt *R) { /* If this function wasn't called by another, there's no need to check the * return statement for external pointers. */ if (ptregs_returned_.size() == 0) return true; /* Reverse order of traversals. This is needed if, in the return statement, * we're calling a function that's returning an external pointer: we need to * know what the function is returning to decide what this function is * returning. */ if (!TraverseStmt(R->getRetValue())) return false; ProbeChecker checker = ProbeChecker(R->getRetValue(), ptregs_, track_helpers_, true); if (checker.needs_probe()) { int curr_nb_derefs = ptregs_returned_.back(); /* If the function returns external pointers with different levels of * indirection, we handle the case with the highest level of indirection * and leave it to the user to manually handle other cases. */ if (checker.get_nb_derefs() > curr_nb_derefs) { ptregs_returned_.pop_back(); ptregs_returned_.push_back(checker.get_nb_derefs()); } } return true; } bool ProbeVisitor::VisitBinaryOperator(BinaryOperator *E) { if (!E->isAssignmentOp()) return true; // copy probe attribute from RHS to LHS if present int nbAddrOf; if (assignsExtPtr(E->getRHS(), &nbAddrOf)) { ProbeSetter setter(&ptregs_, nbAddrOf); setter.TraverseStmt(E->getLHS()); } return true; } bool ProbeVisitor::VisitUnaryOperator(UnaryOperator *E) { if (E->getOpcode() == UO_AddrOf) { addrof_stmt_ = E; is_addrof_ = true; } if (E->getOpcode() != UO_Deref) return true; if (memb_visited_.find(E) != memb_visited_.end()) return true; Expr *sub = E->getSubExpr(); if (!ProbeChecker(sub, ptregs_, track_helpers_).needs_probe()) return true; memb_visited_.insert(E); string pre, post; pre = "({ typeof(" + E->getType().getAsString() + ") _val; __builtin_memset(&_val, 0, sizeof(_val));"; pre += " bpf_probe_read(&_val, sizeof(_val), (u64)"; post = "); _val; })"; rewriter_.ReplaceText(expansionLoc(E->getOperatorLoc()), 1, pre); rewriter_.InsertTextAfterToken(expansionLoc(GET_ENDLOC(sub)), post); return true; } bool ProbeVisitor::VisitMemberExpr(MemberExpr *E) { if (memb_visited_.find(E) != memb_visited_.end()) return true; Expr *base; SourceLocation rhs_start, member; bool found = false; for (MemberExpr *M = E; M; M = dyn_cast(M->getBase())) { memb_visited_.insert(M); rhs_start = GET_ENDLOC(M); base = M->getBase(); member = M->getMemberLoc(); if (M->isArrow()) { found = true; break; } } if (!found) return true; if (member.isInvalid()) { error(GET_ENDLOC(base), "internal error: MemberLoc is invalid while preparing probe rewrite"); return false; } if (!rewriter_.isRewritable(GET_BEGINLOC(E))) return true; // parent expr has addrof, skip the rewrite, set is_addrof_ to flase so // it won't affect next level of indirect address if (is_addrof_) { is_addrof_ = false; return true; } /* If the base of the dereference is a call to another function, we need to * visit that function first to know if a rewrite is necessary (i.e., if the * function returns an external pointer). */ if (base->IgnoreParenCasts()->getStmtClass() == Stmt::CallExprClass) { CallExpr *Call = dyn_cast(base->IgnoreParenCasts()); if (!TraverseStmt(Call)) return false; } // Checks to see if the expression references something that needs to be run // through bpf_probe_read. if (!ProbeChecker(base, ptregs_, track_helpers_).needs_probe()) return true; string rhs = rewriter_.getRewrittenText(expansionRange(SourceRange(rhs_start, GET_ENDLOC(E)))); string base_type = base->getType()->getPointeeType().getAsString(); string pre, post; pre = "({ typeof(" + E->getType().getAsString() + ") _val; __builtin_memset(&_val, 0, sizeof(_val));"; pre += " bpf_probe_read(&_val, sizeof(_val), (u64)&"; post = rhs + "); _val; })"; rewriter_.InsertText(expansionLoc(GET_BEGINLOC(E)), pre); rewriter_.ReplaceText(expansionRange(SourceRange(member, GET_ENDLOC(E))), post); return true; } bool ProbeVisitor::VisitArraySubscriptExpr(ArraySubscriptExpr *E) { if (memb_visited_.find(E) != memb_visited_.end()) return true; if (!ProbeChecker(E, ptregs_, track_helpers_).needs_probe()) return true; // Parent expr has addrof, skip the rewrite. if (is_addrof_) return true; if (!rewriter_.isRewritable(GET_BEGINLOC(E))) return true; Expr *base = E->getBase(); Expr *idx = E->getIdx(); memb_visited_.insert(E); if (!rewriter_.isRewritable(GET_BEGINLOC(base))) return true; if (!rewriter_.isRewritable(GET_BEGINLOC(idx))) return true; string pre, lbracket, rbracket; LangOptions opts; SourceLocation lbracket_start, lbracket_end; SourceRange lbracket_range; pre = "({ typeof(" + E->getType().getAsString() + ") _val; __builtin_memset(&_val, 0, sizeof(_val));"; pre += " bpf_probe_read(&_val, sizeof(_val), (u64)(("; if (isMemberDereference(base)) { pre += "&"; // If the base of the array subscript is a member dereference, we'll rewrite // both at the same time. addrof_stmt_ = base; is_addrof_ = true; } rewriter_.InsertText(expansionLoc(GET_BEGINLOC(base)), pre); /* Replace left bracket and any space around it. Since Clang doesn't provide * a method to retrieve the left bracket, replace everything from the end of * the base to the start of the index. */ lbracket = ") + ("; lbracket_start = Lexer::getLocForEndOfToken(GET_ENDLOC(base), 1, rewriter_.getSourceMgr(), opts).getLocWithOffset(1); lbracket_end = GET_BEGINLOC(idx).getLocWithOffset(-1); lbracket_range = expansionRange(SourceRange(lbracket_start, lbracket_end)); rewriter_.ReplaceText(lbracket_range, lbracket); rbracket = "))); _val; })"; rewriter_.ReplaceText(expansionLoc(E->getRBracketLoc()), 1, rbracket); return true; } bool ProbeVisitor::isMemberDereference(Expr *E) { if (E->IgnoreParenCasts()->getStmtClass() != Stmt::MemberExprClass) return false; for (MemberExpr *M = dyn_cast(E->IgnoreParenCasts()); M; M = dyn_cast(M->getBase()->IgnoreParenCasts())) { if (M->isArrow()) return true; } return false; } bool ProbeVisitor::IsContextMemberExpr(Expr *E) { if (!E->getType()->isPointerType()) return false; Expr *base; SourceLocation member; bool found = false; MemberExpr *M; Expr *Ex = E->IgnoreParenCasts(); while (Ex->getStmtClass() == Stmt::ArraySubscriptExprClass || Ex->getStmtClass() == Stmt::MemberExprClass) { if (Ex->getStmtClass() == Stmt::ArraySubscriptExprClass) { Ex = dyn_cast(Ex)->getBase()->IgnoreParenCasts(); } else if (Ex->getStmtClass() == Stmt::MemberExprClass) { M = dyn_cast(Ex); base = M->getBase()->IgnoreParenCasts(); member = M->getMemberLoc(); if (M->isArrow()) { found = true; break; } Ex = base; } } if (!found) { return false; } if (member.isInvalid()) { return false; } if (DeclRefExpr *base_expr = dyn_cast(base)) { if (base_expr->getDecl() == ctx_) { return true; } } return false; } SourceRange ProbeVisitor::expansionRange(SourceRange range) { #if LLVM_MAJOR_VERSION >= 7 return rewriter_.getSourceMgr().getExpansionRange(range).getAsRange(); #else return rewriter_.getSourceMgr().getExpansionRange(range); #endif } SourceLocation ProbeVisitor::expansionLoc(SourceLocation loc) { return rewriter_.getSourceMgr().getExpansionLoc(loc); } template DiagnosticBuilder ProbeVisitor::error(SourceLocation loc, const char (&fmt)[N]) { unsigned int diag_id = C.getDiagnostics().getCustomDiagID(DiagnosticsEngine::Error, fmt); return C.getDiagnostics().Report(loc, diag_id); } BTypeVisitor::BTypeVisitor(ASTContext &C, BFrontendAction &fe) : C(C), diag_(C.getDiagnostics()), fe_(fe), rewriter_(fe.rewriter()), out_(llvm::errs()) {} void BTypeVisitor::genParamDirectAssign(FunctionDecl *D, string& preamble, const char **calling_conv_regs) { for (size_t idx = 0; idx < fn_args_.size(); idx++) { ParmVarDecl *arg = fn_args_[idx]; if (idx >= 1) { // Move the args into a preamble section where the same params are // declared and initialized from pt_regs. // Todo: this init should be done only when the program requests it. string text = rewriter_.getRewrittenText(expansionRange(arg->getSourceRange())); arg->addAttr(UnavailableAttr::CreateImplicit(C, "ptregs")); size_t d = idx - 1; const char *reg = calling_conv_regs[d]; preamble += " " + text + " = " + fn_args_[0]->getName().str() + "->" + string(reg) + ";"; } } } void BTypeVisitor::genParamIndirectAssign(FunctionDecl *D, string& preamble, const char **calling_conv_regs) { string new_ctx; for (size_t idx = 0; idx < fn_args_.size(); idx++) { ParmVarDecl *arg = fn_args_[idx]; if (idx == 0) { new_ctx = "__" + arg->getName().str(); preamble += " struct pt_regs * " + new_ctx + " = " + arg->getName().str() + "->" + string(calling_conv_regs[0]) + ";"; } else { // Move the args into a preamble section where the same params are // declared and initialized from pt_regs. // Todo: this init should be done only when the program requests it. string text = rewriter_.getRewrittenText(expansionRange(arg->getSourceRange())); size_t d = idx - 1; const char *reg = calling_conv_regs[d]; preamble += "\n " + text + ";"; preamble += " bpf_probe_read(&" + arg->getName().str() + ", sizeof(" + arg->getName().str() + "), &" + new_ctx + "->" + string(reg) + ");"; } } } void BTypeVisitor::rewriteFuncParam(FunctionDecl *D) { const char **calling_conv_regs = get_call_conv(); string preamble = "{\n"; if (D->param_size() > 1) { // If function prefix is "syscall__" or "kprobe____x64_sys_", // the function will attach to a kprobe syscall function. // Guard parameter assiggnment with CONFIG_ARCH_HAS_SYSCALL_WRAPPER. // For __x64_sys_* syscalls, this is always true, but we guard // it in case of "syscall__" for other architectures. if (strncmp(D->getName().str().c_str(), "syscall__", 9) == 0 || strncmp(D->getName().str().c_str(), "kprobe____x64_sys_", 18) == 0) { preamble += "#ifdef CONFIG_ARCH_HAS_SYSCALL_WRAPPER\n"; genParamIndirectAssign(D, preamble, calling_conv_regs); preamble += "\n#else\n"; genParamDirectAssign(D, preamble, calling_conv_regs); preamble += "\n#endif\n"; } else { genParamDirectAssign(D, preamble, calling_conv_regs); } rewriter_.ReplaceText( expansionRange(SourceRange(GET_ENDLOC(D->getParamDecl(0)), GET_ENDLOC(D->getParamDecl(D->getNumParams() - 1)))), fn_args_[0]->getName()); } // for each trace argument, convert the variable from ptregs to something on stack if (CompoundStmt *S = dyn_cast(D->getBody())) rewriter_.ReplaceText(S->getLBracLoc(), 1, preamble); } bool BTypeVisitor::VisitFunctionDecl(FunctionDecl *D) { // put each non-static non-inline function decl in its own section, to be // extracted by the MemoryManager auto real_start_loc = rewriter_.getSourceMgr().getFileLoc(GET_BEGINLOC(D)); if (fe_.is_rewritable_ext_func(D)) { current_fn_ = D->getName(); string bd = rewriter_.getRewrittenText(expansionRange(D->getSourceRange())); fe_.func_src_.set_src(current_fn_, bd); fe_.func_range_[current_fn_] = expansionRange(D->getSourceRange()); string attr = string("__attribute__((section(\"") + BPF_FN_PREFIX + D->getName().str() + "\")))\n"; rewriter_.InsertText(real_start_loc, attr); if (D->param_size() > MAX_CALLING_CONV_REGS + 1) { error(GET_BEGINLOC(D->getParamDecl(MAX_CALLING_CONV_REGS + 1)), "too many arguments, bcc only supports in-register parameters"); return false; } fn_args_.clear(); for (auto arg_it = D->param_begin(); arg_it != D->param_end(); arg_it++) { auto *arg = *arg_it; if (arg->getName() == "") { error(GET_ENDLOC(arg), "arguments to BPF program definition must be named"); return false; } fn_args_.push_back(arg); } rewriteFuncParam(D); } else if (D->hasBody() && rewriter_.getSourceMgr().getFileID(real_start_loc) == rewriter_.getSourceMgr().getMainFileID()) { // rewritable functions that are static should be always treated as helper rewriter_.InsertText(real_start_loc, "__attribute__((always_inline))\n"); } return true; } // Reverse the order of call traversal so that parameters inside of // function calls will get rewritten before the call itself, otherwise // text mangling will result. bool BTypeVisitor::TraverseCallExpr(CallExpr *Call) { for (auto child : Call->children()) if (!TraverseStmt(child)) return false; if (!WalkUpFromCallExpr(Call)) return false; return true; } // convert calls of the type: // table.foo(&key) // to: // bpf_table_foo_elem(bpf_pseudo_fd(table), &key [,&leaf]) bool BTypeVisitor::VisitCallExpr(CallExpr *Call) { // make sure node is a reference to a bpf table, which is assured by the // presence of the section("maps/") GNU __attribute__ if (MemberExpr *Memb = dyn_cast(Call->getCallee()->IgnoreImplicit())) { StringRef memb_name = Memb->getMemberDecl()->getName(); if (DeclRefExpr *Ref = dyn_cast(Memb->getBase())) { if (SectionAttr *A = Ref->getDecl()->getAttr()) { if (!A->getName().startswith("maps")) return true; string args = rewriter_.getRewrittenText(expansionRange(SourceRange(GET_BEGINLOC(Call->getArg(0)), GET_ENDLOC(Call->getArg(Call->getNumArgs() - 1))))); // find the table fd, which was opened at declaration time TableStorage::iterator desc; Path local_path({fe_.id(), Ref->getDecl()->getName()}); Path global_path({Ref->getDecl()->getName()}); if (!fe_.table_storage().Find(local_path, desc)) { if (!fe_.table_storage().Find(global_path, desc)) { error(GET_ENDLOC(Ref), "bpf_table %0 failed to open") << Ref->getDecl()->getName(); return false; } } string fd = to_string(desc->second.fd); string prefix, suffix; string txt; auto rewrite_start = GET_BEGINLOC(Call); auto rewrite_end = GET_ENDLOC(Call); if (memb_name == "lookup_or_init") { string name = Ref->getDecl()->getName(); string arg0 = rewriter_.getRewrittenText(expansionRange(Call->getArg(0)->getSourceRange())); string arg1 = rewriter_.getRewrittenText(expansionRange(Call->getArg(1)->getSourceRange())); string lookup = "bpf_map_lookup_elem_(bpf_pseudo_fd(1, " + fd + ")"; string update = "bpf_map_update_elem_(bpf_pseudo_fd(1, " + fd + ")"; txt = "({typeof(" + name + ".leaf) *leaf = " + lookup + ", " + arg0 + "); "; txt += "if (!leaf) {"; txt += " " + update + ", " + arg0 + ", " + arg1 + ", BPF_NOEXIST);"; txt += " leaf = " + lookup + ", " + arg0 + ");"; txt += " if (!leaf) return 0;"; txt += "}"; txt += "leaf;})"; } else if (memb_name == "increment") { string name = Ref->getDecl()->getName(); string arg0 = rewriter_.getRewrittenText(expansionRange(Call->getArg(0)->getSourceRange())); string increment_value = "1"; if (Call->getNumArgs() == 2) { increment_value = rewriter_.getRewrittenText(expansionRange(Call->getArg(1)->getSourceRange())); } string lookup = "bpf_map_lookup_elem_(bpf_pseudo_fd(1, " + fd + ")"; string update = "bpf_map_update_elem_(bpf_pseudo_fd(1, " + fd + ")"; txt = "({ typeof(" + name + ".key) _key = " + arg0 + "; "; txt += "typeof(" + name + ".leaf) *_leaf = " + lookup + ", &_key); "; txt += "if (_leaf) (*_leaf) += " + increment_value + ";"; if (desc->second.type == BPF_MAP_TYPE_HASH) { txt += "else { typeof(" + name + ".leaf) _zleaf; __builtin_memset(&_zleaf, 0, sizeof(_zleaf)); "; txt += "_zleaf += " + increment_value + ";"; txt += update + ", &_key, &_zleaf, BPF_NOEXIST); } "; } txt += "})"; } else if (memb_name == "perf_submit") { string name = Ref->getDecl()->getName(); string arg0 = rewriter_.getRewrittenText(expansionRange(Call->getArg(0)->getSourceRange())); string args_other = rewriter_.getRewrittenText(expansionRange(SourceRange(GET_BEGINLOC(Call->getArg(1)), GET_ENDLOC(Call->getArg(2))))); txt = "bpf_perf_event_output(" + arg0 + ", bpf_pseudo_fd(1, " + fd + ")"; txt += ", CUR_CPU_IDENTIFIER, " + args_other + ")"; } else if (memb_name == "perf_submit_skb") { string skb = rewriter_.getRewrittenText(expansionRange(Call->getArg(0)->getSourceRange())); string skb_len = rewriter_.getRewrittenText(expansionRange(Call->getArg(1)->getSourceRange())); string meta = rewriter_.getRewrittenText(expansionRange(Call->getArg(2)->getSourceRange())); string meta_len = rewriter_.getRewrittenText(expansionRange(Call->getArg(3)->getSourceRange())); txt = "bpf_perf_event_output(" + skb + ", " + "bpf_pseudo_fd(1, " + fd + "), " + "((__u64)" + skb_len + " << 32) | BPF_F_CURRENT_CPU, " + meta + ", " + meta_len + ");"; } else if (memb_name == "get_stackid") { if (desc->second.type == BPF_MAP_TYPE_STACK_TRACE) { string arg0 = rewriter_.getRewrittenText(expansionRange(Call->getArg(0)->getSourceRange())); txt = "bcc_get_stackid("; txt += "bpf_pseudo_fd(1, " + fd + "), " + arg0; rewrite_end = GET_ENDLOC(Call->getArg(0)); } else { error(GET_BEGINLOC(Call), "get_stackid only available on stacktrace maps"); return false; } } else { if (memb_name == "lookup") { prefix = "bpf_map_lookup_elem"; suffix = ")"; } else if (memb_name == "update") { prefix = "bpf_map_update_elem"; suffix = ", BPF_ANY)"; } else if (memb_name == "insert") { if (desc->second.type == BPF_MAP_TYPE_ARRAY) { warning(GET_BEGINLOC(Call), "all element of an array already exist; insert() will have no effect"); } prefix = "bpf_map_update_elem"; suffix = ", BPF_NOEXIST)"; } else if (memb_name == "delete") { prefix = "bpf_map_delete_elem"; suffix = ")"; } else if (memb_name == "call") { prefix = "bpf_tail_call_"; suffix = ")"; } else if (memb_name == "perf_read") { prefix = "bpf_perf_event_read"; suffix = ")"; } else if (memb_name == "perf_counter_value") { prefix = "bpf_perf_event_read_value"; suffix = ")"; } else if (memb_name == "check_current_task") { prefix = "bpf_current_task_under_cgroup"; suffix = ")"; } else if (memb_name == "redirect_map") { prefix = "bpf_redirect_map"; suffix = ")"; } else { error(GET_BEGINLOC(Call), "invalid bpf_table operation %0") << memb_name; return false; } prefix += "((void *)bpf_pseudo_fd(1, " + fd + "), "; txt = prefix + args + suffix; } if (!rewriter_.isRewritable(rewrite_start) || !rewriter_.isRewritable(rewrite_end)) { error(GET_BEGINLOC(Call), "cannot use map function inside a macro"); return false; } rewriter_.ReplaceText(expansionRange(SourceRange(rewrite_start, rewrite_end)), txt); return true; } } } else if (Call->getCalleeDecl()) { NamedDecl *Decl = dyn_cast(Call->getCalleeDecl()); if (!Decl) return true; if (AsmLabelAttr *A = Decl->getAttr()) { // Functions with the tag asm("llvm.bpf.extra") are implemented in the // rewriter rather than as a macro since they may also include nested // rewrites, and clang::Rewriter does not support rewrites in macros, // unless one preprocesses the entire source file. if (A->getLabel() == "llvm.bpf.extra") { if (!rewriter_.isRewritable(GET_BEGINLOC(Call))) { error(GET_BEGINLOC(Call), "cannot use builtin inside a macro"); return false; } vector args; for (auto arg : Call->arguments()) args.push_back(rewriter_.getRewrittenText(expansionRange(arg->getSourceRange()))); string text; if (Decl->getName() == "incr_cksum_l3") { text = "bpf_l3_csum_replace_(" + fn_args_[0]->getName().str() + ", (u64)"; text += args[0] + ", " + args[1] + ", " + args[2] + ", sizeof(" + args[2] + "))"; rewriter_.ReplaceText(expansionRange(Call->getSourceRange()), text); } else if (Decl->getName() == "incr_cksum_l4") { text = "bpf_l4_csum_replace_(" + fn_args_[0]->getName().str() + ", (u64)"; text += args[0] + ", " + args[1] + ", " + args[2]; text += ", ((" + args[3] + " & 0x1) << 4) | sizeof(" + args[2] + "))"; rewriter_.ReplaceText(expansionRange(Call->getSourceRange()), text); } else if (Decl->getName() == "bpf_trace_printk") { checkFormatSpecifiers(args[0], GET_BEGINLOC(Call->getArg(0))); // #define bpf_trace_printk(fmt, args...) // ({ char _fmt[] = fmt; bpf_trace_printk_(_fmt, sizeof(_fmt), args...); }) text = "({ char _fmt[] = " + args[0] + "; bpf_trace_printk_(_fmt, sizeof(_fmt)"; if (args.size() <= 1) { text += "); })"; rewriter_.ReplaceText(expansionRange(Call->getSourceRange()), text); } else { rewriter_.ReplaceText(expansionRange(SourceRange(GET_BEGINLOC(Call), GET_ENDLOC(Call->getArg(0)))), text); rewriter_.InsertTextAfter(GET_ENDLOC(Call), "); }"); } } else if (Decl->getName() == "bpf_num_cpus") { int numcpu = sysconf(_SC_NPROCESSORS_ONLN); if (numcpu <= 0) numcpu = 1; text = to_string(numcpu); rewriter_.ReplaceText(expansionRange(Call->getSourceRange()), text); } else if (Decl->getName() == "bpf_usdt_readarg_p") { text = "({ u64 __addr = 0x0; "; text += "_bpf_readarg_" + current_fn_ + "_" + args[0] + "(" + args[1] + ", &__addr, sizeof(__addr));"; text += "bpf_probe_read(" + args[2] + ", " + args[3] + ", (void *)__addr);"; text += "})"; rewriter_.ReplaceText(expansionRange(Call->getSourceRange()), text); } else if (Decl->getName() == "bpf_usdt_readarg") { text = "_bpf_readarg_" + current_fn_ + "_" + args[0] + "(" + args[1] + ", " + args[2] + ", sizeof(*(" + args[2] + ")))"; rewriter_.ReplaceText(expansionRange(Call->getSourceRange()), text); } } } else if (FunctionDecl *F = dyn_cast(Decl)) { if (F->isExternallyVisible() && !F->getBuiltinID()) { auto start_loc = rewriter_.getSourceMgr().getFileLoc(GET_BEGINLOC(Decl)); if (rewriter_.getSourceMgr().getFileID(start_loc) == rewriter_.getSourceMgr().getMainFileID()) { error(GET_BEGINLOC(Call), "cannot call non-static helper function"); return false; } } } } return true; } bool BTypeVisitor::checkFormatSpecifiers(const string& fmt, SourceLocation loc) { unsigned nb_specifiers = 0, i, j; bool has_s = false; for (i = 0; i < fmt.length(); i++) { if (!isascii(fmt[i]) || (!isprint(fmt[i]) && !isspace(fmt[i]))) { warning(loc.getLocWithOffset(i), "unrecognized character"); return false; } if (fmt[i] != '%') continue; if (nb_specifiers >= 3) { warning(loc.getLocWithOffset(i), "cannot use more than 3 conversion specifiers"); return false; } nb_specifiers++; i++; if (fmt[i] == 'l') { i++; } else if (fmt[i] == 'p' || fmt[i] == 's') { i++; if (!isspace(fmt[i]) && !ispunct(fmt[i]) && fmt[i] != 0) { warning(loc.getLocWithOffset(i - 2), "only %%d %%u %%x %%ld %%lu %%lx %%lld %%llu %%llx %%p %%s conversion specifiers allowed"); return false; } if (fmt[i - 1] == 's') { if (has_s) { warning(loc.getLocWithOffset(i - 2), "cannot use several %%s conversion specifiers"); return false; } has_s = true; } continue; } j = 1; if (fmt[i] == 'l') { i++; j++; } if (fmt[i] != 'd' && fmt[i] != 'u' && fmt[i] != 'x') { warning(loc.getLocWithOffset(i - j), "only %%d %%u %%x %%ld %%lu %%lx %%lld %%llu %%llx %%p %%s conversion specifiers allowed"); return false; } } return true; } bool BTypeVisitor::VisitBinaryOperator(BinaryOperator *E) { if (!E->isAssignmentOp()) return true; Expr *LHS = E->getLHS()->IgnoreImplicit(); if (MemberExpr *Memb = dyn_cast(LHS)) { if (DeclRefExpr *Base = dyn_cast(Memb->getBase()->IgnoreImplicit())) { if (DeprecatedAttr *A = Base->getDecl()->getAttr()) { if (A->getMessage() == "packet") { if (FieldDecl *F = dyn_cast(Memb->getMemberDecl())) { if (!rewriter_.isRewritable(GET_BEGINLOC(E))) { error(GET_BEGINLOC(E), "cannot use \"packet\" header type inside a macro"); return false; } uint64_t ofs = C.getFieldOffset(F); uint64_t sz = F->isBitField() ? F->getBitWidthValue(C) : C.getTypeSize(F->getType()); string base = rewriter_.getRewrittenText(expansionRange(Base->getSourceRange())); string text = "bpf_dins_pkt(" + fn_args_[0]->getName().str() + ", (u64)" + base + "+" + to_string(ofs >> 3) + ", " + to_string(ofs & 0x7) + ", " + to_string(sz) + ","; rewriter_.ReplaceText(expansionRange(SourceRange(GET_BEGINLOC(E), E->getOperatorLoc())), text); rewriter_.InsertTextAfterToken(GET_ENDLOC(E), ")"); } } } } } return true; } bool BTypeVisitor::VisitImplicitCastExpr(ImplicitCastExpr *E) { // use dext only for RValues if (E->getCastKind() != CK_LValueToRValue) return true; MemberExpr *Memb = dyn_cast(E->IgnoreImplicit()); if (!Memb) return true; Expr *Base = Memb->getBase()->IgnoreImplicit(); if (DeclRefExpr *Ref = dyn_cast(Base)) { if (DeprecatedAttr *A = Ref->getDecl()->getAttr()) { if (A->getMessage() == "packet") { if (FieldDecl *F = dyn_cast(Memb->getMemberDecl())) { if (!rewriter_.isRewritable(GET_BEGINLOC(E))) { error(GET_BEGINLOC(E), "cannot use \"packet\" header type inside a macro"); return false; } uint64_t ofs = C.getFieldOffset(F); uint64_t sz = F->isBitField() ? F->getBitWidthValue(C) : C.getTypeSize(F->getType()); string text = "bpf_dext_pkt(" + fn_args_[0]->getName().str() + ", (u64)" + Ref->getDecl()->getName().str() + "+" + to_string(ofs >> 3) + ", " + to_string(ofs & 0x7) + ", " + to_string(sz) + ")"; rewriter_.ReplaceText(expansionRange(E->getSourceRange()), text); } } } } return true; } SourceRange BTypeVisitor::expansionRange(SourceRange range) { #if LLVM_MAJOR_VERSION >= 7 return rewriter_.getSourceMgr().getExpansionRange(range).getAsRange(); #else return rewriter_.getSourceMgr().getExpansionRange(range); #endif } template DiagnosticBuilder BTypeVisitor::error(SourceLocation loc, const char (&fmt)[N]) { unsigned int diag_id = C.getDiagnostics().getCustomDiagID(DiagnosticsEngine::Error, fmt); return C.getDiagnostics().Report(loc, diag_id); } template DiagnosticBuilder BTypeVisitor::warning(SourceLocation loc, const char (&fmt)[N]) { unsigned int diag_id = C.getDiagnostics().getCustomDiagID(DiagnosticsEngine::Warning, fmt); return C.getDiagnostics().Report(loc, diag_id); } int64_t BTypeVisitor::getFieldValue(VarDecl *Decl, FieldDecl *FDecl, int64_t OrigFValue) { unsigned idx = FDecl->getFieldIndex(); if (auto I = dyn_cast_or_null(Decl->getInit())) { #if LLVM_MAJOR_VERSION >= 8 Expr::EvalResult res; if (I->getInit(idx)->EvaluateAsInt(res, C)) { return res.Val.getInt().getExtValue(); } #else llvm::APSInt res; if (I->getInit(idx)->EvaluateAsInt(res, C)) { return res.getExtValue(); } #endif } return OrigFValue; } // Open table FDs when bpf tables (as denoted by section("maps*") attribute) // are declared. bool BTypeVisitor::VisitVarDecl(VarDecl *Decl) { const RecordType *R = Decl->getType()->getAs(); if (SectionAttr *A = Decl->getAttr()) { if (!A->getName().startswith("maps")) return true; if (!R) { error(GET_ENDLOC(Decl), "invalid type for bpf_table, expect struct"); return false; } const RecordDecl *RD = R->getDecl()->getDefinition(); TableDesc table; TableStorage::iterator table_it; table.name = Decl->getName(); Path local_path({fe_.id(), table.name}); Path maps_ns_path({"ns", fe_.maps_ns(), table.name}); Path global_path({table.name}); QualType key_type, leaf_type; unsigned i = 0; for (auto F : RD->fields()) { if (F->getType().getTypePtr()->isIncompleteType()) { error(GET_BEGINLOC(F), "unknown type"); return false; } size_t sz = C.getTypeSize(F->getType()) >> 3; if (F->getName() == "key") { if (sz == 0) { error(GET_BEGINLOC(F), "invalid zero-sized leaf"); return false; } table.key_size = sz; key_type = F->getType(); } else if (F->getName() == "leaf") { if (sz == 0) { error(GET_BEGINLOC(F), "invalid zero-sized leaf"); return false; } table.leaf_size = sz; leaf_type = F->getType(); } else if (F->getName() == "max_entries") { table.max_entries = getFieldValue(Decl, F, table.max_entries); } else if (F->getName() == "flags") { table.flags = getFieldValue(Decl, F, table.flags); } ++i; } bpf_map_type map_type = BPF_MAP_TYPE_UNSPEC; if (A->getName() == "maps/hash") { map_type = BPF_MAP_TYPE_HASH; } else if (A->getName() == "maps/array") { map_type = BPF_MAP_TYPE_ARRAY; } else if (A->getName() == "maps/percpu_hash") { map_type = BPF_MAP_TYPE_PERCPU_HASH; } else if (A->getName() == "maps/percpu_array") { map_type = BPF_MAP_TYPE_PERCPU_ARRAY; } else if (A->getName() == "maps/lru_hash") { map_type = BPF_MAP_TYPE_LRU_HASH; } else if (A->getName() == "maps/lru_percpu_hash") { map_type = BPF_MAP_TYPE_LRU_PERCPU_HASH; } else if (A->getName() == "maps/lpm_trie") { map_type = BPF_MAP_TYPE_LPM_TRIE; } else if (A->getName() == "maps/histogram") { map_type = BPF_MAP_TYPE_HASH; if (key_type->isSpecificBuiltinType(BuiltinType::Int)) map_type = BPF_MAP_TYPE_ARRAY; if (!leaf_type->isSpecificBuiltinType(BuiltinType::ULongLong)) error(GET_BEGINLOC(Decl), "histogram leaf type must be u64, got %0") << leaf_type; } else if (A->getName() == "maps/prog") { map_type = BPF_MAP_TYPE_PROG_ARRAY; } else if (A->getName() == "maps/perf_output") { map_type = BPF_MAP_TYPE_PERF_EVENT_ARRAY; int numcpu = get_possible_cpus().size(); if (numcpu <= 0) numcpu = 1; table.max_entries = numcpu; } else if (A->getName() == "maps/perf_array") { map_type = BPF_MAP_TYPE_PERF_EVENT_ARRAY; } else if (A->getName() == "maps/cgroup_array") { map_type = BPF_MAP_TYPE_CGROUP_ARRAY; } else if (A->getName() == "maps/stacktrace") { map_type = BPF_MAP_TYPE_STACK_TRACE; } else if (A->getName() == "maps/devmap") { map_type = BPF_MAP_TYPE_DEVMAP; } else if (A->getName() == "maps/cpumap") { map_type = BPF_MAP_TYPE_CPUMAP; } else if (A->getName() == "maps/extern") { if (!fe_.table_storage().Find(maps_ns_path, table_it)) { if (!fe_.table_storage().Find(global_path, table_it)) { error(GET_BEGINLOC(Decl), "reference to undefined table"); return false; } } table = table_it->second.dup(); table.is_extern = true; } else if (A->getName() == "maps/export") { if (table.name.substr(0, 2) == "__") table.name = table.name.substr(2); Path local_path({fe_.id(), table.name}); Path global_path({table.name}); if (!fe_.table_storage().Find(local_path, table_it)) { error(GET_BEGINLOC(Decl), "reference to undefined table"); return false; } fe_.table_storage().Insert(global_path, table_it->second.dup()); return true; } else if(A->getName() == "maps/shared") { if (table.name.substr(0, 2) == "__") table.name = table.name.substr(2); Path local_path({fe_.id(), table.name}); Path maps_ns_path({"ns", fe_.maps_ns(), table.name}); if (!fe_.table_storage().Find(local_path, table_it)) { error(GET_BEGINLOC(Decl), "reference to undefined table"); return false; } fe_.table_storage().Insert(maps_ns_path, table_it->second.dup()); return true; } if (!table.is_extern) { if (map_type == BPF_MAP_TYPE_UNSPEC) { error(GET_BEGINLOC(Decl), "unsupported map type: %0") << A->getName(); return false; } table.type = map_type; table.fd = bpf_create_map(map_type, table.name.c_str(), table.key_size, table.leaf_size, table.max_entries, table.flags); } if (table.fd < 0) { error(GET_BEGINLOC(Decl), "could not open bpf map: %0\nis %1 map type enabled in your kernel?") << strerror(errno) << A->getName(); return false; } if (!table.is_extern) fe_.table_storage().VisitMapType(table, C, key_type, leaf_type); fe_.table_storage().Insert(local_path, move(table)); } else if (const PointerType *P = Decl->getType()->getAs()) { // if var is a pointer to a packet type, clone the annotation into the var // decl so that the packet dext/dins rewriter can catch it if (const RecordType *RT = P->getPointeeType()->getAs()) { if (const RecordDecl *RD = RT->getDecl()->getDefinition()) { if (DeprecatedAttr *DA = RD->getAttr()) { if (DA->getMessage() == "packet") { Decl->addAttr(DA->clone(C)); } } } } } return true; } // First traversal of AST to retrieve maps with external pointers. BTypeConsumer::BTypeConsumer(ASTContext &C, BFrontendAction &fe, Rewriter &rewriter, set &m) : fe_(fe), map_visitor_(m), btype_visitor_(C, fe), probe_visitor1_(C, rewriter, m, true), probe_visitor2_(C, rewriter, m, false) {} void BTypeConsumer::HandleTranslationUnit(ASTContext &Context) { DeclContext::decl_iterator it; DeclContext *DC = TranslationUnitDecl::castToDeclContext(Context.getTranslationUnitDecl()); /** * In a first traversal, ProbeVisitor tracks external pointers identified * through each function's arguments and replaces their dereferences with * calls to bpf_probe_read. It also passes all identified pointers to * external addresses to MapVisitor. */ for (it = DC->decls_begin(); it != DC->decls_end(); it++) { Decl *D = *it; if (FunctionDecl *F = dyn_cast(D)) { if (fe_.is_rewritable_ext_func(F)) { for (auto arg : F->parameters()) { if (arg == F->getParamDecl(0)) { /** * Limit tracing of pointers from context to tracing contexts. * We're whitelisting instead of blacklisting to avoid issues with * existing programs if new context types are added in the future. */ string type = arg->getType().getAsString(); if (type == "struct pt_regs *" || type == "struct bpf_raw_tracepoint_args *" || type.substr(0, 19) == "struct tracepoint__") probe_visitor1_.set_ctx(arg); } else if (!arg->getType()->isFundamentalType()) { tuple pt = make_tuple(arg, 0); probe_visitor1_.set_ptreg(pt); } } probe_visitor1_.TraverseDecl(D); for (auto ptreg : probe_visitor1_.get_ptregs()) { map_visitor_.set_ptreg(ptreg); } } } } /** * MapVisitor uses external pointers identified by the first ProbeVisitor * traversal to identify all maps with external pointers as values. * MapVisitor runs only after ProbeVisitor finished its traversal of the * whole translation unit to clearly separate the role of each ProbeVisitor's * traversal: the first tracks external pointers from function arguments, * whereas the second tracks external pointers from maps. Without this clear * separation, ProbeVisitor might attempt to replace several times the same * dereferences. */ for (it = DC->decls_begin(); it != DC->decls_end(); it++) { Decl *D = *it; if (FunctionDecl *F = dyn_cast(D)) { if (fe_.is_rewritable_ext_func(F)) { map_visitor_.TraverseDecl(D); } } } /** * In a second traversal, ProbeVisitor tracks pointers passed through the * maps identified by MapVisitor and replaces their dereferences with calls * to bpf_probe_read. * This last traversal runs after MapVisitor went through an entire * translation unit, to ensure maps with external pointers have all been * identified. */ for (it = DC->decls_begin(); it != DC->decls_end(); it++) { Decl *D = *it; if (FunctionDecl *F = dyn_cast(D)) { if (fe_.is_rewritable_ext_func(F)) { probe_visitor2_.TraverseDecl(D); } } btype_visitor_.TraverseDecl(D); } } BFrontendAction::BFrontendAction(llvm::raw_ostream &os, unsigned flags, TableStorage &ts, const std::string &id, const std::string &main_path, FuncSource &func_src, std::string &mod_src, const std::string &maps_ns) : os_(os), flags_(flags), ts_(ts), id_(id), maps_ns_(maps_ns), rewriter_(new Rewriter), main_path_(main_path), func_src_(func_src), mod_src_(mod_src) {} bool BFrontendAction::is_rewritable_ext_func(FunctionDecl *D) { StringRef file_name = rewriter_->getSourceMgr().getFilename(GET_BEGINLOC(D)); return (D->isExternallyVisible() && D->hasBody() && (file_name.empty() || file_name == main_path_)); } void BFrontendAction::DoMiscWorkAround() { // In 4.16 and later, CONFIG_CC_STACKPROTECTOR is moved out of Kconfig and into // Makefile. It will be set depending on CONFIG_CC_STACKPROTECTOR_{AUTO|REGULAR|STRONG}. // CONFIG_CC_STACKPROTECTOR is still used in various places, e.g., struct task_struct, // to guard certain fields. The workaround here intends to define // CONFIG_CC_STACKPROTECTOR properly based on other configs, so it relieved any bpf // program (using task_struct, etc.) of patching the below code. rewriter_->getEditBuffer(rewriter_->getSourceMgr().getMainFileID()).InsertText(0, "#if defined(BPF_LICENSE)\n" "#error BPF_LICENSE cannot be specified through cflags\n" "#endif\n" "#if !defined(CONFIG_CC_STACKPROTECTOR)\n" "#if defined(CONFIG_CC_STACKPROTECTOR_AUTO) \\\n" " || defined(CONFIG_CC_STACKPROTECTOR_REGULAR) \\\n" " || defined(CONFIG_CC_STACKPROTECTOR_STRONG)\n" "#define CONFIG_CC_STACKPROTECTOR\n" "#endif\n" "#endif\n", false); rewriter_->getEditBuffer(rewriter_->getSourceMgr().getMainFileID()).InsertTextAfter( rewriter_->getSourceMgr().getBuffer(rewriter_->getSourceMgr().getMainFileID())->getBufferSize(), "\n#include \n"); } void BFrontendAction::EndSourceFileAction() { // Additional misc rewrites DoMiscWorkAround(); if (flags_ & DEBUG_PREPROCESSOR) rewriter_->getEditBuffer(rewriter_->getSourceMgr().getMainFileID()).write(llvm::errs()); if (flags_ & DEBUG_SOURCE) { llvm::raw_string_ostream tmp_os(mod_src_); rewriter_->getEditBuffer(rewriter_->getSourceMgr().getMainFileID()) .write(tmp_os); } for (auto func : func_range_) { auto f = func.first; string bd = rewriter_->getRewrittenText(func_range_[f]); func_src_.set_src_rewritten(f, bd); } rewriter_->getEditBuffer(rewriter_->getSourceMgr().getMainFileID()).write(os_); os_.flush(); } unique_ptr BFrontendAction::CreateASTConsumer(CompilerInstance &Compiler, llvm::StringRef InFile) { rewriter_->setSourceMgr(Compiler.getSourceManager(), Compiler.getLangOpts()); vector> consumers; consumers.push_back(unique_ptr(new BTypeConsumer(Compiler.getASTContext(), *this, *rewriter_, m_))); return unique_ptr(new MultiplexConsumer(std::move(consumers))); } }