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diff -up chromium-88.0.4324.96/sandbox/linux/seccomp-bpf-helpers/baseline_policy.cc.fstatfix chromium-88.0.4324.96/sandbox/linux/seccomp-bpf-helpers/baseline_policy.cc
--- chromium-88.0.4324.96/sandbox/linux/seccomp-bpf-helpers/baseline_policy.cc.fstatfix 2021-01-25 10:11:45.427436398 -0500
+++ chromium-88.0.4324.96/sandbox/linux/seccomp-bpf-helpers/baseline_policy.cc 2021-01-25 10:12:51.337699003 -0500
@@ -257,6 +257,18 @@ ResultExpr EvaluateSyscallImpl(int fs_de
return RestrictKillTarget(current_pid, sysno);
}
+#if defined(__NR_newfstatat)
+ if (sysno == __NR_newfstatat) {
+ return RewriteFstatatSIGSYS();
+ }
+#endif
+
+#if defined(__NR_fstatat64)
+ if (sysno == __NR_fstatat64) {
+ return RewriteFstatatSIGSYS();
+ }
+#endif
+
if (SyscallSets::IsFileSystem(sysno) ||
SyscallSets::IsCurrentDirectory(sysno)) {
return Error(fs_denied_errno);
diff -up chromium-88.0.4324.96/sandbox/linux/seccomp-bpf-helpers/sigsys_handlers.cc.fstatfix chromium-88.0.4324.96/sandbox/linux/seccomp-bpf-helpers/sigsys_handlers.cc
--- chromium-88.0.4324.96/sandbox/linux/seccomp-bpf-helpers/sigsys_handlers.cc.fstatfix 2021-01-25 10:13:10.179774081 -0500
+++ chromium-88.0.4324.96/sandbox/linux/seccomp-bpf-helpers/sigsys_handlers.cc 2021-01-25 10:16:18.790525746 -0500
@@ -6,6 +6,8 @@
#include "sandbox/linux/seccomp-bpf-helpers/sigsys_handlers.h"
+#include <errno.h>
+#include <fcntl.h>
#include <stddef.h>
#include <stdint.h>
#include <string.h>
@@ -355,6 +357,35 @@ intptr_t SIGSYSSchedHandler(const struct
return -ENOSYS;
}
+intptr_t SIGSYSFstatatHandler(const struct arch_seccomp_data& args,
+ void* aux) {
+ switch (args.nr) {
+#if defined(__NR_newfstatat)
+ case __NR_newfstatat:
+#endif
+#if defined(__NR_fstatat64)
+ case __NR_fstatat64:
+#endif
+#if defined(__NR_newfstatat) || defined(__NR_fstatat64)
+ if (*reinterpret_cast<const char *>(args.args[1]) == '\0'
+ && args.args[3] == static_cast<uint64_t>(AT_EMPTY_PATH)) {
+ return sandbox::sys_fstat64(static_cast<int>(args.args[0]),
+ reinterpret_cast<struct stat64 *>(args.args[2]));
+ } else {
+ errno = EACCES;
+ return -1;
+ }
+ break;
+#endif
+ }
+
+ CrashSIGSYS_Handler(args, aux);
+
+ // Should never be reached.
+ RAW_CHECK(false);
+ return -ENOSYS;
+}
+
bpf_dsl::ResultExpr CrashSIGSYS() {
return bpf_dsl::Trap(CrashSIGSYS_Handler, NULL);
}
@@ -387,6 +418,10 @@ bpf_dsl::ResultExpr RewriteSchedSIGSYS()
return bpf_dsl::Trap(SIGSYSSchedHandler, NULL);
}
+bpf_dsl::ResultExpr RewriteFstatatSIGSYS() {
+ return bpf_dsl::Trap(SIGSYSFstatatHandler, NULL);
+}
+
void AllocateCrashKeys() {
#if !defined(OS_NACL_NONSFI)
if (seccomp_crash_key)
diff -up chromium-88.0.4324.96/sandbox/linux/seccomp-bpf-helpers/sigsys_handlers.h.fstatfix chromium-88.0.4324.96/sandbox/linux/seccomp-bpf-helpers/sigsys_handlers.h
--- chromium-88.0.4324.96/sandbox/linux/seccomp-bpf-helpers/sigsys_handlers.h.fstatfix 2021-01-25 10:16:36.982598236 -0500
+++ chromium-88.0.4324.96/sandbox/linux/seccomp-bpf-helpers/sigsys_handlers.h 2021-01-25 10:18:45.705111027 -0500
@@ -62,6 +62,10 @@ SANDBOX_EXPORT intptr_t SIGSYSPtraceFail
// sched_setparam(), sched_setscheduler()
SANDBOX_EXPORT intptr_t SIGSYSSchedHandler(const arch_seccomp_data& args,
void* aux);
+// If the fstatat syscall is actually a disguised fstat, calls the regular fstat
+// syscall, otherwise, crashes in the same way as CrashSIGSYS_Handler.
+SANDBOX_EXPORT intptr_t SIGSYSFstatatHandler(const struct arch_seccomp_data& args,
+ void* aux);
// Variants of the above functions for use with bpf_dsl.
SANDBOX_EXPORT bpf_dsl::ResultExpr CrashSIGSYS();
@@ -72,6 +76,7 @@ SANDBOX_EXPORT bpf_dsl::ResultExpr Crash
SANDBOX_EXPORT bpf_dsl::ResultExpr CrashSIGSYSFutex();
SANDBOX_EXPORT bpf_dsl::ResultExpr CrashSIGSYSPtrace();
SANDBOX_EXPORT bpf_dsl::ResultExpr RewriteSchedSIGSYS();
+SANDBOX_EXPORT bpf_dsl::ResultExpr RewriteFstatatSIGSYS();
// Allocates a crash key so that Seccomp information can be recorded.
void AllocateCrashKeys();
diff -up chromium-88.0.4324.96/sandbox/linux/services/syscall_wrappers.cc.fstatfix chromium-88.0.4324.96/sandbox/linux/services/syscall_wrappers.cc
--- chromium-88.0.4324.96/sandbox/linux/services/syscall_wrappers.cc.fstatfix 2021-01-25 10:18:53.307141311 -0500
+++ chromium-88.0.4324.96/sandbox/linux/services/syscall_wrappers.cc 2021-01-25 10:19:46.982355293 -0500
@@ -261,4 +261,13 @@ int sys_sigaction(int signum,
#endif // defined(MEMORY_SANITIZER)
+SANDBOX_EXPORT int sys_fstat64(int fd, struct stat64 *buf)
+{
+#if defined(__NR_fstat64)
+ return syscall(__NR_fstat64, fd, buf);
+#else
+ return syscall(__NR_fstat, fd, buf);
+#endif
+}
+
} // namespace sandbox
diff -up chromium-88.0.4324.96/sandbox/linux/services/syscall_wrappers.h.fstatfix chromium-88.0.4324.96/sandbox/linux/services/syscall_wrappers.h
--- chromium-88.0.4324.96/sandbox/linux/services/syscall_wrappers.h.fstatfix 2021-01-25 10:19:53.115379741 -0500
+++ chromium-88.0.4324.96/sandbox/linux/services/syscall_wrappers.h 2021-01-25 10:20:45.485588421 -0500
@@ -17,6 +17,7 @@ struct sock_fprog;
struct rlimit64;
struct cap_hdr;
struct cap_data;
+struct stat64;
namespace sandbox {
@@ -84,6 +85,9 @@ SANDBOX_EXPORT int sys_sigaction(int sig
const struct sigaction* act,
struct sigaction* oldact);
+// Recent glibc rewrites fstat to fstatat.
+SANDBOX_EXPORT int sys_fstat64(int fd, struct stat64 *buf);
+
} // namespace sandbox
#endif // SANDBOX_LINUX_SERVICES_SYSCALL_WRAPPERS_H_
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