diff --git a/sandbox/linux/seccomp-bpf-helpers/baseline_policy.cc b/sandbox/linux/seccomp-bpf-helpers/baseline_policy.cc index 05c39f0f5..3a9d6f359 100644 --- a/sandbox/linux/seccomp-bpf-helpers/baseline_policy.cc +++ b/sandbox/linux/seccomp-bpf-helpers/baseline_policy.cc @@ -280,6 +280,18 @@ ResultExpr EvaluateSyscallImpl(int fs_denied_errno, 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 + // memfd_create is considered a file system syscall which below will be denied // with fs_denied_errno, we need memfd_create for Mojo shared memory channels. if (sysno == __NR_memfd_create) { diff --git a/sandbox/linux/seccomp-bpf-helpers/sigsys_handlers.cc b/sandbox/linux/seccomp-bpf-helpers/sigsys_handlers.cc index 76eb32493..09aa3f0b1 100644 --- a/sandbox/linux/seccomp-bpf-helpers/sigsys_handlers.cc +++ b/sandbox/linux/seccomp-bpf-helpers/sigsys_handlers.cc @@ -6,6 +6,8 @@ #include "sandbox/linux/seccomp-bpf-helpers/sigsys_handlers.h" +#include +#include #include #include #include @@ -355,6 +357,35 @@ intptr_t SIGSYSSchedHandler(const struct arch_seccomp_data& args, 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(args.args[1]) == '\0' + && args.args[3] == static_cast(AT_EMPTY_PATH)) { + return sandbox::sys_fstat64(static_cast(args.args[0]), + reinterpret_cast(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 --git a/sandbox/linux/seccomp-bpf-helpers/sigsys_handlers.h b/sandbox/linux/seccomp-bpf-helpers/sigsys_handlers.h index 7a958b93b..d0bfab74b 100644 --- a/sandbox/linux/seccomp-bpf-helpers/sigsys_handlers.h +++ b/sandbox/linux/seccomp-bpf-helpers/sigsys_handlers.h @@ -62,6 +62,10 @@ SANDBOX_EXPORT intptr_t SIGSYSPtraceFailure(const arch_seccomp_data& args, // 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 CrashSIGSYSKill(); 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 --git a/sandbox/linux/services/syscall_wrappers.cc b/sandbox/linux/services/syscall_wrappers.cc index fcfd2aa12..5396b36da 100644 --- a/sandbox/linux/services/syscall_wrappers.cc +++ b/sandbox/linux/services/syscall_wrappers.cc @@ -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 --git a/sandbox/linux/services/syscall_wrappers.h b/sandbox/linux/services/syscall_wrappers.h index 1975bfbd8..ed7ee5a1c 100644 --- a/sandbox/linux/services/syscall_wrappers.h +++ b/sandbox/linux/services/syscall_wrappers.h @@ -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 signum, 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_