1 // Copyright 2014 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #include "sandbox/linux/services/syscall_wrappers.h"
6
7 #include <pthread.h>
8 #include <sched.h>
9 #include <setjmp.h>
10 #include <sys/resource.h>
11 #include <sys/syscall.h>
12 #include <sys/time.h>
13 #include <sys/types.h>
14 #include <unistd.h>
15 #include <cstring>
16
17 #include "base/compiler_specific.h"
18 #include "base/logging.h"
19 #include "build/build_config.h"
20 #include "sandbox/linux/system_headers/capability.h"
21 #include "sandbox/linux/system_headers/linux_signal.h"
22 #include "sandbox/linux/system_headers/linux_syscalls.h"
23 #include "third_party/valgrind/valgrind.h"
24
25 namespace sandbox {
26
sys_getpid(void)27 pid_t sys_getpid(void) {
28 return syscall(__NR_getpid);
29 }
30
sys_gettid(void)31 pid_t sys_gettid(void) {
32 return syscall(__NR_gettid);
33 }
34
sys_clone(unsigned long flags,std::nullptr_t child_stack,pid_t * ptid,pid_t * ctid,std::nullptr_t tls)35 long sys_clone(unsigned long flags,
36 std::nullptr_t child_stack,
37 pid_t* ptid,
38 pid_t* ctid,
39 std::nullptr_t tls) {
40 const bool clone_tls_used = flags & CLONE_SETTLS;
41 const bool invalid_ctid =
42 (flags & (CLONE_CHILD_SETTID | CLONE_CHILD_CLEARTID)) && !ctid;
43 const bool invalid_ptid = (flags & CLONE_PARENT_SETTID) && !ptid;
44
45 // We do not support CLONE_VM.
46 const bool clone_vm_used = flags & CLONE_VM;
47 if (clone_tls_used || invalid_ctid || invalid_ptid || clone_vm_used) {
48 RAW_LOG(FATAL, "Invalid usage of sys_clone");
49 }
50
51 if (ptid) MSAN_UNPOISON(ptid, sizeof(*ptid));
52 if (ctid) MSAN_UNPOISON(ctid, sizeof(*ctid));
53 // See kernel/fork.c in Linux. There is different ordering of sys_clone
54 // parameters depending on CONFIG_CLONE_BACKWARDS* configuration options.
55 #if defined(ARCH_CPU_X86_64)
56 return syscall(__NR_clone, flags, child_stack, ptid, ctid, tls);
57 #elif defined(ARCH_CPU_X86) || defined(ARCH_CPU_ARM_FAMILY) || \
58 defined(ARCH_CPU_MIPS_FAMILY) || defined(ARCH_CPU_MIPS64_FAMILY)
59 // CONFIG_CLONE_BACKWARDS defined.
60 return syscall(__NR_clone, flags, child_stack, ptid, tls, ctid);
61 #endif
62 }
63
sys_clone(unsigned long flags)64 long sys_clone(unsigned long flags) {
65 return sys_clone(flags, nullptr, nullptr, nullptr, nullptr);
66 }
67
sys_exit_group(int status)68 void sys_exit_group(int status) {
69 syscall(__NR_exit_group, status);
70 }
71
sys_seccomp(unsigned int operation,unsigned int flags,const struct sock_fprog * args)72 int sys_seccomp(unsigned int operation,
73 unsigned int flags,
74 const struct sock_fprog* args) {
75 return syscall(__NR_seccomp, operation, flags, args);
76 }
77
sys_prlimit64(pid_t pid,int resource,const struct rlimit64 * new_limit,struct rlimit64 * old_limit)78 int sys_prlimit64(pid_t pid,
79 int resource,
80 const struct rlimit64* new_limit,
81 struct rlimit64* old_limit) {
82 int res = syscall(__NR_prlimit64, pid, resource, new_limit, old_limit);
83 if (res == 0 && old_limit) MSAN_UNPOISON(old_limit, sizeof(*old_limit));
84 return res;
85 }
86
sys_capget(cap_hdr * hdrp,cap_data * datap)87 int sys_capget(cap_hdr* hdrp, cap_data* datap) {
88 int res = syscall(__NR_capget, hdrp, datap);
89 if (res == 0) {
90 if (hdrp) MSAN_UNPOISON(hdrp, sizeof(*hdrp));
91 if (datap) MSAN_UNPOISON(datap, sizeof(*datap));
92 }
93 return res;
94 }
95
sys_capset(cap_hdr * hdrp,const cap_data * datap)96 int sys_capset(cap_hdr* hdrp, const cap_data* datap) {
97 return syscall(__NR_capset, hdrp, datap);
98 }
99
sys_getresuid(uid_t * ruid,uid_t * euid,uid_t * suid)100 int sys_getresuid(uid_t* ruid, uid_t* euid, uid_t* suid) {
101 int res;
102 #if defined(ARCH_CPU_X86) || defined(ARCH_CPU_ARMEL)
103 // On 32-bit x86 or 32-bit arm, getresuid supports 16bit values only.
104 // Use getresuid32 instead.
105 res = syscall(__NR_getresuid32, ruid, euid, suid);
106 #else
107 res = syscall(__NR_getresuid, ruid, euid, suid);
108 #endif
109 if (res == 0) {
110 if (ruid) MSAN_UNPOISON(ruid, sizeof(*ruid));
111 if (euid) MSAN_UNPOISON(euid, sizeof(*euid));
112 if (suid) MSAN_UNPOISON(suid, sizeof(*suid));
113 }
114 return res;
115 }
116
sys_getresgid(gid_t * rgid,gid_t * egid,gid_t * sgid)117 int sys_getresgid(gid_t* rgid, gid_t* egid, gid_t* sgid) {
118 int res;
119 #if defined(ARCH_CPU_X86) || defined(ARCH_CPU_ARMEL)
120 // On 32-bit x86 or 32-bit arm, getresgid supports 16bit values only.
121 // Use getresgid32 instead.
122 res = syscall(__NR_getresgid32, rgid, egid, sgid);
123 #else
124 res = syscall(__NR_getresgid, rgid, egid, sgid);
125 #endif
126 if (res == 0) {
127 if (rgid) MSAN_UNPOISON(rgid, sizeof(*rgid));
128 if (egid) MSAN_UNPOISON(egid, sizeof(*egid));
129 if (sgid) MSAN_UNPOISON(sgid, sizeof(*sgid));
130 }
131 return res;
132 }
133
sys_chroot(const char * path)134 int sys_chroot(const char* path) {
135 return syscall(__NR_chroot, path);
136 }
137
sys_unshare(int flags)138 int sys_unshare(int flags) {
139 return syscall(__NR_unshare, flags);
140 }
141
sys_sigprocmask(int how,const sigset_t * set,std::nullptr_t oldset)142 int sys_sigprocmask(int how, const sigset_t* set, std::nullptr_t oldset) {
143 // In some toolchain (in particular Android and PNaCl toolchain),
144 // sigset_t is 32 bits, but the Linux ABI uses more.
145 LinuxSigSet linux_value;
146 std::memset(&linux_value, 0, sizeof(LinuxSigSet));
147 std::memcpy(&linux_value, set, std::min(sizeof(sigset_t),
148 sizeof(LinuxSigSet)));
149
150 return syscall(__NR_rt_sigprocmask, how, &linux_value, nullptr,
151 sizeof(linux_value));
152 }
153
154 // When this is built with PNaCl toolchain, we should always use sys_sigaction
155 // below, because sigaction() provided by the toolchain is incompatible with
156 // Linux's ABI.
157 #if !defined(OS_NACL_NONSFI)
sys_sigaction(int signum,const struct sigaction * act,struct sigaction * oldact)158 int sys_sigaction(int signum,
159 const struct sigaction* act,
160 struct sigaction* oldact) {
161 return sigaction(signum, act, oldact);
162 }
163 #else
164 #if defined(ARCH_CPU_X86_FAMILY)
165
166 // On x86_64, sa_restorer is required. We specify it on x86 as well in order to
167 // support kernels with VDSO disabled.
168 #if !defined(SA_RESTORER)
169 #define SA_RESTORER 0x04000000
170 #endif
171
172 // XSTR(__NR_foo) expands to a string literal containing the value value of
173 // __NR_foo.
174 #define STR(x) #x
175 #define XSTR(x) STR(x)
176
177 // rt_sigreturn is a special system call that interacts with the user land
178 // stack. Thus, here prologue must not be created, which implies syscall()
179 // does not work properly, too. Note that rt_sigreturn does not return.
180 // TODO(rickyz): These assembly functions may still break stack unwinding on
181 // nonsfi NaCl builds.
182 #if defined(ARCH_CPU_X86_64)
183
184 extern "C" {
185 void sys_rt_sigreturn();
186 }
187
188 asm(
189 ".text\n"
190 "sys_rt_sigreturn:\n"
191 "mov $" XSTR(__NR_rt_sigreturn) ", %eax\n"
192 "syscall\n");
193
194 #elif defined(ARCH_CPU_X86)
195 extern "C" {
196 void sys_sigreturn();
197 void sys_rt_sigreturn();
198 }
199
200 asm(
201 ".text\n"
202 "sys_rt_sigreturn:\n"
203 "mov $" XSTR(__NR_rt_sigreturn) ", %eax\n"
204 "int $0x80\n"
205
206 "sys_sigreturn:\n"
207 "pop %eax\n"
208 "mov $" XSTR(__NR_sigreturn) ", %eax\n"
209 "int $0x80\n");
210 #else
211 #error "Unsupported architecture."
212 #endif
213
214 #undef STR
215 #undef XSTR
216
217 #endif
218
sys_sigaction(int signum,const struct sigaction * act,struct sigaction * oldact)219 int sys_sigaction(int signum,
220 const struct sigaction* act,
221 struct sigaction* oldact) {
222 LinuxSigAction linux_act = {};
223 if (act) {
224 linux_act.kernel_handler = act->sa_handler;
225 std::memcpy(&linux_act.sa_mask, &act->sa_mask,
226 std::min(sizeof(linux_act.sa_mask), sizeof(act->sa_mask)));
227 linux_act.sa_flags = act->sa_flags;
228
229 #if defined(ARCH_CPU_X86_FAMILY)
230 if (!(linux_act.sa_flags & SA_RESTORER)) {
231 linux_act.sa_flags |= SA_RESTORER;
232 #if defined(ARCH_CPU_X86_64)
233 linux_act.sa_restorer = sys_rt_sigreturn;
234 #elif defined(ARCH_CPU_X86)
235 linux_act.sa_restorer =
236 linux_act.sa_flags & SA_SIGINFO ? sys_rt_sigreturn : sys_sigreturn;
237 #else
238 #error "Unsupported architecture."
239 #endif
240 }
241 #endif
242 }
243
244 LinuxSigAction linux_oldact = {};
245 int result = syscall(__NR_rt_sigaction, signum, act ? &linux_act : nullptr,
246 oldact ? &linux_oldact : nullptr,
247 sizeof(LinuxSigSet));
248
249 if (result == 0 && oldact) {
250 oldact->sa_handler = linux_oldact.kernel_handler;
251 sigemptyset(&oldact->sa_mask);
252 std::memcpy(&oldact->sa_mask, &linux_oldact.sa_mask,
253 std::min(sizeof(linux_act.sa_mask), sizeof(act->sa_mask)));
254 oldact->sa_flags = linux_oldact.sa_flags;
255 }
256 return result;
257 }
258
259 #endif // defined(MEMORY_SANITIZER)
260
261 } // namespace sandbox
262