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EtiennePerotgvisor-bot
EtiennePerot
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Implement personality(2) for no-op personality bits.
This PR implements the [`personality(2)` syscall](https://www.man7.org/linux/man-pages/man2/personality.2.html) for personality bits that are no-ops on Linux. Fixes #10756. FUTURE_COPYBARA_INTEGRATE_REVIEW=#10757 from EtiennePerot:linux-is-not-a-personality-trait 91d3665 PiperOrigin-RevId: 665427818
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12 files changed

+277
-2
lines changed

12 files changed

+277
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lines changed

‎pkg/abi/linux/BUILD

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@@ -58,6 +58,7 @@ go_library(
5858
"netlink.go",
5959
"netlink_route.go",
6060
"nf_tables.go",
61+
"personality.go",
6162
"poll.go",
6263
"prctl.go",
6364
"ptrace.go",

‎pkg/abi/linux/personality.go

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@@ -0,0 +1,29 @@
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// Copyright 2024 The gVisor Authors.
2+
//
3+
// Licensed under the Apache License, Version 2.0 (the "License");
4+
// you may not use this file except in compliance with the License.
5+
// You may obtain a copy of the License at
6+
//
7+
// http://www.apache.org/licenses/LICENSE-2.0
8+
//
9+
// Unless required by applicable law or agreed to in writing, software
10+
// distributed under the License is distributed on an "AS IS" BASIS,
11+
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12+
// See the License for the specific language governing permissions and
13+
// limitations under the License.
14+
15+
package linux
16+
17+
// Personality flags, used by personality(2),
18+
// from include/uapi/linux/personality.h.
19+
const (
20+
SHORT_INODE = 0x1000000
21+
WHOLE_SECONDS = 0x2000000
22+
PER_LINUX = 0x0000
23+
PER_BSD = 0x0006
24+
)
25+
26+
// NOTE: All of the above flags are non-security-sensitive and may be copied
27+
// from parent task to child task. However, this is not the case for all
28+
// personality bits. If adding more, check PER_CLEAR_ON_SETID and ensure that
29+
// these are cleared on suid/sgid execs.

‎pkg/sentry/kernel/kernel.go

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@@ -1157,6 +1157,7 @@ func (k *Kernel) CreateProcess(args CreateProcessArgs) (*ThreadGroup, ThreadID,
11571157
InitialCgroups: args.InitialCgroups,
11581158
UserCounters: k.GetUserCounters(args.Credentials.RealKUID),
11591159
Origin: args.Origin,
1160+
Personality: linux.PER_LINUX,
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// A task with no parent starts out with no session keyring.
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SessionKeyring: nil,
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}

‎pkg/sentry/kernel/task.go

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@@ -608,6 +608,9 @@ type Task struct {
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// +checklocks:mu
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sessionKeyring *auth.Key
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// personality is the task's personality(2) bits.
612+
personality atomicbitops.Uint32
613+
611614
// Origin is the origin of the task.
612615
Origin TaskOrigin
613616
}
@@ -869,3 +872,14 @@ func (t *Task) ResetKcov() {
869872
t.kcov = nil
870873
}
871874
}
875+
876+
// Personality returns the task's personality.
877+
func (t *Task) Personality() uint32 {
878+
return t.personality.Load()
879+
}
880+
881+
// SetPersonality sets the task's personality.
882+
// It returns the task's former personality.
883+
func (t *Task) SetPersonality(personality uint32) uint32 {
884+
return t.personality.Swap(personality)
885+
}

‎pkg/sentry/kernel/task_clone.go

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@@ -265,6 +265,7 @@ func (t *Task) Clone(args *linux.CloneArgs) (ThreadID, *SyscallControl, error) {
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ContainerID: t.ContainerID(),
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UserCounters: uc,
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SessionKeyring: sessionKeyring,
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Personality: t.personality.Load(),
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Origin: t.Origin,
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}
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if args.Flags&linux.CLONE_THREAD == 0 {

‎pkg/sentry/kernel/task_start.go

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@@ -104,6 +104,9 @@ type TaskConfig struct {
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// It may be nil.
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SessionKeyring *auth.Key
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// Personality is the personality of the parent task.
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Personality uint32
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Origin TaskOrigin
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}
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@@ -174,6 +177,7 @@ func (ts *TaskSet) newTask(ctx context.Context, cfg *TaskConfig) (*Task, error)
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cgroups: make(map[Cgroup]struct{}),
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userCounters: cfg.UserCounters,
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sessionKeyring: cfg.SessionKeyring,
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personality: atomicbitops.FromUint32(cfg.Personality),
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Origin: cfg.Origin,
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}
179183
t.netns = cfg.NetworkNamespace

‎pkg/sentry/syscalls/linux/BUILD

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@@ -33,6 +33,7 @@ go_library(
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"sys_mount.go",
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"sys_mq.go",
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"sys_msgqueue.go",
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"sys_personality.go",
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"sys_pipe.go",
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"sys_poll.go",
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"sys_prctl.go",

‎pkg/sentry/syscalls/linux/linux64.go

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@@ -187,7 +187,7 @@ var AMD64 = &kernel.SyscallTable{
187187
132: syscalls.Supported("utime", Utime),
188188
133: syscalls.Supported("mknod", Mknod),
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134: syscalls.Error("uselib", linuxerr.ENOSYS, "Obsolete", nil),
190-
135: syscalls.ErrorWithEvent("personality", linuxerr.EINVAL, "Unable to change personality.", nil),
190+
135: syscalls.PartiallySupported("personality", Personality, "Only setting no-op personality bits and retrieving them are supported.", nil),
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136: syscalls.ErrorWithEvent("ustat", linuxerr.ENOSYS, "Needs filesystem support.", nil),
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137: syscalls.Supported("statfs", Statfs),
193193
138: syscalls.Supported("fstatfs", Fstatfs),
@@ -523,7 +523,7 @@ var ARM64 = &kernel.SyscallTable{
523523
89: syscalls.CapError("acct", linux.CAP_SYS_PACCT, "", nil),
524524
90: syscalls.Supported("capget", Capget),
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91: syscalls.Supported("capset", Capset),
526-
92: syscalls.ErrorWithEvent("personality", linuxerr.EINVAL, "Unable to change personality.", nil),
526+
92: syscalls.PartiallySupported("personality", Personality, "Only setting no-op personality bits and retrieving them are supported.", nil),
527527
93: syscalls.Supported("exit", Exit),
528528
94: syscalls.Supported("exit_group", ExitGroup),
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95: syscalls.Supported("waitid", Waitid),

‎pkg/sentry/syscalls/linux/sys_personality.go

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@@ -0,0 +1,43 @@
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// Copyright 2024 The gVisor Authors.
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//
3+
// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
5+
// You may obtain a copy of the License at
6+
//
7+
// http://www.apache.org/licenses/LICENSE-2.0
8+
//
9+
// Unless required by applicable law or agreed to in writing, software
10+
// distributed under the License is distributed on an "AS IS" BASIS,
11+
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12+
// See the License for the specific language governing permissions and
13+
// limitations under the License.
14+
15+
package linux
16+
17+
import (
18+
"gvisor.dev/gvisor/pkg/abi/linux"
19+
"gvisor.dev/gvisor/pkg/errors/linuxerr"
20+
"gvisor.dev/gvisor/pkg/sentry/arch"
21+
"gvisor.dev/gvisor/pkg/sentry/kernel"
22+
)
23+
24+
const (
25+
// getPersonality may be passed to `personality(2)` to get the current
26+
// personality bits without modifying them.
27+
getPersonality = 0xffffffff
28+
)
29+
30+
// Personality implements Linux syscall personality(2).
31+
func Personality(t *kernel.Task, sysno uintptr, args arch.SyscallArguments) (uintptr, *kernel.SyscallControl, error) {
32+
// allowedPersonalityBits are the personality bits that are allowed to be set.
33+
const allowedPersonalityBits = linux.PER_LINUX | linux.PER_BSD | linux.SHORT_INODE | linux.WHOLE_SECONDS
34+
35+
personality := args[0].Uint()
36+
if personality == getPersonality {
37+
return uintptr(t.Personality()), nil, nil
38+
}
39+
if personality&allowedPersonalityBits != personality {
40+
return 0, nil, linuxerr.EINVAL
41+
}
42+
return uintptr(t.SetPersonality(personality)), nil, nil
43+
}

‎test/syscalls/BUILD

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@@ -479,6 +479,10 @@ syscall_test(
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test = "//test/syscalls/linux:pause_test",
480480
)
481481

482+
syscall_test(
483+
test = "//test/syscalls/linux:personality_test",
484+
)
485+
482486
syscall_test(
483487
size = "medium",
484488
add_hostinet = True,

‎test/syscalls/linux/BUILD

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@@ -1670,6 +1670,20 @@ cc_binary(
16701670
],
16711671
)
16721672

1673+
cc_binary(
1674+
name = "personality_test",
1675+
testonly = 1,
1676+
srcs = ["personality.cc"],
1677+
linkstatic = 1,
1678+
malloc = "//test/util:errno_safe_allocator",
1679+
deps = select_gtest() + [
1680+
"//test/util:multiprocess_util",
1681+
"//test/util:posix_error",
1682+
"//test/util:test_main",
1683+
"//test/util:test_util",
1684+
],
1685+
)
1686+
16731687
cc_binary(
16741688
name = "ping_socket_test",
16751689
testonly = 1,

‎test/syscalls/linux/personality.cc

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@@ -0,0 +1,163 @@
1+
// Copyright 2024 The gVisor Authors.
2+
//
3+
// Licensed under the Apache License, Version 2.0 (the "License");
4+
// you may not use this file except in compliance with the License.
5+
// You may obtain a copy of the License at
6+
//
7+
// http://www.apache.org/licenses/LICENSE-2.0
8+
//
9+
// Unless required by applicable law or agreed to in writing, software
10+
// distributed under the License is distributed on an "AS IS" BASIS,
11+
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12+
// See the License for the specific language governing permissions and
13+
// limitations under the License.
14+
15+
#include <sys/personality.h>
16+
17+
#include "gtest/gtest.h"
18+
#include "test/util/multiprocess_util.h"
19+
#include "test/util/posix_error.h"
20+
#include "test/util/test_util.h"
21+
22+
namespace gvisor {
23+
namespace testing {
24+
25+
namespace {
26+
27+
constexpr uint64_t kGetPersonality = 0xffffffff;
28+
constexpr uint64_t kUndefinedPersonalityBit = 0x00001000;
29+
30+
TEST(PersonalityTest, DefaultPersonality) {
31+
EXPECT_THAT(personality(kGetPersonality),
32+
SyscallSucceedsWithValue(PER_LINUX));
33+
}
34+
35+
TEST(PersonalityTest, SetLinux) {
36+
EXPECT_THAT(personality(kGetPersonality),
37+
SyscallSucceedsWithValue(PER_LINUX));
38+
EXPECT_THAT(InForkedProcess([&] {
39+
TEST_CHECK(personality(PER_LINUX) == PER_LINUX);
40+
TEST_CHECK(personality(kGetPersonality) == PER_LINUX);
41+
TEST_CHECK(personality(kGetPersonality) == PER_LINUX);
42+
}),
43+
IsPosixErrorOkAndHolds(0));
44+
EXPECT_THAT(personality(kGetPersonality),
45+
SyscallSucceedsWithValue(PER_LINUX));
46+
}
47+
48+
TEST(PersonalityTest, SetBSD) {
49+
EXPECT_THAT(personality(kGetPersonality),
50+
SyscallSucceedsWithValue(PER_LINUX));
51+
EXPECT_THAT(InForkedProcess([&] {
52+
TEST_CHECK(personality(PER_BSD) == PER_LINUX);
53+
TEST_CHECK(personality(kGetPersonality) == PER_BSD);
54+
}),
55+
IsPosixErrorOkAndHolds(0));
56+
}
57+
58+
TEST(PersonalityTest, PersonalityIsInheritable) {
59+
EXPECT_THAT(
60+
InForkedProcess([&] {
61+
TEST_CHECK(personality(PER_BSD) == PER_LINUX);
62+
TEST_CHECK(personality(kGetPersonality) == PER_BSD);
63+
TEST_CHECK(
64+
InForkedProcess([&] {
65+
TEST_CHECK(personality(kGetPersonality) == PER_BSD);
66+
TEST_CHECK(InForkedProcess([&] {
67+
TEST_CHECK(personality(kGetPersonality) == PER_BSD);
68+
}).ok());
69+
TEST_CHECK(personality(PER_SOLARIS) == PER_BSD);
70+
TEST_CHECK(InForkedProcess([&] {
71+
TEST_CHECK(personality(kGetPersonality) ==
72+
PER_SOLARIS);
73+
}).ok());
74+
TEST_CHECK(personality(PER_BSD) == PER_SOLARIS);
75+
TEST_CHECK(InForkedProcess([&] {
76+
TEST_CHECK(personality(kGetPersonality) == PER_BSD);
77+
}).ok());
78+
TEST_CHECK(personality(kGetPersonality) == PER_BSD);
79+
}).ok());
80+
}),
81+
IsPosixErrorOkAndHolds(0));
82+
}
83+
84+
TEST(PersonalityTest, ChildPersonalityDoesNotAffectParent) {
85+
EXPECT_THAT(
86+
InForkedProcess([&] {
87+
TEST_CHECK(personality(PER_BSD) == PER_LINUX);
88+
TEST_CHECK(personality(kGetPersonality) == PER_BSD);
89+
TEST_CHECK(InForkedProcess([&] {
90+
TEST_CHECK(personality(PER_SOLARIS) == PER_BSD);
91+
TEST_CHECK(personality(kGetPersonality) == PER_SOLARIS);
92+
}).ok());
93+
TEST_CHECK(personality(kGetPersonality) == PER_BSD);
94+
}),
95+
IsPosixErrorOkAndHolds(0));
96+
TEST_CHECK(personality(kGetPersonality) == PER_LINUX);
97+
}
98+
99+
TEST(PersonalityTest, SetShortInode) {
100+
EXPECT_THAT(InForkedProcess([&] {
101+
TEST_CHECK(personality(SHORT_INODE) == PER_LINUX);
102+
TEST_CHECK(personality(kGetPersonality) == SHORT_INODE);
103+
}),
104+
IsPosixErrorOkAndHolds(0));
105+
}
106+
107+
TEST(PersonalityTest, SetWholeSeconds) {
108+
EXPECT_THAT(InForkedProcess([&] {
109+
TEST_CHECK(personality(WHOLE_SECONDS) == PER_LINUX);
110+
TEST_CHECK(personality(kGetPersonality) == WHOLE_SECONDS);
111+
}),
112+
IsPosixErrorOkAndHolds(0));
113+
}
114+
115+
TEST(PersonalityTest, SetMultiple) {
116+
EXPECT_THAT(InForkedProcess([&] {
117+
TEST_CHECK(personality(PER_BSD | SHORT_INODE | WHOLE_SECONDS) ==
118+
PER_LINUX);
119+
TEST_CHECK(personality(kGetPersonality) ==
120+
(PER_BSD | SHORT_INODE | WHOLE_SECONDS));
121+
}),
122+
IsPosixErrorOkAndHolds(0));
123+
}
124+
125+
TEST(PersonalityTest, SetThenUnset) {
126+
EXPECT_THAT(
127+
InForkedProcess([&] {
128+
TEST_CHECK(personality(PER_BSD | SHORT_INODE) == PER_LINUX);
129+
TEST_CHECK(personality(WHOLE_SECONDS | SHORT_INODE) ==
130+
(PER_BSD | SHORT_INODE));
131+
TEST_CHECK(personality(PER_BSD) == (WHOLE_SECONDS | SHORT_INODE));
132+
TEST_CHECK(personality(kGetPersonality) == PER_BSD);
133+
}),
134+
IsPosixErrorOkAndHolds(0));
135+
}
136+
137+
TEST(PersonalityTest, UnsupportedPersonalityBitsAreRejected) {
138+
SKIP_IF(!IsRunningOnGvisor());
139+
EXPECT_THAT(personality(kGetPersonality),
140+
SyscallSucceedsWithValue(PER_LINUX));
141+
EXPECT_THAT(personality(MMAP_PAGE_ZERO), SyscallFailsWithErrno(EINVAL));
142+
EXPECT_THAT(personality(ADDR_LIMIT_3GB), SyscallFailsWithErrno(EINVAL));
143+
EXPECT_THAT(personality(ADDR_LIMIT_32BIT), SyscallFailsWithErrno(EINVAL));
144+
EXPECT_THAT(personality(ADDR_NO_RANDOMIZE), SyscallFailsWithErrno(EINVAL));
145+
EXPECT_THAT(personality(ADDR_COMPAT_LAYOUT), SyscallFailsWithErrno(EINVAL));
146+
EXPECT_THAT(personality(READ_IMPLIES_EXEC), SyscallFailsWithErrno(EINVAL));
147+
EXPECT_THAT(personality(STICKY_TIMEOUTS), SyscallFailsWithErrno(EINVAL));
148+
EXPECT_THAT(personality(UNAME26), SyscallFailsWithErrno(EINVAL));
149+
EXPECT_THAT(personality(FDPIC_FUNCPTRS), SyscallFailsWithErrno(EINVAL));
150+
EXPECT_THAT(personality(PER_LINUX32), SyscallFailsWithErrno(EINVAL));
151+
EXPECT_THAT(personality(PER_LINUX32_3GB), SyscallFailsWithErrno(EINVAL));
152+
EXPECT_THAT(personality(PER_LINUX_32BIT), SyscallFailsWithErrno(EINVAL));
153+
EXPECT_THAT(personality(PER_LINUX_FDPIC), SyscallFailsWithErrno(EINVAL));
154+
EXPECT_THAT(personality(PER_RISCOS), SyscallFailsWithErrno(EINVAL));
155+
EXPECT_THAT(personality(PER_SOLARIS), SyscallFailsWithErrno(EINVAL));
156+
EXPECT_THAT(personality(kGetPersonality),
157+
SyscallSucceedsWithValue(PER_LINUX));
158+
}
159+
160+
} // namespace
161+
162+
} // namespace testing
163+
} // namespace gvisor

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