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89 lines
2.1 KiB
89 lines
2.1 KiB
/*
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* Copyright (C) 2023 The Android Open Source Project
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*
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* 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.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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// Shell code that sets the current SELinux context to a given string.
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//
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// The desired SELinux context is appended to the payload as a null-terminated
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// string.
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//
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// After the SELinux context has been updated the current process will raise
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// SIGSTOP.
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#include "./shell-code/constants.S"
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#include "./shell-code/constants-arm64.S"
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.globl __setcon_shell_code_start
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.globl __setcon_shell_code_end
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__setcon_shell_code_start:
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// Ensure that the context and SELinux /proc file are readable. This assumes
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// that the max length of these two strings is shorter than 0x1000.
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//
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// mprotect(context & ~0xFFF, 0x2000, PROT_READ | PROT_EXEC)
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mov x8, SYS_MPROTECT
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adr X0, __setcon_shell_code_end
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and x0, x0, ~0xFFF
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mov x1, 0x2000
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mov x2, (PROT_READ | PROT_EXEC)
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svc 0
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// x10 = openat(AT_FDCWD, "/proc/self/attr/current", O_WRONLY, O_WRONLY)
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mov x8, SYS_OPENAT
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mov x0, AT_FDCWD
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adr x1, selinux_proc_file
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mov x2, O_WRONLY
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mov x3, O_WRONLY
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svc 0
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mov x10, x0
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// x11 = strlen(context)
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mov x11, 0
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adr x0, context
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strlen_start:
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ldrb w1, [x0, x11]
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cmp w1, 0
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b.eq strlen_done
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add x11, x11, 1
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b strlen_start
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strlen_done:
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// write(x10, context, x11)
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mov x8, SYS_WRITE
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mov x0, x10
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adr x1, context
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mov x2, x11
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svc 0
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// close(x10)
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mov x8, SYS_CLOSE
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mov x0, x10
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svc 0
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// x0 = getpid()
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mov x8, SYS_GETPID
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svc 0
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// kill(x0, SIGSTOP)
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mov x8, SYS_KILL
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mov x1, SIGSTOP
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svc 0
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selinux_proc_file:
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.asciz "/proc/thread-self/attr/current"
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context:
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__setcon_shell_code_end:
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