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92 lines
2.1 KiB
92 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-arm.S"
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.thumb
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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 r7, SYS_MPROTECT
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adr r0, context
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movw r2, 0xF000
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movt r2, 0xFFFF
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and r0, r0, r2
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mov r1, 0x2000
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mov r2, (PROT_READ | PROT_EXEC)
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swi 0
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// r10 = open("/proc/self/attr/current", O_WRONLY, O_WRONLY)
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mov r7, SYS_OPEN
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adr r0, selinux_proc_file
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mov r1, O_WRONLY
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mov r2, O_WRONLY
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swi 0
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mov r10, r0
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// r11 = strlen(context)
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mov r11, 0
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adr r0, context
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strlen_start:
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ldrb r1, [r0, r11]
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cmp r1, 0
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beq strlen_done
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add r11, r11, 1
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b strlen_start
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strlen_done:
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// write(r10, context, r11)
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mov r7, SYS_WRITE
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mov r0, r10
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adr r1, context
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mov r2, r11
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swi 0
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// close(r10)
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mov r7, SYS_CLOSE
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mov r0, r10
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swi 0
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// r0 = getpid()
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mov r7, SYS_GETPID
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swi 0
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// kill(r0, SIGSTOP)
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mov r7, SYS_KILL
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mov r1, SIGSTOP
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swi 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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