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i#907 early inject symlink: replace accesses to /proc/self/exe
For early injection, /proc/self/exe points at libdynamorio.so instead of the app. We monitor SYS_readlink and SYS_execve and when we see a reference to the /proc/self/exe for this process we replace it with the actual application path. Adds a new linux.readlink test. Fixes #907 Review-URL: https://codereview.appspot.com/211650043
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,82 @@ | ||
| /* ********************************************************** | ||
| * Copyright (c) 2015 Google, Inc. All rights reserved. | ||
| * **********************************************************/ | ||
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| /* | ||
| * Redistribution and use in source and binary forms, with or without | ||
| * modification, are permitted provided that the following conditions are met: | ||
| * | ||
| * * Redistributions of source code must retain the above copyright notice, | ||
| * this list of conditions and the following disclaimer. | ||
| * | ||
| * * Redistributions in binary form must reproduce the above copyright notice, | ||
| * this list of conditions and the following disclaimer in the documentation | ||
| * and/or other materials provided with the distribution. | ||
| * | ||
| * * Neither the name of VMware, Inc. nor the names of its contributors may be | ||
| * used to endorse or promote products derived from this software without | ||
| * specific prior written permission. | ||
| * | ||
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" | ||
| * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | ||
| * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | ||
| * ARE DISCLAIMED. IN NO EVENT SHALL VMWARE, INC. OR CONTRIBUTORS BE LIABLE | ||
| * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | ||
| * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR | ||
| * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER | ||
| * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | ||
| * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY | ||
| * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH | ||
| * DAMAGE. | ||
| */ | ||
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| #include "tools.h" | ||
| #include <unistd.h> | ||
| #include <stdio.h> | ||
| #include <sys/types.h> | ||
| #include <sys/wait.h> | ||
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| /* Tests i#907: /proc/self/exe transparency with early injection. */ | ||
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| int | ||
| main(int argc, char *argv[]) | ||
| { | ||
| /* Test reading the symlink via readlink */ | ||
| char proc[64]; | ||
| char buf[512]; | ||
| ssize_t res; | ||
| snprintf(proc, BUFFER_SIZE_ELEMENTS(proc), "/proc/%d/exe", getpid()); | ||
| NULL_TERMINATE_BUFFER(proc); | ||
| res = readlink(proc, buf, BUFFER_SIZE_ELEMENTS(buf)); | ||
| NULL_TERMINATE_BUFFER(buf); | ||
| if (res > 0 && strrchr(buf, '/') != NULL) | ||
| print("/proc/pid/exe points to %s\n", strrchr(buf, '/')+1); | ||
| else { | ||
| perror("readlink failed"); | ||
| return 1; | ||
| } | ||
| /* XXX: another good test would be to make a thread and use /proc/tid/exe */ | ||
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| /* Test executing the symlink via execve. | ||
| * We invoked ourselves initially with an arg, to avoid repeated execs. | ||
| */ | ||
| if (argc > 1) { | ||
| pid_t child = fork(); | ||
| if (child < 0) { | ||
| perror("fork failed"); | ||
| } else if (child > 0) { | ||
| pid_t result = waitpid(child, NULL, 0); | ||
| assert(result == child); | ||
| print("child has exited\n"); | ||
| } else { | ||
| const char *arg[2] = {proc, NULL}; | ||
| /* Update for child's pid */ | ||
| snprintf(proc, BUFFER_SIZE_ELEMENTS(proc), "/proc/%d/exe", getpid()); | ||
| NULL_TERMINATE_BUFFER(proc); | ||
| res = execve(proc, (char **)arg, NULL/*env*/); | ||
| if (res < 0) | ||
| perror("execve failed"); | ||
| } | ||
| } | ||
| return 0; | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,3 @@ | ||
| /proc/pid/exe points to linux.readlink | ||
| /proc/pid/exe points to linux.readlink | ||
| child has exited |