this repo has no description
Remove capabities and libcap dependency
See the darlingserver commit for more details.
+67
-63
-4
src/startup/mldr/CMakeLists.txt
-4
src/startup/mldr/CMakeLists.txt
···
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target_link_libraries(mldr PRIVATE -lrt -ldl mldr_dserver_rpc)
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include(setcap)
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install(TARGETS mldr DESTINATION libexec/darling/usr/libexec/darling)
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setcap(libexec/darling/usr/libexec/darling/mldr cap_sys_rawio,cap_sys_resource+ep)
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configure_file(darling.conf.in darling.conf @ONLY)
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install(FILES "${CMAKE_CURRENT_BINARY_DIR}/darling.conf" DESTINATION lib/binfmt.d)
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target_link_libraries(mldr32 PRIVATE -lrt -ldl mldr32_dserver_rpc)
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install(TARGETS mldr32 DESTINATION libexec/darling/usr/libexec/darling)
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setcap(libexec/darling/usr/libexec/darling/mldr32 cap_sys_rawio,cap_sys_resource+ep)
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endif()
+67
-6
src/startup/mldr/mldr.c
+67
-6
src/startup/mldr/mldr.c
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#include <sys/socket.h>
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#include <sys/un.h>
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#include <darlingserver/rpc.h>
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#include <sys/ptrace.h>
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#ifndef PAGE_SIZE
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# define PAGE_SIZE 4096
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static uint32_t stack_size = 0;
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static const char* const skip_env_vars[] = {
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"__mldr_bprefs=",
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"__mldr_sockpath=",
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};
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int main(int argc, char** argv, char** envp)
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{
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void** sp;
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int pushCount = 0;
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char *filename, *p = NULL;
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size_t arg_strings_total_size_after = 0;
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size_t orig_argv0_len = 0;
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const char* orig_argv1 = NULL;
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mldr_load_results.kernfd = -1;
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mldr_load_results.argc = argc;
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strcpy(filename, argv[1]);
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}
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// allow any process to ptrace us
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// the only process we really care about being able to do this is the server,
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// but we can't just use the server's PID, since it lies outside our PID namespace.
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ptrace(PR_SET_PTRACER, PR_SET_PTRACER_ANY, 0, 0, 0);
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process_special_env(&mldr_load_results);
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#ifdef __i386__
···
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}
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#endif
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if (prctl(PR_SET_MM, PR_SET_MM_START_STACK, mldr_load_results.stack_top, 0, 0) < 0) {
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fprintf(stderr, "Failed to set stack start\n");
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return 1;
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}
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// adjust argv (remove mldr's argv[0])
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// NOTE: this code assumes that the current argv array points to contiguous strings.
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// this is not necessarily true, although AFAIK this is always true on Linux.
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// also note: we do it this way (moving the string contents in addition to the pointers)
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// so that Linux sees our modified argv array without having to use PR_SET_MM_ARG_START
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// and PR_SET_MM_ARG_END (since those require CAP_SYS_RESOURCE)
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// adjust argv (remove mldr's argv[0])
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--mldr_load_results.argc;
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orig_argv0_len = strlen(mldr_load_results.argv[0]) + 1;
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orig_argv1 = mldr_load_results.argv[1];
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for (size_t i = 0; i < mldr_load_results.argc; ++i) {
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mldr_load_results.argv[i] = mldr_load_results.argv[i + 1];
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mldr_load_results.argv[i] = mldr_load_results.argv[0] + arg_strings_total_size_after;
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arg_strings_total_size_after += strlen(mldr_load_results.argv[i + 1]) + 1;
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}
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mldr_load_results.argv[mldr_load_results.argc] = NULL;
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memmove(mldr_load_results.argv[0], orig_argv1, arg_strings_total_size_after);
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memset(mldr_load_results.argv[0] + arg_strings_total_size_after, 0, orig_argv0_len);
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if (p == NULL) {
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vchroot_unexpand_interpreter(&mldr_load_results);
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}
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// adjust envp (remove special mldr variables)
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// NOTE: same as for argv; here we assume the envp strings are contiguous
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for (size_t i = 0; i < mldr_load_results.envc; ++i) {
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if (!mldr_load_results.envp[i]) {
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mldr_load_results.envc = i;
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break;
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}
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size_t len = strlen(mldr_load_results.envp[i]) + 1;
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// Don't pass these special env vars down to userland
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#define SKIP_VAR(_name) \
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(len > sizeof(_name) - 1 && strncmp(mldr_load_results.envp[i], _name, sizeof(_name) - 1) == 0)
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if (
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SKIP_VAR("__mldr_bprefs=") ||
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SKIP_VAR("__mldr_sockpath=")
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) {
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size_t len_after = 0;
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const char* orig_envp_i_plus_one = mldr_load_results.envp[i + 1];
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--mldr_load_results.envc;
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for (size_t j = i; j < mldr_load_results.envc; ++j) {
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mldr_load_results.envp[j] = mldr_load_results.envp[i] + len_after;
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len_after += strlen(mldr_load_results.envp[j + 1]) + 1;
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}
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mldr_load_results.envp[mldr_load_results.envc] = NULL;
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memmove(mldr_load_results.envp[i], orig_envp_i_plus_one, len_after);
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memset(mldr_load_results.envp[i] + len_after, 0, len);
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// we have to check this index again because it now points to a different string
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--i;
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continue;
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}
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}
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if (mldr_load_results._32on64)
-53
src/startup/mldr/stack.c
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src/startup/mldr/stack.c
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#include "loader.h"
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#include <darling-config.h>
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#include "elfcalls/elfcalls.h"
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#include <sys/prctl.h>
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#if defined(GEN_64BIT)
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#define FUNCTION_NAME setup_stack64
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}
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// Fill in argv pointers
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// NOTE: the prctl code assumes that the current argv array points to contiguous strings.
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// this is not necessarily true, although AFAIK this is always true on Linux.
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// nonetheless, we should probably not assume this.
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argv = sp;
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uintptr_t arg_space_ptr = lr->argv[0];
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if (prctl(PR_SET_MM, PR_SET_MM_ARG_START, arg_space_ptr, 0, 0) < 0) {
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// maybe arg_end was behind arg_start; try moving it first
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if (prctl(PR_SET_MM, PR_SET_MM_ARG_END, arg_space_ptr, 0, 0) < 0) {
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fprintf(stderr, "Failed to set arg end\n");
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exit(1);
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}
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if (prctl(PR_SET_MM, PR_SET_MM_ARG_START, arg_space_ptr, 0, 0) < 0) {
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fprintf(stderr, "Failed to set arg start\n");
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exit(1);
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}
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}
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for (int i = 0; i < lr->argc; ++i)
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{
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if (!lr->argv[i]) {
···
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fprintf(stderr, "Failed to copy an argument pointer to stack\n");
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exit(1);
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}
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arg_space_ptr += strlen(lr->argv[i]) + 1;
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}
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if (__put_user((user_long_t) 0, argv++))
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{
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fprintf(stderr, "Failed to null-terminate the argument pointer array\n");
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exit(1);
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}
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if (prctl(PR_SET_MM, PR_SET_MM_ARG_END, arg_space_ptr, 0, 0) < 0) {
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fprintf(stderr, "Failed to set arg end\n");
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exit(1);
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}
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// Fill in envp pointers
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// NOTE: same as for argv; here we assume the envp strings are contiguous
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envp = argv;
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uintptr_t env_space_ptr = lr->envp[0];
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if (prctl(PR_SET_MM, PR_SET_MM_ENV_START, env_space_ptr, 0, 0) < 0) {
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// maybe env_end was behind env_start; try moving it first
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if (prctl(PR_SET_MM, PR_SET_MM_ENV_END, env_space_ptr, 0, 0) < 0) {
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fprintf(stderr, "Failed to set env end\n");
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exit(1);
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}
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if (prctl(PR_SET_MM, PR_SET_MM_ENV_START, env_space_ptr, 0, 0) < 0) {
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fprintf(stderr, "Failed to set env start\n");
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exit(1);
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}
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}
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for (int i = 0; i < lr->envc; ++i)
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{
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if (!lr->envp[i]) {
···
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break;
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}
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size_t len = strlen((void __user*) lr->envp[i]) + 1;
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// Don't pass these special env vars down to userland
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#define SKIP_VAR(_name) \
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if (len > sizeof(_name) - 1 && strncmp(lr->envp[i], _name, sizeof(_name) - 1) == 0) { \
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env_space_ptr += strlen(lr->envp[i]) + 1; \
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continue; \
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}
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SKIP_VAR("__mldr_bprefs=");
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SKIP_VAR("__mldr_sockpath=");
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if (__put_user((user_long_t) lr->envp[i], envp++))
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{
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fprintf(stderr, "Failed to copy an environment variable pointer to stack\n");
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exit(1);
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}
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env_space_ptr += strlen(lr->envp[i]) + 1;
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}
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if (__put_user((user_long_t) 0, envp++))
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{
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fprintf(stderr, "Failed to null-terminate the environment variable pointer array\n");
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exit(1);
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}
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// FIXME: this might include variables that we've skipped
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if (prctl(PR_SET_MM, PR_SET_MM_ENV_END, env_space_ptr, 0, 0) < 0) {
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fprintf(stderr, "Failed to set env end\n");
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exit(1);
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}
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