mirror of
https://github.com/topjohnwu/Magisk.git
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528601d25a
- Use ftruncate64 instead of ftruncate to workaround seccomp - Cast uint32_t to off64_t before making it negative Note: Using ftruncate with a modern NDK libc should actually be fine as the syscall wrapper in bionic will use ftruncate64 internally. However, since we are using the libc.a from r10e built for Gingerbread, seccomp wasn't a thing back then, and also the ftruncate64 symbol is missing; we have to create our own wrapper and call it instead on 32-bit ABIs. Props to @jnotuo for discovering the overflow bug and seccomp issue Fix #3703, close #4915
150 lines
4.3 KiB
C++
150 lines
4.3 KiB
C++
// This file implements all missing symbols that should exist in normal API 21
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// libc.a but missing in our extremely lean libc.a replacements.
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#include <cstdlib>
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#include <cstring>
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#include <cerrno>
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#include <mntent.h>
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#include <unistd.h>
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#include <sys/syscall.h>
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extern "C" {
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/* Original source: https://github.com/freebsd/freebsd/blob/master/contrib/file/src/getline.c
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* License: BSD, full copyright notice please check original source */
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ssize_t getdelim(char **buf, size_t *bufsiz, int delimiter, FILE *fp) {
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char *ptr, *eptr;
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if (*buf == nullptr || *bufsiz == 0) {
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*bufsiz = BUFSIZ;
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if ((*buf = (char *) malloc(*bufsiz)) == nullptr)
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return -1;
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}
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for (ptr = *buf, eptr = *buf + *bufsiz;;) {
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int c = fgetc(fp);
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if (c == -1) {
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if (feof(fp))
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return ptr == *buf ? -1 : ptr - *buf;
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else
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return -1;
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}
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*ptr++ = c;
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if (c == delimiter) {
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*ptr = '\0';
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return ptr - *buf;
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}
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if (ptr + 2 >= eptr) {
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char *nbuf;
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size_t nbufsiz = *bufsiz * 2;
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ssize_t d = ptr - *buf;
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if ((nbuf = (char *) realloc(*buf, nbufsiz)) == nullptr)
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return -1;
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*buf = nbuf;
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*bufsiz = nbufsiz;
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eptr = nbuf + nbufsiz;
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ptr = nbuf + d;
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}
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}
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}
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ssize_t getline(char **buf, size_t *bufsiz, FILE *fp) {
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return getdelim(buf, bufsiz, '\n', fp);
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}
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/* Original source: https://android.googlesource.com/platform/bionic/+/master/libc/bionic/mntent.cpp
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* License: AOSP, full copyright notice please check original source */
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struct mntent *getmntent_r(FILE *fp, struct mntent *e, char *buf, int buf_len) {
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memset(e, 0, sizeof(*e));
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while (fgets(buf, buf_len, fp) != nullptr) {
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// Entries look like "proc /proc proc rw,nosuid,nodev,noexec,relatime 0 0".
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// That is: mnt_fsname mnt_dir mnt_type mnt_opts 0 0.
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int fsname0, fsname1, dir0, dir1, type0, type1, opts0, opts1;
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if (sscanf(buf, " %n%*s%n %n%*s%n %n%*s%n %n%*s%n %d %d",
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&fsname0, &fsname1, &dir0, &dir1, &type0, &type1, &opts0, &opts1,
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&e->mnt_freq, &e->mnt_passno) == 2) {
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e->mnt_fsname = &buf[fsname0];
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buf[fsname1] = '\0';
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e->mnt_dir = &buf[dir0];
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buf[dir1] = '\0';
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e->mnt_type = &buf[type0];
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buf[type1] = '\0';
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e->mnt_opts = &buf[opts0];
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buf[opts1] = '\0';
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return e;
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}
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}
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return nullptr;
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}
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FILE *setmntent(const char *path, const char *mode) {
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return fopen(path, mode);
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}
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int endmntent(FILE *fp) {
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if (fp != nullptr) {
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fclose(fp);
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}
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return 1;
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}
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// Missing system call wrappers
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int setns(int fd, int nstype) {
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return syscall(__NR_setns, fd, nstype);
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}
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int unshare(int flags) {
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return syscall(__NR_unshare, flags);
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}
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int accept4(int sockfd, struct sockaddr *addr, socklen_t *addrlen, int flags) {
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return syscall(__NR_accept4, sockfd, addr, addrlen, flags);
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}
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int dup3(int oldfd, int newfd, int flags) {
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return syscall(__NR_dup3, oldfd, newfd, flags);
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}
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ssize_t readlinkat(int dirfd, const char *pathname, char *buf, size_t bufsiz) {
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return syscall(__NR_readlinkat, dirfd, pathname, buf, bufsiz);
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}
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int symlinkat(const char *target, int newdirfd, const char *linkpath) {
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return syscall(__NR_symlinkat, target, newdirfd, linkpath);
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}
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int linkat(int olddirfd, const char *oldpath,
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int newdirfd, const char *newpath, int flags) {
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return syscall(__NR_linkat, olddirfd, oldpath, newdirfd, newpath, flags);
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}
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int inotify_init1(int flags) {
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return syscall(__NR_inotify_init1, flags);
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}
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int faccessat(int dirfd, const char *pathname, int mode, int flags) {
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return syscall(__NR_faccessat, dirfd, pathname, mode, flags);
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}
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#define SPLIT_64(v) (unsigned)((v) & 0xFFFFFFFF), (unsigned)((v) >> 32)
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#if defined(__arm__)
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// Why the additional 0 is required: https://man7.org/linux/man-pages/man2/syscall.2.html
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int ftruncate64(int fd, off64_t length) {
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return syscall(__NR_ftruncate64, fd, 0, SPLIT_64(length));
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}
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#elif defined(__i386__)
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int ftruncate64(int fd, off64_t length) {
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return syscall(__NR_ftruncate64, fd, SPLIT_64(length));
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}
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#endif
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#if !defined(__LP64__)
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void android_set_abort_message(const char *msg) {}
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#endif
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} // extern "C"
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