mirror of
https://github.com/topjohnwu/Magisk.git
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49f259065d
In the current implementation, Magisk will either have to recreate all early mount implementation (for legacy SAR and rootfs devices) or delegate early mount to first stage init (for 2SI devices) to access required partitions for loading sepolicy. It then has to recreate the split sepolicy loading implementation in-house, apply patches, then dump the compiled + patched policies into monolithic format somewhere. Finally, it patches the original init to force it to load the sepolicy file we just created. With the increasing complexity involved in early mount and split sepolicy (there is even APEX module involved in the future!), it is about time to rethink Magisk's sepolicy strategy as rebuilding init's functionality is not scalable and easy to maintain. In this commit, instead of building sepolicy ourselves, we mock selinuxfs with FIFO files connected to a pre-init daemon, waiting for the actual init process to directly write the sepolicy file into MagiskInit. We then patch the file and load it into the kernel. Some FIFO tricks has to be used to hijack the original init process's control flow and prevent race conditions, details are directly in the comments in code. At the moment, only system-as-root (read-only root) support is added. Support for legacy rootfs devices will come with a follow up commit.
145 lines
4.4 KiB
C++
145 lines
4.4 KiB
C++
#pragma once
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#include <sys/mman.h>
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#include <sys/stat.h>
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#include <mntent.h>
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#include <functional>
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#include <string_view>
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#include <string>
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#include <vector>
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#include "xwrap.hpp"
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template <typename T>
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static inline T align_to(T v, int a) {
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static_assert(std::is_integral<T>::value);
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return (v + a - 1) / a * a;
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}
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template <typename T>
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static inline T align_padding(T v, int a) {
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return align_to(v, a) - v;
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}
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struct file_attr {
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struct stat st;
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char con[128];
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};
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struct byte_data {
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using str_pairs = std::initializer_list<std::pair<std::string_view, std::string_view>>;
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uint8_t *buf = nullptr;
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size_t sz = 0;
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int patch(str_pairs list) { return patch(true, list); }
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int patch(bool log, str_pairs list);
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bool contains(std::string_view pattern, bool log = true) const;
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protected:
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void swap(byte_data &o);
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};
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struct raw_file : public byte_data {
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std::string path;
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file_attr attr;
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raw_file() : attr{} {}
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raw_file(const raw_file&) = delete;
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raw_file(raw_file &&o) : path(std::move(o.path)), attr(o.attr) { swap(o); }
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~raw_file() { free(buf); }
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};
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struct mmap_data : public byte_data {
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mmap_data() = default;
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mmap_data(const mmap_data&) = delete;
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mmap_data(mmap_data &&o) { swap(o); }
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mmap_data(const char *name, bool rw = false);
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~mmap_data() { if (buf) munmap(buf, sz); }
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mmap_data& operator=(mmap_data &&other) { swap(other); return *this; }
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};
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ssize_t fd_path(int fd, char *path, size_t size);
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int fd_pathat(int dirfd, const char *name, char *path, size_t size);
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int mkdirs(std::string path, mode_t mode);
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void rm_rf(const char *path);
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void mv_path(const char *src, const char *dest);
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void mv_dir(int src, int dest);
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void cp_afc(const char *src, const char *dest);
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void link_path(const char *src, const char *dest);
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void link_dir(int src, int dest);
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int getattr(const char *path, file_attr *a);
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int getattrat(int dirfd, const char *name, file_attr *a);
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int fgetattr(int fd, file_attr *a);
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int setattr(const char *path, file_attr *a);
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int setattrat(int dirfd, const char *name, file_attr *a);
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int fsetattr(int fd, file_attr *a);
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void fclone_attr(int src, int dest);
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void clone_attr(const char *src, const char *dest);
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void fd_full_read(int fd, void **buf, size_t *size);
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void full_read(const char *filename, void **buf, size_t *size);
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void fd_full_read(int fd, std::string &str);
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void full_read(const char *filename, std::string &str);
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std::string fd_full_read(int fd);
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std::string full_read(const char *filename);
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void write_zero(int fd, size_t size);
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void file_readline(bool trim, FILE *fp, const std::function<bool(std::string_view)> &fn);
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static inline void file_readline(
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bool trim, const char *file, const std::function<bool(std::string_view)> &fn) {
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FILE *fp = xfopen(file, "re");
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if (fp == nullptr)
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return;
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file_readline(trim, fp, fn);
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}
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static inline void file_readline(const char *file,
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const std::function<bool(std::string_view)> &fn) {
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file_readline(false, file, fn);
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}
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void parse_prop_file(const char *file,
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const std::function<bool(std::string_view, std::string_view)> &fn);
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void frm_rf(int dirfd);
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void clone_dir(int src, int dest);
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void parse_mnt(const char *file, const std::function<bool(mntent*)> &fn);
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void backup_folder(const char *dir, std::vector<raw_file> &files);
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void restore_folder(const char *dir, std::vector<raw_file> &files);
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template <typename T>
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void full_read(const char *filename, T &buf, size_t &size) {
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static_assert(std::is_pointer<T>::value);
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full_read(filename, reinterpret_cast<void**>(&buf), &size);
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}
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template <typename T>
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void fd_full_read(int fd, T &buf, size_t &size) {
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static_assert(std::is_pointer<T>::value);
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fd_full_read(fd, reinterpret_cast<void**>(&buf), &size);
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}
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using sFILE = std::unique_ptr<FILE, decltype(&fclose)>;
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using sDIR = std::unique_ptr<DIR, decltype(&closedir)>;
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sDIR make_dir(DIR *dp);
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sFILE make_file(FILE *fp);
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static inline sDIR open_dir(const char *path) {
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return make_dir(opendir(path));
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}
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static inline sDIR xopen_dir(const char *path) {
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return make_dir(xopendir(path));
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}
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static inline sDIR xopen_dir(int dirfd) {
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return make_dir(xfdopendir(dirfd));
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}
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static inline sFILE open_file(const char *path, const char *mode) {
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return make_file(fopen(path, mode));
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}
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static inline sFILE xopen_file(const char *path, const char *mode) {
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return make_file(xfopen(path, mode));
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}
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static inline sFILE xopen_file(int fd, const char *mode) {
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return make_file(xfdopen(fd, mode));
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}
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