Created
August 18, 2024 05:16
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| #include <sys/cdefs.h> | |
| #include <sys/ioctl.h> | |
| #include <sys/param.h> | |
| #include <sys/conf.h> | |
| #include <fs/devfs/devfs.h> | |
| #include <fcntl.h> | |
| #include <errno.h> | |
| #include <err.h> | |
| #include <iostream> | |
| #include <exception> | |
| #include <vector> | |
| #include <string> | |
| static devfs_rsnum first_free_ruleset(int fd) { | |
| devfs_rsnum prev = 0; | |
| devfs_rsnum current = 0; | |
| while (current < (devfs_rsnum)-1) { | |
| prev = current; | |
| int rv = ioctl(fd, DEVFSIO_SGETNEXT, ¤t); | |
| if (rv == -1 && errno != ENOENT) { | |
| throw std::runtime_error("DEVFSIO_SGETNEXT"); | |
| } else if(current - prev > 1) { | |
| // There's a gap between the rulesets | |
| return prev + 1; | |
| } else if(rv == -1) { | |
| // current is the final ruleset | |
| return current + 1; | |
| } | |
| } | |
| throw std::runtime_error("no free rulesets"); | |
| } | |
| void real_main() { | |
| int fd = open("/dev/", O_RDONLY); | |
| if (fd < 0) throw std::runtime_error("could not open dev"); | |
| devfs_rsnum ruleset = first_free_ruleset(fd); | |
| std::cout << "next free ruleset: " << ruleset << std::endl; | |
| struct devfs_rule rule{}; | |
| rule.dr_magic = DEVFS_MAGIC; | |
| // rule id 0 means allocate new ID | |
| rule.dr_id = mkrid(ruleset, 0); | |
| rule.dr_iacts = DRA_BACTS; | |
| rule.dr_bacts = DRB_HIDE; | |
| if (ioctl(fd, DEVFSIO_RADD, &rule) == -1) throw std::runtime_error("DEVFSIO_RADD"); | |
| std::vector<std::string> unhide_names = { | |
| "null", | |
| "zero", | |
| "random", | |
| "urandom", | |
| "pts", | |
| "pts/*", | |
| "fd", | |
| "fd/*", | |
| "stdin", | |
| "stdout", | |
| "stderr" | |
| }; | |
| for(auto& name : unhide_names) { | |
| if(name.size() > DEVFS_MAXPTRNLEN) { | |
| throw std::runtime_error("pattern too long"); | |
| } | |
| struct devfs_rule rule{}; | |
| rule.dr_magic = DEVFS_MAGIC; | |
| rule.dr_id = mkrid(ruleset, 0); | |
| rule.dr_iacts = DRA_BACTS; | |
| rule.dr_bacts = DRB_UNHIDE; | |
| rule.dr_icond = DRC_PATHPTRN; | |
| strcpy(rule.dr_pathptrn, name.data()); | |
| if (ioctl(fd, DEVFSIO_RADD, &rule) == -1) throw std::runtime_error("DEVFSIO_RADD"); | |
| } | |
| } | |
| int main() { | |
| try { | |
| real_main(); | |
| } catch(const std::exception& ex) { | |
| std::cout << ex.what() << std::endl; | |
| } | |
| return 0; | |
| } |
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