diff options
| -rw-r--r-- | nix/libstore/build.cc | 16 | ||||
| -rw-r--r-- | nix/libutil/util.cc | 112 | ||||
| -rw-r--r-- | nix/libutil/util.hh | 6 |
3 files changed, 129 insertions, 5 deletions
diff --git a/nix/libstore/build.cc b/nix/libstore/build.cc index 461fcbc584..e2adee118b 100644 --- a/nix/libstore/build.cc +++ b/nix/libstore/build.cc @@ -1382,6 +1382,22 @@ void DerivationGoal::buildDone() % drvPath % statusToString(status)); } + if (fixedOutput) { + /* Replace the output, if it exists, by a fresh copy of itself to + make sure that there's no stale file descriptor pointing to it + (CVE-2024-27297). */ + foreach (DerivationOutputs::iterator, i, drv.outputs) { + if (pathExists(i->second.path)) { + Path pivot = i->second.path + ".tmp"; + copyFileRecursively(i->second.path, pivot, true); + int err = rename(pivot.c_str(), i->second.path.c_str()); + if (err != 0) + throw SysError(format("renaming `%1%' to `%2%'") + % pivot % i->second.path); + } + } + } + /* Compute the FS closure of the outputs and register them as being valid. */ registerOutputs(); diff --git a/nix/libutil/util.cc b/nix/libutil/util.cc index 82eac72120..493f06f357 100644 --- a/nix/libutil/util.cc +++ b/nix/libutil/util.cc @@ -215,14 +215,11 @@ bool isLink(const Path & path) } -DirEntries readDirectory(const Path & path) +static DirEntries readDirectory(DIR *dir) { DirEntries entries; entries.reserve(64); - AutoCloseDir dir = opendir(path.c_str()); - if (!dir) throw SysError(format("opening directory `%1%'") % path); - struct dirent * dirent; while (errno = 0, dirent = readdir(dir)) { /* sic */ checkInterrupt(); @@ -230,11 +227,29 @@ DirEntries readDirectory(const Path & path) if (name == "." || name == "..") continue; entries.emplace_back(name, dirent->d_ino, dirent->d_type); } - if (errno) throw SysError(format("reading directory `%1%'") % path); + if (errno) throw SysError(format("reading directory")); return entries; } +DirEntries readDirectory(const Path & path) +{ + AutoCloseDir dir = opendir(path.c_str()); + if (!dir) throw SysError(format("opening directory `%1%'") % path); + return readDirectory(dir); +} + +static DirEntries readDirectory(int fd) +{ + /* Since 'closedir' closes the underlying file descriptor, duplicate FD + beforehand. */ + int fdcopy = dup(fd); + if (fdcopy < 0) throw SysError("dup"); + + AutoCloseDir dir = fdopendir(fdcopy); + if (!dir) throw SysError(format("opening directory from file descriptor `%1%'") % fd); + return readDirectory(dir); +} unsigned char getFileType(const Path & path) { @@ -364,6 +379,93 @@ void deletePath(const Path & path, unsigned long long & bytesFreed, size_t linkT _deletePath(path, bytesFreed, linkThreshold); } +static void copyFile(int sourceFd, int destinationFd) +{ + struct stat st; + if (fstat(sourceFd, &st) == -1) throw SysError("statting file"); + + ssize_t result = copy_file_range(sourceFd, NULL, destinationFd, NULL, st.st_size, 0); + if (result < 0 && errno == ENOSYS) { + for (size_t remaining = st.st_size; remaining > 0; ) { + unsigned char buf[8192]; + size_t count = std::min(remaining, sizeof buf); + + readFull(sourceFd, buf, count); + writeFull(destinationFd, buf, count); + remaining -= count; + } + } else { + if (result < 0) + throw SysError(format("copy_file_range `%1%' to `%2%'") % sourceFd % destinationFd); + if (result < st.st_size) + throw SysError(format("short write in copy_file_range `%1%' to `%2%'") + % sourceFd % destinationFd); + } +} + +static void copyFileRecursively(int sourceroot, const Path &source, + int destinationroot, const Path &destination, + bool deleteSource) +{ + struct stat st; + if (fstatat(sourceroot, source.c_str(), &st, AT_SYMLINK_NOFOLLOW) == -1) + throw SysError(format("statting file `%1%'") % source); + + if (S_ISREG(st.st_mode)) { + AutoCloseFD sourceFd = openat(sourceroot, source.c_str(), + O_CLOEXEC | O_NOFOLLOW | O_RDONLY); + if (sourceFd == -1) throw SysError(format("opening `%1%'") % source); + + AutoCloseFD destinationFd = openat(destinationroot, destination.c_str(), + O_CLOEXEC | O_CREAT | O_WRONLY | O_TRUNC, + st.st_mode); + if (destinationFd == -1) throw SysError(format("opening `%1%'") % source); + + copyFile(sourceFd, destinationFd); + } else if (S_ISLNK(st.st_mode)) { + char target[st.st_size + 1]; + ssize_t result = readlinkat(sourceroot, source.c_str(), target, st.st_size); + if (result != st.st_size) throw SysError("reading symlink target"); + target[st.st_size] = '\0'; + int err = symlinkat(target, destinationroot, destination.c_str()); + if (err != 0) + throw SysError(format("creating symlink `%1%'") % destination); + } else if (S_ISDIR(st.st_mode)) { + int err = mkdirat(destinationroot, destination.c_str(), 0755); + if (err != 0) + throw SysError(format("creating directory `%1%'") % destination); + + AutoCloseFD destinationFd = openat(destinationroot, destination.c_str(), + O_CLOEXEC | O_RDONLY | O_DIRECTORY); + if (err != 0) + throw SysError(format("opening directory `%1%'") % destination); + + AutoCloseFD sourceFd = openat(sourceroot, source.c_str(), + O_CLOEXEC | O_NOFOLLOW | O_RDONLY); + if (sourceFd == -1) + throw SysError(format("opening `%1%'") % source); + + if (deleteSource && !(st.st_mode & S_IWUSR)) { + /* Ensure the directory writable so files within it can be + deleted. */ + if (fchmod(sourceFd, st.st_mode | S_IWUSR) == -1) + throw SysError(format("making `%1%' directory writable") % source); + } + + for (auto & i : readDirectory(sourceFd)) + copyFileRecursively((int)sourceFd, i.name, (int)destinationFd, i.name, + deleteSource); + } else throw Error(format("refusing to copy irregular file `%1%'") % source); + + if (deleteSource) + unlinkat(sourceroot, source.c_str(), + S_ISDIR(st.st_mode) ? AT_REMOVEDIR : 0); +} + +void copyFileRecursively(const Path &source, const Path &destination, bool deleteSource) +{ + copyFileRecursively(AT_FDCWD, source, AT_FDCWD, destination, deleteSource); +} static Path tempName(Path tmpRoot, const Path & prefix, bool includePid, int & counter) diff --git a/nix/libutil/util.hh b/nix/libutil/util.hh index 880b0e93b2..058f5f8446 100644 --- a/nix/libutil/util.hh +++ b/nix/libutil/util.hh @@ -102,6 +102,12 @@ void deletePath(const Path & path); void deletePath(const Path & path, unsigned long long & bytesFreed, size_t linkThreshold = 1); +/* Copy SOURCE to DESTINATION, recursively. Throw if SOURCE contains a file + that is not a regular file, symlink, or directory. When DELETESOURCE is + true, delete source files once they have been copied. */ +void copyFileRecursively(const Path &source, const Path &destination, + bool deleteSource = false); + /* Create a temporary directory. */ Path createTempDir(const Path & tmpRoot = "", const Path & prefix = "nix", bool includePid = true, bool useGlobalCounter = true, mode_t mode = 0755); |