From 26dffd825842edf019bc17da24a6809ed51c048c Mon Sep 17 00:00:00 2001 From: Christian Brauner Date: Mon, 16 Nov 2020 12:18:14 +0100 Subject: [PATCH] parse: rework config parsing routine Signed-off-by: Christian Brauner --- src/lxc/file_utils.c | 7 +++++-- src/lxc/file_utils.h | 6 +++++- src/lxc/parse.c | 49 ++++++++++++++++++++++++-------------------- 3 files changed, 37 insertions(+), 25 deletions(-) diff --git src/lxc/file_utils.c src/lxc/file_utils.c index fafaba354c..3b4bffb399 100644 --- src/lxc/file_utils.c +++ src/lxc/file_utils.c @@ -382,8 +382,10 @@ ssize_t lxc_sendfile_nointr(int out_fd, int in_fd, off_t *offset, size_t count) return ret; } -int fd_to_fd(int from, int to) +ssize_t __fd_to_fd(int from, int to) { + ssize_t total_bytes = 0; + for (;;) { uint8_t buf[PATH_MAX]; uint8_t *p = buf; @@ -407,9 +409,10 @@ int fd_to_fd(int from, int to) bytes_to_write -= bytes_written; p += bytes_written; } while (bytes_to_write > 0); + total_bytes += bytes_to_write; } - return 0; + return total_bytes; } int fd_to_buf(int fd, char **buf, size_t *length) diff --git src/lxc/file_utils.h src/lxc/file_utils.h index ea9570dd18..11acdb3a7b 100644 --- src/lxc/file_utils.h +++ src/lxc/file_utils.h @@ -68,7 +68,11 @@ __hidden extern FILE *fopen_cloexec(const char *path, const char *mode); __hidden extern ssize_t lxc_sendfile_nointr(int out_fd, int in_fd, off_t *offset, size_t count); __hidden extern char *file_to_buf(const char *path, size_t *length); __hidden extern int fd_to_buf(int fd, char **buf, size_t *length); -__hidden extern int fd_to_fd(int from, int to); +__hidden extern ssize_t __fd_to_fd(int from, int to); +static inline int fd_to_fd(int from, int to) +{ + return __fd_to_fd(from, to) >= 0; +} __hidden extern int lxc_open_dirfd(const char *dir); __hidden extern FILE *fdopen_cached(int fd, const char *mode, void **caller_freed_buffer); __hidden extern FILE *fopen_cached(const char *path, const char *mode, void **caller_freed_buffer); diff --git src/lxc/parse.c src/lxc/parse.c index 291bf3efc1..5a5b853458 100644 --- src/lxc/parse.c +++ src/lxc/parse.c @@ -5,6 +5,7 @@ #endif #include #include +#include #include #include #include @@ -50,11 +51,12 @@ int lxc_strmunmap(void *addr, size_t length) int lxc_file_for_each_line_mmap(const char *file, lxc_file_cb callback, void *data) { - int saved_errno; - ssize_t ret = -1, bytes_sent; - char *line; - int fd = -1, memfd = -1; + __do_close int fd = -EBADF, memfd = -EBADF; + ssize_t ret = -1; char *buf = NULL; + struct stat st = {}; + ssize_t bytes; + char *line; memfd = memfd_create(".lxc_config_file", MFD_CLOEXEC); if (memfd < 0) { @@ -65,8 +67,7 @@ int lxc_file_for_each_line_mmap(const char *file, lxc_file_cb callback, void *da goto on_error; } - TRACE("Failed to create in-memory file. Falling back to " - "temporary file"); + TRACE("Failed to create in-memory file. Falling back to temporary file"); memfd = lxc_make_tmpfile(template, true); if (memfd < 0) { SYSERROR("Failed to create temporary file \"%s\"", template); @@ -80,10 +81,21 @@ int lxc_file_for_each_line_mmap(const char *file, lxc_file_cb callback, void *da goto on_error; } - /* sendfile() handles up to 2GB. No config file should be that big. */ - bytes_sent = lxc_sendfile_nointr(memfd, fd, NULL, LXC_SENDFILE_MAX); - if (bytes_sent < 0) { - SYSERROR("Failed to sendfile \"%s\"", file); + ret = fstat(fd, &st); + if (ret) { + SYSERROR("Failed to stat file \"%s\"", file); + goto on_error; + } + + if (st.st_size > INT_MAX) { + SYSERROR("Excessively large config file \"%s\"", file); + goto on_error; + } + + + bytes = __fd_to_fd(fd, memfd); + if (bytes < 0) { + SYSERROR("Failed to copy config file \"%s\"", file); goto on_error; } @@ -92,7 +104,7 @@ int lxc_file_for_each_line_mmap(const char *file, lxc_file_cb callback, void *da SYSERROR("Failed to append zero byte"); goto on_error; } - bytes_sent++; + bytes++; ret = lseek(memfd, 0, SEEK_SET); if (ret < 0) { @@ -101,8 +113,7 @@ int lxc_file_for_each_line_mmap(const char *file, lxc_file_cb callback, void *da } ret = -1; - buf = mmap(NULL, bytes_sent, PROT_READ | PROT_WRITE, - MAP_SHARED | MAP_POPULATE, memfd, 0); + buf = mmap(NULL, bytes, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_POPULATE, memfd, 0); if (buf == MAP_FAILED) { buf = NULL; SYSERROR("Failed to mmap"); @@ -117,24 +128,18 @@ int lxc_file_for_each_line_mmap(const char *file, lxc_file_cb callback, void *da * error. */ if (ret < 0) - ERROR("Failed to parse config file \"%s\" at " - "line \"%s\"", file, line); + ERROR("Failed to parse config file \"%s\" at line \"%s\"", + file, line); break; } } on_error: - saved_errno = errno; - if (fd >= 0) - close(fd); - if (memfd >= 0) - close(memfd); - if (buf && munmap(buf, bytes_sent)) { + if (buf && munmap(buf, bytes)) { SYSERROR("Failed to unmap"); if (ret == 0) ret = -1; } - errno = saved_errno; return ret; }