parse: rework config parsing routine

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

diff --git a/src/lxc/file_utils.c b/src/lxc/file_utils.c
index fafaba354c176dddbe43a2f60ad5d9d258eb7289..3b4bffb3990a4c227a9727dfc1fd555068060446 100644 (file)
--- a/src/lxc/file_utils.c
+++ b/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 a/src/lxc/file_utils.h b/src/lxc/file_utils.h
index ea9570dd18b78f7498a36dce652c51b06d2c6abe..11acdb3a7b027b75fb5a89b72fec49bdcbdd2722 100644 (file)
--- a/src/lxc/file_utils.h
+++ b/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 a/src/lxc/parse.c b/src/lxc/parse.c
index 291bf3efc146ffcc240836a4712cc3fc96f58ad2..5a5b8534587338bdaeeb2b373cbb188653a489b8 100644 (file)
--- a/src/lxc/parse.c
+++ b/src/lxc/parse.c
@@ -5,6 +5,7 @@
 #endif
 #include <dirent.h>
 #include <errno.h>
+#include <limits.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -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;
 }