[Libguestfs] [PATCH] lib: Limit space and time used by 'qemu-img info' subprocess.
Richard W.M. Jones
rjones at redhat.com
Tue May 26 12:34:29 UTC 2015
After fuzzing 'qemu-img info' I found that certain files can cause the
command to use lots of memory and time. Modify the command
mini-library to allow us to place resource limits on subprocesses, and
use these to limit the amount of space and time used by 'qemu-img info'.
---
configure.ac | 3 +++
src/command.c | 53 ++++++++++++++++++++++++++++++++++++++++++++++++++
src/guestfs-internal.h | 1 +
src/info.c | 22 ++++++++++++++++++++-
4 files changed, 78 insertions(+), 1 deletion(-)
diff --git a/configure.ac b/configure.ac
index acd807b..6fea1e4 100644
--- a/configure.ac
+++ b/configure.ac
@@ -305,8 +305,10 @@ AC_CHECK_HEADERS([\
linux/raid/md_u.h \
printf.h \
sys/inotify.h \
+ sys/resource.h \
sys/socket.h \
sys/statvfs.h \
+ sys/time.h \
sys/types.h \
sys/un.h \
sys/wait.h \
@@ -335,6 +337,7 @@ AC_CHECK_FUNCS([\
posix_fadvise \
removexattr \
setitimer \
+ setrlimit \
setxattr \
sigaction \
statvfs \
diff --git a/src/command.c b/src/command.c
index 45ae5d6..993198a 100644
--- a/src/command.c
+++ b/src/command.c
@@ -77,6 +77,13 @@
#include <sys/wait.h>
#include <sys/select.h>
+#ifdef HAVE_SYS_TIME_H
+#include <sys/time.h>
+#endif
+#ifdef HAVE_SYS_RESOURCE_H
+#include <sys/resource.h>
+#endif
+
#include "guestfs.h"
#include "guestfs-internal.h"
@@ -101,6 +108,12 @@ struct buffering {
void (*close_data) (struct command *cmd);
};
+struct child_rlimits {
+ struct child_rlimits *next;
+ int resource;
+ long limit;
+};
+
struct command
{
guestfs_h *g;
@@ -139,6 +152,9 @@ struct command
cmd_child_callback child_callback;
void *child_callback_data;
+ /* Optional child limits. */
+ struct child_rlimits *child_rlimits;
+
/* Optional stdin forwarding to the child. */
int infd;
};
@@ -329,6 +345,22 @@ guestfs_int_cmd_set_child_callback (struct command *cmd,
cmd->child_callback_data = data;
}
+/* Set up child rlimits, in case the process we are running could
+ * consume lots of space or time.
+ */
+void
+guestfs_int_cmd_set_child_rlimit (struct command *cmd, int resource, long limit)
+{
+ struct child_rlimits *p;
+
+ p = safe_malloc (cmd->g, sizeof *p);
+ p->resource = resource;
+ p->limit = limit;
+ p->next = cmd->child_rlimits;
+ cmd->child_rlimits = p;
+}
+
+
/* Finish off the command by either NULL-terminating the argv array or
* adding a terminating \0 to the string, or die with an internal
* error if no command has been added.
@@ -390,6 +422,10 @@ run_command (struct command *cmd, bool get_stdin_fd, bool get_stdout_fd,
int outfd[2] = { -1, -1 };
int infd[2] = { -1, -1 };
char status_string[80];
+#ifdef HAVE_SETRLIMIT
+ struct child_rlimits *child_rlimit;
+ struct rlimit rlimit;
+#endif
get_stdout_fd = get_stdout_fd || cmd->stdout_callback != NULL;
get_stderr_fd = get_stderr_fd || cmd->capture_errors;
@@ -510,6 +546,23 @@ run_command (struct command *cmd, bool get_stdin_fd, bool get_stdout_fd,
_exit (EXIT_FAILURE);
}
+#ifdef HAVE_SETRLIMIT
+ for (child_rlimit = cmd->child_rlimits;
+ child_rlimit != NULL;
+ child_rlimit = child_rlimit->next) {
+ rlimit.rlim_cur = rlimit.rlim_max = child_rlimit->limit;
+ if (setrlimit (child_rlimit->resource, &rlimit) == -1) {
+ /* EPERM means we're trying to raise the limit (ie. the limit is
+ * already more restrictive than what we want), so ignore it.
+ */
+ if (errno != EPERM) {
+ perror ("setrlimit");
+ _exit (EXIT_FAILURE);
+ }
+ }
+ }
+#endif /* HAVE_SETRLIMIT */
+
/* Run the command. */
switch (cmd->style) {
case COMMAND_STYLE_EXECV:
diff --git a/src/guestfs-internal.h b/src/guestfs-internal.h
index 414a634..4f06c37 100644
--- a/src/guestfs-internal.h
+++ b/src/guestfs-internal.h
@@ -864,6 +864,7 @@ extern void guestfs_int_cmd_set_stdout_callback (struct command *, cmd_stdout_ca
#define CMD_STDOUT_FLAG_UNBUFFERED 1
#define CMD_STDOUT_FLAG_WHOLE_BUFFER 2
extern void guestfs_int_cmd_set_stderr_to_stdout (struct command *);
+extern void guestfs_int_cmd_set_child_rlimit (struct command *, int resource, long limit);
extern void guestfs_int_cmd_clear_capture_errors (struct command *);
extern void guestfs_int_cmd_clear_close_files (struct command *);
extern void guestfs_int_cmd_set_child_callback (struct command *, cmd_child_callback child_callback, void *data);
diff --git a/src/info.c b/src/info.c
index bd4221c..bfd7860 100644
--- a/src/info.c
+++ b/src/info.c
@@ -31,6 +31,14 @@
#include <assert.h>
#include <string.h>
+#ifdef HAVE_SYS_TIME_H
+#include <sys/time.h>
+#endif
+
+#ifdef HAVE_SYS_RESOURCE_H
+#include <sys/resource.h>
+#endif
+
#if HAVE_YAJL
#include <yajl/yajl_tree.h>
#endif
@@ -269,7 +277,13 @@ get_json_output (guestfs_h *g, const char *filename)
guestfs_int_cmd_add_arg (cmd, "json");
guestfs_int_cmd_add_arg (cmd, fdpath);
guestfs_int_cmd_set_stdout_callback (cmd, parse_json, &tree,
- CMD_STDOUT_FLAG_WHOLE_BUFFER);
+ CMD_STDOUT_FLAG_WHOLE_BUFFER);
+#ifdef RLIMIT_AS
+ guestfs_int_cmd_set_child_rlimit (cmd, RLIMIT_AS, 1000000000 /* 1GB */);
+#endif
+#ifdef RLIMIT_CPU
+ guestfs_int_cmd_set_child_rlimit (cmd, RLIMIT_CPU, 10 /* seconds */);
+#endif
r = guestfs_int_cmd_run (cmd);
close (fd);
if (r == -1)
@@ -548,6 +562,12 @@ old_parser_run_qemu_img_info (guestfs_h *g, const char *filename,
guestfs_int_cmd_add_arg (cmd, "info");
guestfs_int_cmd_add_arg (cmd, safe_filename);
guestfs_int_cmd_set_stdout_callback (cmd, fn, data, 0);
+#ifdef RLIMIT_AS
+ guestfs_int_cmd_set_child_rlimit (cmd, RLIMIT_AS, 1000000000 /* 1GB */);
+#endif
+#ifdef RLIMIT_CPU
+ guestfs_int_cmd_set_child_rlimit (cmd, RLIMIT_CPU, 10 /* seconds */);
+#endif
r = guestfs_int_cmd_run (cmd);
if (r == -1)
return -1;
--
2.3.1
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