util_run_program: restore signal mask before executing event RUN commands

External programs triggered by events (via RUN=) will inherit udev's
signal mask, which is set to block all but SIGALRM. For most utilities,
this is OK, but if we start daemons from RUN=, we run into trouble
(especially as SIGCHLD is blocked).

This change saves the original sigmask when udev starts, and restores it
just before we exec() the external command.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>

diff --git a/libudev/libudev-private.h b/libudev/libudev-private.h
index b735298c67a61bdfd151c1fd0f8a9a5c95d433c4..e90c79cb3edb77d446de328c75f0f7859de7bcf9 100644 (file)
--- a/libudev/libudev-private.h
+++ b/libudev/libudev-private.h
@@ -13,6 +13,7 @@
 #define _LIBUDEV_PRIVATE_H_
 
 #include <syslog.h>
+#include <signal.h>
 #include "libudev.h"
 
 #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
@@ -214,7 +215,8 @@ int util_unlink_secure(struct udev *udev, const char *filename);
 uid_t util_lookup_user(struct udev *udev, const char *user);
 gid_t util_lookup_group(struct udev *udev, const char *group);
 int util_run_program(struct udev *udev, const char *command, char **envp,
-                    char *result, size_t ressize, size_t *reslen);
+                    char *result, size_t ressize, size_t *reslen,
+                    const sigset_t *sigmask);
 int util_resolve_subsys_kernel(struct udev *udev, const char *string,
                                      char *result, size_t maxsize, int read_value);
 

diff --git a/libudev/libudev-util-private.c b/libudev/libudev-util-private.c
index fe8f29b3a89007e20b595a73693644e4b18484ca..dfde5a998d3413109239eb93cf77e0bf006eaed2 100644 (file)
--- a/libudev/libudev-util-private.c
+++ b/libudev/libudev-util-private.c
@@ -242,7 +242,8 @@ int util_resolve_subsys_kernel(struct udev *udev, const char *string,
 }
 
 int util_run_program(struct udev *udev, const char *command, char **envp,
-                    char *result, size_t ressize, size_t *reslen)
+                    char *result, size_t ressize, size_t *reslen,
+                    const sigset_t *sigmask)
 {
        int status;
        int outpipe[2] = {-1, -1};
@@ -330,6 +331,10 @@ int util_run_program(struct udev *udev, const char *command, char **envp,
                        dup2(errpipe[WRITE_END], STDERR_FILENO);
                        close(errpipe[WRITE_END]);
                }
+
+               if (sigmask)
+                       sigprocmask(SIG_BLOCK, sigmask, NULL);
+
                execve(argv[0], argv, envp);
                if (errno == ENOENT || errno == ENOTDIR) {
                        /* may be on a filesystem which is not mounted right now */

diff --git a/udev/test-udev.c b/udev/test-udev.c
index c6b8bf573ba774b7d7464906cff1a42f1935fca3..0806fbf9ce5fb04a8b480c104b928a285c00f86e 100644 (file)
--- a/udev/test-udev.c
+++ b/udev/test-udev.c
@@ -103,7 +103,7 @@ int main(int argc, char *argv[])
                alarm(udev_device_get_event_timeout(dev));
 
        if (err == 0 && !event->ignore_device && udev_get_run(udev))
-               udev_event_execute_run(event);
+               udev_event_execute_run(event, NULL);
 
        udev_event_unref(event);
        udev_device_unref(dev);

diff --git a/udev/udev-event.c b/udev/udev-event.c
index 8183793e5f4536824b3fd62fc0b0f207daf0a275..7b4e4ac5c3cf892224067e9e99c714534539634c 100644 (file)
--- a/udev/udev-event.c
+++ b/udev/udev-event.c
@@ -722,7 +722,7 @@ exit:
        return err;
 }
 
-int udev_event_execute_run(struct udev_event *event)
+int udev_event_execute_run(struct udev_event *event, const sigset_t *sigmask)
 {
        struct udev_list_entry *list_entry;
        int err = 0;
@@ -745,7 +745,7 @@ int udev_event_execute_run(struct udev_event *event)
 
                        udev_event_apply_format(event, cmd, program, sizeof(program));
                        envp = udev_device_get_properties_envp(event->dev);
-                       if (util_run_program(event->udev, program, envp, NULL, 0, NULL) != 0) {
+                       if (util_run_program(event->udev, program, envp, NULL, 0, NULL, sigmask) != 0) {
                                if (udev_list_entry_get_flag(list_entry))
                                        err = -1;
                        }

diff --git a/udev/udev-rules.c b/udev/udev-rules.c
index a92446403ff2604568814d455cd907ffd3c63895..20ec2706bdfa99cf24bdf8c1b391804713f7df75 100644 (file)
--- a/udev/udev-rules.c
+++ b/udev/udev-rules.c
@@ -749,7 +749,7 @@ static int import_program_into_properties(struct udev_device *dev, const char *p
        char *line;
 
        envp = udev_device_get_properties_envp(dev);
-       if (util_run_program(udev, program, envp, result, sizeof(result), &reslen) != 0)
+       if (util_run_program(udev, program, envp, result, sizeof(result), &reslen, NULL) != 0)
                return -1;
 
        line = result;
@@ -2206,7 +2206,7 @@ int udev_rules_apply_to_event(struct udev_rules *rules, struct udev_event *event
                                     program,
                                     &rules->buf[rule->rule.filename_off],
                                     rule->rule.filename_line);
-                               if (util_run_program(event->udev, program, envp, result, sizeof(result), NULL) != 0) {
+                               if (util_run_program(event->udev, program, envp, result, sizeof(result), NULL, NULL) != 0) {
                                        if (cur->key.op != OP_NOMATCH)
                                                goto nomatch;
                                } else {

diff --git a/udev/udev.h b/udev/udev.h
index 391276f6e42546ac0dd8ad6af508889ff47ddc6f..8f0a3014b647f8eb946073c7127d7bf72e279663 100644 (file)
--- a/udev/udev.h
+++ b/udev/udev.h
@@ -21,6 +21,7 @@
 
 #include <sys/types.h>
 #include <sys/param.h>
+#include <signal.h>
 
 #include "libudev.h"
 #include "libudev-private.h"
@@ -67,7 +68,7 @@ int udev_rules_apply_to_event(struct udev_rules *rules, struct udev_event *event
 struct udev_event *udev_event_new(struct udev_device *dev);
 void udev_event_unref(struct udev_event *event);
 int udev_event_execute_rules(struct udev_event *event, struct udev_rules *rules);
-int udev_event_execute_run(struct udev_event *event);
+int udev_event_execute_run(struct udev_event *event, const sigset_t *sigset);
 size_t udev_event_apply_format(struct udev_event *event, const char *src, char *dest, size_t size);
 int udev_event_apply_subsys_kernel(struct udev_event *event, const char *string,
                                   char *result, size_t maxsize, int read_value);

diff --git a/udev/udevd.c b/udev/udevd.c
index 54064cbfcf58de88aa7232805d3ef92aaf800e3f..2eb914a3f335f61952b355328ef9c8fae707b559 100644 (file)
--- a/udev/udevd.c
+++ b/udev/udevd.c
@@ -79,6 +79,7 @@ static bool stop_exec_queue;
 static bool reload_config;
 static int max_childs;
 static int childs;
+static sigset_t orig_sigmask;
 static struct udev_list_node event_list;
 static struct udev_list_node worker_list;
 static bool udev_exit;
@@ -292,7 +293,8 @@ static void worker_new(struct event *event)
 
                        /* execute RUN= */
                        if (err == 0 && !udev_event->ignore_device && udev_get_run(udev_event->udev))
-                               failed = udev_event_execute_run(udev_event);
+                               failed = udev_event_execute_run(udev_event,
+                                                               &orig_sigmask);
 
                        /* reset alarm */
                        alarm(0);
@@ -926,7 +928,7 @@ int main(int argc, char *argv[])
 
        /* block and listen to all signals on signalfd */
        sigfillset(&mask);
-       sigprocmask(SIG_SETMASK, &mask, NULL);
+       sigprocmask(SIG_SETMASK, &mask, &orig_sigmask);
        pfd[FD_SIGNAL].fd = signalfd(-1, &mask, 0);
        if (pfd[FD_SIGNAL].fd < 0) {
                fprintf(stderr, "error getting signalfd\n");