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dmeventd: Don't trust fifo with wrong attrs.

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If an existing fifo has the wrong attributes it cannot be trusted
so we must unlink it and recreate it correctly.
(Replaces 2c8d6f5c90: if the other end of
the fifo already got opened while its mode was insecure, delaying the
chmod isn't going to make any difference!)
This commit is contained in:
Alasdair G Kergon 2015-12-08 01:48:17 +00:00
parent 94dab390ef
commit dcd946e95a
1 changed files with 25 additions and 9 deletions
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34
daemons/dmeventd/dmeventd.c
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@ -408,7 +408,7 @@ static struct thread_status *_alloc_thread_status(const struct message_data *dat
if (!(thread->device.uuid = dm_strdup(data->device_uuid)))
goto_out;
/* Until real name resolved, use UUID */
/* Until real name resolved, use UUID */
if (!(thread->device.name = dm_strdup(data->device_uuid)))
goto_out;
@ -1359,6 +1359,26 @@ static int _open_fifo(const char *path)
{
struct stat st;
int fd = -1;
/*
* FIXME Explicitly verify the code's requirement that path is secure:
* - All parent directories owned by root without group/other write access unless sticky.
*/
/* If path exists, only use it if it is root-owned fifo mode 0600 */
if ((lstat(path, &st) < 0)) {
if (errno != ENOENT) {
log_sys_error("stat", path);
return -1;
}
} else if (!S_ISFIFO(st.st_mode) || st.st_uid ||
(st.st_mode & (S_IEXEC | S_IRWXG | S_IRWXO))) {
log_warn("WARNING: %s has wrong attributes: Replacing.", path);
if (unlink(path)) {
log_sys_error("unlink", path);
return -1;
}
}
/* Create fifo. */
(void) dm_prepare_selinux_context(path, S_IFIFO);
@ -1382,14 +1402,10 @@ static int _open_fifo(const char *path)
goto fail;
}
if ((st.st_mode & 0777) != 0600) {
log_warn("WARNING: Fixing wrong permissions on %s: %s.",
path, strerror(errno));
if (fchmod(fd, 0600)) {
log_sys_error("fchmod", path);
goto fail;
}
if (!S_ISFIFO(st.st_mode) || st.st_uid ||
(st.st_mode & (S_IEXEC | S_IRWXG | S_IRWXO))) {
log_error("%s: fifo has incorrect attributes", path);
goto fail;
}
if (fcntl(fd, F_SETFD, FD_CLOEXEC)) {