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e70d976)
Observed issue
==============
When starting as root, the following permissions are observed:
[-rw-rw-rw-] agent.port
[-rw-r--r--] lttng-sessiond.pid
When starting as user:
[-rw-rw----] agent.port
[-rw-rw-r--] lttng-sessiond.pid
Note that despite being created by the same function,
`utils_create_pid_file`, the permissions are not the same.
Cause
=====
`get_wait_shm` manipulates the umask and does not restore it, thus
influencing the outcome of following file creations that don't enforce
specific permissions (using chmod).
Also `fopen` defaults to mode `0666 & ~umask`, thus resulting in
unnecessarily lax permissions when the session daemon is started as a
non-privileged user (umask = 0002, most of the time).
Solution
========
Mimic other call sites of umask(), modify then revert the umask.
Open the pid and agent port files as 0644 letting the umask to do its
job as necessary for those files.
Remove unnecessary umask() usage when chmod is directly used.
Known drawbacks
===============
Use of umask in a multi-threaded process is not recommended. Still our
current usage is limited and mostly happens during the initialization
phase. The usage of umask() is required for the `wait_shm` since on
FreeBSD it is not possible to chmod an shm file descriptor. The default
umask would interfere here.
Discussion
==========
The usage in run-as is valid even when in no-clone mode (valgrind) since
it is the sole user of umask() following the initialization phase. When
spawned as a separate process the clearing of umask is totally valid
even if it is not ideal since we are ignoring any umask set by the user.
It seems like the current usage is the lesser evil here.
Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: Ie224d254714fff05f4bced471ebfa8f19eede26a
static int create_client_sock(void)
{
int ret, client_sock;
static int create_client_sock(void)
{
int ret, client_sock;
- const mode_t old_umask = umask(0);
/* Create client tool unix socket */
client_sock = lttcomm_create_unix_sock(
/* Create client tool unix socket */
client_sock = lttcomm_create_unix_sock(
DBG("Created client socket (fd = %i)", client_sock);
ret = client_sock;
end:
DBG("Created client socket (fd = %i)", client_sock);
ret = client_sock;
end:
{
int ret = 0;
int apps_sock;
{
int ret = 0;
int apps_sock;
- const mode_t old_umask = umask(0);
/* Create the application unix socket */
apps_sock = lttcomm_create_unix_sock(
/* Create the application unix socket */
apps_sock = lttcomm_create_unix_sock(
DBG3("Session daemon application socket created (fd = %d) ", apps_sock);
ret = apps_sock;
end:
DBG3("Session daemon application socket created (fd = %d) ", apps_sock);
ret = apps_sock;
end:
return ret;
error_close_socket:
if (close(apps_sock)) {
return ret;
error_close_socket:
if (close(apps_sock)) {
- * Using fork to set umask in the child process (not multi-thread safe). We
- * deal with the shm_open vs ftruncate race (happening when the sessiond owns
+ * We deal with the shm_open vs ftruncate race (happening when the sessiond owns
* the shm and does not let everybody modify it, to ensure safety against
* shm_unlink) by simply letting the mmap fail and retrying after a few
* seconds. For global shm, everybody has rw access to it until the sessiond
* the shm and does not let everybody modify it, to ensure safety against
* shm_unlink) by simply letting the mmap fail and retrying after a few
* seconds. For global shm, everybody has rw access to it until the sessiond
static int get_wait_shm(char *shm_path, size_t mmap_size, int global)
{
int wait_shm_fd, ret;
static int get_wait_shm(char *shm_path, size_t mmap_size, int global)
{
int wait_shm_fd, ret;
mode |= S_IROTH | S_IWOTH;
}
mode |= S_IROTH | S_IWOTH;
}
- /*
- * We're alone in a child process, so we can modify the process-wide
- * umask.
- */
- umask(~mode);
+ old_mode = umask(~mode);
/*
* Try creating shm (or get rw access). We don't do an exclusive open,
/*
* Try creating shm (or get rw access). We don't do an exclusive open,
if (ret < 0) {
PERROR("Failed to truncate \"wait\" shared memory object: fd = %d, size = %zu",
wait_shm_fd, mmap_size);
if (ret < 0) {
PERROR("Failed to truncate \"wait\" shared memory object: fd = %d, size = %zu",
wait_shm_fd, mmap_size);
if (ret < 0) {
PERROR("Failed to set ownership of \"wait\" shared memory object: fd = %d, owner = 0, group = 0",
wait_shm_fd);
if (ret < 0) {
PERROR("Failed to set ownership of \"wait\" shared memory object: fd = %d, owner = 0, group = 0",
wait_shm_fd);
}
/*
* If global session daemon, any application can
}
/*
* If global session daemon, any application can
if (ret < 0) {
PERROR("Failed to set the mode of the \"wait\" shared memory object: fd = %d, mode = %d",
wait_shm_fd, mode);
if (ret < 0) {
PERROR("Failed to set the mode of the \"wait\" shared memory object: fd = %d, mode = %d",
wait_shm_fd, mode);
}
} else {
ret = fchown(wait_shm_fd, getuid(), getgid());
if (ret < 0) {
PERROR("Failed to set ownership of \"wait\" shared memory object: fd = %d, owner = %d, group = %d",
wait_shm_fd, getuid(), getgid());
}
} else {
ret = fchown(wait_shm_fd, getuid(), getgid());
if (ret < 0) {
PERROR("Failed to set ownership of \"wait\" shared memory object: fd = %d, owner = %d, group = %d",
wait_shm_fd, getuid(), getgid());
shm_path, mmap_size, global ? "true" : "false",
wait_shm_fd);
shm_path, mmap_size, global ? "true" : "false",
wait_shm_fd);
+end:
+ (void) umask(old_mode);
return wait_shm_fd;
error:
return wait_shm_fd;
error:
- DBG("Failed to open shared memory file descriptor: path = '%s', mmap_size = %zu, global = %s",
- shm_path, mmap_size, global ? "true" : "false");
+ DBG("Failing to get the wait shm fd");
+ if (wait_shm_fd >= 0) {
+ if (close(wait_shm_fd)) {
+ PERROR("Failed to close wait shm file descriptor during error handling");
+ }
+ }
+ wait_shm_fd = -1;
+ goto end;
LTTNG_HIDDEN
int utils_create_pid_file(pid_t pid, const char *filepath)
{
LTTNG_HIDDEN
int utils_create_pid_file(pid_t pid, const char *filepath)
{
+ int ret, fd = -1;
+ FILE *fp = NULL;
- fp = fopen(filepath, "w");
+ fd = open(filepath, O_CREAT | O_WRONLY, S_IRUSR |S_IWUSR | S_IRGRP | S_IROTH);
+ if (fd < 0) {
+ PERROR("open file %s", filepath);
+ ret = -1;
+ goto error;
+ }
+
+ fp = fdopen(fd, "w");
- PERROR("open pid file %s", filepath);
+ PERROR("fdopen file %s", filepath);
goto error;
}
ret = fprintf(fp, "%d\n", (int) pid);
if (ret < 0) {
goto error;
}
ret = fprintf(fp, "%d\n", (int) pid);
if (ret < 0) {
- PERROR("fprintf pid file");
+ PERROR("fprintf file %s", filepath);
+ ret = -1;
- if (fclose(fp)) {
- PERROR("fclose");
- }
- DBG("Pid %d written in file %s", (int) pid, filepath);
+ DBG("'%d' written in file %s", (int) pid, filepath);
+ if (fp && fclose(fp)) {
+ PERROR("fclose file %s", filepath);
+ }