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charon-tkm: charon: Avoid potential TOCTOU issues when accessing/writing PID file

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Same as the previous commit.
This commit is contained in:
Tobias Brunner
2026-07-24 08:47:35 +02:00
parent 18a104657e
commit d19591edda
1 changed files with 52 additions and 34 deletions
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src/charon-tkm/src/charon-tkm.c
+52 -34
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@@ -174,23 +174,35 @@ static bool lookup_uid_gid()
static bool check_pidfile()
{
struct stat stb;
int fd, flags = 0;
if (stat(pidfile_name, &stb) == 0)
#ifndef WIN32
flags |= O_NOFOLLOW;
#endif
fd = open(pidfile_name, O_RDONLY | flags);
if (fd != -1)
{
pidfile = fopen(pidfile_name, "r");
if (pidfile)
if (fstat(fd, &stb) == 0 && S_ISREG(stb.st_mode))
{
char buf[64];
pid_t pid = 0;
memset(buf, 0, sizeof(buf));
if (fread(buf, 1, sizeof(buf), pidfile))
pidfile = fdopen(fd, "r");
if (pidfile)
{
buf[sizeof(buf) - 1] = '\0';
pid = atoi(buf);
memset(buf, 0, sizeof(buf));
if (fread(buf, 1, sizeof(buf), pidfile))
{
buf[sizeof(buf) - 1] = '\0';
pid = atoi(buf);
}
fclose(pidfile);
pidfile = NULL;
}
else
{
close(fd);
}
fclose(pidfile);
pidfile = NULL;
if (pid && pid != getpid() && kill(pid, 0) == 0)
{
DBG1(DBG_DMN, "%s already running ('%s' exists)", dmn_name,
@@ -198,39 +210,45 @@ static bool check_pidfile()
return TRUE;
}
}
else
{
close(fd);
}
}
if (fd != -1 || errno != ENOENT)
{
DBG1(DBG_DMN, "removing pidfile '%s', process not running", pidfile_name);
unlink(pidfile_name);
}
/* create new pidfile */
pidfile = fopen(pidfile_name, "w");
if (pidfile)
{
int fd;
fd = fileno(pidfile);
if (fd == -1)
{
DBG1(DBG_DMN, "unable to determine fd for '%s'", pidfile_name);
return TRUE;
}
if (fcntl(fd, F_SETFD, FD_CLOEXEC) == -1)
{
DBG1(DBG_LIB, "setting FD_CLOEXEC for '%s' failed: %s",
pidfile_name, strerror(errno));
}
ignore_result(fchown(fd,
lib->caps->get_uid(lib->caps),
lib->caps->get_gid(lib->caps)));
fprintf(pidfile, "%d\n", getpid());
fflush(pidfile);
return FALSE;
}
else
/* create new pidfile securely without following symlinks */
fd = open(pidfile_name, O_CREAT | O_EXCL | O_WRONLY, 0644);
if (fd == -1)
{
DBG1(DBG_DMN, "unable to create pidfile '%s'", pidfile_name);
return TRUE;
}
if (fcntl(fd, F_SETFD, FD_CLOEXEC) == -1)
{
DBG1(DBG_LIB, "setting FD_CLOEXEC for '%s' failed: %s",
pidfile_name, strerror(errno));
}
ignore_result(fchown(fd,
lib->caps->get_uid(lib->caps),
lib->caps->get_gid(lib->caps)));
pidfile = fdopen(fd, "w");
if (!pidfile)
{
DBG1(DBG_DMN, "unable to open pidfile '%s': %s", pidfile_name,
strerror(errno));
close(fd);
unlink(pidfile_name);
return TRUE;
}
fprintf(pidfile, "%d\n", getpid());
fflush(pidfile);
return FALSE;
}
/**