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[pty] Split chfunc into functions in steps

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- start a new session
- obtain the new controlling terminal
- drop privileges
- finally, `exec`
This commit is contained in:
Nobuyoshi Nakada 2024-04-08 11:55:26 +09:00
parent 88355da673
commit 0bc71828b5
1 changed files with 43 additions and 12 deletions
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55
ext/pty/pty.c
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@ -92,9 +92,13 @@ struct pty_info {
static void getDevice(int*, int*, char [DEVICELEN], int); static void getDevice(int*, int*, char [DEVICELEN], int);
static int start_new_session(char *errbuf, size_t errbuf_len);
static int obtain_ctty(int master, int slave, const char *slavename, char *errbuf, size_t errbuf_len);
static int drop_privilige(char *errbuf, size_t errbuf_len);
struct child_info { struct child_info {
int master, slave; int master, slave;
char *slavename; const char *slavename;
VALUE execarg_obj; VALUE execarg_obj;
struct rb_execarg *eargp; struct rb_execarg *eargp;
}; };
@ -102,18 +106,34 @@ struct child_info {
static int static int
chfunc(void *data, char *errbuf, size_t errbuf_len) chfunc(void *data, char *errbuf, size_t errbuf_len)
{ {
struct child_info *carg = data; const struct child_info *carg = data;
int master = carg->master; int master = carg->master;
int slave = carg->slave; int slave = carg->slave;
const char *slavename = carg->slavename;
if (start_new_session(errbuf, errbuf_len))
return -1;
if (obtain_ctty(master, slave, slavename, errbuf, errbuf_len))
return -1;
if (drop_privilige(errbuf, errbuf_len))
return -1;
return rb_exec_async_signal_safe(carg->eargp, errbuf, errbuf_len);
}
#define ERROR_EXIT(str) do { \ #define ERROR_EXIT(str) do { \
strlcpy(errbuf, (str), errbuf_len); \ strlcpy(errbuf, (str), errbuf_len); \
return -1; \ return -1; \
} while (0) } while (0)
/* /*
* Set free from process group and controlling terminal * Set free from process group and controlling terminal
*/ */
static int
start_new_session(char *errbuf, size_t errbuf_len)
{
#ifdef HAVE_SETSID #ifdef HAVE_SETSID
(void) setsid(); (void) setsid();
#else /* HAS_SETSID */ #else /* HAS_SETSID */
@ -135,17 +155,22 @@ chfunc(void *data, char *errbuf, size_t errbuf_len)
# endif /* SETPGRP_VOID */ # endif /* SETPGRP_VOID */
# endif /* HAVE_SETPGRP */ # endif /* HAVE_SETPGRP */
#endif /* HAS_SETSID */ #endif /* HAS_SETSID */
return 0;
}
/* /*
* obtain new controlling terminal * obtain new controlling terminal
*/ */
static int
obtain_ctty(int master, int slave, const char *slavename, char *errbuf, size_t errbuf_len)
{
#if defined(TIOCSCTTY) #if defined(TIOCSCTTY)
close(master); close(master);
(void) ioctl(slave, TIOCSCTTY, (char *)0); (void) ioctl(slave, TIOCSCTTY, (char *)0);
/* errors ignored for sun */ /* errors ignored for sun */
#else #else
close(slave); close(slave);
slave = rb_cloexec_open(carg->slavename, O_RDWR, 0); slave = rb_cloexec_open(slavename, O_RDWR, 0);
if (slave < 0) { if (slave < 0) {
ERROR_EXIT("open: pty slave"); ERROR_EXIT("open: pty slave");
} }
@ -156,14 +181,20 @@ chfunc(void *data, char *errbuf, size_t errbuf_len)
dup2(slave,1); dup2(slave,1);
dup2(slave,2); dup2(slave,2);
if (slave < 0 || slave > 2) (void)!close(slave); if (slave < 0 || slave > 2) (void)!close(slave);
return 0;
}
static int
drop_privilige(char *errbuf, size_t errbuf_len)
{
#if defined(HAVE_SETEUID) || defined(HAVE_SETREUID) || defined(HAVE_SETRESUID) #if defined(HAVE_SETEUID) || defined(HAVE_SETREUID) || defined(HAVE_SETRESUID)
if (seteuid(getuid())) ERROR_EXIT("seteuid()"); if (seteuid(getuid())) ERROR_EXIT("seteuid()");
#endif #endif
return 0;
return rb_exec_async_signal_safe(carg->eargp, errbuf, sizeof(errbuf_len));
#undef ERROR_EXIT
} }
#undef ERROR_EXIT
static void static void
establishShell(int argc, VALUE *argv, struct pty_info *info, establishShell(int argc, VALUE *argv, struct pty_info *info,
char SlaveName[DEVICELEN]) char SlaveName[DEVICELEN])