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Check for SVR4-style struct psinfo.pr_ttydev and use that to determine

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the tty if std{in,out,err} are not ttys.
This commit is contained in:
Todd C. Miller
2012-04-10 15:53:41 -04:00
parent 2e59eafba6
commit 11f13be0dd
4 changed files with 170 additions and 82 deletions
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89
src/ttyname.c
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@@ -16,6 +16,12 @@
#include <config.h>
/* Large files not supported by procfs.h */
#if defined(HAVE_PROCFS_H) || defined(HAVE_SYS_PROCFS_H)
# undef _FILE_OFFSET_BITS
# undef _LARGE_FILES
#endif
#include <sys/types.h>
#include <sys/param.h>
#include <sys/stat.h>
@@ -51,6 +57,11 @@
# include <sys/sysctl.h>
# include <sys/user.h>
#endif
#if defined(HAVE_PROCFS_H)
# include <procfs.h>
#elif defined(HAVE_SYS_PROCFS_H)
# include <sys/procfs.h>
#endif
#include "sudo.h"
@@ -79,7 +90,7 @@
# define sudo_kp_namelen 4
#endif
#ifdef sudo_kp_tdev
#if defined(sudo_kp_tdev)
/*
* Return a string from ttyname() containing the tty to which the process is
* attached or NULL if there is no tty associated with the process (or its
@@ -145,13 +156,59 @@ get_process_ttyname(void)
debug_return_str(tty);
}
#elif defined(HAVE_STRUCT_PSINFO_PR_TTYDEV)
/*
* Return a string from ttyname() containing the tty to which the process is
* attached or NULL if there is no tty associated with the process (or its
* parent). First tries std{in,out,err} then falls back to our /proc entry,
* or our parent's if that doesn't work.
*/
char *
get_process_ttyname(void)
{
char path[PATH_MAX], *tty = NULL;
struct stat sb;
struct psinfo psinfo;
ssize_t nread;
int i, fd;
debug_decl(get_process_ttyname, SUDO_DEBUG_UTIL)
if ((tty = ttyname(STDIN_FILENO)) == NULL &&
(tty = ttyname(STDOUT_FILENO)) == NULL &&
(tty = ttyname(STDERR_FILENO)) == NULL) {
/*
* No tty hooked up to std{in,out,err}, check /proc.
* We try to map pr_ttydev in psinfo to /dev/pts/N
*/
for (i = 0; tty == NULL && i < 2; i++) {
snprintf(path, sizeof(path), "/proc/%u/psinfo",
i ? (unsigned int)getppid() : (unsigned int)getpid());
if ((fd = open(path, O_RDONLY, 0)) == -1)
continue;
nread = read(fd, &psinfo, sizeof(psinfo));
close(fd);
if (nread != (ssize_t)sizeof(psinfo) || psinfo.pr_ttydev == PRNODEV)
continue;
(void)snprintf(path, sizeof(path), "%spts/%u", _PATH_DEV,
(unsigned int)minor(psinfo.pr_ttydev));
if (stat(path, &sb) == 0 && sb.st_rdev == psinfo.pr_ttydev) {
fd = open(path, O_RDONLY|O_NOCTTY|O_NONBLOCK, 0);
if (fd != -1) {
tty = ttyname(fd);
close(fd);
}
}
}
}
debug_return_str(estrdup(tty));
}
#else
/*
* Return a string from ttyname() containing the tty to which the process is
* attached or NULL if there is no tty associated with the process (or its
* parent). First tries std{in,out,err} then falls back to the parent's /proc
* entry. We could try following the parent all the way to pid 1 but
* /proc/%d/status is system-specific (text on Linux, a struct on SVR4).
* parent). First tries std{in,out,err} then falls back to our parent's /proc
* entry.
*/
char *
get_process_ttyname(void)
@@ -168,26 +225,8 @@ get_process_ttyname(void)
/* No tty for child, check the parent via /proc. */
ppid = getppid();
for (i = STDIN_FILENO; i <= STDERR_FILENO && tty == NULL; i++) {
snprintf(path, sizeof(path), "/proc/%d/fd/%d", (int)ppid, i);
if (stat(path, &sb) != 0)
continue;
/*
* SVR4-style /proc doesn't allow /proc/pid/fd/[0-2]
* to be used if it is a device and sets the mode to 0000.
* Linux-style /proc uses a link to the actual tty.
*/
if (S_ISCHR(sb.st_mode) &&
(sb.st_mode & (S_IRWXU|S_IRWXG|S_IRWXO)) == 0) {
/*
* We can't open it but maybe we can determine
* the pts device using the minor number.
*/
dev_t fd_dev = sb.st_rdev;
(void)snprintf(path, sizeof(path), "/dev/pts/%u",
(unsigned int)minor(sb.st_rdev));
if (stat(path, &sb) != 0 || sb.st_rdev != fd_dev)
continue;
}
snprintf(path, sizeof(path), "/proc/%u/fd/%d",
(unsigned int)ppid, i);
fd = open(path, O_RDONLY|O_NOCTTY|O_NONBLOCK, 0);
if (fd != -1) {
tty = ttyname(fd);
@@ -198,4 +237,4 @@ get_process_ttyname(void)
debug_return_str(estrdup(tty));
}
#endif /* sudo_kp_tdev */
#endif /* !sudo_kp_tdev && !HAVE_STRUCT_PSINFO_PR_TTYDEV */