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Rototill code to determine the tty. For Linux, we now look up the

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tty device in /proc/pid/stat instead of trying to open /proc/pid/fd/[0-2].
The sudo_ttyname_dev() function maps the given device number to a
string.  On BSD, we can use devname().  On Solaris, _ttyname_dev()
does what we want.
TODO: write /dev/ traversal code for the generic sudo_ttyname_dev().
This commit is contained in:
Todd C. Miller
2012-04-11 14:48:08 -04:00
parent 271f3e2054
commit 83fc02bc97
4 changed files with 192 additions and 77 deletions
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234
src/ttyname.c
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@@ -51,6 +51,7 @@
#endif /* HAVE_UNISTD_H */
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#if defined(HAVE_STRUCT_KINFO_PROC_P_TDEV) || defined (HAVE_STRUCT_KINFO_PROC_KP_EPROC_E_TDEV) || defined(HAVE_STRUCT_KINFO_PROC2_P_TDEV)
# include <sys/sysctl.h>
#elif defined(HAVE_STRUCT_KINFO_PROC_KI_TDEV)
@@ -90,6 +91,86 @@
# define sudo_kp_namelen 4
#endif
#if defined(sudo_kp_tdev)
/*
* Like ttyname() but uses a dev_t instead of an open fd.
* Caller is responsible for freeing the returned string.
* The BSD version uses devname()
*/
static char *
sudo_ttyname_dev(dev_t tdev)
{
char *dev, *tty = NULL;
debug_decl(sudo_ttyname_dev, SUDO_DEBUG_UTIL)
/* Some versions of devname() return NULL on failure, others do not. */
dev = devname(tdev, S_IFCHR);
if (dev != NULL && *dev != '?' && *dev != '#') {
if (*dev != '/') {
/* devname() doesn't use the /dev/ prefix, add one... */
size_t len = sizeof(_PATH_DEV) + strlen(dev);
tty = emalloc(len);
strlcpy(tty, _PATH_DEV, len);
strlcat(tty, dev, len);
} else {
/* Should not happen but just in case... */
tty = estrdup(dev);
}
}
debug_return_str(tty);
}
#elif defined(HAVE__TTYNAME_DEV)
extern char *_ttyname_dev(dev_t rdev, char *buffer, size_t buflen);
/*
* Like ttyname() but uses a dev_t instead of an open fd.
* Caller is responsible for freeing the returned string.
* This version is just a wrapper around _ttyname_dev().
*/
static char *
sudo_ttyname_dev(dev_t tdev)
{
char buf[TTYNAME_MAX], *tty;
struct stat sb;
debug_decl(sudo_ttyname_dev, SUDO_DEBUG_UTIL)
/* Check if it is a pseudo-tty slave, falling back on _ttyname_dev() */
(void)snprintf(buf, sizeof(buf), "%spts/%u", _PATH_DEV,
(unsigned int)minor(tdev));
if (stat(buf, &sb) == 0 && sb.st_rdev == tdev) {
tty = buf;
} else {
tty = _ttyname_dev(tdev, buf, sizeof(buf));
}
debug_return_str(estrdup(tty));
}
#else
/*
* Like ttyname() but uses a dev_t instead of an open fd.
* Caller is responsible for freeing the returned string.
* Generic version.
*/
static char *
sudo_ttyname_dev(dev_t tdev)
{
char buf[PATH_MAX], *tty = NULL;
struct stat sb;
debug_decl(sudo_ttyname_dev, SUDO_DEBUG_UTIL)
/* First, check if it is a pseudo-tty slave. */
(void)snprintf(buf, sizeof(buf), "%spts/%u", _PATH_DEV,
(unsigned int)minor(tdev));
if (stat(buf, &sb) == 0 && sb.st_rdev == tdev) {
tty = buf;
} else {
/* XXX - fallback to scanning /dev/ */
}
debug_return_str(estrdup(tty));
}
#endif
#if defined(sudo_kp_tdev)
/*
* Return a string from ttyname() containing the tty to which the process is
@@ -123,21 +204,13 @@ get_process_ttyname(void)
rc = sysctl(mib, sudo_kp_namelen, ki_proc, &size, NULL, 0);
} while (rc == -1 && errno == ENOMEM);
if (rc != -1) {
char *dev = devname(ki_proc->sudo_kp_tdev, S_IFCHR);
/* Some versions of devname() return NULL, others do not. */
if (dev == NULL || *dev == '?' || *dev == '#') {
sudo_debug_printf(SUDO_DEBUG_WARN,
"unable to map device number %u to name",
ki_proc->sudo_kp_tdev);
} else if (*dev != '/') {
/* devname() doesn't use the /dev/ prefix, add one... */
size_t len = sizeof(_PATH_DEV) + strlen(dev);
tty = emalloc(len);
strlcpy(tty, _PATH_DEV, len);
strlcat(tty, dev, len);
} else {
/* Should not happen but just in case... */
tty = estrdup(dev);
if (ki_proc->sudo_kp_tdev != (dev_t)-1) {
tty = sudo_ttyname_dev(ki_proc->sudo_kp_tdev);
if (tty == NULL) {
sudo_debug_printf(SUDO_DEBUG_WARN,
"unable to map device number %u to name",
ki_proc->sudo_kp_tdev);
}
}
} else {
sudo_debug_printf(SUDO_DEBUG_WARN,
@@ -157,14 +230,11 @@ get_process_ttyname(void)
debug_return_str(tty);
}
#elif defined(HAVE_STRUCT_PSINFO_PR_TTYDEV)
# ifndef PRNODEV
# define PRNODEV ((dev_t)-1)
# endif
/*
* 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.
* parent). First tries /proc/pid/psinfo, then /proc/ppid/psinfo.
* Falls back on ttyname of std{in,out,err} if that fails.
*/
char *
get_process_ttyname(void)
@@ -176,68 +246,100 @@ get_process_ttyname(void)
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);
}
}
/* Try to determine the tty from pr_ttydev in /proc/pid/psinfo. */
for (i = 0; tty == NULL && i < 2; i++) {
(void)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 != (dev_t)-1) {
tty = sudo_ttyname_dev(psinfo.pr_ttydev);
}
}
debug_return_str(estrdup(tty));
/* If all else fails, fall back on ttyname(). */
if (tty == NULL) {
if ((tty = ttyname(STDIN_FILENO)) != NULL ||
(tty = ttyname(STDOUT_FILENO)) != NULL ||
(tty = ttyname(STDERR_FILENO)) != NULL)
tty = estrdup(tty);
}
debug_return_str(tty);
}
#else
#elif defined(__linux__)
/*
* 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 parent's /proc
* entry.
* parent). First tries field 7 in /proc/pid/stat, then /proc/ppid/stat.
* Falls back on ttyname of std{in,out,err} if that fails.
*/
char *
get_process_ttyname(void)
{
char path[PATH_MAX], *tty = NULL;
struct stat sb;
pid_t ppid;
int i, fd;
char *line = NULL, *tty = NULL;
size_t linesize = 0;
ssize_t len;
int i;
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 for child, check the parent via /proc. */
ppid = getppid();
for (i = STDIN_FILENO; i <= STDERR_FILENO && tty == NULL; i++) {
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);
close(fd);
/* Try to determine the tty from pr_ttydev in /proc/pid/psinfo. */
for (i = 0; tty == NULL && i < 2; i++) {
FILE *fp;
char path[PATH_MAX];
(void)snprintf(path, sizeof(path), "/proc/%u/stat",
i ? (unsigned int)getppid() : (unsigned int)getpid());
if ((fp = fopen(path, "r")) == NULL)
continue;
len = getline(&line, &linesize, fp);
fclose(fp);
if (len != -1) {
/* Field 7 is the tty dev (0 if no tty) */
char *cp = line;
int field = 1;
while (*cp != '\0') {
if (*cp++ == ' ') {
if (++field == 7) {
dev_t tdev = (dev_t)atoi(cp);
if (tdev > 0)
tty = sudo_ttyname_dev(tdev);
break;
}
}
}
}
}
efree(line);
/* If all else fails, fall back on ttyname(). */
if (tty == NULL) {
if ((tty = ttyname(STDIN_FILENO)) != NULL ||
(tty = ttyname(STDOUT_FILENO)) != NULL ||
(tty = ttyname(STDERR_FILENO)) != NULL)
tty = estrdup(tty);
}
debug_return_str(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.
* parent).
*/
char *
get_process_ttyname(void)
{
char *tty;
debug_decl(get_process_ttyname, SUDO_DEBUG_UTIL)
if ((tty = ttyname(STDIN_FILENO)) == NULL) {
if ((tty = ttyname(STDOUT_FILENO)) == NULL)
tty = ttyname(STDERR_FILENO);
}
debug_return_str(estrdup(tty));
}
#endif /* !sudo_kp_tdev && !HAVE_STRUCT_PSINFO_PR_TTYDEV */
#endif