diff options
Diffstat (limited to 'sysdeps/unix/grantpt.c')
| -rw-r--r-- | sysdeps/unix/grantpt.c | 150 |
1 files changed, 121 insertions, 29 deletions
diff --git a/sysdeps/unix/grantpt.c b/sysdeps/unix/grantpt.c index 5d33a515f1..d216baa476 100644 --- a/sysdeps/unix/grantpt.c +++ b/sysdeps/unix/grantpt.c @@ -17,65 +17,158 @@ write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ +#include <assert.h> #include <errno.h> +#include <grp.h> +#include <limits.h> #include <stdlib.h> -#include <unistd.h> +#include <string.h> #include <sys/resource.h> #include <sys/stat.h> #include <sys/types.h> #include <sys/wait.h> +#include <unistd.h> -#include <assert.h> +#include "pty-private.h" + + +/* Return the result of ptsname_r in the buffer pointed to by PTS, + which should be of length BUF_LEN. If it is too long to fit in + this buffer, a sufficiently long buffer is allocated using malloc, + and returned in PTS. 0 is returned upon success, -1 otherwise. */ +static int +pts_name (int fd, char **pts, size_t buf_len) +{ + int rv; + char *buf = *pts; + + for (;;) + { + char *new_buf; + + if (buf_len) + { + rv = ptsname_r (fd, buf, buf_len); + + if (rv != 0 || memchr (buf, '\0', buf_len)) + /* We either got an error, or we succeeded and the + returned name fit in the buffer. */ + break; + + /* Try again with a longer buffer. */ + buf_len += buf_len; /* Double it */ + } + else + /* No initial buffer; start out by mallocing one. */ + buf_len = 128; /* First time guess. */ -#include "pty-internal.h" + if (buf != *pts) + /* We've already malloced another buffer at least once. */ + new_buf = realloc (buf, buf_len); + else + new_buf = malloc (buf_len); + if (! new_buf) + { + rv = -1; + __set_errno (ENOMEM); + break; + } + buf = new_buf; + } -/* Given a fd on a master pseudoterminal, chown the file associated - with the slave to the calling process, and set its group and - mode appropriately. Note that this is an unprivileged operation. */ + if (rv == 0) + *pts = buf; /* Return buffer to the user. */ + else if (buf != *pts) + free (buf); /* Free what we malloced when returning an error. */ -/* This "generic Unix" implementation works because we provide the program - /usr/libexec/pt_chown, and it only depends on ptsname() working. */ -static const char helper[] = LIBEXECDIR "/pt_chown"; -static const char *const argv[] = { "pt_chown", NULL }; + return rv; +} +/* Change the ownership and access permission of the slave pseudo + terminal associated with the master pseudo terminal specified + by FD. */ int -grantpt (fd) - int fd; +grantpt (int fd) { +#ifdef PATH_MAX + char _buf[PATH_MAX]; +#else + char _buf[512]; +#endif + char *buf = _buf; struct stat st; - int w, pid; - char namebuf[PTYNAMELEN]; - - /* Some systems do it for us. */ - if (__ptsname_r (fd, namebuf, PTYNAMELEN) != 0) + char *grtmpbuf; + struct group grbuf; + size_t grbuflen = __sysconf (_SC_GETGR_R_SIZE_MAX); + struct group *p; + uid_t uid; + gid_t gid; + pid_t pid; + + if (pts_name (fd, &buf, sizeof (_buf))) return -1; - if (__xstat (_STAT_VER, namebuf, &st) != 0) + + if (__stat (buf, &st) < 0) return -1; - if (st.st_uid == __getuid ()) - return 0; + /* Make sure that we own the device. */ + uid = __getuid (); + if (st.st_uid != uid) + { + if (__chown (buf, uid, st.st_gid) < 0) + goto helper; + } + + /* Get the group ID of the special `tty' group. */ + if (grbuflen == -1) + /* `sysconf' does not support _SC_GETGR_R_SIZE_MAX. + Try a moderate value. */ + grbuflen = 1024; + grtmpbuf = (char *) __alloca (grbuflen); + getgrnam_r (TTY_GROUP, &grbuf, grtmpbuf, grbuflen, &p); + gid = p ? p->gr_gid : __getgid (); + + /* Make sure the group of the device is that special group. */ + if (st.st_gid != gid) + { + if (__chown (buf, uid, gid) < 0) + goto helper; + } + + /* Make sure the permission mode is set to readable and writable by + the owner, and writable by the group. */ + if ((st.st_mode & ACCESSPERMS) != (S_IRUSR|S_IWUSR|S_IWGRP)) + { + if (__chmod (buf, S_IRUSR|S_IWUSR|S_IWGRP) < 0) + goto helper; + } + + return 0; - /* We have to do it in user space. */ + /* We have to use the helper program. */ + helper: pid = __fork (); if (pid == -1) return -1; else if (pid == 0) { - /* Disable core dumps in the child. */ - struct rlimit off = { 0, 0 }; - setrlimit (RLIMIT_CORE, &off); + /* Disable core dumps. */ + struct rlimit rl = { 0, 0 }; + setrlimit (RLIMIT_CORE, &rl); - /* The helper does its thing on fd PTY_FD. */ - if (fd != PTY_FD) - if (__dup2 (fd, PTY_FD) == -1) + /* We pase the master pseudo terminal as file descriptor PTY_FILENO. */ + if (fd != PTY_FILENO) + if (__dup2 (fd, PTY_FILENO) < 0) _exit (FAIL_EBADF); - __execve (helper, (char *const *) argv, 0); + execle (_PATH_PT_CHOWN, basename (_PATH_PT_CHOWN), NULL, NULL); _exit (FAIL_EXEC); } else { + int w; + if (__waitpid (pid, &w, 0) == -1) return -1; if (!WIFEXITED (w)) @@ -106,6 +199,5 @@ grantpt (fd) } } - /* Success. */ return 0; } |