diff options
Diffstat (limited to 'dbutil.c')
| -rw-r--r-- | dbutil.c | 156 |
1 files changed, 153 insertions, 3 deletions
@@ -146,7 +146,7 @@ void dropbear_trace(const char* format, ...) { } va_start(param, format); - fprintf(stderr, "TRACE: "); + fprintf(stderr, "TRACE (%d): ", getpid()); vfprintf(stderr, format, param); fprintf(stderr, "\n"); va_end(param); @@ -338,9 +338,10 @@ int connect_remote(const char* remotehost, const char* remoteport, if (err) { if (errstring != NULL && *errstring == NULL) { int len; - len = 20 + strlen(gai_strerror(err)); + len = 100 + strlen(gai_strerror(err)); *errstring = (char*)m_malloc(len); - snprintf(*errstring, len, "Error resolving: %s", gai_strerror(err)); + snprintf(*errstring, len, "Error resolving '%s' port '%s'. %s", + remotehost, remoteport, gai_strerror(err)); } TRACE(("Error resolving: %s", gai_strerror(err))) return -1; @@ -398,6 +399,141 @@ int connect_remote(const char* remotehost, const char* remoteport, return sock; } +/* Sets up a pipe for a, returning three non-blocking file descriptors + * and the pid. exec_fn is the function that will actually execute the child process, + * it will be run after the child has fork()ed, and is passed exec_data. + * If ret_errfd == NULL then stderr will not be captured. + * ret_pid can be passed as NULL to discard the pid. */ +int spawn_command(void(*exec_fn)(void *user_data), void *exec_data, + int *ret_writefd, int *ret_readfd, int *ret_errfd, pid_t *ret_pid) { + int infds[2]; + int outfds[2]; + int errfds[2]; + pid_t pid; + + const int FDIN = 0; + const int FDOUT = 1; + + /* redirect stdin/stdout/stderr */ + if (pipe(infds) != 0) { + return DROPBEAR_FAILURE; + } + if (pipe(outfds) != 0) { + return DROPBEAR_FAILURE; + } + if (ret_errfd && pipe(errfds) != 0) { + return DROPBEAR_FAILURE; + } + +#ifdef __uClinux__ + pid = vfork(); +#else + pid = fork(); +#endif + + if (pid < 0) { + return DROPBEAR_FAILURE; + } + + if (!pid) { + /* child */ + + TRACE(("back to normal sigchld")) + /* Revert to normal sigchld handling */ + if (signal(SIGCHLD, SIG_DFL) == SIG_ERR) { + dropbear_exit("signal() error"); + } + + /* redirect stdin/stdout */ + + if ((dup2(infds[FDIN], STDIN_FILENO) < 0) || + (dup2(outfds[FDOUT], STDOUT_FILENO) < 0) || + (ret_errfd && dup2(errfds[FDOUT], STDERR_FILENO) < 0)) { + TRACE(("leave noptycommand: error redirecting FDs")) + dropbear_exit("child dup2() failure"); + } + + close(infds[FDOUT]); + close(infds[FDIN]); + close(outfds[FDIN]); + close(outfds[FDOUT]); + if (ret_errfd) + { + close(errfds[FDIN]); + close(errfds[FDOUT]); + } + + exec_fn(exec_data); + /* not reached */ + return DROPBEAR_FAILURE; + } else { + /* parent */ + close(infds[FDIN]); + close(outfds[FDOUT]); + + setnonblocking(outfds[FDIN]); + setnonblocking(infds[FDOUT]); + + if (ret_errfd) { + close(errfds[FDOUT]); + setnonblocking(errfds[FDIN]); + } + + if (ret_pid) { + *ret_pid = pid; + } + + *ret_writefd = infds[FDOUT]; + *ret_readfd = outfds[FDIN]; + if (ret_errfd) { + *ret_errfd = errfds[FDIN]; + } + return DROPBEAR_SUCCESS; + } +} + +/* Runs a command with "sh -c". Will close FDs (except stdin/stdout/stderr) and + * re-enabled SIGPIPE. If cmd is NULL, will run a login shell. + */ +void run_shell_command(const char* cmd, unsigned int maxfd, char* usershell) { + char * argv[4]; + char * baseshell = NULL; + unsigned int i; + + baseshell = basename(usershell); + + if (cmd != NULL) { + argv[0] = baseshell; + } else { + /* a login shell should be "-bash" for "/bin/bash" etc */ + int len = strlen(baseshell) + 2; /* 2 for "-" */ + argv[0] = (char*)m_malloc(len); + snprintf(argv[0], len, "-%s", baseshell); + } + + if (cmd != NULL) { + argv[1] = "-c"; + argv[2] = (char*)cmd; + argv[3] = NULL; + } else { + /* construct a shell of the form "-bash" etc */ + argv[1] = NULL; + } + + /* Re-enable SIGPIPE for the executed process */ + if (signal(SIGPIPE, SIG_DFL) == SIG_ERR) { + dropbear_exit("signal() error"); + } + + /* close file descriptors except stdin/stdout/stderr + * Need to be sure FDs are closed here to avoid reading files as root */ + for (i = 3; i <= maxfd; i++) { + m_close(i); + } + + execv(usershell, argv); +} + /* Return a string representation of the socket address passed. The return * value is allocated with malloc() */ unsigned char * getaddrstring(struct sockaddr_storage* addr, int withport) { @@ -708,3 +844,17 @@ void disallow_core() { lim.rlim_cur = lim.rlim_max = 0; setrlimit(RLIMIT_CORE, &lim); } + +/* Returns DROPBEAR_SUCCESS or DROPBEAR_FAILURE, with the result in *val */ +int m_str_to_uint(const char* str, unsigned int *val) { + errno = 0; + *val = strtoul(str, NULL, 10); + /* The c99 spec doesn't actually seem to define EINVAL, but most platforms + * I've looked at mention it in their manpage */ + if ((*val == 0 && errno == EINVAL) + || (*val == ULONG_MAX && errno == ERANGE)) { + return DROPBEAR_FAILURE; + } else { + return DROPBEAR_SUCCESS; + } +} |