diff options
Diffstat (limited to 'src/lib/process/restrict.c')
| -rw-r--r-- | src/lib/process/restrict.c | 136 |
1 files changed, 136 insertions, 0 deletions
diff --git a/src/lib/process/restrict.c b/src/lib/process/restrict.c index 85c04efbbf..bb44cc3d15 100644 --- a/src/lib/process/restrict.c +++ b/src/lib/process/restrict.c @@ -5,7 +5,17 @@ #include "orconfig.h" #include "lib/process/restrict.h" +#include "lib/intmath/cmp.h" #include "lib/log/torlog.h" +#include "lib/log/util_bug.h" +#include "lib/net/socket.h" + +#ifdef HAVE_SYS_MMAN_H +#include <sys/mman.h> +#endif +#include <errno.h> +#include <stdlib.h> +#include <string.h> /* We only use the linux prctl for now. There is no Win32 support; this may * also work on various BSD systems and Mac OS X - send testing feedback! @@ -142,3 +152,129 @@ tor_mlockall(void) return -1; #endif /* defined(HAVE_UNIX_MLOCKALL) */ } + +/** Number of extra file descriptors to keep in reserve beyond those that we + * tell Tor it's allowed to use. */ +#define ULIMIT_BUFFER 32 /* keep 32 extra fd's beyond ConnLimit_ */ + +/** Learn the maximum allowed number of file descriptors, and tell the + * system we want to use up to that number. (Some systems have a low soft + * limit, and let us set it higher.) We compute this by finding the largest + * number that we can use. + * + * If the limit is below the reserved file descriptor value (ULIMIT_BUFFER), + * return -1 and <b>max_out</b> is untouched. + * + * If we can't find a number greater than or equal to <b>limit</b>, then we + * fail by returning -1 and <b>max_out</b> is untouched. + * + * If we are unable to set the limit value because of setrlimit() failing, + * return 0 and <b>max_out</b> is set to the current maximum value returned + * by getrlimit(). + * + * Otherwise, return 0 and store the maximum we found inside <b>max_out</b> + * and set <b>max_sockets</b> with that value as well.*/ +int +set_max_file_descriptors(rlim_t limit, int *max_out) +{ + if (limit < ULIMIT_BUFFER) { + log_warn(LD_CONFIG, + "ConnLimit must be at least %d. Failing.", ULIMIT_BUFFER); + return -1; + } + + /* Define some maximum connections values for systems where we cannot + * automatically determine a limit. Re Cygwin, see + * http://archives.seul.org/or/talk/Aug-2006/msg00210.html + * For an iPhone, 9999 should work. For Windows and all other unknown + * systems we use 15000 as the default. */ +#ifndef HAVE_GETRLIMIT +#if defined(CYGWIN) || defined(__CYGWIN__) + const char *platform = "Cygwin"; + const unsigned long MAX_CONNECTIONS = 3200; +#elif defined(_WIN32) + const char *platform = "Windows"; + const unsigned long MAX_CONNECTIONS = 15000; +#else + const char *platform = "unknown platforms with no getrlimit()"; + const unsigned long MAX_CONNECTIONS = 15000; +#endif /* defined(CYGWIN) || defined(__CYGWIN__) || ... */ + log_fn(LOG_INFO, LD_NET, + "This platform is missing getrlimit(). Proceeding."); + if (limit > MAX_CONNECTIONS) { + log_warn(LD_CONFIG, + "We do not support more than %lu file descriptors " + "on %s. Tried to raise to %lu.", + (unsigned long)MAX_CONNECTIONS, platform, (unsigned long)limit); + return -1; + } + limit = MAX_CONNECTIONS; +#else /* !(!defined(HAVE_GETRLIMIT)) */ + struct rlimit rlim; + + if (getrlimit(RLIMIT_NOFILE, &rlim) != 0) { + log_warn(LD_NET, "Could not get maximum number of file descriptors: %s", + strerror(errno)); + return -1; + } + if (rlim.rlim_max < limit) { + log_warn(LD_CONFIG,"We need %lu file descriptors available, and we're " + "limited to %lu. Please change your ulimit -n.", + (unsigned long)limit, (unsigned long)rlim.rlim_max); + return -1; + } + + if (rlim.rlim_max > rlim.rlim_cur) { + log_info(LD_NET,"Raising max file descriptors from %lu to %lu.", + (unsigned long)rlim.rlim_cur, (unsigned long)rlim.rlim_max); + } + /* Set the current limit value so if the attempt to set the limit to the + * max fails at least we'll have a valid value of maximum sockets. */ + *max_out = (int)rlim.rlim_cur - ULIMIT_BUFFER; + set_max_sockets(*max_out); + rlim.rlim_cur = rlim.rlim_max; + + if (setrlimit(RLIMIT_NOFILE, &rlim) != 0) { + int couldnt_set = 1; + const int setrlimit_errno = errno; +#ifdef OPEN_MAX + uint64_t try_limit = OPEN_MAX - ULIMIT_BUFFER; + if (errno == EINVAL && try_limit < (uint64_t) rlim.rlim_cur) { + /* On some platforms, OPEN_MAX is the real limit, and getrlimit() is + * full of nasty lies. I'm looking at you, OSX 10.5.... */ + rlim.rlim_cur = MIN((rlim_t) try_limit, rlim.rlim_cur); + if (setrlimit(RLIMIT_NOFILE, &rlim) == 0) { + if (rlim.rlim_cur < (rlim_t)limit) { + log_warn(LD_CONFIG, "We are limited to %lu file descriptors by " + "OPEN_MAX (%lu), and ConnLimit is %lu. Changing " + "ConnLimit; sorry.", + (unsigned long)try_limit, (unsigned long)OPEN_MAX, + (unsigned long)limit); + } else { + log_info(LD_CONFIG, "Dropped connection limit to %lu based on " + "OPEN_MAX (%lu); Apparently, %lu was too high and rlimit " + "lied to us.", + (unsigned long)try_limit, (unsigned long)OPEN_MAX, + (unsigned long)rlim.rlim_max); + } + couldnt_set = 0; + } + } +#endif /* defined(OPEN_MAX) */ + if (couldnt_set) { + log_warn(LD_CONFIG,"Couldn't set maximum number of file descriptors: %s", + strerror(setrlimit_errno)); + } + } + /* leave some overhead for logs, etc, */ + limit = rlim.rlim_cur; +#endif /* !defined(HAVE_GETRLIMIT) */ + + if (limit > INT_MAX) + limit = INT_MAX; + tor_assert(max_out); + *max_out = (int)limit - ULIMIT_BUFFER; + set_max_sockets(*max_out); + + return 0; +} |