*************************************************/
/* Copyright (c) University of Cambridge 1995 - 2018 */
+/* Copyright (c) The Exim Maintainers 2020 - 2021 */
/* See the file NOTICE for conditions of use and distribution. */
/* Functions for writing log files. The code for maintaining datestamped
US"Negotiation failed for proxy configured host",
US"Authenticator 'other' failure",
US"target not supporting SMTPUTF8",
- US"",
+ US"host is local",
+ US"tainted filename",
US"Not time for routing",
US"Not time for local delivery",
Returns: a file descriptor, or < 0 on failure (errno set)
*/
-int
-log_create(uschar *name)
+static int
+log_open_already_exim(uschar * const name)
{
-int fd = Uopen(name,
-#ifdef O_CLOEXEC
- O_CLOEXEC |
-#endif
- O_CREAT|O_APPEND|O_WRONLY, LOG_MODE);
+int fd = -1;
+const int flags = O_WRONLY | O_APPEND | O_CREAT | O_NONBLOCK;
+
+if (geteuid() != exim_uid)
+ {
+ errno = EACCES;
+ return -1;
+ }
+
+fd = Uopen(name, flags, LOG_MODE);
/* If creation failed, attempt to build a log directory in case that is the
problem. */
DEBUG(D_any) debug_printf("%s log directory %s\n",
created ? "created" : "failed to create", name);
*lastslash = '/';
- if (created) fd = Uopen(name,
-#ifdef O_CLOEXEC
- O_CLOEXEC |
-#endif
- O_CREAT|O_APPEND|O_WRONLY, LOG_MODE);
+ if (created) fd = Uopen(name, flags, LOG_MODE);
}
return fd;
+/* Inspired by OpenSSH's mm_send_fd(). Thanks!
+Send fd over socketpair.
+Return: true iff good.
+*/
+
+static BOOL
+log_send_fd(const int sock, const int fd)
+{
+struct msghdr msg;
+union {
+ struct cmsghdr hdr;
+ char buf[CMSG_SPACE(sizeof(int))];
+} cmsgbuf;
+struct cmsghdr *cmsg;
+char ch = 'A';
+struct iovec vec = {.iov_base = &ch, .iov_len = 1};
+ssize_t n;
+
+memset(&msg, 0, sizeof(msg));
+memset(&cmsgbuf, 0, sizeof(cmsgbuf));
+msg.msg_control = &cmsgbuf.buf;
+msg.msg_controllen = sizeof(cmsgbuf.buf);
+
+cmsg = CMSG_FIRSTHDR(&msg);
+cmsg->cmsg_len = CMSG_LEN(sizeof(int));
+cmsg->cmsg_level = SOL_SOCKET;
+cmsg->cmsg_type = SCM_RIGHTS;
+*(int *)CMSG_DATA(cmsg) = fd;
+
+msg.msg_iov = &vec;
+msg.msg_iovlen = 1;
+
+while ((n = sendmsg(sock, &msg, 0)) == -1 && errno == EINTR);
+return n == 1;
+}
+
+/* Inspired by OpenSSH's mm_receive_fd(). Thanks!
+Return fd passed over socketpair, or -1 on error.
+*/
+
+static int
+log_recv_fd(const int sock)
+{
+struct msghdr msg;
+union {
+ struct cmsghdr hdr;
+ char buf[CMSG_SPACE(sizeof(int))];
+} cmsgbuf;
+struct cmsghdr *cmsg;
+char ch = '\0';
+struct iovec vec = {.iov_base = &ch, .iov_len = 1};
+ssize_t n;
+int fd;
+
+memset(&msg, 0, sizeof(msg));
+msg.msg_iov = &vec;
+msg.msg_iovlen = 1;
+
+memset(&cmsgbuf, 0, sizeof(cmsgbuf));
+msg.msg_control = &cmsgbuf.buf;
+msg.msg_controllen = sizeof(cmsgbuf.buf);
+
+while ((n = recvmsg(sock, &msg, 0)) == -1 && errno == EINTR) ;
+if (n != 1 || ch != 'A') return -1;
+
+if (!(cmsg = CMSG_FIRSTHDR(&msg))) return -1;
+if (cmsg->cmsg_type != SCM_RIGHTS) return -1;
+if ((fd = *(const int *)CMSG_DATA(cmsg)) < 0) return -1;
+return fd;
+}
+
+
+
/*************************************************
* Create a log file as the exim user *
*************************************************/
*/
int
-log_create_as_exim(uschar *name)
+log_open_as_exim(uschar * const name)
{
-pid_t pid = exim_fork(US"logfile-create");
-int status = 1;
int fd = -1;
+const uid_t euid = geteuid();
-/* In the subprocess, change uid/gid and do the creation. Return 0 from the
-subprocess on success. If we don't check for setuid failures, then the file
-can be created as root, so vulnerabilities which cause setuid to fail mean
-that the Exim user can use symlinks to cause a file to be opened/created as
-root. We always open for append, so can't nuke existing content but it would
-still be Rather Bad. */
-
-if (pid == 0)
+if (euid == exim_uid)
+ fd = log_open_already_exim(name);
+else if (euid == root_uid)
{
- if (setgid(exim_gid) < 0)
- die(US"exim: setgid for log-file creation failed, aborting",
- US"Unexpected log failure, please try later");
- if (setuid(exim_uid) < 0)
- die(US"exim: setuid for log-file creation failed, aborting",
- US"Unexpected log failure, please try later");
- _exit((log_create(name) < 0)? 1 : 0);
- }
-
-/* If we created a subprocess, wait for it. If it succeeded, try the open. */
+ int sock[2];
+ if (socketpair(AF_UNIX, SOCK_STREAM, 0, sock) == 0)
+ {
+ const pid_t pid = fork();
+ if (pid == 0)
+ {
+ (void)close(sock[0]);
+ if ( setgroups(1, &exim_gid) != 0
+ || setgid(exim_gid) != 0
+ || setuid(exim_uid) != 0
+
+ || getuid() != exim_uid || geteuid() != exim_uid
+ || getgid() != exim_gid || getegid() != exim_gid
+
+ || (fd = log_open_already_exim(name)) < 0
+ || !log_send_fd(sock[1], fd)
+ ) _exit(EXIT_FAILURE);
+ (void)close(sock[1]);
+ _exit(EXIT_SUCCESS);
+ }
-while (pid > 0 && waitpid(pid, &status, 0) != pid);
-if (status == 0) fd = Uopen(name,
-#ifdef O_CLOEXEC
- O_CLOEXEC |
-#endif
- O_APPEND|O_WRONLY, LOG_MODE);
+ (void)close(sock[1]);
+ if (pid > 0)
+ {
+ fd = log_recv_fd(sock[0]);
+ while (waitpid(pid, NULL, 0) == -1 && errno == EINTR);
+ }
+ (void)close(sock[0]);
+ }
+ }
-/* If we failed to create a subprocess, we are in a bad way. We return
-with fd still < 0, and errno set, letting the caller handle the error. */
+if (fd >= 0)
+ {
+ int flags;
+ flags = fcntl(fd, F_GETFD);
+ if (flags != -1) (void)fcntl(fd, F_SETFD, flags | FD_CLOEXEC);
+ flags = fcntl(fd, F_GETFL);
+ if (flags != -1) (void)fcntl(fd, F_SETFL, flags & ~O_NONBLOCK);
+ }
+else
+ errno = EACCES;
return fd;
}
ok = string_format(buffer, sizeof(buffer), CS file_path, log_names[type]);
-/* Save the name of the mainlog for rollover processing. Without a datestamp,
-it gets statted to see if it has been cycled. With a datestamp, the datestamp
-will be compared. The static slot for saving it is the same size as buffer,
-and the text has been checked above to fit, so this use of strcpy() is OK. */
-
-if (type == lt_main && string_datestamp_offset >= 0)
+switch (type)
{
- Ustrcpy(mainlog_name, buffer);
- mainlog_datestamp = mainlog_name + string_datestamp_offset;
- }
-
-/* Ditto for the reject log */
-
-else if (type == lt_reject && string_datestamp_offset >= 0)
- {
- Ustrcpy(rejectlog_name, buffer);
- rejectlog_datestamp = rejectlog_name + string_datestamp_offset;
- }
-
-/* and deal with the debug log (which keeps the datestamp, but does not
-update it) */
+ case lt_main:
+ /* Save the name of the mainlog for rollover processing. Without a datestamp,
+ it gets statted to see if it has been cycled. With a datestamp, the datestamp
+ will be compared. The static slot for saving it is the same size as buffer,
+ and the text has been checked above to fit, so this use of strcpy() is OK. */
+ Ustrcpy(mainlog_name, buffer);
+ if (string_datestamp_offset > 0)
+ mainlog_datestamp = mainlog_name + string_datestamp_offset;
+ break;
-else if (type == lt_debug)
- {
- Ustrcpy(debuglog_name, buffer);
- if (tag)
- {
- /* this won't change the offset of the datestamp */
- ok2 = string_format(buffer, sizeof(buffer), "%s%s",
- debuglog_name, tag);
- if (ok2)
- Ustrcpy(debuglog_name, buffer);
- }
- }
+ case lt_reject:
+ /* Ditto for the reject log */
+ Ustrcpy(rejectlog_name, buffer);
+ if (string_datestamp_offset > 0)
+ rejectlog_datestamp = rejectlog_name + string_datestamp_offset;
+ break;
-/* Remove any datestamp if this is the panic log. This is rare, so there's no
-need to optimize getting the datestamp length. We remove one non-alphanumeric
-char afterwards if at the start, otherwise one before. */
+ case lt_debug:
+ /* and deal with the debug log (which keeps the datestamp, but does not
+ update it) */
+ Ustrcpy(debuglog_name, buffer);
+ if (tag)
+ {
+ /* this won't change the offset of the datestamp */
+ ok2 = string_format(buffer, sizeof(buffer), "%s%s",
+ debuglog_name, tag);
+ if (ok2)
+ Ustrcpy(debuglog_name, buffer);
+ }
+ break;
-else if (string_datestamp_offset >= 0)
- {
- uschar * from = buffer + string_datestamp_offset;
- uschar * to = from + string_datestamp_length;
+ default:
+ /* Remove any datestamp if this is the panic log. This is rare, so there's no
+ need to optimize getting the datestamp length. We remove one non-alphanumeric
+ char afterwards if at the start, otherwise one before. */
+ if (string_datestamp_offset >= 0)
+ {
+ uschar * from = buffer + string_datestamp_offset;
+ uschar * to = from + string_datestamp_length;
- if (from == buffer || from[-1] == '/')
- {
- if (!isalnum(*to)) to++;
- }
- else
- if (!isalnum(from[-1])) from--;
+ if (from == buffer || from[-1] == '/')
+ {
+ if (!isalnum(*to)) to++;
+ }
+ else
+ if (!isalnum(from[-1])) from--;
- /* This copy is ok, because we know that to is a substring of from. But
- due to overlap we must use memmove() not Ustrcpy(). */
- memmove(from, to, Ustrlen(to)+1);
+ /* This copy is ok, because we know that to is a substring of from. But
+ due to overlap we must use memmove() not Ustrcpy(). */
+ memmove(from, to, Ustrlen(to)+1);
+ }
+ break;
}
/* If the file name is too long, it is an unrecoverable disaster */
die(US"exim: log file path too long: aborting",
US"Logging failure; please try later");
-/* We now have the file name. Try to open an existing file. After a successful
-open, arrange for automatic closure on exec(), and then return. */
-
-*fd = Uopen(buffer,
-#ifdef O_CLOEXEC
- O_CLOEXEC |
-#endif
- O_APPEND|O_WRONLY, LOG_MODE);
+/* We now have the file name. After a successful open, return. */
-if (*fd >= 0)
- {
-#ifndef O_CLOEXEC
- (void)fcntl(*fd, F_SETFD, fcntl(*fd, F_GETFD) | FD_CLOEXEC);
-#endif
+if ((*fd = log_open_as_exim(buffer)) >= 0)
return;
- }
-
-/* Open was not successful: try creating the file. If this is a root process,
-we must do the creating in a subprocess set to exim:exim in order to ensure
-that the file is created with the right ownership. Otherwise, there can be a
-race if another Exim process is trying to write to the log at the same time.
-The use of SIGUSR1 by the exiwhat utility can provoke a lot of simultaneous
-writing. */
euid = geteuid();
-/* If we are already running as the Exim user (even if that user is root),
-we can go ahead and create in the current process. */
-
-if (euid == exim_uid) *fd = log_create(buffer);
-
-/* Otherwise, if we are root, do the creation in an exim:exim subprocess. If we
-are neither exim nor root, creation is not attempted. */
-
-else if (euid == root_uid) *fd = log_create_as_exim(buffer);
-
-/* If we now have an open file, set the close-on-exec flag and return. */
-
-if (*fd >= 0)
- {
-#ifndef O_CLOEXEC
- (void)fcntl(*fd, F_SETFD, fcntl(*fd, F_GETFD) | FD_CLOEXEC);
-#endif
- return;
- }
-
/* Creation failed. There are some circumstances in which we get here when
the effective uid is not root or exim, which is the problem. (For example, a
non-setuid binary with log_arguments set, called in certain ways.) Rather than
"More than one path given in log_file_path: using %s", file_path);
}
+/* Optionally trigger debug */
+
+if (flags & LOG_PANIC && dtrigger_selector & BIT(DTi_panictrigger))
+ debug_trigger_fire();
+
/* If debugging, show all log entries, but don't show headers. Do it all
in one go so that it doesn't get split when multi-processing. */
if (f.disable_logging)
{
DEBUG(D_any) debug_printf("log writing disabled\n");
+ if ((flags & LOG_PANIC_DIE) == LOG_PANIC_DIE) exim_exit(EXIT_FAILURE);
return;
}
panic_recurseflag = FALSE;
if (panic_save_buffer)
- {
- int i = write(paniclogfd, panic_save_buffer, Ustrlen(panic_save_buffer));
- i = i; /* compiler quietening */
- }
+ (void) write(paniclogfd, panic_save_buffer, Ustrlen(panic_save_buffer));
written_len = write_to_fd_buf(paniclogfd, g->s, g->ptr);
if (written_len != g->ptr)
uschar *string, bit_table *options, int count, uschar *which, int flags)
{
uschar *errmsg;
-if (string == NULL) return;
+if (!string) return;
if (*string == '=')
{
char *end; /* Not uschar */
memset(selector, 0, sizeof(*selector)*selsize);
*selector = strtoul(CS string+1, &end, 0);
- if (*end == 0) return;
+ if (!*end) return;
errmsg = string_sprintf("malformed numeric %s_selector setting: %s", which,
string);
goto ERROR_RETURN;
int len;
bit_table *start, *end;
- while (isspace(*string)) string++;
- if (*string == 0) return;
+ Uskip_whitespace(&string);
+ if (!*string) return;
if (*string != '+' && *string != '-')
{
bit_table *middle = start + (end - start)/2;
int c = Ustrncmp(s, middle->name, len);
if (c == 0)
- {
if (middle->name[len] != 0) c = -1; else
{
unsigned int bit = middle->bit;
break; /* Out of loop to match selector name */
}
- }
if (c < 0) end = middle; else start = middle + 1;
} /* Loop to match selector name */
The first use of this is in ACL logic, "control = debug/tag=foo/opts=+expand"
which can be combined with conditions, etc, to activate extra logging only
-for certain sources. The second use is inetd wait mode debug preservation. */
+for certain sources. The second use is inetd wait mode debug preservation.
+
+It might be nice, in ACL-initiated pretrigger mode, to not create the file
+immediately but only upon a trigger - but we'd need another cmdline option
+to pass the name through child_exxec_exim(). */
void
debug_logging_activate(uschar *tag_name, uschar *opts)
{
-int fd = -1;
-
if (debug_file)
{
debug_printf("DEBUGGING ACTIVATED FROM WITHIN CONFIG.\n"
return;
}
-if (tag_name != NULL && (Ustrchr(tag_name, '/') != NULL))
+if (tag_name && (Ustrchr(tag_name, '/') != NULL))
{
log_write(0, LOG_MAIN|LOG_PANIC, "debug tag may not contain a '/' in: %s",
tag_name);
if (!*file_path) set_file_path();
-open_log(&fd, lt_debug, tag_name);
+open_log(&debug_fd, lt_debug, tag_name);
-if (fd != -1)
- debug_file = fdopen(fd, "w");
+if (debug_fd != -1)
+ debug_file = fdopen(debug_fd, "w");
else
log_write(0, LOG_MAIN|LOG_PANIC, "unable to open debug log");
}
void
-debug_logging_stop(void)
+debug_logging_stop(BOOL kill)
{
+debug_pretrigger_discard();
if (!debug_file || !debuglog_name[0]) return;
debug_selector = 0;
fclose(debug_file);
debug_file = NULL;
-unlink_log(lt_debug);
+debug_fd = -1;
+if (kill) unlink_log(lt_debug);
}
git://git.exim.org / exim.git / blobdiff