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/*-------------------------------------------------------------------------
*
* be-secure-common.c
*
* common implementation-independent SSL support code
*
* While be-secure.c contains the interfaces that the rest of the
* communications code calls, this file contains support routines that are
* used by the library-specific implementations such as be-secure-openssl.c.
*
* Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* src/backend/libpq/be-secure-common.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <sys/stat.h>
#include <unistd.h>
#include "common/percentrepl.h"
#include "common/string.h"
#include "libpq/libpq.h"
#include "storage/fd.h"
/*
* Run ssl_passphrase_command
*
* prompt will be substituted for %p. is_server_start determines the loglevel
* of error messages.
*
* The result will be put in buffer buf, which is of size size. The return
* value is the length of the actual result.
*/
int
run_ssl_passphrase_command(const char *prompt, bool is_server_start, char *buf, int size)
{
int loglevel = is_server_start ? ERROR : LOG;
char *command;
FILE *fh;
int pclose_rc;
size_t len = 0;
Assert(prompt);
Assert(size > 0);
buf[0] = '\0';
command = replace_percent_placeholders(ssl_passphrase_command, "ssl_passphrase_command", "p", prompt);
fh = OpenPipeStream(command, "r");
if (fh == NULL)
{
ereport(loglevel,
(errcode_for_file_access(),
errmsg("could not execute command \"%s\": %m",
command)));
goto error;
}
if (!fgets(buf, size, fh))
{
if (ferror(fh))
{
explicit_bzero(buf, size);
ereport(loglevel,
(errcode_for_file_access(),
errmsg("could not read from command \"%s\": %m",
command)));
goto error;
}
}
pclose_rc = ClosePipeStream(fh);
if (pclose_rc == -1)
{
explicit_bzero(buf, size);
ereport(loglevel,
(errcode_for_file_access(),
errmsg("could not close pipe to external command: %m")));
goto error;
}
else if (pclose_rc != 0)
{
explicit_bzero(buf, size);
ereport(loglevel,
(errcode_for_file_access(),
errmsg("command \"%s\" failed",
command),
errdetail_internal("%s", wait_result_to_str(pclose_rc))));
goto error;
}
/* strip trailing newline and carriage return */
len = pg_strip_crlf(buf);
error:
pfree(command);
return len;
}
/*
* Check permissions for SSL key files.
*/
bool
check_ssl_key_file_permissions(const char *ssl_key_file, bool isServerStart)
{
int loglevel = isServerStart ? FATAL : LOG;
struct stat buf;
if (stat(ssl_key_file, &buf) != 0)
{
ereport(loglevel,
(errcode_for_file_access(),
errmsg("could not access private key file \"%s\": %m",
ssl_key_file)));
return false;
}
/* Key file must be a regular file */
if (!S_ISREG(buf.st_mode))
{
ereport(loglevel,
(errcode(ERRCODE_CONFIG_FILE_ERROR),
errmsg("private key file \"%s\" is not a regular file",
ssl_key_file)));
return false;
}
/*
* Refuse to load key files owned by users other than us or root, and
* require no public access to the key file. If the file is owned by us,
* require mode 0600 or less. If owned by root, require 0640 or less to
* allow read access through either our gid or a supplementary gid that
* allows us to read system-wide certificates.
*
* Note that roughly similar checks are performed in
* src/interfaces/libpq/fe-secure-openssl.c so any changes here may need
* to be made there as well. The environment is different though; this
* code can assume that we're not running as root.
*
* Ideally we would do similar permissions checks on Windows, but it is
* not clear how that would work since Unix-style permissions may not be
* available.
*/
#if !defined(WIN32) && !defined(__CYGWIN__)
if (buf.st_uid != geteuid() && buf.st_uid != 0)
{
ereport(loglevel,
(errcode(ERRCODE_CONFIG_FILE_ERROR),
errmsg("private key file \"%s\" must be owned by the database user or root",
ssl_key_file)));
return false;
}
if ((buf.st_uid == geteuid() && buf.st_mode & (S_IRWXG | S_IRWXO)) ||
(buf.st_uid == 0 && buf.st_mode & (S_IWGRP | S_IXGRP | S_IRWXO)))
{
ereport(loglevel,
(errcode(ERRCODE_CONFIG_FILE_ERROR),
errmsg("private key file \"%s\" has group or world access",
ssl_key_file),
errdetail("File must have permissions u=rw (0600) or less if owned by the database user, or permissions u=rw,g=r (0640) or less if owned by root.")));
return false;
}
#endif
return true;
}
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