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Introduce a psql "\connect -reuse-previous=on|off" option. 

The decision to reuse values of parameters from a previous connection
has been based on whether the new target is a conninfo string.  Add this
means of overriding that default.  This feature arose as one component
of a fix for security vulnerabilities in pg_dump, pg_dumpall, and
pg_upgrade, so back-patch to 9.1 (all supported versions).  In 9.3 and
later, comment paragraphs that required update had already-incorrect
claims about behavior when no connection is open; fix those problems.

Security: CVE-2016-5424
This commit is contained in:
Noah Misch 2016-08-08 10:07:46 -04:00
parent db951dd195
commit 6655c07574
3 changed files with 90 additions and 46 deletions
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21
doc/src/sgml/ref/psql-ref.sgml
View File

@ -799,7 +799,7 @@ testdb=>
</varlistentry>
<varlistentry>
<term><literal>\c</literal> or <literal>\connect</literal> <literal>[ <replaceable class="parameter">dbname</replaceable> [ <replaceable class="parameter">username</replaceable> ] [ <replaceable class="parameter">host</replaceable> ] [ <replaceable class="parameter">port</replaceable> ] ] | <replaceable class="parameter">conninfo</replaceable> </literal></term>
<term><literal>\c</literal> or <literal>\connect [ -reuse-previous=<replaceable class="parameter">on|off</replaceable> ] [ <replaceable class="parameter">dbname</replaceable> [ <replaceable class="parameter">username</replaceable> ] [ <replaceable class="parameter">host</replaceable> ] [ <replaceable class="parameter">port</replaceable> ] | <replaceable class="parameter">conninfo</replaceable> ]</literal></term>
<listitem>
<para>
Establishes a new connection to a <productname>PostgreSQL</>
@ -809,16 +809,19 @@ testdb=&gt;
</para>
<para>
When using positional parameters, if any of
<replaceable class="parameter">dbname</replaceable>,
Where the command omits database name, user, host, or port, the new
connection can reuse values from the previous connection. By default,
values from the previous connection are reused except when processing
a <literal>conninfo</> string. Passing a first argument
of <literal>-reuse-previous=on</>
or <literal>-reuse-previous=off</literal> overrides that default.
When the command neither specifies nor reuses a particular parameter,
the <application>libpq</application> default is used. Specifying any
of <replaceable class="parameter">dbname</replaceable>,
<replaceable class="parameter">username</replaceable>,
<replaceable class="parameter">host</replaceable> or
<replaceable class="parameter">port</replaceable> are omitted or
specified as <literal>-</literal>, the value of that parameter from
the previous connection is used; if there is no previous connection,
the <application>libpq</application> default for the parameter's value
is used. When using <literal>conninfo</> strings, no values from the
previous connection are used for the new connection.
<replaceable class="parameter">port</replaceable>
as <literal>-</literal> is equivalent to omitting that parameter.
</para>
<para>

113
src/bin/psql/command.c
View File

@ -56,7 +56,8 @@ static backslashResult exec_command(const char *cmd,
PQExpBuffer query_buf);
static bool do_edit(const char *filename_arg, PQExpBuffer query_buf,
int lineno, bool *edited);
static bool do_connect(char *dbname, char *user, char *host, char *port);
static bool do_connect(enum trivalue reuse_previous_specification,
char *dbname, char *user, char *host, char *port);
static bool do_shell(const char *command);
static bool do_watch(PQExpBuffer query_buf, long sleep);
static bool lookup_function_oid(const char *desc, Oid *foid);
@ -217,12 +218,9 @@ exec_command(const char *cmd,
/*
* \c or \connect -- connect to database using the specified parameters.
*
* \c dbname user host port
* \c [-reuse-previous=BOOL] dbname user host port
*
* If any of these parameters are omitted or specified as '-', the current
* value of the parameter will be used instead. If the parameter has no
* current value, the default value for that parameter will be used. Some
* examples:
* Specifying a parameter as '-' is equivalent to omitting it. Examples:
*
* \c - - hst Connect to current database on current port of host
* "hst" as current user. \c - usr - prt Connect to current database on
@ -231,17 +229,31 @@ exec_command(const char *cmd,
*/
else if (strcmp(cmd, "c") == 0 || strcmp(cmd, "connect") == 0)
{
static const char prefix[] = "-reuse-previous=";
char *opt1,
*opt2,
*opt3,
*opt4;
enum trivalue reuse_previous;
opt1 = read_connect_arg(scan_state);
if (opt1 != NULL && strncmp(opt1, prefix, sizeof(prefix) - 1) == 0)
{
reuse_previous =
ParseVariableBool(opt1 + sizeof(prefix) - 1, prefix) ?
TRI_YES : TRI_NO;
free(opt1);
opt1 = read_connect_arg(scan_state);
}
else
reuse_previous = TRI_DEFAULT;
opt2 = read_connect_arg(scan_state);
opt3 = read_connect_arg(scan_state);
opt4 = read_connect_arg(scan_state);
success = do_connect(opt1, opt2, opt3, opt4);
success = do_connect(reuse_previous, opt1, opt2, opt3, opt4);
free(opt1);
free(opt2);
@ -1599,22 +1611,25 @@ param_is_newly_set(const char *old_val, const char *new_val)
/*
* do_connect -- handler for \connect
*
* Connects to a database with given parameters. If there exists an
* established connection, NULL values will be replaced with the ones
* in the current connection. Otherwise NULL will be passed for that
* parameter to PQconnectdbParams(), so the libpq defaults will be used.
* Connects to a database with given parameters. Absent an established
* connection, all parameters are required. Given -reuse-previous=off or a
* connection string without -reuse-previous=on, NULL values will pass through
* to PQconnectdbParams(), so the libpq defaults will be used. Otherwise, NULL
* values will be replaced with the ones in the current connection.
*
* In interactive mode, if connection fails with the given parameters,
* the old connection will be kept.
*/
static bool
do_connect(char *dbname, char *user, char *host, char *port)
do_connect(enum trivalue reuse_previous_specification,
char *dbname, char *user, char *host, char *port)
{
PGconn *o_conn = pset.db,
*n_conn;
char *password = NULL;
bool keep_password;
bool has_connection_string;
bool reuse_previous;
if (!o_conn && (!dbname || !user || !host || !port))
{
@ -1628,16 +1643,35 @@ do_connect(char *dbname, char *user, char *host, char *port)
return false;
}
/* grab values from the old connection, unless supplied by caller */
if (!user)
user = PQuser(o_conn);
if (!host)
host = PQhost(o_conn);
if (!port)
port = PQport(o_conn);
has_connection_string = dbname ?
recognized_connection_string(dbname) : false;
switch (reuse_previous_specification)
{
case TRI_YES:
reuse_previous = true;
break;
case TRI_NO:
reuse_previous = false;
break;
default:
reuse_previous = !has_connection_string;
break;
}
/* Silently ignore arguments subsequent to a connection string. */
if (has_connection_string)
{
user = NULL;
host = NULL;
port = NULL;
}
has_connection_string =
dbname ? recognized_connection_string(dbname) : false;
/* grab missing values from the old connection */
if (!user && reuse_previous)
user = PQuser(o_conn);
if (!host && reuse_previous)
host = PQhost(o_conn);
if (!port && reuse_previous)
port = PQport(o_conn);
/*
* Any change in the parameters read above makes us discard the password.
@ -1655,10 +1689,10 @@ do_connect(char *dbname, char *user, char *host, char *port)
(port && PQport(o_conn) && strcmp(port, PQport(o_conn)) == 0);
/*
* Grab dbname from old connection unless supplied by caller. No password
* discard if this changes: passwords aren't (usually) database-specific.
* Grab missing dbname from old connection. No password discard if this
* changes: passwords aren't (usually) database-specific.
*/
if (!dbname)
if (!dbname && reuse_previous)
dbname = PQdb(o_conn);
/*
@ -1689,20 +1723,27 @@ do_connect(char *dbname, char *user, char *host, char *port)
#define PARAMS_ARRAY_SIZE 8
const char **keywords = pg_malloc(PARAMS_ARRAY_SIZE * sizeof(*keywords));
const char **values = pg_malloc(PARAMS_ARRAY_SIZE * sizeof(*values));
int paramnum = 0;
int paramnum = -1;
keywords[0] = "dbname";
values[0] = dbname;
keywords[++paramnum] = "host";
values[paramnum] = host;
keywords[++paramnum] = "port";
values[paramnum] = port;
keywords[++paramnum] = "user";
values[paramnum] = user;
if (!has_connection_string)
{
keywords[++paramnum] = "host";
values[paramnum] = host;
keywords[++paramnum] = "port";
values[paramnum] = port;
keywords[++paramnum] = "user";
values[paramnum] = user;
}
/*
* Position in the array matters when the dbname is a connection
* string, because settings in a connection string override earlier
* array entries only. Thus, user= in the connection string always
* takes effect, but client_encoding= often will not.
*
* If you change this code, also change the initial-connection code in
* main(). For no good reason, a connection string password= takes
* precedence in main() but not here.
*/
keywords[++paramnum] = "dbname";
values[paramnum] = dbname;
keywords[++paramnum] = "password";
values[paramnum] = password;
keywords[++paramnum] = "fallback_application_name";

2
src/bin/psql/startup.c
View File

@ -215,7 +215,7 @@ main(int argc, char *argv[])
values[2] = options.username;
keywords[3] = "password";
values[3] = password;
keywords[4] = "dbname";
keywords[4] = "dbname"; /* see do_connect() */
values[4] = (options.action == ACT_LIST_DB &&
options.dbname == NULL) ?
"postgres" : options.dbname;