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Obstruct shell, SQL, and conninfo injection via database and role names.

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Due to simplistic quoting and confusion of database names with conninfo
strings, roles with the CREATEDB or CREATEROLE option could escalate to
superuser privileges when a superuser next ran certain maintenance
commands.  The new coding rule for PQconnectdbParams() calls, documented
at conninfo_array_parse(), is to pass expand_dbname=true and wrap
literal database names in a trivial connection string.  Escape
zero-length values in appendConnStrVal().  Back-patch to 9.1 (all
supported versions).

Nathan Bossart, Michael Paquier, and Noah Misch.  Reviewed by Peter
Eisentraut.  Reported by Nathan Bossart.

Security: CVE-2016-5424
This commit is contained in:
Noah Misch
2016-08-08 10:07:46 -04:00
parent 41f18f021a
commit fcd15f1358
20 changed files with 315 additions and 67 deletions
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67
src/fe_utils/string_utils.c
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@ -488,10 +488,10 @@ appendConnStrVal(PQExpBuffer buf, const char *str)
bool needquotes;
/*
* If the string consists entirely of plain ASCII characters, no need to
* quote it. This is quite conservative, but better safe than sorry.
* If the string is one or more plain ASCII characters, no need to quote
* it. This is quite conservative, but better safe than sorry.
*/
needquotes = false;
needquotes = true;
for (s = str; *s; s++)
{
if (!((*s >= 'a' && *s <= 'z') || (*s >= 'A' && *s <= 'Z') ||
@ -500,6 +500,7 @@ appendConnStrVal(PQExpBuffer buf, const char *str)
needquotes = true;
break;
}
needquotes = false;
}
if (needquotes)
@ -521,6 +522,66 @@ appendConnStrVal(PQExpBuffer buf, const char *str)
}
/*
* Append a psql meta-command that connects to the given database with the
* then-current connection's user, host and port.
*/
void
appendPsqlMetaConnect(PQExpBuffer buf, const char *dbname)
{
const char *s;
bool complex;
/*
* If the name is plain ASCII characters, emit a trivial "\connect "foo"".
* For other names, even many not technically requiring it, skip to the
* general case. No database has a zero-length name.
*/
complex = false;
for (s = dbname; *s; s++)
{
if (*s == '\n' || *s == '\r')
{
fprintf(stderr,
_("database name contains a newline or carriage return: \"%s\"\n"),
dbname);
exit(EXIT_FAILURE);
}
if (!((*s >= 'a' && *s <= 'z') || (*s >= 'A' && *s <= 'Z') ||
(*s >= '0' && *s <= '9') || *s == '_' || *s == '.'))
{
complex = true;
}
}
appendPQExpBufferStr(buf, "\\connect ");
if (complex)
{
PQExpBufferData connstr;
initPQExpBuffer(&connstr);
appendPQExpBuffer(&connstr, "dbname=");
appendConnStrVal(&connstr, dbname);
appendPQExpBuffer(buf, "-reuse-previous=on ");
/*
* As long as the name does not contain a newline, SQL identifier
* quoting satisfies the psql meta-command parser. Prefer not to
* involve psql-interpreted single quotes, which behaved differently
* before PostgreSQL 9.2.
*/
appendPQExpBufferStr(buf, fmtId(connstr.data));
termPQExpBuffer(&connstr);
}
else
appendPQExpBufferStr(buf, fmtId(dbname));
appendPQExpBufferChar(buf, '\n');
}
/*
* Deconstruct the text representation of a 1-dimensional Postgres array
* into individual items.