Fix inconsistent quoting of role names in ACLs.

getid() and putid(), which parse and deparse role names within ACL
input/output, applied isalnum() to see if a character within a role
name requires quoting.  They did this even for non-ASCII characters,
which is problematic because the results would depend on encoding,
locale, and perhaps even platform.  So it's possible that putid()
could elect not to quote some string that, later in some other
environment, getid() will decide is not a valid identifier, causing
dump/reload or similar failures.

To fix this in a way that won't risk interoperability problems
with unpatched versions, make getid() treat any non-ASCII as a
legitimate identifier character (hence not requiring quotes),
while making putid() treat any non-ASCII as requiring quoting.
We could remove the resulting excess quoting once we feel that
no unpatched servers remain in the wild, but that'll be years.

A lesser problem is that getid() did the wrong thing with an input
consisting of just two double quotes ("").  That has to represent an
empty string, but getid() read it as a single double quote instead.
The case cannot arise in the normal course of events, since we don't
allow empty-string role names.  But let's fix it while we're here.

Although we've not heard field reports of problems with non-ASCII
role names, there's clearly a hazard there, so back-patch to all
supported versions.

Reported-by: Peter Eisentraut <peter@eisentraut.org>
Author: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/3792884.1751492172@sss.pgh.pa.us
Backpatch-through: 13

diff --git a/src/backend/utils/adt/acl.c b/src/backend/utils/adt/acl.c
index ca3c5ee3df3ae2583b7230eb35af87c39aa5e3ca..1213f9106d5155120575e9df25724ef46ace5f74 100644 (file)
--- a/src/backend/utils/adt/acl.c
+++ b/src/backend/utils/adt/acl.c
@@ -134,6 +134,22 @@ static AclResult pg_role_aclcheck(Oid role_oid, Oid roleid, AclMode mode);
 static void RoleMembershipCacheCallback(Datum arg, int cacheid, uint32 hashvalue);
 
 
+/*
+ * Test whether an identifier char can be left unquoted in ACLs.
+ *
+ * Formerly, we used isalnum() even on non-ASCII characters, resulting in
+ * unportable behavior.  To ensure dump compatibility with old versions,
+ * we now treat high-bit-set characters as always requiring quoting during
+ * putid(), but getid() will always accept them without quotes.
+ */
+static inline bool
+is_safe_acl_char(unsigned char c, bool is_getid)
+{
+       if (IS_HIGHBIT_SET(c))
+               return is_getid;
+       return isalnum(c) || c == '_';
+}
+
 /*
  * getid
  *             Consumes the first alphanumeric string (identifier) found in string
@@ -159,21 +175,22 @@ getid(const char *s, char *n, Node *escontext)
 
        while (isspace((unsigned char) *s))
                s++;
-       /* This code had better match what putid() does, below */
        for (;
                 *s != '\0' &&
-                (isalnum((unsigned char) *s) ||
-                 *s == '_' ||
-                 *s == '"' ||
-                 in_quotes);
+                (in_quotes || *s == '"' || is_safe_acl_char(*s, true));
                 s++)
        {
                if (*s == '"')
                {
+                       if (!in_quotes)
+                       {
+                               in_quotes = true;
+                               continue;
+                       }
                        /* safe to look at next char (could be '\0' though) */
                        if (*(s + 1) != '"')
                        {
-                               in_quotes = !in_quotes;
+                               in_quotes = false;
                                continue;
                        }
                        /* it's an escaped double quote; skip the escaping char */
@@ -207,10 +224,10 @@ putid(char *p, const char *s)
        const char *src;
        bool            safe = true;
 
+       /* Detect whether we need to use double quotes */
        for (src = s; *src; src++)
        {
-               /* This test had better match what getid() does, above */
-               if (!isalnum((unsigned char) *src) && *src != '_')
+               if (!is_safe_acl_char(*src, false))
                {
                        safe = false;
                        break;

diff --git a/src/test/regress/expected/privileges.out b/src/test/regress/expected/privileges.out
index c25062c288f32351b94db98f5066880d817b9c46..85ece4c35d5233488b1100faef2bdc73b825c4f2 100644 (file)
--- a/src/test/regress/expected/privileges.out
+++ b/src/test/regress/expected/privileges.out
@@ -2568,6 +2568,26 @@ SELECT makeaclitem('regress_priv_user1'::regrole, 'regress_priv_user2'::regrole,
 SELECT makeaclitem('regress_priv_user1'::regrole, 'regress_priv_user2'::regrole,
        'SELECT, fake_privilege', FALSE);  -- error
 ERROR:  unrecognized privilege type: "fake_privilege"
+-- Test quoting and dequoting of user names in ACLs
+CREATE ROLE "regress_""quoted";
+SELECT makeaclitem('regress_"quoted'::regrole, 'regress_"quoted'::regrole,
+                   'SELECT', TRUE);
+               makeaclitem                
+------------------------------------------
+ "regress_""quoted"=r*/"regress_""quoted"
+(1 row)
+
+SELECT '"regress_""quoted"=r*/"regress_""quoted"'::aclitem;
+                 aclitem                  
+------------------------------------------
+ "regress_""quoted"=r*/"regress_""quoted"
+(1 row)
+
+SELECT '""=r*/""'::aclitem;  -- used to be misparsed as """"
+ERROR:  a name must follow the "/" sign
+LINE 1: SELECT '""=r*/""'::aclitem;
+               ^
+DROP ROLE "regress_""quoted";
 -- Test non-throwing aclitem I/O
 SELECT pg_input_is_valid('regress_priv_user1=r/regress_priv_user2', 'aclitem');
  pg_input_is_valid 

diff --git a/src/test/regress/sql/privileges.sql b/src/test/regress/sql/privileges.sql
index f337aa67c13f23204d3d97f59f16a7c331bcd6a7..8e8b79e343e802cd099440f311f34124cbf4dedc 100644 (file)
--- a/src/test/regress/sql/privileges.sql
+++ b/src/test/regress/sql/privileges.sql
@@ -1544,6 +1544,14 @@ SELECT makeaclitem('regress_priv_user1'::regrole, 'regress_priv_user2'::regrole,
 SELECT makeaclitem('regress_priv_user1'::regrole, 'regress_priv_user2'::regrole,
        'SELECT, fake_privilege', FALSE);  -- error
 
+-- Test quoting and dequoting of user names in ACLs
+CREATE ROLE "regress_""quoted";
+SELECT makeaclitem('regress_"quoted'::regrole, 'regress_"quoted'::regrole,
+                   'SELECT', TRUE);
+SELECT '"regress_""quoted"=r*/"regress_""quoted"'::aclitem;
+SELECT '""=r*/""'::aclitem;  -- used to be misparsed as """"
+DROP ROLE "regress_""quoted";
+
 -- Test non-throwing aclitem I/O
 SELECT pg_input_is_valid('regress_priv_user1=r/regress_priv_user2', 'aclitem');
 SELECT pg_input_is_valid('regress_priv_user1=r/', 'aclitem');