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fix: REVOKE-vs-GRANT bug + escape ' in CREATE LOGIN passwords #38

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Merged
robert-chiniquy merged 3 commits into from
May 20, 2026
Merged

fix: REVOKE-vs-GRANT bug + escape ' in CREATE LOGIN passwords #38

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b4337e2
fix: RevokePermissionOnDatabase issues REVOKE, not GRANT
robert-chiniquy May 20, 2026
c64c590
fix: escape ' in passwords passed to CREATE LOGIN
robert-chiniquy May 20, 2026
2cf2612
fix: address bot suggestions on #38
robert-chiniquy May 20, 2026
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6 changes: 3 additions & 3 deletions pkg/mssqldb/databases.go
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Original file line number Diff line number Diff line change
Expand Up @@ -117,7 +117,7 @@ func (c *Client) GrantPermissionOnDatabase(ctx context.Context, permission, db,

l.Debug("SQL QUERY", zap.String("q", command))

_, err := c.db.ExecContext(ctx, command, permission, db, user)
_, err := c.db.ExecContext(ctx, command)
if err != nil {
return err
}
Expand All @@ -144,13 +144,13 @@ func (c *Client) RevokePermissionOnDatabase(ctx context.Context, permission, db,
}

command := fmt.Sprintf(
"GRANT %s ON DATABASE::[%s] TO [%s];",
"REVOKE %s ON DATABASE::[%s] FROM [%s];",
fullPermission,
db,
user,
)

_, err := c.db.ExecContext(ctx, command, fullPermission, db, user)
_, err := c.db.ExecContext(ctx, command)
if err != nil {
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@github-actions github-actions Bot May 20, 2026

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🟡 Suggestion: The sibling GrantPermissionOnDatabase (line ~126) still passes inert positional args permission, db, user to ExecContext — the same pattern cleaned up here. Consider removing them there too for consistency.

Suggested change
if err != nil {
_, err := c.db.ExecContext(ctx, command)

return err
}
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15 changes: 14 additions & 1 deletion pkg/mssqldb/users.go
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Original file line number Diff line number Diff line change
Expand Up @@ -386,6 +386,14 @@ const (
func (c *Client) CreateLogin(ctx context.Context, loginType LoginType, username, password string) error {
l := ctxzap.Extract(ctx)

// Username is interpolated into bracket-quoted SQL Server identifiers
// below. Reject characters that would let the value break out of the
// brackets (this is the same guard the rest of this package uses on
// identifier-interpolated inputs).
if strings.ContainsAny(username, "[]\"';") {
return fmt.Errorf("invalid characters in username")
}

var query string
switch loginType {
case LoginTypeWindows:
Expand All @@ -399,7 +407,12 @@ func (c *Client) CreateLogin(ctx context.Context, loginType LoginType, username,
// For SQL Server authentication, only username and password are used
loginName := fmt.Sprintf("[%s]", username)
l.Debug("creating SQL login", zap.String("login", loginName))
query = fmt.Sprintf("CREATE LOGIN %s WITH PASSWORD = '%s';", loginName, password)
// SQL Server string literals escape ' by doubling it. Without this,
// a password containing ' breaks out of the literal -- a SQL
// injection vector and at minimum a syntax error for legitimate
// users whose passwords contain '.
escapedPassword := strings.ReplaceAll(password, "'", "''")
query = fmt.Sprintf("CREATE LOGIN %s WITH PASSWORD = '%s';", loginName, escapedPassword)
Comment on lines 408 to +415
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@github-actions github-actions Bot May 20, 2026

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🟡 Suggestion: The password escaping is correct, but username is bracket-quoted via [%s] without escaping ] — a username containing ] can break out of the identifier quoting. Other functions in this file (lines 287, 334) validate inputs against []"'; before interpolation. Consider adding the same ContainsAny guard on username here, or escaping ] → ]] inside the brackets (SQL Server's bracket-identifier escape).

case LoginTypeAzureAD, LoginTypeEntraID:
// Azure AD and Entra ID use external provider
loginName := fmt.Sprintf("[%s]", username)
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