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rtld: Account static TLS surplus for audit modules

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The new static TLS surplus size computation is

  surplus_tls = 192 * (nns-1) + 144 * nns + 512

where nns is controlled via the rtld.nns tunable. This commit
accounts audit modules too so nns = rtld.nns + audit modules.

rtld.nns should only include the namespaces required by the
application, namespaces for audit modules are accounted on top
of that so audit modules don't use up the static TLS that is
reserved for the application. This allows loading many audit
modules without tuning rtld.nns or using up static TLS, and it
fixes

FAIL: elf/tst-auditmany

Note that DL_NNS is currently a hard upper limit for nns, and
if rtld.nns + audit modules go over the limit that's a fatal
error. By default rtld.nns is 4 which allows 12 audit modules.

Counting the audit modules is based on existing audit string
parsing code, we cannot use GLRO(dl_naudit) before the modules
are actually loaded.
This commit is contained in:
Szabolcs Nagy
2020-07-07 10:49:11 +01:00
parent 0c7b002fac
commit 17796419b5
5 changed files with 51 additions and 13 deletions
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4
csu/libc-tls.c
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@@ -126,8 +126,8 @@ __libc_setup_tls (void)
break;
}
/* Calculate the size of the static TLS surplus. */
_dl_tls_static_surplus_init ();
/* Calculate the size of the static TLS surplus, with 0 auditors. */
_dl_tls_static_surplus_init (0);
/* We have to set up the TCB block which also (possibly) contains
'errno'. Therefore we avoid 'malloc' which might touch 'errno'.