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![Trond Myklebust](/assets/img/avatar_default.png)
Fix a regression reported by Max Kellermann whereby kernel profiling showed that his clients were spending 45% of their time in rpcauth_lookup_credcache. It turns out that although his processes had identical uid/gid/groups, generic_match() was failing to detect this, because the task->group_info pointers were not shared. This again lead to the creation of a huge number of identical credentials at the RPC layer. The regression is fixed by comparing the contents of task->group_info if the actual pointers are not identical. Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
193 lines
4.7 KiB
C
193 lines
4.7 KiB
C
/*
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* Generic RPC credential
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*
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* Copyright (C) 2008, Trond Myklebust <Trond.Myklebust@netapp.com>
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*/
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#include <linux/err.h>
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#include <linux/types.h>
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#include <linux/module.h>
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#include <linux/sched.h>
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#include <linux/sunrpc/auth.h>
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#include <linux/sunrpc/clnt.h>
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#include <linux/sunrpc/debug.h>
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#include <linux/sunrpc/sched.h>
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#ifdef RPC_DEBUG
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# define RPCDBG_FACILITY RPCDBG_AUTH
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#endif
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#define RPC_MACHINE_CRED_USERID ((uid_t)0)
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#define RPC_MACHINE_CRED_GROUPID ((gid_t)0)
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struct generic_cred {
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struct rpc_cred gc_base;
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struct auth_cred acred;
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};
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static struct rpc_auth generic_auth;
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static struct rpc_cred_cache generic_cred_cache;
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static const struct rpc_credops generic_credops;
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/*
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* Public call interface
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*/
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struct rpc_cred *rpc_lookup_cred(void)
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{
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return rpcauth_lookupcred(&generic_auth, 0);
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}
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EXPORT_SYMBOL_GPL(rpc_lookup_cred);
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/*
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* Public call interface for looking up machine creds.
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*/
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struct rpc_cred *rpc_lookup_machine_cred(void)
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{
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struct auth_cred acred = {
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.uid = RPC_MACHINE_CRED_USERID,
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.gid = RPC_MACHINE_CRED_GROUPID,
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.machine_cred = 1,
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};
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dprintk("RPC: looking up machine cred\n");
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return generic_auth.au_ops->lookup_cred(&generic_auth, &acred, 0);
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}
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EXPORT_SYMBOL_GPL(rpc_lookup_machine_cred);
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static void
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generic_bind_cred(struct rpc_task *task, struct rpc_cred *cred)
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{
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struct rpc_auth *auth = task->tk_client->cl_auth;
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struct auth_cred *acred = &container_of(cred, struct generic_cred, gc_base)->acred;
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struct rpc_cred *ret;
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ret = auth->au_ops->lookup_cred(auth, acred, 0);
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if (!IS_ERR(ret))
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task->tk_msg.rpc_cred = ret;
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else
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task->tk_status = PTR_ERR(ret);
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}
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/*
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* Lookup generic creds for current process
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*/
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static struct rpc_cred *
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generic_lookup_cred(struct rpc_auth *auth, struct auth_cred *acred, int flags)
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{
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return rpcauth_lookup_credcache(&generic_auth, acred, flags);
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}
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static struct rpc_cred *
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generic_create_cred(struct rpc_auth *auth, struct auth_cred *acred, int flags)
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{
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struct generic_cred *gcred;
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gcred = kmalloc(sizeof(*gcred), GFP_KERNEL);
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if (gcred == NULL)
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return ERR_PTR(-ENOMEM);
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rpcauth_init_cred(&gcred->gc_base, acred, &generic_auth, &generic_credops);
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gcred->gc_base.cr_flags = 1UL << RPCAUTH_CRED_UPTODATE;
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gcred->acred.uid = acred->uid;
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gcred->acred.gid = acred->gid;
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gcred->acred.group_info = acred->group_info;
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if (gcred->acred.group_info != NULL)
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get_group_info(gcred->acred.group_info);
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gcred->acred.machine_cred = acred->machine_cred;
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dprintk("RPC: allocated %s cred %p for uid %d gid %d\n",
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gcred->acred.machine_cred ? "machine" : "generic",
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gcred, acred->uid, acred->gid);
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return &gcred->gc_base;
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}
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static void
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generic_free_cred(struct rpc_cred *cred)
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{
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struct generic_cred *gcred = container_of(cred, struct generic_cred, gc_base);
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dprintk("RPC: generic_free_cred %p\n", gcred);
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if (gcred->acred.group_info != NULL)
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put_group_info(gcred->acred.group_info);
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kfree(gcred);
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}
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static void
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generic_free_cred_callback(struct rcu_head *head)
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{
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struct rpc_cred *cred = container_of(head, struct rpc_cred, cr_rcu);
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generic_free_cred(cred);
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}
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static void
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generic_destroy_cred(struct rpc_cred *cred)
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{
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call_rcu(&cred->cr_rcu, generic_free_cred_callback);
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}
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/*
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* Match credentials against current process creds.
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*/
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static int
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generic_match(struct auth_cred *acred, struct rpc_cred *cred, int flags)
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{
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struct generic_cred *gcred = container_of(cred, struct generic_cred, gc_base);
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int i;
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if (gcred->acred.uid != acred->uid ||
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gcred->acred.gid != acred->gid ||
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gcred->acred.machine_cred != acred->machine_cred)
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goto out_nomatch;
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/* Optimisation in the case where pointers are identical... */
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if (gcred->acred.group_info == acred->group_info)
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goto out_match;
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/* Slow path... */
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if (gcred->acred.group_info->ngroups != acred->group_info->ngroups)
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goto out_nomatch;
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for (i = 0; i < gcred->acred.group_info->ngroups; i++) {
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if (GROUP_AT(gcred->acred.group_info, i) !=
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GROUP_AT(acred->group_info, i))
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goto out_nomatch;
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}
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out_match:
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return 1;
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out_nomatch:
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return 0;
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}
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void __init rpc_init_generic_auth(void)
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{
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spin_lock_init(&generic_cred_cache.lock);
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}
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void __exit rpc_destroy_generic_auth(void)
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{
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rpcauth_clear_credcache(&generic_cred_cache);
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}
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static struct rpc_cred_cache generic_cred_cache = {
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{{ NULL, },},
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};
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static const struct rpc_authops generic_auth_ops = {
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.owner = THIS_MODULE,
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.au_name = "Generic",
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.lookup_cred = generic_lookup_cred,
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.crcreate = generic_create_cred,
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};
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static struct rpc_auth generic_auth = {
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.au_ops = &generic_auth_ops,
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.au_count = ATOMIC_INIT(0),
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.au_credcache = &generic_cred_cache,
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};
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static const struct rpc_credops generic_credops = {
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.cr_name = "Generic cred",
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.crdestroy = generic_destroy_cred,
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.crbind = generic_bind_cred,
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.crmatch = generic_match,
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};
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