On Tue, Mar 31, 2015 at 1:12 PM, J. Bruce Fields <bfields@xxxxxxxxxxxx> wrote:
> Trond, this is kind of your baliwick, but do you mind if I take it
> instead? It's kind of a pain for my testing currently.
That's fine with me. I don't foresee any other changes to that code
for this next merge window, so no conflicts are expected.
> --b.
>
> On Tue, Mar 31, 2015 at 12:03:28PM -0400, Jeff Layton wrote:
>> v2: gracefully handle the case where some dentry pointers end up NULL
>> and be more dilligent about zeroing out dentry pointers
>>
>> We currently have a problem that SELinux policy is being enforced when
>> creating debugfs files. If a debugfs file is created as a side effect of
>> doing some syscall, then that creation can fail if the SELinux policy
>> for that process prevents it.
>>
>> This seems wrong. We don't do that for files under /proc, for instance,
>> so Bruce has proposed a patch to fix that.
>>
>> While discussing that patch however, Greg K.H. stated:
>>
>> "No kernel code should care / fail if a debugfs function fails, so
>> please fix up the sunrpc code first."
>>
>> This patch converts all of the sunrpc debugfs setup code to be void
>> return functins, and the callers to not look for errors from those
>> functions.
>>
>> This should allow rpc_clnt and rpc_xprt creation to work, even if the
>> kernel fails to create debugfs files for some reason.
>>
>> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
>> Acked-by: "J. Bruce Fields" <bfields@xxxxxxxxxxxx>
>> Signed-off-by: Jeff Layton <jeff.layton@xxxxxxxxxxxxxxx>
>> ---
>> include/linux/sunrpc/debug.h | 18 +++++++--------
>> net/sunrpc/clnt.c | 4 +---
>> net/sunrpc/debugfs.c | 52 ++++++++++++++++++++++++--------------------
>> net/sunrpc/sunrpc_syms.c | 7 +-----
>> net/sunrpc/xprt.c | 7 +-----
>> 5 files changed, 41 insertions(+), 47 deletions(-)
>>
>> diff --git a/include/linux/sunrpc/debug.h b/include/linux/sunrpc/debug.h
>> index c57d8ea0716c..59a7889e15db 100644
>> --- a/include/linux/sunrpc/debug.h
>> +++ b/include/linux/sunrpc/debug.h
>> @@ -60,17 +60,17 @@ struct rpc_xprt;
>> #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
>> void rpc_register_sysctl(void);
>> void rpc_unregister_sysctl(void);
>> -int sunrpc_debugfs_init(void);
>> +void sunrpc_debugfs_init(void);
>> void sunrpc_debugfs_exit(void);
>> -int rpc_clnt_debugfs_register(struct rpc_clnt *);
>> +void rpc_clnt_debugfs_register(struct rpc_clnt *);
>> void rpc_clnt_debugfs_unregister(struct rpc_clnt *);
>> -int rpc_xprt_debugfs_register(struct rpc_xprt *);
>> +void rpc_xprt_debugfs_register(struct rpc_xprt *);
>> void rpc_xprt_debugfs_unregister(struct rpc_xprt *);
>> #else
>> -static inline int
>> +static inline void
>> sunrpc_debugfs_init(void)
>> {
>> - return 0;
>> + return;
>> }
>>
>> static inline void
>> @@ -79,10 +79,10 @@ sunrpc_debugfs_exit(void)
>> return;
>> }
>>
>> -static inline int
>> +static inline void
>> rpc_clnt_debugfs_register(struct rpc_clnt *clnt)
>> {
>> - return 0;
>> + return;
>> }
>>
>> static inline void
>> @@ -91,10 +91,10 @@ rpc_clnt_debugfs_unregister(struct rpc_clnt *clnt)
>> return;
>> }
>>
>> -static inline int
>> +static inline void
>> rpc_xprt_debugfs_register(struct rpc_xprt *xprt)
>> {
>> - return 0;
>> + return;
>> }
>>
>> static inline void
>> diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
>> index 612aa73bbc60..e6ce1517367f 100644
>> --- a/net/sunrpc/clnt.c
>> +++ b/net/sunrpc/clnt.c
>> @@ -303,9 +303,7 @@ static int rpc_client_register(struct rpc_clnt *clnt,
>> struct super_block *pipefs_sb;
>> int err;
>>
>> - err = rpc_clnt_debugfs_register(clnt);
>> - if (err)
>> - return err;
>> + rpc_clnt_debugfs_register(clnt);
>>
>> pipefs_sb = rpc_get_sb_net(net);
>> if (pipefs_sb) {
>> diff --git a/net/sunrpc/debugfs.c b/net/sunrpc/debugfs.c
>> index e811f390f9f6..82962f7e6e88 100644
>> --- a/net/sunrpc/debugfs.c
>> +++ b/net/sunrpc/debugfs.c
>> @@ -129,48 +129,52 @@ static const struct file_operations tasks_fops = {
>> .release = tasks_release,
>> };
>>
>> -int
>> +void
>> rpc_clnt_debugfs_register(struct rpc_clnt *clnt)
>> {
>> - int len, err;
>> + int len;
>> char name[24]; /* enough for "../../rpc_xprt/ + 8 hex digits + NULL */
>> + struct rpc_xprt *xprt;
>>
>> /* Already registered? */
>> - if (clnt->cl_debugfs)
>> - return 0;
>> + if (clnt->cl_debugfs || !rpc_clnt_dir)
>> + return;
>>
>> len = snprintf(name, sizeof(name), "%x", clnt->cl_clid);
>> if (len >= sizeof(name))
>> - return -EINVAL;
>> + return;
>>
>> /* make the per-client dir */
>> clnt->cl_debugfs = debugfs_create_dir(name, rpc_clnt_dir);
>> if (!clnt->cl_debugfs)
>> - return -ENOMEM;
>> + return;
>>
>> /* make tasks file */
>> - err = -ENOMEM;
>> if (!debugfs_create_file("tasks", S_IFREG | S_IRUSR, clnt->cl_debugfs,
>> clnt, &tasks_fops))
>> goto out_err;
>>
>> - err = -EINVAL;
>> rcu_read_lock();
>> + xprt = rcu_dereference(clnt->cl_xprt);
>> + /* no "debugfs" dentry? Don't bother with the symlink. */
>> + if (!xprt->debugfs) {
>> + rcu_read_unlock();
>> + return;
>> + }
>> len = snprintf(name, sizeof(name), "../../rpc_xprt/%s",
>> - rcu_dereference(clnt->cl_xprt)->debugfs->d_name.name);
>> + xprt->debugfs->d_name.name);
>> rcu_read_unlock();
>> +
>> if (len >= sizeof(name))
>> goto out_err;
>>
>> - err = -ENOMEM;
>> if (!debugfs_create_symlink("xprt", clnt->cl_debugfs, name))
>> goto out_err;
>>
>> - return 0;
>> + return;
>> out_err:
>> debugfs_remove_recursive(clnt->cl_debugfs);
>> clnt->cl_debugfs = NULL;
>> - return err;
>> }
>>
>> void
>> @@ -226,33 +230,33 @@ static const struct file_operations xprt_info_fops = {
>> .release = xprt_info_release,
>> };
>>
>> -int
>> +void
>> rpc_xprt_debugfs_register(struct rpc_xprt *xprt)
>> {
>> int len, id;
>> static atomic_t cur_id;
>> char name[9]; /* 8 hex digits + NULL term */
>>
>> + if (!rpc_xprt_dir)
>> + return;
>> +
>> id = (unsigned int)atomic_inc_return(&cur_id);
>>
>> len = snprintf(name, sizeof(name), "%x", id);
>> if (len >= sizeof(name))
>> - return -EINVAL;
>> + return;
>>
>> /* make the per-client dir */
>> xprt->debugfs = debugfs_create_dir(name, rpc_xprt_dir);
>> if (!xprt->debugfs)
>> - return -ENOMEM;
>> + return;
>>
>> /* make tasks file */
>> if (!debugfs_create_file("info", S_IFREG | S_IRUSR, xprt->debugfs,
>> xprt, &xprt_info_fops)) {
>> debugfs_remove_recursive(xprt->debugfs);
>> xprt->debugfs = NULL;
>> - return -ENOMEM;
>> }
>> -
>> - return 0;
>> }
>>
>> void
>> @@ -266,14 +270,17 @@ void __exit
>> sunrpc_debugfs_exit(void)
>> {
>> debugfs_remove_recursive(topdir);
>> + topdir = NULL;
>> + rpc_clnt_dir = NULL;
>> + rpc_xprt_dir = NULL;
>> }
>>
>> -int __init
>> +void __init
>> sunrpc_debugfs_init(void)
>> {
>> topdir = debugfs_create_dir("sunrpc", NULL);
>> if (!topdir)
>> - goto out;
>> + return;
>>
>> rpc_clnt_dir = debugfs_create_dir("rpc_clnt", topdir);
>> if (!rpc_clnt_dir)
>> @@ -283,10 +290,9 @@ sunrpc_debugfs_init(void)
>> if (!rpc_xprt_dir)
>> goto out_remove;
>>
>> - return 0;
>> + return;
>> out_remove:
>> debugfs_remove_recursive(topdir);
>> topdir = NULL;
>> -out:
>> - return -ENOMEM;
>> + rpc_clnt_dir = NULL;
>> }
>> diff --git a/net/sunrpc/sunrpc_syms.c b/net/sunrpc/sunrpc_syms.c
>> index e37fbed87956..ee5d3d253102 100644
>> --- a/net/sunrpc/sunrpc_syms.c
>> +++ b/net/sunrpc/sunrpc_syms.c
>> @@ -98,10 +98,7 @@ init_sunrpc(void)
>> if (err)
>> goto out4;
>>
>> - err = sunrpc_debugfs_init();
>> - if (err)
>> - goto out5;
>> -
>> + sunrpc_debugfs_init();
>> #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
>> rpc_register_sysctl();
>> #endif
>> @@ -109,8 +106,6 @@ init_sunrpc(void)
>> init_socket_xprt(); /* clnt sock transport */
>> return 0;
>>
>> -out5:
>> - unregister_rpc_pipefs();
>> out4:
>> unregister_pernet_subsys(&sunrpc_net_ops);
>> out3:
>> diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
>> index e3015aede0d9..9949722d99ce 100644
>> --- a/net/sunrpc/xprt.c
>> +++ b/net/sunrpc/xprt.c
>> @@ -1331,7 +1331,6 @@ static void xprt_init(struct rpc_xprt *xprt, struct net *net)
>> */
>> struct rpc_xprt *xprt_create_transport(struct xprt_create *args)
>> {
>> - int err;
>> struct rpc_xprt *xprt;
>> struct xprt_class *t;
>>
>> @@ -1372,11 +1371,7 @@ found:
>> return ERR_PTR(-ENOMEM);
>> }
>>
>> - err = rpc_xprt_debugfs_register(xprt);
>> - if (err) {
>> - xprt_destroy(xprt);
>> - return ERR_PTR(err);
>> - }
>> + rpc_xprt_debugfs_register(xprt);
>>
>> dprintk("RPC: created transport %p with %u slots\n", xprt,
>> xprt->max_reqs);
>> --
>> 2.1.0
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