sunrpc: make debugfs file creation failure non-fatal

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@linuxfoundation.org>
Acked-by: "J. Bruce Fields" <bfields@fieldses.org>
Signed-off-by: Jeff Layton <jeff.layton@primarydata.com>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
This commit is contained in:
Jeff Layton 2015-03-31 12:03:28 -04:00 committed by Trond Myklebust
parent 5d05e54af3
commit 3f94009816
5 changed files with 41 additions and 47 deletions

View File

@ -60,17 +60,17 @@ struct rpc_xprt;
#if IS_ENABLED(CONFIG_SUNRPC_DEBUG) #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
void rpc_register_sysctl(void); void rpc_register_sysctl(void);
void rpc_unregister_sysctl(void); void rpc_unregister_sysctl(void);
int sunrpc_debugfs_init(void); void sunrpc_debugfs_init(void);
void sunrpc_debugfs_exit(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 *); 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 *); void rpc_xprt_debugfs_unregister(struct rpc_xprt *);
#else #else
static inline int static inline void
sunrpc_debugfs_init(void) sunrpc_debugfs_init(void)
{ {
return 0; return;
} }
static inline void static inline void
@ -79,10 +79,10 @@ sunrpc_debugfs_exit(void)
return; return;
} }
static inline int static inline void
rpc_clnt_debugfs_register(struct rpc_clnt *clnt) rpc_clnt_debugfs_register(struct rpc_clnt *clnt)
{ {
return 0; return;
} }
static inline void static inline void
@ -91,10 +91,10 @@ rpc_clnt_debugfs_unregister(struct rpc_clnt *clnt)
return; return;
} }
static inline int static inline void
rpc_xprt_debugfs_register(struct rpc_xprt *xprt) rpc_xprt_debugfs_register(struct rpc_xprt *xprt)
{ {
return 0; return;
} }
static inline void static inline void

View File

@ -303,9 +303,7 @@ static int rpc_client_register(struct rpc_clnt *clnt,
struct super_block *pipefs_sb; struct super_block *pipefs_sb;
int err; int err;
err = rpc_clnt_debugfs_register(clnt); rpc_clnt_debugfs_register(clnt);
if (err)
return err;
pipefs_sb = rpc_get_sb_net(net); pipefs_sb = rpc_get_sb_net(net);
if (pipefs_sb) { if (pipefs_sb) {

View File

@ -129,48 +129,52 @@ static const struct file_operations tasks_fops = {
.release = tasks_release, .release = tasks_release,
}; };
int void
rpc_clnt_debugfs_register(struct rpc_clnt *clnt) rpc_clnt_debugfs_register(struct rpc_clnt *clnt)
{ {
int len, err; int len;
char name[24]; /* enough for "../../rpc_xprt/ + 8 hex digits + NULL */ char name[24]; /* enough for "../../rpc_xprt/ + 8 hex digits + NULL */
struct rpc_xprt *xprt;
/* Already registered? */ /* Already registered? */
if (clnt->cl_debugfs) if (clnt->cl_debugfs || !rpc_clnt_dir)
return 0; return;
len = snprintf(name, sizeof(name), "%x", clnt->cl_clid); len = snprintf(name, sizeof(name), "%x", clnt->cl_clid);
if (len >= sizeof(name)) if (len >= sizeof(name))
return -EINVAL; return;
/* make the per-client dir */ /* make the per-client dir */
clnt->cl_debugfs = debugfs_create_dir(name, rpc_clnt_dir); clnt->cl_debugfs = debugfs_create_dir(name, rpc_clnt_dir);
if (!clnt->cl_debugfs) if (!clnt->cl_debugfs)
return -ENOMEM; return;
/* make tasks file */ /* make tasks file */
err = -ENOMEM;
if (!debugfs_create_file("tasks", S_IFREG | S_IRUSR, clnt->cl_debugfs, if (!debugfs_create_file("tasks", S_IFREG | S_IRUSR, clnt->cl_debugfs,
clnt, &tasks_fops)) clnt, &tasks_fops))
goto out_err; goto out_err;
err = -EINVAL;
rcu_read_lock(); rcu_read_lock();
len = snprintf(name, sizeof(name), "../../rpc_xprt/%s", xprt = rcu_dereference(clnt->cl_xprt);
rcu_dereference(clnt->cl_xprt)->debugfs->d_name.name); /* no "debugfs" dentry? Don't bother with the symlink. */
if (!xprt->debugfs) {
rcu_read_unlock(); rcu_read_unlock();
return;
}
len = snprintf(name, sizeof(name), "../../rpc_xprt/%s",
xprt->debugfs->d_name.name);
rcu_read_unlock();
if (len >= sizeof(name)) if (len >= sizeof(name))
goto out_err; goto out_err;
err = -ENOMEM;
if (!debugfs_create_symlink("xprt", clnt->cl_debugfs, name)) if (!debugfs_create_symlink("xprt", clnt->cl_debugfs, name))
goto out_err; goto out_err;
return 0; return;
out_err: out_err:
debugfs_remove_recursive(clnt->cl_debugfs); debugfs_remove_recursive(clnt->cl_debugfs);
clnt->cl_debugfs = NULL; clnt->cl_debugfs = NULL;
return err;
} }
void void
@ -226,33 +230,33 @@ static const struct file_operations xprt_info_fops = {
.release = xprt_info_release, .release = xprt_info_release,
}; };
int void
rpc_xprt_debugfs_register(struct rpc_xprt *xprt) rpc_xprt_debugfs_register(struct rpc_xprt *xprt)
{ {
int len, id; int len, id;
static atomic_t cur_id; static atomic_t cur_id;
char name[9]; /* 8 hex digits + NULL term */ char name[9]; /* 8 hex digits + NULL term */
if (!rpc_xprt_dir)
return;
id = (unsigned int)atomic_inc_return(&cur_id); id = (unsigned int)atomic_inc_return(&cur_id);
len = snprintf(name, sizeof(name), "%x", id); len = snprintf(name, sizeof(name), "%x", id);
if (len >= sizeof(name)) if (len >= sizeof(name))
return -EINVAL; return;
/* make the per-client dir */ /* make the per-client dir */
xprt->debugfs = debugfs_create_dir(name, rpc_xprt_dir); xprt->debugfs = debugfs_create_dir(name, rpc_xprt_dir);
if (!xprt->debugfs) if (!xprt->debugfs)
return -ENOMEM; return;
/* make tasks file */ /* make tasks file */
if (!debugfs_create_file("info", S_IFREG | S_IRUSR, xprt->debugfs, if (!debugfs_create_file("info", S_IFREG | S_IRUSR, xprt->debugfs,
xprt, &xprt_info_fops)) { xprt, &xprt_info_fops)) {
debugfs_remove_recursive(xprt->debugfs); debugfs_remove_recursive(xprt->debugfs);
xprt->debugfs = NULL; xprt->debugfs = NULL;
return -ENOMEM;
} }
return 0;
} }
void void
@ -266,14 +270,17 @@ void __exit
sunrpc_debugfs_exit(void) sunrpc_debugfs_exit(void)
{ {
debugfs_remove_recursive(topdir); debugfs_remove_recursive(topdir);
topdir = NULL;
rpc_clnt_dir = NULL;
rpc_xprt_dir = NULL;
} }
int __init void __init
sunrpc_debugfs_init(void) sunrpc_debugfs_init(void)
{ {
topdir = debugfs_create_dir("sunrpc", NULL); topdir = debugfs_create_dir("sunrpc", NULL);
if (!topdir) if (!topdir)
goto out; return;
rpc_clnt_dir = debugfs_create_dir("rpc_clnt", topdir); rpc_clnt_dir = debugfs_create_dir("rpc_clnt", topdir);
if (!rpc_clnt_dir) if (!rpc_clnt_dir)
@ -283,10 +290,9 @@ sunrpc_debugfs_init(void)
if (!rpc_xprt_dir) if (!rpc_xprt_dir)
goto out_remove; goto out_remove;
return 0; return;
out_remove: out_remove:
debugfs_remove_recursive(topdir); debugfs_remove_recursive(topdir);
topdir = NULL; topdir = NULL;
out: rpc_clnt_dir = NULL;
return -ENOMEM;
} }

View File

@ -98,10 +98,7 @@ init_sunrpc(void)
if (err) if (err)
goto out4; goto out4;
err = sunrpc_debugfs_init(); sunrpc_debugfs_init();
if (err)
goto out5;
#if IS_ENABLED(CONFIG_SUNRPC_DEBUG) #if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
rpc_register_sysctl(); rpc_register_sysctl();
#endif #endif
@ -109,8 +106,6 @@ init_sunrpc(void)
init_socket_xprt(); /* clnt sock transport */ init_socket_xprt(); /* clnt sock transport */
return 0; return 0;
out5:
unregister_rpc_pipefs();
out4: out4:
unregister_pernet_subsys(&sunrpc_net_ops); unregister_pernet_subsys(&sunrpc_net_ops);
out3: out3:

View File

@ -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) struct rpc_xprt *xprt_create_transport(struct xprt_create *args)
{ {
int err;
struct rpc_xprt *xprt; struct rpc_xprt *xprt;
struct xprt_class *t; struct xprt_class *t;
@ -1372,11 +1371,7 @@ found:
return ERR_PTR(-ENOMEM); return ERR_PTR(-ENOMEM);
} }
err = rpc_xprt_debugfs_register(xprt); rpc_xprt_debugfs_register(xprt);
if (err) {
xprt_destroy(xprt);
return ERR_PTR(err);
}
dprintk("RPC: created transport %p with %u slots\n", xprt, dprintk("RPC: created transport %p with %u slots\n", xprt,
xprt->max_reqs); xprt->max_reqs);