[PATCH V3 3/6] namespaces: expose ns instance serial numbers in proc

Richard Guy Briggs
2014-05-20T13:12:54Z

Expose the namespace instace serial numbers in the proc filesystem at
/proc/<pid>/ns/<ns>_snum. The link text gives the serial number in hex.

"snum" was chosen instead of "seq" for consistency with inum and there are a
number of other uses of "seq" in the namespace code.

Suggested-by: Serge E. Hallyn <serge@hallyn.com>
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
---
fs/proc/namespaces.c | 33 +++++++++++++++++++++++++--------
1 files changed, 25 insertions(+), 8 deletions(-)

diff --git a/fs/proc/namespaces.c b/fs/proc/namespaces.c
index 9ae46b8..57fce90 100644
--- a/fs/proc/namespaces.c
+++ b/fs/proc/namespaces.c
@@ -47,12 +47,15 @@ static char *ns_dname(struct dentry *dentry, char *buffer, int buflen)
struct inode *inode = dentry->d_inode;
const struct proc_ns_operations *ns_ops = PROC_I(inode)->ns.ns_ops;

- return dynamic_dname(dentry, buffer, buflen, "%s:[%lu]",
- ns_ops->name, inode->i_ino);
+ if (strstr(dentry->d_iname, "_snum"))
+ return dynamic_dname(dentry, buffer, buflen, "%s_snum:[%llx]",
+ ns_ops->name, ns_ops->snum(PROC_I(inode)->ns.ns));
+ else
+ return dynamic_dname(dentry, buffer, buflen, "%s:[%lu]",
+ ns_ops->name, inode->i_ino);
}

-const struct dentry_operations ns_dentry_operations =
-{
+const struct dentry_operations ns_dentry_operations = {
.d_delete = always_delete_dentry,
.d_dname = ns_dname,
};
@@ -160,7 +163,10 @@ static int proc_ns_readlink(struct dentry *dentry, char __user *buffer, int bufl
if (!ns)
goto out_put_task;

- snprintf(name, sizeof(name), "%s:[%u]", ns_ops->name, ns_ops->inum(ns));
+ if (strstr(dentry->d_iname, "_snum"))
+ snprintf(name, sizeof(name), "%s_snum:[%llx]", ns_ops->name, ns_ops->snum(ns));
+ else
+ snprintf(name, sizeof(name), "%s:[%u]", ns_ops->name, ns_ops->inum(ns));
len = strlen(name);

if (len > buflen)
@@ -216,16 +222,23 @@ static int proc_ns_dir_readdir(struct file *file, struct dir_context *ctx)

if (!dir_emit_dots(file, ctx))
goto out;
- if (ctx->pos >= 2 + ARRAY_SIZE(ns_entries))
+ if (ctx->pos >= 2 + 2 * ARRAY_SIZE(ns_entries))
goto out;
entry = ns_entries + (ctx->pos - 2);
last = &ns_entries[ARRAY_SIZE(ns_entries) - 1];
while (entry <= last) {
const struct proc_ns_operations *ops = *entry;
+ char name[50];
+
if (!proc_fill_cache(file, ctx, ops->name, strlen(ops->name),
proc_ns_instantiate, task, ops))
break;
ctx->pos++;
+ snprintf(name, sizeof(name), "%s_snum", ops->name);
+ if (!proc_fill_cache(file, ctx, name, strlen(name),
+ proc_ns_instantiate, task, ops))
+ break;
+ ctx->pos++;
entry++;
}
out:
@@ -253,9 +266,13 @@ static struct dentry *proc_ns_dir_lookup(struct inode *dir,

last = &ns_entries[ARRAY_SIZE(ns_entries)];
for (entry = ns_entries; entry < last; entry++) {
- if (strlen((*entry)->name) != len)
+ char name[50];
+
+ snprintf(name, sizeof(name), "%s_snum", (*entry)->name);
+ if (strlen((*entry)->name) != len && strlen(name) != len)
continue;
- if (!memcmp(dentry->d_name.name, (*entry)->name, len))
+ if (!memcmp(dentry->d_name.name, (*entry)->name, len)
+ || !memcmp(dentry->d_name.name, name, len))
break;
}
if (entry == last)
--
1.7.1