Re: [PATCH V4 3/8] namespaces: expose ns instance serial numbers in proc
From: Andy Lutomirski <hidden>
Date: 2014-08-21 21:13:52
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lkml
On Aug 20, 2014 8:12 PM, "Richard Guy Briggs" [off-list ref] wrote:
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.
What's the use case? I understand the utility of giving unique numbers to the audit code, but I don't think this part is necessary for that, and I'd like to understand what else will use this before committing to a duplicative API like this. Note that this API is thoroughly incompatible with CRIU. If we do this, someone will ask for a namespace number namespace, and that way lies madness. --Andy
quoted hunk ↗ jump to hunk
"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 <redacted> Signed-off-by: Richard Guy Briggs <redacted> --- 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 8902609..e953e0a 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)); res = readlink_copy(buffer, buflen, name); ns_ops->put(ns); out_put_task:@@ -210,16 +216,23 @@ 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:@@ -247,9 +260,13 @@ 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 -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html