From e9720acd728a46cb40daa52c99a979f7c4ff195c Mon Sep 17 00:00:00 2001 From: Pavel Emelyanov Date: Fri, 7 Mar 2008 11:08:40 -0800 Subject: [NET]: Make /proc/net a symlink on /proc/self/net (v3) Current /proc/net is done with so called "shadows", but current implementation is broken and has little chances to get fixed. The problem is that dentries subtree of /proc/net directory has fancy revalidation rules to make processes living in different net namespaces see different entries in /proc/net subtree, but currently, tasks see in the /proc/net subdir the contents of any other namespace, depending on who opened the file first. The proposed fix is to turn /proc/net into a symlink, which points to /proc/self/net, which in turn shows what previously was in /proc/net - the network-related info, from the net namespace the appropriate task lives in. # ls -l /proc/net lrwxrwxrwx 1 root root 8 Mar 5 15:17 /proc/net -> self/net In other words - this behaves like /proc/mounts, but unlike "mounts", "net" is not a file, but a directory. Changes from v2: * Fixed discrepancy of /proc/net nlink count and selinux labeling screwup pointed out by Stephen. To get the correct nlink count the ->getattr callback for /proc/net is overridden to read one from the net->proc_net entry. To make selinux still work the net->proc_net entry is initialized properly, i.e. with the "net" name and the proc_net parent. Selinux fixes are Acked-by: Stephen Smalley Changes from v1: * Fixed a task_struct leak in get_proc_task_net, pointed out by Paul. Signed-off-by: Pavel Emelyanov Acked-by: "Eric W. Biederman" Signed-off-by: David S. Miller --- fs/proc/generic.c | 26 +++++++++++++++++--------- 1 file changed, 17 insertions(+), 9 deletions(-) (limited to 'fs/proc/generic.c') diff --git a/fs/proc/generic.c b/fs/proc/generic.c index 68971e66cd4..a36ad3c75cf 100644 --- a/fs/proc/generic.c +++ b/fs/proc/generic.c @@ -377,15 +377,14 @@ static struct dentry_operations proc_dentry_operations = * Don't create negative dentries here, return -ENOENT by hand * instead. */ -struct dentry *proc_lookup(struct inode * dir, struct dentry *dentry, struct nameidata *nd) +struct dentry *proc_lookup_de(struct proc_dir_entry *de, struct inode *dir, + struct dentry *dentry) { struct inode *inode = NULL; - struct proc_dir_entry * de; int error = -ENOENT; lock_kernel(); spin_lock(&proc_subdir_lock); - de = PDE(dir); if (de) { for (de = de->subdir; de ; de = de->next) { if (de->namelen != dentry->d_name.len) @@ -393,8 +392,6 @@ struct dentry *proc_lookup(struct inode * dir, struct dentry *dentry, struct nam if (!memcmp(dentry->d_name.name, de->name, de->namelen)) { unsigned int ino; - if (de->shadow_proc) - de = de->shadow_proc(current, de); ino = de->low_ino; de_get(de); spin_unlock(&proc_subdir_lock); @@ -417,6 +414,12 @@ out_unlock: return ERR_PTR(error); } +struct dentry *proc_lookup(struct inode *dir, struct dentry *dentry, + struct nameidata *nd) +{ + return proc_lookup_de(PDE(dir), dir, dentry); +} + /* * This returns non-zero if at EOF, so that the /proc * root directory can use this and check if it should @@ -426,10 +429,9 @@ out_unlock: * value of the readdir() call, as long as it's non-negative * for success.. */ -int proc_readdir(struct file * filp, - void * dirent, filldir_t filldir) +int proc_readdir_de(struct proc_dir_entry *de, struct file *filp, void *dirent, + filldir_t filldir) { - struct proc_dir_entry * de; unsigned int ino; int i; struct inode *inode = filp->f_path.dentry->d_inode; @@ -438,7 +440,6 @@ int proc_readdir(struct file * filp, lock_kernel(); ino = inode->i_ino; - de = PDE(inode); if (!de) { ret = -EINVAL; goto out; @@ -499,6 +500,13 @@ out: unlock_kernel(); return ret; } +int proc_readdir(struct file *filp, void *dirent, filldir_t filldir) +{ + struct inode *inode = filp->f_path.dentry->d_inode; + + return proc_readdir_de(PDE(inode), filp, dirent, filldir); +} + /* * These are the generic /proc directory operations. They * use the in-memory "struct proc_dir_entry" tree to parse -- cgit v1.2.3