Messages in this thread Patch in this message | | | From | (Eric W. Biederman) | Date | Thu, 06 Nov 2008 02:56:09 -0800 | Subject | [PATCH 5/7] proc_net: Don't show the wrong /proc/net after unshare. |
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This is accomplished by dropping the /proc/<pid>/net dentry when we discover an older version of /proc/net is mounted upon it. This prevents new lookups from using the mount and ultimately proc_shrink_automounts will catch up with it and remove the old mount point.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> --- fs/proc/base.c | 11 +++++++---- fs/proc/internal.h | 11 +++++++++++ fs/proc/proc_net.c | 33 +++++++++++++++++++++++++++++++++ 3 files changed, 51 insertions(+), 4 deletions(-)
diff --git a/fs/proc/base.c b/fs/proc/base.c index 9a68fa4..8b0d066 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -1487,6 +1487,7 @@ static int pid_revalidate(struct dentry *dentry, struct nameidata *nd) { struct inode *inode = dentry->d_inode; struct task_struct *task = get_proc_task(inode); + int ret = 0; if (task) { if ((inode->i_mode == (S_IFDIR|S_IRUGO|S_IXUGO)) || task_dumpable(task)) { @@ -1497,12 +1498,14 @@ static int pid_revalidate(struct dentry *dentry, struct nameidata *nd) inode->i_gid = 0; } inode->i_mode &= ~(S_ISUID | S_ISGID); - security_task_to_inode(task, inode); + ret = proc_net_revalidate(task, dentry, nd); + if (ret == 1) + security_task_to_inode(task, inode); put_task_struct(task); - return 1; } - d_drop(dentry); - return 0; + if (ret == 0) + d_drop(dentry); + return ret; } static int pid_delete_dentry(struct dentry * dentry) diff --git a/fs/proc/internal.h b/fs/proc/internal.h index ffa285e..f9f8de6 100644 --- a/fs/proc/internal.h +++ b/fs/proc/internal.h @@ -64,6 +64,17 @@ extern const struct file_operations proc_kmsg_operations; extern const struct file_operations proc_net_operations; extern const struct inode_operations proc_net_inode_operations; +#ifdef CONFIG_NET +extern int proc_net_revalidate(struct task_struct *task, struct dentry *dentry, + struct nameidata *nd); +#else +static inline int proc_net_revalidate(struct task_struct *t, struct dentry *d, + struct nameidata *nd) +{ + return 1; +} +#endif + void free_proc_entry(struct proc_dir_entry *de); void proc_init_inodecache(void); diff --git a/fs/proc/proc_net.c b/fs/proc/proc_net.c index 57e0f22..4a7551a 100644 --- a/fs/proc/proc_net.c +++ b/fs/proc/proc_net.c @@ -174,6 +174,39 @@ const struct inode_operations proc_net_inode_operations = { .follow_link = proc_net_follow_link, }; +int proc_net_revalidate(struct task_struct *task, struct dentry *dentry, + struct nameidata *nd) +{ + struct inode *inode = dentry->d_inode; + struct dentry *tdentry; + struct vfsmount *tmnt; + int ret = 1; + + /* Are we talking about a proc/net mount point? */ + if (!nd || (inode->i_op != &proc_net_inode_operations)) + goto out; + + /* If the wrong filesystem is mounted on + * /proc/<pid>/net report the dentry is invalid. + */ + tdentry = dget(dentry); + tmnt = mntget(nd->path.mnt); + if (follow_down(&tmnt, &tdentry)) { + struct nsproxy *ns; + rcu_read_lock(); + ns = task_nsproxy(task); + if ((ns == NULL) || + (tmnt->mnt_sb->s_magic != PROC_NET_SUPER_MAGIC) || + (tmnt->mnt_sb->s_fs_info != ns->net_ns)) + ret = 0; + rcu_read_unlock(); + } + mntput(tmnt); + dput(tdentry); +out: + return ret; +} + struct proc_dir_entry *proc_net_fops_create(struct net *net, const char *name, mode_t mode, const struct file_operations *fops) { -- 1.5.3.rc6.17.g1911
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