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(Nokia - FI/Espoo)" , Al Viro , Andrew Morton , Linus Torvalds , Sasha Levin Subject: [PATCH 5.10 458/717] proc: fix lookup in /proc/net subdirectories after setns(2) Date: Mon, 28 Dec 2020 13:47:36 +0100 Message-Id: <20201228125042.911923213@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201228125020.963311703@linuxfoundation.org> References: <20201228125020.963311703@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Alexey Dobriyan [ Upstream commit c6c75deda81344c3a95d1d1f606d5cee109e5d54 ] Commit 1fde6f21d90f ("proc: fix /proc/net/* after setns(2)") only forced revalidation of regular files under /proc/net/ However, /proc/net/ is unusual in the sense of /proc/net/foo handlers take netns pointer from parent directory which is old netns. Steps to reproduce: (void)open("/proc/net/sctp/snmp", O_RDONLY); unshare(CLONE_NEWNET); int fd = open("/proc/net/sctp/snmp", O_RDONLY); read(fd, &c, 1); Read will read wrong data from original netns. Patch forces lookup on every directory under /proc/net . Link: https://lkml.kernel.org/r/20201205160916.GA109739@localhost.localdomain Fixes: 1da4d377f943 ("proc: revalidate misc dentries") Signed-off-by: Alexey Dobriyan Reported-by: "Rantala, Tommi T. (Nokia - FI/Espoo)" Cc: Al Viro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- fs/proc/generic.c | 24 ++++++++++++++++++++++-- fs/proc/internal.h | 7 +++++++ fs/proc/proc_net.c | 16 ---------------- include/linux/proc_fs.h | 8 +++++++- 4 files changed, 36 insertions(+), 19 deletions(-) diff --git a/fs/proc/generic.c b/fs/proc/generic.c index b84663252adda..6c0a05f55d6b1 100644 --- a/fs/proc/generic.c +++ b/fs/proc/generic.c @@ -349,6 +349,16 @@ static const struct file_operations proc_dir_operations = { .iterate_shared = proc_readdir, }; +static int proc_net_d_revalidate(struct dentry *dentry, unsigned int flags) +{ + return 0; +} + +const struct dentry_operations proc_net_dentry_ops = { + .d_revalidate = proc_net_d_revalidate, + .d_delete = always_delete_dentry, +}; + /* * proc directories can do almost nothing.. */ @@ -471,8 +481,8 @@ struct proc_dir_entry *proc_symlink(const char *name, } EXPORT_SYMBOL(proc_symlink); -struct proc_dir_entry *proc_mkdir_data(const char *name, umode_t mode, - struct proc_dir_entry *parent, void *data) +struct proc_dir_entry *_proc_mkdir(const char *name, umode_t mode, + struct proc_dir_entry *parent, void *data, bool force_lookup) { struct proc_dir_entry *ent; @@ -484,10 +494,20 @@ struct proc_dir_entry *proc_mkdir_data(const char *name, umode_t mode, ent->data = data; ent->proc_dir_ops = &proc_dir_operations; ent->proc_iops = &proc_dir_inode_operations; + if (force_lookup) { + pde_force_lookup(ent); + } ent = proc_register(parent, ent); } return ent; } +EXPORT_SYMBOL_GPL(_proc_mkdir); + +struct proc_dir_entry *proc_mkdir_data(const char *name, umode_t mode, + struct proc_dir_entry *parent, void *data) +{ + return _proc_mkdir(name, mode, parent, data, false); +} EXPORT_SYMBOL_GPL(proc_mkdir_data); struct proc_dir_entry *proc_mkdir_mode(const char *name, umode_t mode, diff --git a/fs/proc/internal.h b/fs/proc/internal.h index 917cc85e34663..afbe96b6bf77d 100644 --- a/fs/proc/internal.h +++ b/fs/proc/internal.h @@ -310,3 +310,10 @@ extern unsigned long task_statm(struct mm_struct *, unsigned long *, unsigned long *, unsigned long *, unsigned long *); extern void task_mem(struct seq_file *, struct mm_struct *); + +extern const struct dentry_operations proc_net_dentry_ops; +static inline void pde_force_lookup(struct proc_dir_entry *pde) +{ + /* /proc/net/ entries can be changed under us by setns(CLONE_NEWNET) */ + pde->proc_dops = &proc_net_dentry_ops; +} diff --git a/fs/proc/proc_net.c b/fs/proc/proc_net.c index ed8a6306990c4..1aa9236bf1af5 100644 --- a/fs/proc/proc_net.c +++ b/fs/proc/proc_net.c @@ -39,22 +39,6 @@ static struct net *get_proc_net(const struct inode *inode) return maybe_get_net(PDE_NET(PDE(inode))); } -static int proc_net_d_revalidate(struct dentry *dentry, unsigned int flags) -{ - return 0; -} - -static const struct dentry_operations proc_net_dentry_ops = { - .d_revalidate = proc_net_d_revalidate, - .d_delete = always_delete_dentry, -}; - -static void pde_force_lookup(struct proc_dir_entry *pde) -{ - /* /proc/net/ entries can be changed under us by setns(CLONE_NEWNET) */ - pde->proc_dops = &proc_net_dentry_ops; -} - static int seq_open_net(struct inode *inode, struct file *file) { unsigned int state_size = PDE(inode)->state_size; diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h index 270cab43ca3da..000cc0533c336 100644 --- a/include/linux/proc_fs.h +++ b/include/linux/proc_fs.h @@ -80,6 +80,7 @@ extern void proc_flush_pid(struct pid *); extern struct proc_dir_entry *proc_symlink(const char *, struct proc_dir_entry *, const char *); +struct proc_dir_entry *_proc_mkdir(const char *, umode_t, struct proc_dir_entry *, void *, bool); extern struct proc_dir_entry *proc_mkdir(const char *, struct proc_dir_entry *); extern struct proc_dir_entry *proc_mkdir_data(const char *, umode_t, struct proc_dir_entry *, void *); @@ -162,6 +163,11 @@ static inline struct proc_dir_entry *proc_symlink(const char *name, static inline struct proc_dir_entry *proc_mkdir(const char *name, struct proc_dir_entry *parent) {return NULL;} static inline struct proc_dir_entry *proc_create_mount_point(const char *name) { return NULL; } +static inline struct proc_dir_entry *_proc_mkdir(const char *name, umode_t mode, + struct proc_dir_entry *parent, void *data, bool force_lookup) +{ + return NULL; +} static inline struct proc_dir_entry *proc_mkdir_data(const char *name, umode_t mode, struct proc_dir_entry *parent, void *data) { return NULL; } static inline struct proc_dir_entry *proc_mkdir_mode(const char *name, @@ -199,7 +205,7 @@ struct net; static inline struct proc_dir_entry *proc_net_mkdir( struct net *net, const char *name, struct proc_dir_entry *parent) { - return proc_mkdir_data(name, 0, parent, net); + return _proc_mkdir(name, 0, parent, net, true); } struct ns_common; -- 2.27.0