proc_create_seq_private(), proc_create_single_data() and their network namespace variants keep the seq_operations or the show function in the entry already. Let procfs own the seq_file for all of them. For the network namespace variants ->proc_open() and ->proc_release() keep taking and dropping the reference to the network namespace.
That's most of /proc/net, among them the files of xt_hashlimit and /proc/net/dev_snmp6/<dev>. A reader that faults on its buffer no longer holds up their removal. Reported-by: Chris Mason <[email protected]> Fixes: 786d7e1612f0 ("Fix rmmod/read/write races in /proc entries") Signed-off-by: Christian Brauner (Amutable) <[email protected]> --- fs/proc/generic.c | 42 ++++-------------------------------------- fs/proc/proc_net.c | 40 +++++++++++++--------------------------- 2 files changed, 17 insertions(+), 65 deletions(-) diff --git a/fs/proc/generic.c b/fs/proc/generic.c index eff5c38e2219..6ed8bc313db0 100644 --- a/fs/proc/generic.c +++ b/fs/proc/generic.c @@ -694,30 +694,9 @@ struct proc_dir_entry *proc_create(const char *name, umode_t mode, } EXPORT_SYMBOL(proc_create); -static int proc_seq_open(struct inode *inode, struct file *file) -{ - struct proc_dir_entry *de = PDE(inode); - - if (de->state_size) - return seq_open_private(file, de->seq_ops, de->state_size); - return seq_open(file, de->seq_ops); -} - -static int proc_seq_release(struct inode *inode, struct file *file) -{ - struct proc_dir_entry *de = PDE(inode); - - if (de->state_size) - return seq_release_private(inode, file); - return seq_release(inode, file); -} - +/* procfs owns the seq_file of these, see pde_seq_ops */ static const struct proc_ops proc_seq_ops = { /* not permanent -- can call into arbitrary seq_operations */ - .proc_open = proc_seq_open, - .proc_read_iter = seq_read_iter, - .proc_lseek = seq_lseek, - .proc_release = proc_seq_release, }; struct proc_dir_entry *proc_create_seq_private(const char *name, umode_t mode, @@ -732,25 +711,11 @@ struct proc_dir_entry *proc_create_seq_private(const char *name, umode_t mode, p->proc_ops = &proc_seq_ops; p->seq_ops = ops; p->state_size = state_size; + p->flags |= PROC_ENTRY_proc_seq_ops; return proc_register(parent, p); } EXPORT_SYMBOL(proc_create_seq_private); -static int proc_single_open(struct inode *inode, struct file *file) -{ - struct proc_dir_entry *de = PDE(inode); - - return single_open(file, de->single_show, de->data); -} - -static const struct proc_ops proc_single_ops = { - /* not permanent -- can call into arbitrary ->single_show */ - .proc_open = proc_single_open, - .proc_read_iter = seq_read_iter, - .proc_lseek = seq_lseek, - .proc_release = single_release, -}; - struct proc_dir_entry *proc_create_single_data(const char *name, umode_t mode, struct proc_dir_entry *parent, int (*show)(struct seq_file *, void *), void *data) @@ -760,8 +725,9 @@ struct proc_dir_entry *proc_create_single_data(const char *name, umode_t mode, p = proc_create_reg(name, mode, &parent, data); if (!p) return NULL; - p->proc_ops = &proc_single_ops; + p->proc_ops = &proc_seq_ops; p->single_show = show; + p->flags |= PROC_ENTRY_proc_show; return proc_register(parent, p); } EXPORT_SYMBOL(proc_create_single_data); diff --git a/fs/proc/proc_net.c b/fs/proc/proc_net.c index df5484813d5d..fa485581d05e 100644 --- a/fs/proc/proc_net.c +++ b/fs/proc/proc_net.c @@ -37,13 +37,13 @@ static struct net *get_proc_net(const struct inode *inode) return maybe_get_net(PDE_NET(PDE(inode))); } +/* procfs opened the seq_file and allocated its state, see pde_seq_ops */ static int seq_open_net(struct inode *inode, struct file *file) { - unsigned int state_size = PDE(inode)->state_size; - struct seq_net_private *p; + struct seq_net_private *p = ((struct seq_file *)file->private_data)->private; struct net *net; - WARN_ON_ONCE(state_size < sizeof(*p)); + WARN_ON_ONCE(PDE(inode)->state_size < sizeof(*p)); if (file->f_mode & FMODE_WRITE && !PDE(inode)->write) return -EACCES; @@ -51,12 +51,6 @@ static int seq_open_net(struct inode *inode, struct file *file) net = get_proc_net(inode); if (!net) return -ENXIO; - - p = __seq_open_private(file, PDE(inode)->seq_ops, state_size); - if (!p) { - put_net(net); - return -ENOMEM; - } #ifdef CONFIG_NET_NS p->net = net; netns_tracker_alloc(net, &p->ns_tracker, GFP_KERNEL); @@ -77,18 +71,13 @@ static void seq_file_net_put_net(struct seq_file *seq) static int seq_release_net(struct inode *ino, struct file *f) { - struct seq_file *seq = f->private_data; - - seq_file_net_put_net(seq); - seq_release_private(ino, f); + seq_file_net_put_net(f->private_data); return 0; } static const struct proc_ops proc_net_seq_ops = { .proc_open = seq_open_net, - .proc_read = seq_read, .proc_write = proc_simple_write, - .proc_lseek = seq_lseek, .proc_release = seq_release_net, }; @@ -125,6 +114,7 @@ struct proc_dir_entry *proc_create_net_data(const char *name, umode_t mode, p->proc_ops = &proc_net_seq_ops; p->seq_ops = ops; p->state_size = state_size; + p->flags |= PROC_ENTRY_proc_seq_ops; return proc_register(parent, p); } EXPORT_SYMBOL_GPL(proc_create_net_data); @@ -170,6 +160,7 @@ struct proc_dir_entry *proc_create_net_data_write(const char *name, umode_t mode p->proc_ops = &proc_net_seq_ops; p->seq_ops = ops; p->state_size = state_size; + p->flags |= PROC_ENTRY_proc_seq_ops; p->write = write; return proc_register(parent, p); } @@ -177,32 +168,25 @@ EXPORT_SYMBOL_GPL(proc_create_net_data_write); static int single_open_net(struct inode *inode, struct file *file) { - struct proc_dir_entry *de = PDE(inode); - struct net *net; - int err; + struct net *net = get_proc_net(inode); - net = get_proc_net(inode); if (!net) return -ENXIO; - - err = single_open(file, de->single_show, net); - if (err) - put_net(net); - return err; + ((struct seq_file *)file->private_data)->private = net; + return 0; } static int single_release_net(struct inode *ino, struct file *f) { struct seq_file *seq = f->private_data; + put_net(seq->private); - return single_release(ino, f); + return 0; } static const struct proc_ops proc_net_single_ops = { .proc_open = single_open_net, - .proc_read = seq_read, .proc_write = proc_simple_write, - .proc_lseek = seq_lseek, .proc_release = single_release_net, }; @@ -218,6 +202,7 @@ struct proc_dir_entry *proc_create_net_single(const char *name, umode_t mode, pde_force_lookup(p); p->proc_ops = &proc_net_single_ops; p->single_show = show; + p->flags |= PROC_ENTRY_proc_show; return proc_register(parent, p); } EXPORT_SYMBOL_GPL(proc_create_net_single); @@ -261,6 +246,7 @@ struct proc_dir_entry *proc_create_net_single_write(const char *name, umode_t mo pde_force_lookup(p); p->proc_ops = &proc_net_single_ops; p->single_show = show; + p->flags |= PROC_ENTRY_proc_show; p->write = write; return proc_register(parent, p); } -- 2.53.0
