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authorAlexey Dobriyan <adobriyan@gmail.com>2009-02-20 09:04:33 -0500
committerAlexey Dobriyan <adobriyan@gmail.com>2009-03-30 17:14:27 -0400
commit3dec7f59c370c7b58184d63293c3dc984d475840 (patch)
tree54df7ab53c1f625179e2b69c78b782b5a867363e
parent09729a9919fdaf137995b0f19cbd401e22229cac (diff)
proc 1/2: do PDE usecounting even for ->read_proc, ->write_proc
struct proc_dir_entry::owner is going to be removed. Now it's only necessary to protect PDEs which are using ->read_proc, ->write_proc hooks. However, ->owner assignments are racy and make it very easy for someone to switch ->owner on live PDE (as some subsystems do) without fixing refcounts and so on. http://bugzilla.kernel.org/show_bug.cgi?id=12454 So, ->owner is on death row. Proxy file operations exist already (proc_file_operations), just bump usecount when necessary. Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
-rw-r--r--fs/proc/generic.c48
-rw-r--r--fs/proc/inode.c2
-rw-r--r--fs/proc/internal.h1
3 files changed, 40 insertions, 11 deletions
diff --git a/fs/proc/generic.c b/fs/proc/generic.c
index 8c68bbe2b61e..fa678abc9db1 100644
--- a/fs/proc/generic.c
+++ b/fs/proc/generic.c
@@ -37,7 +37,7 @@ static int proc_match(int len, const char *name, struct proc_dir_entry *de)
37#define PROC_BLOCK_SIZE (PAGE_SIZE - 1024) 37#define PROC_BLOCK_SIZE (PAGE_SIZE - 1024)
38 38
39static ssize_t 39static ssize_t
40proc_file_read(struct file *file, char __user *buf, size_t nbytes, 40__proc_file_read(struct file *file, char __user *buf, size_t nbytes,
41 loff_t *ppos) 41 loff_t *ppos)
42{ 42{
43 struct inode * inode = file->f_path.dentry->d_inode; 43 struct inode * inode = file->f_path.dentry->d_inode;
@@ -183,19 +183,47 @@ proc_file_read(struct file *file, char __user *buf, size_t nbytes,
183} 183}
184 184
185static ssize_t 185static ssize_t
186proc_file_read(struct file *file, char __user *buf, size_t nbytes,
187 loff_t *ppos)
188{
189 struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
190 ssize_t rv = -EIO;
191
192 spin_lock(&pde->pde_unload_lock);
193 if (!pde->proc_fops) {
194 spin_unlock(&pde->pde_unload_lock);
195 return rv;
196 }
197 pde->pde_users++;
198 spin_unlock(&pde->pde_unload_lock);
199
200 rv = __proc_file_read(file, buf, nbytes, ppos);
201
202 pde_users_dec(pde);
203 return rv;
204}
205
206static ssize_t
186proc_file_write(struct file *file, const char __user *buffer, 207proc_file_write(struct file *file, const char __user *buffer,
187 size_t count, loff_t *ppos) 208 size_t count, loff_t *ppos)
188{ 209{
189 struct inode *inode = file->f_path.dentry->d_inode; 210 struct proc_dir_entry *pde = PDE(file->f_path.dentry->d_inode);
190 struct proc_dir_entry * dp; 211 ssize_t rv = -EIO;
191 212
192 dp = PDE(inode); 213 if (pde->write_proc) {
193 214 spin_lock(&pde->pde_unload_lock);
194 if (!dp->write_proc) 215 if (!pde->proc_fops) {
195 return -EIO; 216 spin_unlock(&pde->pde_unload_lock);
217 return rv;
218 }
219 pde->pde_users++;
220 spin_unlock(&pde->pde_unload_lock);
196 221
197 /* FIXME: does this routine need ppos? probably... */ 222 /* FIXME: does this routine need ppos? probably... */
198 return dp->write_proc(file, buffer, count, dp->data); 223 rv = pde->write_proc(file, buffer, count, pde->data);
224 pde_users_dec(pde);
225 }
226 return rv;
199} 227}
200 228
201 229
diff --git a/fs/proc/inode.c b/fs/proc/inode.c
index d8bb5c671f42..e11dc22c6511 100644
--- a/fs/proc/inode.c
+++ b/fs/proc/inode.c
@@ -127,7 +127,7 @@ static void __pde_users_dec(struct proc_dir_entry *pde)
127 complete(pde->pde_unload_completion); 127 complete(pde->pde_unload_completion);
128} 128}
129 129
130static void pde_users_dec(struct proc_dir_entry *pde) 130void pde_users_dec(struct proc_dir_entry *pde)
131{ 131{
132 spin_lock(&pde->pde_unload_lock); 132 spin_lock(&pde->pde_unload_lock);
133 __pde_users_dec(pde); 133 __pde_users_dec(pde);
diff --git a/fs/proc/internal.h b/fs/proc/internal.h
index cd53ff838498..f6db9618a888 100644
--- a/fs/proc/internal.h
+++ b/fs/proc/internal.h
@@ -91,3 +91,4 @@ struct pde_opener {
91 int (*release)(struct inode *, struct file *); 91 int (*release)(struct inode *, struct file *);
92 struct list_head lh; 92 struct list_head lh;
93}; 93};
94void pde_users_dec(struct proc_dir_entry *pde);