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authorAl Viro <viro@zeniv.linux.org.uk>2015-02-21 22:16:11 -0500
committerAl Viro <viro@zeniv.linux.org.uk>2015-02-22 11:43:12 -0500
commit7e0e953bb0cf649f93277ac8fb67ecbb7f7b04a9 (patch)
tree1ba29a05213aefe77827f268624948ad417c984a
parent0db59e59299f0b67450c5db21f7f316c8fb04e84 (diff)
downloadlinux-7e0e953bb0cf649f93277ac8fb67ecbb7f7b04a9.tar.gz
procfs: fix race between symlink removals and traversals
use_pde()/unuse_pde() in ->follow_link()/->put_link() resp. Cc: stable@vger.kernel.org Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
-rw-r--r--fs/proc/generic.c12
-rw-r--r--fs/proc/inode.c21
-rw-r--r--fs/proc/internal.h1
3 files changed, 22 insertions, 12 deletions
diff --git a/fs/proc/generic.c b/fs/proc/generic.c
index 3309f59..be65b20 100644
--- a/fs/proc/generic.c
+++ b/fs/proc/generic.c
@@ -19,7 +19,6 @@
#include <linux/mount.h>
#include <linux/init.h>
#include <linux/idr.h>
-#include <linux/namei.h>
#include <linux/bitops.h>
#include <linux/spinlock.h>
#include <linux/completion.h>
@@ -223,17 +222,6 @@ void proc_free_inum(unsigned int inum)
spin_unlock_irqrestore(&proc_inum_lock, flags);
}
-static void *proc_follow_link(struct dentry *dentry, struct nameidata *nd)
-{
- nd_set_link(nd, __PDE_DATA(dentry->d_inode));
- return NULL;
-}
-
-static const struct inode_operations proc_link_inode_operations = {
- .readlink = generic_readlink,
- .follow_link = proc_follow_link,
-};
-
/*
* Don't create negative dentries here, return -ENOENT by hand
* instead.
diff --git a/fs/proc/inode.c b/fs/proc/inode.c
index 13a50a3..7697b66 100644
--- a/fs/proc/inode.c
+++ b/fs/proc/inode.c
@@ -23,6 +23,7 @@
#include <linux/slab.h>
#include <linux/mount.h>
#include <linux/magic.h>
+#include <linux/namei.h>
#include <asm/uaccess.h>
@@ -393,6 +394,26 @@ static const struct file_operations proc_reg_file_ops_no_compat = {
};
#endif
+static void *proc_follow_link(struct dentry *dentry, struct nameidata *nd)
+{
+ struct proc_dir_entry *pde = PDE(dentry->d_inode);
+ if (unlikely(!use_pde(pde)))
+ return ERR_PTR(-EINVAL);
+ nd_set_link(nd, pde->data);
+ return pde;
+}
+
+static void proc_put_link(struct dentry *dentry, struct nameidata *nd, void *p)
+{
+ unuse_pde(p);
+}
+
+const struct inode_operations proc_link_inode_operations = {
+ .readlink = generic_readlink,
+ .follow_link = proc_follow_link,
+ .put_link = proc_put_link,
+};
+
struct inode *proc_get_inode(struct super_block *sb, struct proc_dir_entry *de)
{
struct inode *inode = new_inode_pseudo(sb);
diff --git a/fs/proc/internal.h b/fs/proc/internal.h
index 6fcdba5..c835b94 100644
--- a/fs/proc/internal.h
+++ b/fs/proc/internal.h
@@ -200,6 +200,7 @@ struct pde_opener {
int closing;
struct completion *c;
};
+extern const struct inode_operations proc_link_inode_operations;
extern const struct inode_operations proc_pid_link_inode_operations;