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author | Al Viro <viro@zeniv.linux.org.uk> | 2018-05-03 03:26:16 +0200 |
---|---|---|
committer | Al Viro <viro@zeniv.linux.org.uk> | 2018-05-22 20:28:03 +0200 |
commit | 1bbc55131e59bd099fdc568d3aa0b42634dbd188 (patch) | |
tree | 42f965fe9a163a3bdaf8d8a51a6649afbf7118ce /fs/proc | |
parent | cifs_lookup(): switch to d_splice_alias() (diff) | |
download | linux-1bbc55131e59bd099fdc568d3aa0b42634dbd188.tar.xz linux-1bbc55131e59bd099fdc568d3aa0b42634dbd188.zip |
procfs: get rid of ancient BS in pid_revalidate() uses
First of all, calling pid_revalidate() in the end of <pid>/* lookups
is *not* about closing any kind of races; that used to be true once
upon a time, but these days those comments are actively misleading.
Especially since pid_revalidate() doesn't even do d_drop() on
failure anymore. It doesn't matter, anyway, since once
pid_revalidate() starts returning false, ->d_delete() of those
dentries starts saying "don't keep"; they won't get stuck in
dcache any longer than they are pinned.
These calls cannot be just removed, though - the side effect of
pid_revalidate() (updating i_uid/i_gid/etc.) is what we are calling
it for here.
Let's separate the "update ownership" into a new helper (pid_update_inode())
and use it, both in lookups and in pid_revalidate() itself.
The comments in pid_revalidate() are also out of date - they refer to
the time when pid_revalidate() used to call d_drop() directly...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/proc')
-rw-r--r-- | fs/proc/base.c | 55 | ||||
-rw-r--r-- | fs/proc/internal.h | 2 | ||||
-rw-r--r-- | fs/proc/namespaces.c | 9 |
3 files changed, 28 insertions, 38 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c index eafa39a3a88c..6e0875505898 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -1803,15 +1803,22 @@ int pid_getattr(const struct path *path, struct kstat *stat, /* dentry stuff */ /* - * Exceptional case: normally we are not allowed to unhash a busy - * directory. In this case, however, we can do it - no aliasing problems - * due to the way we treat inodes. - * + * Set <pid>/... inode ownership (can change due to setuid(), etc.) + */ +void pid_update_inode(struct task_struct *task, struct inode *inode) +{ + task_dump_owner(task, inode->i_mode, &inode->i_uid, &inode->i_gid); + + inode->i_mode &= ~(S_ISUID | S_ISGID); + security_task_to_inode(task, inode); +} + +/* * Rewrite the inode's ownerships here because the owning task may have * performed a setuid(), etc. * */ -int pid_revalidate(struct dentry *dentry, unsigned int flags) +static int pid_revalidate(struct dentry *dentry, unsigned int flags) { struct inode *inode; struct task_struct *task; @@ -1823,10 +1830,7 @@ int pid_revalidate(struct dentry *dentry, unsigned int flags) task = get_proc_task(inode); if (task) { - task_dump_owner(task, inode->i_mode, &inode->i_uid, &inode->i_gid); - - inode->i_mode &= ~(S_ISUID | S_ISGID); - security_task_to_inode(task, inode); + pid_update_inode(task, inode); put_task_struct(task); return 1; } @@ -2438,7 +2442,7 @@ static int proc_pident_instantiate(struct inode *dir, inode = proc_pid_make_inode(dir->i_sb, task, p->mode); if (!inode) - goto out; + return -ENOENT; ei = PROC_I(inode); if (S_ISDIR(inode->i_mode)) @@ -2448,13 +2452,10 @@ static int proc_pident_instantiate(struct inode *dir, if (p->fop) inode->i_fop = p->fop; ei->op = p->op; + pid_update_inode(task, inode); d_set_d_op(dentry, &pid_dentry_operations); d_add(dentry, inode); - /* Close the race of the process dying before we return the dentry */ - if (pid_revalidate(dentry, 0)) - return 0; -out: - return -ENOENT; + return 0; } static struct dentry *proc_pident_lookup(struct inode *dir, @@ -3140,22 +3141,18 @@ static int proc_pid_instantiate(struct inode *dir, inode = proc_pid_make_inode(dir->i_sb, task, S_IFDIR | S_IRUGO | S_IXUGO); if (!inode) - goto out; + return -ENOENT; inode->i_op = &proc_tgid_base_inode_operations; inode->i_fop = &proc_tgid_base_operations; inode->i_flags|=S_IMMUTABLE; set_nlink(inode, nlink_tgid); + pid_update_inode(task, inode); d_set_d_op(dentry, &pid_dentry_operations); - d_add(dentry, inode); - /* Close the race of the process dying before we return the dentry */ - if (pid_revalidate(dentry, 0)) - return 0; -out: - return -ENOENT; + return 0; } struct dentry *proc_pid_lookup(struct inode *dir, struct dentry * dentry, unsigned int flags) @@ -3434,23 +3431,19 @@ static int proc_task_instantiate(struct inode *dir, { struct inode *inode; inode = proc_pid_make_inode(dir->i_sb, task, S_IFDIR | S_IRUGO | S_IXUGO); - if (!inode) - goto out; + return -ENOENT; + inode->i_op = &proc_tid_base_inode_operations; inode->i_fop = &proc_tid_base_operations; - inode->i_flags|=S_IMMUTABLE; + inode->i_flags |= S_IMMUTABLE; set_nlink(inode, nlink_tid); + pid_update_inode(task, inode); d_set_d_op(dentry, &pid_dentry_operations); - d_add(dentry, inode); - /* Close the race of the process dying before we return the dentry */ - if (pid_revalidate(dentry, 0)) - return 0; -out: - return -ENOENT; + return 0; } static struct dentry *proc_task_lookup(struct inode *dir, struct dentry * dentry, unsigned int flags) diff --git a/fs/proc/internal.h b/fs/proc/internal.h index 0f1692e63cb6..04a455b9ae69 100644 --- a/fs/proc/internal.h +++ b/fs/proc/internal.h @@ -147,7 +147,7 @@ extern const struct dentry_operations pid_dentry_operations; extern int pid_getattr(const struct path *, struct kstat *, u32, unsigned int); extern int proc_setattr(struct dentry *, struct iattr *); extern struct inode *proc_pid_make_inode(struct super_block *, struct task_struct *, umode_t); -extern int pid_revalidate(struct dentry *, unsigned int); +extern void pid_update_inode(struct task_struct *, struct inode *); extern int pid_delete_dentry(const struct dentry *); extern int proc_pid_readdir(struct file *, struct dir_context *); extern struct dentry *proc_pid_lookup(struct inode *, struct dentry *, unsigned int); diff --git a/fs/proc/namespaces.c b/fs/proc/namespaces.c index 59b17e509f46..ad1adce6541d 100644 --- a/fs/proc/namespaces.c +++ b/fs/proc/namespaces.c @@ -96,19 +96,16 @@ static int proc_ns_instantiate(struct inode *dir, inode = proc_pid_make_inode(dir->i_sb, task, S_IFLNK | S_IRWXUGO); if (!inode) - goto out; + return -ENOENT; ei = PROC_I(inode); inode->i_op = &proc_ns_link_inode_operations; ei->ns_ops = ns_ops; + pid_update_inode(task, inode); d_set_d_op(dentry, &pid_dentry_operations); d_add(dentry, inode); - /* Close the race of the process dying before we return the dentry */ - if (pid_revalidate(dentry, 0)) - return 0; -out: - return -ENOENT; + return 0; } static int proc_ns_dir_readdir(struct file *file, struct dir_context *ctx) |