This patch adds the killattr inode operation. inodes that have a
killattr operation defined are responsible for properly handling the
ATTR_KILL_SUID and ATTR_KILL_SGID bits within this operation. inodes
that do not have a killattr op will instead use "standard" logic which
turns these bits into a mode change if the setuid or setgid bits are
currently set in the inode's mode.
To enable this, the patch does the standard processing of these bits on
a set of local variables, and then has these local variables supercede
the values in the iattr when a killattr op isn't defined.
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
fs/attr.c | 33 ++++++++++++++++++++-------------
include/linux/fs.h | 1 +
2 files changed, 21 insertions(+), 13 deletions(-)
diff --git a/fs/attr.c b/fs/attr.c
index ae58bd3..77608d3 100644
--- a/fs/attr.c
+++ b/fs/attr.c
@@ -103,12 +103,11 @@ EXPORT_SYMBOL(inode_setattr);
int notify_change(struct dentry * dentry, struct iattr * attr)
{
struct inode *inode = dentry->d_inode;
- mode_t mode;
+ mode_t mode = attr->ia_mode;
int error;
struct timespec now;
unsigned int ia_valid = attr->ia_valid;
- mode = inode->i_mode;
now = current_fs_time(inode->i_sb);
attr->ia_ctime = now;
@@ -126,28 +125,36 @@ int notify_change(struct dentry * dentry, struct iattr * attr)
return error;
}
if (ia_valid & ATTR_KILL_SUID) {
- attr->ia_valid &= ~ATTR_KILL_SUID;
- if (mode & S_ISUID) {
+ ia_valid &= ~ATTR_KILL_SUID;
+ if (inode->i_mode & S_ISUID) {
if (!(ia_valid & ATTR_MODE)) {
- ia_valid = attr->ia_valid |= ATTR_MODE;
- attr->ia_mode = inode->i_mode;
+ ia_valid |= ATTR_MODE;
+ mode = inode->i_mode;
}
- attr->ia_mode &= ~S_ISUID;
+ mode &= ~S_ISUID;
}
}
if (ia_valid & ATTR_KILL_SGID) {
- attr->ia_valid &= ~ ATTR_KILL_SGID;
- if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
+ ia_valid &= ~ATTR_KILL_SGID;
+ if ((inode->i_mode & (S_ISGID | S_IXGRP)) ==
+ (S_ISGID | S_IXGRP)) {
if (!(ia_valid & ATTR_MODE)) {
- ia_valid = attr->ia_valid |= ATTR_MODE;
- attr->ia_mode = inode->i_mode;
+ ia_valid |= ATTR_MODE;
+ mode = inode->i_mode;
}
- attr->ia_mode &= ~S_ISGID;
+ mode &= ~S_ISGID;
}
}
- if (!attr->ia_valid)
+ if (!ia_valid)
return 0;
+ if (inode->i_op && inode->i_op->killattr) {
+ inode->i_op->killattr(dentry, attr);
+ } else {
+ attr->ia_valid = ia_valid;
+ attr->ia_mode = mode;
+ }
+
if (ia_valid & ATTR_SIZE)
down_write(&dentry->d_inode->i_alloc_sem);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 291d40b..d213539 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1220,6 +1220,7 @@ struct inode_operations {
void (*truncate_range)(struct inode *, loff_t, loff_t);
long (*fallocate)(struct inode *inode, int mode, loff_t offset,
loff_t len);
+ void (*killattr) (struct dentry *dentry, struct iattr *attr);
};
struct seq_file;
--
1.5.2.1
-
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