Make notify_change not clear the ATTR_KILL_S*ID bits in the ia_vaid that
gets passed to the setattr inode operation. This allows the filesystems
to reinterpret whether this mode change is simply intended to clear the
setuid/setgid bits.
This means that notify_change should never be called with both ATTR_MODE
and either of the ATTR_KILL_S*ID bits set, since the filesystem would
have no way to know what part of the mode change was intentional. If
it is called this way, consider it a BUG().
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
---
fs/attr.c | 23 +++++++++++++----------
1 files changed, 13 insertions(+), 10 deletions(-)
diff --git a/fs/attr.c b/fs/attr.c
index ae58bd3..6b3b07e 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 = inode->i_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;
@@ -125,18 +124,22 @@ int notify_change(struct dentry * dentry, struct iattr * attr)
if (error)
return error;
}
+
+ /*
+ * It's not valid to pass an iattr with both ATTR_MODE and
+ * ATTR_KILL_S*ID set.
+ */
+ if ((ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID)) &&
+ (ia_valid & ATTR_MODE))
+ BUG();
+
if (ia_valid & ATTR_KILL_SUID) {
- attr->ia_valid &= ~ATTR_KILL_SUID;
if (mode & S_ISUID) {
- if (!(ia_valid & ATTR_MODE)) {
- ia_valid = attr->ia_valid |= ATTR_MODE;
- attr->ia_mode = inode->i_mode;
- }
- attr->ia_mode &= ~S_ISUID;
+ ia_valid = attr->ia_valid |= ATTR_MODE;
+ attr->ia_mode = (inode->i_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)) {
if (!(ia_valid & ATTR_MODE)) {
ia_valid = attr->ia_valid |= ATTR_MODE;
@@ -145,7 +148,7 @@ int notify_change(struct dentry * dentry, struct iattr * attr)
attr->ia_mode &= ~S_ISGID;
}
}
- if (!attr->ia_valid)
+ if (!(attr->ia_valid & ~(ATTR_KILL_SUID | ATTR_KILL_SGID)))
return 0;
if (ia_valid & ATTR_SIZE)
--
1.5.2.1
-
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