| Message ID | 52152ec4b83fe0c406475bfee39efafaaa2a88fb.1499805486.git.ernesto.mnd.fernandez@gmail.com |
|---|---|
| State | Accepted, archived |
| Headers | show |
On Wed 12-07-17 06:53:51, Ernesto A. Fernández wrote: > When changing a file's acl mask, __ext4_set_acl() will first set the group > bits of i_mode to the value of the mask, and only then set the actual > extended attribute representing the new acl. > > If the second part fails (due to lack of space, for example) and the file > had no acl attribute to begin with, the system will from now on assume > that the mask permission bits are actual group permission bits, potentially > granting access to the wrong users. > > Prevent this by only changing the inode mode after the acl has been set. > > Signed-off-by: Ernesto A. Fernández <ernesto.mnd.fernandez@gmail.com> This clashes with my fix of another bug in that area [1] but the fixup should be straightforward. The patch looks good to me so feel free to add Reviewed-by: Jan Kara <jack@suse.cz> [1] https://www.spinics.net/lists/stable/msg178111.html Honza > --- > fs/ext4/acl.c | 15 +++++++++++---- > 1 file changed, 11 insertions(+), 4 deletions(-) > > diff --git a/fs/ext4/acl.c b/fs/ext4/acl.c > index 09441ae..2985cd0 100644 > --- a/fs/ext4/acl.c > +++ b/fs/ext4/acl.c > @@ -189,16 +189,17 @@ __ext4_set_acl(handle_t *handle, struct inode *inode, int type, > void *value = NULL; > size_t size = 0; > int error; > + int update_mode = 0; > + umode_t mode = inode->i_mode; > > switch (type) { > case ACL_TYPE_ACCESS: > name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS; > if (acl) { > - error = posix_acl_update_mode(inode, &inode->i_mode, &acl); > + error = posix_acl_update_mode(inode, &mode, &acl); > if (error) > return error; > - inode->i_ctime = current_time(inode); > - ext4_mark_inode_dirty(handle, inode); > + update_mode = 1; > } > break; > > @@ -221,8 +222,14 @@ __ext4_set_acl(handle_t *handle, struct inode *inode, int type, > value, size, xattr_flags); > > kfree(value); > - if (!error) > + if (!error) { > set_cached_acl(inode, type, acl); > + if (update_mode) { > + inode->i_mode = mode; > + inode->i_ctime = current_time(inode); > + ext4_mark_inode_dirty(handle, inode); > + } > + } > > return error; > } > -- > 2.1.4 > >
On Wed, Jul 12, 2017 at 06:53:51AM -0300, Ernesto A. Fernández wrote: > When changing a file's acl mask, __ext4_set_acl() will first set the group > bits of i_mode to the value of the mask, and only then set the actual > extended attribute representing the new acl. > > If the second part fails (due to lack of space, for example) and the file > had no acl attribute to begin with, the system will from now on assume > that the mask permission bits are actual group permission bits, potentially > granting access to the wrong users. > > Prevent this by only changing the inode mode after the acl has been set. > > Signed-off-by: Ernesto A. Fernández <ernesto.mnd.fernandez@gmail.com> Thanks, applied. - Ted
diff --git a/fs/ext4/acl.c b/fs/ext4/acl.c index 09441ae..2985cd0 100644 --- a/fs/ext4/acl.c +++ b/fs/ext4/acl.c @@ -189,16 +189,17 @@ __ext4_set_acl(handle_t *handle, struct inode *inode, int type, void *value = NULL; size_t size = 0; int error; + int update_mode = 0; + umode_t mode = inode->i_mode; switch (type) { case ACL_TYPE_ACCESS: name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS; if (acl) { - error = posix_acl_update_mode(inode, &inode->i_mode, &acl); + error = posix_acl_update_mode(inode, &mode, &acl); if (error) return error; - inode->i_ctime = current_time(inode); - ext4_mark_inode_dirty(handle, inode); + update_mode = 1; } break; @@ -221,8 +222,14 @@ __ext4_set_acl(handle_t *handle, struct inode *inode, int type, value, size, xattr_flags); kfree(value); - if (!error) + if (!error) { set_cached_acl(inode, type, acl); + if (update_mode) { + inode->i_mode = mode; + inode->i_ctime = current_time(inode); + ext4_mark_inode_dirty(handle, inode); + } + } return error; }
When changing a file's acl mask, __ext4_set_acl() will first set the group bits of i_mode to the value of the mask, and only then set the actual extended attribute representing the new acl. If the second part fails (due to lack of space, for example) and the file had no acl attribute to begin with, the system will from now on assume that the mask permission bits are actual group permission bits, potentially granting access to the wrong users. Prevent this by only changing the inode mode after the acl has been set. Signed-off-by: Ernesto A. Fernández <ernesto.mnd.fernandez@gmail.com> --- fs/ext4/acl.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-)