From: Miklos Szeredi GFS2 calls permission() to verify permissions after locks on the files have been taken. For this it's sufficient to call gfs2_permission() instead. This results in the following changes: - IS_RDONLY() check is not performed - IS_IMMUTABLE() check is not performed - devcgroup_inode_permission() is not called - security_inode_permission() is not called IS_RDONLY() should be unnecessary anyway, as the per-mount read-only flag should provide protection against read-only remounts during operations. do_gfs2_set_flags() has been fixed to perform mnt_want_write()/mnt_drop_write() to protect against remounting read-only. IS_IMMUTABLE has beed added to gfs2_do_permission() Repeating the security checks seems to be pointless, as they don't normally change, and if they do, it's independent of the filesystem state. I also suspect the conditional locking in gfs2_do_permission() could be cleaned up, due to the removal of the implicit recursion. Signed-off-by: Miklos Szeredi CC: Steven Whitehouse --- fs/gfs2/inode.c | 6 +++--- fs/gfs2/inode.h | 1 + fs/gfs2/ops_file.c | 11 +++++++++-- fs/gfs2/ops_inode.c | 18 +++++++++++++----- 4 files changed, 26 insertions(+), 10 deletions(-) Index: linux-2.6/fs/gfs2/inode.c =================================================================== --- linux-2.6.orig/fs/gfs2/inode.c 2008-05-21 15:45:11.000000000 +0200 +++ linux-2.6/fs/gfs2/inode.c 2008-05-21 15:45:45.000000000 +0200 @@ -504,7 +504,7 @@ struct inode *gfs2_lookupi(struct inode } if (!is_root) { - error = permission(dir, MAY_EXEC, NULL); + error = gfs2_do_permission(dir, MAY_EXEC); if (error) goto out; } @@ -667,7 +667,7 @@ static int create_ok(struct gfs2_inode * { int error; - error = permission(&dip->i_inode, MAY_WRITE | MAY_EXEC, NULL); + error = gfs2_do_permission(&dip->i_inode, MAY_WRITE | MAY_EXEC); if (error) return error; @@ -1134,7 +1134,7 @@ int gfs2_unlink_ok(struct gfs2_inode *di if (IS_APPEND(&dip->i_inode)) return -EPERM; - error = permission(&dip->i_inode, MAY_WRITE | MAY_EXEC, NULL); + error = gfs2_do_permission(&dip->i_inode, MAY_WRITE | MAY_EXEC); if (error) return error; Index: linux-2.6/fs/gfs2/inode.h =================================================================== --- linux-2.6.orig/fs/gfs2/inode.h 2008-05-21 15:45:11.000000000 +0200 +++ linux-2.6/fs/gfs2/inode.h 2008-05-21 15:45:45.000000000 +0200 @@ -91,6 +91,7 @@ int gfs2_rmdiri(struct gfs2_inode *dip, struct gfs2_inode *ip); int gfs2_unlink_ok(struct gfs2_inode *dip, const struct qstr *name, const struct gfs2_inode *ip); +int gfs2_do_permission(struct inode *inode, int mask); int gfs2_ok_to_move(struct gfs2_inode *this, struct gfs2_inode *to); int gfs2_readlinki(struct gfs2_inode *ip, char **buf, unsigned int *len); int gfs2_glock_nq_atime(struct gfs2_holder *gh); Index: linux-2.6/fs/gfs2/ops_file.c =================================================================== --- linux-2.6.orig/fs/gfs2/ops_file.c 2008-05-21 15:45:11.000000000 +0200 +++ linux-2.6/fs/gfs2/ops_file.c 2008-05-21 15:45:45.000000000 +0200 @@ -15,6 +15,7 @@ #include #include #include +#include #include #include #include @@ -220,10 +221,14 @@ static int do_gfs2_set_flags(struct file int error; u32 new_flags, flags; - error = gfs2_glock_nq_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &gh); + error = mnt_want_write(filp->f_path.mnt); if (error) return error; + error = gfs2_glock_nq_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &gh); + if (error) + goto out_drop_write; + flags = ip->i_di.di_flags; new_flags = (flags & ~mask) | (reqflags & mask); if ((new_flags ^ flags) == 0) @@ -242,7 +247,7 @@ static int do_gfs2_set_flags(struct file !capable(CAP_LINUX_IMMUTABLE)) goto out; if (!IS_IMMUTABLE(inode)) { - error = permission(inode, MAY_WRITE, NULL); + error = gfs2_do_permission(inode, MAY_WRITE); if (error) goto out; } @@ -272,6 +277,8 @@ out_trans_end: gfs2_trans_end(sdp); out: gfs2_glock_dq_uninit(&gh); +out_drop_write: + mnt_drop_write(filp->f_path.mnt); return error; } Index: linux-2.6/fs/gfs2/ops_inode.c =================================================================== --- linux-2.6.orig/fs/gfs2/ops_inode.c 2008-05-21 15:45:11.000000000 +0200 +++ linux-2.6/fs/gfs2/ops_inode.c 2008-05-21 15:55:15.000000000 +0200 @@ -163,7 +163,7 @@ static int gfs2_link(struct dentry *old_ if (error) goto out; - error = permission(dir, MAY_WRITE | MAY_EXEC, NULL); + error = gfs2_do_permission(dir, MAY_WRITE | MAY_EXEC); if (error) goto out_gunlock; @@ -669,7 +669,7 @@ static int gfs2_rename(struct inode *odi } } } else { - error = permission(ndir, MAY_WRITE | MAY_EXEC, NULL); + error = gfs2_do_permission(ndir, MAY_WRITE | MAY_EXEC); if (error) goto out_gunlock; @@ -704,7 +704,7 @@ static int gfs2_rename(struct inode *odi /* Check out the dir to be renamed */ if (dir_rename) { - error = permission(odentry->d_inode, MAY_WRITE, NULL); + error = gfs2_do_permission(odentry->d_inode, MAY_WRITE); if (error) goto out_gunlock; } @@ -891,7 +891,7 @@ static void *gfs2_follow_link(struct den * Returns: errno */ -static int gfs2_permission(struct inode *inode, int mask, struct nameidata *nd) +int gfs2_do_permission(struct inode *inode, int mask) { struct gfs2_inode *ip = GFS2_I(inode); struct gfs2_holder i_gh; @@ -905,13 +905,21 @@ static int gfs2_permission(struct inode unlock = 1; } - error = generic_permission(inode, mask, gfs2_check_acl); + if ((mask & MAY_WRITE) && IS_IMMUTABLE(inode)) + error = -EACCES; + else + error = generic_permission(inode, mask, gfs2_check_acl); if (unlock) gfs2_glock_dq_uninit(&i_gh); return error; } +static int gfs2_permission(struct inode *inode, int mask, struct nameidata *nd) +{ + return gfs2_do_permission(inode, mask); +} + static int setattr_size(struct inode *inode, struct iattr *attr) { struct gfs2_inode *ip = GFS2_I(inode); -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/