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    Subject[patch v2] gfs2: don't call permission()
    From
    Date
    This is the updated version, with the promised renames:

    gfs2_do_permission -> gfs2_permission
    gfs2_permission -> gfs2_iop_permission

    Thanks,
    Miklos

    ----
    From: Miklos Szeredi <mszeredi@suse.cz>

    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 been added to gfs2_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.

    Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
    ---
    fs/gfs2/inode.c | 6 +++---
    fs/gfs2/inode.h | 1 +
    fs/gfs2/ops_file.c | 11 +++++++++--
    fs/gfs2/ops_inode.c | 25 +++++++++++++++++--------
    4 files changed, 30 insertions(+), 13 deletions(-)

    Index: linux-2.6/fs/gfs2/inode.c
    ===================================================================
    --- linux-2.6.orig/fs/gfs2/inode.c 2008-07-01 18:11:32.000000000 +0200
    +++ linux-2.6/fs/gfs2/inode.c 2008-07-01 19:15:59.000000000 +0200
    @@ -504,7 +504,7 @@ struct inode *gfs2_lookupi(struct inode
    }

    if (!is_root) {
    - error = permission(dir, MAY_EXEC, NULL);
    + error = gfs2_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_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_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 2008-07-01 18:11:32.000000000 +0200
    +++ linux-2.6/fs/gfs2/inode.h 2008-07-01 19:15:59.000000000 +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_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 2008-07-01 18:11:32.000000000 +0200
    +++ linux-2.6/fs/gfs2/ops_file.c 2008-07-01 19:15:59.000000000 +0200
    @@ -15,6 +15,7 @@
    #include <linux/uio.h>
    #include <linux/blkdev.h>
    #include <linux/mm.h>
    +#include <linux/mount.h>
    #include <linux/fs.h>
    #include <linux/gfs2_ondisk.h>
    #include <linux/ext2_fs.h>
    @@ -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_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 2008-07-01 18:11:32.000000000 +0200
    +++ linux-2.6/fs/gfs2/ops_inode.c 2008-07-01 19:15:59.000000000 +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_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_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_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_permission(struct inode *inode, int mask)
    {
    struct gfs2_inode *ip = GFS2_I(inode);
    struct gfs2_holder i_gh;
    @@ -905,13 +905,22 @@ 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_iop_permission(struct inode *inode, int mask,
    + struct nameidata *nd)
    +{
    + return gfs2_permission(inode, mask);
    +}
    +
    static int setattr_size(struct inode *inode, struct iattr *attr)
    {
    struct gfs2_inode *ip = GFS2_I(inode);
    @@ -1141,7 +1150,7 @@ static int gfs2_removexattr(struct dentr
    }

    const struct inode_operations gfs2_file_iops = {
    - .permission = gfs2_permission,
    + .permission = gfs2_iop_permission,
    .setattr = gfs2_setattr,
    .getattr = gfs2_getattr,
    .setxattr = gfs2_setxattr,
    @@ -1160,7 +1169,7 @@ const struct inode_operations gfs2_dir_i
    .rmdir = gfs2_rmdir,
    .mknod = gfs2_mknod,
    .rename = gfs2_rename,
    - .permission = gfs2_permission,
    + .permission = gfs2_iop_permission,
    .setattr = gfs2_setattr,
    .getattr = gfs2_getattr,
    .setxattr = gfs2_setxattr,
    @@ -1172,7 +1181,7 @@ const struct inode_operations gfs2_dir_i
    const struct inode_operations gfs2_symlink_iops = {
    .readlink = gfs2_readlink,
    .follow_link = gfs2_follow_link,
    - .permission = gfs2_permission,
    + .permission = gfs2_iop_permission,
    .setattr = gfs2_setattr,
    .getattr = gfs2_getattr,
    .setxattr = gfs2_setxattr,

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