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    Subject[v2 073/115] sysctl: group root-specific operations
    Date
    No functional change, just moved stuff around.

    ->lookup was not moved to _ops because we'll get rid of it later.

    This makes ctl_table_set occupy less space (the pointer to is_seen),
    and that will means N*sizeof(void*) saved for N network
    namespaces, but I don't that will impress anyone.

    Signed-off-by: Lucian Adrian Grijincu <lucian.grijincu@gmail.com>
    ---
    fs/proc/proc_sysctl.c | 4 ++--
    include/linux/sysctl.h | 26 +++++++++++++++++++-------
    kernel/sysctl.c | 25 ++++++++++++++-----------
    net/sysctl_net.c | 20 ++++++++++++++------
    4 files changed, 49 insertions(+), 26 deletions(-)

    diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
    index 125b679..55c9bd1 100644
    --- a/fs/proc/proc_sysctl.c
    +++ b/fs/proc/proc_sysctl.c
    @@ -131,7 +131,7 @@ static ssize_t proc_sys_call_handler(struct file *filp, void __user *buf,
    * and won't be until we finish.
    */
    error = -EPERM;
    - if (sysctl_perm(head->root, table, write ? MAY_WRITE : MAY_READ))
    + if (sysctl_perm(head->root->ctl_ops, table, write ? MAY_WRITE : MAY_READ))
    goto out;

    /* if that can happen at all, it should be -EINVAL, not -EISDIR */
    @@ -305,7 +305,7 @@ static int proc_sys_permission(struct inode *inode, int mask,unsigned int flags)
    if (!table) /* global root - r-xr-xr-x */
    error = mask & MAY_WRITE ? -EACCES : 0;
    else /* Use the permissions on the sysctl table entry */
    - error = sysctl_perm(head->root, table, mask);
    + error = sysctl_perm(head->root->ctl_ops, table, mask);

    sysctl_unuse_header(head);
    return error;
    diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
    index 1af4ed5..8209d75 100644
    --- a/include/linux/sysctl.h
    +++ b/include/linux/sysctl.h
    @@ -934,22 +934,21 @@ enum

    /* For the /proc/sys support */
    struct ctl_table;
    +struct ctl_table_header;
    +struct ctl_table_group_ops;
    struct nsproxy;
    struct ctl_table_root;

    struct ctl_table_set {
    struct list_head list;
    struct ctl_table_set *parent;
    - int (*is_seen)(struct ctl_table_set *);
    };

    extern __init int sysctl_init(void);

    extern void setup_sysctl_set(struct ctl_table_set *p,
    - struct ctl_table_set *parent,
    - int (*is_seen)(struct ctl_table_set *));
    + struct ctl_table_set *parent);

    -struct ctl_table_header;

    /* get/put a reference to this header that
    * will be/was embedded in a procfs proc_inode */
    @@ -962,8 +961,8 @@ extern struct ctl_table_header *sysctl_use_next_header(struct ctl_table_header *
    extern struct ctl_table_header *__sysctl_use_next_header(struct nsproxy *namespaces,
    struct ctl_table_header *prev);
    extern void sysctl_unuse_header(struct ctl_table_header *prev);
    -extern int sysctl_perm(struct ctl_table_root *root,
    - struct ctl_table *table, int op);
    +extern int sysctl_perm(const struct ctl_table_group_ops *ops,
    + struct ctl_table *table, int op);

    typedef struct ctl_table ctl_table;

    @@ -1029,12 +1028,25 @@ struct ctl_table
    void *extra2;
    };

    +struct ctl_table_group_ops {
    + /* some sysctl entries are visible only in some situations.
    + * E.g.: /proc/sys/net/ipv4/conf/eth0/ is only visible in the
    + * netns in which that eth0 interface lives.
    + *
    + * If this hook is not set, then all the sysctl entries in
    + * this set are always visible. */
    + int (*is_seen)(struct ctl_table_set *set);
    +
    + /* hook to alter permissions for some sysctl nodes at runtime */
    + int (*permissions)(struct ctl_table *table);
    +};
    +
    struct ctl_table_root {
    struct list_head root_list;
    struct ctl_table_set default_set;
    struct ctl_table_set *(*lookup)(struct ctl_table_root *root,
    struct nsproxy *namespaces);
    - int (*permissions)(struct ctl_table *table);
    + const struct ctl_table_group_ops *ctl_ops;
    };

    /* struct ctl_table_header is used to maintain dynamic lists of
    diff --git a/kernel/sysctl.c b/kernel/sysctl.c
    index 6e4e32b..0f00b87 100644
    --- a/kernel/sysctl.c
    +++ b/kernel/sysctl.c
    @@ -197,6 +197,9 @@ static int sysrq_sysctl_handler(ctl_table *table, int write,

    #endif

    +/* uses default ops */
    +static const struct ctl_table_group_ops root_table_group_ops = { };
    +
    static struct ctl_table root_table[];
    static struct ctl_table_root sysctl_table_root;
    static struct ctl_table_header root_table_header = {
    @@ -206,7 +209,9 @@ static struct ctl_table_header root_table_header = {
    .root = &sysctl_table_root,
    .set = &sysctl_table_root.default_set,
    };
    +
    static struct ctl_table_root sysctl_table_root = {
    + .ctl_ops = &root_table_group_ops,
    .root_list = LIST_HEAD_INIT(sysctl_table_root.root_list),
    .default_set.list = LIST_HEAD_INIT(root_table_header.ctl_entry),
    };
    @@ -1659,12 +1664,13 @@ static int test_perm(int mode, int op)
    return -EACCES;
    }

    -int sysctl_perm(struct ctl_table_root *root, struct ctl_table *table, int op)
    +int sysctl_perm(const struct ctl_table_group_ops *ops,
    + struct ctl_table *table, int op)
    {
    int mode;

    - if (root->permissions)
    - mode = root->permissions(table);
    + if (ops->permissions)
    + mode = ops->permissions(table);
    else
    mode = table->mode;

    @@ -1950,26 +1956,24 @@ void unregister_sysctl_table(struct ctl_table_header * header)

    int sysctl_is_seen(struct ctl_table_header *p)
    {
    - struct ctl_table_set *set = p->set;
    + const struct ctl_table_group_ops *ops = p->root->ctl_ops;
    int res;
    spin_lock(&sysctl_lock);
    if (p->unregistering)
    res = 0;
    - else if (!set->is_seen)
    + else if (!ops->is_seen)
    res = 1;
    else
    - res = set->is_seen(set);
    + res = ops->is_seen(p->set);
    spin_unlock(&sysctl_lock);
    return res;
    }

    void setup_sysctl_set(struct ctl_table_set *p,
    - struct ctl_table_set *parent,
    - int (*is_seen)(struct ctl_table_set *))
    + struct ctl_table_set *parent)
    {
    INIT_LIST_HEAD(&p->list);
    p->parent = parent ? parent : &sysctl_table_root.default_set;
    - p->is_seen = is_seen;
    }

    #else /* !CONFIG_SYSCTL */
    @@ -1984,8 +1988,7 @@ void unregister_sysctl_table(struct ctl_table_header * table)
    }

    void setup_sysctl_set(struct ctl_table_set *p,
    - struct ctl_table_set *parent,
    - int (*is_seen)(struct ctl_table_set *))
    + struct ctl_table_set *parent)
    {
    }

    diff --git a/net/sysctl_net.c b/net/sysctl_net.c
    index 1c0cb57..c0d7140 100644
    --- a/net/sysctl_net.c
    +++ b/net/sysctl_net.c
    @@ -51,12 +51,17 @@ static int net_ctl_permissions(struct ctl_table *table)
    return table->mode;
    }

    +static const struct ctl_table_group_ops net_sysctl_group_ops = {
    + .is_seen = is_seen,
    + .permissions = net_ctl_permissions,
    +};
    +
    static struct ctl_table_root net_sysctl_root = {
    .lookup = net_ctl_header_lookup,
    - .permissions = net_ctl_permissions,
    + .ctl_ops = &net_sysctl_group_ops,
    };

    -static int net_ctl_ro_header_perms(ctl_table *table)
    +static int net_ctl_ro_header_permissions(ctl_table *table)
    {
    if (net_eq(current->nsproxy->net_ns, &init_net))
    return table->mode;
    @@ -64,15 +69,18 @@ static int net_ctl_ro_header_perms(ctl_table *table)
    return table->mode & ~0222;
    }

    +static const struct ctl_table_group_ops net_sysctl_ro_group_ops = {
    + .permissions = net_ctl_ro_header_permissions,
    +};
    +
    static struct ctl_table_root net_sysctl_ro_root = {
    - .permissions = net_ctl_ro_header_perms,
    + .ctl_ops = &net_sysctl_ro_group_ops,
    };

    static int __net_init sysctl_net_init(struct net *net)
    {
    setup_sysctl_set(&net->sysctls,
    - &net_sysctl_ro_root.default_set,
    - is_seen);
    + &net_sysctl_ro_root.default_set);
    return 0;
    }

    @@ -93,7 +101,7 @@ static __init int net_sysctl_init(void)
    if (ret)
    goto out;
    register_sysctl_root(&net_sysctl_root);
    - setup_sysctl_set(&net_sysctl_ro_root.default_set, NULL, NULL);
    + setup_sysctl_set(&net_sysctl_ro_root.default_set, NULL);
    register_sysctl_root(&net_sysctl_ro_root);
    out:
    return ret;
    --
    1.7.5.134.g1c08b


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