The patch titled
sysctl: merge equal proc_sys_read and proc_sys_write
has been added to the -mm tree. Its filename is
sysctl-merge-equal-proc_sys_read-and-proc_sys_write.patch
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------------------------------------------------------
Subject: sysctl: merge equal proc_sys_read and proc_sys_write
From: Pavel Emelyanov <xemul@xxxxxxxxxx>
Many (most of) sysctls do not have a per-container sense. E.g.
kernel.print_fatal_signals, vm.panic_on_oom, net.core.netdev_budget and so on
and so forth. Besides, tuning then from inside a container is not even
secure. On the other hand, hiding them completely from the container's tasks
sometimes causes user-space to stop working.
When developing net sysctl, the common practice was to duplicate a table and
drop the write bits in table->mode, but this approach was not very elegant,
lead to excessive memory consumption and was not suitable in general.
Here's the alternative solution. To facilitate the per-container sysctls
ctl_table_root-s were introduced. Each root contains a list of
ctl_table_header-s that are visible to different namespaces. The idea of this
set is to add the permissions() callback on the ctl_table_root to allow ctl
root limit permissions to the same ctl_table-s.
The main user of this functionality is the net-namespaces code, but later this
will (should) be used by more and more namespaces, containers and control
groups.
Actually, this idea's core is in a single hunk in the third patch. First two
patches are cleanups for sysctl code, while the third one mostly extends the
arguments set of some sysctl functions.
This patch:
These ->read and ->write callbacks act in a very similar way, so merge these
paths to reduce the number of places to patch later and shrink the .text size
(a bit).
Signed-off-by: Pavel Emelyanov <xemul@xxxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: Alexey Dobriyan <adobriyan@xxxxx>
Cc: Denis V. Lunev <den@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/proc_sysctl.c | 50 ++++++++--------------------------------
1 file changed, 11 insertions(+), 39 deletions(-)
diff -puN fs/proc/proc_sysctl.c~sysctl-merge-equal-proc_sys_read-and-proc_sys_write fs/proc/proc_sysctl.c
--- a/fs/proc/proc_sysctl.c~sysctl-merge-equal-proc_sys_read-and-proc_sys_write
+++ a/fs/proc/proc_sysctl.c
@@ -165,8 +165,8 @@ out:
return err;
}
-static ssize_t proc_sys_read(struct file *filp, char __user *buf,
- size_t count, loff_t *ppos)
+static ssize_t proc_sys_call_handler(struct file *filp, void __user *buf,
+ size_t count, loff_t *ppos, int write)
{
struct dentry *dentry = filp->f_dentry;
struct ctl_table_header *head;
@@ -190,12 +190,12 @@ static ssize_t proc_sys_read(struct file
* and won't be until we finish.
*/
error = -EPERM;
- if (sysctl_perm(table, MAY_READ))
+ if (sysctl_perm(table, write ? MAY_WRITE : MAY_READ))
goto out;
/* careful: calling conventions are nasty here */
res = count;
- error = table->proc_handler(table, 0, filp, buf, &res, ppos);
+ error = table->proc_handler(table, write, filp, buf, &res, ppos);
if (!error)
error = res;
out:
@@ -204,44 +204,16 @@ out:
return error;
}
-static ssize_t proc_sys_write(struct file *filp, const char __user *buf,
+static ssize_t proc_sys_read(struct file *filp, char __user *buf,
size_t count, loff_t *ppos)
{
- struct dentry *dentry = filp->f_dentry;
- struct ctl_table_header *head;
- struct ctl_table *table;
- ssize_t error;
- size_t res;
-
- table = do_proc_sys_lookup(dentry->d_parent, &dentry->d_name, &head);
- /* Has the sysctl entry disappeared on us? */
- error = -ENOENT;
- if (!table)
- goto out;
-
- /* Has the sysctl entry been replaced by a directory? */
- error = -EISDIR;
- if (!table->proc_handler)
- goto out;
-
- /*
- * At this point we know that the sysctl was not unregistered
- * and won't be until we finish.
- */
- error = -EPERM;
- if (sysctl_perm(table, MAY_WRITE))
- goto out;
-
- /* careful: calling conventions are nasty here */
- res = count;
- error = table->proc_handler(table, 1, filp, (char __user *)buf,
- &res, ppos);
- if (!error)
- error = res;
-out:
- sysctl_head_finish(head);
+ return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 0);
+}
- return error;
+static ssize_t proc_sys_write(struct file *filp, const char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ return proc_sys_call_handler(filp, (void __user *)buf, count, ppos, 1);
}
_
Patches currently in -mm which might be from xemul@xxxxxxxxxx are
control-groups-add-paul-menage-a-maintainer.patch
add-balbir-as-the-maintainer-for-memory-resource-controller.patch
use-find_task_by_vpid-in-audit-code.patch
ia64-fix-ptrace-inside-a-namespace.patch
udf-fix-anchor-point-detection.patch
cgroup-api-files-rename-read-write_uint-methods-to-read_write_u64.patch
cgroup-api-files-add-res_counter_read_u64.patch
cgroup-api-files-use-read_u64-in-memory-controller.patch
cgroup-api-files-strip-all-trailing-whitespace-in-cgroup_write_u64.patch
cgroup-api-files-update-cpusets-to-use-cgroup-structured-file-api.patch
cgroup-api-files-update-cpusets-to-use-cgroup-structured-file-api-fix.patch
cgroup-api-files-add-cgroup-map-data-type.patch
cgroup-api-files-use-cgroup-map-for-memcontrol-stats-file.patch
cgroup-api-files-drop-mem_cgroup_force_empty.patch
cgroup-api-files-move-releasable-to-cgroup_debug-subsystem.patch
cgroup-api-files-make-cgroup_debug-default-to-off.patch
remove-unused-variable-from-send_signal.patch
turn-legacy_queue-macro-into-static-inline-function.patch
consolidate-checking-for-ignored-legacy-signals.patch
consolidate-checking-for-ignored-legacy-signals-simplify.patch
signals-consolidate-checks-for-whether-or-not-to-ignore-a-signal.patch
signals-clean-dequeue_signal-from-excess-checks-and-assignments.patch
signals-consolidate-send_sigqueue-and-send_group_sigqueue.patch
signals-cleanup-security_task_kill-usage-implementation.patch
sysctl-merge-equal-proc_sys_read-and-proc_sys_write.patch
sysctl-clean-from-unneeded-extern-and-forward-declarations.patch
sysctl-add-the-permissions-callback-on-the-ctl_table_root.patch
free_pidmap-turn-it-into-free_pidmapstruct-upid.patch
use-find_task_by_vpid-in-taskstats.patch
deprecate-find_task_by_pid.patch
pidns-make-pid-level-and-pid_ns-level-unsigned.patch
reiser4.patch
put_pid-make-sure-we-dont-free-the-live-pid.patch
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