kernel/include/linux/sysctl.h, branch linux-4.8.y

sysctl: handle error writing UINT_MAX to u32 fields

2016-08-27T00:39:35Z

We have scripts which write to certain fields on 3.18 kernels but this seems to be failing on 4.4 kernels. An entry which we write to here is xfrm_aevent_rseqth which is u32. echo 4294967295 > /proc/sys/net/core/xfrm_aevent_rseqth Commit 230633d109e3 ("kernel/sysctl.c: detect overflows when converting to int") prevented writing to sysctl entries when integer overflow occurs. However, this does not apply to unsigned integers. Heinrich suggested that we introduce a new option to handle 64 bit limits and set min as 0 and max as UINT_MAX. This might not work as it leads to issues similar to __do_proc_doulongvec_minmax. Alternatively, we would need to change the datatype of the entry to 64 bit. static int __do_proc_doulongvec_minmax(void *data, struct ctl_table { i = (unsigned long *) data; //This cast is causing to read beyond the size of data (u32) vleft = table->maxlen / sizeof(unsigned long); //vleft is 0 because maxlen is sizeof(u32) which is lesser than sizeof(unsigned long) on x86_64. Introduce a new proc handler proc_douintvec. Individual proc entries will need to be updated to use the new handler. [akpm@linux-foundation.org: coding-style fixes] Fixes: 230633d109e3 ("kernel/sysctl.c:detect overflows when converting to int") Link: http://lkml.kernel.org/r/1471479806-5252-1-git-send-email-subashab@codeaurora.org Signed-off-by: Subash Abhinov Kasiviswanathan Cc: Heinrich Schuchardt Cc: Kees Cook Cc: "David S. Miller" Cc: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

uapi: move forward declarations of internal structures

2016-08-02T21:31:41Z

Don't user forward declarations of internal kernel structures in headers exported to userspace. Move "struct completion;". Move "struct task_struct;". Link: http://lkml.kernel.org/r/20160713215808.GA22486@p183.telecom.by Signed-off-by: Alexey Dobriyan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

sysctl: Allow creating permanently empty directories that serve as mountpoints.

2015-07-01T15:36:39Z

Add a magic sysctl table sysctl_mount_point that when used to create a directory forces that directory to be permanently empty. Update the code to use make_empty_dir_inode when accessing permanently empty directories. Update the code to not allow adding to permanently empty directories. Update /proc/sys/fs/binfmt_misc to be a permanently empty directory. Cc: stable@vger.kernel.org Signed-off-by: "Eric W. Biederman"

kernel/sysctl.c: threads-max observe limits

2015-04-17T13:04:07Z

Users can change the maximum number of threads by writing to /proc/sys/kernel/threads-max. With the patch the value entered is checked against the same limits that apply when fork_init is called. Signed-off-by: Heinrich Schuchardt Cc: Oleg Nesterov Cc: Ingo Molnar Cc: Guenter Roeck Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

sysctl: remove typedef ctl_table

2014-08-08T22:57:24Z

Remove the final user, and the typedef itself. Signed-off-by: Joe Perches Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

sysctl: Pass useful parameters to sysctl permissions

2012-11-19T01:30:55Z

- Current is implicitly avaiable so passing current->nsproxy isn't useful. - The ctl_table_header is needed to find how the sysctl table is connected to the rest of sysctl. - ctl_table_root is avaiable in the ctl_table_header so no need to it. With these changes it becomes possible to write a version of net_sysctl_permission that takes into account the network namespace of the sysctl table, an important feature in extending the user namespace. Acked-by: Serge Hallyn Signed-off-by: "Eric W. Biederman" Signed-off-by: David S. Miller

UAPI: (Scripted) Disintegrate include/linux

2012-10-13T09:46:48Z

Signed-off-by: David Howells Acked-by: Arnd Bergmann Acked-by: Thomas Gleixner Acked-by: Michael Kerrisk Acked-by: Paul E. McKenney Acked-by: Dave Jones

sysctl: Add register_sysctl for normal sysctl users

2012-01-25T00:40:30Z

The plan is to convert all callers of register_sysctl_table and register_sysctl_paths to register_sysctl. The interface to register_sysctl is enough nicer this should make the callers a bit more readable. Additionally after the conversion the 230 lines of backwards compatibility can be removed. Signed-off-by: Eric W. Biederman

sysctl: Index sysctl directories with rbtrees.

2012-01-25T00:40:30Z

One of the most important jobs of sysctl is to export network stack tunables. Several of those tunables are per network device. In several instances people are running with 1000+ network devices in there network stacks, which makes the simple per directory linked list in sysctl a scaling bottleneck. Replace O(N^2) sysctl insertion and lookup times with O(NlogN) by using an rbtree to index the sysctl directories. Benchmark before: make-dummies 0 999 -> 0.32s rmmod dummy -> 0.12s make-dummies 0 9999 -> 1m17s rmmod dummy -> 17s Benchmark after: make-dummies 0 999 -> 0.074s rmmod dummy -> 0.070s make-dummies 0 9999 -> 3.4s rmmod dummy -> 0.44s Benchmark after (without dev_snmp6): make-dummies 0 9999 -> 0.75s rmmod dummy -> 0.44s make-dummies 0 99999 -> 11s rmmod dummy -> 4.3s At 10,000 dummy devices the bottleneck becomes the time to add and remove the files under /proc/sys/net/dev_snmp6. I have commented out the code that adds and removes files under /proc/sys/net/dev_snmp6 and taken measurments of creating and destroying 100,000 dummies to verify the sysctl continues to scale. Signed-off-by: Eric W. Biederman

sysctl: Make the header lists per directory.

2012-01-25T00:40:30Z

Slightly enhance efficiency and clarity of the code by making the header list per directory instead of per set. Benchmark before: make-dummies 0 999 -> 0.63s rmmod dummy -> 0.12s make-dummies 0 9999 -> 2m35s rmmod dummy -> 18s Benchmark after: make-dummies 0 999 -> 0.32s rmmod dummy -> 0.12s make-dummies 0 9999 -> 1m17s rmmod dummy -> 17s Signed-off-by: Eric W. Biederman