The patch titled
Subject: sysctl: kdoc'ify sysctl_writes_strict
has been added to the -mm tree. Its filename is
sysctl-kdocify-sysctl_writes_strict.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/sysctl-kdocify-sysctl_writes_strict.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/sysctl-kdocify-sysctl_writes_strict.patch
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------------------------------------------------------
From: "Luis R. Rodriguez" <mcgrof@xxxxxxxxxx>
Subject: sysctl: kdoc'ify sysctl_writes_strict
Document the different sysctl_writes_strict modes in code.
Link: http://lkml.kernel.org/r/20170519033554.18592-3-mcgrof@xxxxxxxxxx
Signed-off-by: Luis R. Rodriguez <mcgrof@xxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Cc: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/sysctl.c | 29 +++++++++++++++++++++++++----
1 file changed, 25 insertions(+), 4 deletions(-)
diff -puN kernel/sysctl.c~sysctl-kdocify-sysctl_writes_strict kernel/sysctl.c
--- a/kernel/sysctl.c~sysctl-kdocify-sysctl_writes_strict
+++ a/kernel/sysctl.c
@@ -174,11 +174,32 @@ extern int no_unaligned_warning;
#ifdef CONFIG_PROC_SYSCTL
-#define SYSCTL_WRITES_LEGACY -1
-#define SYSCTL_WRITES_WARN 0
-#define SYSCTL_WRITES_STRICT 1
+/**
+ * enum sysctl_writes_mode - supported sysctl write modes
+ *
+ * @SYSCTL_WRITES_LEGACY: each write syscall must fully contain the sysctl value
+ * to be written, and multiple writes on the same sysctl file descriptor
+ * will rewrite the sysctl value, regardless of file position. No warning
+ * is issued when the initial position is not 0.
+ * @SYSCTL_WRITES_WARN: same as above but warn when the initial file position is
+ * not 0.
+ * @SYSCTL_WRITES_STRICT: writes to numeric sysctl entries must always be at
+ * file position 0 and the value must be fully contained in the buffer
+ * sent to the write syscall. If dealing with strings respect the file
+ * position, but restrict this to the max length of the buffer, anything
+ * passed the max lenght will be ignored. Multiple writes will append
+ * to the buffer.
+ *
+ * These write modes control how current file position affects the behavior of
+ * updating sysctl values through the proc interface on each write.
+ */
+enum sysctl_writes_mode {
+ SYSCTL_WRITES_LEGACY = -1,
+ SYSCTL_WRITES_WARN = 0,
+ SYSCTL_WRITES_STRICT = 1,
+};
-static int sysctl_writes_strict = SYSCTL_WRITES_STRICT;
+static enum sysctl_writes_mode sysctl_writes_strict = SYSCTL_WRITES_STRICT;
static int proc_do_cad_pid(struct ctl_table *table, int write,
void __user *buffer, size_t *lenp, loff_t *ppos);
_
Patches currently in -mm which might be from mcgrof@xxxxxxxxxx are
sysctl-fix-lax-sysctl_check_table-sanity-check.patch
sysctl-kdocify-sysctl_writes_strict.patch
sysctl-fold-sysctl_writes_strict-checks-into-helper.patch
sysctl-simplify-unsigned-int-support.patch
sysctl-add-unsigned-int-range-support.patch
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