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Message-Id: <20251217-jag-no-macro-conv-v1-4-6e4252687915@kernel.org>
Date: Wed, 17 Dec 2025 09:04:42 +0100
From: Joel Granados <joel.granados@...nel.org>
To: Kees Cook <kees@...nel.org>, Alexander Viro <viro@...iv.linux.org.uk>,
Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>
Cc: linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
Joel Granados <joel.granados@...nel.org>
Subject: [PATCH 4/7] sysctl: Replace UINT converter macros with functions
Replace the SYSCTL_USER_TO_KERN_UINT_CONV and SYSCTL_UINT_CONV_CUSTOM
macros with functions with the same logic. This makes debugging easier
and aligns with the functions preference described in coding-style.rst.
Update the only user of this API: pipe.c.
Signed-off-by: Joel Granados <joel.granados@...nel.org>
---
fs/pipe.c | 22 ++++++--
include/linux/sysctl.h | 63 +++-------------------
kernel/sysctl.c | 140 +++++++++++++++++++++++++++++++++++++++++++------
3 files changed, 148 insertions(+), 77 deletions(-)
diff --git a/fs/pipe.c b/fs/pipe.c
index 9e6a01475815986ea2511868f66f4a8763978578..22647f50b286d3bca024ee4c6de51b100ddc5402 100644
--- a/fs/pipe.c
+++ b/fs/pipe.c
@@ -1481,10 +1481,24 @@ static struct file_system_type pipe_fs_type = {
};
#ifdef CONFIG_SYSCTL
-static SYSCTL_USER_TO_KERN_UINT_CONV(_pipe_maxsz, round_pipe_size)
-static SYSCTL_UINT_CONV_CUSTOM(_pipe_maxsz,
- sysctl_user_to_kern_uint_conv_pipe_maxsz,
- sysctl_kern_to_user_uint_conv, true)
+
+static ulong round_pipe_size_ul(ulong size)
+{
+ return round_pipe_size(size);
+}
+
+static int u2k_pipe_maxsz(const ulong *u_ptr, uint *k_ptr)
+{
+ return proc_uint_u2k_conv_uop(u_ptr, k_ptr, round_pipe_size_ul);
+}
+
+static int do_proc_uint_conv_pipe_maxsz(ulong *u_ptr, uint *k_ptr,
+ int dir, const struct ctl_table *table)
+{
+ return proc_uint_conv(u_ptr, k_ptr, dir, table, true,
+ u2k_pipe_maxsz,
+ proc_uint_k2u_conv);
+}
static int proc_dopipe_max_size(const struct ctl_table *table, int write,
void *buffer, size_t *lenp, loff_t *ppos)
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 0a64212a0ceb8454ae343831739831a092b6e693..d712992789f0f2f3fe4cec10fb14907b7fd61a7e 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -135,45 +135,6 @@ int do_proc_int_conv##name(bool *negp, unsigned long *u_ptr, int *k_ptr,\
return user_to_kern(negp, u_ptr, k_ptr); \
return 0; \
}
-
-#define SYSCTL_USER_TO_KERN_UINT_CONV(name, u_ptr_op) \
-int sysctl_user_to_kern_uint_conv##name(const unsigned long *u_ptr,\
- unsigned int *k_ptr) \
-{ \
- unsigned long u = u_ptr_op(*u_ptr); \
- if (u > UINT_MAX) \
- return -EINVAL; \
- WRITE_ONCE(*k_ptr, u); \
- return 0; \
-}
-
-#define SYSCTL_UINT_CONV_CUSTOM(name, user_to_kern, kern_to_user, \
- k_ptr_range_check) \
-int do_proc_uint_conv##name(unsigned long *u_ptr, unsigned int *k_ptr, \
- int dir, const struct ctl_table *tbl) \
-{ \
- if (SYSCTL_KERN_TO_USER(dir)) \
- return kern_to_user(u_ptr, k_ptr); \
- \
- if (k_ptr_range_check) { \
- unsigned int tmp_k; \
- int ret; \
- if (!tbl) \
- return -EINVAL; \
- ret = user_to_kern(u_ptr, &tmp_k); \
- if (ret) \
- return ret; \
- if ((tbl->extra1 && \
- *(unsigned int *)tbl->extra1 > tmp_k) || \
- (tbl->extra2 && \
- *(unsigned int *)tbl->extra2 < tmp_k)) \
- return -ERANGE; \
- WRITE_ONCE(*k_ptr, tmp_k); \
- } else \
- return user_to_kern(u_ptr, k_ptr); \
- return 0; \
-}
-
#else // CONFIG_PROC_SYSCTL
#define SYSCTL_USER_TO_KERN_INT_CONV(name, u_ptr_op) \
int sysctl_user_to_kern_int_conv##name(const bool *negp, \
@@ -199,24 +160,8 @@ int do_proc_int_conv##name(bool *negp, unsigned long *u_ptr, int *k_ptr,\
return -ENOSYS; \
}
-#define SYSCTL_USER_TO_KERN_UINT_CONV(name, u_ptr_op) \
-int sysctl_user_to_kern_uint_conv##name(const unsigned long *u_ptr,\
- unsigned int *k_ptr) \
-{ \
- return -ENOSYS; \
-}
-
-#define SYSCTL_UINT_CONV_CUSTOM(name, user_to_kern, kern_to_user, \
- k_ptr_range_check) \
-int do_proc_uint_conv##name(unsigned long *u_ptr, unsigned int *k_ptr, \
- int dir, const struct ctl_table *tbl) \
-{ \
- return -ENOSYS; \
-}
-
#endif // CONFIG_PROC_SYSCTL
-
extern const unsigned long sysctl_long_vals[];
typedef int proc_handler(const struct ctl_table *ctl, int write, void *buffer,
@@ -239,6 +184,13 @@ int proc_douintvec_conv(const struct ctl_table *table, int write, void *buffer,
size_t *lenp, loff_t *ppos,
int (*conv)(unsigned long *lvalp, unsigned int *valp,
int write, const struct ctl_table *table));
+int proc_uint_k2u_conv(ulong *u_ptr, const uint *k_ptr);
+int proc_uint_u2k_conv_uop(const ulong *u_ptr, uint *k_ptr,
+ ulong (*u_ptr_op)(const ulong));
+int proc_uint_conv(ulong *u_ptr, uint *k_ptr, int dir,
+ const struct ctl_table *tbl, bool k_ptr_range_check,
+ int (*user_to_kern)(const ulong *u_ptr, uint *k_ptr),
+ int (*kern_to_user)(ulong *u_ptr, const uint *k_ptr));
int proc_dou8vec_minmax(const struct ctl_table *table, int write, void *buffer,
size_t *lenp, loff_t *ppos);
@@ -249,7 +201,6 @@ int proc_doulongvec_minmax_conv(const struct ctl_table *table, int dir,
int proc_do_large_bitmap(const struct ctl_table *, int, void *, size_t *, loff_t *);
int proc_do_static_key(const struct ctl_table *table, int write, void *buffer,
size_t *lenp, loff_t *ppos);
-int sysctl_kern_to_user_uint_conv(unsigned long *u_ptr, const unsigned int *k_ptr);
/*
* Register a set of sysctl names by calling register_sysctl
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index e82716b7c13840cadc3b19a7c9d05b167abebcf6..5901196a52f98cdd5aba4f50899a58d9bd9d10f9 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -354,6 +354,110 @@ static void proc_put_char(void **buf, size_t *size, char c)
}
}
+/**
+ * proc_uint_u2k_conv_uop - Assign user value to a kernel pointer
+ *
+ * @u_ptr: pointer to user space variable
+ * @k_ptr: pointer to kernel variable
+ * @u_ptr_op: execute this function before assigning to k_ptr
+ *
+ * Uses WRITE_ONCE to assign value to k_ptr. Executes u_ptr_op if
+ * not NULL. Check that the values are less than UINT_MAX to avoid
+ * having to support wrap around from userspace.
+ *
+ * returns 0 on success.
+ */
+int proc_uint_u2k_conv_uop(const ulong *u_ptr, uint *k_ptr,
+ ulong (*u_ptr_op)(const ulong))
+{
+ ulong u = u_ptr_op ? u_ptr_op(*u_ptr) : *u_ptr;
+
+ if (u > UINT_MAX)
+ return -EINVAL;
+ WRITE_ONCE(*k_ptr, u);
+ return 0;
+}
+
+/**
+ * proc_uint_k2u_conv - Assign kernel value to a user space pointer
+ *
+ * @u_ptr: pointer to user space variable
+ * @k_ptr: pointer to kernel variable
+ *
+ * Uses READ_ONCE to assign value to u_ptr.
+ *
+ * returns 0 on success.
+ */
+int proc_uint_k2u_conv(ulong *u_ptr, const uint *k_ptr)
+{
+ uint val = READ_ONCE(*k_ptr);
+ *u_ptr = (ulong)val;
+ return 0;
+}
+
+/**
+ * proc_uint_conv - Change user or kernel pointer based on direction
+ *
+ * @u_ptr: pointer to user variable
+ * @k_ptr: pointer to kernel variable
+ * @dir: %TRUE if this is a write to the sysctl file
+ * @tbl: the sysctl table
+ * @k_ptr_range_check: Check range for k_ptr when %TRUE
+ * @user_to_kern: Callback used to assign value from user to kernel var
+ * @kern_to_user: Callback used to assign value from kernel to user var
+ *
+ * When direction is kernel to user, then the u_ptr is modified.
+ * When direction is user to kernel, then the k_ptr is modified.
+ *
+ * Returns 0 on success
+ */
+int proc_uint_conv(ulong *u_ptr, uint *k_ptr, int dir,
+ const struct ctl_table *tbl, bool k_ptr_range_check,
+ int (*user_to_kern)(const ulong *u_ptr, uint *k_ptr),
+ int (*kern_to_user)(ulong *u_ptr, const uint *k_ptr))
+{
+ if (SYSCTL_KERN_TO_USER(dir))
+ return kern_to_user(u_ptr, k_ptr);
+
+ if (k_ptr_range_check) {
+ uint tmp_k;
+ int ret;
+
+ if (!tbl)
+ return -EINVAL;
+ ret = user_to_kern(u_ptr, &tmp_k);
+ if (ret)
+ return ret;
+ if ((tbl->extra1 &&
+ *(uint *)tbl->extra1 > tmp_k) ||
+ (tbl->extra2 &&
+ *(uint *)tbl->extra2 < tmp_k))
+ return -ERANGE;
+ WRITE_ONCE(*k_ptr, tmp_k);
+ } else
+ return user_to_kern(u_ptr, k_ptr);
+ return 0;
+}
+
+static int proc_uint_u2k_conv(const ulong *u_ptr, uint *k_ptr)
+{
+ return proc_uint_u2k_conv_uop(u_ptr, k_ptr, NULL);
+}
+
+static int do_proc_uint_conv(ulong *u_ptr, uint *k_ptr, int dir,
+ const struct ctl_table *tbl)
+{
+ return proc_uint_conv(u_ptr, k_ptr, dir, tbl, false,
+ proc_uint_u2k_conv, proc_uint_k2u_conv);
+}
+
+static int do_proc_uint_conv_minmax(ulong *u_ptr, uint *k_ptr, int dir,
+ const struct ctl_table *tbl)
+{
+ return proc_uint_conv(u_ptr, k_ptr, dir, tbl, true,
+ proc_uint_u2k_conv, proc_uint_k2u_conv);
+}
+
static SYSCTL_USER_TO_KERN_INT_CONV(, SYSCTL_CONV_IDENTITY)
static SYSCTL_KERN_TO_USER_INT_CONV(, SYSCTL_CONV_IDENTITY)
@@ -362,22 +466,6 @@ static SYSCTL_INT_CONV_CUSTOM(, sysctl_user_to_kern_int_conv,
static SYSCTL_INT_CONV_CUSTOM(_minmax, sysctl_user_to_kern_int_conv,
sysctl_kern_to_user_int_conv, true)
-
-static SYSCTL_USER_TO_KERN_UINT_CONV(, SYSCTL_CONV_IDENTITY)
-
-int sysctl_kern_to_user_uint_conv(unsigned long *u_ptr,
- const unsigned int *k_ptr)
-{
- unsigned int val = READ_ONCE(*k_ptr);
- *u_ptr = (unsigned long)val;
- return 0;
-}
-
-static SYSCTL_UINT_CONV_CUSTOM(, sysctl_user_to_kern_uint_conv,
- sysctl_kern_to_user_uint_conv, false)
-static SYSCTL_UINT_CONV_CUSTOM(_minmax, sysctl_user_to_kern_uint_conv,
- sysctl_kern_to_user_uint_conv, true)
-
static const char proc_wspace_sep[] = { ' ', '\t', '\n' };
static int do_proc_dointvec(const struct ctl_table *table, int dir,
@@ -576,7 +664,6 @@ int proc_douintvec_conv(const struct ctl_table *table, int dir, void *buffer,
return do_proc_douintvec(table, dir, buffer, lenp, ppos, conv);
}
-
/**
* proc_dobool - read/write a bool
* @table: the sysctl table
@@ -1063,6 +1150,25 @@ int proc_douintvec_conv(const struct ctl_table *table, int write, void *buffer,
return -ENOSYS;
}
+int proc_uint_k2u_conv(ulong *u_ptr, const uint *k_ptr)
+{
+ return -ENOSYS;
+}
+
+int proc_uint_u2k_conv_uop(const ulong *u_ptr, uint *k_ptr,
+ ulong (*u_ptr_op)(const ulong))
+{
+ return -ENOSYS;
+}
+
+int proc_uint_conv(ulong *u_ptr, uint *k_ptr, int dir,
+ const struct ctl_table *tbl, bool k_ptr_range_check,
+ int (*user_to_kern)(const ulong *u_ptr, uint *k_ptr),
+ int (*kern_to_user)(ulong *u_ptr, const uint *k_ptr))
+{
+ return -ENOSYS;
+}
+
int proc_dou8vec_minmax(const struct ctl_table *table, int dir,
void *buffer, size_t *lenp, loff_t *ppos)
{
--
2.50.1
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