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debugfs: use specified mode to possibly mark files read/write only
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In many SoC implementations there are hardware registers can be read or
write only.  This extends the debugfs to enforce the file permissions for
these types of registers by providing a set of fops which are read or
write only.  This assumes that the kernel developer knows more about the
hardware than the user (even root users) -- which is normally true.

Signed-off-by: Robin Getz <rgetz@blackfin.uclinux.org>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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Robin Getz authored and Greg Kroah-Hartman committed Jun 16, 2009
1 parent 156f5a7 commit e4792aa
Showing 1 changed file with 63 additions and 0 deletions.
63 changes: 63 additions & 0 deletions fs/debugfs/file.c
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Original file line number Diff line number Diff line change
Expand Up @@ -67,6 +67,8 @@ static int debugfs_u8_get(void *data, u64 *val)
return 0;
}
DEFINE_SIMPLE_ATTRIBUTE(fops_u8, debugfs_u8_get, debugfs_u8_set, "%llu\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_u8_ro, debugfs_u8_get, NULL, "%llu\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_u8_wo, NULL, debugfs_u8_set, "%llu\n");

/**
* debugfs_create_u8 - create a debugfs file that is used to read and write an unsigned 8-bit value
Expand Down Expand Up @@ -95,6 +97,13 @@ DEFINE_SIMPLE_ATTRIBUTE(fops_u8, debugfs_u8_get, debugfs_u8_set, "%llu\n");
struct dentry *debugfs_create_u8(const char *name, mode_t mode,
struct dentry *parent, u8 *value)
{
/* if there are no write bits set, make read only */
if (!(mode & S_IWUGO))
return debugfs_create_file(name, mode, parent, value, &fops_u8_ro);
/* if there are no read bits set, make write only */
if (!(mode & S_IRUGO))
return debugfs_create_file(name, mode, parent, value, &fops_u8_wo);

return debugfs_create_file(name, mode, parent, value, &fops_u8);
}
EXPORT_SYMBOL_GPL(debugfs_create_u8);
Expand All @@ -110,6 +119,8 @@ static int debugfs_u16_get(void *data, u64 *val)
return 0;
}
DEFINE_SIMPLE_ATTRIBUTE(fops_u16, debugfs_u16_get, debugfs_u16_set, "%llu\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_u16_ro, debugfs_u16_get, NULL, "%llu\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_u16_wo, NULL, debugfs_u16_set, "%llu\n");

/**
* debugfs_create_u16 - create a debugfs file that is used to read and write an unsigned 16-bit value
Expand Down Expand Up @@ -138,6 +149,13 @@ DEFINE_SIMPLE_ATTRIBUTE(fops_u16, debugfs_u16_get, debugfs_u16_set, "%llu\n");
struct dentry *debugfs_create_u16(const char *name, mode_t mode,
struct dentry *parent, u16 *value)
{
/* if there are no write bits set, make read only */
if (!(mode & S_IWUGO))
return debugfs_create_file(name, mode, parent, value, &fops_u16_ro);
/* if there are no read bits set, make write only */
if (!(mode & S_IRUGO))
return debugfs_create_file(name, mode, parent, value, &fops_u16_wo);

return debugfs_create_file(name, mode, parent, value, &fops_u16);
}
EXPORT_SYMBOL_GPL(debugfs_create_u16);
Expand All @@ -153,6 +171,8 @@ static int debugfs_u32_get(void *data, u64 *val)
return 0;
}
DEFINE_SIMPLE_ATTRIBUTE(fops_u32, debugfs_u32_get, debugfs_u32_set, "%llu\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_u32_ro, debugfs_u32_get, NULL, "%llu\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_u32_wo, NULL, debugfs_u32_set, "%llu\n");

/**
* debugfs_create_u32 - create a debugfs file that is used to read and write an unsigned 32-bit value
Expand Down Expand Up @@ -181,6 +201,13 @@ DEFINE_SIMPLE_ATTRIBUTE(fops_u32, debugfs_u32_get, debugfs_u32_set, "%llu\n");
struct dentry *debugfs_create_u32(const char *name, mode_t mode,
struct dentry *parent, u32 *value)
{
/* if there are no write bits set, make read only */
if (!(mode & S_IWUGO))
return debugfs_create_file(name, mode, parent, value, &fops_u32_ro);
/* if there are no read bits set, make write only */
if (!(mode & S_IRUGO))
return debugfs_create_file(name, mode, parent, value, &fops_u32_wo);

return debugfs_create_file(name, mode, parent, value, &fops_u32);
}
EXPORT_SYMBOL_GPL(debugfs_create_u32);
Expand All @@ -197,6 +224,8 @@ static int debugfs_u64_get(void *data, u64 *val)
return 0;
}
DEFINE_SIMPLE_ATTRIBUTE(fops_u64, debugfs_u64_get, debugfs_u64_set, "%llu\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_u64_ro, debugfs_u64_get, NULL, "%llu\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_u64_wo, NULL, debugfs_u64_set, "%llu\n");

/**
* debugfs_create_u64 - create a debugfs file that is used to read and write an unsigned 64-bit value
Expand Down Expand Up @@ -225,15 +254,28 @@ DEFINE_SIMPLE_ATTRIBUTE(fops_u64, debugfs_u64_get, debugfs_u64_set, "%llu\n");
struct dentry *debugfs_create_u64(const char *name, mode_t mode,
struct dentry *parent, u64 *value)
{
/* if there are no write bits set, make read only */
if (!(mode & S_IWUGO))
return debugfs_create_file(name, mode, parent, value, &fops_u64_ro);
/* if there are no read bits set, make write only */
if (!(mode & S_IRUGO))
return debugfs_create_file(name, mode, parent, value, &fops_u64_wo);

return debugfs_create_file(name, mode, parent, value, &fops_u64);
}
EXPORT_SYMBOL_GPL(debugfs_create_u64);

DEFINE_SIMPLE_ATTRIBUTE(fops_x8, debugfs_u8_get, debugfs_u8_set, "0x%02llx\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_x8_ro, debugfs_u8_get, NULL, "0x%02llx\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_x8_wo, NULL, debugfs_u8_set, "0x%02llx\n");

DEFINE_SIMPLE_ATTRIBUTE(fops_x16, debugfs_u16_get, debugfs_u16_set, "0x%04llx\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_x16_ro, debugfs_u16_get, NULL, "0x%04llx\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_x16_wo, NULL, debugfs_u16_set, "0x%04llx\n");

DEFINE_SIMPLE_ATTRIBUTE(fops_x32, debugfs_u32_get, debugfs_u32_set, "0x%08llx\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_x32_ro, debugfs_u32_get, NULL, "0x%08llx\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_x32_wo, NULL, debugfs_u32_set, "0x%08llx\n");

/*
* debugfs_create_x{8,16,32} - create a debugfs file that is used to read and write an unsigned {8,16,32}-bit value
Expand All @@ -256,6 +298,13 @@ DEFINE_SIMPLE_ATTRIBUTE(fops_x32, debugfs_u32_get, debugfs_u32_set, "0x%08llx\n"
struct dentry *debugfs_create_x8(const char *name, mode_t mode,
struct dentry *parent, u8 *value)
{
/* if there are no write bits set, make read only */
if (!(mode & S_IWUGO))
return debugfs_create_file(name, mode, parent, value, &fops_x8_ro);
/* if there are no read bits set, make write only */
if (!(mode & S_IRUGO))
return debugfs_create_file(name, mode, parent, value, &fops_x8_wo);

return debugfs_create_file(name, mode, parent, value, &fops_x8);
}
EXPORT_SYMBOL_GPL(debugfs_create_x8);
Expand All @@ -273,6 +322,13 @@ EXPORT_SYMBOL_GPL(debugfs_create_x8);
struct dentry *debugfs_create_x16(const char *name, mode_t mode,
struct dentry *parent, u16 *value)
{
/* if there are no write bits set, make read only */
if (!(mode & S_IWUGO))
return debugfs_create_file(name, mode, parent, value, &fops_x16_ro);
/* if there are no read bits set, make write only */
if (!(mode & S_IRUGO))
return debugfs_create_file(name, mode, parent, value, &fops_x16_wo);

return debugfs_create_file(name, mode, parent, value, &fops_x16);
}
EXPORT_SYMBOL_GPL(debugfs_create_x16);
Expand All @@ -290,6 +346,13 @@ EXPORT_SYMBOL_GPL(debugfs_create_x16);
struct dentry *debugfs_create_x32(const char *name, mode_t mode,
struct dentry *parent, u32 *value)
{
/* if there are no write bits set, make read only */
if (!(mode & S_IWUGO))
return debugfs_create_file(name, mode, parent, value, &fops_x32_ro);
/* if there are no read bits set, make write only */
if (!(mode & S_IRUGO))
return debugfs_create_file(name, mode, parent, value, &fops_x32_wo);

return debugfs_create_file(name, mode, parent, value, &fops_x32);
}
EXPORT_SYMBOL_GPL(debugfs_create_x32);
Expand Down

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