keyctl_update_key

Name:Update a key's data payload from the given data.* The key must grant the caller Write permission and the key type must support* updating for this to work. A negative key can be positively instantiated* with this call.* If successful, 0 will be returned

Proto:long keyctl_update_key(key_serial_t id, const void __user *_payload, size_t plen)

Type:long

Parameter:

Type	Parameter	Name
key_serial_t	id
const void __user *	_payload
size_t	plen

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If plen > PAGE_SIZE Then Go to error

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payload = NULL

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If plen Then

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payload = Allocation memory

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If Not payload Then Go to error

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If copy_from_user(payload, _payload, plen) != 0 Then Go to error2

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key_ref = Look up a key ID given us by userspace with a given permissions mask to get* the key it refers to.* Flags can be passed to request that special keyrings be created if referred* to directly, to permit partially constructed keys to be found and to skip

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If IS_ERR(key_ref) Then

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ret = PTR_ERR(key_ref)

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Go to error2

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ret = key_update - Update a key's contents.*@key_ref: The pointer (plus possession flag) to the key.*@payload: The data to be used to update the key.*@plen: The length of @payload.* Attempt to update the contents of a key with the given payload data. The

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key_ref_put(key_ref)

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kzfree - like kfree but zero memory*@p: object to free memory of* The memory of the object @p points to is zeroed before freed.* If @p is %NULL, kzfree() does nothing.* Note: this function zeroes the whole allocated buffer which can be a good

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error :

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Return ret

**Caller**
Name	Describe
SYSCALL_DEFINE5	The key control system call
COMPAT_SYSCALL_DEFINE5	The key control system call, 32-bit compatibility version for 64-bit archs

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