version 1, including all changes.
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SETFSUID |
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!!!SETFSUID |
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NAME |
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SYNOPSIS |
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DESCRIPTION |
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RETURN VALUE |
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CONFORMING TO |
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BUGS |
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NOTE |
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SEE ALSO |
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---- |
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!!NAME |
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setfsuid - set user identity used for file system checks |
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!!SYNOPSIS |
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__#include __ /* glibc uses |
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__ |
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__int setfsuid(uid_t__ ''fsuid''__);__ |
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!!DESCRIPTION |
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__setfsuid__ sets the user ID that the Linux kernel uses |
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to check for all accesses to the file system. Normally, the |
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value of ''fsuid'' will shadow the value of the effective |
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user ID. In fact, whenever the effective user ID is changed, |
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''fsuid'' will also be changed to new value of effective |
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user ID. |
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An explict call to __setfsuid__ is usually only used by |
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programs such as the Linux NFS server that need to change |
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what user ID is used for file access without a corresponding |
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change in the real and effective user IDs. A change in the |
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normal user IDs for a program such as the NFS server is a |
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security hole that can expose it to unwanted signals from |
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other user IDs. |
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__setfsuid__ will only succeed if the caller is the |
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superuser or if ''fsuid'' matches either the real user |
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ID, effective user ID, saved set-user-ID, or the current |
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value of ''fsuid''. |
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!!RETURN VALUE |
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On success, the previous value of ''fsuid'' is returned. |
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On error, the current value of ''fsuid'' is |
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returned. |
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!!CONFORMING TO |
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__setfsuid__ is Linux specific and should not be used in |
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programs intended to be portable. |
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!!BUGS |
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No error messages of any kind are returned to the caller. At |
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the very least, __EPERM__ should be returned when the |
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call fails. |
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!!NOTE |
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When glibc determines that the argument is not a valid uid, |
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it will return -1 and set ''errno'' to EINVAL without |
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attempting the system call. |
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!!SEE ALSO |
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setfsgid(2) |
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---- |
