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NAME | DESCRIPTION | SEE ALSO | COLOPHON |
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proc_pid_attr(5) File Formats Manual proc_pid_attr(5)
/proc/pid/attr/ - security-related attributes
/proc/pid/attr/
The files in this directory provide an API for security
modules. The contents of this directory are files that
can be read and written in order to set security-related
attributes. This directory was added to support SELinux,
but the intention was that the API be general enough to
support other security modules. For the purpose of
explanation, examples of how SELinux uses these files are
provided below.
This directory is present only if the kernel was
configured with CONFIG_SECURITY.
/proc/pid/attr/current (since Linux 2.6.0)
The contents of this file represent the current security
attributes of the process.
In SELinux, this file is used to get the security context
of a process. Prior to Linux 2.6.11, this file could not
be used to set the security context (a write was always
denied), since SELinux limited process security
transitions to execve(2) (see the description of
/proc/pid/attr/exec, below). Since Linux 2.6.11, SELinux
lifted this restriction and began supporting "set"
operations via writes to this node if authorized by
policy, although use of this operation is only suitable
for applications that are trusted to maintain any desired
separation between the old and new security contexts.
Prior to Linux 2.6.28, SELinux did not allow threads
within a multithreaded process to set their security
context via this node as it would yield an inconsistency
among the security contexts of the threads sharing the
same memory space. Since Linux 2.6.28, SELinux lifted
this restriction and began supporting "set" operations for
threads within a multithreaded process if the new security
context is bounded by the old security context, where the
bounded relation is defined in policy and guarantees that
the new security context has a subset of the permissions
of the old security context.
Other security modules may choose to support "set"
operations via writes to this node.
/proc/pid/attr/exec (since Linux 2.6.0)
This file represents the attributes to assign to the
process upon a subsequent execve(2).
In SELinux, this is needed to support role/domain
transitions, and execve(2) is the preferred point to make
such transitions because it offers better control over the
initialization of the process in the new security label
and the inheritance of state. In SELinux, this attribute
is reset on execve(2) so that the new program reverts to
the default behavior for any execve(2) calls that it may
make. In SELinux, a process can set only its own
/proc/pid/attr/exec attribute.
/proc/pid/attr/fscreate (since Linux 2.6.0)
This file represents the attributes to assign to files
created by subsequent calls to open(2), mkdir(2),
symlink(2), and mknod(2)
SELinux employs this file to support creation of a file
(using the aforementioned system calls) in a secure state,
so that there is no risk of inappropriate access being
obtained between the time of creation and the time that
attributes are set. In SELinux, this attribute is reset
on execve(2), so that the new program reverts to the
default behavior for any file creation calls it may make,
but the attribute will persist across multiple file
creation calls within a program unless it is explicitly
reset. In SELinux, a process can set only its own
/proc/pid/attr/fscreate attribute.
/proc/pid/attr/keycreate (since Linux 2.6.18)
If a process writes a security context into this file, all
subsequently created keys (add_key(2)) will be labeled
with this context. For further information, see the
kernel source file Documentation/security/keys/core.rst
(or file Documentation/security/keys.txt between Linux 3.0
and Linux 4.13, or Documentation/keys.txt before Linux
3.0).
/proc/pid/attr/prev (since Linux 2.6.0)
This file contains the security context of the process
before the last execve(2); that is, the previous value of
/proc/pid/attr/current.
/proc/pid/attr/socketcreate (since Linux 2.6.18)
If a process writes a security context into this file, all
subsequently created sockets will be labeled with this
context.
proc(5)
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Linux man-pages 6.9.1 2024-05-02 proc_pid_attr(5)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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