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Diffstat (limited to 'Documentation/filesystems/proc.rst')
| -rw-r--r-- | Documentation/filesystems/proc.rst | 52 |
1 files changed, 26 insertions, 26 deletions
diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst index 360486c7a992..e2ecf248feb5 100644 --- a/Documentation/filesystems/proc.rst +++ b/Documentation/filesystems/proc.rst @@ -2147,28 +2147,28 @@ The following mount options are supported: subset= Show only the specified subset of procfs. ========= ======================================================== -hidepid=0 means classic mode - everybody may access all /proc/<pid>/ directories -(default). - -hidepid=1 means users may not access any /proc/<pid>/ directories but their -own. Sensitive files like cmdline, sched*, status are now protected against -other users. This makes it impossible to learn whether any user runs -specific program (given the program doesn't reveal itself by its behaviour). -As an additional bonus, as /proc/<pid>/cmdline is unaccessible for other users, -poorly written programs passing sensitive information via program arguments are -now protected against local eavesdroppers. - -hidepid=2 means hidepid=1 plus all /proc/<pid>/ will be fully invisible to other -users. It doesn't mean that it hides a fact whether a process with a specific -pid value exists (it can be learned by other means, e.g. by "kill -0 $PID"), -but it hides process' uid and gid, which may be learned by stat()'ing -/proc/<pid>/ otherwise. It greatly complicates an intruder's task of gathering -information about running processes, whether some daemon runs with elevated -privileges, whether other user runs some sensitive program, whether other users -run any program at all, etc. - -hidepid=4 means that procfs should only contain /proc/<pid>/ directories -that the caller can ptrace. +hidepid=off or hidepid=0 means classic mode - everybody may access all +/proc/<pid>/ directories (default). + +hidepid=noaccess or hidepid=1 means users may not access any /proc/<pid>/ +directories but their own. Sensitive files like cmdline, sched*, status are now +protected against other users. This makes it impossible to learn whether any +user runs specific program (given the program doesn't reveal itself by its +behaviour). As an additional bonus, as /proc/<pid>/cmdline is unaccessible for +other users, poorly written programs passing sensitive information via program +arguments are now protected against local eavesdroppers. + +hidepid=invisible or hidepid=2 means hidepid=1 plus all /proc/<pid>/ will be +fully invisible to other users. It doesn't mean that it hides a fact whether a +process with a specific pid value exists (it can be learned by other means, e.g. +by "kill -0 $PID"), but it hides process' uid and gid, which may be learned by +stat()'ing /proc/<pid>/ otherwise. It greatly complicates an intruder's task of +gathering information about running processes, whether some daemon runs with +elevated privileges, whether other user runs some sensitive program, whether +other users run any program at all, etc. + +hidepid=ptraceable or hidepid=4 means that procfs should only contain +/proc/<pid>/ directories that the caller can ptrace. gid= defines a group authorized to learn processes information otherwise prohibited by hidepid=. If you use some daemon like identd which needs to learn @@ -2216,8 +2216,8 @@ creates a new procfs instance. Mount options affect own procfs instance. It means that it became possible to have several procfs instances displaying tasks with different filtering options in one pid namespace. -# mount -o hidepid=2 -t proc proc /proc -# mount -o hidepid=1 -t proc proc /tmp/proc +# mount -o hidepid=invisible -t proc proc /proc +# mount -o hidepid=noaccess -t proc proc /tmp/proc # grep ^proc /proc/mounts -proc /proc proc rw,relatime,hidepid=2 0 0 -proc /tmp/proc proc rw,relatime,hidepid=1 0 0 +proc /proc proc rw,relatime,hidepid=invisible 0 0 +proc /tmp/proc proc rw,relatime,hidepid=noaccess 0 0 |