| Message ID | 20200210150519.538333-9-gladkov.alexey@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | proc: modernize proc to support multiple private instances | expand |
On Monday, February 10, 2020 3:05 PM, Alexey Gladkov <gladkov.alexey@gmail.com> wrote: > If "hidepid=4" mount option is set then do not instantiate pids that > we can not ptrace. "hidepid=4" means that procfs should only contain > pids that the caller can ptrace. > > Cc: Kees Cook keescook@chromium.org > Cc: Andy Lutomirski luto@kernel.org > Signed-off-by: Djalal Harouni tixxdz@gmail.com > Signed-off-by: Alexey Gladkov gladkov.alexey@gmail.com > > fs/proc/base.c | 15 +++++++++++++++ > fs/proc/root.c | 14 +++++++++++--- > include/linux/proc_fs.h | 1 + > 3 files changed, 27 insertions(+), 3 deletions(-) > > diff --git a/fs/proc/base.c b/fs/proc/base.c > index 24b7c620ded3..49937d54e745 100644 > --- a/fs/proc/base.c > +++ b/fs/proc/base.c > @@ -699,6 +699,14 @@ static bool has_pid_permissions(struct proc_fs_info *fs_info, > struct task_struct *task, > int hide_pid_min) > { > > - /* > - - If 'hidpid' mount option is set force a ptrace check, > - - we indicate that we are using a filesystem syscall > - - by passing PTRACE_MODE_READ_FSCREDS > - */ > - if (proc_fs_hide_pid(fs_info) == HIDEPID_NOT_PTRACABLE) > - return ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS); > > > - if (proc_fs_hide_pid(fs_info) < hide_pid_min) > return true; > if (in_group_p(proc_fs_pid_gid(fs_info))) > @@ -3271,7 +3279,14 @@ struct dentry *proc_pid_lookup(struct dentry *dentry, unsigned int flags) > if (!task) > goto out; > > - /* Limit procfs to only ptracable tasks */ > - if (proc_fs_hide_pid(fs_info) == HIDEPID_NOT_PTRACABLE) { > - if (!has_pid_permissions(fs_info, task, HIDEPID_NO_ACCESS)) > > > - goto out_put_task; > > > - } > - result = proc_pid_instantiate(dentry, task, NULL); > +out_put_task: > put_task_struct(task); > out: > return result; > diff --git a/fs/proc/root.c b/fs/proc/root.c > index e2bb015da1a8..5e27bb31f125 100644 > --- a/fs/proc/root.c > +++ b/fs/proc/root.c > @@ -52,6 +52,15 @@ static const struct fs_parameter_description proc_fs_parameters = { > .specs = proc_param_specs, > }; > > +static inline int > +valid_hidepid(unsigned int value) > +{ > > - return (value == HIDEPID_OFF || > - value == HIDEPID_NO_ACCESS || > > > - value == HIDEPID_INVISIBLE || > > > - value == HIDEPID_NOT_PTRACABLE); > > > > +} > + > static int proc_parse_param(struct fs_context *fc, struct fs_parameter *param) > { > struct proc_fs_context *ctx = fc->fs_private; > @@ -68,10 +77,9 @@ static int proc_parse_param(struct fs_context *fc, struct fs_parameter *param) > break; > > case Opt_hidepid: > > - if (!valid_hidepid(result.uint_32)) > > > - return invalf(fc, "proc: unknown value of hidepid.\\n"); > ctx->hidepid = result.uint_32; > > > > - if (ctx->hidepid < HIDEPID_OFF || > > > - ctx->hidepid > HIDEPID_INVISIBLE) > > > - return invalf(fc, "proc: hidepid value must be between 0 and 2.\\n"); > break; > > > > default: > diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h > index f307940f8311..6822548405a7 100644 > --- a/include/linux/proc_fs.h > +++ b/include/linux/proc_fs.h > @@ -17,6 +17,7 @@ enum { > HIDEPID_OFF = 0, > HIDEPID_NO_ACCESS = 1, > HIDEPID_INVISIBLE = 2, > > - HIDEPID_NOT_PTRACABLE = 4, /* Limit pids to only ptracable pids */ Is there a reason new option is "4" instead of "3"? The order 1..2..4 may be confusing for people. Jordan
On Mon, Feb 10, 2020 at 04:29:31PM +0000, Jordan Glover wrote: > On Monday, February 10, 2020 3:05 PM, Alexey Gladkov <gladkov.alexey@gmail.com> wrote: > > > If "hidepid=4" mount option is set then do not instantiate pids that > > we can not ptrace. "hidepid=4" means that procfs should only contain > > pids that the caller can ptrace. > > > > Cc: Kees Cook keescook@chromium.org > > Cc: Andy Lutomirski luto@kernel.org > > Signed-off-by: Djalal Harouni tixxdz@gmail.com > > Signed-off-by: Alexey Gladkov gladkov.alexey@gmail.com > > > > fs/proc/base.c | 15 +++++++++++++++ > > fs/proc/root.c | 14 +++++++++++--- > > include/linux/proc_fs.h | 1 + > > 3 files changed, 27 insertions(+), 3 deletions(-) > > > > diff --git a/fs/proc/base.c b/fs/proc/base.c > > index 24b7c620ded3..49937d54e745 100644 > > --- a/fs/proc/base.c > > +++ b/fs/proc/base.c > > @@ -699,6 +699,14 @@ static bool has_pid_permissions(struct proc_fs_info *fs_info, > > struct task_struct *task, > > int hide_pid_min) > > { > > > > - /* > > - - If 'hidpid' mount option is set force a ptrace check, > > - - we indicate that we are using a filesystem syscall > > - - by passing PTRACE_MODE_READ_FSCREDS > > - */ > > - if (proc_fs_hide_pid(fs_info) == HIDEPID_NOT_PTRACABLE) > > - return ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS); > > > > > > - if (proc_fs_hide_pid(fs_info) < hide_pid_min) > > return true; > > if (in_group_p(proc_fs_pid_gid(fs_info))) > > @@ -3271,7 +3279,14 @@ struct dentry *proc_pid_lookup(struct dentry *dentry, unsigned int flags) > > if (!task) > > goto out; > > > > - /* Limit procfs to only ptracable tasks */ > > - if (proc_fs_hide_pid(fs_info) == HIDEPID_NOT_PTRACABLE) { > > - if (!has_pid_permissions(fs_info, task, HIDEPID_NO_ACCESS)) > > > > > > - goto out_put_task; > > > > > > - } > > - result = proc_pid_instantiate(dentry, task, NULL); > > +out_put_task: > > put_task_struct(task); > > out: > > return result; > > diff --git a/fs/proc/root.c b/fs/proc/root.c > > index e2bb015da1a8..5e27bb31f125 100644 > > --- a/fs/proc/root.c > > +++ b/fs/proc/root.c > > @@ -52,6 +52,15 @@ static const struct fs_parameter_description proc_fs_parameters = { > > .specs = proc_param_specs, > > }; > > > > +static inline int > > +valid_hidepid(unsigned int value) > > +{ > > > > - return (value == HIDEPID_OFF || > > - value == HIDEPID_NO_ACCESS || > > > > > > - value == HIDEPID_INVISIBLE || > > > > > > - value == HIDEPID_NOT_PTRACABLE); > > > > > > > > +} > > + > > static int proc_parse_param(struct fs_context *fc, struct fs_parameter *param) > > { > > struct proc_fs_context *ctx = fc->fs_private; > > @@ -68,10 +77,9 @@ static int proc_parse_param(struct fs_context *fc, struct fs_parameter *param) > > break; > > > > case Opt_hidepid: > > > > - if (!valid_hidepid(result.uint_32)) > > > > > > - return invalf(fc, "proc: unknown value of hidepid.\\n"); > > ctx->hidepid = result.uint_32; > > > > > > > > - if (ctx->hidepid < HIDEPID_OFF || > > > > > > - ctx->hidepid > HIDEPID_INVISIBLE) > > > > > > - return invalf(fc, "proc: hidepid value must be between 0 and 2.\\n"); > > break; > > > > > > > > default: > > diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h > > index f307940f8311..6822548405a7 100644 > > --- a/include/linux/proc_fs.h > > +++ b/include/linux/proc_fs.h > > @@ -17,6 +17,7 @@ enum { > > HIDEPID_OFF = 0, > > HIDEPID_NO_ACCESS = 1, > > HIDEPID_INVISIBLE = 2, > > > > - HIDEPID_NOT_PTRACABLE = 4, /* Limit pids to only ptracable pids */ > > Is there a reason new option is "4" instead of "3"? The order 1..2..4 may be > confusing for people. This is just mask. For now hidepid values are mutually exclusive, but since it moved to uapi, I thought it would be good if there was an opportunity to combine values.
diff --git a/fs/proc/base.c b/fs/proc/base.c index 24b7c620ded3..49937d54e745 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -699,6 +699,14 @@ static bool has_pid_permissions(struct proc_fs_info *fs_info, struct task_struct *task, int hide_pid_min) { + /* + * If 'hidpid' mount option is set force a ptrace check, + * we indicate that we are using a filesystem syscall + * by passing PTRACE_MODE_READ_FSCREDS + */ + if (proc_fs_hide_pid(fs_info) == HIDEPID_NOT_PTRACABLE) + return ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS); + if (proc_fs_hide_pid(fs_info) < hide_pid_min) return true; if (in_group_p(proc_fs_pid_gid(fs_info))) @@ -3271,7 +3279,14 @@ struct dentry *proc_pid_lookup(struct dentry *dentry, unsigned int flags) if (!task) goto out; + /* Limit procfs to only ptracable tasks */ + if (proc_fs_hide_pid(fs_info) == HIDEPID_NOT_PTRACABLE) { + if (!has_pid_permissions(fs_info, task, HIDEPID_NO_ACCESS)) + goto out_put_task; + } + result = proc_pid_instantiate(dentry, task, NULL); +out_put_task: put_task_struct(task); out: return result; diff --git a/fs/proc/root.c b/fs/proc/root.c index e2bb015da1a8..5e27bb31f125 100644 --- a/fs/proc/root.c +++ b/fs/proc/root.c @@ -52,6 +52,15 @@ static const struct fs_parameter_description proc_fs_parameters = { .specs = proc_param_specs, }; +static inline int +valid_hidepid(unsigned int value) +{ + return (value == HIDEPID_OFF || + value == HIDEPID_NO_ACCESS || + value == HIDEPID_INVISIBLE || + value == HIDEPID_NOT_PTRACABLE); +} + static int proc_parse_param(struct fs_context *fc, struct fs_parameter *param) { struct proc_fs_context *ctx = fc->fs_private; @@ -68,10 +77,9 @@ static int proc_parse_param(struct fs_context *fc, struct fs_parameter *param) break; case Opt_hidepid: + if (!valid_hidepid(result.uint_32)) + return invalf(fc, "proc: unknown value of hidepid.\n"); ctx->hidepid = result.uint_32; - if (ctx->hidepid < HIDEPID_OFF || - ctx->hidepid > HIDEPID_INVISIBLE) - return invalf(fc, "proc: hidepid value must be between 0 and 2.\n"); break; default: diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h index f307940f8311..6822548405a7 100644 --- a/include/linux/proc_fs.h +++ b/include/linux/proc_fs.h @@ -17,6 +17,7 @@ enum { HIDEPID_OFF = 0, HIDEPID_NO_ACCESS = 1, HIDEPID_INVISIBLE = 2, + HIDEPID_NOT_PTRACABLE = 4, /* Limit pids to only ptracable pids */ }; struct proc_fs_info {