| Message ID | 20230613004054.3539554-1-azeemshaikh38@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | SUNRPC: Replace strlcpy with strscpy | expand |
> On Jun 12, 2023, at 8:40 PM, Azeem Shaikh <azeemshaikh38@gmail.com> wrote: > > strlcpy() reads the entire source buffer first. > This read may exceed the destination size limit. > This is both inefficient and can lead to linear read > overflows if a source string is not NUL-terminated [1]. > In an effort to remove strlcpy() completely [2], replace > strlcpy() here with strscpy(). Using sprintf() seems cleaner to me: it would get rid of the undocumented naked integer. Would that work for you? > Direct replacement is safe here since the getter in kernel_params_ops > handles -errorno return [3]. s/errorno/errno/ > [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy > [2] https://github.com/KSPP/linux/issues/89 > [3] https://elixir.bootlin.com/linux/v6.4-rc6/source/include/linux/moduleparam.h#L52 > > Signed-off-by: Azeem Shaikh <azeemshaikh38@gmail.com> > --- > net/sunrpc/svc.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c > index e6d4cec61e47..e5f379c4fdb3 100644 > --- a/net/sunrpc/svc.c > +++ b/net/sunrpc/svc.c > @@ -109,13 +109,13 @@ param_get_pool_mode(char *buf, const struct kernel_param *kp) > switch (*ip) > { > case SVC_POOL_AUTO: > - return strlcpy(buf, "auto\n", 20); > + return strscpy(buf, "auto\n", 20); > case SVC_POOL_GLOBAL: > - return strlcpy(buf, "global\n", 20); > + return strscpy(buf, "global\n", 20); > case SVC_POOL_PERCPU: > - return strlcpy(buf, "percpu\n", 20); > + return strscpy(buf, "percpu\n", 20); > case SVC_POOL_PERNODE: > - return strlcpy(buf, "pernode\n", 20); > + return strscpy(buf, "pernode\n", 20); > default: > return sprintf(buf, "%d\n", *ip); > } > -- > 2.41.0.162.gfafddb0af9-goog > > -- Chuck Lever
On Tue, Jun 13, 2023 at 02:18:06PM +0000, Chuck Lever III wrote: > > > > On Jun 12, 2023, at 8:40 PM, Azeem Shaikh <azeemshaikh38@gmail.com> wrote: > > > > strlcpy() reads the entire source buffer first. > > This read may exceed the destination size limit. > > This is both inefficient and can lead to linear read > > overflows if a source string is not NUL-terminated [1]. > > In an effort to remove strlcpy() completely [2], replace > > strlcpy() here with strscpy(). > > Using sprintf() seems cleaner to me: it would get rid of > the undocumented naked integer. Would that work for you? This is changing the "get" routine for reporting module parameters out of /sys. I think the right choice here is sysfs_emit(), as it performs the size tracking correctly. (Even the "default" sprintf() call should be replaced too, IMO.) > > > > Direct replacement is safe here since the getter in kernel_params_ops > > handles -errorno return [3]. > > s/errorno/errno/ > > > > [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy > > [2] https://github.com/KSPP/linux/issues/89 > > [3] https://elixir.bootlin.com/linux/v6.4-rc6/source/include/linux/moduleparam.h#L52 > > > > Signed-off-by: Azeem Shaikh <azeemshaikh38@gmail.com> > > --- > > net/sunrpc/svc.c | 8 ++++---- > > 1 file changed, 4 insertions(+), 4 deletions(-) > > > > diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c > > index e6d4cec61e47..e5f379c4fdb3 100644 > > --- a/net/sunrpc/svc.c > > +++ b/net/sunrpc/svc.c > > @@ -109,13 +109,13 @@ param_get_pool_mode(char *buf, const struct kernel_param *kp) > > switch (*ip) > > { > > case SVC_POOL_AUTO: > > - return strlcpy(buf, "auto\n", 20); > > + return strscpy(buf, "auto\n", 20); e.g. return sysfs_emit(buf, "auto\n"); ... > > case SVC_POOL_GLOBAL: > > - return strlcpy(buf, "global\n", 20); > > + return strscpy(buf, "global\n", 20); > > case SVC_POOL_PERCPU: > > - return strlcpy(buf, "percpu\n", 20); > > + return strscpy(buf, "percpu\n", 20); > > case SVC_POOL_PERNODE: > > - return strlcpy(buf, "pernode\n", 20); > > + return strscpy(buf, "pernode\n", 20); > > default: > > return sprintf(buf, "%d\n", *ip); and: return sysfs_emit(buf, "%d\n", *ip); -Kees
> On Jun 13, 2023, at 3:42 PM, Kees Cook <keescook@chromium.org> wrote: > > On Tue, Jun 13, 2023 at 02:18:06PM +0000, Chuck Lever III wrote: >> >> >>> On Jun 12, 2023, at 8:40 PM, Azeem Shaikh <azeemshaikh38@gmail.com> wrote: >>> >>> strlcpy() reads the entire source buffer first. >>> This read may exceed the destination size limit. >>> This is both inefficient and can lead to linear read >>> overflows if a source string is not NUL-terminated [1]. >>> In an effort to remove strlcpy() completely [2], replace >>> strlcpy() here with strscpy(). >> >> Using sprintf() seems cleaner to me: it would get rid of >> the undocumented naked integer. Would that work for you? > > This is changing the "get" routine for reporting module parameters out > of /sys. I think the right choice here is sysfs_emit(), as it performs > the size tracking correctly. (Even the "default" sprintf() call should > be replaced too, IMO.) Agreed, that's even better. >>> Direct replacement is safe here since the getter in kernel_params_ops >>> handles -errorno return [3]. >> >> s/errorno/errno/ >> >> >>> [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy >>> [2] https://github.com/KSPP/linux/issues/89 >>> [3] https://elixir.bootlin.com/linux/v6.4-rc6/source/include/linux/moduleparam.h#L52 >>> >>> Signed-off-by: Azeem Shaikh <azeemshaikh38@gmail.com> >>> --- >>> net/sunrpc/svc.c | 8 ++++---- >>> 1 file changed, 4 insertions(+), 4 deletions(-) >>> >>> diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c >>> index e6d4cec61e47..e5f379c4fdb3 100644 >>> --- a/net/sunrpc/svc.c >>> +++ b/net/sunrpc/svc.c >>> @@ -109,13 +109,13 @@ param_get_pool_mode(char *buf, const struct kernel_param *kp) >>> switch (*ip) >>> { >>> case SVC_POOL_AUTO: >>> - return strlcpy(buf, "auto\n", 20); >>> + return strscpy(buf, "auto\n", 20); > > e.g. > return sysfs_emit(buf, "auto\n"); > ... > >>> case SVC_POOL_GLOBAL: >>> - return strlcpy(buf, "global\n", 20); >>> + return strscpy(buf, "global\n", 20); >>> case SVC_POOL_PERCPU: >>> - return strlcpy(buf, "percpu\n", 20); >>> + return strscpy(buf, "percpu\n", 20); >>> case SVC_POOL_PERNODE: >>> - return strlcpy(buf, "pernode\n", 20); >>> + return strscpy(buf, "pernode\n", 20); >>> default: >>> return sprintf(buf, "%d\n", *ip); > > and: > > return sysfs_emit(buf, "%d\n", *ip); > > > -Kees > > -- > Kees Cook -- Chuck Lever
On Tue, Jun 13, 2023 at 3:43 PM Chuck Lever III <chuck.lever@oracle.com> wrote: > > > On Jun 13, 2023, at 3:42 PM, Kees Cook <keescook@chromium.org> wrote: > > > > On Tue, Jun 13, 2023 at 02:18:06PM +0000, Chuck Lever III wrote: > >> > >> > >>> On Jun 12, 2023, at 8:40 PM, Azeem Shaikh <azeemshaikh38@gmail.com> wrote: > >>> > >>> strlcpy() reads the entire source buffer first. > >>> This read may exceed the destination size limit. > >>> This is both inefficient and can lead to linear read > >>> overflows if a source string is not NUL-terminated [1]. > >>> In an effort to remove strlcpy() completely [2], replace > >>> strlcpy() here with strscpy(). > >> > >> Using sprintf() seems cleaner to me: it would get rid of > >> the undocumented naked integer. Would that work for you? > > > > This is changing the "get" routine for reporting module parameters out > > of /sys. I think the right choice here is sysfs_emit(), as it performs > > the size tracking correctly. (Even the "default" sprintf() call should > > be replaced too, IMO.) > > Agreed, that's even better. > Thanks folks. Will send over a v2 which replaces strlcpy with sysfs_emit.
diff --git a/net/sunrpc/svc.c b/net/sunrpc/svc.c index e6d4cec61e47..e5f379c4fdb3 100644 --- a/net/sunrpc/svc.c +++ b/net/sunrpc/svc.c @@ -109,13 +109,13 @@ param_get_pool_mode(char *buf, const struct kernel_param *kp) switch (*ip) { case SVC_POOL_AUTO: - return strlcpy(buf, "auto\n", 20); + return strscpy(buf, "auto\n", 20); case SVC_POOL_GLOBAL: - return strlcpy(buf, "global\n", 20); + return strscpy(buf, "global\n", 20); case SVC_POOL_PERCPU: - return strlcpy(buf, "percpu\n", 20); + return strscpy(buf, "percpu\n", 20); case SVC_POOL_PERNODE: - return strlcpy(buf, "pernode\n", 20); + return strscpy(buf, "pernode\n", 20); default: return sprintf(buf, "%d\n", *ip); }
strlcpy() reads the entire source buffer first. This read may exceed the destination size limit. This is both inefficient and can lead to linear read overflows if a source string is not NUL-terminated [1]. In an effort to remove strlcpy() completely [2], replace strlcpy() here with strscpy(). Direct replacement is safe here since the getter in kernel_params_ops handles -errorno return [3]. [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#strlcpy [2] https://github.com/KSPP/linux/issues/89 [3] https://elixir.bootlin.com/linux/v6.4-rc6/source/include/linux/moduleparam.h#L52 Signed-off-by: Azeem Shaikh <azeemshaikh38@gmail.com> --- net/sunrpc/svc.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)