* [PATCH v3] seccomp: Add find_notification helper @ 2020-06-01 11:25 Sargun Dhillon 2020-06-01 18:26 ` Kees Cook 2020-06-17 20:08 ` Nathan Chancellor 0 siblings, 2 replies; 6+ messages in thread From: Sargun Dhillon @ 2020-06-01 11:25 UTC (permalink / raw) To: containers, keescook, linux-api, linux-kernel Cc: Sargun Dhillon, viro, christian.brauner, cyphar, jannh, jeffv, palmer, rsesek, tycho, Matt Denton, Kees Cook This adds a helper which can iterate through a seccomp_filter to find a notification matching an ID. It removes several replicated chunks of code. Signed-off-by: Sargun Dhillon <sargun@sargun.me> Acked-by: Christian Brauner <christian.brauner@ubuntu.com> Reviewed-by: Tycho Andersen <tycho@tycho.ws> Cc: Matt Denton <mpdenton@google.com> Cc: Kees Cook <keescook@google.com>, Cc: Jann Horn <jannh@google.com>, Cc: Robert Sesek <rsesek@google.com>, Cc: Chris Palmer <palmer@google.com> Cc: Christian Brauner <christian.brauner@ubuntu.com> Cc: Tycho Andersen <tycho@tycho.ws> --- kernel/seccomp.c | 55 ++++++++++++++++++++++++------------------------ 1 file changed, 28 insertions(+), 27 deletions(-) diff --git a/kernel/seccomp.c b/kernel/seccomp.c index 55a6184f5990..cc6b47173a95 100644 --- a/kernel/seccomp.c +++ b/kernel/seccomp.c @@ -41,6 +41,7 @@ #include <linux/tracehook.h> #include <linux/uaccess.h> #include <linux/anon_inodes.h> +#include <linux/lockdep.h> enum notify_state { SECCOMP_NOTIFY_INIT, @@ -1021,10 +1022,27 @@ static int seccomp_notify_release(struct inode *inode, struct file *file) return 0; } +/* must be called with notif_lock held */ +static inline struct seccomp_knotif * +find_notification(struct seccomp_filter *filter, u64 id) +{ + struct seccomp_knotif *cur; + + lockdep_assert_held(&filter->notify_lock); + + list_for_each_entry(cur, &filter->notif->notifications, list) { + if (cur->id == id) + return cur; + } + + return NULL; +} + + static long seccomp_notify_recv(struct seccomp_filter *filter, void __user *buf) { - struct seccomp_knotif *knotif = NULL, *cur; + struct seccomp_knotif *knotif, *cur; struct seccomp_notif unotif; ssize_t ret; @@ -1078,15 +1096,8 @@ static long seccomp_notify_recv(struct seccomp_filter *filter, * may have died when we released the lock, so we need to make * sure it's still around. */ - knotif = NULL; mutex_lock(&filter->notify_lock); - list_for_each_entry(cur, &filter->notif->notifications, list) { - if (cur->id == unotif.id) { - knotif = cur; - break; - } - } - + knotif = find_notification(filter, unotif.id); if (knotif) { knotif->state = SECCOMP_NOTIFY_INIT; up(&filter->notif->request); @@ -1101,7 +1112,7 @@ static long seccomp_notify_send(struct seccomp_filter *filter, void __user *buf) { struct seccomp_notif_resp resp = {}; - struct seccomp_knotif *knotif = NULL, *cur; + struct seccomp_knotif *knotif; long ret; if (copy_from_user(&resp, buf, sizeof(resp))) @@ -1118,13 +1129,7 @@ static long seccomp_notify_send(struct seccomp_filter *filter, if (ret < 0) return ret; - list_for_each_entry(cur, &filter->notif->notifications, list) { - if (cur->id == resp.id) { - knotif = cur; - break; - } - } - + knotif = find_notification(filter, resp.id); if (!knotif) { ret = -ENOENT; goto out; @@ -1150,7 +1155,7 @@ static long seccomp_notify_send(struct seccomp_filter *filter, static long seccomp_notify_id_valid(struct seccomp_filter *filter, void __user *buf) { - struct seccomp_knotif *knotif = NULL; + struct seccomp_knotif *knotif; u64 id; long ret; @@ -1161,16 +1166,12 @@ static long seccomp_notify_id_valid(struct seccomp_filter *filter, if (ret < 0) return ret; - ret = -ENOENT; - list_for_each_entry(knotif, &filter->notif->notifications, list) { - if (knotif->id == id) { - if (knotif->state == SECCOMP_NOTIFY_SENT) - ret = 0; - goto out; - } - } + knotif = find_notification(filter, id); + if (knotif && knotif->state == SECCOMP_NOTIFY_SENT) + ret = 0; + else + ret = -ENOENT; -out: mutex_unlock(&filter->notify_lock); return ret; } -- 2.25.1 ^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH v3] seccomp: Add find_notification helper 2020-06-01 11:25 [PATCH v3] seccomp: Add find_notification helper Sargun Dhillon @ 2020-06-01 18:26 ` Kees Cook 2020-06-17 20:08 ` Nathan Chancellor 1 sibling, 0 replies; 6+ messages in thread From: Kees Cook @ 2020-06-01 18:26 UTC (permalink / raw) To: Sargun Dhillon Cc: containers, linux-api, linux-kernel, viro, christian.brauner, cyphar, jannh, jeffv, palmer, rsesek, tycho, Matt Denton On Mon, Jun 01, 2020 at 04:25:32AM -0700, Sargun Dhillon wrote: > This adds a helper which can iterate through a seccomp_filter to > find a notification matching an ID. It removes several replicated > chunks of code. > > Signed-off-by: Sargun Dhillon <sargun@sargun.me> > Acked-by: Christian Brauner <christian.brauner@ubuntu.com> > Reviewed-by: Tycho Andersen <tycho@tycho.ws> > Cc: Matt Denton <mpdenton@google.com> > Cc: Kees Cook <keescook@google.com>, > Cc: Jann Horn <jannh@google.com>, > Cc: Robert Sesek <rsesek@google.com>, > Cc: Chris Palmer <palmer@google.com> > Cc: Christian Brauner <christian.brauner@ubuntu.com> > Cc: Tycho Andersen <tycho@tycho.ws> Thanks! Applied to for-next/seccomp. -- Kees Cook ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v3] seccomp: Add find_notification helper 2020-06-01 11:25 [PATCH v3] seccomp: Add find_notification helper Sargun Dhillon 2020-06-01 18:26 ` Kees Cook @ 2020-06-17 20:08 ` Nathan Chancellor 2020-06-17 21:22 ` Kees Cook 2020-06-18 5:44 ` Sargun Dhillon 1 sibling, 2 replies; 6+ messages in thread From: Nathan Chancellor @ 2020-06-17 20:08 UTC (permalink / raw) To: Sargun Dhillon Cc: containers, keescook, linux-api, linux-kernel, viro, christian.brauner, cyphar, jannh, jeffv, palmer, rsesek, tycho, Matt Denton, Kees Cook On Mon, Jun 01, 2020 at 04:25:32AM -0700, Sargun Dhillon wrote: > This adds a helper which can iterate through a seccomp_filter to > find a notification matching an ID. It removes several replicated > chunks of code. > > Signed-off-by: Sargun Dhillon <sargun@sargun.me> > Acked-by: Christian Brauner <christian.brauner@ubuntu.com> > Reviewed-by: Tycho Andersen <tycho@tycho.ws> > Cc: Matt Denton <mpdenton@google.com> > Cc: Kees Cook <keescook@google.com>, > Cc: Jann Horn <jannh@google.com>, > Cc: Robert Sesek <rsesek@google.com>, > Cc: Chris Palmer <palmer@google.com> > Cc: Christian Brauner <christian.brauner@ubuntu.com> > Cc: Tycho Andersen <tycho@tycho.ws> > --- > kernel/seccomp.c | 55 ++++++++++++++++++++++++------------------------ > 1 file changed, 28 insertions(+), 27 deletions(-) > > diff --git a/kernel/seccomp.c b/kernel/seccomp.c > index 55a6184f5990..cc6b47173a95 100644 > --- a/kernel/seccomp.c > +++ b/kernel/seccomp.c > @@ -41,6 +41,7 @@ > #include <linux/tracehook.h> > #include <linux/uaccess.h> > #include <linux/anon_inodes.h> > +#include <linux/lockdep.h> > > enum notify_state { > SECCOMP_NOTIFY_INIT, > @@ -1021,10 +1022,27 @@ static int seccomp_notify_release(struct inode *inode, struct file *file) > return 0; > } > > +/* must be called with notif_lock held */ > +static inline struct seccomp_knotif * > +find_notification(struct seccomp_filter *filter, u64 id) > +{ > + struct seccomp_knotif *cur; > + > + lockdep_assert_held(&filter->notify_lock); > + > + list_for_each_entry(cur, &filter->notif->notifications, list) { > + if (cur->id == id) > + return cur; > + } > + > + return NULL; > +} > + > + > static long seccomp_notify_recv(struct seccomp_filter *filter, > void __user *buf) > { > - struct seccomp_knotif *knotif = NULL, *cur; > + struct seccomp_knotif *knotif, *cur; > struct seccomp_notif unotif; > ssize_t ret; > > @@ -1078,15 +1096,8 @@ static long seccomp_notify_recv(struct seccomp_filter *filter, > * may have died when we released the lock, so we need to make > * sure it's still around. > */ > - knotif = NULL; > mutex_lock(&filter->notify_lock); > - list_for_each_entry(cur, &filter->notif->notifications, list) { > - if (cur->id == unotif.id) { > - knotif = cur; > - break; > - } > - } > - > + knotif = find_notification(filter, unotif.id); > if (knotif) { > knotif->state = SECCOMP_NOTIFY_INIT; > up(&filter->notif->request); > @@ -1101,7 +1112,7 @@ static long seccomp_notify_send(struct seccomp_filter *filter, > void __user *buf) > { > struct seccomp_notif_resp resp = {}; > - struct seccomp_knotif *knotif = NULL, *cur; > + struct seccomp_knotif *knotif; > long ret; > > if (copy_from_user(&resp, buf, sizeof(resp))) > @@ -1118,13 +1129,7 @@ static long seccomp_notify_send(struct seccomp_filter *filter, > if (ret < 0) > return ret; > > - list_for_each_entry(cur, &filter->notif->notifications, list) { > - if (cur->id == resp.id) { > - knotif = cur; > - break; > - } > - } > - > + knotif = find_notification(filter, resp.id); > if (!knotif) { > ret = -ENOENT; > goto out; > @@ -1150,7 +1155,7 @@ static long seccomp_notify_send(struct seccomp_filter *filter, > static long seccomp_notify_id_valid(struct seccomp_filter *filter, > void __user *buf) > { > - struct seccomp_knotif *knotif = NULL; I don't know that this should have been removed, clang now warns: kernel/seccomp.c:1063:2: warning: variable 'knotif' is used uninitialized whenever 'for' loop exits because its condition is false [-Wsometimes-uninitialized] list_for_each_entry(cur, &filter->notif->notifications, list) { ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ include/linux/list.h:602:7: note: expanded from macro 'list_for_each_entry' &pos->member != (head); \ ^~~~~~~~~~~~~~~~~~~~~~ kernel/seccomp.c:1075:7: note: uninitialized use occurs here if (!knotif) { ^~~~~~ kernel/seccomp.c:1063:2: note: remove the condition if it is always true list_for_each_entry(cur, &filter->notif->notifications, list) { ^ include/linux/list.h:602:7: note: expanded from macro 'list_for_each_entry' &pos->member != (head); \ ^ kernel/seccomp.c:1045:31: note: initialize the variable 'knotif' to silence this warning struct seccomp_knotif *knotif, *cur; ^ = NULL 1 warning generated. > + struct seccomp_knotif *knotif; > u64 id; > long ret; > > @@ -1161,16 +1166,12 @@ static long seccomp_notify_id_valid(struct seccomp_filter *filter, > if (ret < 0) > return ret; > > - ret = -ENOENT; > - list_for_each_entry(knotif, &filter->notif->notifications, list) { > - if (knotif->id == id) { > - if (knotif->state == SECCOMP_NOTIFY_SENT) > - ret = 0; > - goto out; > - } > - } > + knotif = find_notification(filter, id); > + if (knotif && knotif->state == SECCOMP_NOTIFY_SENT) > + ret = 0; > + else > + ret = -ENOENT; > > -out: > mutex_unlock(&filter->notify_lock); > return ret; > } > -- > 2.25.1 > Cheers, Nathan ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v3] seccomp: Add find_notification helper 2020-06-17 20:08 ` Nathan Chancellor @ 2020-06-17 21:22 ` Kees Cook 2020-06-18 5:44 ` Sargun Dhillon 1 sibling, 0 replies; 6+ messages in thread From: Kees Cook @ 2020-06-17 21:22 UTC (permalink / raw) To: Nathan Chancellor Cc: Sargun Dhillon, containers, linux-api, linux-kernel, viro, christian.brauner, cyphar, jannh, jeffv, palmer, rsesek, tycho, Matt Denton On Wed, Jun 17, 2020 at 01:08:44PM -0700, Nathan Chancellor wrote: > On Mon, Jun 01, 2020 at 04:25:32AM -0700, Sargun Dhillon wrote: > > [...] > > static long seccomp_notify_recv(struct seccomp_filter *filter, > > void __user *buf) > > { > > - struct seccomp_knotif *knotif = NULL, *cur; > > + struct seccomp_knotif *knotif, *cur; > > struct seccomp_notif unotif; > > ssize_t ret; > > > > I don't know that this should have been removed, clang now warns: > > kernel/seccomp.c:1063:2: warning: variable 'knotif' is used uninitialized whenever 'for' loop exits because its condition is false [-Wsometimes-uninitialized] > list_for_each_entry(cur, &filter->notif->notifications, list) { > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > include/linux/list.h:602:7: note: expanded from macro 'list_for_each_entry' > &pos->member != (head); \ > ^~~~~~~~~~~~~~~~~~~~~~ > kernel/seccomp.c:1075:7: note: uninitialized use occurs here > if (!knotif) { > ^~~~~~ > kernel/seccomp.c:1063:2: note: remove the condition if it is always true > list_for_each_entry(cur, &filter->notif->notifications, list) { > ^ > include/linux/list.h:602:7: note: expanded from macro 'list_for_each_entry' > &pos->member != (head); \ > ^ > kernel/seccomp.c:1045:31: note: initialize the variable 'knotif' to silence this warning > struct seccomp_knotif *knotif, *cur; > ^ > = NULL > 1 warning generated. Eek; yes, thank you! I've folded the fix into Sargun's patch. -- Kees Cook ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v3] seccomp: Add find_notification helper 2020-06-17 20:08 ` Nathan Chancellor 2020-06-17 21:22 ` Kees Cook @ 2020-06-18 5:44 ` Sargun Dhillon 2020-06-18 6:04 ` Nathan Chancellor 1 sibling, 1 reply; 6+ messages in thread From: Sargun Dhillon @ 2020-06-18 5:44 UTC (permalink / raw) To: Nathan Chancellor Cc: containers, keescook, linux-api, linux-kernel, viro, christian.brauner, cyphar, jannh, jeffv, palmer, rsesek, tycho, Matt Denton, Kees Cook On Wed, Jun 17, 2020 at 01:08:44PM -0700, Nathan Chancellor wrote: > On Mon, Jun 01, 2020 at 04:25:32AM -0700, Sargun Dhillon wrote: > > This adds a helper which can iterate through a seccomp_filter to > > find a notification matching an ID. It removes several replicated > > chunks of code. > > > > Signed-off-by: Sargun Dhillon <sargun@sargun.me> > > Acked-by: Christian Brauner <christian.brauner@ubuntu.com> > > Reviewed-by: Tycho Andersen <tycho@tycho.ws> > > Cc: Matt Denton <mpdenton@google.com> > > Cc: Kees Cook <keescook@google.com>, > > Cc: Jann Horn <jannh@google.com>, > > Cc: Robert Sesek <rsesek@google.com>, > > Cc: Chris Palmer <palmer@google.com> > > Cc: Christian Brauner <christian.brauner@ubuntu.com> > > Cc: Tycho Andersen <tycho@tycho.ws> > > --- > > kernel/seccomp.c | 55 ++++++++++++++++++++++++------------------------ > > 1 file changed, 28 insertions(+), 27 deletions(-) > > > > diff --git a/kernel/seccomp.c b/kernel/seccomp.c > > index 55a6184f5990..cc6b47173a95 100644 > > --- a/kernel/seccomp.c > > +++ b/kernel/seccomp.c > > @@ -41,6 +41,7 @@ > > #include <linux/tracehook.h> > > #include <linux/uaccess.h> > > #include <linux/anon_inodes.h> > > +#include <linux/lockdep.h> > > > > enum notify_state { > > SECCOMP_NOTIFY_INIT, > > @@ -1021,10 +1022,27 @@ static int seccomp_notify_release(struct inode *inode, struct file *file) > > return 0; > > } > > > > +/* must be called with notif_lock held */ > > +static inline struct seccomp_knotif * > > +find_notification(struct seccomp_filter *filter, u64 id) > > +{ > > + struct seccomp_knotif *cur; > > + > > + lockdep_assert_held(&filter->notify_lock); > > + > > + list_for_each_entry(cur, &filter->notif->notifications, list) { > > + if (cur->id == id) > > + return cur; > > + } > > + > > + return NULL; > > +} > > + > > + > > static long seccomp_notify_recv(struct seccomp_filter *filter, > > void __user *buf) > > { > > - struct seccomp_knotif *knotif = NULL, *cur; > > + struct seccomp_knotif *knotif, *cur; > > struct seccomp_notif unotif; > > ssize_t ret; > > > > @@ -1078,15 +1096,8 @@ static long seccomp_notify_recv(struct seccomp_filter *filter, > > * may have died when we released the lock, so we need to make > > * sure it's still around. > > */ > > - knotif = NULL; > > mutex_lock(&filter->notify_lock); > > - list_for_each_entry(cur, &filter->notif->notifications, list) { > > - if (cur->id == unotif.id) { > > - knotif = cur; > > - break; > > - } > > - } > > - > > + knotif = find_notification(filter, unotif.id); > > if (knotif) { > > knotif->state = SECCOMP_NOTIFY_INIT; > > up(&filter->notif->request); > > @@ -1101,7 +1112,7 @@ static long seccomp_notify_send(struct seccomp_filter *filter, > > void __user *buf) > > { > > struct seccomp_notif_resp resp = {}; > > - struct seccomp_knotif *knotif = NULL, *cur; > > + struct seccomp_knotif *knotif; > > long ret; > > > > if (copy_from_user(&resp, buf, sizeof(resp))) > > @@ -1118,13 +1129,7 @@ static long seccomp_notify_send(struct seccomp_filter *filter, > > if (ret < 0) > > return ret; > > > > - list_for_each_entry(cur, &filter->notif->notifications, list) { > > - if (cur->id == resp.id) { > > - knotif = cur; > > - break; > > - } > > - } > > - > > + knotif = find_notification(filter, resp.id); > > if (!knotif) { > > ret = -ENOENT; > > goto out; > > @@ -1150,7 +1155,7 @@ static long seccomp_notify_send(struct seccomp_filter *filter, > > static long seccomp_notify_id_valid(struct seccomp_filter *filter, > > void __user *buf) > > { > > - struct seccomp_knotif *knotif = NULL; > > I don't know that this should have been removed, clang now warns: > > kernel/seccomp.c:1063:2: warning: variable 'knotif' is used uninitialized whenever 'for' loop exits because its condition is false [-Wsometimes-uninitialized] > list_for_each_entry(cur, &filter->notif->notifications, list) { > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > include/linux/list.h:602:7: note: expanded from macro 'list_for_each_entry' > &pos->member != (head); \ > ^~~~~~~~~~~~~~~~~~~~~~ > kernel/seccomp.c:1075:7: note: uninitialized use occurs here > if (!knotif) { > ^~~~~~ > kernel/seccomp.c:1063:2: note: remove the condition if it is always true > list_for_each_entry(cur, &filter->notif->notifications, list) { > ^ > include/linux/list.h:602:7: note: expanded from macro 'list_for_each_entry' > &pos->member != (head); \ > ^ > kernel/seccomp.c:1045:31: note: initialize the variable 'knotif' to silence this warning > struct seccomp_knotif *knotif, *cur; > ^ > = NULL > 1 warning generated. > I'm curious as to how you got clang to generate this warning. I'm running with clang 10, and upon running with V=1, and adding -Wsometimes-uninitialized, I'm not seeing this warning. The following is the command called: /usr/bin/clang-10 -Wp,-MD,kernel/.seccomp.o.d -nostdinc -isystem /usr/lib/llvm-10/lib/clang/10.0.0/include -I./arch/x86/include -I./arch/x86/include/generated -I./include -I./arch/x86/include/uapi -I./arch/x86/include/generated/uapi -I./include/uapi -I./include/generated/uapi -include ./include/linux/kconfig.h -include ./include/linux/compiler_types.h -D__KERNEL__ -Qunused-arguments -Wsometimes-uninitialized -Wall -Wundef -Werror=strict-prototypes -Wno-trigraphs -fno-strict-aliasing -fno-common -fshort-wchar -fno-PIE -Werror=implicit-function-declaration -Werror=implicit-int -Wno-format-security -std=gnu89 -no-integrated-as -Werror=unknown-warning-option -mno-sse -mno-mmx -mno-sse2 -mno-3dnow -mno-avx -m64 -mno-80387 -mstack-alignment=8 -mtune=generic -mno-red-zone -mcmodel=kernel -DCONFIG_X86_X32_ABI -Wno-sign-compare -fno-asynchronous-unwind-tables -mretpoline-external-thunk -fno-delete-null-pointer-checks -Wno-address-of-packed-member -O2 -Wframe-larger-than=1024 -fstack-protector -Wno-format-invalid-specifier -Wno-gnu -mno-global-merge -Wno-unused-const-variable -g -pg -mfentry -DCC_USING_FENTRY -Wdeclaration-after-statement -Wvla -Wno-pointer-sign -Wno-array-bounds -fno-strict-overflow -fno-merge-all-constants -fno-stack-check -Werror=date-time -Werror=incompatible-pointer-types -fmacro-prefix-map=./= -fcf-protection=none -Wno-initializer-overrides -Wno-format -Wno-sign-compare -Wno-format-zero-length -Wno-tautological-constant-out-of-range-compare -DKBUILD_MODFILE='"kernel/seccomp"' -DKBUILD_BASENAME='"seccomp"' -DKBUILD_MODNAME='"seccomp"' -c -o kernel/seccomp.o kernel/seccomp.c > > + struct seccomp_knotif *knotif; > > u64 id; > > long ret; > > > > @@ -1161,16 +1166,12 @@ static long seccomp_notify_id_valid(struct seccomp_filter *filter, > > if (ret < 0) > > return ret; > > > > - ret = -ENOENT; > > - list_for_each_entry(knotif, &filter->notif->notifications, list) { > > - if (knotif->id == id) { > > - if (knotif->state == SECCOMP_NOTIFY_SENT) > > - ret = 0; > > - goto out; > > - } > > - } > > + knotif = find_notification(filter, id); > > + if (knotif && knotif->state == SECCOMP_NOTIFY_SENT) > > + ret = 0; > > + else > > + ret = -ENOENT; > > > > -out: > > mutex_unlock(&filter->notify_lock); > > return ret; > > } > > -- > > 2.25.1 > > > > Cheers, > Nathan ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH v3] seccomp: Add find_notification helper 2020-06-18 5:44 ` Sargun Dhillon @ 2020-06-18 6:04 ` Nathan Chancellor 0 siblings, 0 replies; 6+ messages in thread From: Nathan Chancellor @ 2020-06-18 6:04 UTC (permalink / raw) To: Sargun Dhillon Cc: containers, keescook, linux-api, linux-kernel, viro, christian.brauner, cyphar, jannh, jeffv, palmer, rsesek, tycho, Matt Denton, Kees Cook On Thu, Jun 18, 2020 at 05:44:14AM +0000, Sargun Dhillon wrote: > On Wed, Jun 17, 2020 at 01:08:44PM -0700, Nathan Chancellor wrote: > > On Mon, Jun 01, 2020 at 04:25:32AM -0700, Sargun Dhillon wrote: > > > This adds a helper which can iterate through a seccomp_filter to > > > find a notification matching an ID. It removes several replicated > > > chunks of code. > > > > > > Signed-off-by: Sargun Dhillon <sargun@sargun.me> > > > Acked-by: Christian Brauner <christian.brauner@ubuntu.com> > > > Reviewed-by: Tycho Andersen <tycho@tycho.ws> > > > Cc: Matt Denton <mpdenton@google.com> > > > Cc: Kees Cook <keescook@google.com>, > > > Cc: Jann Horn <jannh@google.com>, > > > Cc: Robert Sesek <rsesek@google.com>, > > > Cc: Chris Palmer <palmer@google.com> > > > Cc: Christian Brauner <christian.brauner@ubuntu.com> > > > Cc: Tycho Andersen <tycho@tycho.ws> > > > --- > > > kernel/seccomp.c | 55 ++++++++++++++++++++++++------------------------ > > > 1 file changed, 28 insertions(+), 27 deletions(-) > > > > > > diff --git a/kernel/seccomp.c b/kernel/seccomp.c > > > index 55a6184f5990..cc6b47173a95 100644 > > > --- a/kernel/seccomp.c > > > +++ b/kernel/seccomp.c > > > @@ -41,6 +41,7 @@ > > > #include <linux/tracehook.h> > > > #include <linux/uaccess.h> > > > #include <linux/anon_inodes.h> > > > +#include <linux/lockdep.h> > > > > > > enum notify_state { > > > SECCOMP_NOTIFY_INIT, > > > @@ -1021,10 +1022,27 @@ static int seccomp_notify_release(struct inode *inode, struct file *file) > > > return 0; > > > } > > > > > > +/* must be called with notif_lock held */ > > > +static inline struct seccomp_knotif * > > > +find_notification(struct seccomp_filter *filter, u64 id) > > > +{ > > > + struct seccomp_knotif *cur; > > > + > > > + lockdep_assert_held(&filter->notify_lock); > > > + > > > + list_for_each_entry(cur, &filter->notif->notifications, list) { > > > + if (cur->id == id) > > > + return cur; > > > + } > > > + > > > + return NULL; > > > +} > > > + > > > + > > > static long seccomp_notify_recv(struct seccomp_filter *filter, > > > void __user *buf) > > > { > > > - struct seccomp_knotif *knotif = NULL, *cur; > > > + struct seccomp_knotif *knotif, *cur; > > > struct seccomp_notif unotif; > > > ssize_t ret; > > > > > > @@ -1078,15 +1096,8 @@ static long seccomp_notify_recv(struct seccomp_filter *filter, > > > * may have died when we released the lock, so we need to make > > > * sure it's still around. > > > */ > > > - knotif = NULL; > > > mutex_lock(&filter->notify_lock); > > > - list_for_each_entry(cur, &filter->notif->notifications, list) { > > > - if (cur->id == unotif.id) { > > > - knotif = cur; > > > - break; > > > - } > > > - } > > > - > > > + knotif = find_notification(filter, unotif.id); > > > if (knotif) { > > > knotif->state = SECCOMP_NOTIFY_INIT; > > > up(&filter->notif->request); > > > @@ -1101,7 +1112,7 @@ static long seccomp_notify_send(struct seccomp_filter *filter, > > > void __user *buf) > > > { > > > struct seccomp_notif_resp resp = {}; > > > - struct seccomp_knotif *knotif = NULL, *cur; > > > + struct seccomp_knotif *knotif; > > > long ret; > > > > > > if (copy_from_user(&resp, buf, sizeof(resp))) > > > @@ -1118,13 +1129,7 @@ static long seccomp_notify_send(struct seccomp_filter *filter, > > > if (ret < 0) > > > return ret; > > > > > > - list_for_each_entry(cur, &filter->notif->notifications, list) { > > > - if (cur->id == resp.id) { > > > - knotif = cur; > > > - break; > > > - } > > > - } > > > - > > > + knotif = find_notification(filter, resp.id); > > > if (!knotif) { > > > ret = -ENOENT; > > > goto out; > > > @@ -1150,7 +1155,7 @@ static long seccomp_notify_send(struct seccomp_filter *filter, > > > static long seccomp_notify_id_valid(struct seccomp_filter *filter, > > > void __user *buf) > > > { > > > - struct seccomp_knotif *knotif = NULL; > > > > I don't know that this should have been removed, clang now warns: > > > > kernel/seccomp.c:1063:2: warning: variable 'knotif' is used uninitialized whenever 'for' loop exits because its condition is false [-Wsometimes-uninitialized] > > list_for_each_entry(cur, &filter->notif->notifications, list) { > > ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > include/linux/list.h:602:7: note: expanded from macro 'list_for_each_entry' > > &pos->member != (head); \ > > ^~~~~~~~~~~~~~~~~~~~~~ > > kernel/seccomp.c:1075:7: note: uninitialized use occurs here > > if (!knotif) { > > ^~~~~~ > > kernel/seccomp.c:1063:2: note: remove the condition if it is always true > > list_for_each_entry(cur, &filter->notif->notifications, list) { > > ^ > > include/linux/list.h:602:7: note: expanded from macro 'list_for_each_entry' > > &pos->member != (head); \ > > ^ > > kernel/seccomp.c:1045:31: note: initialize the variable 'knotif' to silence this warning > > struct seccomp_knotif *knotif, *cur; > > ^ > > = NULL > > 1 warning generated. > > > I'm curious as to how you got clang to generate this warning. I'm running with clang 10, and > upon running with V=1, and adding -Wsometimes-uninitialized, I'm not seeing this warning. > The following is the command called: > /usr/bin/clang-10 -Wp,-MD,kernel/.seccomp.o.d -nostdinc -isystem /usr/lib/llvm-10/lib/clang/10.0.0/include -I./arch/x86/include -I./arch/x86/include/generated -I./include -I./arch/x86/include/uapi -I./arch/x86/include/generated/uapi -I./include/uapi -I./include/generated/uapi -include ./include/linux/kconfig.h -include ./include/linux/compiler_types.h -D__KERNEL__ -Qunused-arguments -Wsometimes-uninitialized -Wall -Wundef -Werror=strict-prototypes -Wno-trigraphs -fno-strict-aliasing -fno-common -fshort-wchar -fno-PIE -Werror=implicit-function-declaration -Werror=implicit-int -Wno-format-security -std=gnu89 -no-integrated-as -Werror=unknown-warning-option -mno-sse -mno-mmx -mno-sse2 -mno-3dnow -mno-avx -m64 -mno-80387 -mstack-alignment=8 -mtune=generic -mno-red-zone -mcmodel=kernel -DCONFIG_X86_X32_ABI -Wno-sign-compare -fno-asynchronous-unwind-tables -mretpoline-external-thunk -fno-delete-null-pointer-checks -Wno-address-of-packed-member -O2 -Wframe-larger-than=1024 -fstack-protector -Wno-format-invalid-specifier -Wno-gnu -mno-global-merge -Wno-unused-const-variable -g -pg -mfentry -DCC_USING_FENTRY -Wdeclaration-after-statement -Wvla -Wno-pointer-sign -Wno-array-bounds -fno-strict-overflow -fno-merge-all-constants -fno-stack-check -Werror=date-time -Werror=incompatible-pointer-types -fmacro-prefix-map=./= -fcf-protection=none -Wno-initializer-overrides -Wno-format -Wno-sign-compare -Wno-format-zero-length -Wno-tautological-constant-out-of-range-compare -DKBUILD_MODFILE='"kernel/seccomp"' -DKBUILD_BASENAME='"seccomp"' -DKBUILD_MODNAME='"seccomp"' -c -o kernel/seccomp.o kernel/seccomp.c I saw it on a variety of configs but the one that is probably the easiest to reproduce with is arm32 defconfig: $ curl -LSs https://lore.kernel.org/lkml/20200601112532.150158-1-sargun@sargun.me/raw | git am $ make -skj"$(nproc)" ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- LLVM=1 O=out/arm distclean defconfig kernel/seccomp.o Cheers, Nathan > > > + struct seccomp_knotif *knotif; > > > u64 id; > > > long ret; > > > > > > @@ -1161,16 +1166,12 @@ static long seccomp_notify_id_valid(struct seccomp_filter *filter, > > > if (ret < 0) > > > return ret; > > > > > > - ret = -ENOENT; > > > - list_for_each_entry(knotif, &filter->notif->notifications, list) { > > > - if (knotif->id == id) { > > > - if (knotif->state == SECCOMP_NOTIFY_SENT) > > > - ret = 0; > > > - goto out; > > > - } > > > - } > > > + knotif = find_notification(filter, id); > > > + if (knotif && knotif->state == SECCOMP_NOTIFY_SENT) > > > + ret = 0; > > > + else > > > + ret = -ENOENT; > > > > > > -out: > > > mutex_unlock(&filter->notify_lock); > > > return ret; > > > } > > > -- > > > 2.25.1 > > > > > > > Cheers, > > Nathan ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2020-06-18 6:04 UTC | newest] Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2020-06-01 11:25 [PATCH v3] seccomp: Add find_notification helper Sargun Dhillon 2020-06-01 18:26 ` Kees Cook 2020-06-17 20:08 ` Nathan Chancellor 2020-06-17 21:22 ` Kees Cook 2020-06-18 5:44 ` Sargun Dhillon 2020-06-18 6:04 ` Nathan Chancellor
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