| Message ID | 20210216211328.3609-1-nicolas.iooss@m4x.org (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
| Series | libselinux: rename gettid() to something which never conflicts with the libc | expand |
Nicolas Iooss <nicolas.iooss@m4x.org> writes: > Musl recently added a wrapper for gettid() syscall. There is no way to > detect this new version in a reliable way, so rename our gettid() > wrapper to a non-conflicting name. > > Introduce a new function which, when using a libc known to provide a > wrapper for gettid(), calls it, and which, otherwise, performs the > syscall directly. > > Anyway this function is only used on systems where /proc/thread-self > does not exist, which are therefore running Linux<3.17. > > Fixes: https://github.com/SELinuxProject/selinux/issues/282 > Signed-off-by: Nicolas Iooss <nicolas.iooss@m4x.org> Tested on Fedora with musl-1.2.22 scratch build https://koji.fedoraproject.org/koji/taskinfo?taskID=62214131 : Before ^&^ musl-gcc -D_GNU_SOURCE -I../include procattr.c -c procattr.c:38:14: error: static declaration of ‘gettid’ follows non-static declaration 38 | static pid_t gettid(void) | ^~~~~~ In file included from procattr.c:2: /usr/x86_64-linux-musl/include/unistd.h:194:7: note: previous declaration of ‘gettid’ with type ‘pid_t(void)’ {aka ‘int(void)’} 194 | pid_t gettid(void); | ^~~~~~ After ^&^ musl-gcc -D_GNU_SOURCE -I../include procattr.c -c Seems to work. Thanks! Acked-by: Petr Lautrbach <plautrba@redhat.com> > diff --git a/libselinux/src/procattr.c b/libselinux/src/procattr.c > index 1aa67ac53f39..840570525f5f 100644 > --- a/libselinux/src/procattr.c > +++ b/libselinux/src/procattr.c > @@ -25,21 +25,23 @@ static __thread char destructor_initialized; > /* Bionic and glibc >= 2.30 declare gettid() system call wrapper in unistd.h and > * has a definition for it */ > #ifdef __BIONIC__ > - #define OVERRIDE_GETTID 0 > + #define HAVE_GETTID 1 > #elif !defined(__GLIBC_PREREQ) > - #define OVERRIDE_GETTID 1 > + #define HAVE_GETTID 0 > #elif !__GLIBC_PREREQ(2,30) > - #define OVERRIDE_GETTID 1 > + #define HAVE_GETTID 0 > #else > - #define OVERRIDE_GETTID 0 > + #define HAVE_GETTID 1 > #endif > > -#if OVERRIDE_GETTID > -static pid_t gettid(void) > +static pid_t selinux_gettid(void) > { > +#if HAVE_GETTID > + return gettid(); > +#else > return syscall(__NR_gettid); > -} > #endif > +} > > static void procattr_thread_destructor(void __attribute__((unused)) *unused) > { > @@ -94,7 +96,7 @@ static int openattr(pid_t pid, const char *attr, int flags) > if (fd >= 0 || errno != ENOENT) > goto out; > free(path); > - tid = gettid(); > + tid = selinux_gettid(); > rc = asprintf(&path, "/proc/self/task/%d/attr/%s", tid, attr); > } else { > errno = EINVAL; > -- > 2.30.0
Petr Lautrbach <plautrba@redhat.com> writes: > Nicolas Iooss <nicolas.iooss@m4x.org> writes: > >> Musl recently added a wrapper for gettid() syscall. There is no way to >> detect this new version in a reliable way, so rename our gettid() >> wrapper to a non-conflicting name. >> >> Introduce a new function which, when using a libc known to provide a >> wrapper for gettid(), calls it, and which, otherwise, performs the >> syscall directly. >> >> Anyway this function is only used on systems where /proc/thread-self >> does not exist, which are therefore running Linux<3.17. >> >> Fixes: https://github.com/SELinuxProject/selinux/issues/282 >> Signed-off-by: Nicolas Iooss <nicolas.iooss@m4x.org> > > Tested on Fedora with musl-1.2.22 scratch build > https://koji.fedoraproject.org/koji/taskinfo?taskID=62214131 : > > Before > ^&^ musl-gcc -D_GNU_SOURCE -I../include procattr.c -c > procattr.c:38:14: error: static declaration of ‘gettid’ follows non-static declaration > 38 | static pid_t gettid(void) > | ^~~~~~ > In file included from procattr.c:2: > /usr/x86_64-linux-musl/include/unistd.h:194:7: note: previous declaration of ‘gettid’ with type ‘pid_t(void)’ {aka ‘int(void)’} > 194 | pid_t gettid(void); > | ^~~~~~ > > > After > ^&^ musl-gcc -D_GNU_SOURCE -I../include procattr.c -c > > > Seems to work. Thanks! > > Acked-by: Petr Lautrbach <plautrba@redhat.com> > Merged. > >> diff --git a/libselinux/src/procattr.c b/libselinux/src/procattr.c >> index 1aa67ac53f39..840570525f5f 100644 >> --- a/libselinux/src/procattr.c >> +++ b/libselinux/src/procattr.c >> @@ -25,21 +25,23 @@ static __thread char destructor_initialized; >> /* Bionic and glibc >= 2.30 declare gettid() system call wrapper in unistd.h and >> * has a definition for it */ >> #ifdef __BIONIC__ >> - #define OVERRIDE_GETTID 0 >> + #define HAVE_GETTID 1 >> #elif !defined(__GLIBC_PREREQ) >> - #define OVERRIDE_GETTID 1 >> + #define HAVE_GETTID 0 >> #elif !__GLIBC_PREREQ(2,30) >> - #define OVERRIDE_GETTID 1 >> + #define HAVE_GETTID 0 >> #else >> - #define OVERRIDE_GETTID 0 >> + #define HAVE_GETTID 1 >> #endif >> >> -#if OVERRIDE_GETTID >> -static pid_t gettid(void) >> +static pid_t selinux_gettid(void) >> { >> +#if HAVE_GETTID >> + return gettid(); >> +#else >> return syscall(__NR_gettid); >> -} >> #endif >> +} >> >> static void procattr_thread_destructor(void __attribute__((unused)) *unused) >> { >> @@ -94,7 +96,7 @@ static int openattr(pid_t pid, const char *attr, int flags) >> if (fd >= 0 || errno != ENOENT) >> goto out; >> free(path); >> - tid = gettid(); >> + tid = selinux_gettid(); >> rc = asprintf(&path, "/proc/self/task/%d/attr/%s", tid, attr); >> } else { >> errno = EINVAL; >> -- >> 2.30.0
diff --git a/libselinux/src/procattr.c b/libselinux/src/procattr.c index 1aa67ac53f39..840570525f5f 100644 --- a/libselinux/src/procattr.c +++ b/libselinux/src/procattr.c @@ -25,21 +25,23 @@ static __thread char destructor_initialized; /* Bionic and glibc >= 2.30 declare gettid() system call wrapper in unistd.h and * has a definition for it */ #ifdef __BIONIC__ - #define OVERRIDE_GETTID 0 + #define HAVE_GETTID 1 #elif !defined(__GLIBC_PREREQ) - #define OVERRIDE_GETTID 1 + #define HAVE_GETTID 0 #elif !__GLIBC_PREREQ(2,30) - #define OVERRIDE_GETTID 1 + #define HAVE_GETTID 0 #else - #define OVERRIDE_GETTID 0 + #define HAVE_GETTID 1 #endif -#if OVERRIDE_GETTID -static pid_t gettid(void) +static pid_t selinux_gettid(void) { +#if HAVE_GETTID + return gettid(); +#else return syscall(__NR_gettid); -} #endif +} static void procattr_thread_destructor(void __attribute__((unused)) *unused) { @@ -94,7 +96,7 @@ static int openattr(pid_t pid, const char *attr, int flags) if (fd >= 0 || errno != ENOENT) goto out; free(path); - tid = gettid(); + tid = selinux_gettid(); rc = asprintf(&path, "/proc/self/task/%d/attr/%s", tid, attr); } else { errno = EINVAL;
Musl recently added a wrapper for gettid() syscall. There is no way to detect this new version in a reliable way, so rename our gettid() wrapper to a non-conflicting name. Introduce a new function which, when using a libc known to provide a wrapper for gettid(), calls it, and which, otherwise, performs the syscall directly. Anyway this function is only used on systems where /proc/thread-self does not exist, which are therefore running Linux<3.17. Fixes: https://github.com/SELinuxProject/selinux/issues/282 Signed-off-by: Nicolas Iooss <nicolas.iooss@m4x.org>