diff options
| -rw-r--r-- | man/systemd.exec.xml | 11 | ||||
| -rw-r--r-- | src/core/execute.c | 11 |
2 files changed, 18 insertions, 4 deletions
diff --git a/man/systemd.exec.xml b/man/systemd.exec.xml index 6a26f3c133..54ec7e29ca 100644 --- a/man/systemd.exec.xml +++ b/man/systemd.exec.xml @@ -1525,12 +1525,15 @@ <term><varname>MemoryDenyWriteExecute=</varname></term> <listitem><para>Takes a boolean argument. If set, attempts to create memory mappings that are writable and - executable at the same time, or to change existing memory mappings to become executable are prohibited. + executable at the same time, or to change existing memory mappings to become executable, or mapping shared memory + segments as executable are prohibited. Specifically, a system call filter is added that rejects <citerefentry><refentrytitle>mmap</refentrytitle><manvolnum>2</manvolnum></citerefentry> - system calls with both <constant>PROT_EXEC</constant> and <constant>PROT_WRITE</constant> set - and <citerefentry><refentrytitle>mprotect</refentrytitle><manvolnum>2</manvolnum></citerefentry> - system calls with <constant>PROT_EXEC</constant> set. Note that this option is incompatible with programs + system calls with both <constant>PROT_EXEC</constant> and <constant>PROT_WRITE</constant> set, + <citerefentry><refentrytitle>mprotect</refentrytitle><manvolnum>2</manvolnum></citerefentry> + system calls with <constant>PROT_EXEC</constant> set and + <citerefentry><refentrytitle>shmat</refentrytitle><manvolnum>2</manvolnum></citerefentry> + system calls with <constant>SHM_EXEC</constant> set. Note that this option is incompatible with programs that generate program code dynamically at runtime, such as JIT execution engines, or programs compiled making use of the code "trampoline" feature of various C compilers. This option improves service security, as it makes harder for software exploits to change running code dynamically. diff --git a/src/core/execute.c b/src/core/execute.c index 7f343c4902..ae9df41b99 100644 --- a/src/core/execute.c +++ b/src/core/execute.c @@ -29,8 +29,10 @@ #include <sys/mman.h> #include <sys/personality.h> #include <sys/prctl.h> +#include <sys/shm.h> #include <sys/socket.h> #include <sys/stat.h> +#include <sys/types.h> #include <sys/un.h> #include <unistd.h> #include <utmpx.h> @@ -1394,6 +1396,15 @@ static int apply_memory_deny_write_execute(const Unit* u, const ExecContext *c) if (r < 0) goto finish; + r = seccomp_rule_add( + seccomp, + SCMP_ACT_ERRNO(EPERM), + SCMP_SYS(shmat), + 1, + SCMP_A2(SCMP_CMP_MASKED_EQ, SHM_EXEC, SHM_EXEC)); + if (r < 0) + goto finish; + r = seccomp_load(seccomp); finish: |