Begin landlock support
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bb02e40101
194
qssb.h
194
qssb.h
@ -50,6 +50,9 @@
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#endif
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#if HAVE_LANDLOCK == 1
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#include <linux/landlock.h>
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#if LANDLOCK_CREATE_RULESET_VERSION != (1U << 0)
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#error "This landlock ABI version is not supported by qssb (yet)"
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#endif
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#endif
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//TODO: stolen from kernel samples/seccomp, GPLv2...?
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@ -96,8 +99,36 @@
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#define QSSB_FS_ALLOW_MAKE_FIFO (1 << 13)
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#define QSSB_FS_ALLOW_MAKE_BLOCK (1 << 14)
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#define QSSB_FS_ALLOW_MAKE_SYM (1 << 15)
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#define QSSB_FS_ALLOW_WRITE_FILE (1 << 16)
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#define QSSB_FS_ALLOW_READ_DIR (1 << 17)
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#define QSSB_FS_ALLOW_REMOVE (1 << 18)
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#ifndef landlock_create_ruleset
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static inline int landlock_create_ruleset(
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const struct landlock_ruleset_attr *const attr,
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const size_t size, const __u32 flags)
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{
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return syscall(__NR_landlock_create_ruleset, attr, size, flags);
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}
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#endif
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#ifndef landlock_add_rule
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static inline int landlock_add_rule(const int ruleset_fd,
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const enum landlock_rule_type rule_type,
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const void *const rule_attr, const __u32 flags)
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{
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return syscall(__NR_landlock_add_rule, ruleset_fd, rule_type,
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rule_attr, flags);
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}
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#endif
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#ifndef landlock_restrict_self
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static inline int landlock_restrict_self(const int ruleset_fd,
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const __u32 flags)
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{
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return syscall(__NR_landlock_restrict_self, ruleset_fd, flags);
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}
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#endif
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#endif
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/* Most exploits have more need for those syscalls than the
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* exploited programs. In cases they are needed, this list should be
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@ -146,7 +177,6 @@ struct qssb_policy
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struct qssb_path_policy *path_policies;
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};
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/* Creates the default policy
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* Must be freed using qssb_free_policy
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* @returns: default policy */
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@ -190,8 +220,8 @@ int random_string(char *buffer, size_t buffer_length)
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}
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/* Creates a directory and all necessary parent directories
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*
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/* Creates a directory and all necessary parent directories
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*
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* @returns: 0 on success, -ERRNO on failure
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* */
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static int mkdir_structure(const char *p, mode_t mode)
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@ -212,7 +242,7 @@ static int mkdir_structure(const char *p, mode_t mode)
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char *begin = path;
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char *end = begin+1;
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while(*end)
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{
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if(*end == '/')
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@ -281,7 +311,7 @@ static int get_policy_mount_flags(struct qssb_path_policy *policy)
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/* Helper to mount directories into the chroot path "chroot_target_path"
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* Paths will be created if necessary
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* @returns: 0 on sucess, -ERRNO on failure */
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static int mount_to_chroot(const char *chroot_target_path, struct qssb_path_policy *path_policy)
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{
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@ -373,7 +403,7 @@ static int enter_namespaces(int namespace_options)
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fp = fopen("/proc/self/uid_map", "w");
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fprintf(fp, "0 %i", current_uid);
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fclose(fp);
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fclose(fp);
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fp = fopen("/proc/self/gid_map", "w");
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fprintf(fp, "0 %i", current_gid);
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@ -400,11 +430,11 @@ static int enter_namespaces(int namespace_options)
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}
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}
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return 0;
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return 0;
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}
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/* Drops all capabiltiies held by the process
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*
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/* Drops all capabiltiies held by the process
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*
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* @returns: 0 on sucess, -1 on error
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*/
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static int drop_caps()
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@ -443,11 +473,11 @@ static int drop_caps()
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/*
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* Enables the per_syscall seccomp action for system calls
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*
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*
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* syscalls: array of system calls numbers. -1 must be the last entry.
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* per_syscall: action to apply for each system call
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* default_action: the default action at the end
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*
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*
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* @returns: 0 on success, -1 on error
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*/
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static int seccomp_enable(int *syscalls, unsigned int per_syscall, unsigned int default_action)
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@ -465,7 +495,7 @@ static int seccomp_enable(int *syscalls, unsigned int per_syscall, unsigned int
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struct sock_filter action = BPF_STMT(BPF_RET+BPF_K, per_syscall);
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filter[current_filter_index++] = syscall;
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filter[current_filter_index++] = action;
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++syscalls;
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}
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@ -478,7 +508,7 @@ static int seccomp_enable(int *syscalls, unsigned int per_syscall, unsigned int
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.filter = filter,
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};
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if (prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog) == -1)
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if (prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, &prog) == -1)
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{
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QSSB_LOG_ERROR("prctl SET_SECCOMP %s\n", strerror(errno));
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return -1;
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@ -489,7 +519,7 @@ static int seccomp_enable(int *syscalls, unsigned int per_syscall, unsigned int
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/*
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* Blacklists the specified systemcalls.
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*
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*
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* syscalls: array of system calls numbers. -1 must be the last entry.
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*/
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static int seccomp_enable_blacklist(int *syscalls)
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@ -499,7 +529,7 @@ static int seccomp_enable_blacklist(int *syscalls)
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/*
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* Blacklists the specified systemcalls.
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*
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*
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* syscalls: array of system calls numbers. -1 must be the last entry.
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*/
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static int seccomp_enable_whitelist(int *syscalls)
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@ -508,9 +538,117 @@ static int seccomp_enable_whitelist(int *syscalls)
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}
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#if HAVE_LANDLOCK == 1
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static int enable_landlock_policies(struct qssb_path_policy *policies)
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static unsigned int qssb_flags_to_landlock(unsigned int flags)
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{
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return 0;
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unsigned int result = 0;
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if(flags & QSSB_FS_ALLOW_DEV)
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{
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result |= LANDLOCK_ACCESS_FS_MAKE_BLOCK;
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result |= LANDLOCK_ACCESS_FS_MAKE_CHAR;
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}
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if(flags & QSSB_FS_ALLOW_MAKE_BLOCK)
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{
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result |= LANDLOCK_ACCESS_FS_MAKE_BLOCK;
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}
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if(flags & QSSB_FS_ALLOW_MAKE_CHAR)
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{
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result |= LANDLOCK_ACCESS_FS_MAKE_CHAR;
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}
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if(flags & QSSB_FS_ALLOW_MAKE_DIR)
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{
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result |= LANDLOCK_ACCESS_FS_MAKE_DIR;
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}
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if(flags & QSSB_FS_ALLOW_MAKE_FIFO)
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{
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result |= LANDLOCK_ACCESS_FS_MAKE_FIFO;
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}
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if(flags & QSSB_FS_ALLOW_MAKE_REG)
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{
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result |= LANDLOCK_ACCESS_FS_MAKE_REG;
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}
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if(flags & QSSB_FS_ALLOW_MAKE_SOCK)
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{
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result |= LANDLOCK_ACCESS_FS_MAKE_SOCK;
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}
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if(flags & QSSB_FS_ALLOW_MAKE_SYM)
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{
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result |= LANDLOCK_ACCESS_FS_MAKE_SYM;
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}
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if(flags & QSSB_FS_ALLOW_READ)
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{
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result |= LANDLOCK_ACCESS_FS_READ_FILE;
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result |= LANDLOCK_ACCESS_FS_READ_DIR;
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}
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if(flags & QSSB_FS_ALLOW_REMOVE)
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{
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result |= LANDLOCK_ACCESS_FS_REMOVE_DIR;
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result |= LANDLOCK_ACCESS_FS_REMOVE_FILE;
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}
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if(flags & QSSB_FS_ALLOW_REMOVE_DIR)
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{
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result |= LANDLOCK_ACCESS_FS_REMOVE_DIR;
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}
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if(flags & QSSB_FS_ALLOW_REMOVE_FILE)
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{
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result |= LANDLOCK_ACCESS_FS_REMOVE_FILE;
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}
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if(flags & QSSB_FS_ALLOW_EXEC)
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{
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result |= LANDLOCK_ACCESS_FS_EXECUTE;
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}
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if(flags & QSSB_FS_ALLOW_WRITE)
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{
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result |= LANDLOCK_ACCESS_FS_MAKE_REG;
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result |= LANDLOCK_ACCESS_FS_WRITE_FILE;
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}
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if(flags & QSSB_FS_ALLOW_WRITE_FILE)
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{
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result |= LANDLOCK_ACCESS_FS_WRITE_FILE;
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}
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if(flags & QSSB_FS_ALLOW_READ_DIR)
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{
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result |= LANDLOCK_ACCESS_FS_READ_DIR;
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}
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return result;
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}
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static int landlock_prepare_ruleset(struct qssb_path_policy *policies)
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{
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int ruleset_fd = -1;
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struct landlock_ruleset_attr ruleset_attr;
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/* We here want the maximum possible ruleset, so set the var to the max possible bitmask.
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Stolen/Adapted from: [linux src]/security/landlock/limits.h
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*/
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ruleset_attr.handled_access_fs = ((LANDLOCK_ACCESS_FS_MAKE_SYM << 1) - 1);
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ruleset_fd = landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0);
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if (ruleset_fd < 0)
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{
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QSSB_LOG_ERROR("Failed to create landlock ruleset");
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return -1;
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}
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struct qssb_path_policy *policy = policies;
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while(policy != NULL)
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{
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struct landlock_path_beneath_attr path_beneath;
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path_beneath.parent_fd = open(policy->path, O_PATH | O_CLOEXEC);
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if(path_beneath.parent_fd < 0)
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{
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QSSB_LOG_ERROR("Failed to open policy path %s while preparing landlock ruleset\n", policy->path);
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close(ruleset_fd);
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return path_beneath.parent_fd;
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}
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path_beneath.allowed_access = qssb_flags_to_landlock(policy->policy);
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int ret = landlock_add_rule(ruleset_fd, LANDLOCK_RULE_PATH_BENEATH, &path_beneath, 0);
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if(ret)
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{
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QSSB_LOG_ERROR("Failed to update ruleset while processsing policy path %s\n", policy->path);
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close(ruleset_fd);
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return ret;
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}
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policy = policy->next;
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}
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return ruleset_fd;
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}
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#endif
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@ -558,8 +696,8 @@ static int check_policy_sanity(struct qssb_policy *policy)
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}
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/* Enables the specified qssb_policy.
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*
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* The calling process is supposed *TO BE WRITTEN* if
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*
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* The calling process is supposed *TO BE WRITTEN* if
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* this function fails.
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* @returns: 0 on sucess, <0 on error
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*/
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@ -620,11 +758,13 @@ int qssb_enable_policy(struct qssb_policy *policy)
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}
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#if HAVE_LANDLOCK == 1
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int landlock_ruleset_fd = -1;
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if(policy->path_policies != NULL)
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{
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if(enable_landlock_policies(policy->path_policies) < 0)
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landlock_ruleset_fd = landlock_prepare_ruleset(policy->path_policies);
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if(landlock_ruleset_fd < 0)
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{
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QSSB_LOG_ERROR("enable_landlock_policies: Failed to enable landlock policies\n");
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QSSB_LOG_ERROR("landlock_prepare_ruleset: Failed to prepare landlock ruleset: %s\n", strerror(errno));
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return -1;
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}
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}
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@ -665,9 +805,19 @@ int qssb_enable_policy(struct qssb_policy *policy)
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{
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QSSB_LOG_ERROR("prctl: PR_SET_NO_NEW_PRIVS failed: %s\n", strerror(errno));
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return -1;
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}
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}
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}
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#if HAVE_LANDLOCK == 1
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if (policy->path_policies != NULL && landlock_restrict_self(landlock_ruleset_fd, 0) != 0)
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{
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perror("Failed to enforce ruleset");
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close(landlock_ruleset_fd);
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return -1;
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}
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close(landlock_ruleset_fd);
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#endif
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if(policy->allowed_syscalls != NULL)
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{
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if(seccomp_enable_whitelist(policy->allowed_syscalls) <0)
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