From cde1391a0b4014b0e8fc09cd316272f478b54c0f Mon Sep 17 00:00:00 2001 From: Roberto Sassu Date: Fri, 28 May 2021 09:38:06 +0200 Subject: [PATCH 1/7] ima: Add ima_show_template_uint() template library function This patch introduces the new function ima_show_template_uint(). This can be used for showing integers of different sizes in ASCII format. The function ima_show_template_data_ascii() automatically determines how to print a stored integer by checking the integer size. If integers have been written in canonical format, ima_show_template_data_ascii() calls the appropriate leXX_to_cpu() function to correctly display the value. Signed-off-by: Roberto Sassu Signed-off-by: Mimi Zohar --- security/integrity/ima/ima_template_lib.c | 38 ++++++++++++++++++++++- security/integrity/ima/ima_template_lib.h | 2 ++ 2 files changed, 39 insertions(+), 1 deletion(-) diff --git a/security/integrity/ima/ima_template_lib.c b/security/integrity/ima/ima_template_lib.c index 4314d9a3514c..f23296c33da1 100644 --- a/security/integrity/ima/ima_template_lib.c +++ b/security/integrity/ima/ima_template_lib.c @@ -24,7 +24,8 @@ enum data_formats { DATA_FMT_DIGEST = 0, DATA_FMT_DIGEST_WITH_ALGO, DATA_FMT_STRING, - DATA_FMT_HEX + DATA_FMT_HEX, + DATA_FMT_UINT }; static int ima_write_template_field_data(const void *data, const u32 datalen, @@ -88,6 +89,35 @@ static void ima_show_template_data_ascii(struct seq_file *m, case DATA_FMT_STRING: seq_printf(m, "%s", buf_ptr); break; + case DATA_FMT_UINT: + switch (field_data->len) { + case sizeof(u8): + seq_printf(m, "%u", *(u8 *)buf_ptr); + break; + case sizeof(u16): + if (ima_canonical_fmt) + seq_printf(m, "%u", + le16_to_cpu(*(u16 *)buf_ptr)); + else + seq_printf(m, "%u", *(u16 *)buf_ptr); + break; + case sizeof(u32): + if (ima_canonical_fmt) + seq_printf(m, "%u", + le32_to_cpu(*(u32 *)buf_ptr)); + else + seq_printf(m, "%u", *(u32 *)buf_ptr); + break; + case sizeof(u64): + if (ima_canonical_fmt) + seq_printf(m, "%llu", + le64_to_cpu(*(u64 *)buf_ptr)); + else + seq_printf(m, "%llu", *(u64 *)buf_ptr); + break; + default: + break; + } default: break; } @@ -163,6 +193,12 @@ void ima_show_template_buf(struct seq_file *m, enum ima_show_type show, ima_show_template_field_data(m, show, DATA_FMT_HEX, field_data); } +void ima_show_template_uint(struct seq_file *m, enum ima_show_type show, + struct ima_field_data *field_data) +{ + ima_show_template_field_data(m, show, DATA_FMT_UINT, field_data); +} + /** * ima_parse_buf() - Parses lengths and data from an input buffer * @bufstartp: Buffer start address. diff --git a/security/integrity/ima/ima_template_lib.h b/security/integrity/ima/ima_template_lib.h index f4b2a2056d1d..54b67c80b315 100644 --- a/security/integrity/ima/ima_template_lib.h +++ b/security/integrity/ima/ima_template_lib.h @@ -27,6 +27,8 @@ void ima_show_template_sig(struct seq_file *m, enum ima_show_type show, struct ima_field_data *field_data); void ima_show_template_buf(struct seq_file *m, enum ima_show_type show, struct ima_field_data *field_data); +void ima_show_template_uint(struct seq_file *m, enum ima_show_type show, + struct ima_field_data *field_data); int ima_parse_buf(void *bufstartp, void *bufendp, void **bufcurp, int maxfields, struct ima_field_data *fields, int *curfields, unsigned long *len_mask, int enforce_mask, char *bufname); From 7dcfeacc5a9d0c130160b86de23279793a8732c8 Mon Sep 17 00:00:00 2001 From: Roberto Sassu Date: Fri, 28 May 2021 09:38:07 +0200 Subject: [PATCH 2/7] ima: Define new template fields iuid and igid This patch defines the new template fields iuid and igid, which include respectively the inode UID and GID. For idmapped mounts, still the original UID and GID are provided. These fields can be used to verify the EVM portable signature, if it was included with the template fields sig or evmsig. Signed-off-by: Roberto Sassu Acked-by: Christian Brauner Signed-off-by: Mimi Zohar --- Documentation/security/IMA-templates.rst | 2 + security/integrity/ima/ima_template.c | 4 ++ security/integrity/ima/ima_template_lib.c | 45 +++++++++++++++++++++++ security/integrity/ima/ima_template_lib.h | 4 ++ 4 files changed, 55 insertions(+) diff --git a/Documentation/security/IMA-templates.rst b/Documentation/security/IMA-templates.rst index 9f3e86ab028a..bf8ce4cf5878 100644 --- a/Documentation/security/IMA-templates.rst +++ b/Documentation/security/IMA-templates.rst @@ -75,6 +75,8 @@ descriptors by adding their identifier to the format string - 'modsig' the appended file signature; - 'buf': the buffer data that was used to generate the hash without size limitations; - 'evmsig': the EVM portable signature; + - 'iuid': the inode UID; + - 'igid': the inode GID; Below, there is the list of defined template descriptors: diff --git a/security/integrity/ima/ima_template.c b/security/integrity/ima/ima_template.c index 7a60848c04a5..a5ecd9e2581b 100644 --- a/security/integrity/ima/ima_template.c +++ b/security/integrity/ima/ima_template.c @@ -47,6 +47,10 @@ static const struct ima_template_field supported_fields[] = { .field_show = ima_show_template_sig}, {.field_id = "evmsig", .field_init = ima_eventevmsig_init, .field_show = ima_show_template_sig}, + {.field_id = "iuid", .field_init = ima_eventinodeuid_init, + .field_show = ima_show_template_uint}, + {.field_id = "igid", .field_init = ima_eventinodegid_init, + .field_show = ima_show_template_uint}, }; /* diff --git a/security/integrity/ima/ima_template_lib.c b/security/integrity/ima/ima_template_lib.c index f23296c33da1..87b40f391739 100644 --- a/security/integrity/ima/ima_template_lib.c +++ b/security/integrity/ima/ima_template_lib.c @@ -551,3 +551,48 @@ int ima_eventevmsig_init(struct ima_event_data *event_data, kfree(xattr_data); return rc; } + +static int ima_eventinodedac_init_common(struct ima_event_data *event_data, + struct ima_field_data *field_data, + bool get_uid) +{ + unsigned int id; + + if (!event_data->file) + return 0; + + if (get_uid) + id = i_uid_read(file_inode(event_data->file)); + else + id = i_gid_read(file_inode(event_data->file)); + + if (ima_canonical_fmt) { + if (sizeof(id) == sizeof(u16)) + id = cpu_to_le16(id); + else + id = cpu_to_le32(id); + } + + return ima_write_template_field_data((void *)&id, sizeof(id), + DATA_FMT_UINT, field_data); +} + +/* + * ima_eventinodeuid_init - include the inode UID as part of the template + * data + */ +int ima_eventinodeuid_init(struct ima_event_data *event_data, + struct ima_field_data *field_data) +{ + return ima_eventinodedac_init_common(event_data, field_data, true); +} + +/* + * ima_eventinodegid_init - include the inode GID as part of the template + * data + */ +int ima_eventinodegid_init(struct ima_event_data *event_data, + struct ima_field_data *field_data) +{ + return ima_eventinodedac_init_common(event_data, field_data, false); +} diff --git a/security/integrity/ima/ima_template_lib.h b/security/integrity/ima/ima_template_lib.h index 54b67c80b315..b0aaf109f386 100644 --- a/security/integrity/ima/ima_template_lib.h +++ b/security/integrity/ima/ima_template_lib.h @@ -50,4 +50,8 @@ int ima_eventmodsig_init(struct ima_event_data *event_data, struct ima_field_data *field_data); int ima_eventevmsig_init(struct ima_event_data *event_data, struct ima_field_data *field_data); +int ima_eventinodeuid_init(struct ima_event_data *event_data, + struct ima_field_data *field_data); +int ima_eventinodegid_init(struct ima_event_data *event_data, + struct ima_field_data *field_data); #endif /* __LINUX_IMA_TEMPLATE_LIB_H */ From f8216f6b957f5657c5f4c97f4b037120c6f236bc Mon Sep 17 00:00:00 2001 From: Roberto Sassu Date: Fri, 28 May 2021 09:38:08 +0200 Subject: [PATCH 3/7] ima: Define new template field imode This patch defines the new template field imode, which includes the inode mode. It can be used by a remote verifier to verify the EVM portable signature, if it was included with the template fields sig or evmsig. Signed-off-by: Roberto Sassu Signed-off-by: Mimi Zohar --- Documentation/security/IMA-templates.rst | 1 + security/integrity/ima/ima_template.c | 2 ++ security/integrity/ima/ima_template_lib.c | 22 ++++++++++++++++++++++ security/integrity/ima/ima_template_lib.h | 2 ++ 4 files changed, 27 insertions(+) diff --git a/Documentation/security/IMA-templates.rst b/Documentation/security/IMA-templates.rst index bf8ce4cf5878..65c1ce451d08 100644 --- a/Documentation/security/IMA-templates.rst +++ b/Documentation/security/IMA-templates.rst @@ -77,6 +77,7 @@ descriptors by adding their identifier to the format string - 'evmsig': the EVM portable signature; - 'iuid': the inode UID; - 'igid': the inode GID; + - 'imode': the inode mode; Below, there is the list of defined template descriptors: diff --git a/security/integrity/ima/ima_template.c b/security/integrity/ima/ima_template.c index a5ecd9e2581b..43784f2bf8bd 100644 --- a/security/integrity/ima/ima_template.c +++ b/security/integrity/ima/ima_template.c @@ -51,6 +51,8 @@ static const struct ima_template_field supported_fields[] = { .field_show = ima_show_template_uint}, {.field_id = "igid", .field_init = ima_eventinodegid_init, .field_show = ima_show_template_uint}, + {.field_id = "imode", .field_init = ima_eventinodemode_init, + .field_show = ima_show_template_uint}, }; /* diff --git a/security/integrity/ima/ima_template_lib.c b/security/integrity/ima/ima_template_lib.c index 87b40f391739..3156fb34b1af 100644 --- a/security/integrity/ima/ima_template_lib.c +++ b/security/integrity/ima/ima_template_lib.c @@ -596,3 +596,25 @@ int ima_eventinodegid_init(struct ima_event_data *event_data, { return ima_eventinodedac_init_common(event_data, field_data, false); } + +/* + * ima_eventinodemode_init - include the inode mode as part of the template + * data + */ +int ima_eventinodemode_init(struct ima_event_data *event_data, + struct ima_field_data *field_data) +{ + struct inode *inode; + umode_t mode; + + if (!event_data->file) + return 0; + + inode = file_inode(event_data->file); + mode = inode->i_mode; + if (ima_canonical_fmt) + mode = cpu_to_le16(mode); + + return ima_write_template_field_data((char *)&mode, sizeof(mode), + DATA_FMT_UINT, field_data); +} diff --git a/security/integrity/ima/ima_template_lib.h b/security/integrity/ima/ima_template_lib.h index b0aaf109f386..6509af4a97ee 100644 --- a/security/integrity/ima/ima_template_lib.h +++ b/security/integrity/ima/ima_template_lib.h @@ -54,4 +54,6 @@ int ima_eventinodeuid_init(struct ima_event_data *event_data, struct ima_field_data *field_data); int ima_eventinodegid_init(struct ima_event_data *event_data, struct ima_field_data *field_data); +int ima_eventinodemode_init(struct ima_event_data *event_data, + struct ima_field_data *field_data); #endif /* __LINUX_IMA_TEMPLATE_LIB_H */ From 8c7a703ec9787a1b45b024e9acd253328422dcbd Mon Sep 17 00:00:00 2001 From: Roberto Sassu Date: Fri, 28 May 2021 09:38:09 +0200 Subject: [PATCH 4/7] evm: Verify portable signatures against all protected xattrs Currently, the evm_config_default_xattrnames array contains xattr names only related to LSMs which are enabled in the kernel configuration. However, EVM portable signatures do not depend on local information and a vendor might include in the signature calculation xattrs that are not enabled in the target platform. Just including all xattrs names in evm_config_default_xattrnames is not a safe approach, because a target system might have already calculated signatures or HMACs based only on the enabled xattrs. After applying this patch, EVM would verify those signatures and HMACs with all xattrs instead. The non-enabled ones, which could possibly exist, would cause a verification error. Thus, this patch adds a new field named enabled to the xattr_list structure, which is set to true if the LSM associated to a given xattr name is enabled in the kernel configuration. The non-enabled xattrs are taken into account only in evm_calc_hmac_or_hash(), if the passed security.evm type is EVM_XATTR_PORTABLE_DIGSIG. The new function evm_protected_xattr_if_enabled() has been defined so that IMA can include all protected xattrs and not only the enabled ones in the measurement list, if the new template fields xattrnames, xattrlengths or xattrvalues have been included in the template format. Signed-off-by: Roberto Sassu Signed-off-by: Mimi Zohar --- include/linux/evm.h | 6 ++++ security/integrity/evm/evm.h | 1 + security/integrity/evm/evm_crypto.c | 7 ++++ security/integrity/evm/evm_main.c | 56 +++++++++++++++++++++++------ security/integrity/evm/evm_secfs.c | 16 +++++++-- 5 files changed, 74 insertions(+), 12 deletions(-) diff --git a/include/linux/evm.h b/include/linux/evm.h index 31ef1dbbb3ac..5011a299c251 100644 --- a/include/linux/evm.h +++ b/include/linux/evm.h @@ -38,6 +38,7 @@ extern int evm_inode_init_security(struct inode *inode, const struct xattr *xattr_array, struct xattr *evm); extern bool evm_revalidate_status(const char *xattr_name); +extern int evm_protected_xattr_if_enabled(const char *req_xattr_name); #ifdef CONFIG_FS_POSIX_ACL extern int posix_xattr_acl(const char *xattrname); #else @@ -114,5 +115,10 @@ static inline bool evm_revalidate_status(const char *xattr_name) return false; } +static inline int evm_protected_xattr_if_enabled(const char *req_xattr_name) +{ + return false; +} + #endif /* CONFIG_EVM */ #endif /* LINUX_EVM_H */ diff --git a/security/integrity/evm/evm.h b/security/integrity/evm/evm.h index f2fef2b5ed51..0d44f41d16f8 100644 --- a/security/integrity/evm/evm.h +++ b/security/integrity/evm/evm.h @@ -29,6 +29,7 @@ struct xattr_list { struct list_head list; char *name; + bool enabled; }; extern int evm_initialized; diff --git a/security/integrity/evm/evm_crypto.c b/security/integrity/evm/evm_crypto.c index d76b006cbcc4..1628e2ca9862 100644 --- a/security/integrity/evm/evm_crypto.c +++ b/security/integrity/evm/evm_crypto.c @@ -216,6 +216,13 @@ static int evm_calc_hmac_or_hash(struct dentry *dentry, if (strcmp(xattr->name, XATTR_NAME_IMA) == 0) is_ima = true; + /* + * Skip non-enabled xattrs for locally calculated + * signatures/HMACs. + */ + if (type != EVM_XATTR_PORTABLE_DIGSIG && !xattr->enabled) + continue; + if ((req_xattr_name && req_xattr_value) && !strcmp(xattr->name, req_xattr_name)) { error = 0; diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c index 0196168aeb7d..ee4e17a790fb 100644 --- a/security/integrity/evm/evm_main.c +++ b/security/integrity/evm/evm_main.c @@ -34,24 +34,44 @@ static const char * const integrity_status_msg[] = { int evm_hmac_attrs; static struct xattr_list evm_config_default_xattrnames[] = { + {.name = XATTR_NAME_SELINUX, #ifdef CONFIG_SECURITY_SELINUX - {.name = XATTR_NAME_SELINUX}, + .enabled = true #endif + }, + {.name = XATTR_NAME_SMACK, #ifdef CONFIG_SECURITY_SMACK - {.name = XATTR_NAME_SMACK}, + .enabled = true +#endif + }, + {.name = XATTR_NAME_SMACKEXEC, #ifdef CONFIG_EVM_EXTRA_SMACK_XATTRS - {.name = XATTR_NAME_SMACKEXEC}, - {.name = XATTR_NAME_SMACKTRANSMUTE}, - {.name = XATTR_NAME_SMACKMMAP}, + .enabled = true #endif + }, + {.name = XATTR_NAME_SMACKTRANSMUTE, +#ifdef CONFIG_EVM_EXTRA_SMACK_XATTRS + .enabled = true #endif + }, + {.name = XATTR_NAME_SMACKMMAP, +#ifdef CONFIG_EVM_EXTRA_SMACK_XATTRS + .enabled = true +#endif + }, + {.name = XATTR_NAME_APPARMOR, #ifdef CONFIG_SECURITY_APPARMOR - {.name = XATTR_NAME_APPARMOR}, + .enabled = true #endif + }, + {.name = XATTR_NAME_IMA, #ifdef CONFIG_IMA_APPRAISE - {.name = XATTR_NAME_IMA}, + .enabled = true #endif - {.name = XATTR_NAME_CAPS}, + }, + {.name = XATTR_NAME_CAPS, + .enabled = true + }, }; LIST_HEAD(evm_config_xattrnames); @@ -76,7 +96,9 @@ static void __init evm_init_config(void) pr_info("Initialising EVM extended attributes:\n"); for (i = 0; i < xattrs; i++) { - pr_info("%s\n", evm_config_default_xattrnames[i].name); + pr_info("%s%s\n", evm_config_default_xattrnames[i].name, + !evm_config_default_xattrnames[i].enabled ? + " (disabled)" : ""); list_add_tail(&evm_config_default_xattrnames[i].list, &evm_config_xattrnames); } @@ -257,7 +279,8 @@ out: return evm_status; } -static int evm_protected_xattr(const char *req_xattr_name) +static int evm_protected_xattr_common(const char *req_xattr_name, + bool all_xattrs) { int namelen; int found = 0; @@ -265,6 +288,9 @@ static int evm_protected_xattr(const char *req_xattr_name) namelen = strlen(req_xattr_name); list_for_each_entry_lockless(xattr, &evm_config_xattrnames, list) { + if (!all_xattrs && !xattr->enabled) + continue; + if ((strlen(xattr->name) == namelen) && (strncmp(req_xattr_name, xattr->name, namelen) == 0)) { found = 1; @@ -281,6 +307,16 @@ static int evm_protected_xattr(const char *req_xattr_name) return found; } +static int evm_protected_xattr(const char *req_xattr_name) +{ + return evm_protected_xattr_common(req_xattr_name, false); +} + +int evm_protected_xattr_if_enabled(const char *req_xattr_name) +{ + return evm_protected_xattr_common(req_xattr_name, true); +} + /** * evm_verifyxattr - verify the integrity of the requested xattr * @dentry: object of the verify xattr diff --git a/security/integrity/evm/evm_secfs.c b/security/integrity/evm/evm_secfs.c index 5f0da41bccd0..a99676eb7f41 100644 --- a/security/integrity/evm/evm_secfs.c +++ b/security/integrity/evm/evm_secfs.c @@ -139,8 +139,12 @@ static ssize_t evm_read_xattrs(struct file *filp, char __user *buf, if (rc) return -ERESTARTSYS; - list_for_each_entry(xattr, &evm_config_xattrnames, list) + list_for_each_entry(xattr, &evm_config_xattrnames, list) { + if (!xattr->enabled) + continue; + size += strlen(xattr->name) + 1; + } temp = kmalloc(size + 1, GFP_KERNEL); if (!temp) { @@ -149,6 +153,9 @@ static ssize_t evm_read_xattrs(struct file *filp, char __user *buf, } list_for_each_entry(xattr, &evm_config_xattrnames, list) { + if (!xattr->enabled) + continue; + sprintf(temp + offset, "%s\n", xattr->name); offset += strlen(xattr->name) + 1; } @@ -199,6 +206,7 @@ static ssize_t evm_write_xattrs(struct file *file, const char __user *buf, goto out; } + xattr->enabled = true; xattr->name = memdup_user_nul(buf, count); if (IS_ERR(xattr->name)) { err = PTR_ERR(xattr->name); @@ -245,6 +253,10 @@ static ssize_t evm_write_xattrs(struct file *file, const char __user *buf, list_for_each_entry(tmp, &evm_config_xattrnames, list) { if (strcmp(xattr->name, tmp->name) == 0) { err = -EEXIST; + if (!tmp->enabled) { + tmp->enabled = true; + err = count; + } mutex_unlock(&xattr_list_mutex); goto out; } @@ -256,7 +268,7 @@ static ssize_t evm_write_xattrs(struct file *file, const char __user *buf, audit_log_end(ab); return count; out: - audit_log_format(ab, " res=%d", err); + audit_log_format(ab, " res=%d", (err < 0) ? err : 0); audit_log_end(ab); if (xattr) { kfree(xattr->name); From 8314b6732ae4e600bb933e108f96ce0176acb09c Mon Sep 17 00:00:00 2001 From: Roberto Sassu Date: Tue, 1 Jun 2021 10:23:38 +0200 Subject: [PATCH 5/7] ima: Define new template fields xattrnames, xattrlengths and xattrvalues This patch defines the new template fields xattrnames, xattrlengths and xattrvalues, which contain respectively a list of xattr names (strings, separated by |), lengths (u32, hex) and values (hex). If an xattr is not present, the name and length are not displayed in the measurement list. Reported-by: kernel test robot (Missing prototype def) Signed-off-by: Roberto Sassu Signed-off-by: Mimi Zohar --- Documentation/security/IMA-templates.rst | 4 ++ include/linux/evm.h | 10 ++++ security/integrity/evm/evm_main.c | 69 +++++++++++++++++++++++ security/integrity/ima/ima_template.c | 9 +++ security/integrity/ima/ima_template_lib.c | 64 +++++++++++++++++++++ security/integrity/ima/ima_template_lib.h | 6 ++ 6 files changed, 162 insertions(+) diff --git a/Documentation/security/IMA-templates.rst b/Documentation/security/IMA-templates.rst index 65c1ce451d08..6a58760a0a35 100644 --- a/Documentation/security/IMA-templates.rst +++ b/Documentation/security/IMA-templates.rst @@ -78,6 +78,10 @@ descriptors by adding their identifier to the format string - 'iuid': the inode UID; - 'igid': the inode GID; - 'imode': the inode mode; + - 'xattrnames': a list of xattr names (separated by |), only if the xattr is + present; + - 'xattrlengths': a list of xattr lengths (u32), only if the xattr is present; + - 'xattrvalues': a list of xattr values; Below, there is the list of defined template descriptors: diff --git a/include/linux/evm.h b/include/linux/evm.h index 5011a299c251..4c374be70247 100644 --- a/include/linux/evm.h +++ b/include/linux/evm.h @@ -39,6 +39,9 @@ extern int evm_inode_init_security(struct inode *inode, struct xattr *evm); extern bool evm_revalidate_status(const char *xattr_name); extern int evm_protected_xattr_if_enabled(const char *req_xattr_name); +extern int evm_read_protected_xattrs(struct dentry *dentry, u8 *buffer, + int buffer_size, char type, + bool canonical_fmt); #ifdef CONFIG_FS_POSIX_ACL extern int posix_xattr_acl(const char *xattrname); #else @@ -120,5 +123,12 @@ static inline int evm_protected_xattr_if_enabled(const char *req_xattr_name) return false; } +static inline int evm_read_protected_xattrs(struct dentry *dentry, u8 *buffer, + int buffer_size, char type, + bool canonical_fmt) +{ + return -EOPNOTSUPP; +} + #endif /* CONFIG_EVM */ #endif /* LINUX_EVM_H */ diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c index ee4e17a790fb..2c226e634ae9 100644 --- a/security/integrity/evm/evm_main.c +++ b/security/integrity/evm/evm_main.c @@ -317,6 +317,75 @@ int evm_protected_xattr_if_enabled(const char *req_xattr_name) return evm_protected_xattr_common(req_xattr_name, true); } +/** + * evm_read_protected_xattrs - read EVM protected xattr names, lengths, values + * @dentry: dentry of the read xattrs + * @inode: inode of the read xattrs + * @buffer: buffer xattr names, lengths or values are copied to + * @buffer_size: size of buffer + * @type: n: names, l: lengths, v: values + * @canonical_fmt: data format (true: little endian, false: native format) + * + * Read protected xattr names (separated by |), lengths (u32) or values for a + * given dentry and return the total size of copied data. If buffer is NULL, + * just return the total size. + * + * Returns the total size on success, a negative value on error. + */ +int evm_read_protected_xattrs(struct dentry *dentry, u8 *buffer, + int buffer_size, char type, bool canonical_fmt) +{ + struct xattr_list *xattr; + int rc, size, total_size = 0; + + list_for_each_entry_lockless(xattr, &evm_config_xattrnames, list) { + rc = __vfs_getxattr(dentry, d_backing_inode(dentry), + xattr->name, NULL, 0); + if (rc < 0 && rc == -ENODATA) + continue; + else if (rc < 0) + return rc; + + switch (type) { + case 'n': + size = strlen(xattr->name) + 1; + if (buffer) { + if (total_size) + *(buffer + total_size - 1) = '|'; + + memcpy(buffer + total_size, xattr->name, size); + } + break; + case 'l': + size = sizeof(u32); + if (buffer) { + if (canonical_fmt) + rc = cpu_to_le32(rc); + + *(u32 *)(buffer + total_size) = rc; + } + break; + case 'v': + size = rc; + if (buffer) { + rc = __vfs_getxattr(dentry, + d_backing_inode(dentry), xattr->name, + buffer + total_size, + buffer_size - total_size); + if (rc < 0) + return rc; + } + break; + default: + return -EINVAL; + } + + total_size += size; + } + + return total_size; +} + /** * evm_verifyxattr - verify the integrity of the requested xattr * @dentry: object of the verify xattr diff --git a/security/integrity/ima/ima_template.c b/security/integrity/ima/ima_template.c index 43784f2bf8bd..159a31d2fcdf 100644 --- a/security/integrity/ima/ima_template.c +++ b/security/integrity/ima/ima_template.c @@ -53,6 +53,15 @@ static const struct ima_template_field supported_fields[] = { .field_show = ima_show_template_uint}, {.field_id = "imode", .field_init = ima_eventinodemode_init, .field_show = ima_show_template_uint}, + {.field_id = "xattrnames", + .field_init = ima_eventinodexattrnames_init, + .field_show = ima_show_template_string}, + {.field_id = "xattrlengths", + .field_init = ima_eventinodexattrlengths_init, + .field_show = ima_show_template_sig}, + {.field_id = "xattrvalues", + .field_init = ima_eventinodexattrvalues_init, + .field_show = ima_show_template_sig}, }; /* diff --git a/security/integrity/ima/ima_template_lib.c b/security/integrity/ima/ima_template_lib.c index 3156fb34b1af..518fd50ea48a 100644 --- a/security/integrity/ima/ima_template_lib.c +++ b/security/integrity/ima/ima_template_lib.c @@ -11,6 +11,7 @@ #include "ima_template_lib.h" #include +#include static bool ima_template_hash_algo_allowed(u8 algo) { @@ -618,3 +619,66 @@ int ima_eventinodemode_init(struct ima_event_data *event_data, return ima_write_template_field_data((char *)&mode, sizeof(mode), DATA_FMT_UINT, field_data); } + +static int ima_eventinodexattrs_init_common(struct ima_event_data *event_data, + struct ima_field_data *field_data, + char type) +{ + u8 *buffer = NULL; + int rc; + + if (!event_data->file) + return 0; + + rc = evm_read_protected_xattrs(file_dentry(event_data->file), NULL, 0, + type, ima_canonical_fmt); + if (rc < 0) + return 0; + + buffer = kmalloc(rc, GFP_KERNEL); + if (!buffer) + return 0; + + rc = evm_read_protected_xattrs(file_dentry(event_data->file), buffer, + rc, type, ima_canonical_fmt); + if (rc < 0) { + rc = 0; + goto out; + } + + rc = ima_write_template_field_data((char *)buffer, rc, DATA_FMT_HEX, + field_data); +out: + kfree(buffer); + return rc; +} + +/* + * ima_eventinodexattrnames_init - include a list of xattr names as part of the + * template data + */ +int ima_eventinodexattrnames_init(struct ima_event_data *event_data, + struct ima_field_data *field_data) +{ + return ima_eventinodexattrs_init_common(event_data, field_data, 'n'); +} + +/* + * ima_eventinodexattrlengths_init - include a list of xattr lengths as part of + * the template data + */ +int ima_eventinodexattrlengths_init(struct ima_event_data *event_data, + struct ima_field_data *field_data) +{ + return ima_eventinodexattrs_init_common(event_data, field_data, 'l'); +} + +/* + * ima_eventinodexattrvalues_init - include a list of xattr values as part of + * the template data + */ +int ima_eventinodexattrvalues_init(struct ima_event_data *event_data, + struct ima_field_data *field_data) +{ + return ima_eventinodexattrs_init_common(event_data, field_data, 'v'); +} diff --git a/security/integrity/ima/ima_template_lib.h b/security/integrity/ima/ima_template_lib.h index 6509af4a97ee..c71f1de95753 100644 --- a/security/integrity/ima/ima_template_lib.h +++ b/security/integrity/ima/ima_template_lib.h @@ -56,4 +56,10 @@ int ima_eventinodegid_init(struct ima_event_data *event_data, struct ima_field_data *field_data); int ima_eventinodemode_init(struct ima_event_data *event_data, struct ima_field_data *field_data); +int ima_eventinodexattrnames_init(struct ima_event_data *event_data, + struct ima_field_data *field_data); +int ima_eventinodexattrlengths_init(struct ima_event_data *event_data, + struct ima_field_data *field_data); +int ima_eventinodexattrvalues_init(struct ima_event_data *event_data, + struct ima_field_data *field_data); #endif /* __LINUX_IMA_TEMPLATE_LIB_H */ From 88016de3ab075790e1f1bf047576e9b557c22d19 Mon Sep 17 00:00:00 2001 From: Roberto Sassu Date: Thu, 3 Jun 2021 15:17:05 +0200 Subject: [PATCH 6/7] ima: Define new template evm-sig With the recent introduction of the evmsig template field, remote verifiers can obtain the EVM portable signature instead of the IMA signature, to verify file metadata. After introducing the new fields to include file metadata in the measurement list, this patch finally defines the evm-sig template, whose format is: d-ng|n-ng|evmsig|xattrnames|xattrlengths|xattrvalues|iuid|igid|imode xattrnames, xattrlengths and xattrvalues are populated only from defined EVM protected xattrs, i.e. the ones that EVM considers to verify the portable signature. xattrnames and xattrlengths are populated only if the xattr is present. xattrnames and xattrlengths are not necessary for verifying the EVM portable signature, but they are included for completeness of information, if a remote verifier wants to infer more from file metadata. Signed-off-by: Roberto Sassu Signed-off-by: Mimi Zohar --- Documentation/security/IMA-templates.rst | 1 + security/integrity/ima/ima_template.c | 5 ++++- 2 files changed, 5 insertions(+), 1 deletion(-) diff --git a/Documentation/security/IMA-templates.rst b/Documentation/security/IMA-templates.rst index 6a58760a0a35..5adc22f99496 100644 --- a/Documentation/security/IMA-templates.rst +++ b/Documentation/security/IMA-templates.rst @@ -91,6 +91,7 @@ Below, there is the list of defined template descriptors: - "ima-sig": its format is ``d-ng|n-ng|sig``; - "ima-buf": its format is ``d-ng|n-ng|buf``; - "ima-modsig": its format is ``d-ng|n-ng|sig|d-modsig|modsig``; + - "evm-sig": its format is ``d-ng|n-ng|evmsig|xattrnames|xattrlengths|xattrvalues|iuid|igid|imode``; Use diff --git a/security/integrity/ima/ima_template.c b/security/integrity/ima/ima_template.c index 159a31d2fcdf..a85963853a91 100644 --- a/security/integrity/ima/ima_template.c +++ b/security/integrity/ima/ima_template.c @@ -22,6 +22,8 @@ static struct ima_template_desc builtin_templates[] = { {.name = "ima-sig", .fmt = "d-ng|n-ng|sig"}, {.name = "ima-buf", .fmt = "d-ng|n-ng|buf"}, {.name = "ima-modsig", .fmt = "d-ng|n-ng|sig|d-modsig|modsig"}, + {.name = "evm-sig", + .fmt = "d-ng|n-ng|evmsig|xattrnames|xattrlengths|xattrvalues|iuid|igid|imode"}, {.name = "", .fmt = ""}, /* placeholder for a custom format */ }; @@ -69,7 +71,8 @@ static const struct ima_template_field supported_fields[] = { * need to be accounted for since they shouldn't be defined in the same template * description as 'd-ng' and 'n-ng' respectively. */ -#define MAX_TEMPLATE_NAME_LEN sizeof("d-ng|n-ng|sig|buf|d-modisg|modsig") +#define MAX_TEMPLATE_NAME_LEN \ + sizeof("d-ng|n-ng|evmsig|xattrnames|xattrlengths|xattrvalues|iuid|igid|imode") static struct ima_template_desc *ima_template; static struct ima_template_desc *ima_buf_template; From d721c15fd519c08819fbc6de39b713e2ed1d9894 Mon Sep 17 00:00:00 2001 From: Roberto Sassu Date: Fri, 28 May 2021 09:38:12 +0200 Subject: [PATCH 7/7] evm: Don't return an error in evm_write_xattrs() if audit is not enabled This patch avoids that evm_write_xattrs() returns an error when audit is not enabled. The ab variable can be NULL and still be passed to the other audit_log_() functions, as those functions do not include any instruction. Signed-off-by: Roberto Sassu Signed-off-by: Mimi Zohar --- security/integrity/evm/evm_secfs.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/security/integrity/evm/evm_secfs.c b/security/integrity/evm/evm_secfs.c index a99676eb7f41..8a9db7dfca7e 100644 --- a/security/integrity/evm/evm_secfs.c +++ b/security/integrity/evm/evm_secfs.c @@ -197,7 +197,7 @@ static ssize_t evm_write_xattrs(struct file *file, const char __user *buf, ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_INTEGRITY_EVM_XATTR); - if (!ab) + if (!ab && IS_ENABLED(CONFIG_AUDIT)) return -ENOMEM; xattr = kmalloc(sizeof(struct xattr_list), GFP_KERNEL);